G'MIC(1)

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NAME
gmic - Perform image processing operations using the G'MIC framework.

HELP
  gmic: GREYC's Magic for Image Computing.
        (https://gmic.eu)

        Version 2.7.2
        Copyright (c) 2008-2019, David Tschumperle / GREYC Lab / CNRS.
        (https://www.greyc.fr)
 1. Usage
    gmic [command1 [arg1_1,arg1_2,..]] .. [commandN [argN_1,argN_2,..]]

    'gmic' is the open-source interpreter of the G'MIC language, a script-based programming
    language dedicated to the design of possibly complex image processing pipelines and operators.
    It can be used to convert, manipulate, filter and visualize image datasets made of one
    or several 1D/2D or 3D multi-spectral images.

    This reference documentation describes all the technical rules governing the G'MIC language.
    As a starting point, you may want to visit our detailed tutorial pages, at:
     https://gmic.eu/tutorial/
 2. Overall context
  - At any time, G'MIC manages one list of numbered (and optionally named) pixel-based images,
     entirely stored in computer memory (uncompressed).

  - The first image of the list has index '0' and is denoted by '[0]'. The second image of the
     list is denoted by '[1]', the third by '[2]' and so on.

  - Negative indices are treated in a periodic way: '[-1]' refers to the last image of the list,
     '[-2]' to the penultimate one, etc. Thus, if the list has 4 images, '[1]' and '[-3]' both
     designate the second image of the list.

  - A named image may be also indicated by '[name]', if 'name' uses the character set [a-zA-Z0-9_]
     and does not start with a number. Image names can be set or reassigned at any moment during
     the processing pipeline (see command 'name' for this purpose).

  - G'MIC defines a set of various commands and substitution mechanisms to allow the design of
     complex pipelines and operators managing this list of images, in a very flexible way:
     You can insert or remove images in the list, rearrange image order, process images
     (individually or grouped), merge image data together, display and output image files, etc.

  - Such a pipeline can be then added as a new custom G'MIC command (stored in a user
     command file), so it can be re-used afterwards in a larger pipeline if necessary.
 3. Image definition and terminology
  - In G'MIC, each image is modeled as a 1D, 2D, 3D or 4D array of scalar values, uniformly
     discretized on a rectangular/parallelepipedic domain.

  - The four dimensions of this array are respectively denoted by:

    . 'width', the number of image columns (size along the 'x'-axis).
    . 'height', the number of image rows (size along the 'y'-axis).
    . 'depth', the number of image slices (size along the 'z'-axis).
        (the depth is equal to 1 for usual color or grayscale 2D images).
    . 'spectrum', the number of image channels (size along the 'c'-axis).
        (the spectrum is respectively equal to 3 and 4 for usual RGB and RGBA color images).

  - There are no hard limitations on the size of the image along each dimension. For instance,
     the number of image slices or channels can be of arbitrary size within the limits of
     the available memory.

  - The width, height and depth of an image are considered as spatial dimensions, while the
     spectrum has a multi-spectral meaning. Thus, a 4D image in G'MIC should be most often
     regarded as a 3D dataset of multi-spectral voxels. Most of the G'MIC commands will stick with
     this idea (e.g. command 'blur' blurs images only along the spatial 'xyz'-axes).

  - G'MIC stores all the image data as buffers of 'float' values (32 bits, value range
     [-3.4E38,+3.4E38]). It performs all its image processing operations with floating point
     numbers. Each image pixel takes then 32bits/channel (except if double-precision buffers have
     been enabled during the compilation of the software, in which case 64bits/channel can be the
     default).

  - Considering 'float'-valued pixels ensure to keep the numerical precision when executing
     image processing pipelines. For image input/output operations, you may want to prescribe the
     image datatype to be different than 'float' (like 'bool', 'char', 'int', etc...).
     This is possible by specifying it as a file option when using I/O commands.
     (see section 'Input/output properties' to learn more about file options).
 4. Items of a processing pipeline
  - In G'MIC, an image processing pipeline is described as a sequence of items separated by the
     space character ' '. Such items are interpreted and executed from the left to the right.
     For instance, the expression:

       filename.jpg blur 3,0 sharpen 10 resize 200%,200% output file_out.jpg

     defines a valid pipeline composed of nine G'MIC items.

  - Each G'MIC item is a string that is either a command, a list of command arguments,
     a filename, or a special input string.

  - Escape characters '\' and double quotes '"' can be used to define items containing spaces or
     other special characters. For instance, the two strings 'single\ item' and '"single item"'
     both define the same single item, with a space in it.
 5. Input data items
  - If a specified G'MIC item appears to be an existing filename, the corresponding image data
     are loaded and inserted at the end of the image list (which is equivalent to the use of
     'input filename').

  - Special filenames '-' and '-.ext' stand for the standard input/output streams, optionally
     forced to be in a specific 'ext' file format (e.g. '-.jpg' or '-.png').

  - The following special input strings may be used as G'MIC items to create and insert new
     images with prescribed values, at the end of the image list:

    . '[selection]' or '[selection]xN': Insert 1 or N copies of already existing images.
       'selection' may represent one or several images
       (see section 'Command items and selections' to learn more about selections).

    . 'width[%],_height[%],_depth[%],_spectrum[%],_values': Insert a new image with specified
       size and values (adding '%' to a dimension means 'percentage of the size along the same
       axis, taken from the last image '[-1]''). Any specified dimension can be also written as
       '[image]', and is then set to the size (along the same axis) of the existing specified image
       [image]. 'values' can be either a sequence of numbers separated by commas ',',
       or a mathematical expression, as e.g. in input item '256,256,1,3,[x,y,128]' which
       creates a 256x256 RGB color image with a spatial shading on the red and green channels.
       (see section 'Mathematical expressions' to learn more about mathematical expressions).

    . '(v1,v2,..)': Insert a new image from specified prescribed values. Value separator inside
       parentheses can be ',' (column separator), ';' (row separator), '/' (slice separator) or
       '^' (channel separator). For instance, expression '(1,2,3;4,5,6;7,8,9)' creates a
        3x3 matrix (scalar image), with values running from 1 to 9.

    . '0': Insert a new 'empty' image, containing no pixel data.
       Empty images are used only in rare occasions.

  - Input item 'name=value' declares a new variable 'name', or assign a new string value
     to an existing variable. Variable names must use the character set [a-zA-Z0-9_] and cannot
     start with a number.

  - A variable definition is always local to the current command except when it starts by the
     underscore character '_'. In that case, it becomes also accessible by any command invoked
     outside the current command scope (global variable).

  - If a variable name starts with two underscores '__', the global variable is also shared among
     different threads and can be read/set by commands running in parallel (see command 'parallel'
     for this purpose). Otherwise, it remains local to the thread that defined it.

  - Numerical variables can be updated with the use of these special operators:
     '+=' (addition), '-=' (subtraction), '*=' (multiplication), '/=' (division), '%=' (modulo),
     '&=' (bitwise and), '|=' (bitwise or), '^=' (power), '<<=' and '>>=' (bitwise left and right
     shifts). For instance, 'foo=1 foo+=3'.

  - Input item 'name.=string' concatenates specified 'string' to the end of variable 'name'.

  - Multiple variable assignments and updates are allowed, with expressions:
     'name1,name2,...,nameN=value' or 'name1,name2,...,nameN=value1,value2,...,valueN'
     where assignment operator '=' can be replaced by one of the allowed operators
     (e.g. '+=').

  - Variables usually store numbers or strings. Use command 'store' to assign variables from image data.
      (and command 'restore' to access it afterwards).
 6. Command items and selections
  - A G'MIC item that is not a filename nor a special input string designates a command,
     most of the time. Generally, commands perform image processing operations on one or several
     available images of the list.

  - Reccurent commands have two equivalent names (regular and short). For instance, command names
     'resize' and 'r' refer to the same image resizing action.

  - A G'MIC command may have mandatory or optional arguments. Command arguments must be specified
     in the next item on the command line. Commas ',' are used to separate multiple arguments of a
     single command, when required.

  - The execution of a G'MIC command may be restricted only to a subset of the image list, by
     appending '[selection]' to the command name. Examples of valid syntaxes for 'selection' are:

    . 'command[-2]': Apply command only on the penultimate image [-2] of the list.
    . 'command[0,1,3]': Apply command only on images [0],[1] and [3].
    . 'command[3-6]': Apply command only on images [3] to [6] (i.e, [3],[4],[5] and [6]).
    . 'command[50%-100%]': Apply command only on the second half of the image list.
    . 'command[0,-4--1]': Apply command only on the first image and the last four images.
    . 'command[0-9:3]': Apply command only on images [0] to [9], with a step of 3
                        (i.e. on images [0], [3], [6] and [9]).
    . 'command[0-9:25%]': Apply command only on images [0] to [9], with a step of 25%
                        (i.e. on images [0], [3], [6] and [9]).
    . 'command[0--1:2]': Apply command only on images of the list with even indices.
    . 'command[0,2-4,50%--1]': Apply command on images [0],[2],[3],[4] and on the second half of
                        the image list.
    . 'command[^0,1]': Apply command on all images except the first two.
    . 'command[name1,name2]': Apply command on named images 'name1' and 'name2'.

  - indices in selections are always sorted in increasing order, and duplicate indices are
     discarded. For instance, selections '[3-1,1-3]' and '[1,1,1,3,2]' are both equivalent to
     '[1-3]'. If you want to repeat a single command multiple times on an image, use a
     'repeat..done' loop instead. Inverting the order of images for a command is achieved by
     explicitly inverting the order of the images in the list, with command 'reverse[selection]'.

  - Command selections '[-1]','[-2]' and '[-3]' are so often used they have their own
     shortcuts, respectively '.', '..' and '...'. For instance, command 'blur..' is equivalent to
     'blur[-2]'. These shortcuts work also when specifying command arguments.

  - G'MIC commands invoked without '[selection]' are applied on all images of the list, i.e. the
     default selection is '[0--1]' (except for command 'input' whose default selection is '[-1]').

  - Prepending a single hyphen '-' to a G'MIC command is allowed. This may be useful to recognize
     command items more easily in a one-liner pipeline (typically invoked from a shell).

  - A G'MIC command prepended with a plus sign '+' or a double hyphen '--' does not act 'in-place'
     but inserts its result as one or several new images at the end of the image list.

  - There are two different types of commands that can be run by the G'MIC interpreter:

    . Builtin commands, are the hard-coded functionalities in the interpreter core. They are thus
       compiled as binary code and run fast, most of the time. Omitting an argument when invoking a
       builtin command is not permitted, except if all following arguments are also omitted.
       For instance, invoking 'plasma 10,,5' is invalid but 'plasma 10' is correct.
    . Custom commands, are defined as G'MIC pipelines of builtin or other custom commands.
       They are interpreted by the G'MIC interpreter, and thus run a bit slower than builtin commands.
       Omitting arguments when invoking a custom command is permitted. For instance, expressions
       'flower ,,,100,,2' or 'flower ,' are correct.

  - Most of the existing commands in G'MIC are actually defined as custom commands.

  - A user can easily add its own custom commands to the G'MIC interpreter (see section
     'Adding custom commands' for more details). New builtin commands cannot be added
     (unless you modify the G'MIC interpreter source code and recompile it).
 7. Input/output properties
  - G'MIC is able to read/write most of the classical image file formats, including:

    . 2D grayscale/color files: .png, .jpeg, .gif, .pnm, .tif, .bmp, ...
    . 3D volumetric files: .dcm, .hdr, .nii, .pan, .inr, .pnk, ...
    . video files: .mpeg, .avi, .mov, .ogg, .flv, ...
    . Generic ascii or binary data files: .gmz, .cimg, .cimgz, .dlm, .asc, .pfm, .raw, .txt, .h.
    . 3D object files: .off.

  - When dealing with color images, G'MIC generally reads, writes and displays data using the usual
     sRGB color space.

  - G'MIC is able to manage 3D objects that may be read from files or generated by G'MIC commands.
     A 3D object is stored as a one-column scalar image containing the object data, in the
     following order: { magic_number; sizes; vertices; primitives; colors; opacities }.
     These 3D representations can be then processed as regular images.
     (see command 'split3d' for accessing each of these 3D object data separately).

  - Be aware that usual file formats may be sometimes not adapted to store all the available image
     data, since G'MIC uses float-valued image buffers. For instance, saving an image that was
     initially loaded as a 16bits/channel image, as a .jpg file will result in a loss of
     information. Use the G'MIC-specific file extension .gmz to ensure that all data
     precision is preserved when saving images.

  - Sometimes, file options may/must be set for file formats:

    . Video files: Only sub-frames of an image sequence may be loaded, using the input expression
       'filename.ext,[first_frame[,last_frame[,step]]]'. Set 'last_frame==-1' to tell it must be
       the last frame of the video. Set 'step' to 0 to force an opened video file to be
       opened/closed. Output framerate and codec can be also set by using the output expression
       'filename.avi,_fps,_codec,_keep_open={ 0 | 1 }'. 'codec' is a 4-char string
       (see http://www.fourcc.org/codecs.php) or '0' for the default codec. 'keep_open'
       tells if the output video file must be kept open for appending new frames afterwards.

    . .cimg[z] files: Only crops and sub-images of .cimg files can be loaded, using the input
      expressions 'filename.cimg,N0,N1', 'filename.cimg,N0,N1,x0,x1',
      'filename.cimg,N0,N1,x0,y0,x1,y1', 'filename.cimg,N0,N1,x0,y0,z0,x1,y1,z1' or
      'filename.cimg,N0,N1,x0,y0,z0,c0,x1,y1,z1,c1'.
      Specifying '-1' for one coordinates stands for the maximum possible value. Output expression
      'filename.cimg[z][,datatype]' can be used to force the output pixel type. 'datatype' can be
      { auto | uchar | char | ushort | short | uint | int | uint64 | int64 | float | double }.

    . .raw binary files: Image dimensions and input pixel type may be specified when loading .raw
       files with input expression
       'filename.raw[,datatype][,width][,height[,depth[,dim[,offset]]]]]'. If no dimensions are
       specified, the resulting image is a one-column vector with maximum possible height. Pixel
       type can also be specified with the output expression 'filename.raw[,datatype]'.
       'datatype' can be the same as for .cimg[z] files.

    . .yuv files: Image dimensions must be specified when loading, and only sub-frames of an image sequence
       may be loaded, using the input expression
       'filename.yuv,width,height[,chroma_subsampling[,first_frame[,last_frame[,step]]]'.
       'chroma_subsampling' can be { 420 | 422 | 444 }.
       When saving, chroma subsampling mode can be specified with output expression
       'filename.yuv[,chroma_subsampling]'.

    . .tiff files: Only sub-images of multi-pages tiff files can be loaded, using the input
       expression 'filename.tif,_first_frame,_last_frame,_step'.
       Output expression 'filename.tiff,_datatype,_compression,_force_multipage,_use_bigtiff' can
       be used to specify the output pixel type, as well as the compression method.
       'datatype' can be the same as for .cimg[z] files. 'compression' can be
       { none (default) | lzw | jpeg }. 'force_multipage can be { 0=no (default) | 1=yes }.
       'use_bigtiff can be { 0=no | 1=yes (default) }.

    . .gif files: Animated gif files can be saved, using the input expression
       'filename.gif,fps>0,nb_loops'. Specify 'nb_loops=0' to get an infinite number of animation
       loops (this is the default behavior).

    . .jpeg files: The output quality may be specified (in %), using the output expression
       'filename.jpg,30' (here, to get a 30% quality output). '100' is the default.

    . .mnc files: The output header can set from another file, using the output expression
       'filename.mnc,header_template.mnc'.

    . .pan, .cpp, .hpp, .c and .h files: The output datatype can be selected with output expression
       'filename[,datatype]'. 'datatype' can be the same as for .cimg[z] files.

    . .gmic files: These filenames are assumed to be G'MIC custom commands files. Loading such a
       file will add the commands it defines to the interpreter. Debug information can be
       enabled/disabled by the input expression 'filename.gmic[,add_debug_info={ 0 | 1 }]'.

    . Inserting 'ext:' on the beginning of a filename (e.g. 'jpg:filename') forces G'MIC to
       read/write the file as it would have been done if it had the specified extension '.ext'.

  - Some input/output formats and options may not be supported, depending on the configuration
     flags that have been set during the build of the G'MIC software.
 8. Substitution rules
  - G'MIC items containing '$' or '{}' are substituted before being interpreted. Use these
     substituting expressions to access various data from the interpreter environment.

  - '$name' and '${name}' are both substituted by the value of the specified named variable
     (set previously by the item 'name=value'). If this variable has not been already set, the
     expression is substituted by the highest positive index of the named image '[name]'. If no
     image has this name, the expression is substituted by the value of the OS environment variable
     with same name (it may be thus an empty string).
     The following reserved variables are predefined by the G'MIC interpreter:

       . '$!': The current number of images in the list.
       . '$>' and '$<': The increasing/decreasing index of the latest (currently running)
          'repeat...done' loop. '$>' goes from '0' (first loop iteration) to
          'nb_iterations - 1' (last iteration). '$<' does the opposite.
       . '$/': The current call stack. Stack items are separated by slashes '/'.
       . '$|': The current value (expressed in seconds) of a millisecond precision timer.
       . '$^': The current verbosity level.
       . '$_cpus': The number of computation cores available on your machine.
       . '$_pid': The current process identifier, as an integer.
       . '$_prerelease': For pre-releases, the date of the pre-release as 'yymmdd'.
          For stable releases, this variable is set to 0.
       . '$_version': A 3-digits number telling about the current version of the G'MIC interpreter
          (e.g. '272').
       . '$_vt100': Set to 1 if colored text output is allowed on the console.
          Otherwise, set to 0
       . '$_path_rc': The path to the G'MIC folder used to store resources and configuration files
         (its value is OS-dependent).
       . '$_path_user': The path to the G'MIC user file .gmic or user.gmic
          (its value is OS-dependent).

  - '$$name' and '$${name}' are both substituted by the G'MIC script code of the specified named
     custom command, or by an empty string if no custom command with specified name exists.

  - '${"-pipeline"}' is substituted by the status value after the execution of the specified
     G'MIC pipeline (see command 'status'). Expression '${}' thus stands for the
     current status value.

  - '{``string}' (starting with two backquotes) is substituted by a double-quoted version of the
     specified string.

  - '{/string}' is substituted by the escaped version of the specified string.

  - '{'string'}' (between single quotes) is substituted by the sequence of ascii codes that compose
     the specified string, separated by commas ','. For instance, item '{'foo'}' is substituted
     by '102,111,111'.

  - '{image,feature}' is substituted by a specific feature of the image [image]. 'image' can be
     either an image number or an image name. It can be also eluded, in which case, the last image
     '[-1]' of the list is considered for the requested feature.
     Specified 'feature' can be one of:

       . 'b': The image basename (i.e. filename without the folder path nor extension).
       . 'f': The image folder name.
       . 'n': The image name or filename (if the image has been read from a file).
       . 't': The text string from the image values regarded as ascii codes.
       . 'x': The image extension (i.e the characters after the last '.' in the image name).
       . '^ : The sequence of all image values, separated by commas ','.
       . '@subset': The sequence of image values corresponding to the specified subset, and
          separated by commas ','.
       . Any other 'feature' is considered as a mathematical expression associated to the image
          [image] and is substituted by the result of its evaluation (float value). For instance,
          expression '{0,w+h}' is substituted by the sum of the width and height of the first image
          (see section 'Mathematical expressions' for more details). If a mathematical expression
          starts with an underscore '_', the resulting value is truncated to a readable format.
          For instance, item '{_pi}' is substituted by '3.14159' (while '{pi}'
           is substituted by '3.141592653589793').
       . A 'feature' delimited by backquotes is replaced by a string whose ascii codes correspond
          to the list of values resulting from the evaluation of the specified mathematical
          expression. For instance, item '{`[102,111,111]`}' is substituted by 'foo' and item
          '{`vector8(65)`}' by 'AAAAAAAA'.

  - '{*}' is substituted by the visibility state of the instant display window [0]
     (can be { 0=closed | 1=visible }).

  - '{*,feature1,...,featureN}' or '{*index,feature1,...,featureN}' is substituted by a specific
      set of features of the instant display window #0 (or #index, if specified).
      Requested 'features' can be:

       . 'w': display width (i.e. width of the display area managed by the window).
       . 'h': display height (i.e. height of the display area managed by the window).
       . 'wh': display width x display height.
       . 'd': window width (i.e. width of the window widget).
       . 'e': window height (i.e. height of the window widget).
       . 'de': window width x window height.
       . 'u': screen width (actually independent on the window size).
       . 'v': screen height (actually independent on the window size).
       . 'uv': screen width x screen height.
       . 'n': current normalization type of the instant display.
       . 't': window title of the instant display.
       . 'x': X-coordinate of the mouse position (or -1, if outside the display area).
       . 'y': Y-coordinate of the mouse position (or -1, if outside the display area).
       . 'b': state of the mouse buttons { 1=left-but. | 2=right-but. | 4=middle-but. }.
       . 'o': state of the mouse wheel.
       . 'k': decimal code of the pressed key if any, 0 otherwise.
       . 'c': boolean (0 or 1) telling if the instant display has been closed recently.
       . 'r': boolean telling if the instant display has been resized recently.
       . 'm': boolean telling if the instant display has been moved recently.
       . Any other 'feature' stands for a keycode name (in capital letters), and is substituted
          by a boolean describing the current key state { 0=pressed | 1=released }.
       . You can also prepend a hyphen '-' to a 'feature' (that supports it) to flush the
          corresponding event immediately after reading its state (works for keys, mouse and
          window events).

  - Item substitution is never performed in items between double quotes. One must break the quotes
    to enable substitution if needed, as in '"3+8 kg = "{3+8}" kg"'. Using double quotes is then
    a convenient way to disable the substitutions mechanism in items, when necessary.

  - One can also disable the substitution mechanism on items outside double quotes, by escaping the
     '{','}' or '$' characters, as in '\{3+4\ doesn't\ evaluate'.
 9. Mathematical expressions
  - G'MIC has an embedded mathematical parser. It is used to evaluate (possibly complex) expressions
     inside braces '{}', or formulas in commands that may take one as an argument (e.g. 'fill').

  - When the context allows it, a formula is evaluated for each pixel of the selected images
     (e.g. 'fill').

  - A math expression may return a scalar or vector-valued result (with a fixed number of
     components).

  - The mathematical parser understands the following set of functions, operators and variables:

    _ Usual operators: || (logical or), && (logical and), | (bitwise or), & (bitwise and),
       !=, ==, <=, >=, <, >, << (left bitwise shift), >> (right bitwise shift), -, +, *, /,
       % (modulo), ^ (power), ! (logical not), ~ (bitwise not),
       ++, --, +=, -=, *=, /=, %=, &=, |=, ^=, >>=, <<= (in-place operators).

    _ Usual math functions: abs(), acos(), acosh(), arg(), argkth(), argmax(), argmin(), asin(),
       asinh(), atan(), atan2(), atanh(), avg(), bool(), cbrt(), ceil(), cos(), cosh(), cut(), exp(), fact(),
       fibo(), floor(), gauss(), int(), isnan(), isnum(), isinf(), isint(), isbool(), isexpr(), isfile(), isdir(),
       isin(), kth(), log(), log2(), log10(), max(), med(), min(), narg(), prod(), rol() (left bit rotation),
       ror() (right bit rotation), round(), sign(), sin(), sinc(), sinh(), sqrt(), std(),
       srand(_seed), sum(), tan(), tanh(), var(), xor().

       . 'atan2(y,x)' is the version of 'atan()' with two arguments 'y' and 'x' (as in C/C++).
       . 'permut(k,n,with_order)' computes the number of permutations of k objects from a set of
          n objects.
       . 'gauss(x,_sigma,_is_normalized)' returns 'exp(-x^2/(2*s^2))/(is_normalized?sqrt(2*pi*sigma^2):1)'.
       . 'cut(value,min,max)' returns value if it is in range [min,max], or min or max otherwise.
       . 'narg(a_1,...,a_N)' returns the number of specified arguments (here, N).
       . 'arg(i,a_1,..,a_N)' returns the ith argument a_i.
       . 'isnum()', 'isnan()', 'isinf()', 'isint()', 'isbool()' test the type of the given
          number or expression, and return 0 (false) or 1 (true).
       . 'isfile('path')' (resp. 'isdir('path')') returns 0 (false) or 1 (true) whether its string argument is a
          path to an existing file (resp. to a directory) or not.
       . 'isin(v,a_1,...,a_n)' returns 0 (false) or 1 (true) whether the first value 'v' appears
          in the set of other values 'a_i'.
       . 'argmin()', 'argmax()', 'avg()', 'kth()', 'max()', 'med()', 'min()', 'std()', 'sum()'
          and 'var()' can be called with an arbitrary number of scalar/vector arguments.
       . 'round(value,rounding_value,direction)' returns a rounded value. 'direction' can be
          { -1=to-lowest | 0=to-nearest | 1=to-highest }.

    _ Variable names below are pre-defined. They can be overridden.

       . 'l': length of the associated list of images.
       . 'w': width of the associated image, if any (0 otherwise).
       . 'h': height of the associated image, if any (0 otherwise).
       . 'd': depth of the associated image, if any (0 otherwise).
       . 's': spectrum of the associated image, if any (0 otherwise).
       . 'r': shared state of the associated image, if any (0 otherwise).
       . 'wh': shortcut for width x height.
       . 'whd': shortcut for width x height x depth.
       . 'whds': shortcut for width x height x depth x spectrum (i.e. number of image values).
       . 'im','iM','ia','iv','is','ip','ic': Respectively the minimum, maximum, average,
          variance, sum, product and median value of the associated image, if any (0 otherwise).
       . 'xm','ym','zm','cm': The pixel coordinates of the minimum value
          in the associated image, if any (0 otherwise).
       . 'xM','yM','zM','cM': The pixel coordinates of the maximum value
          in the associated image, if any (0 otherwise).
       . All these variables are considered as constant values by the math parser (for optimization
          purposes) which is indeed the case most of the time. Anyway, this might not be the case,
          if function 'resize(#ind,..)' is used in the math expression.
          If so, it is safer to invoke functions 'l()', 'w(_#ind)', 'h(_#ind)', ... 's(_#ind)'
          and 'ic(_#ind)' instead of the corresponding named variables.
       . 'i': current processed pixel value (i.e. value located at (x,y,z,c)) in the associated
          image, if any (0 otherwise).
       . 'iN': Nth channel value of current processed pixel (i.e. value located at (x,y,z,N)) in
          the associated image, if any (0 otherwise). 'N' must be an integer in range [0,9].
       . 'R','G','B' and 'A' are equivalent to 'i0', 'i1', 'i2' and 'i3' respectively.
       . 'I': current vector-valued processed pixel in the associated image, if any (0 otherwise).
          The number of vector components is equal to the number of image channels
          (e.g. I = [ R,G,B ] for a RGB image).
       . You may add '#ind' to any of the variable name above to retrieve the information for any
          numbered image [ind] of the list (when this makes sense). For instance 'ia#0' denotes
          the average value of the first image of the list).
       . 'x': current processed column of the associated image, if any (0 otherwise).
       . 'y': current processed row of the associated image, if any (0 otherwise).
       . 'z': current processed slice of the associated image, if any (0 otherwise).
       . 'c': current processed channel of the associated image, if any (0 otherwise).
       . 't': thread id when an expression is evaluated with multiple threads (0 means
          'master thread').
       . 'e': value of e, i.e. 2.71828...
       . 'pi': value of pi, i.e. 3.1415926...
       . 'u': a random value between [0,1], following a uniform distribution.
       . 'g': a random value, following a gaussian distribution of variance 1
          (roughly in [-6,6]).
       . 'interpolation': value of the default interpolation mode used when reading pixel values
           with the pixel access operators (i.e. when the interpolation argument is not explicitly
           specified, see below for more details on pixel access operators). Its initial default
           value is 0.
       . 'boundary': value of the default boundary conditions used when reading pixel values with
           the pixel access operators (i.e. when the boundary condition argument is not explicitly
           specified, see below for more details on pixel access operators). Its initial default
           value is 0.

    _ Vector calculus: Most operators are also able to work with vector-valued elements.

       . '[ a0,a1,...,aN-1 ]' defines a N-dimensional vector with scalar coefficients ak.
       . 'vectorN(a0,a1,,...,aN-1)' does the same, with the ak being repeated periodically if
          only a few are specified.
       . 'vector(#N,a0,a1,,...,aN-1)' does the same, and can be used for any constant expression N.
       . In previous expressions, the ak can be vectors themselves, to be concatenated into a
          single vector.
       . The scalar element ak of a vector X is retrieved by 'X[k]'.
       . The sub-vector [ X[p],X[p+s]...X[p+s*(q-1)] ] (of size q) of a vector X
          is retrieved by 'X[p,q,s]'.
       . Equality/inequality comparisons between two vectors is done with operators '==' and '!='.
       . Some vector-specific functions can be used on vector values:
         'cross(X,Y)' (cross product), 'dot(X,Y)' (dot product), 'size(X)' (vector dimension),
         'sort(X,_is_increasing,_chunk_size)' (sorting values), 'reverse(A)' (reverse order of
         components), 'shift(A,_length,_boundary_conditions)' and
         'same(A,B,_nb_vals,_is_case_sensitive)' (vector equality test).
       . Function 'normP(u1,...,un)' computes the LP-norm of the specified vector
          (P being an unsigned integer constant or 'inf'). If P is omitted, the L2 norm is used.
       . Function 'resize(A,size,_interpolation,_boundary_conditions)' returns a resized version of
          a vector 'A' with specified interpolation mode. 'interpolation' can be { -1=none
          (memory content) | 0=none | 1=nearest | 2=average | 3=linear | 4=grid | 5=bicubic |
          6=lanczos }, and 'boundary_conditions' can be { 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }.
       . Function 'find(A,B,_is_forward,_starting_index)' returns the index where sub-vector B
          appears in vector A, (or -1 if B is not found in A). Argument A can be also replaced by
          an image index #ind.
       . A 2-dimensional vector may be seen as a complex number and used in those particular
          functions/operators:
          '**' (complex multiplication), '//' (complex division), '^^' (complex exponentiation),
          '**=' (complex self-multiplication), '//=' (complex self-division), '^^=' (complex
          self-exponentiation), 'cabs()' (complex modulus), 'carg()' (complex argument), 'cconj()'
          (complex conjugate), 'cexp()' (complex exponential) and 'clog()' (complex logarithm).
       . A MN-dimensional vector may be seen as a M x N matrix and used in those
          particular functions/operators:
          '*' (matrix-vector multiplication), 'det(A)' (determinant), 'diag(V)' (diagonal matrix
          from a vector), 'eig(A)' (eigenvalues/eigenvectors), 'eye(n)' (n x n identity matrix),
          'inv(A)' (matrix inverse), 'mul(A,B,_nb_colsB)' (matrix-matrix multiplication),
          'pseudoinv(A,_nb_colsA)', 'rot(u,v,w,angle)' (3D rotation matrix), 'rot(angle)' (2D
          rotation matrix), 'solve(A,B,_nb_colsB)' (least-square solver of linear system A.X = B),
          'svd(A,_nb_colsA)' (singular value decomposition), 'trace(A)' (matrix trace) and
          'transp(A,nb_colsA)' (matrix transpose). Argument 'nb_colsB' may be omitted if it is
          equal to 1.
       . Specifying a vector-valued math expression as an argument of a command that operates on
          image values (e.g. 'fill') modifies the whole spectrum range of the processed image(s),
          for each spatial coordinates (x,y,z). The command does not loop over the C-axis in this
          case.

    _ String manipulation: Character strings are defined and managed as vectors objects.
       Dedicated functions and initializers to manage strings are

       . [ 'string' ] and 'string' define a vector whose values are the ascii codes of the
          specified character string (e.g. 'foo' is equal to [ 102,111,111 ]).
       . _'character' returns the (scalar) ascii code of the specified character (e.g. _'A' is
          equal to 65).
       . A special case happens for empty strings: Values of both expressions [ '' ] and '' are 0.
       . Functions 'lowercase()' and 'uppercase()' return string with all string characters
          lowercased or uppercased.
       . Function 'stov(str,_starting_index,_is_strict)' parses specified string 'str' and
          returns the value contained in it.
       . Function 'vtos(expr,_nb_digits,_siz)' returns a vector of size 'siz' which contains
          the ascii representation of values described by expression 'expr'.
          'nb_digits' can be { -1=auto-reduced | 0=all | >0=max number of digits }.
       . Function 'echo(str1,str2,...,strN)' prints the concatenation of given string arguments
          on the console.
       . Function 'cats(str1,str2,...,strN,siz)' returns the concatenation of given string arguments
          as a new vector of size 'siz'.

    _ Special operators can be used:

       . ';': expression separator. The returned value is always the last encountered expression.
          For instance expression '1;2;pi' is evaluated as 'pi'.
       . '=': variable assignment. Variables in mathematical parser can only refer to numerical
          values (vectors or scalars). Variable names are case-sensitive. Use this operator in
          conjunction with ';' to define more complex evaluable expressions, such as
          't=cos(x);3*t^2+2*t+1'.
          These variables remain local to the mathematical parser and cannot be accessed outside
           the evaluated expression.
       . Variables defined in math parser may have a constant property, by specifying keyword 'const'
          before the variable name (e.g. 'const foo = pi/4;'). The value set to such a variable must
          be indeed a constant scalar. Constant variables allows certain types of optimizations in
          the math JIT compiler.

    _ The following specific functions are also defined:

       . 'u(max)' or 'u(min,max)': return a random value between [0,max] or [min,max], following
          a uniform distribution.
       . 'i(_a,_b,_c,_d,_interpolation_type,_boundary_conditions)': return the value of the pixel
          located at position (a,b,c,d) in the associated image, if any (0 otherwise).
          'interpolation_type' can be { 0=nearest neighbor | 1=linear | 2=cubic }.
          'boundary_conditions' can be { 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }.
          Omitted coordinates are replaced by their default values which are respectively
          x, y, z, c, interpolation and boundary.
          For instance command 'fill 0.5*(i(x+1)-i(x-1))' will estimate the X-derivative of an
          image with a classical finite difference scheme.
       . 'j(_dx,_dy,_dz,_dc,_interpolation_type,_boundary_conditions)' does the same for the pixel
          located at position (x+dx,y+dy,z+dz,c+dc) (pixel access relative to the current
          coordinates).
       . 'i[offset,_boundary_conditions]' returns the value of the pixel located at specified
          'offset' in the associated image buffer (or 0 if offset is out-of-bounds).
       . 'j[offset,_boundary_conditions]' does the same for an offset relative to the current pixel
          coordinates (x,y,z,c).
       . 'i(#ind,_x,_y,_z,_c,_interpolation,_boundary_conditions)',
          'j(#ind,_dx,_dy,_dz,_dc,_interpolation,_boundary_conditions)',
          'i[#ind,offset,_boundary_conditions]' and 'i[offset,_boundary_conditions]' are similar
          expressions used to access pixel values for any numbered image [ind] of the list.
       . 'I/J[offset,_boundary_conditions]' and 'I/J(#ind,_x,_y,_z,_interpolation,_boundary_conditions)' do
          the same as 'i/j[offset,_boundary_conditions]' and
          'i/j(#ind,_x,_y,_z,_c,_interpolation,_boundary_conditions)' but return a vector instead of a scalar
          (e.g. a vector [ R,G,B ] for a pixel at (a,b,c) in a color image).
       . 'sort(#ind,_is_increasing,_axis)' sorts the values in the specified image [ind].
       . 'crop(_#ind,_x,_y,_z,_c,_dx,_dy,_dz,_dc,_boundary_conditions)' returns a vector whose values come
          from the cropped region of image [ind] (or from default image selected if 'ind' is not
          specified). Cropped region starts from point (x,y,z,c) and has a size of
          dx x dy x dz x dc. Arguments for coordinates and sizes can be omitted if they are not
          ambiguous (e.g. 'crop(#ind,x,y,dx,dy)' is a valid invocation of this function).
       . 'draw(_#ind,S,x,y,z,c,dx,_dy,_dz,_dc,_opacity,_M,_max_M)' draws a sprite S in image [ind]
          (or in default image selected if 'ind' is not specified) at coordinates (x,y,z,c).
          The size of the sprite dx x dy x dz x dc must be specified. You can also specify a
          corresponding opacity mask M if its size matches S.
       . 'polygon(_#ind,nb_vertices,coords,_opacity,_color)' draws a filled polygon in image [ind]
          (or in default image selected if 'ind' is not specified) at specified coordinates.
          It draws a single line if 'nb_vertices' is set to 2.
       . 'polygon(_#ind,-nb_vertices,coords,_opacity,_pattern,_color)' draws a outlined polygon in image [ind]
          (or in default image selected if 'ind' is not specified) at specified coordinates and with
          specified line pattern. It draws a single line if 'nb_vertices' is set to 2.
       . 'ellipse(_#ind,xc,yc,radius1,_radius2,_angle,_opacity,_color)' draws a filled ellipse in image [ind]
          (or in default image selected if 'ind' is not specified) with specified coordinates.
       . 'ellipse(_#ind,xc,yc,-radius1,-_radius2,_angle,_opacity,_pattern,_color)' draws an outlined
          ellipse in image [ind] (or in default image selected if 'ind' is not specified).
       . 'resize(#ind,w,_h,_d,_s,_interp,_boundary_conditions,_cx,_cy,_cz,_cc)' resizes an image of the
          associated list with specified dimension and interpolation method. When using this,
          function, you should consider retrieving the (non-constant) image dimensions using the
          dynamic functions 'w(_#ind)', 'h(_#ind)', 'd(_#ind)', 's(_#ind)', 'wh(_#ind)',
          'whd(_#ind)' and 'whds(_#ind)' instead of the corresponding constant variables.
       . 'if(condition,expr_then,_expr_else)': return value of 'expr_then' or 'expr_else',
          depending on the value of 'condition' (0=false, other=true). 'expr_else' can be omitted
          in which case 0 is returned if the condition does not hold. Using the ternary operator
          'condition?expr_then[:expr_else]' gives an equivalent expression.
          For instance, G'MIC commands 'fill if(x%10==0,255,i)' and 'fill x%10?i:255'
          both draw blank vertical lines on every 10th column of an image.
       . 'do(expression,_condition)' repeats the evaluation of 'expression' until 'condition'
          vanishes (or until 'expression' vanishes if no 'condition' is specified). For instance,
          the expression: 'if(N<2,N,n=N-1;F0=0;F1=1;do(F2=F0+F1;F0=F1;F1=F2,n=n-1))' returns
          the Nth value of the Fibonacci sequence, for N>=0 (e.g., 46368 for N=24).
          'do(expression,condition)' always evaluates the specified expression at least once,
          then check for the loop condition. When done, it returns the last value of 'expression'.
       . 'for(init,condition,_procedure,body)' first evaluates the expression 'init', then
          iteratively evaluates 'body' (followed by 'procedure' if specified) while 'condition'
          is verified (i.e. not zero). It may happen that no iteration is done, in which case the
          function returns nan. Otherwise, it returns the last value of 'body'.
          For instance, the expression: 'if(N<2,N,for(n=N;F0=0;F1=1,n=n-1,F2=F0+F1;F0=F1;F1=F2))'
          returns the Nth value of the Fibonacci sequence, for N>=0 (e.g., 46368 for N=24).
       . 'while(condition,expression)' is exactly the same as 'for(init,condition,expression)'
          without the specification of an initializing expression.
       . 'break()' and 'continue()' respectively breaks and continues the current running bloc
          (loop, init or main environment).
       . 'fsize('filename')' returns the size of the specified 'filename' (or '-1' if file does not exist).
       . 'date(attr,'path')' returns the date attribute for the given 'path' (file or directory),
          with 'attr' being { 0=year | 1=month | 2=day | 3=day of week | 4=hour | 5=minute |
          6=second }, or a vector of those values.
       . 'date(_attr)' returns the specified attribute for the current (locale) date.
       . 'print(expr1,expr2,...)' or 'print(#ind)' prints the value of the specified expressions
          (or image information) on the console, and returns the value of the last expression
          (or nan in case of an image). Function 'prints(expr)' also prints the string composed
          of the ascii characters defined by the vector-valued expression (e.g. 'prints('Hello')').
       . 'debug(expression)' prints detailed debug information about the sequence of operations done
          by the math parser to evaluate the expression (and returns its value).
       . 'display(_X,_w,_h,_d,_s)' or 'display(#ind)' display the contents of the vector 'X'
          (or specified image) and wait for user events. if no arguments are provided, a memory
          snapshot of the math parser environment is displayed instead.
       . 'begin(expression)' and 'end(expression)' evaluates the specified expressions only once,
          respectively at the beginning and end of the evaluation procedure, and this,
          even when multiple evaluations are required (e.g. in 'fill ">begin(foo = 0); ++foo"').
       . 'copy(dest,src,_nb_elts,_inc_d,_inc_s,_opacity)' copies an entire memory block of 'nb_elts'
          elements starting from a source value 'src' to a specified destination 'dest', with
          increments defined by 'inc_d' and 'inc_s' respectively for the destination and source
          pointers.
       . 'stats(_#ind)' returns the statistics vector of the running image '[ind]', i.e the vector
          [ im,iM,ia,iv,xm,ym,zm,cm,xM,yM,zM,cM,is,ip ] (14 values).
       . 'unref(a,b,...)' destroys references to the named variable given as arguments.
       . 'breakpoint()' inserts a possible computation breakpoint (not supported by the cli interface).
       . '_(expr)' just ignores its arguments (mainly useful for debugging).
       . 'ext('pipeline')' executes the specified G'MIC pipeline as if it was called outside
          the currently evaluated expression.
       . 'correlate(I,wI,hI,dI,sI,K,wK,hK,dK,sK,_boundary_conditions,_is_normalized,_channel_mode,
                    _xcenter,_ycenter,_zcenter,_xstart,_ystart,_zstart,_xend,_yend,_zend,
                    _xstride,_ystride,_zstride,_xdilation,_ydilation,_zdilation)'
           returns the correlation, unrolled as a vector, of the wI x hI x dI x sI-sized image I with
           the wK x hK x dK x sK-sized kernel K (the meaning of the other arguments are the same as in
           command 'correlate'). Similar function 'convolve(...)' is also defined for computing
           the convolution between I and K.

    - User-defined macros:

       . Custom macro functions can be defined in a math expression, using the assignment operator
          '=', e.g. 'foo(x,y) = cos(x + y); result = foo(1,2) + foo(2,3)'.
       . Trying to override a built-in function (e.g. 'abs()') has no effect.
       . Overloading macros with different number of arguments is possible. Re-defining a
          previously defined macro with the same number of arguments discards its previous
          definition.
       . Macro functions are indeed processed as macros by the mathematical evaluator. You should
          avoid invoking them with arguments that are themselves results of assignments or
          self-operations. For instance, 'foo(x) = x + x; z = 0; foo(++z)' returns '4' rather
          than expected value '2'.
       . When substituted, macro arguments are placed inside parentheses, except if a number sign
          '#' is located just before or after the argument name. For instance, expression
          'foo(x,y) = x*y; foo(1+2,3)' returns '9' (being substituted as '(1+2)*(3)'), while
          expression 'foo(x,y) = x#*y#; foo(1+2,3)' returns '7' (being substituted as '1+2*3').
       . Number signs appearing between macro arguments function actually count for 'empty'
          separators. They may be used to force the substitution of macro arguments in unusual
          places, e.g. as in 'str(N) = ['I like N#'];'.

    - Multi-threaded and in-place evaluation:

       . If your image data are large enough and you have several CPUs available, it is likely that
          the math expression passed to a 'fill' or 'input' command is evaluated in parallel,
          using multiple computation threads.
       . Starting an expression with ':' or '*' forces the evaluations required for an image to be
          run in parallel, even if the amount of data to process is small (beware, it may be slower
          to evaluate in this case!). Specify ':' (instead of '*') to avoid possible image copy
          done before evaluating the expression (this saves memory, but do this only if you are
          sure this step is not required!)
       . If the specified expression starts with '>' or '<', the pixel access operators
          'i(), i[], j()' and 'j[]' return values of the image being currently modified,
          in forward ('>') or backward ('<') order. The multi-threading evaluation of the
          expression is also disabled in this case.
       . Function 'critical(operands)' forces the execution of the given operands in a single thread at a
          time.

    _ Expressions 'i(_#ind,x,_y,_z,_c)=value', 'j(_#ind,x,_y,_z,_c)=value', 'i[_#ind,offset]=value'
       and 'j[_#ind,offset]=value' set a pixel value at a different location than the running one
       in the image [ind] (or in the associated image if argument '#ind' is omitted), either with
       global coordinates/offsets (with 'i(...)' and 'i[...]'), or relatively to the current
       position (x,y,z,c) (with 'j(...)' and 'j[...]'). These expressions always return 'value'.

  - The last image of the list is always associated to the evaluations of '{expressions}',
     e.g. G'MIC sequence '256,128 fill {w}' will create a 256x128 image filled with value 256.
 10. Image and data viewers
  - G'MIC has some very handy embedded visualization modules, for 1D signals (command 'plot'),
     1D/2D/3D images (command 'display') and 3D objects (command 'display3d'). It manages
     interactive views of the selected image data.

  - The following actions are available in the interactive viewers:

    . (mousewheel): Zoom in/out.
    . ESC: Close window.
    . CTRL+D: Increase window size.
    . CTRL+C: Decrease window size.
    . CTRL+R: Reset window size.
    . CTRL+F: Toggle fullscreen mode.
    . CTRL+S: Save current view as a numbered file 'gmic_xxxx.ext'.
    . CTRL+O: Save copy of the viewed data, as a numbered file 'gmic_xxxx.ext'.

  - Actions specific to the 1D/2D image viewer (command 'display') are:

    . Left mouse button: Create an image selection and zoom into it.
    . Middle mouse button, or CTRL+left mouse button: Move image.
    . Mouse wheel or PADD+/-: Zoom in/out.
    . Arrow keys: Move image left/right/up/down.
    . CTRL+A: Enable/disable transparency (show alpha channel).
    . CTRL+N: Change normalization mode (can be 'none', 'normal' or 'channel-by-channel').
    . CTRL+SPACE: Reset view.
    . CTRL+X: Show/hide axes.
    . CTRL+Z: Hold/release aspect ratio.

  - Actions specific to the 3D volumetric image viewer (command 'display') are:

    . CTRL+P: Play z-stack of frames as a movie.
    . CTRL+V: Show/hide 3D view on bottom right zone.
    . CTRL+X: Show/hide axes.
    . CTRL+(mousewheel): Go up/down.
    . SHIFT+(mousewheel): Go left/right.
    . Numeric PAD: Zoom in/out (+/-) and move through zoomed image (digits).
    . BACKSPACE: Reset zoom scale.

  - Actions specific to the 3D object viewer (command 'display3d') are:

    . (mouse)+(left mouse button): Rotate 3D object.
    . (mouse)+(right mouse button): Zoom 3D object.
    . (mouse)+(middle mouse button): Shift 3D object.
    . CTRL+F1 ... CTRL+F6: Toggle between different 3D rendering modes.
    . CTRL+G: Save 3D object, as numbered file 'gmic_xxxx.off'.
    . CTRL+T: Switch between single/double-sided 3D modes.
    . CTRL+X: Show/hide 3D axes.
    . CTRL+Z: Enable/disable z-buffered rendering.
 11. Adding custom commands
  - New custom commands can be added by the user, through the use of G'MIC custom commands files.

  - A command file is a simple ascii text file, where each line starts either by
     'command_name: command_definition' or 'command_definition (continuation)'.

  - At startup, G'MIC automatically includes user's command file $HOME/.gmic (on Unix) or
     %APPDATA%/user.gmic (on Windows). The CLI tool 'gmic' automatically runs the command
     'cli_start' if defined.

  - Custom command names must use character set [a-zA-Z0-9_] and cannot start with a number.

  - Any ' # comment' expression found in a custom commands file is discarded by the G'MIC parser,
     wherever it is located in a line.

  - In a custom command, the following $-expressions are recognized and substituted:

    . '$*' is substituted by a copy of the specified string of arguments.
    . '$"*"' is substituted by a copy of the specified string of arguments, each being
       double-quoted.
    . '$#' is substituted by the maximum index of known arguments (either specified by the user
       or set to a default value in the custom command).
    . '$[]' is substituted by the list of selected image indices that have been specified during the
       command invocation.
    . '$?' is substituted by a printable version of '$[]' to be used in command descriptions.
    . '$i' and '${i}' are both substituted by the i^th specified argument. Negative indices such as
       '${-j}' are allowed and refer to the j^th latest argument. '$0' is substituted
       by the custom command name.
    . '${i=default}' is substituted by the value of $i (if defined) or by its new value set to
        'default' otherwise ('default' may be a $-expression as well).
    . '${subset}' is substituted by the argument values (separated by commas ',') of a specified
       argument subset. For instance expression '${2--2}' is substitued by all specified command
       arguments except the first and the last one. Expression '${^0}' is then substituted by all
       arguments of the invoked command (eq. to '$*' if all specified arguments have indeed a
       value).
    . '$=var' is substituted by the set of instructions that will assign each argument $i to the
       named variable 'var$i' (for i in [0...$#]). This is particularly useful when a custom
       command want to manage variable numbers of arguments. Variables names must use character set
       [a-zA-Z0-9_] and cannot start with a number.

  - These particular $-expressions for custom commands are always substituted, even in
     double-quoted items or when the dollar sign '$' is escaped with a backslash '\'. To avoid
     substitution, place an empty double quoted string just after the '$' (as in '$""1').

  - Specifying arguments may be skipped when invoking a custom command, by replacing them by commas
     ',' as in expression 'flower ,,3'. Omitted arguments are set to their default values, which
     must be thus explicitly defined in the code of the corresponding custom command (using
     default argument expressions as '${1=default}').

  - If one numbered argument required by a custom command misses a value, an error is thrown by the
     G'MIC interpreter.
 12. List of commands
   All available G'MIC commands are listed below, classified by themes. When several choices of
   command arguments are possible, they appear separated by '|'. An argument specified inside '[]'
   or starting by '_' is optional except when standing for an existing image [image], where 'image'
   can be either an index number or an image name. In this case, the '[]' characters are mandatory
   when writing the item. A command marked with '(+)' is one of the builtin commands. Note also
   that all images that serve as illustrations in this reference documentation are normalized in [0,255]
   before being displayed. You may need to do this explicitly (command 'normalize 0,255') if you
   want to save and view images with the same aspect than those illustrated in the example codes.
 ** Global Options:
    debug (+):
        Activate debug mode.
        When activated, the G'MIC interpreter becomes very verbose and outputs additional log
        messages about its internal state on the standard output (stdout).
        This option is useful for developers or to report possible bugs of the interpreter.
    help:
        command |
        (no arg)
        Display help (optionally for specified command only) and exit.
        (eq. to 'h').
    version:
        Display current version number on stdout.
 ** Input / Output:
    camera (+):
        _camera_index>=0,_nb_frames>0,_skip_frames>=0,_capture_width>=0,
          _capture_height>=0
        Insert one or several frames from specified camera.
        When 'nb_frames==0', the camera stream is released instead of capturing new images.

        Default values: 'camera_index=0' (default camera), 'nb_frames=1', 'skip_frames=0' and
          'capture_width=capture_height=0' (default size).
    clut:
        "clut_name",_resolution>0,_cut_and_round={ 0=no | 1=yes }
        Insert one of the 763 pre-defined CLUTs at the end of the image list.
        'clut_name' can be { 2-strip-process | 60s | 60s_faded | 60s_faded_alt | action_magenta_01 |
          action_red_01 | adventure_1453 | agfa_apx_100 | agfa_apx_25 | agfa_precisa_100 |
          agfa_ultra_color_100 | agfa_vista_200 | agressive_highligjtes_recovery_5 | alien_green |
          analogfx_anno_1870_color | analogfx_old_style_i | analogfx_old_style_ii |
          analogfx_old_style_iii | analogfx_sepia_color | analogfx_soft_sepia_i | analogfx_soft_sepia_ii |
           anime | apocalypse_this_very_moment | aqua | aqua_and_orange_dark | arabica_12 | ava_614 |
          avalanche | azrael_93 | bboyz_2 | berlin_sky | black_and_white | black_star | blade_runner |
          bleach_bypass | bleachbypass_1 | bleachbypass_2 | bleachbypass_3 | bleachbypass_4 |
          bleech_bypass_green | bleech_bypass_yellow_01 | blue_dark | blue_house | blue_ice | blue_mono |
          blue_shadows_01 | blues | bob_ford | bourbon_64 | bright_green_01 | brightgreen | brownish |
          bw_1 | bw_10 | bw_2 | bw_3 | bw_4 | bw_5 | bw_6 | bw_7 | bw_8 | bw_9 | byers_11 | candlelight |
          caribe | chemical_168 | chrome_01 | cinema | cinema_2 | cinema_3 | cinema_4 | cinema_5 |
          cinema_noir | cinematic-1 | cinematic-10 | cinematic-2 | cinematic-3 | cinematic-4 |
          cinematic-5 | cinematic-6 | cinematic-7 | cinematic-8 | cinematic-9 | cinematic_01 |
          cinematic_02 | cinematic_03 | cinematic_for_flog | city_7 | classic_teal_and_orange |
          clayton_33 | clouseau_54 | cobi_3 | coffee_44 | cold_simplicity_2 | color_rich | colorful_0209 |
           colornegative | conflict_01 | contrail_35 | contrast_with_highlights_protection |
          contrasty_afternoon | contrasty_green | crispromance | crispwarm | crispwinter |
          cross_process_cp_130 | cross_process_cp_14 | cross_process_cp_15 | cross_process_cp_16 |
          cross_process_cp_18 | cross_process_cp_3 | cross_process_cp_4 | cross_process_cp_6 | crushin |
          cubicle_99 | d_o_1 | dark_green_02 | dark_green_1 | dark_place_01 | date_39 | day_4nite |
          day_for_night | denoiser_simple_40 | desert_gold_37 | directions_23 | django_25 | domingo_145 |
          dream_1 | dream_85 | drop_green_tint_14 | dropblues | earth_tone_boost | edgyember |
          elegance_38 | eterna_for_flog | expired_fade | expired_polaroid | extreme | fade |
          fade_to_green | faded | faded_47 | faded_alt | faded_analog | faded_extreme | faded_retro_01 |
          faded_retro_02 | faded_vivid | fallcolors | faux_infrared | fgcinebasic | fgcinebright |
          fgcinecold | fgcinedrama | fgcinetealorange_1 | fgcinetealorange_2 | fgcinevibrant | fgcinewarm
          | film_0987 | film_9879 | film_high_contrast | film_print_01 | film_print_02 | filmic | flat_30
          | foggynight | folger_50 | french_comedy | frostedbeachpicnic | fuji_160c | fuji_160c_+ |
          fuji_160c_++ | fuji_160c_- | fuji_3510_constlclip | fuji_3510_constlmap | fuji_3510_cuspclip |
          fuji_3513_constlclip | fuji_3513_constlmap | fuji_3513_cuspclip | fuji_400h | fuji_400h_+ |
          fuji_400h_++ | fuji_400h_- | fuji_800z | fuji_800z_+ | fuji_800z_++ | fuji_800z_- |
          fuji_astia_100_generic | fuji_astia_100f | fuji_fp-100c | fuji_fp-100c_+ | fuji_fp-100c_++ |
          fuji_fp-100c_+++ | fuji_fp-100c_++_alt | fuji_fp-100c_- | fuji_fp-100c_-- | fuji_fp-100c_alt |
          fuji_fp-100c_cool | fuji_fp-100c_cool_+ | fuji_fp-100c_cool_++ | fuji_fp-100c_cool_- |
          fuji_fp-100c_cool_-- | fuji_fp-100c_negative | fuji_fp-100c_negative_+ | fuji_fp-100c_negative_+
          + | fuji_fp-100c_negative_+++ | fuji_fp-100c_negative_++_alt | fuji_fp-100c_negative_- |
          fuji_fp-100c_negative_-- | fuji_fp-3000b | fuji_fp-3000b_+ | fuji_fp-3000b_++ | fuji_fp-3000b_++
          + | fuji_fp-3000b_- | fuji_fp-3000b_-- | fuji_fp-3000b_hc | fuji_fp-3000b_negative |
          fuji_fp-3000b_negative_+ | fuji_fp-3000b_negative_++ | fuji_fp-3000b_negative_+++ |
          fuji_fp-3000b_negative_- | fuji_fp-3000b_negative_-- | fuji_fp-3000b_negative_early |
          fuji_fp_100c | fuji_hdr | fuji_neopan_1600 | fuji_neopan_1600_+ | fuji_neopan_1600_++ |
          fuji_neopan_1600_- | fuji_neopan_acros_100 | fuji_provia_100_generic | fuji_provia_100f |
          fuji_provia_400f | fuji_provia_400x | fuji_sensia_100 | fuji_superia_100 | fuji_superia_100_+ |
          fuji_superia_100_++ | fuji_superia_100_- | fuji_superia_1600 | fuji_superia_1600_+ |
          fuji_superia_1600_++ | fuji_superia_1600_- | fuji_superia_200 | fuji_superia_200_xpro |
          fuji_superia_400 | fuji_superia_400_+ | fuji_superia_400_++ | fuji_superia_400_- |
          fuji_superia_800 | fuji_superia_800_+ | fuji_superia_800_++ | fuji_superia_800_- |
          fuji_superia_hg_1600 | fuji_superia_reala_100 | fuji_superia_x-tra_800 |
          fuji_velvia_100_generic | fuji_velvia_50 | fuji_xtrans_iii_acros | fuji_xtrans_iii_acros+g |
          fuji_xtrans_iii_acros+r | fuji_xtrans_iii_acros+ye | fuji_xtrans_iii_astia |
          fuji_xtrans_iii_classic_chrome | fuji_xtrans_iii_mono | fuji_xtrans_iii_mono+g |
          fuji_xtrans_iii_mono+r | fuji_xtrans_iii_mono+ye | fuji_xtrans_iii_pro_neg_hi |
          fuji_xtrans_iii_pro_neg_std | fuji_xtrans_iii_provia | fuji_xtrans_iii_sepia |
          fuji_xtrans_iii_velvia | fusion_88 | futuristicbleak_1 | futuristicbleak_2 | futuristicbleak_3 |
           futuristicbleak_4 | golden | golden_bright | golden_fade | golden_mono |
          golden_night_softner_43 | golden_sony_37 | golden_vibrant | goldengate |
          goldfx_bright_spring_breeze | goldfx_bright_summer_heat | goldfx_hot_summer_heat |
          goldfx_perfect_sunset_01min | goldfx_perfect_sunset_05min | goldfx_perfect_sunset_10min |
          goldfx_spring_breeze | goldfx_summer_heat | green_15 | green_2025 | green_action |
          green_afternoon | green_blues | green_conflict | green_day_01 | green_day_02 | green_g_09 |
          green_indoor | green_light | green_mono | green_yellow | hackmanite | happyness_133 | harsh_day
          | harsh_sunset | helios | herderite | heulandite | hiddenite | highlights_protection | hilutite
          | hlg_1_1 | hong_kong | horrorblue | howlite | hydracore | hyla_68 | hypersthene | hypnosis |
          ilford_delta_100 | ilford_delta_3200 | ilford_delta_3200_+ | ilford_delta_3200_++ |
          ilford_delta_3200_- | ilford_delta_400 | ilford_fp_4_plus_125 | ilford_hp_5 | ilford_hp_5_+ |
          ilford_hp_5_++ | ilford_hp_5_- | ilford_hp_5_plus_400 | ilford_hps_800 | ilford_pan_f_plus_50 |
          ilford_xp_2 | indoor_blue | industrial_33 | instantc | justpeachy | k_tone_vintage_kodachrome |
          killstreak | kodak_2383_constlclip | kodak_2383_constlmap | kodak_2383_cuspclip |
          kodak_2393_constlclip | kodak_2393_constlmap | kodak_2393_cuspclip | kodak_bw_400_cn |
          kodak_e-100_gx_ektachrome_100 | kodak_ektachrome_100_vs | kodak_ektachrome_100_vs_generic |
          kodak_ektar_100 | kodak_elite_100_xpro | kodak_elite_chrome_200 | kodak_elite_chrome_400 |
          kodak_elite_color_200 | kodak_elite_color_400 | kodak_elite_extracolor_100 | kodak_hie_hs_infra
          | kodak_kodachrome_200 | kodak_kodachrome_25 | kodak_kodachrome_64 |
          kodak_kodachrome_64_generic | kodak_portra_160 | kodak_portra_160_+ | kodak_portra_160_++ |
          kodak_portra_160_- | kodak_portra_160_nc | kodak_portra_160_nc_+ | kodak_portra_160_nc_++ |
          kodak_portra_160_nc_- | kodak_portra_160_vc | kodak_portra_160_vc_+ | kodak_portra_160_vc_++ |
          kodak_portra_160_vc_- | kodak_portra_400 | kodak_portra_400_+ | kodak_portra_400_++ |
          kodak_portra_400_- | kodak_portra_400_nc | kodak_portra_400_nc_+ | kodak_portra_400_nc_++ |
          kodak_portra_400_nc_- | kodak_portra_400_uc | kodak_portra_400_uc_+ | kodak_portra_400_uc_++ |
          kodak_portra_400_uc_- | kodak_portra_400_vc | kodak_portra_400_vc_+ | kodak_portra_400_vc_++ |
          kodak_portra_400_vc_- | kodak_portra_800 | kodak_portra_800_+ | kodak_portra_800_++ |
          kodak_portra_800_- | kodak_portra_800_hc | kodak_t-max_100 | kodak_t-max_3200 | kodak_t-max_400
          | kodak_tmax_3200 | kodak_tmax_3200_+ | kodak_tmax_3200_++ | kodak_tmax_3200_- |
          kodak_tmax_3200_alt | kodak_tri-x_400 | kodak_tri-x_400_+ | kodak_tri-x_400_++ |
          kodak_tri-x_400_- | kodak_tri-x_400_alt | korben_214 | landscape_1 | landscape_10 | landscape_2
          | landscape_3 | landscape_4 | landscape_5 | landscape_6 | landscape_7 | landscape_8 |
          landscape_9 | lateafternoonwanderlust | latesunset | lc_1 | lc_10 | lc_2 | lc_3 | lc_4 | lc_5 |
          lc_6 | lc_7 | lc_8 | lc_9 | lenox_340 | life_giving_tree | light_blown | lomo |
          lomography_redscale_100 | lomography_x-pro_slide_200 | low_contrast_blue | low_key_01 |
          lucky_64 | lushgreensummer | magenta_day | magenta_day_01 | magenta_dream | magentacoffee |
          matrix | mckinnon_75 | memories | milo_5 | minimalistcaffeination | mono_tinted | monochrome_1 |
           monochrome_2 | moody_1 | moody_10 | moody_2 | moody_3 | moody_4 | moody_5 | moody_6 | moody_7 |
           moody_8 | moody_9 | moonlight | moonlight_01 | moonrise | morning_6 | morroco_16 | mostly_blue
          | moviz_1 | moviz_10 | moviz_11 | moviz_12 | moviz_13 | moviz_14 | moviz_15 | moviz_16 |
          moviz_17 | moviz_18 | moviz_19 | moviz_2 | moviz_20 | moviz_21 | moviz_22 | moviz_23 | moviz_24
          | moviz_25 | moviz_26 | moviz_27 | moviz_28 | moviz_29 | moviz_3 | moviz_30 | moviz_31 |
          moviz_32 | moviz_33 | moviz_34 | moviz_35 | moviz_36 | moviz_37 | moviz_38 | moviz_39 | moviz_4
          | moviz_40 | moviz_41 | moviz_42 | moviz_43 | moviz_44 | moviz_45 | moviz_46 | moviz_47 |
          moviz_48 | moviz_5 | moviz_6 | moviz_7 | moviz_8 | moviz_9 | mute_shift | muted_01 | muted_fade
          | mysticpurplesunset | natural_vivid | nemesis | neon_770 | night_01 | night_blade_4 |
          night_king_141 | nightfromday | nostalgiahoney | nostalgic | nw-1 | nw-10 | nw-2 | nw-3 | nw-4 |
           nw-5 | nw-6 | nw-7 | nw-8 | nw-9 | old_west | only_red | only_red_and_blue | operation_yellow |
           orange_dark_4 | orange_dark_7 | orange_dark_look | orange_tone | orange_underexposed | oranges
          | paladin | paladin_1875 | pasadena_21 | pink_fade | pitaya_15 | polaroid_664 | polaroid_665 |
          polaroid_665_+ | polaroid_665_++ | polaroid_665_- | polaroid_665_-- | polaroid_665_negative |
          polaroid_665_negative_+ | polaroid_665_negative_- | polaroid_665_negative_hc | polaroid_667 |
          polaroid_669 | polaroid_669_+ | polaroid_669_++ | polaroid_669_+++ | polaroid_669_- |
          polaroid_669_-- | polaroid_669_cold | polaroid_669_cold_+ | polaroid_669_cold_- |
          polaroid_669_cold_-- | polaroid_672 | polaroid_690 | polaroid_690_+ | polaroid_690_++ |
          polaroid_690_- | polaroid_690_-- | polaroid_690_cold | polaroid_690_cold_+ | polaroid_690_cold_+
          + | polaroid_690_cold_- | polaroid_690_cold_-- | polaroid_690_warm | polaroid_690_warm_+ |
          polaroid_690_warm_++ | polaroid_690_warm_- | polaroid_690_warm_-- | polaroid_polachrome |
          polaroid_px-100uv+_cold | polaroid_px-100uv+_cold_+ | polaroid_px-100uv+_cold_++ |
          polaroid_px-100uv+_cold_+++ | polaroid_px-100uv+_cold_- | polaroid_px-100uv+_cold_-- |
          polaroid_px-100uv+_warm | polaroid_px-100uv+_warm_+ | polaroid_px-100uv+_warm_++ |
          polaroid_px-100uv+_warm_+++ | polaroid_px-100uv+_warm_- | polaroid_px-100uv+_warm_-- |
          polaroid_px-680 | polaroid_px-680_+ | polaroid_px-680_++ | polaroid_px-680_- |
          polaroid_px-680_-- | polaroid_px-680_cold | polaroid_px-680_cold_+ | polaroid_px-680_cold_++ |
          polaroid_px-680_cold_++_alt | polaroid_px-680_cold_- | polaroid_px-680_cold_-- |
          polaroid_px-680_warm | polaroid_px-680_warm_+ | polaroid_px-680_warm_++ |
          polaroid_px-680_warm_- | polaroid_px-680_warm_-- | polaroid_px-70 | polaroid_px-70_+ |
          polaroid_px-70_++ | polaroid_px-70_+++ | polaroid_px-70_- | polaroid_px-70_-- |
          polaroid_px-70_cold | polaroid_px-70_cold_+ | polaroid_px-70_cold_++ | polaroid_px-70_cold_- |
          polaroid_px-70_cold_-- | polaroid_px-70_warm | polaroid_px-70_warm_+ | polaroid_px-70_warm_++ |
          polaroid_px-70_warm_- | polaroid_px-70_warm_-- | polaroid_time_zero_expired |
          polaroid_time_zero_expired_+ | polaroid_time_zero_expired_++ | polaroid_time_zero_expired_- |
          polaroid_time_zero_expired_-- | polaroid_time_zero_expired_--- |
          polaroid_time_zero_expired_cold | polaroid_time_zero_expired_cold_- |
          polaroid_time_zero_expired_cold_-- | polaroid_time_zero_expired_cold_--- | portrait_1 |
          portrait_10 | portrait_2 | portrait_3 | portrait_4 | portrait_5 | portrait_6 | portrait_7 |
          portrait_8 | portrait_9 | protect_highlights_01 | purple | purple_2 | red_afternoon_01 |
          red_day_01 | red_dream_01 | redblueyellow | reds | reds_oranges_yellows | reeve_38 | remy_24 |
          rest_33 | retro | retro_brown_01 | retro_magenta_01 | retro_summer_3 | retro_yellow_01 |
          rollei_ir_400 | rollei_ortho_25 | rollei_retro_100_tonal | rollei_retro_80s | rotate_muted |
          rotate_vibrant | rotated | rotated_crush | saturated_blue | saving_private_damon |
          science_fiction | seringe_4 | serpent | shadow_king_39 | smart_contrast | smokey |
          smooth_cromeish | smooth_fade | soft_fade | softwarming | solarized_color | solarized_color_2 |
          springmorning | sprocket_231 | spy_29 | studio_skin_tone_shaper | subtle_blue | subtle_green |
          subtle_yellow | summer | summer_alt | sunny | sunny_alt | sunny_rich | sunny_warm | super_warm |
           super_warm_rich | sutro_fx | teal_moonlight | tealmagentagold | tealorange | tealorange_1 |
          tealorange_2 | tealorange_3 | technicalfx_backlight_filter | teigen_28 | tensiongreen_1 |
          tensiongreen_2 | tensiongreen_3 | tensiongreen_4 | terra_4 | the_matrices | thriller_2 |
          toastedgarden | trent_18 | true_colors_8 | turkiest_42 | tweed_71 | vibrant | vibrant_alien |
          vibrant_contrast | vibrant_cromeish | victory | vintage | vintage_163 | vintage_alt |
          vintage_brighter | vintage_chrome | vintage_warmth_1 | vireo_37 | warm | warm_highlight |
          warm_yellow | winterlighthouse | wooden_gold_20 | yellow_55b | yellow_film_01 | yellowstone |
          zed_32 | zeke_39 | zilverfx_bw_solarization | zilverfx_infrared | zilverfx_vintage_bw }

        Default values: 'resolution=48' and 'cut_and_round=1'.
    command (+):
        _add_debug_info={ 0 | 1 },{ filename | http[s]://URL | "string" }
        Import G'MIC custom commands from specified file, URL or string.
        (eq. to 'm').
        Imported commands are available directly after the 'command' invocation.

        Default value: 'add_debug_info=1'.
    cursor (+):
        _mode = { 0=hide | 1=show }
        Show or hide mouse cursor for selected instant display windows.
        Command selection (if any) stands for instant display window indices instead of image indices.

        Default value: 'mode=1'.
    display (+):
        _X[%]>=0,_Y[%]>=0,_Z[%]>=0,_exit_on_anykey={ 0 | 1 }
        Display selected images in an interactive viewer (use the instant display window [0] if opened).
        (eq. to 'd').
        Arguments 'X','Y','Z' determine the initial selection view, for 3D volumetric images.

        Default value: 'X=Y=Z=0' and 'exit_on_anykey=0'.
    display0:
        Display selected images without value normalization.
        (eq. to 'd0').
    display2d:
        Display selected 2d images in an interactive window.
        (eq. to 'd2d').
        This command is used by default by command 'display' when displaying 2d images.
        When interactive window is opened, the following actions are possible:
        - Left mouse button: Create an image selection and zoom into it.
        - Middle mouse button, or CTRL+left mouse button: Move image.
        - Mouse wheel or PADD+/-: Zoom in/out.
        - Arrow keys: Move image left/right/up/down.
        - CTRL + A: Enable/disable transparency (show/hide alpha channel).
        - CTRL + C: Decrease window size.
        - CTRL + D: Increase window size.
        - CTRL + F: Toggle fullscreen mode.
        - CTRL + N: Change normalization mode (can be 'none' | 'normal' | 'channel-by-channel').
        - CTRL + O: Save a copy of the input image, as a numbered file 'gmic_xxxxxx.gmz'.
        - CTRL + R: Reset both window size and view.
        - CTRL + S: Save a screenshot of the current view, as a numbered file 'gmic_xxxxxx.png'.
        - CTRL + SPACE: Reset view.
        - CTRL + X: Show/hide axes.
        - CTRL + Z: Hold/release aspect ratio.
    display3d (+):
        _[background_image],_exit_on_anykey={ 0 | 1 } |
        _exit_on_anykey={ 0 | 1 }
        Display selected 3D objects in an interactive viewer (use the instant display window [0] if opened).
        (eq. to 'd3d').

        Default values: '[background_image]=(default)' and 'exit_on_anykey=0'.
    display_array:
        _width>0,_height>0
        Display images in interactive windows where pixel neighborhoods can be explored.

        Default values: 'width=13' and 'height=width'.
    display_fft:
        Display fourier transform of selected images, with centered log-module and argument.
        (eq. to 'dfft').
    display_graph:
        _width>=0,_height>=0,_plot_type,_vertex_type,_xmin,_xmax,_ymin,_ymax,_xlabel,_ylabel
        Render graph plot from selected image data.
        'plot_type' can be { 0=none | 1=lines | 2=splines | 3=bar }.
        'vertex_type' can be { 0=none | 1=points | 2,3=crosses | 4,5=circles | 6,7=squares }.
        'xmin','xmax','ymin','ymax' set the coordinates of the displayed xy-axes.
        if specified 'width' or 'height' is '0', then image size is set to half the screen size.

        Default values: 'width=0', 'height=0', 'plot_type=1', 'vertex_type=1', 'xmin=xmax=ymin=ymax=0
          (auto)', 'xlabel="x-axis"' and 'ylabel="y-axis"'.
    display_histogram:
        _width>=0,_height>=0,_clusters>0,_min_value[%],_max_value[%],_show_axes={ 0 | 1
          },_expression.
        Render a channel-by-channel histogram.
        If selected images have several slices, the rendering is performed for all input slices.
        'expression' is a mathematical expression used to transform the histogram data for
          visualization purpose.
        (eq. to 'dh').
        if specified 'width' or 'height' is '0', then image size is set to half the screen size.

        Default values: 'width=0', 'height=0', 'clusters=256', 'min_value=0%', 'max_value=100%',
          'show_axes=1' and 'expression=i'.
    display_parametric:
        _width>0,_height>0,_outline_opacity,_vertex_radius>=0,_is_antialiased={ 0 | 1 },
          _is_decorated={ 0 | 1 },_xlabel,_ylabel
        Render 2D or 3D parametric curve or point clouds from selected image data.
        Curve points are defined as pixels of a 2 or 3-channel image.
        If the point image contains more than 3 channels, additional channels define the (R,G,B) color
          for each vertex.
        If 'outline_opacity>1', the outline is colored according to the specified vertex colors and
        'outline_opacity-1' is used as the actual drawing opacity.

        Default values: 'width=512', 'height=width', 'outline_opacity=3', 'vertex_radius=0',
          'is_antialiased=1','is_decorated=1', 'xlabel="x-axis"' and 'ylabel="y-axis"'.
    display_parallel:
        Display each selected image in a separate interactive display window.
        (eq. to 'dp').
    display_parallel0:
        Display each selected image in a separate interactive display window, without value
          normalization.
        (eq. to 'dp0').
    display_polar:
        _width>32,_height>32,_outline_type,_fill_R,_fill_G,_fill_B,_theta_start,
          _theta_end,_xlabel,_ylabel
        Render polar curve from selected image data.
        'outline_type' can be { r<0=dots with radius -r | 0=no outline | r>0=lines+dots with radius r }.
        'fill_color' can be { -1=no fill | R,G,B=fill with specified color }.

        Default values: 'width=500', 'height=width', 'outline_type=1', 'fill_R=fill_G=fill_B=200',
          'theta_start=0', 'theta_end=360', 'xlabel="x-axis"' and 'ylabel="y-axis"'.
    display_quiver:
        _size_factor>0,_arrow_size>=0,_color_mode={ 0=monochrome | 1=grayscale | 2=color }
        Render selected images of 2D vectors as a field of 2D arrows.
        (eq. to 'dq').

        Default values: 'size_factor=16', 'arrow_size=1.5' and 'color_mode=1'.
    display_rgba:
        _background_RGB_color
        Render selected RGBA images over a checkerboard or colored background.
        (eq. to 'drgba').

        Default values: 'background_RGB_color=undefined' (checkerboard).
    display_tensors:
        _size_factor>0,_ellipse_size>=0,_color_mode={ 0=monochrome | 1=grayscale |
          2=color },_outline>=0
        Render selected images of tensors as a field of 2D ellipses.
        (eq. to 'dt').

        Default values: 'size_factor=16', 'ellipse_size=1.5', 'color_mode=2' and 'outline=2'.
    display_warp:
        _cell_size>0
        Render selected 2D warping fields.
        (eq. to 'dw').

        Default value: 'cell_size=15'.
    document_gmic:
        _format={ ascii | bash | html | images | latex },_image_path,_write_wrapper={ 0 | 1 }
        Create documentation of .gmic command files (loaded as raw 'uchar' images), in specified format.

        Default values: 'format=ascii', 'image_path=""' and 'write_wrapper=1'.
        Example(s) : raw:filename.gmic,char document_gmic html,img
    echo (+):
        message
        Output specified message on the error output.
        (eq. to 'e').
        Command selection (if any) stands for displayed call stack subset instead of image indices.
    echo_file:
        filename,message
        Output specified message, appending it to specified output file.
        (similar to 'echo' for specified output file stream).
    echo_stdout:
        message
        Output specified message, on the standard output (stdout).
        (similar to 'echo' for output on standard output instead of standard error).
    function1d:
        0<=smoothness<=1,x0>=0,y0,x1>=0,y1,...,xn>=0,yn
        Insert continuous 1D function from specified list of keypoints (xk,yk)
        in range [0,max(xk)] (xk are positive integers).

        Default values: 'smoothness=1' and 'x0=y0=0'.
    input (+):
        [type:]filename |
        [type:]http://URL |
        [selection]x_nb_copies>0 |
        { width>0[%] | [image_w] },{ _height>0[%] | [image_h] },{ _depth>0[%] |
          [image_d] },{ _spectrum>0[%] | [image_s] },_{ value1,_value2,... | 'formula' } |
        (value1{,|;|/|^}value2{,|;|/|^}...) |
        0
        Insert a new image taken from a filename or from a copy of an existing image [index],
        or insert new image with specified dimensions and values. Single quotes may be omitted in
        'formula'. Specifying argument '0' inserts an 'empty' image.
        (eq. to 'i' | (no arg)).

        Default values: 'nb_copies=1', 'height=depth=spectrum=1' and 'value1=0'.
    input_cube:
        "filename",_convert_1d_cluts_to_3d={ 0 | 1 }.
        Insert CLUT data from a .cube filename (Adobe CLUT file format).

        Default value: 'convert_1d_cluts_to_3d=1'.
    input_glob:
        pattern
        Insert new images from several filenames that match the specified glob pattern.
    input_gpl:
        filename
        Input specified filename as a .gpl palette data file.
    output (+):
        [type:]filename,_format_options
        Output selected images as one or several numbered file(s).
        (eq. to 'o').

        Default value: 'format_options'=(undefined).
    output_cube:
        filename
        Output selected CLUTs as a .cube file (Adobe CLUT format).
    output_ggr:
        filename,_gradient_name
        Output selected images as .ggr gradient files (GIMP).
        If no gradient name is specified, it is deduced from the filename.
    outputn:
        filename,_index
        Output selected images as automatically numbered filenames in repeat...done loops.
        (eq. to 'on').
    outputp:
        prefix
        Output selected images as prefixed versions of their original filenames.
        (eq. to 'op').

        Default value: 'prefix=_'.
    outputw:
        Output selected images by overwriting their original location.
        (eq. to 'ow').
    outputx:
        extension1,_extension2,_...,_extensionN,_output_at_same_location={ 0 | 1 }
        Output selected images with same base filenames but for N different extensions.
        (eq. to 'ox').

        Default value: 'output_at_same_location=0'.
    pass (+):
        _shared_state={ 0=non-shared (copy) | 1=shared | 2=adaptive }
        Insert images from parent context of a custom command or a local environment.
        Command selection (if any) stands for a selection of images in the parent context.
        By default (adaptive shared state), selected images are inserted in a shared state if they do
          not belong
        to the context (selection) of the current custom command or local environment as well.
        Typical use of command 'pass' concerns the design of custom commands that take images as
          arguments.

        Default value: 'shared_state=2'.
    plot (+):
        _plot_type,_vertex_type,_xmin,_xmax,_ymin,_ymax,_exit_on_anykey={ 0 | 1 } |
        'formula',_resolution>=0,_plot_type,_vertex_type,_xmin,xmax,_ymin,_ymax,
          _exit_on_anykey={ 0 | 1 }
        Display selected images or formula in an interactive viewer (use the instant display window [0]
          if opened).
        'plot_type' can be { 0=none | 1=lines | 2=splines | 3=bar }.
        'vertex_type' can be { 0=none | 1=points | 2,3=crosses | 4,5=circles | 6,7=squares }.
        'xmin','xmax','ymin','ymax' set the coordinates of the displayed xy-axes.

        Default values: 'plot_type=1', 'vertex_type=1', 'xmin=xmax=ymin=ymax=0 (auto)' and
          'exit_on_anykey=0'.
    print (+):
        Output information on selected images, on the standard error (stderr).
        (eq. to 'p').
    restore (+):
        variable_name1,_variable_name2,...
        Restore images previously stored in the specified named variables, and insert them at the end
        of the image list. Note that restoring image data does not remove the data from
        the corresponding named variable (use 'variable_name=' to explicitely delete a variable content).
    screen (+):
        _x0[%],_y0[%],_x1[%],_y1[%]
        Take screenshot, optionally grabbed with specified coordinates, and insert it
        at the end of the image list.
    select (+):
        feature_type,_X[%]>=0,_Y[%]>=0,_Z[%]>=0,_exit_on_anykey={ 0 | 1 },
          _is_deep_selection={ 0 | 1 }
        Interactively select a feature from selected images (use the instant display window [0] if opened).
        'feature_type' can be { 0=point | 1=segment | 2=rectangle | 3=ellipse }.
        Arguments 'X','Y','Z' determine the initial selection view, for 3D volumetric images.
        The retrieved feature is returned as a 3D vector (if 'feature_type==0') or as a 6d vector
        (if 'feature_type!=0') containing the feature coordinates.

        Default values: 'X=Y=Z=(undefined)', 'exit_on_anykey=0' and 'is_deep_selection=0'.
    serialize (+):
        _datatype,_is_compressed={ 0 | 1 },_store_names={ 0 | 1 }
        Serialize selected list of images into a single image, optionnally in a compressed form.
        'datatype' can be { auto | uchar | char | ushort | short | uint | int | uint64 | int64 | float |
           double }.
        Specify 'datatype' if all selected images have a range of values constrained to a particular datatype,
        in order to minimize the memory footprint.
        The resulting image has only integers values in [0,255] and can then be saved as a raw image of
        unsigned chars (doing so will output a valid .cimg[z] or .gmz file).
        If 'store_names' is set to '1', serialization uses the .gmz format to store data in memory
        (otherwise the .cimg[z] format).

        Default values: 'datatype=auto', 'is_compressed=1' and 'store_names=1'.
    shape_circle:
        _size>=0
        Input a 2D circle binary shape with specified size.

        Default value: 'size=512'.
    shape_cupid:
        _size>=0
        Input a 2D cupid binary shape with specified size.

        Default value: 'size=512'.
    shape_diamond:
        _size>=0
        Input a 2D diamond binary shape with specified size.

        Default value: 'size=512'.
    shape_fern:
        _size>=0,_density[%]>=0,_angle,0<=_opacity<=1,_type={ 0=Asplenium
          adiantum-nigrum | 1=Thelypteridaceae }
        Input a 2D Barnsley fern with specified size.

        Default value: 'size=512', 'density=50%', 'angle=30', 'opacity=0.3' and 'type=0'.
    shape_gear:
        _size>=0,_nb_teeth>0,0<=_height_teeth<=100,0<=_offset_teeth<=100,
          0<=_inner_radius<=100
        Input a 2D gear binary shape with specified size.

        Default value: 'size=512', 'nb_teeth=12', 'height_teeth=20', 'offset_teeth=0' and
          'inner_radius=40'.
    shape_heart:
        _size>=0
        Input a 2D heart binary shape with specified size.

        Default value: 'size=512'.
    shape_polygon:
        _size>=0,_nb_vertices>=3,_angle
        Input a 2D polygonal binary shape with specified geometry.

        Default value: 'size=512', 'nb_vertices=5' and 'angle=0'.
    shape_snowflake:
        size>=0,0<=_nb_recursions<=6
        Input a 2D snowflake binary shape with specified size.

        Default values: 'size=512' and 'nb_recursions=5'.
    shape_star:
        _size>=0,_nb_branches>0,0<=_thickness<=1
        Input a 2D star binary shape with specified size.

        Default values: 'size=512', 'nb_branches=5' and 'thickness=0.38'.
    shared (+):
        x0[%],x1[%],y[%],z[%],v[%] |
        y0[%],y1[%],z[%],v[%] |
        z0[%],z1[%],v[%] |
        v0[%],v1[%] |
        v0[%] |
        (no arg)
        Insert shared buffers from (opt. points/rows/planes/channels of) selected images.
        Shared buffers cannot be returned by a command, nor a local environment.
        (eq. to 'sh').
    sample:
        _name1={ ? | apples | balloons | barbara | boats | bottles | butterfly |
          cameraman | car | cat | cliff | chick | colorful | david | dog | duck | eagle |
          elephant | earth | flower | fruits | gmicky | gmicky_mahvin | gmicky_wilber |
          greece | gummy | house | inside | landscape | leaf | lena | leno | lion |
          mandrill | monalisa | monkey | parrots | pencils | peppers | portrait0 |
          portrait1 | portrait2 | portrait3 | portrait4 | portrait5 | portrait6 |
          portrait7 | portrait8 | portrait9 | roddy | rooster | rose | square | swan |
          teddy | tiger | tulips | wall | waterfall | zelda },_name2,...,_nameN,_width={
          >=0 | 0 (auto) },_height = { >=0 | 0 (auto) } |
        (no arg)
        Input a new sample RGB image (opt. with specified size).
        (eq. to 'sp').
        Argument 'name' can be replaced by an integer which serves as a sample index.
    srand (+):
        value |
        (no arg)
        Set random generator seed.
        If no argument is specified, a random value is used as the random generator seed.
    store (+):
        variable_name1,_variable_name2,...
        Store selected images into one or several named variables.
        Selected images are transferred to the variables, and are so removed from the image list.
        (except if the prepended variant of the command '+store[selection]' is used).
        If a single variable name is specified, all images of the selection are assigned
        to the named variable. Otherwise, there must be as many variable names as images
        in the selection, and each selected image is assigned to each specified named variable.
        Use command 'restore' to get the stored images back in the list.
    string:
        "string"
        Insert new image containing the ascii codes of specified string.
    testimage2d:
        _width>0,_height>0,_spectrum>0
        Input a 2D synthetic image.

        Default values: 'width=512', 'height=width' and 'spectrum=3'.
    uncommand (+):
        command_name[,_command_name2,...] |
        *
        Discard definition of specified custom commands.
        Set argument to '*' for discarding all existing custom commands.
    uniform_distribution:
        nb_levels>=1,spectrum>=1
        Input set of uniformly distributed spectrum-d points in [0,1]^spectrum.
    unserialize (+):
        Recreate lists of images from serialized image buffers, obtained with command 'serialize'.
    update:
        Update commands from the latest definition file on the G'MIC server.
        (eq. to 'up').
    verbose (+):
        level |
        { + | - }
        Set or increment/decrement the verbosity level. Default level is 0.
        (eq. to 'v').
        When 'level'>=0, G'MIC log messages are displayed on the standard error (stderr).

        Default value: 'level=0'.
    wait (+):
        delay |
        (no arg)
        Wait for a given delay (in ms), optionally since the last call to 'wait'.
        or wait for a user event occurring on the selected instant display windows.
        'delay' can be { <0=delay+flush events | 0=event | >0=delay }.
        Command selection (if any) stands for instant display window indices instead of image indices.
        If no window indices are specified and if 'delay' is positive, the command results
        in a 'hard' sleep during specified delay.

        Default value: 'delay=0'.
    warn (+):
        _force_visible={ 0 | 1 },_message
        Print specified warning message, on the standard error (stderr).
        Command selection (if any) stands for displayed call stack subset instead of image indices.
    window (+):
        _width[%]>=-1,_height[%]>=-1,_normalization,_fullscreen,_pos_x[%],_pos_y[%],_title
        Display selected images into an instant display window with specified size, normalization type,
        fullscreen mode and title.
        (eq. to 'w').
        If 'width' or 'height' is set to -1, the corresponding dimension is adjusted to the window
        or image size.
        When arguments 'pos_x' and 'pos_y' are both different than -1, the window is moved to
        the specified coordinates.
        'width'=0 or 'height'=0 closes the instant display window.
        'normalization' can be { -1=keep same | 0=none | 1=always | 2=1st-time | 3=auto }.
        'fullscreen' can be { -1=keep same | 0=no | 1=yes }.
        You can manage up to 10 different instant display windows by using the numbered variants
        'w0' (default, eq. to 'w'),'w1',...,'w9' of the command 'w'.
        Invoke 'window' with no selection to make the window visible, if is has been closed by the user.

        Default values: 'width=height=normalization=fullscreen=-1' and 'title=(undefined)'.
 ** List Manipulation:
    keep (+):
        Keep only selected images.
        (eq. to 'k').
    move (+):
        position[%]
        Move selected images at specified position.
        (eq. to 'mv').
    name (+):
        "name1","name2",...
        Set names of selected images.
        - If the selection contains a single image, then it is assumed the command has a single name
        argument (possibly containing multiple comas).
        - If the selection contains more than one image, each command argument defines a single image
        name for each image of the selection.
        (eq. to 'nm').
    remove (+):
        Remove selected images.
        (eq. to 'rm').
    remove_duplicates:
        Remove duplicates images in the selected images list.
    remove_empty:
        Remove empty images in the selected image list.
    reverse (+):
        Reverse positions of selected images.
        (eq. to 'rv').
    sort_list:
        _ordering={ + | - },_criterion
        Sort list of selected images according to the specified image criterion.

        Default values: 'ordering=+', 'criterion=i'.
    sort_str:
        Sort selected images (viewed as a list of strings) in lexicographic order.
 ** Mathematical Operators:
    abs (+):
        Compute the pointwise absolute values of selected images.
    acos (+):
        Compute the pointwise arccosine of selected images.
    acosh (+):
        Compute the pointwise hyperbolic arccosine of selected images.
    add (+):
        value[%] |
        [image] |
        'formula' |
        (no arg)
        Add specified value, image or mathematical expression to selected images,
        or compute the pointwise sum of selected images.
        (eq. to '+').
    and (+):
        value[%] |
        [image] |
        'formula' |
        (no arg)
        Compute the bitwise AND of selected images with specified value, image or mathematical
        expression, or compute the pointwise sequential bitwise AND of selected images.
        (eq. to '&').
    argmax:
        Compute the argmax of selected images. Returns a single image
        with each pixel value being the index of the input image with maximal value.
    argmin:
        Compute the argmin of selected images. Returns a single image
        with each pixel value being the index of the input image with minimal value.
    asin (+):
        Compute the pointwise arcsine of selected images.
    asinh (+):
        Compute the pointwise hyperbolic arcsine of selected images.
    atan (+):
        Compute the pointwise arctangent of selected images.
    atan2 (+):
        [x_argument]
        Compute the pointwise oriented arctangent of selected images.
        Each selected image is regarded as the y-argument of the arctangent function, while the
        specified image gives the corresponding x-argument.
    atanh (+):
        Compute the pointwise hyperbolic arctangent of selected images.
    bsl (+):
        value[%] |
        [image] |
        'formula' |
        (no arg)
        Compute the bitwise left shift of selected images with specified value, image or
        mathematical expression, or compute the pointwise sequential bitwise left shift of
        selected images.
        (eq. to '<<').
    bsr (+):
        value[%] |
        [image] |
        'formula' |
        (no arg)
        Compute the bitwise right shift of selected images with specified value, image or"
        mathematical expression, or compute the pointwise sequential bitwise right shift of
        selected images.
        (eq. to '>>').
    cos (+):
        Compute the pointwise cosine of selected images.
    cosh (+):
        Compute the pointwise hyperbolic cosine of selected images.
    div (+):
        value[%] |
        [image] |
        'formula' |
        (no arg)
        Divide selected images by specified value, image or mathematical expression,
        or compute the pointwise quotient of selected images.
        (eq. to '/').
    div_complex:
        [divider_real,divider_imag],_epsilon>=0
        Perform division of the selected complex pairs (real1,imag1,...,realN,imagN) of images by
        specified complex pair of images (divider_real,divider_imag).
        In complex pairs, the real image must be always located before the imaginary image in the image list.

        Default value: 'epsilon=1e-8'.
    eq (+):
        value[%] |
        [image] |
        'formula' |
        (no arg)
        Compute the boolean equality of selected images with specified value, image or
        mathematical expression, or compute the boolean equality of selected images.
        (eq. to '==').
    exp (+):
        Compute the pointwise exponential of selected images.
    ge (+):
        value[%] |
        [image] |
        'formula' |
        (no arg)
        Compute the boolean 'greater or equal than' of selected images with specified value, image
        or mathematical expression, or compute the boolean 'greater or equal than' of selected images.
        (eq. to '>=').
    gt (+):
        value[%] |
        [image] |
        'formula' |
        (no arg)
        Compute the boolean 'greater than' of selected images with specified value, image or
        mathematical expression, or compute the boolean 'greater than' of selected images.
        (eq. to '>').
    le (+):
        value[%] |
        [image] |
        'formula' |
        (no arg)
        Compute the boolean 'less or equal than' of selected images with specified value, image or
        mathematical expression, or compute the boolean 'less or equal than' of selected images.
        (eq. to '<=').
    lt (+):
        value[%] |
        [image] |
        'formula' |
        (no arg)
        Compute the boolean 'less than' of selected images with specified value, image or
        mathematical expression, or compute the boolean 'less than' of selected images.
        (eq. to '<').
    log (+):
        Compute the pointwise base-e logarithm of selected images.
    log10 (+):
        Compute the pointwise base-10 logarithm of selected images.
    log2 (+):
        Compute the pointwise base-2 logarithm of selected images
    max (+):
        value[%] |
        [image] |
        'formula' |
        (no arg)
        Compute the maximum between selected images and specified value, image or
        mathematical expression, or compute the pointwise maxima between selected images.
    mdiv (+):
        value[%] |
        [image] |
        'formula' |
        (no arg)
        Compute the matrix division of selected matrices/vectors by specified value, image or
        mathematical expression, or compute the matrix division of selected images.
        (eq. to 'm/').
    min (+):
        value[%] |
        [image] |
        'formula' |
        (no arg)
        Compute the minimum between selected images and specified value, image or
        mathematical expression, or compute the pointwise minima between selected images.
    mod (+):
        value[%] |
        [image] |
        'formula' |
        (no arg)
        Compute the modulo of selected images with specified value, image or mathematical
        expression, or compute the pointwise sequential modulo of selected images.
        (eq. to '%').
    mmul (+):
        value[%] |
        [image] |
        'formula' |
        (no arg)
        Compute the matrix right multiplication of selected matrices/vectors by specified value, image or
        mathematical expression, or compute the matrix right multiplication of selected images.
        (eq. to 'm*').
    mul (+):
        value[%] |
        [image] |
        'formula' |
        (no arg)
        Multiply selected images by specified value, image or mathematical expression,
        or compute the pointwise product of selected images.
        (eq. to '*').
    mul_channels:
        value1,_value2,...,_valueN
        Multiply channels of selected images by specified sequence of values.
    mul_complex:
        [multiplier_real,multiplier_imag]
        Perform multiplication of the selected complex pairs (real1,imag1,...,realN,imagN) of images by
        specified complex pair of images (multiplier_real,multiplier_imag).
        In complex pairs, the real image must be always located before the imaginary image in the image list.
    neq (+):
        value[%] |
        [image] |
        'formula' |
        (no arg)
        Compute the boolean inequality of selected images with specified value, image or
        mathematical expression, or compute the boolean inequality of selected images.
        (eq. to '!=').
    or (+):
        value[%] |
        [image] |
        'formula' |
        (no arg)
        Compute the bitwise OR of selected images with specified value, image or mathematical
        expression, or compute the pointwise sequential bitwise OR of selected images.
        (eq. to '|').
    pow (+):
        value[%] |
        [image] |
        'formula' |
        (no arg)
        Raise selected images to the power of specified value, image or mathematical
        expression, or compute the pointwise sequential powers of selected images.
        (eq. to '^').
    rol (+):
        value[%] |
        [image] |
        'formula' |
        (no arg)
        Compute the bitwise left rotation of selected images with specified value, image or
        mathematical expression, or compute the pointwise sequential bitwise left rotation of
        selected images.
    ror (+):
        value[%] |
        [image] |
        'formula' |
        (no arg)
        Compute the bitwise right rotation of selected images with specified value, image or
        mathematical expression, or compute the pointwise sequential bitwise right rotation of
        selected images.
    sign (+):
        Compute the pointwise sign of selected images.
    sin (+):
        Compute the pointwise sine of selected images.
    sinc (+):
        Compute the pointwise sinc function of selected images.
    sinh (+):
        Compute the pointwise hyperbolic sine of selected images.
    sqr (+):
        Compute the pointwise square function of selected images.
    sqrt (+):
        Compute the pointwise square root of selected images.
    sub (+):
        value[%] |
        [image] |
        'formula' |
        (no arg)
        Subtract specified value, image or mathematical expression to selected images,
        or compute the pointwise difference of selected images.
        (eq. to '-').
    tan (+):
        Compute the pointwise tangent of selected images.
    tanh (+):
        Compute the pointwise hyperbolic tangent of selected images.
    xor (+):
        value[%] |
        [image] |
        'formula' |
        (no arg)
        Compute the bitwise XOR of selected images with specified value, image or mathematical
        expression, or compute the pointwise sequential bitwise XOR of selected images.
 ** Values Manipulation:
    apply_curve:
        0<=smoothness<=1,x0,y0,x1,y1,x2,y2,...,xN,yN
        Apply curve transformation to image values.

        Default values: 'smoothness=1', 'x0=0', 'y0=100'.
    apply_gamma:
        gamma>=0
        Apply gamma correction to selected images.
    balance_gamma:
        _ref_color1,...
        Compute gamma-corrected color balance of selected image, with respect to specified reference color.

        Default value: 'ref_color1=128'.
    cast:
        datatype_source,datatype_target
        Cast datatype of image buffer from specified source type to specified target type.
        'datatype_source' and 'datatype_target' can be { uchar | char | ushort | short | uint | int |
          uint64 | int64 | float | double }.
    complex2polar:
        Compute complex to polar transforms of selected images.
    compress_clut:
        _max_error>0,_avg_error>0,_max_nbpoints>=8
        Compress selected color LUTs as sequences of colored keypoints.

        Default values: 'max_error=8', 'avg_error=2' and 'max_nb_points=2048'.
    compress_rle:
        _is_binary_data={ 0 | 1 },_maximum_sequence_length>=0
        Compress selected images as 2xN data matrices, using RLE algorithm.
        Set 'maximum_sequence_length=0' to disable maximum length constraint.

        Default values: 'is_binary_data=0' and 'maximum_sequence_length=0'.
    cumulate (+):
        { x | y | z | c }...{ x | y | z | c } |
        (no arg)
        Compute the cumulative function of specified image data, optionally along the specified axes.
    cut (+):
        { value0[%] | [image0] },{ value1[%] | [image1] } |
        [image]
        Cut values of selected images in specified range.
        (eq. to 'c').
    decompress_clut_rbf:
        _width>0,_height>0,_depth>0
        Decompress selected colored keypoints into 3D CLUTs, using RBF thin plate spline interpolation.

        Default value: 'width=height=depth=48'.
    decompress_clut_pde:
        _width>0,_height>0,_depth>0
        Decompress selected colored keypoints into 3D CLUTs, using multiscale diffusion PDE's.

        Default values: 'width=height=depth=48'.
    decompress_clut:
        _width>0,_height>0,_depth>0
        Decompress selected colored keypoints into 3D CLUTs, using a mixed RBF/PDE approach.

        Default values: 'width=height=depth=48'.
    decompress_rle:
        Decompress selected data vectors, using RLE algorithm.
    discard (+):
        _value1,_value2,... |
        { x | y | z | c}...{ x | y | z | c},_value1,_value2,... |
        (no arg)
        Discard specified values in selected images or discard neighboring duplicate values,
        optionally only for the values along the first of a specified axis.
        If no values are specified, neighboring duplicate values are discarded.
        If all pixels of a selected image are discarded, an empty image is returned.
    eigen2tensor:
        Recompose selected pairs of eigenvalues/eigenvectors as 2x2 or 3x3 tensor fields.
    endian (+):
        _datatype
        Reverse data endianness of selected images, eventually considering the pixel being of the
          specified datatype.
        'datatype' can be { uchar | char | ushort | short | uint | int | uint64 | int64 | float | double }.
    equalize (+):
        _nb_levels>0[%],_value_min[%],_value_max[%]
        Equalize histograms of selected images.
        If value range is specified, the equalization is done only for pixels in the specified
        value range.

        Default values: 'nb_levels=256', 'value_min=0%' and 'value_max=100%'.
    fill (+):
        value1,_value2,... |
        [image] |
        'formula'
        Fill selected images with values read from the specified value list, existing image
        or mathematical expression. Single quotes may be omitted in 'formula'.
        (eq. to 'f').
    index (+):
        { [palette] | predefined_palette },0<=_dithering<=1,_map_palette={ 0 | 1 }
        Index selected vector-valued images by specified vector-valued palette.
        'predefined_palette' can be { 0=default | 1=HSV | 2=lines | 3=hot | 4=cool | 5=jet | 6=flag | 7=cube }.

        Default values: 'dithering=0' and 'map_palette=0'.
    inrange:
        min[%],max[%]
        Detect pixels whose values are in specified range [min,max], in selected images.
        (eq. to 'ir').
    map (+):
        [palette],_boundary_conditions |
        predefined_palette,_boundary_conditions
        Map specified vector-valued palette to selected indexed scalar images.
        'predefined_palette' can be { 0=default | 1=HSV | 2=lines | 3=hot | 4=cool | 5=jet | 6=flag | 7=cube }.
        'boundary_conditions' can be { 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }.

        Default value: 'boundary_conditions=0'.
    map_clut:
        [clut] | "clut_name"
        Map specified RGB color LUT to selected images.
    mix_channels:
        (a00,...,aMN) |
        [matrix]
        Apply specified matrix to channels of selected images.
    negate:
        base_value |
        (no arg)
        Negate image values.

        Default value: 'base_value=(undefined)'.
    noise (+):
        std_deviation>=0[%],_noise_type
        Add random noise to selected images.
        'noise_type' can be { 0=gaussian | 1=uniform | 2=salt&pepper | 3=poisson | 4=rice }.

        Default value: 'noise_type=0'.
    noise_perlin:
        _scale_x[%]>0,_scale_y[%]>0,_scale_z[%]>0,_seed_x,_seed_y,_seed_z
        Render 2D or 3D Perlin noise on selected images, from specified coordinates.
        The Perlin noise is a specific type of smooth noise,
        described here : 'https://en.wikipedia.org/wiki/Perlin_noise'.

        Default values: 'scale_x=scale_y=scale_z=16' and 'seed_x=seed_y=seed_z=0'.
    noise_poissondisk:
        _radius[%]>0,_max_sample_attempts>0
        Add poisson disk sampling noise to selected images.
        Implements the algorithm from the article "Fast Poisson Disk Sampling in Arbitrary Dimensions",
        by Robert Bridson (SIGGRAPH'2007).

        Default values: 'radius=8' and 'max_sample_attempts=30'.
    normp:
        p>=0
        Compute the pointwise Lp-norm norm of vector-valued pixels in selected images.

        Default value: 'p=2'.
    norm:
        Compute the pointwise euclidean norm of vector-valued pixels in selected images.
    normalize (+):
        { value0[%] | [image0] },{ value1[%] | [image1] } |
        [image]
        Linearly normalize values of selected images in specified range.
        (eq. to 'n').
    normalize_sum:
        Normalize selected images with a unitary sum.
    not:
        Apply boolean not operation on selected images.
    orientation:
        Compute the pointwise orientation of vector-valued pixels in selected images.
    oneminus:
        For each selected image, compute one minus image.
    otsu:
        _nb_levels>0
        Hard-threshold selected images using Otsu's method.
        The computed thresholds are returned as a list of values in the status.

        Default value: 'nb_levels=256'.
    polar2complex:
        Compute polar to complex transforms of selected images.
    quantize:
        nb_levels>=1,_keep_values={ 0 | 1 },_quantization_type={ -1=median-cut |
          0=k-means | 1=uniform }
        Quantize selected images.

        Default value: 'keep_values=1' and 'quantization_type=0'.
    quantize_area:
        _min_area>0
        Quantize selected images such that each flat region has an area greater or equal to 'min_area'.

        Default value: 'min_area=10'.
    rand (+):
        { value0[%] | [image0] },_{ value1[%] | [image1] } |
        [image]
        Fill selected images with random values uniformly distributed in the specified range.
    replace:
        source,target
        Replace pixel values in selected images.
    replace_inf:
        _expression
        Replace all infinite values in selected images by specified expression.
    replace_nan:
        _expression
        Replace all NaN values in selected images by specified expression.
    replace_seq:
        "search_seq","replace_seq"
        Search and replace a sequence of values in selected images.
    replace_str:
        "search_str","replace_str"
        Search and replace a string in selected images (viewed as strings, i.e. sequences of ascii codes).
    round (+):
        rounding_value>=0,_rounding_type |
        (no arg)
        Round values of selected images.
        'rounding_type' can be { -1=backward | 0=nearest | 1=forward }.

        Default value: 'rounding_type=0'.
    roundify:
        gamma>=0
        Apply roundify transformation on float-valued data, with specified gamma.

        Default value: 'gamma=0'.
    set (+):
        value,_x[%],_y[%],_z[%],_c[%]
        Set pixel value in selected images, at specified coordinates.
        (eq. to '=').
        If specified coordinates are outside the image bounds, no action is performed.

        Default values: 'x=y=z=c=0'.
    set_vector_covariance:
        coef1,coef2,...,coefN
        Apply linear transformation on selected images so that the covariance matrix of their
          vector-valued pixels
        is prescribed to given matrix. Matrix size 'N' must be equal to 'spectrum^2'.
    threshold:
        value[%],_is_soft={ 0 | 1 } :
        Threshold values of selected images.
        'soft' can be { 0=hard-thresholding | 1=soft-thresholding }.

        Default value: 'is_soft=0'.
    unrepeat:
        Remove repetition of adjacent values in selected images.
    vector2tensor:
        Convert selected vector fields to corresponding tensor fields.
 ** Colors Manipulation:
    adjust_colors:
        -100<=_brightness<=100,-100<=_contrast<=100,-100<=_gamma<=100,
          -100<=_hue_shift<=100,-100<=_saturation<=100,_value_min,_value_max
        Perform a global adjustment of colors on selected images.
        Range of correct image values are considered to be in [value_min,value_max] (e.g. [0,255]).
        If 'value_min==value_max==0', value range is estimated from min/max values of selected images.
        Processed images have pixel values constrained in [value_min,value_max].

        Default values: 'brightness=0', 'contrast=0', 'gamma=0', 'hue_shift=0', 'saturation=0',
          'value_min=value_max=0'.
    apply_channels:
        "command",color_channels,_value_action={ 0=none | 1=cut | 2=normalize }
        Apply specified command on the chosen color channel(s) of each selected images.
        (eq. to 'ac').
        Argument 'color_channels' refers to a colorspace, and can be basically one of
        { all | rgba | rgb | ryb | lrgb | ycbcr | lab | lch | hsv | hsi | hsl | cmy | cmyk | yiq }.
        You can also make the processing focus on a few particular channels of this colorspace,
        by setting 'color_channels' as 'colorspace_channel' (e.g. 'hsv_h' for the hue).
        All channel values are considered to be provided in the [0,255] range.

        Default value: 'value_action=0'.
    autoindex:
        nb_colors>0,0<=_dithering<=1,_method={ 0=median-cut | 1=k-means }
        Index selected vector-valued images by adapted colormaps.

        Default values: 'dithering=0' and 'method=1'.
    bayer2rgb:
        _GM_smoothness,_RB_smoothness1,_RB_smoothness2
        Transform selected RGB-Bayer sampled images to color images.

        Default values: 'GM_smoothness=RB_smoothness=1' and 'RB_smoothness2=0.5'.
    cmy2rgb:
        Convert color representation of selected images from CMY to RGB.
    cmyk2rgb:
        Convert color representation of selected images from CMYK to RGB.
    colorblind:
        type={ 0=protanopia | 1=protanomaly | 2=deuteranopia | 3=deuteranomaly |
          4=tritanopia | 5=tritanomaly | 6=achromatopsia | 7=achromatomaly }
        Simulate color blindness vision.
    colormap:
        nb_levels>=0,_method={ 0=median-cut | 1=k-means },_sort_vectors={ 0 | 1 }
        Estimate best-fitting colormap with 'nb_colors' entries, to index selected images.
        Set 'nb_levels==0' to extract all existing colors of an image.

        Default value: 'method=1' and 'sort_vectors=1'.
    compose_channels:
        Compose all channels of each selected image, using specified arithmetic operator (+,-,or,min,...).

        Default value: '1=+'.
    direction2rgb:
        Compute RGB representation of selected 2D direction fields.
    ditheredbw:
        Create dithered B&W version of selected images.
    fill_color:
        col1,...,colN
        Fill selected images with specified color.
        (eq. to 'fc').
    gradient2rgb:
        _is_orientation={ 0 | 1 }
        Compute RGB representation of 2D gradient of selected images.

        Default value: 'is_orientation=0'.
    hcy2rgb ::
        Convert color representation of selected images from HCY to RGB.
    hsi2rgb:
        Convert color representation of selected images from HSI to RGB.
    hsi82rgb:
        Convert color representation of selected images from HSI8 to RGB.
    hsl2rgb:
        Convert color representation of selected images from HSL to RGB.
    hsl82rgb:
        Convert color representation of selected images from HSL8 to RGB.
    hsv2rgb:
        Convert color representation of selected images from HSV to RGB.
    hsv82rgb:
        Convert color representation of selected images from HSV8 to RGB.
    int2rgb:
        Convert color representation of selected images from INT24 to RGB.
    lab2lch:
        Convert color representation of selected images from Lab to Lch.
    lab2rgb:
        illuminant={ 0=D50 | 1=D65 } |
        (no arg)
        Convert color representation of selected images from Lab to RGB.

        Default value: 'illuminant=1'.
    lab2srgb:
        illuminant={ 0=D50 | 1=D65 } |
        (no arg)
        Convert color representation of selected images from Lab to sRGB.

        Default value: 'illuminant=1'.
    lab82srgb:
        illuminant={ 0=D50 | 1=D65 } |
        (no arg)
        Convert color representation of selected images from Lab8 to sRGB.

        Default value: 'illuminant=1'.
    lab2xyz:
        illuminant={ 0=D50 | 1=D65 } |
        (no arg)
        Convert color representation of selected images from Lab to XYZ.

        Default value: 'illuminant=1'.
    lab82rgb:
        illuminant={ 0=D50 | 1=D65 } |
        (no arg)
        Convert color representation of selected images from Lab8 to RGB.

        Default value: 'illuminant=1'.
    lch2lab:
        Convert color representation of selected images from Lch to Lab.
    lch2rgb:
        illuminant={ 0=D50 | 1=D65 } |
        (no arg)
        Convert color representation of selected images from Lch to RGB.

        Default value: 'illuminant=1'.
    lch82rgb:
        illuminant={ 0=D50 | 1=D65 } |
        (no arg)
        Convert color representation of selected images from Lch8 to RGB.

        Default value: 'illuminant=1'.
    luminance:
        Compute luminance of selected sRGB images.
    lightness:
        Compute lightness of selected sRGB images.
    lut_rainbow:
        Input a 256-entries RGB colormap of rainbow colors.
    lut_contrast:
        _nb_colors>1,_min_rgb_value
        Generate a RGB colormap where consecutive colors have high contrast.
        This function performs a specific score maximization to generate the result, so
        it may take some time when 'nb_colors' is high.

        Default values: 'nb_colors=256' and 'min_rgb_value=64'.
    mix_rgb:
        a11,a12,a13,a21,a22,a23,a31,a32,a33
        Apply 3x3 specified matrix to RGB colors of selected images.

        Default values: 'a11=1', 'a12=a13=a21=0', 'a22=1', 'a23=a31=a32=0' and 'a33=1'.
    pseudogray:
        _max_increment>=0,_JND_threshold>=0,_bits_depth>0
        Generate pseudogray colormap with specified increment and perceptual threshold.
        If 'JND_threshold' is 0, no perceptual constraints are applied.

        Default values: 'max_increment=5', 'JND_threshold=2.3' and 'bits_depth=8'.
    replace_color:
        tolerance[%]>=0,smoothness[%]>=0,src1,src2,...,dest1,dest2,...
        Replace pixels from/to specified colors in selected images.
    retinex:
        _value_offset>0,_colorspace={ hsi | hsv | lab | lrgb | rgb | ycbcr },
          0<=_min_cut<=100,0<=_max_cut<=100,_sigma_low>0,_sigma_mid>0,_sigma_high>0
        Apply multi-scale retinex algorithm on selected images to improve color consistency.
        (as described in the page http://www.ipol.im/pub/art/2014/107/).

        Default values: 'offset=1', 'colorspace=hsv', 'min_cut=1', 'max_cut=1', 'sigma_low=15',
          'sigma_mid=80' and 'sigma_high=250'.
    rgb2bayer:
        _start_pattern=0,_color_grid=0
        Transform selected color images to RGB-Bayer sampled images.

        Default values: 'start_pattern=0' and 'color_grid=0'.
    rgb2cmy:
        Convert color representation of selected images from RGB to CMY.
    rgb2cmyk:
        Convert color representation of selected images from RGB to CMYK.
    rgb2hcy:
        Convert color representation of selected images from RGB to HCY.
    rgb2hsi:
        Convert color representation of selected images from RGB to HSI.
    rgb2hsi8:
        Convert color representation of selected images from RGB to HSI8.
    rgb2hsl:
        Convert color representation of selected images from RGB to HSL.
    rgb2hsl8:
        Convert color representation of selected images from RGB to HSL8.
    rgb2hsv:
        Convert color representation of selected images from RGB to HSV.
    rgb2hsv8:
        Convert color representation of selected images from RGB to HSV8.
    rgb2int:
        Convert color representation of selected images from RGB to INT24 scalars.
    rgb2lab:
        illuminant={ 0=D50 | 1=D65 } |
        (no arg)
        Convert color representation of selected images from RGB to Lab.

        Default value: 'illuminant=1'.
    rgb2lab8:
        illuminant={ 0=D50 | 1=D65 } |
        (no arg)
        Convert color representation of selected images from RGB to Lab8.

        Default value: 'illuminant=1'.
    rgb2lch:
        illuminant={ 0=D50 | 1=D65 } |
        (no arg)
        Convert color representation of selected images from RGB to Lch.

        Default value: 'illuminant=1'.
    rgb2lch8:
        illuminant={ 0=D50 | 1=D65 } |
        (no arg)
        Convert color representation of selected images from RGB to Lch8.

        Default value: 'illuminant=1'.
    rgb2luv:
        Convert color representation of selected images from RGB to LUV.
    rgb2ryb:
        Convert color representation of selected images from RGB to RYB.
    rgb2srgb:
        Convert color representation of selected images from linear RGB to sRGB.
    rgb2xyz:
        illuminant={ 0=D50 | 1=D65 } |
        (no arg)
        Convert color representation of selected images from RGB to XYZ.

        Default value: 'illuminant=1'.
    rgb2xyz8:
        illuminant={ 0=D50 | 1=D65 } |
        (no arg)
        Convert color representation of selected images from RGB to XYZ8.

        Default value: 'illuminant=1'.
    rgb2yiq:
        Convert color representation of selected images from RGB to YIQ.
    rgb2yiq8:
        Convert color representation of selected images from RGB to YIQ8.
    rgb2ycbcr:
        Convert color representation of selected images from RGB to YCbCr.
    rgb2yuv:
        Convert color representation of selected images from RGB to YUV.
    rgb2yuv8:
        Convert color representation of selected images from RGB to YUV8.
    remove_opacity:
        Remove opacity channel of selected images.
    ryb2rgb:
        Convert color representation of selected images from RYB to RGB.
    select_color:
        tolerance[%]>=0,col1,...,colN
        Select pixels with specified color in selected images.
    sepia:
        Apply sepia tones effect on selected images.
    solarize:
        Solarize selected images.
    split_colors:
        _tolerance>=0,_max_nb_outputs>0,_min_area>0
        Split selected images as several image containing a single color.
        One selected image can be split as at most 'max_nb_outputs' images.
        Output images are sorted by decreasing area of extracted color regions and have an additional
          alpha-channel.

        Default values: 'tolerance=0', 'max_nb_outputs=256' and 'min_area=8'.
    split_opacity:
        Split color and opacity parts of selected images.
    srgb2lab:
        illuminant={ 0=D50 | 1=D65 } |
        (no arg)
        Convert color representation of selected images from sRGB to Lab.

        Default value: 'illuminant=1'.
    srgb2lab8:
        illuminant={ 0=D50 | 1=D65 } |
        (no arg)
        Convert color representation of selected images from sRGB to Lab8.

        Default value: 'illuminant=1'.
    srgb2rgb:
        Convert color representation of selected images from sRGB to linear RGB.
    to_a:
        Force selected images to have an alpha channel.
    to_color:
        Force selected images to be in color mode (RGB or RGBA).
    to_colormode:
        mode={ 0=adaptive | 1=G | 2=GA | 3=RGB | 4=RGBA }
        Force selected images to be in a given color mode.

        Default value: 'mode=0'.
    to_gray:
        Force selected images to be in GRAY mode.
    to_graya:
        Force selected images to be in GRAYA mode.
    to_pseudogray:
        _max_step>=0,_is_perceptual_constraint={ 0 | 1 },_bits_depth>0
        Convert selected scalar images ([0-255]-valued) to pseudo-gray color images.

        Default values: 'max_step=5', 'is_perceptual_constraint=1' and 'bits_depth=8'.
        The original pseudo-gray technique has been introduced by Rich Franzen [http://r0k.us/graphics/
          pseudoGrey.html].
        Extension of this technique to arbitrary increments for more tones, has been done by David
          Tschumperle.
    to_rgb:
        Force selected images to be in RGB mode.
    to_rgba:
        Force selected images to be in RGBA mode.
    transfer_histogram:
        [reference_image],_nb_levels>0,_color_channels
        Transfer histogram of the specified reference image to selected images.
        Argument 'color channels' is the same as with command 'apply_channels'.

        Default value: 'nb_levels=256' and 'color_channels=all'.
    transfer_rgb:
        [target],_gamma>=0,_regularization>=0,_luminosity_constraints>=0,
          _rgb_resolution>=0,_is_constraints={ 0 | 1 }
        Transfer colors from selected source images to selected reference image (given as argument).
        'gamma' determines the importance of color occurrences in the matching process (0=none to 1=huge).
        'regularization' determines the number of guided filter iterations to remove quantization effects.
        'luminosity_constraints' tells if luminosity constraints must be applied on non-confident
          matched colors.
        'is_constraints' tells if additional hard color constraints must be set (opens an interactive window).

        Default values: 'gamma=0.3','regularization=8', 'luminosity_constraints=0.1',
          'rgb_resolution=64' and 'is_constraints=0'.
    xyz2lab:
        illuminant={ 0=D50 | 1=D65 } |
        (no arg)
        Convert color representation of selected images from XYZ to Lab.

        Default value: 'illuminant=1'.
    xyz2rgb:
        illuminant={ 0=D50 | 1=D65 } |
        (no arg)
        Convert color representation of selected images from XYZ to RGB.

        Default value: 'illuminant=1'.
    xyz82rgb:
        illuminant={ 0=D50 | 1=D65 } |
        (no arg)
        Convert color representation of selected images from XYZ8 to RGB.

        Default value: 'illuminant=1'.
    ycbcr2rgb:
        Convert color representation of selected images from YCbCr to RGB.
    yiq2rgb:
        Convert color representation of selected images from YIQ to RGB.
    yiq82rgb:
        Convert color representation of selected images from YIQ8 to RGB.
    yuv2rgb:
        Convert color representation of selected images from YUV to RGB.
    yuv82rgb:
        Convert selected images from YUV8 to RGB color bases.
 ** Geometry Manipulation:
    append (+):
        [image],axis,_centering |
        axis,_centering
        Append specified image to selected images, or all selected images together, along specified axis.
        (eq. to 'a').
        'axis' can be { x | y | z | c }.
        Usual 'centering' values are { 0=left-justified | 0.5=centered | 1=right-justified }.

        Default value: 'centering=0'.
    append_tiles:
        _M>=0,_N>=0,0<=_centering_x<=1,0<=_centering_y<=1
        Append MxN selected tiles as new images.
        If 'N' is set to 0, number of rows is estimated automatically.
        If 'M' is set to 0, number of columns is estimated automatically.
        If 'M' and 'N' are both set to '0', auto-mode is used.
        If 'M' or 'N' is set to 0, only a single image is produced.
        'centering_x' and 'centering_y' tells about the centering of tiles when they have different sizes.

        Default values: 'M=0', 'N=0', 'centering_x=centering_y=0.5'.
    apply_scales:
        "command",number_of_scales>0,_min_scale[%]>=0,_max_scale[%]>=0,_scale_gamma>0,
          _interpolation
        Apply specified command on different scales of selected images.
        'interpolation' can be { 0=none | 1=nearest | 2=average | 3=linear | 4=grid | 5=bicubic |
          6=lanczos }.

        Default value: 'min_scale=25%', 'max_scale=100%' and 'interpolation=3'.
    autocrop (+):
        value1,value2,... |
        (no arg)
        Autocrop selected images by specified vector-valued intensity.
        If no arguments are provided, cropping value is guessed.
    autocrop_components:
        _threshold[%],_min_area[%]>=0,_is_high_connectivity={ 0 | 1 },_output_type={
          0=crop | 1=segmentation | 2=coordinates }
        Autocrop and extract connected components in selected images, according to a mask given as the
          last channel of
        each of the selected image (e.g. alpha-channel).

        Default values: 'threshold=0%', 'min_area=0.1%', 'is_high_connectivity=0' and 'output_type=1'.
    autocrop_seq:
        value1,value2,... | auto
        Autocrop selected images using the crop geometry of the last one by specified vector-valued
          intensity,
        or by automatic guessing the cropping value.

        Default value: auto mode.
    channels (+):
        { [image0] | c0[%] },_{ [image1] | c1[%] }
        Keep only specified channels of selected images.
        Dirichlet boundary is used when specified channels are out of range.
    columns (+):
        { [image0] | x0[%] },_{ [image1] | x1[%] }
        Keep only specified columns of selected images.
        Dirichlet boundary is used when specified columns are out of range.
    crop (+):
        x0[%],x1[%],_boundary_conditions |
        x0[%],y0[%],x1[%],y1[%],_boundary_conditions |
        x0[%],y0[%],z0[%],x1[%],y1[%],z1[%],_boundary_conditions |
        x0[%],y0[%],z0[%],c0[%],x1[%],y1[%],z1[%],c1[%],_boundary_conditions
        Crop selected images with specified region coordinates.
        (eq. to 'z').
        'boundary_conditions' can be { 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }.

        Default value: 'boundary_conditions=0'.
    diagonal:
        Transform selected vectors as diagonal matrices.
    elevate:
        _depth,_is_plain={ 0 | 1 },_is_colored={ 0 | 1 }
        Elevate selected 2D images into 3D volumes.

        Default values: 'depth=64', 'is_plain=1' and 'is_colored=1'.
    expand_x:
        size_x>=0,_boundary_conditions={ 0=dirichlet | 1=neumann | 2=periodic |
          3=mirror }
        Expand selected images along the x-axis.

        Default value: 'boundary_conditions=1'.
    expand_xy:
        size>=0,_boundary_conditions={ 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }
        Expand selected images along the xy-axes.

        Default value: 'boundary_conditions=1'.
    expand_xyz:
        size>=0,_boundary_conditions={ 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }
        Expand selected images along the xyz-axes.

        Default value: 'boundary_conditions=1'.
    expand_y:
        size_y>=0,_boundary_conditions={ 0=dirichlet | 1=neumann | 2=periodic |
          3=mirror }
        Expand selected images along the y-axis.

        Default value: 'boundary_conditions=1'.
    expand_z:
        size_z>=0,_boundary_conditions={ 0=dirichlet | 1=neumann | 2=periodic |
          3=mirror }
        Expand selected images along the z-axis.

        Default value: 'boundary_conditions=1'.
    extract_region:
        [label_image],_extract_xyz_coordinates={ 0 | 1 },_label_1,...,_label_M
        Extract all pixels of selected images whose corresponding label in '[label_image]' is equal to
          'label_m',
        and output them as M column images.

        Default value: 'extract_xyz_coordinates=0'.
    montage:
        "_layout_code",_montage_mode={ 0<=centering<=1 | 2<=scale+2<=3 },_output_mode={
          0=single layer | 1=multiple layers },"_processing_command"
        Create a single image montage from selected images, according to specified layout code :
        - 'X' to assemble all images using an automatically estimated layout.
        - 'H' to assemble all images horizontally.
        - 'V' to assemble all images vertically.
        - 'A' to assemble all images as an horizontal array.
        - 'B' to assemble all images as a vertical array.
        - 'Ha:b' to assemble two blocks 'a' and 'b' horizontally.
        - 'Va:b' to assemble two blocks 'a' and 'b' vertically.
        - 'Ra' to rotate a block 'a' by 90 deg. ('RRa' for 180 deg. and 'RRRa' for 270 deg.).
        - 'Ma' to mirror a block 'a' along the X-axis ('MRRa' for the Y-axis).
        A block 'a' can be an image index (treated periodically) or a nested layout expression 'Hb:c',
          'Vb:c','Rb' or
        'Mb' itself.
        For example, layout code 'H0:V1:2' creates an image where image [0] is on the left, and images
          [1] and [2]
        vertically packed on the right.

        Default values: 'layout_code=X', 'montage_mode=2', output_mode='0' and 'processing_command=""'.
    mirror (+):
        { x | y | z }...{ x | y | z }
        Mirror selected images along specified axes.
    permute (+):
        permutation_string
        Permute selected image axes by specified permutation.
        'permutation' is a combination of the character set {x|y|z|c},
        e.g. 'xycz', 'cxyz', ...
    resize (+):
        [image],_interpolation,_boundary_conditions,_ax,_ay,_az,_ac |
        {[image_w] | width>0[%]},_{[image_h] | height>0[%]},_{[image_d] | depth>0[%]},
          _{[image_s] | spectrum>0[%]},_interpolation,_boundary_conditions,_ax,_ay,_az,_ac
        Resize selected images with specified geometry.
        (eq. to 'r').
        'interpolation' can be { -1=none (memory content) | 0=none | 1=nearest | 2=average | 3=linear |
          4=grid | 5=bicubic | 6=lanczos }.
        'boundary_conditions' has different meanings, according to the chosen 'interpolation' mode :
        . When 'interpolation=={ -1 | 1 | 2 | 4 }', 'boundary_conditions' is meaningless.
        . When 'interpolation==0', 'boundary_conditions' can be { 0=dirichlet | 1=neumann | 2=periodic |
           3=mirror }.
        . When 'interpolation=={ 3 | 5 | 6 }', 'boundary_conditions' can be { 0=none | 1=neumann }.
        'ax,ay,az,ac' set the centering along each axis when 'interpolation=0 or 4'
        (set to '0' by default, must be defined in range [0,1]).

        Default values: 'interpolation=1', 'boundary_conditions=0' and 'ax=ay=az=ac=0'.
    resize_mn:
        width[%]>=0,_height[%]>=0,_depth[%]>=0,_B_value,_C_value
        Resize selected images with Mitchell-Netravali filter (cubic).
        For details about the method, see: https://de.wikipedia.org/wiki/Mitchell-Netravali-Filter

        Default values: 'height=100%', 'depth=100%', 'B=0.3333' and 'C=0.3333'.
    resize_pow2:
        _interpolation,_boundary_conditions,_ax,_ay,_az,_ac
        Resize selected images so that each dimension is a power of 2.
        'interpolation' can be { -1=none (memory content) | 0=none | 1=nearest | 2=average | 3=linear |
          4=grid | 5=bicubic | 6=lanczos }.
        'boundary_conditions' has different meanings, according to the chosen 'interpolation' mode :
        . When 'interpolation=={ -1 | 1 | 2 | 4 }', 'boundary_conditions' is meaningless.
        . When 'interpolation==0', 'boundary_conditions' can be { 0=dirichlet | 1=neumann | 2=periodic |
           3=mirror }.
        . When 'interpolation=={ 3 | 5 | 6 }', 'boundary_conditions' can be { 0=none | 1=neumann }.
        'ax,ay,az,ac' set the centering along each axis when 'interpolation=0'
        (set to '0' by default, must be defined in range [0,1]).

        Default values: 'interpolation=0', 'boundary_conditions=0' and 'ax=ay=az=ac=0'.
    resize_ratio2d:
        width>0,height>0,_mode={ 0=inside | 1=outside | 2=padded },0=<_interpolation<=6
        Resize selected images while preserving their aspect ratio.
        (eq. to 'rr2d').

        Default values: 'mode=0' and 'interpolation=6'.
    resize2dx:
        width[%]>0,_interpolation,_boundary_conditions,_ax,_ay,_az,_ac
        Resize selected images along the x-axis, preserving 2D ratio.
        (eq. to 'r2dx').
        'interpolation' can be { -1=none (memory content) | 0=none | 1=nearest | 2=average | 3=linear |
          4=grid | 5=bicubic | 6=lanczos }.
        'boundary_conditions' has different meanings, according to the chosen 'interpolation' mode :
        . When 'interpolation=={ -1 | 1 | 2 | 4 }', 'boundary_conditions' is meaningless.
        . When 'interpolation==0', 'boundary_conditions' can be { 0=dirichlet | 1=neumann | 2=periodic |
           3=mirror }.
        . When 'interpolation=={ 3 | 5 | 6 }', 'boundary_conditions' can be { 0=none | 1=neumann }.
        'ax,ay,az,ac' set the centering along each axis when 'interpolation=0'
        (set to '0' by default, must be defined in range [0,1]).

        Default values: 'interpolation=3', 'boundary_conditions=0' and 'ax=ay=az=ac=0'.
    resize2dy:
        height[%]>=0,_interpolation,_boundary_conditions,_ax,_ay,_az,_ac
        Resize selected images along the y-axis, preserving 2D ratio.
        (eq. to 'r2dy').
        'interpolation' can be { -1=none (memory content) | 0=none | 1=nearest | 2=average | 3=linear |
          4=grid | 5=bicubic | 6=lanczos }.
        'boundary_conditions' has different meanings, according to the chosen 'interpolation' mode :
        . When 'interpolation=={ -1 | 1 | 2 | 4 }', 'boundary_conditions' is meaningless.
        . When 'interpolation==0', 'boundary_conditions' can be { 0=dirichlet | 1=neumann | 2=periodic |
           3=mirror }.
        . When 'interpolation=={ 3 | 5 | 6 }', 'boundary_conditions' can be { 0=none | 1=neumann }.
        'ax,ay,az,ac' set the centering along each axis when 'interpolation=0'
        (set to '0' by default, must be defined in range [0,1]).

        Default values: 'interpolation=3', 'boundary_conditions=0' and 'ax=ay=az=ac=0'.
    resize3dx:
        width[%]>0,_interpolation,_boundary_conditions,_ax,_ay,_az,_ac
        Resize selected images along the x-axis, preserving 3D ratio.
        (eq. to 'r3dx').
        'interpolation' can be { -1=none (memory content) | 0=none | 1=nearest | 2=average | 3=linear |
          4=grid | 5=bicubic | 6=lanczos }.
        'boundary_conditions' has different meanings, according to the chosen 'interpolation' mode :
        . When 'interpolation=={ -1 | 1 | 2 | 4 }', 'boundary_conditions' is meaningless.
        . When 'interpolation==0', 'boundary_conditions' can be { 0=dirichlet | 1=neumann | 2=periodic |
           3=mirror }.
        . When 'interpolation=={ 3 | 5 | 6 }', 'boundary_conditions' can be { 0=none | 1=neumann }.
        'ax,ay,az,ac' set the centering along each axis when 'interpolation=0'
        (set to '0' by default, must be defined in range [0,1]).

        Default values: 'interpolation=3', 'boundary_conditions=0' and 'ax=ay=az=ac=0'.
    resize3dy:
        height[%]>0,_interpolation,_boundary_conditions,_ax,_ay,_az,_ac
        Resize selected images along the y-axis, preserving 3D ratio.
        (eq. to 'r3dy').
        'interpolation' can be { -1=none (memory content) | 0=none | 1=nearest | 2=average | 3=linear |
          4=grid | 5=bicubic | 6=lanczos }.
        'boundary_conditions' has different meanings, according to the chosen 'interpolation' mode :
        . When 'interpolation=={ -1 | 1 | 2 | 4 }', 'boundary_conditions' is meaningless.
        . When 'interpolation==0', 'boundary_conditions' can be { 0=dirichlet | 1=neumann | 2=periodic |
           3=mirror }.
        . When 'interpolation=={ 3 | 5 | 6 }', 'boundary_conditions' can be { 0=none | 1=neumann }.
        'ax,ay,az,ac' set the centering along each axis when 'interpolation=0'
        (set to '0' by default, must be defined in range [0,1]).

        Default values: 'interpolation=3', 'boundary_conditions=0' and 'ax=ay=az=ac=0'.
    resize3dz:
        depth[%]>0,_interpolation,_boundary_conditions,_ax,_ay,_az,_ac
        Resize selected images along the z-axis, preserving 3D ratio.
        (eq. to 'r3dz').
        'interpolation' can be { -1=none (memory content) | 0=none | 1=nearest | 2=average | 3=linear |
          4=grid | 5=bicubic | 6=lanczos }.
        'boundary_conditions' has different meanings, according to the chosen 'interpolation' mode :
        . When 'interpolation=={ -1 | 1 | 2 | 4 }', 'boundary_conditions' is meaningless.
        . When 'interpolation==0', 'boundary_conditions' can be { 0=dirichlet | 1=neumann | 2=periodic |
           3=mirror }.
        . When 'interpolation=={ 3 | 5 | 6 }', 'boundary_conditions' can be { 0=none | 1=neumann }.
        'ax,ay,az,ac' set the centering along each axis when 'interpolation=0'
        (set to '0' by default, must be defined in range [0,1]).

        Default values: 'interpolation=3', 'boundary_conditions=0' and 'ax=ay=az=ac=0'.
    rotate (+):
        angle,_interpolation,_boundary_conditions,_center_x[%],_center_y[%] |
        u,v,w,angle,interpolation,boundary_conditions,_center_x[%],_center_y[%],
          _center_z[%]
        Rotate selected images with specified angle (in deg.), and optionally 3D axis (u,v,w).
        'interpolation' can be { 0=none | 1=linear | 2=bicubic }.
        'boundary_conditions' can be { 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }.
        When a rotation center (cx,cy,_cz) is specified, the size of the image is preserved.

        Default values: 'interpolation=1', 'boundary_conditions=0' and 'center_x=center_y=(undefined)'.
    rotate_tileable:
        angle,_max_size_factor>=0
        Rotate selected images by specified angle and make them tileable.
        If resulting size of an image is too big, the image is replaced by a 1x1 image.

        Default values: 'max_size_factor=8'.
    rows (+):
        { [image0] | y0[%] },_{ [image1] | y1[%] }
        Keep only specified rows of selected images.
        Dirichlet boundary conditions are used when specified rows are out of range.
    scale2x:
        Resize selected images using the Scale2x algorithm.
    scale3x:
        Resize selected images using the Scale3x algorithm.
    scale_dcci2x:
        _edge_threshold>=0,_exponent>0,_extend_1px={ 0=false | 1=true }
        Double image size using directional cubic convolution interpolation,
        as described in https://en.wikipedia.org/wiki/Directional_Cubic_Convolution_Interpolation.

        Default values: 'edge_threshold=1.15', 'exponent=5' and 'extend_1px=0'.
    seamcarve:
        _width[%]>=0,_height[%]>=0,_is_priority_channel={ 0 | 1 },_is_antialiasing={ 0 |
           1 },_maximum_seams[%]>=0
        Resize selected images with specified 2D geometry, using the seam-carving algorithm.

        Default values: 'height=100%', 'is_priority_channel=0', 'is_antialiasing=1' and
          'maximum_seams=25%'.
    shift (+):
        vx[%],_vy[%],_vz[%],_vc[%],_boundary_conditions,_interpolation={
          0=nearest_neighbor | 1=linear }
        Shift selected images by specified displacement vector.
        Displacement vector can be non-integer in which case linear interpolation should be chosen.
        'boundary_conditions' can be { 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }.

        Default value: 'boundary_conditions=0' and 'interpolation=0'.
    shrink_x:
        size_x>=0
        Shrink selected images along the x-axis.
    shrink_xy:
        size>=0
        Shrink selected images along the xy-axes.
    shrink_xyz:
        size>=0
        Shrink selected images along the xyz-axes.
    shrink_y:
        size_y>=0
        Shrink selected images along the y-axis.
    shrink_z:
        size_z>=0
        Shrink selected images along the z-axis.
    slices (+):
        { [image0] | z0[%] },_{ [image1] | z1[%] }
        Keep only specified slices of selected images.
        Dirichlet boundary conditions are used when specified slices are out of range.
    sort (+):
        _ordering={ + | - },_axis={ x | y | z | c }
        Sort pixel values of selected images.
        If 'axis' is specified, the sorting is done according to the data of the first column/row/slice/channel
        of selected images.

        Default values: 'ordering=+' and 'axis=(undefined)'.
    split (+):
        { x | y | z | c }...{ x | y | z | c },_split_mode |
        keep_splitting_values={ + | - },_{ x | y | z | c }...{ x | y | z | c },value1,
          _value2,... |
        (no arg)
        Split selected images along specified axes, or regarding to a sequence of scalar values
        (optionally along specified axes too).
        (eq. to 's').
        'split_mode' can be { 0=split according to constant values | >0=split in N parts | <0=split in
          parts of size -N }.

        Default value: 'split_mode=-1'.
    split_tiles:
        M!=0,_N!=0,_is_homogeneous={ 0 | 1 }
        Split selected images as a MxN array of tiles.
        If M or N is negative, it stands for the tile size instead.

        Default values: 'N=M' and 'is_homogeneous=0'.
    undistort:
        -1<=_amplitude<=1,_aspect_ratio,_zoom,_center_x[%],_center_y[%],
          _boundary_conditions
        Correct barrel/pincushion distortions occurring with wide-angle lens.
        References:
        [1] Zhang Z. (1999). Flexible camera calibration by viewing a plane from unknown orientation.
        [2] Andrew W. Fitzgibbon (2001). Simultaneous linear estimation of multiple view geometry and
          lens distortion.
        'boundary_conditions' can be { 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }.

        Default values: 'amplitude=0.25', 'aspect_ratio=0', 'zoom=0', 'center_x=center_y=50%' and
          'boundary_conditions=0'.
    unroll (+):
        _axis={ x | y | z | c }
        Unroll selected images along specified axis.
        (eq. to 'y').

        Default value: 'axis=y'.
    upscale_smart:
        width[%],_height[%],_depth,_smoothness>=0,_anisotropy=[0,1],sharpening>=0
        Upscale selected images with an edge-preserving algorithm.

        Default values: 'height=100%', 'depth=100%', 'smoothness=2', 'anisotropy=0.4' and
          'sharpening=10'.
    warp (+):
        [warping_field],_mode,_interpolation,_boundary_conditions,_nb_frames>0
        Warp selected images with specified displacement field.
        'mode' can be { 0=backward-absolute | 1=backward-relative | 2=forward-absolute |
          3=forward-relative }.
        'interpolation' can be { 0=nearest-neighbor | 1=linear | 2=cubic }.
        'boundary_conditions' can be { 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }.

        Default values: 'mode=0', 'interpolation=1', 'boundary_conditions=1' and 'nb_frames=1'.
    warp_patch:
        [warping_field],patch_width>=1,_patch_height>=1,_patch_depth>=1,_std_factor>0,
          _boundary_conditions.
        Patch-warp selected images, with specified 2D or 3D displacement field (in backward-absolute mode).
        Argument 'std_factor' sets the std of the gaussian weights for the patch overlap,
        equal to 'std = std_factor*patch_size'.
        'boundary_conditions' can be { 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }.

        Default values: 'std_factor=0.3' and 'boundary_conditions=3'.
 ** Filtering:
    bandpass:
        _min_freq[%],_max_freq[%]
        Apply bandpass filter to selected images.

        Default values: 'min_freq=0' and 'max_freq=20%'.
    bilateral (+):
        [guide],std_deviation_s[%]>=0,std_deviation_r[%]>=0,_sampling_s>=0,
          _sampling_r>=0 |
        std_deviation_s[%]>=0,std_deviation_r[%]>=0,_sampling_s>=0,_sampling_r>=0
        Blur selected images by anisotropic (eventually joint/cross) bilateral filtering.
        If a guide image is provided, it is used for drive the smoothing filter.
        A guide image must be of the same xyz-size as the selected images.
        Set 'sampling' arguments to '0' for automatic adjustment.
    blur (+):
        std_deviation>=0[%],_boundary_conditions,_kernel |
        axes,std_deviation>=0[%],_boundary_conditions,_kernel
        Blur selected images by a quasi-gaussian or gaussian filter (recursive implementation).
        (eq. to 'b').
        'boundary_conditions' can be { 0=dirichlet | 1=neumann }.
        'kernel' can be { 0=quasi-gaussian (faster) | 1=gaussian }.
        When specified, argument 'axes' is a sequence of { x | y | z | c }.
        Specifying one axis multiple times apply also the blur multiple times.

        Default values: 'boundary_conditions=1' and 'kernel=0'.
    blur_angular:
        amplitude[%],_center_x[%],_center_y[%]
        Apply angular blur on selected images.

        Default values: 'center_x=center_y=50%'.
    blur_bloom:
        _amplitude>=0,_ratio>=0,_nb_iter>=0,_blend_operator={ + | max | min },_kernel={
          0=quasi-gaussian (faster) | 1=gaussian | 2=box | 3=triangle | 4=quadratic },
          _normalize_scales={ 0 | 1 },_axes
        Apply a bloom filter that blend multiple blur filters of different radii,
        resulting in a larger but sharper glare than a simple blur.
        When specified, argument 'axes' is a sequence of { x | y | z | c }.
        Specifying one axis multiple times apply also the blur multiple times.
        Reference: Masaki Kawase, "Practical Implementation of High Dynamic Range Rendering", GDC 2004.

        Default values: 'amplitude=1', 'ratio=2', 'nb_iter=5', 'blend_operator=+', 'kernel=0',
          'normalize_scales=0' and 'axes=(all)'
    blur_linear:
        amplitude1[%],_amplitude2[%],_angle,_boundary_conditions={ 0=dirichlet |
          1=neumann }
        Apply linear blur on selected images, with specified angle and amplitudes.

        Default values: 'amplitude2=0', 'angle=0' and 'boundary_conditions=1'.
    blur_radial:
        amplitude[%],_center_x[%],_center_y[%]
        Apply radial blur on selected images.

        Default values: 'center_x=center_y=50%'.
    blur_selective:
        sigma>=0,_edges>0,_nb_scales>0
        Blur selected images using selective gaussian scales.

        Default values: 'sigma=5', 'edges=0.5' and 'nb_scales=5'.
    blur_x:
        amplitude[%]>=0,_boundary_conditions={ 0=dirichlet | 1=neumann }
        Blur selected images along the x-axis.

        Default value: 'boundary_conditions=1'.
    blur_xy:
        amplitude_x[%],amplitude_y[%],_boundary_conditions={ 0=dirichlet | 1=neumann }
        Blur selected images along the X and Y axes.

        Default value: 'boundary_conditions=1'.
    blur_xyz:
        amplitude_x[%],amplitude_y[%],amplitude_z,_boundary_conditions={ 0=dirichlet |
          1=neumann }
        Blur selected images along the X, Y and Z axes.

        Default value: 'boundary_conditions=1'.
    blur_y:
        amplitude[%]>=0,_boundary_conditions={ 0=dirichlet | 1=neumann }
        Blur selected images along the y-axis.

        Default value: 'boundary_conditions=1'.
    blur_z:
        amplitude[%]>=0,_boundary_conditions={ 0=dirichlet | 1=neumann }
        Blur selected images along the z-axis.

        Default value: 'boundary_conditions=1'.
    boxfilter (+):
        size>=0[%],_order,_boundary_conditions,_nb_iter>=0 |
        axes,size>=0[%],_order,_boundary_conditions,_nb_iter>=0
        Blur selected images by a box filter of specified size (fast recursive implementation).
        'order' can be { 0=smooth | 1=1st-derivative | 2=2nd-derivative }.
        'boundary_conditions' can be { 0=dirichlet | 1=neumann }.
        When specified, argument 'axes' is a sequence of { x | y | z | c }.
        Specifying one axis multiple times apply also the blur multiple times.

        Default values: 'order=0', 'boundary_conditions=1' and 'nb_iter=1'.
    bump2normal:
        Convert selected bumpmaps to normalmaps.
    compose_freq:
        Compose selected low and high frequency parts into new images.
    convolve (+):
        [mask],_boundary_conditions,_is_normalized={ 0 | 1 },_channel_mode,_xcenter,
          _ycenter,_zcenter,_xstart,_ystart,_zstart,_xend,_yend,_zend,_xstride,_ystride,
          _zstride,_xdilation,_ydilation,_zdilation
        Convolve selected images by specified mask.
        'boundary_conditions' can be { 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }.
        'channel_mode' can be { 0=sum input channels | 1=one-for-one | 2=expand }.

        Default values: 'boundary_conditions=1', 'is_normalized=0', 'sum_input_channels=0',
          'xcenter=ycenter=zcenter=-1' (-1=centered), 'xstart=ystart=zstart=0', 'xend=yend=zend=-1'
          (-1=max coordinates), 'xstride=ystride=zstride=1' and 'xdilation=ydilation=zdilation=1'.
    convolve_fft:
        [mask]
        Convolve selected images with specified mask, in the fourier domain.
    correlate (+):
        [mask],_boundary_conditions,_is_normalized={ 0 | 1 },_channel_mode,_xcenter,
          _ycenter,_zcenter,_xstart,_ystart,_zstart,_xend,_yend,_zend,_xstride,_ystride,
          _zstride,_xdilation,_ydilation,_zdilation
        Correlate selected images by specified mask.
        'boundary_conditions' can be { 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }.
        'channel_mode' can be { 0=sum input channels | 1=one-for-one | 2=expand }.

        Default values: 'boundary_conditions=1', 'is_normalized=0', 'sum_input_channels=0',
          'xcenter=ycenter=zcenter=-1' (-1=centered), 'xstart=ystart=zstart=0', 'xend=yend=zend=-1'
          (-1=max coordinates), 'xstride=ystride=zstride=1' and 'xdilation=ydilation=zdilation=1'.
    cross_correlation:
        [mask]
        Compute cross-correlation of selected images with specified mask.
    curvature:
        Compute isophote curvatures on selected images.
    dct:
        _{ x | y | z }...{ x | y | z } |
        (no arg)
        Compute the discrete cosine transform of selected images,
        optionally along the specified axes only.

        Default values: (no arg)
    deblur:
        amplitude[%]>=0,_nb_iter>=0,_dt>=0,_regul>=0,_regul_type={ 0=Tikhonov |
          1=meancurv. | 2=TV }
        Deblur image using a regularized Jansson-Van Cittert algorithm.

        Default values: 'nb_iter=10', 'dt=20', 'regul=0.7' and 'regul_type=1'.
    deblur_goldmeinel:
        sigma>=0,_nb_iter>=0,_acceleration>=0,_kernel_type={ 0=quasi-gaussian (faster) |
           1=gaussian }.
        Deblur selected images using Gold-Meinel algorithm

        Default values: 'nb_iter=8', 'acceleration=1' and 'kernel_type=1'.
    deblur_richardsonlucy:
        sigma>=0, nb_iter>=0, _kernel_type={ 0=quasi-gaussian (faster) | 1=gaussian }.
        Deblur selected images using Richardson-Lucy algorithm.

        Default values: 'nb_iter=50' and 'kernel_type=1'.
    deconvolve_fft:
        [kernel],_regularization>=0
        Deconvolve selected images by specified mask in the fourier space.

        Default value: 'regularization>=0'.
    deinterlace:
        _method={ 0 | 1 }
        Deinterlace selected images ('method' can be { 0=standard or 1=motion-compensated }).

        Default value: 'method=0'.
    denoise (+):
        [guide],std_deviation_s[%]>=0,_std_deviation_r[%]>=0,_patch_size>0,
          _lookup_size>0,_smoothness,_fast_approx={ 0 | 1 } |
        std_deviation_s[%]>=0,_std_deviation_r[%]>=0,_patch_size>0,_lookup_size>0,
          _smoothness,_fast_approx={ 0 | 1 }
        Denoise selected images by non-local patch averaging.

        Default values: 'std_deviation_p=10', 'patch_size=5', 'lookup_size=6' and 'smoothness=1'.
    denoise_haar:
        _threshold>=0,_nb_scales>=0,_cycle_spinning>0
        Denoise selected images using haar-wavelet thresholding with cycle spinning.
        Set 'nb_scales==0' to automatically determine the optimal number of scales.

        Default values: 'threshold=1.4', 'nb_scale=0' and 'cycle_spinning=10'.
    denoise_patchpca:
        _strength>=0,_patch_size>0,_lookup_size>0,_spatial_sampling>0
        Denoise selected images using the patch-pca algorithm.

        Default values: 'patch_size=7', 'lookup_size=11', 'details=1.8' and 'spatial_sampling=5'.
    deriche (+):
        std_deviation>=0[%],order={ 0 | 1 | 2 },axis={ x | y | z | c },
          _boundary_conditions
        Apply Deriche recursive filter on selected images, along specified axis and with
        specified standard deviation, order and boundary conditions.
        'boundary_conditions' can be { 0=dirichlet | 1=neumann }.

        Default value: 'boundary_conditions=1'.
    dilate (+):
        size>=0 |
        size_x>=0,size_y>=0,size_z>=0 |
        [kernel],_boundary_conditions,_is_real={ 0=binary-mode | 1=real-mode }
        Dilate selected images by a rectangular or the specified structuring element.
        'boundary_conditions' can be { 0=dirichlet | 1=neumann }.

        Default values: 'size_z=1', 'boundary_conditions=1' and 'is_real=0'.
    dilate_circ:
        _size>=0,_boundary_conditions,_is_normalized={ 0 | 1 }
        Apply circular dilation of selected images by specified size.

        Default values: 'boundary_conditions=1' and 'is_normalized=0'.
    dilate_oct:
        _size>=0,_boundary_conditions,_is_normalized={ 0 | 1 }
        Apply octagonal dilation of selected images by specified size.

        Default values: 'boundary_conditions=1' and 'is_normalized=0'.
    dilate_threshold:
        size_x>=1,size_y>=1,size_z>=1,_threshold>=0,_boundary_conditions
        Dilate selected images in the (X,Y,Z,I) space.
        'boundary_conditions' can be { 0=dirichlet | 1=neumann }.

        Default values: 'size_y=size_x', 'size_z=1', 'threshold=255' and 'boundary_conditions=1'.
    divergence:
        Compute divergence of selected vector fields.
    dog:
        _sigma1>=0[%],_sigma2>=0[%]
        Compute difference of gaussian on selected images.

        Default values: 'sigma1=2%' and 'sigma2=3%'.
    diffusiontensors:
        _sharpness>=0,0<=_anisotropy<=1,_alpha[%],_sigma[%],is_sqrt={ 0 | 1 }
        Compute the diffusion tensors of selected images for edge-preserving smoothing algorithms.

        Default values: 'sharpness=0.7', 'anisotropy=0.3', 'alpha=0.6', 'sigma=1.1' and 'is_sqrt=0'.
    edges:
        _threshold[%]>=0
        Estimate contours of selected images.

        Default value: 'edges=15%'
    erode (+):
        size>=0 |
        size_x>=0,size_y>=0,_size_z>=0 |
        [kernel],_boundary_conditions,_is_real={ 0=binary-mode | 1=real-mode }
        Erode selected images by a rectangular or the specified structuring element.
        'boundary_conditions' can be { 0=dirichlet | 1=neumann }.

        Default values: 'size_z=1', 'boundary_conditions=1' and 'is_real=0'.
    erode_circ:
        _size>=0,_boundary_conditions,_is_normalized={ 0 | 1 }
        Apply circular erosion of selected images by specified size.

        Default values: 'boundary_conditions=1' and 'is_normalized=0'.
    erode_oct:
        _size>=0,_boundary_conditions,_is_normalized={ 0 | 1 }
        Apply octagonal erosion of selected images by specified size.

        Default values: 'boundary_conditions=1' and 'is_normalized=0'.
    erode_threshold:
        size_x>=1,size_y>=1,size_z>=1,_threshold>=0,_boundary_conditions
        Erode selected images in the (X,Y,Z,I) space.
        'boundary_conditions' can be { 0=dirichlet | 1=neumann }.

        Default values: 'size_y=size_x', 'size_z=1', 'threshold=255' and 'boundary_conditions=1'.
    fft (+):
        _{ x | y | z }...{ x | y | z }
        Compute the direct fourier transform (real and imaginary parts) of selected images,
        optionally along the specified axes only.
    gradient (+):
        { x | y | z }...{ x | y | z },_scheme |
        (no arg)
        Compute the gradient components (first derivatives) of selected images.
        (eq. to 'g').
        'scheme' can be { -1=backward | 0=centered | 1=forward | 2=sobel | 3=rotation-invariant
          (default) | 4=deriche | 5=vanvliet }.
        (no arg) compute all significant 2D/3D components.

        Default value: 'scheme=3'.
    gradient_norm:
        Compute gradient norm of selected images.
    gradient_orientation:
        _dimension={1,2,3}
        Compute N-d gradient orientation of selected images.

        Default value: 'dimension=3'.
    guided (+):
        [guide],radius[%]>=0,regularization[%]>=0 |
        radius[%]>=0,regularization[%]>=0
        Blur selected images by guided image filtering.
        If a guide image is provided, it is used to drive the smoothing process.
        A guide image must be of the same xyz-size as the selected images.
        This command implements the filtering algorithm described in:
        He, Kaiming; Sun, Jian; Tang, Xiaoou, "Guided Image Filtering," Pattern Analysis and Machine
          Intelligence,
        IEEE Transactions on , vol.35, no.6, pp.1397,1409, June 2013
    haar:
        scale>0
        Compute the direct haar multiscale wavelet transform of selected images.
    heat_flow:
        _nb_iter>=0,_dt,_keep_sequence={ 0 | 1 }
        Apply iterations of the heat flow on selected images.

        Default values: 'nb_iter=10', 'dt=30' and 'keep_sequence=0'.
    hessian (+):
        { xx | xy | xz | yy | yz | zz }...{ xx | xy | xz | yy | yz | zz } |
        (no arg)
        Compute the hessian components (second derivatives) of selected images.
        (no arg) compute all significant components.
    idct:
        _{ x | y | z }...{ x | y | z } |
        (no arg)
        Compute the inverse discrete cosine transform of selected images,
        optionally along the specified axes only.

        Default values: (no arg)
    iee:
        Compute gradient-orthogonal-directed 2nd derivative of image(s).
    ifft (+):
        _{ x | y | z }...{ x | y | z }
        Compute the inverse fourier transform (real and imaginary parts) of selected images.
        optionally along the specified axes only.
    ihaar:
        scale>0
        Compute the inverse haar multiscale wavelet transform of selected images.
    ilaplacian:
        { nb_iterations>0 | 0 },_time_step>0,_[initial_estimate]
        Invert selected Laplacian images.
        If given 'nb_iterations' is '0', inversion is done in Fourier space (single iteration),
        otherwise, by applying 'nb_iterations' of a Laplacian-inversion PDE flow (with specified
          'time_step').
        Note that the resulting inversions are just estimation of possible/approximated solutions.

        Default values: 'nb_iterations=0','time_step=10' and '[initial_estimated]=(undefined)'.
    inn:
        Compute gradient-directed 2nd derivative of image(s).
    inpaint (+):
        [mask] |
        [mask],0,_fast_method |
        [mask],_patch_size>=1,_lookup_size>=1,_lookup_factor>=0,_lookup_increment!=0,
          _blend_size>=0,0<=_blend_threshold<=1,_blend_decay>=0,_blend_scales>=1,
          _is_blend_outer={ 0 | 1 }
        Inpaint selected images by specified mask.
        If no patch size (or 0) is specified, inpainting is done using a fast average or median
          algorithm.
        Otherwise, it used a patch-based reconstruction method, that can be very time consuming.
        'fast_method' can be { 0=low-connectivity average | 1=high-connectivity average |
          2=low-connectivity median | 3=high-connectivity median }.

        Default values: 'patch_size=0', 'fast_method=1', 'lookup_size=22', 'lookup_factor=0.5',
          'lookup_increment=1', 'blend_size=0', 'blend_threshold=0', 'blend_decay=0.05',
          'blend_scales=10' and 'is_blend_outer=1'.
    inpaint_pde:
        [mask],_nb_scales[%]>=0,_diffusion_type={ 0=isotropic | 1=delaunay-guided |
          2=edge-guided | 3=mask-guided },_diffusion_iter>=0
        Inpaint selected images by specified mask using a multiscale transport-diffusion algorithm.
        If 'diffusion type==3', non-zero values of the mask (e.g. a distance function) are used
        to guide the diffusion process.

        Default values: 'nb_scales=75%', 'diffusion_type=1' and 'diffusion_iter=20'.
    inpaint_flow:
        [mask],_nb_global_iter>=0,_nb_local_iter>=0,_dt>0,_alpha>=0,_sigma>=0
        Apply iteration of the inpainting flow on selected images.

        Default values: 'nb_global_iter=10', 'nb_local_iter=100', 'dt=5', 'alpha=1' and 'sigma=3'.
    inpaint_holes:
        maximal_area[%]>=0,_tolerance>=0,_is_high_connectivity={ 0 | 1 }
        Inpaint all connected regions having an area less than specified value.

        Default values: 'maximal_area=4', 'tolerance=0' and 'is_high_connectivity=0'.
    inpaint_morpho:
        [mask]
        Inpaint selected images by specified mask using morphological operators.
    inpaint_matchpatch:
        [mask],_nb_scales={ 0=auto | >0 },_patch_size>0,_nb_iterations_per_scale>0,
          _blend_size>=0,_allow_outer_blending={ 0 | 1 },_is_already_initialized={ 0 | 1 }
        Inpaint selected images by specified binary mask, using a multi-scale matchpatch algorithm.

        Default values: 'nb_scales=0', 'patch_size=9', 'nb_iterations_per_scale=10', 'blend_size=5',
          'allow_outer_blending=1' and 'is_already_initialized=0'.
    kuwahara:
        size>0
        Apply Kuwahara filter of specified size on selected images.
    laplacian:
        Compute Laplacian of selected images.
    lic:
        _amplitude>0,_channels>0
        Render LIC representation of selected vector fields.

        Default values: 'amplitude=30' and 'channels=1'.
    map_tones:
        _threshold>=0,_gamma>=0,_smoothness>=0,nb_iter>=0
        Apply tone mapping operator on selected images, based on Poisson equation.

        Default values: 'threshold=0.1', 'gamma=0.8', 'smoothness=0.5' and 'nb_iter=30'.
    map_tones_fast:
        _radius[%]>=0,_power>=0
        Apply fast tone mapping operator on selected images.

        Default values: 'radius=3%' and 'power=0.3'.
    meancurvature_flow:
        _nb_iter>=0,_dt,_keep_sequence={ 0 | 1 }
        Apply iterations of the mean curvature flow on selected images.

        Default values: 'nb_iter=10', 'dt=30' and 'keep_sequence=0'.
    median (+):
        size>=0,_threshold>0
        Apply (opt. thresholded) median filter on selected images with structuring element size x size.
    nlmeans:
        [guide],_patch_radius>0,_spatial_bandwidth>0,_tonal_bandwidth>0,
          _patch_measure_command |
        _patch_radius>0,_spatial_bandwidth>0,_tonal_bandwidth>0,_patch_measure_command
        Apply non local means denoising of Buades et al, 2005. on selected images.
        The patch is a gaussian function of 'std _patch_radius'.
        The spatial kernel is a rectangle of radius 'spatial_bandwidth'.
        The tonal kernel is exponential (exp(-d^2/_tonal_bandwidth^2))
        with d the euclidiean distance between image patches.

        Default values: 'patch_radius=4', 'spatial_bandwidth=4', 'tonal_bandwidth=10' and
          'patch_measure_command=-norm'.
    nlmeans_core:
        _reference_image,_scaling_map,_patch_radius>0,_spatial_bandwidth>0
        Apply non local means denoising using a image for weight and a map for scaling
    normalize_local:
        _amplitude>=0,_radius>0,_n_smooth>=0[%],_a_smooth>=0[%],_is_cut={ 0 | 1 },
          _min=0,_max=255
        Normalize selected images locally.

        Default values: 'amplitude=3', 'radius=16', 'n_smooth=4%', 'a_smooth=2%', 'is_cut=1', 'min=0'
          and 'max=255'.
    normalized_cross_correlation:
        [mask]
        Compute normalized cross-correlation of selected images with specified mask.
    peronamalik_flow:
        K_factor>0,_nb_iter>=0,_dt,_keep_sequence={ 0 | 1 }
        Apply iterations of the Perona-Malik flow on selected images.

        Default values: 'K_factor=20', 'nb_iter=5', 'dt=5' and 'keep_sequence=0'.
    phase_correlation:
        [destination]
        Estimate translation vector between selected source images and specified destination.
    pde_flow:
        _nb_iter>=0,_dt,_velocity_command,_keep_sequence={ 0 | 1 }
        Apply iterations of a generic PDE flow on selected images.

        Default values: 'nb_iter=10', 'dt=30', 'velocity_command=laplacian' and 'keep_sequence=0'.
    periodize_poisson:
        Periodize selected images using a Poisson solver in Fourier space.
    red_eye:
        0<=_threshold<=100,_smoothness>=0,0<=attenuation<=1
        Attenuate red-eye effect in selected images.

        Default values: 'threshold=75', 'smoothness=3.5' and 'attenuation=0.1'.
    remove_hotpixels:
        _mask_size>0, _threshold[%]>0
        Remove hot pixels in selected images.

        Default values: 'mask_size=3' and 'threshold=10%'.
    remove_pixels:
        number_of_pixels[%]>=0
        Remove specified number of pixels (i.e. set them to 0) from the set of non-zero pixels in
          selected images.
    rolling_guidance:
        std_deviation_s[%]>=0,std_deviation_r[%]>=0,_precision>=0
        Apply the rolling guidance filter on selected image.
        Rolling guidance filter is a fast image abstraction filter, described in:
        "Rolling Guidance Filter", Qi Zhang Xiaoyong, Shen Li, Xu Jiaya Jia, ECCV'2014.

        Default values: 'std_deviation_s=4', 'std_deviation_r=10' and 'precision=0.5'.
    sharpen (+):
        amplitude>=0 |
        amplitude>=0,edge>=0,_alpha,_sigma
        Sharpen selected images by inverse diffusion or shock filters methods.
        'edge' must be specified to enable shock-filter method.

        Default values: 'alpha=0' and 'sigma=0'.
    smooth (+):
        amplitude[%]>=0,_sharpness>=0,0<=_anisotropy<=1,_alpha[%],_sigma[%],_dl>0,_da>0,
          _precision>0,_interpolation,_fast_approx={ 0 | 1 } |
        nb_iterations>=0,_sharpness>=0,_anisotropy,_alpha,_sigma,_dt>0,0 |
        [tensor_field],_amplitude>=0,_dl>0,_da>0,_precision>0,_interpolation,
          _fast_approx={ 0 | 1 } |
        [tensor_field],_nb_iters>=0,_dt>0,0
        Smooth selected images anisotropically using diffusion PDE's, with specified field of
        diffusion tensors.
        'interpolation' can be { 0=nearest | 1=linear | 2=runge-kutta }.

        Default values: 'sharpness=0.7', 'anisotropy=0.3', 'alpha=0.6', 'sigma=1.1', 'dl=0.8', 'da=30',
          'precision=2', 'interpolation=0' and 'fast_approx=1'.
    split_freq:
        smoothness>0[%]
        Split selected images into low and high frequency parts.
    solve_poisson:
        "laplacian_command",_nb_iterations>=0,_time_step>0,_nb_scales>=0
        Solve Poisson equation so that applying 'laplacian[n]' is close to the result of
          'laplacian_command[n]'.
        Solving is performed using a multi-scale gradient descent algorithm.
        If 'nb_scales=0', the number of scales is automatically determined.

        Default values: 'nb_iterations=60', 'dt=5' and 'nb_scales=0'.
    split_details:
        _nb_scales>0,_base_scale[%]>=0,_detail_scale[%]>=0
        Split selected images into 'nb_scales' detail scales.
        If 'base_scale'=='detail_scale'==0, the image decomposition is done with 'a trous' wavelets.
        Otherwise, it uses laplacian pyramids with linear standard deviations.

        Default values: 'nb_scales=4', 'base_scale=0' and 'detail_scale=0'.
    structuretensors (+):
        _scheme={ 0=centered | 1=forward/backward }
        Compute the structure tensor field of selected images.

        Default value: 'scheme=1'.
    solidify:
        _smoothness[%]>=0,_diffusion_type={ 0=isotropic | 1=delaunay-oriented |
          2=edge-oriented },_diffusion_iter>=0
        Solidify selected transparent images.

        Default values: 'smoothness=75%', 'diffusion_type=1' and 'diffusion_iter=20'.
    syntexturize:
        _width[%]>0,_height[%]>0
        Resynthetize 'width'x'height' versions of selected micro-textures by phase randomization.
        The texture synthesis algorithm is a straightforward implementation of the method described in :
        http://www.ipol.im/pub/art/2011/ggm_rpn/

        Default values: 'width=height=100%'.
    syntexturize_matchpatch:
        _width[%]>0,_height[%]>0,_nb_scales>=0,_patch_size>0,_blending_size>=0,
          _precision>=0
        Resynthetize 'width'x'height' versions of selected micro-textures using a patch-matching
          algorithm.
        If 'nbscales==0', the number of scales used is estimated from the image size.

        Default values: 'width=height=100%', 'nb_scales=0', 'patch_size=7', 'blending_size=5' and
          'precision=1'.
    tv_flow:
        _nb_iter>=0,_dt,_keep_sequence={ 0 | 1 }
        Apply iterations of the total variation flow on selected images.

        Default values: 'nb_iter=10', 'dt=30' and 'keep_sequence=0'.
    unsharp:
        radius[%]>=0,_amount>=0,_threshold[%]>=0
        Apply unsharp mask on selected images.

        Default values: 'amount=2' and 'threshold=0'.
    unsharp_octave:
        _nb_scales>0,_radius[%]>=0,_amount>=0,threshold[%]>=0
        Apply octave sharpening on selected images.

        Default values: 'nb_scales=4', 'radius=1', 'amount=2' and 'threshold=0'.
    vanvliet (+):
        std_deviation>=0[%],order={ 0 | 1 | 2 | 3 },axis={ x | y | z | c },
          _boundary_conditions
        Apply Vanvliet recursive filter on selected images, along specified axis and with
        specified standard deviation, order and boundary conditions.
        'boundary_conditions' can be { 0=dirichlet | 1=neumann }.

        Default value: 'boundary_conditions=1'.
    voronoi:
        Compute the discrete Voronoi diagram of non-zero pixels in selected images.
    watermark_fourier:
        text,_size>0
        Add a textual watermark in the frequency domain of selected images.

        Default value: 'size=33'.
    watershed (+):
        [priority_image],_is_high_connectivity={ 0 | 1 }
        Compute the watershed transform of selected images.

        Default value: 'is_high_connectivity=1'.
 ** Features Extraction:
    area:
        tolerance>=0,is_high_connectivity={ 0 | 1 }
        Compute area of connected components in selected images.

        Default values: 'is_high_connectivity=0'.
    area_fg:
        tolerance>=0,is_high_connectivity={ 0 | 1 }
        Compute area of connected components for non-zero values in selected images.
        Similar to 'area' except that 0-valued pixels are not considered.

        Default values: 'is_high_connectivity=0'.
    at_line:
        x0[%],y0[%],z0[%],x1[%],y1[%],z1[%]
        Retrieve pixels of the selected images belonging to the specified line (x0,y0,z0)-(x1,y1,z1).
    at_quadrangle:
        x0[%],y0[%],x1[%],y1[%],x2[%],y2[%],x3[%],y3[%],_interpolation,
          _boundary_conditions |
        x0[%],y0[%],z0[%],x1[%],y1[%],z1[%],x2[%],y2[%],z2[%],x3[%],y3[%],z3[%],
          _interpolation,_boundary_conditions
        Retrieve pixels of the selected images belonging to the specified 2D or 3D quadrangle.
        'interpolation' can be { 0=nearest-neighbor | 1=linear | 2=cubic }.
        'boundary_conditions' can be { 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }.
    barycenter:
        Compute the barycenter vector of pixel values.
    delaunay:
        Generate discrete 2D Delaunay triangulation of non-zero pixels in selected images.
        Input images must be scalar.
        Each pixel of the output image is a triplet (a,b,c) meaning the pixel belongs to
        the Delaunay triangle 'ABC' where 'a','b','c' are the labels of the pixels 'A','B','C'.
    detect_skin:
        0<=tolerance<=1,_skin_x,_skin_y,_skin_radius>=0
        Detect skin in selected color images and output an appartenance probability map.
        Detection is performed using CbCr chromaticity data of skin pixels.
        If arguments 'skin_x', 'skin_y' and 'skin_radius' are provided, skin pixels are learnt
        from the sample pixels inside the circle located at ('skin_x','skin_y') with radius
          'skin_radius'.

        Default value: 'tolerance=0.5' and 'skin_x=skiny=radius=-1'.
    displacement (+):
        [source_image],_smoothness,_precision>=0,_nb_scales>=0,_iteration_max>=0,
          is_backward={ 0 | 1 },_[guide]
        Estimate displacement field between specified source and selected target images.
        If 'smoothness>=0', regularization type is set to isotropic, else to anisotropic.
        If 'nbscales==0', the number of scales used is estimated from the image size.

        Default values: 'smoothness=0.1', 'precision=5', 'nb_scales=0', 'iteration_max=10000',
          'is_backward=1' and '[guide]=(unused)'.
    distance (+):
        isovalue[%],_metric |
        isovalue[%],[metric],_method
        Compute the unsigned distance function to specified isovalue, opt. according to a custom metric.
        'metric' can be { 0=chebyshev | 1=manhattan | 2=euclidean | 3=squared-euclidean }.
        'method' can be { 0=fast-marching | 1=low-connectivity dijkstra | 2=high-connectivity dijkstra |
           3=1+return path | 4=2+return path }.

        Default value: 'metric=2' and 'method=0'.
    fftpolar:
        Compute fourier transform of selected images, as centered magnitude/phase images.
    histogram (+):
        _nb_levels>0[%],_value0[%],_value1[%]
        Compute the histogram of selected images.
        If value range is set, the histogram is estimated only for pixels in the specified
        value range. Argument 'value1' must be specified if 'value0' is set.

        Default values: 'nb_levels=256', 'value0=0%' and 'value1=100%'.
    histogram_nd:
        nb_levels>0[%],_value0[%],_value1[%]
        Compute the 1D,2D or 3D histogram of selected multi-channels images (having 1,2 or 3 channels).
        If value range is set, the histogram is estimated only for pixels in the specified
        value range.

        Default values: 'value0=0%' and 'value1=100%'.
    histogram_cumul:
        _nb_levels>0,_is_normalized={ 0 | 1 },_val0[%],_val1[%]
        Compute cumulative histogram of selected images.

        Default values: 'nb_levels=256', 'is_normalized=0', 'val0=0%' and 'val1=100%'.
    histogram_pointwise:
        nb_levels>0[%],_value0[%],_value1[%]
        Compute the histogram of each vector-valued point of selected images.
        If value range is set, the histogram is estimated only for values in the specified
        value range.

        Default values: 'value0=0%' and 'value1=100%'.
    hough:
        _width>0,_height>0,gradient_norm_voting={ 0 | 1 }
        Compute hough transform (theta,rho) of selected images.

        Default values: 'width=512', 'height=width' and 'gradient_norm_voting=1'.
    ifftpolar:
        Compute inverse fourier transform of selected images, from centered magnitude/phase images.
    isophotes:
        _nb_levels>0
        Render isophotes of selected images on a transparent background.

        Default value: 'nb_levels=64'
    label (+):
        _tolerance>=0,is_high_connectivity={ 0 | 1 }
        Label connected components in selected images.

        Default values: 'tolerance=0' and 'is_high_connectivity=0'.
    label_fg:
        tolerance>=0,is_high_connectivity={ 0 | 1 }
        Label connected components for non-zero values (foreground) in selected images.
        Similar to 'label' except that 0-valued pixels are not labeled.

        Default value: 'is_high_connectivity=0'.
    max_patch:
        _patch_size>=1
        Return locations of maximal values in local patch-based neighborhood of given size for selected images.

        Default value: 'patch_size=16'.
    min_patch:
        _patch_size>=1
        Return locations of minimal values in local patch-based neighborhood of given size for selected images.

        Default value: 'patch_size=16'.
    minimal_path:
        x0[%]>=0,y0[%]>=0,z0[%]>=0,x1[%]>=0,y1[%]>=0,z1[%]>=0,_is_high_connectivity={ 0 | 1 }
        Compute minimal path between two points on selected potential maps.

        Default value: 'is_high_connectivity=0'.
    mse (+):
        Compute MSE (Mean-Squared Error) matrix between selected images.
    patches:
        patch_width>0,patch_height>0,patch_depth>0,x0,y0,z0,_x1,_y1,_z1,...,_xN,_yN,_zN
        Extract N+1 patches from selected images, centered at specified locations.
    matchpatch (+):
        [patch_image],patch_width>=1,_patch_height>=1,_patch_depth>=1,_nb_iterations>=0,
          _nb_randoms>=0,_occ_penalization,_output_score={ 0 | 1 },_[guide]
        Estimate correspondence map between selected images and specified patch image, using
        a patch-matching algorithm.
        Each pixel of the returned correspondence map gives the location (p,q) of the closest patch in
        the specified patch image. If 'output_score=1', the third channel also gives the corresponding
        matching score for each patch as well.

        Default values: 'patch_height=patch_width', 'patch_depth=1', 'nb_iterations=5', 'nb_randoms=5',
          'occ_penalization=0', 'output_score=0' and 'guide=(undefined)'.
    plot2value:
        Retrieve values from selected 2D graph plots.
    pointcloud:
        _type = { -X=-X-opacity | 0=binary | 1=cumulative | 2=label | 3=retrieve
          coordinates },_width,_height>0,_depth>0
        Render a set of point coordinates, as a point cloud in a 1D/2D or 3D binary image
        (or do the reverse, i.e. retrieve coordinates of non-zero points from a rendered point cloud).
        Input point coordinates can be a NxMx1x1, Nx1x1xM or 1xNx1xM image, where 'N' is the number of points,
        and M the point coordinates.
        If 'M'>3, the 3-to-M components sets the (M-3)-dimensional color at each point.
        Parameters 'width','height' and 'depth' are related to the size of the final image :
        - If set to 0, the size is automatically set along the specified axis.
        - If set to N>0, the size along the specified axis is N.
        - If set to N<0, the size along the specified axis is at most N.
        Points with coordinates that are negative or higher than specified ('width','height','depth')
        are not plotted.

        Default values: 'type=0' and 'max_width=max_height=max_depth=0'.
    psnr:
        _max_value
        Compute PSNR (Peak Signal-to-Noise Ratio) matrix between selected images.

        Default value: 'max_value=255'.
    segment_watershed:
        _threshold>=0
        Apply watershed segmentation on selected images.

        Default values: 'threshold=2'.
    shape2bump:
        _resolution>=0,0<=_weight_avg_max_avg<=1,_dilation,_smoothness>=0
        Estimate bumpmap from binary shape in selected images.

        Default value: 'resolution=256', 'weight_avg_max=0.75', 'dilation=0' and 'smoothness=100'.
    skeleton:
        _boundary_conditions={ 0=dirichlet | 1=neumann }
        Compute skeleton of binary shapes using distance transform and constrained thinning.

        Default value: 'boundary_conditions=1'.
    slic:
        size>0,_regularity>=0,_nb_iterations>0
        Segment selected 2D images with superpixels, using the SLIC algorithm (Simple Linear Iterative
          Clustering).
        Scalar images of increasingly labeled pixels are returned.
        Reference paper: Achanta, R., Shaji, A., Smith, K., Lucchi, A., Fua, P., & Süsstrunk, S.
          (2010). SLIC Superpixels (No. EPFL-REPORT-149300).

        Default values: 'size=16', 'regularity=10' and 'nb_iterations=10'.
    ssd_patch:
        [patch],_use_fourier={ 0 | 1 },_boundary_conditions={ 0=dirichlet | 1=neumann }
        Compute fields of SSD between selected images and specified patch.
        Argument 'boundary_conditions' is valid only when 'use_fourier=0'.

        Default value: 'use_fourier=0' and 'boundary_conditions=0'.
    thinning:
        _boundary_conditions={ 0=dirichlet | 1=neumann }
        Compute skeleton of binary shapes using morphological thinning
        (beware, this is a quite slow iterative process)

        Default value: 'boundary_conditions=1'.
    tones:
        N>0
        Get N tones masks from selected images.
    topographic_map:
        _nb_levels>0,_smoothness
        Render selected images as topographic maps.

        Default values: 'nb_levels=16' and 'smoothness=2'.
    tsp:
        _precision>=0
        Try to solve the 'travelling salesman' problem, using a combination of greedy search and 2-opt
          algorithms.
        Selected images must have dimensions Nx1x1xC to represent N cities each with C-dimensional
          coordinates.
        This command re-order the selected data along the x-axis so that the point sequence becomes a
          shortest path.

        Default values: 'precision=256'.
    variance_patch:
        _patch_size>=1
        Compute variance of each images patch centered at (x,y), in selected images.

        Default value: 'patch_size=16'
 ** Image Drawing:
    arrow:
        x0[%],y0[%],x1[%],y1[%],_thickness[%]>=0,_head_length[%]>=0,
          _head_thickness[%]>=0,_opacity,_pattern,_color1,...
        Draw specified arrow on selected images.
        'pattern' is an hexadecimal number starting with '0x' which can be omitted
        even if a color is specified. If a pattern is specified, the arrow is
        drawn outlined instead of filled.

        Default values: 'thickness=1%', 'head_length=10%', 'head_thickness=3%', 'opacity=1',
          'pattern=(undefined)' and 'color1=0'.
    axes:
        x0,x1,y0,y1,_font_height>=0,_opacity,_pattern,_color1,...
        Draw xy-axes on selected images.
        'pattern' is an hexadecimal number starting with '0x' which can be omitted
        even if a color is specified.
        To draw only one x-axis at row Y, set both 'y0' and 'y1' to Y.
        To draw only one y-axis at column X, set both 'x0' and 'x1' to X.

        Default values: 'font_height=14', 'opacity=1', 'pattern=(undefined)' and 'color1=0'.
    ball:
        _size>0, _R,_G,_B,0<=_specular_light<=8,0<=_specular_size<=8,_shadow>=0
        Input a 2D RGBA colored ball sprite.

        Default values: 'size=64', 'R=255', 'G=R', 'B=R', 'specular_light=0.8', 'specular_size=1' and
          'shading=1.5'.
    chessboard:
        size1>0,_size2>0,_offset1,_offset2,_angle,_opacity,_color1,...,_color2,...
        Draw chessboard on selected images.

        Default values: 'size2=size1', 'offset1=offset2=0', 'angle=0', 'opacity=1', 'color1=0' and
          'color2=255'.
    cie1931:
        Draw CIE-1931 chromaticity diagram on selected images.
    circle:
        x[%],y[%],R[%],_opacity,_pattern,_color1,...
        Draw specified colored circle on selected images.
        A radius of '100%' stands for 'sqrt(width^2+height^2)'.
        'pattern' is an hexadecimal number starting with '0x' which can be omitted
        even if a color is specified. If a pattern is specified, the circle is
        drawn outlined instead of filled.

        Default values: 'opacity=1', 'pattern=(undefined)' and 'color1=0'.
    close_binary:
        0<=_endpoint_rate<=100,_endpoint_connectivity>=0,_spline_distmax>=0,
          _segment_distmax>=0,0<=_spline_anglemax<=180,_spline_roundness>=0,_area_min>=0,
          _allow_self_intersection={ 0 | 1 }
        Automatically close open shapes in binary images (defining white strokes on black background).

        Default values: 'endpoint_rate=75', 'endpoint_connectivity=2', 'spline_distmax=80',
          'segment_distmax=20', 'spline_anglemax=90', 'spline_roundness=1','area_min=100',
          'allow_self_intersection=1'.
    ellipse (+):
        x[%],y[%],R[%],r[%],_angle,_opacity,_pattern,_color1,...
        Draw specified colored ellipse on selected images.
        A radius of '100%' stands for 'sqrt(width^2+height^2)'.
        'pattern' is an hexadecimal number starting with '0x' which can be omitted
        even if a color is specified. If a pattern is specified, the ellipse is
        drawn outlined instead of filled.

        Default values: 'opacity=1', 'pattern=(undefined)' and 'color1=0'.
    flood (+):
        x[%],_y[%],_z[%],_tolerance>=0,_is_high_connectivity={ 0 | 1 },_opacity,_color1,...
        Flood-fill selected images using specified value and tolerance.

        Default values: 'y=z=0', 'tolerance=0', 'is_high_connectivity=0', 'opacity=1' and 'color1=0'.
    gaussian:
        _sigma1[%],_sigma2[%],_angle
        Draw a centered gaussian on selected images, with specified standard deviations and orientation.

        Default values: 'sigma1=3', 'sigma2=sigma1' and 'angle=0'.
    graph (+):
        [function_image],_plot_type,_vertex_type,_ymin,_ymax,_opacity,_pattern,_color1,... |
        'formula',_resolution>=0,_plot_type,_vertex_type,_xmin,xmax,_ymin,_ymax,
          _opacity,_pattern,_color1,...
        Draw specified function graph on selected images.
        'plot_type' can be { 0=none | 1=lines | 2=splines | 3=bar }.
        'vertex_type' can be { 0=none | 1=points | 2,3=crosses | 4,5=circles | 6,7=squares }.
        'pattern' is an hexadecimal number starting with '0x' which can be omitted
        even if a color is specified.

        Default values: 'plot_type=1', 'vertex_type=1', 'ymin=ymax=0 (auto)', 'opacity=1',
          'pattern=(undefined)'
        and 'color1=0'.
    grid:
        size_x[%]>=0,size_y[%]>=0,_offset_x[%],_offset_y[%],_opacity,_pattern,_color1,...
        Draw xy-grid on selected images.
        'pattern' is an hexadecimal number starting with '0x' which can be omitted
        even if a color is specified.

        Default values: 'offset_x=offset_y=0', 'opacity=1', 'pattern=(undefined)' and 'color1=0'.
    image (+):
        [sprite],_x[%|~],_y[%|~],_z[%|~],_c[%|~],_opacity,_[opacity_mask],
          _max_opacity_mask
        Draw specified sprite image on selected images.
        (eq. to 'j').
        If one of the x,y,z or c argument ends with a '~', its value is expected to be
        a centering ratio (in [0,1]) rather than a position.
        Usual centering ratio are { 0=left-justified | 0.5=centered | 1=right-justified }.

        Default values: 'x=y=z=c=0', 'opacity=1', 'opacity_mask=(undefined)' and 'max_opacity_mask=1'.
    line (+):
        x0[%],y0[%],x1[%],y1[%],_opacity,_pattern,_color1,...
        Draw specified colored line on selected images.
        'pattern' is an hexadecimal number starting with '0x' which can be omitted
        even if a color is specified.

        Default values: 'opacity=1', 'pattern=(undefined)' and 'color1=0'.
    linethick:
        x0[%],y0[%],x1[%],y1[%],_thickness,_opacity,_color1
        Draw specified colored thick line on selected images.

        Default values: 'thickness=2', 'opacity=1' and 'color1=0'.
    mandelbrot (+):
        z0r,z0i,z1r,z1i,_iteration_max>=0,_is_julia={ 0 | 1 },_c0r,_c0i,_opacity
        Draw mandelbrot/julia fractal on selected images.

        Default values: 'iteration_max=100', 'is_julia=0', 'c0r=c0i=0' and 'opacity=1'.
    marble:
        _image_weight,_pattern_weight,_angle,_amplitude,_sharpness>=0,_anisotropy>=0,
          _alpha,_sigma,_cut_low>=0,_cut_high>=0
        Render marble like pattern on selected images.

        Default values: 'image_weight=0.2', 'pattern_weight=0.1', 'angle=45', 'amplitude=0',
          'sharpness=0.4' and 'anisotropy=0.8',
        'alpha=0.6', 'sigma=1.1' and 'cut_low=cut_high=0'.
    maze:
        _width>0,_height>0,_cell_size>0
        Input maze with specified size.
    maze_mask:
        _cellsize>0
        Input maze according to size and shape of selected mask images.
        Mask may contain disconnected shapes.
    object3d (+):
        [object3d],_x[%],_y[%],_z,_opacity,_rendering_mode,_is_double_sided={ 0 | 1 },
          _is_zbuffer={ 0 | 1 },_focale,_light_x,_light_y,_light_z,_specular_lightness,
          _specular_shininess
        Draw specified 3D object on selected images.
        (eq. to 'j3d').
        'rendering_mode' can be { 0=dots | 1=wireframe | 2=flat | 3=flat-shaded | 4=gouraud-shaded |
          5=phong-shaded }.

        Default values: 'x=y=z=0', 'opacity=1' and 'is_zbuffer=1'. All other arguments take their
          default values
        from the 3D environment variables.
    pack_sprites:
        _nb_scales>=0,0<=_min_scale<=100,_allow_rotation={ 0=0 deg. | 1=180 deg. | 2=90
          deg. | 3=any },_spacing,_precision>=0,max_iterations>=0
        Try to randomly pack as many sprites as possible onto the 'empty' areas of an image.
        Sprites can be eventually rotated and scaled during the packing process.
        First selected image is the canvas that will be filled with the sprites.
        Its last channel must be a binary mask whose zero values represent potential locations for
          drawing the sprites.
        All other selected images represent the sprites considered for packing.
        Their last channel must be a binary mask that represents the sprite shape (i.e. a 8-connected
          component).
        The order of sprite packing follows the order of specified sprites in the image list.
        Sprite packing is done on random locations and iteratively with decreasing scales.
        'nb_scales' sets the number of decreasing scales considered for all specified sprites to be packed.
        'min_scale' (in %) sets the minimal size considered for packing (specified as a percentage of the
        original sprite size).
        'spacing' can be positive or negative.
        'precision' tells about the desired number of failed trials before ending the filling process.

        Default values: 'nb_scales=5', 'min_scale=25', 'allow_rotation=3', 'spacing=1', 'precision=7'
          and 'max_iterations=256'.
    piechart:
        label_height>=0,label_R,label_G,label_B,"label1",value1,R1,G1,B1,...,"labelN",
          valueN,RN,GN,BN
        Draw pie chart on selected (RGB) images.
    plasma (+):
        _alpha,_beta,_scale>=0
        Draw a random colored plasma fractal on selected images.
        This command implements the so-called 'Diamond-Square' algorithm.

        Default values: 'alpha=1', 'beta=1' and 'scale=8'.
    point (+):
        x[%],y[%],_z[%],_opacity,_color1,...
        Set specified colored pixel on selected images.

        Default values: 'z=0', 'opacity=1' and 'color1=0'.
    polka_dots:
        diameter>=0,_density,_offset1,_offset2,_angle,_aliasing,_shading,_opacity,
          _color,...
        Draw dots pattern on selected images.

        Default values: 'density=20', 'offset1=offset2=50', 'angle=0', 'aliasing=10', 'shading=1',
          'opacity=1' and 'color=255'.
    polygon (+):
        N>=1,x1[%],y1[%],...,xN[%],yN[%],_opacity,_pattern,_color1,...
        Draw specified colored N-vertices polygon on selected images.
        'pattern' is an hexadecimal number starting with '0x' which can be omitted
        even if a color is specified. If a pattern is specified, the polygon is
        drawn outlined instead of filled.

        Default values: 'opacity=1', 'pattern=(undefined)' and 'color1=0'.
    quiver:
        [function_image],_sampling[%]>0,_factor>=0,_is_arrow={ 0 | 1 },_opacity,_color1,...
        Draw specified 2D vector/orientation field on selected images.

        Default values: 'sampling=5%', 'factor=1', 'is_arrow=1', 'opacity=1', 'pattern=(undefined)'
        and 'color1=0'.
    rectangle:
        x0[%],y0[%],x1[%],y1[%],_opacity,_pattern,_color1,...
        Draw specified colored rectangle on selected images.
        'pattern' is an hexadecimal number starting with '0x' which can be omitted
        even if a color is specified. If a pattern is specified, the rectangle is
        drawn outlined instead of filled.

        Default values: 'opacity=1', 'pattern=(undefined)' and 'color1=0'.
    rorschach:
        'smoothness[%]>=0','mirroring={ 0=none | 1=x | 2=y | 3=xy }
        Render rorschach-like inkblots on selected images.

        Default values: 'smoothness=5%' and 'mirroring=1'.
    sierpinski:
        recursion_level>=0
        Draw Sierpinski triangle on selected images.

        Default value: 'recursion_level=7'.
    spiralbw:
        width>0,_height>0,_is_2dcoords={ 0 | 1 }
        Input a 2D rectangular spiral image with specified size.

        Default values: 'height=width' and 'is_2dcoords=0'.
    spline:
        x0[%],y0[%],u0[%],v0[%],x1[%],y1[%],u1[%],v1[%],_opacity,_color1,...
        Draw specified colored spline curve on selected images (cubic hermite spline).

        Default values: 'opacity=1' and 'color1=0'.
    tetraedron_shade:
        x0,y0,z0,x1,y1,z1,x2,y2,z2,x3,y3,z3,R0,G0,B0,...,R1,G1,B1,...,R2,G2,B2,...,R3,G3,B3,...
        Draw tetraedron with interpolated colors on selected (volumetric) images.
    text (+):
        text,_x[%|~],_y[%|~],_font_height[%]>=0,_opacity,_color1,...
        Draw specified colored text string on selected images.
        (eq. to 't').
        If one of the x or y argument ends with a '~', its value is expected to be
        a centering ratio (in [0,1]) rather than a position.
        Usual centering ratio are { 0=left-justified | 0.5=centered | 1=right-justified }.
        Sizes '13' and '128' are special and correspond to binary fonts (no-antialiasing).
        Any other font size is rendered with anti-aliasing.
        Specifying an empty target image resizes it to new dimensions such that the image contains
        the entire text string.

        Default values: 'x=y=0.01~', 'font_height=16', 'opacity=1' and 'color1=0'.
    text_outline:
        text,_x[%|~],_y[%|~],_font_height[%]>0,_outline>=0,_opacity,_color1,...
        Draw specified colored and outlined text string on selected images.
        If one of the x or y argument ends with a '~', its value is expected to be
        a centering ratio (in [0,1]) rather than a position.
        Usual centering ratio are { 0=left-justified | 0.5=centered | 1=right-justified }.

        Default values: 'x=y=0.01~', 'font_height=7.5%', 'outline=2', 'opacity=1',
          'color1=color2=color3=255' and 'color4=255'.
    triangle_shade:
        x0,y0,x1,y1,x2,y2,R0,G0,B0,...,R1,G1,B1,...,R2,G2,B2,...
        Draw triangle with interpolated colors on selected images.
    truchet:
        _scale>0,_radius>=0,_pattern_type={ 0=straight | 1=curved }
        Fill selected images with random truchet patterns.

        Default values: 'scale=32', 'radius=5' and 'pattern_type=1'.
    turbulence:
        _radius>0,_octaves={1,2,3...,12},_alpha>0,_difference={-10,10},_mode={0,1,2,3}
        Render fractal noise or turbulence on selected images.

        Default values: 'radius=32', 'octaves=6', 'alpha=3', 'difference=0' and 'mode=0'.
    yinyang:
        Draw a yin-yang symbol on selected images.
 ** Matrix Computation:
    dijkstra (+):
        starting_node>=0,ending_node>=0
        Compute minimal distances and paths from specified adjacency matrices by the Dijkstra algorithm.
    eigen (+):
        Compute the eigenvalues and eigenvectors of selected symmetric matrices or matrix fields.
        If one selected image has 3 or 6 channels, it is regarded as a field of 2x2 or 3x3 symmetric matrices,
        whose eigen elements are computed at each point of the field.
    invert (+):
        Compute the inverse of the selected matrices.
    solve (+):
        [image]
        Solve linear system AX = B for selected B-matrices and specified A-matrix.
        If the system is under- or over-determined, the least square solution is returned.
    svd (+):
        Compute SVD decomposition of selected matrices.
    transpose:
        Transpose selected matrices.
    trisolve (+):
        [image]
        Solve tridiagonal system AX = B for selected B-vectors and specified tridiagonal A-matrix.
        Tridiagonal matrix must be stored as a 3 column vector, where 2nd column contains the
        diagonal coefficients, while 1st and 3rd columns contain the left and right coefficients.
 ** 3D Rendering:
    add3d (+):
        tx,_ty,_tz |
        [object3d] |
        (no arg)
        Shift selected 3D objects with specified displacement vector, or merge them with specified
        3D object, or merge all selected 3D objects together.
        (eq. to '+3d').

        Default values: 'ty=tz=0'.
    animate3d:
        _width>0,_height>0,_angle_dx,_angle_dy,_angle_dz,_zoom_factor>=0,_filename
        Animate selected 3D objects in a window.
        If argument 'filename' is provided, each frame of the animation is saved as a numbered filename.

        Default values: 'width=640', 'height=480', 'angle_dx=0', 'angle_dy=1', 'angle_dz=0',
          'zoom_factor=1' and 'filename=(undefined)'.
    apply_camera3d:
        pos_x,pos_y,pos_z,target_x,target_y,target_z,up_x,up_y,up_z
        Apply 3D camera matrix to selected 3D objects.

        Default values: 'target_x=0', 'target_y=0', 'target_z=0', 'up_x=0', 'up_y=-1' and 'up_z=0'.
    apply_matrix3d:
        a11,a12,a13,...,a31,a32,a33
        Apply specified 3D rotation matrix to selected 3D objects.
    array3d:
        size_x>=1,_size_y>=1,_size_z>=1,_offset_x[%],_offset_y[%],_offset_y[%]
        Duplicate a 3D object along the X,Y and Z axes.

        Default values: 'size_y=1', 'size_z=1' and 'offset_x=offset_y=offset_z=100%'.
    arrow3d:
        x0,y0,z0,x1,y1,z1,_radius[%]>=0,_head_length[%]>=0,_head_radius[%]>=0
        Input 3D arrow with specified starting and ending 3D points.

        Default values: 'radius=5%', 'head_length=25%' and 'head_radius=15%'.
    axes3d:
        _size_x,_size_y,_size_z,_font_size>0,_label_x,_label_y,_label_z,_is_origin={
          0=no | 1=yes }
        Input 3D axes with specified sizes along the x,y and z orientations.

        Default values: 'size_x=size_y=size_z=1', 'font_size=23', 'label_x=X', 'label_y=Y', 'label_z=Z'
          and 'is_origin=1'
    box3d:
        _size_x,_size_y,_size_z
        Input 3D box at (0,0,0), with specified geometry.

        Default values: 'size_x=1' and 'size_z=size_y=size_x'.
    center3d:
        Center selected 3D objects at (0,0,0).
        (eq. to 'c3d').
    circle3d:
        _x0,_y0,_z0,_radius>=0
        Input 3D circle at specified coordinates.

        Default values: 'x0=y0=z0=0' and 'radius=1'.
    circles3d:
        _radius>=0,_is_wireframe={ 0 | 1 }
        Convert specified 3D objects to sets of 3D circles with specified radius.

        Default values: 'radius=1' and 'is_wireframe=1'.
    color3d (+):
        R,_G,_B,_opacity
        Set color and opacity of selected 3D objects.
        (eq. to 'col3d').

        Default value: 'B=G=R' and 'opacity=(undefined)'.
    colorcube3d:
        Input 3D color cube.
    cone3d:
        _radius,_height,_nb_subdivisions>0
        Input 3D cone at (0,0,0), with specified geometry.

        Default value: 'radius=1','height=1' and 'nb_subdivisions=24'.
    cubes3d:
        _size>=0
        Convert specified 3D objects to sets of 3D cubes with specified size.

        Default value: 'size=1'.
    cup3d:
        _resolution>0
        Input 3D cup object.
    cylinder3d:
        _radius,_height,_nb_subdivisions>0
        Input 3D cylinder at (0,0,0), with specified geometry.

        Default value: 'radius=1','height=1' and 'nb_subdivisions=24'.
    delaunay3d:
        Generate 3D delaunay triangulations from selected images.
        One assumes that the selected input images are binary images containing the set of points to mesh.
        The output 3D object is a mesh composed of non-oriented triangles.
    distribution3d:
        Get 3D color distribution of selected images.
    div3d (+):
        factor |
        factor_x,factor_y,_factor_z
        Scale selected 3D objects isotropically or anisotropically, with the inverse of specified
        factors.
        (eq. to '/3d').

        Default value: 'factor_z=0'.
    double3d (+):
        _is_double_sided={ 0 | 1 }
        Enable/disable double-sided mode for 3D rendering.
        (eq. to 'db3d').

        Default value: 'is_double_sided=1'.
    elevation3d (+):
        z-factor |
        [elevation_map] |
        'formula' |
        (no arg)
        Build 3D elevation of selected images, with a specified elevation map.
        When invoked with (no arg) or 'z-factor', the elevation map is computed as the pointwise L2
          norm of the
        pixel values. Otherwise, the elevation map is taken from the specified image or formula.
    empty3d:
        Input empty 3D object.
    extrude3d:
        _depth>0,_resolution>0,_smoothness[%]>=0
        Generate extruded 3D object from selected binary XY-profiles.

        Default values: 'depth=16', 'resolution=1024' and 'smoothness=0.5%'.
    focale3d (+):
        focale
        Set 3D focale.
        (eq. to 'f3d').
        Set 'focale' to 0 to enable parallel projection (instead of perspective).
        Set negative 'focale' will disable 3D sprite zooming.

        Default value: 'focale=700'.
    gaussians3d:
        _size>0,_opacity
        Convert selected 3D objects into set of 3D gaussian-shaped sprites.
    gmic3d:
        Input a 3D G'MIC logo.
    gyroid3d:
        _resolution>0,_zoom
        Input 3D gyroid at (0,0,0), with specified resolution.

        Default values: 'resolution=32' and 'zoom=5'.
    histogram3d:
        Get 3D color histogram of selected images.
    image6cube3d:
        Generate 3D mapped cubes from 6-sets of selected images.
    imageblocks3d:
        _maximum_elevation,_smoothness[%]>=0
        Generate 3D blocks from selected images.
        Transparency of selected images is taken into account.

        Default values: 'maximum_elevation=10' and 'smoothness=0'.
    imagecube3d:
        Generate 3D mapped cubes from selected images.
    imageplane3d:
        Generate 3D mapped planes from selected images.
    imagepyramid3d:
        Generate 3D mapped pyramids from selected images.
    imagerubik3d:
        _xy_tiles>=1,0<=xy_shift<=100,0<=z_shift<=100
        Generate 3D mapped rubik's cubes from selected images.

        Default values: 'xy_tiles=3', 'xy_shift=5' and 'z_shift=5'.
    imagesphere3d:
        _resolution1>=3,_resolution2>=3
        Generate 3D mapped sphere from selected images.

        Default values: 'resolution1=32' and 'resolutions2=16'.
    isoline3d (+):
        isovalue[%] |
        'formula',value,_x0,_y0,_x1,_y1,_size_x>0[%],_size_y>0[%]
        Extract 3D isolines with specified value from selected images or from specified formula.

        Default values: 'x0=y0=-3', 'x1=y1=3' and 'size_x=size_y=256'.
    isosurface3d (+):
        isovalue[%] |
        'formula',value,_x0,_y0,_z0,_x1,_y1,_z1,_size_x>0[%],_size_y>0[%],_size_z>0[%]
        Extract 3D isosurfaces with specified value from selected images or from specified formula.

        Default values: 'x0=y0=z0=-3', 'x1=y1=z1=3' and 'size_x=size_y=size_z=32'.
    label3d:
        "text",font_height>=0,_opacity,_color1,...
        Generate 3D text label.

        Default values: 'font_height=13', 'opacity=1' and 'color=255,255,255'.
    label_points3d:
        _label_size>0,_opacity
        Add a numbered label to all vertices of selected 3D objects.

        Default values: 'label_size=13' and 'opacity=0.8'.
    lathe3d:
        _resolution>0,_smoothness[%]>=0,_max_angle>=0
        Generate 3D object from selected binary XY-profiles.

        Default values: 'resolution=128', 'smoothness=0.5%' and 'max_angle=361'.
    light3d (+):
        position_x,position_y,position_z |
        [texture] |
        (no arg)
        Set the light coordinates or the light texture for 3D rendering.
        (eq. to 'l3d').
        (no arg) resets the 3D light to default.
    line3d:
        x0,y0,z0,x1,y1,z1
        Input 3D line at specified coordinates.
    lissajous3d:
        resolution>1,a,A,b,B,c,C
        Input 3D lissajous curves (x(t)=sin(a*t+A*2*pi),y(t)=sin(b*t+B*2*pi),z(t)=sin(c*t+C*2*pi)).

        Default values: 'resolution=1024', 'a=2', 'A=0', 'b=1', 'B=0', 'c=0' and 'C=0'.
    mode3d (+):
        _mode
        Set static 3D rendering mode.
        (eq. to 'm3d').
        'mode' can be { -1=bounding-box | 0=dots | 1=wireframe | 2=flat | 3=flat-shaded |
          4=gouraud-shaded | 5=phong-shaded }.");
        Bounding-box mode ('mode==-1') is active only for the interactive 3D viewer.

        Default value: 'mode=4'.
    moded3d (+):
        _mode
        Set dynamic 3D rendering mode for interactive 3D viewer.
        (eq. to 'md3d').
        'mode' can be { -1=bounding-box | 0=dots | 1=wireframe | 2=flat | 3=flat-shaded |
          4=gouraud-shaded | 5=phong-shaded }.

        Default value: 'mode=-1'.
    mul3d (+):
        factor |
        factor_x,factor_y,_factor_z
        Scale selected 3D objects isotropically or anisotropically, with specified factors.
        (eq. to '*3d').

        Default value: 'factor_z=0'.
    normalize3d:
        Normalize selected 3D objects to unit size.
        (eq. to 'n3d').
    opacity3d (+):
        _opacity
        Set opacity of selected 3D objects.
        (eq. to 'o3d').

        Default value: 'opacity=1'.
    parametric3d:
        _x(a,b),_y(a,b),_z(a,b),_amin,_amax,_bmin,_bmax,_res_a>0,_res_b>0,_res_x>0,
          _res_y>0,_res_z>0,_smoothness>=0,_isovalue>=0
        Input 3D object from specified parametric surface (x(a,b),y(a,b),z(a,b)).

        Default values: 'x=(2+cos(b))*sin(a)', 'y=(2+cos(b))*cos(a)', 'c=sin(b)', 'amin=-pi',
          'amax='pi', 'bmin=-pi' and 'bmax='pi',
        'res_a=512', 'res_b=res_a', 'res_x=64', 'res_y=res_x', 'res_z=res_y', 'smoothness=2%' and
          'isovalue=10%'.
    pca_patch3d:
        _patch_size>0,_M>0,_N>0,_normalize_input={ 0 | 1 },_normalize_output={ 0 | 1 },
          _lambda_xy
        Get 3D patch-pca representation of selected images.
        The 3D patch-pca is estimated from M patches on the input image, and displayed as a cloud of N
          3D points.

        Default values: 'patch_size=7', 'M=1000', 'N=3000', 'normalize_input=1', 'normalize_output=0',
          and 'lambda_xy=0'.
    plane3d:
        _size_x,_size_y,_nb_subdivisions_x>0,_nb_subdisivions_y>0
        Input 3D plane at (0,0,0), with specified geometry.

        Default values: 'size_x=1', 'size_y=size_x' and 'nb_subdivisions_x=nb_subdivisions_y=24'.
    point3d:
        x0,y0,z0
        Input 3D point at specified coordinates.
    pointcloud3d:
        Convert selected planar or volumetric images to 3D point clouds.
    pose3d:
        p1,...,p12
        Apply 3D pose matrix to selected 3D objects.
    primitives3d:
        mode
        Convert primitives of selected 3D objects.
        (eq. to 'p3d').
        'mode' can be { 0=points | 1=outlines | 2=non-textured }.
    projections3d:
        _x[%],_y[%],_z[%],_is_bounding_box={ 0 | 1 }
        Generate 3D xy,xz,yz projection planes from specified volumetric images.
    pyramid3d:
        width,height
        Input 3D pyramid at (0,0,0), with specified geometry.
    quadrangle3d:
        x0,y0,z0,x1,y1,z1,x2,y2,z2,x3,y3,z3
        Input 3D quadrangle at specified coordinates.
    random3d:
        nb_points>=0
        Input random 3D point cloud in [0,1]^3.
    reverse3d (+):
        Reverse primitive orientations of selected 3D objects.
        (eq. to 'rv3d').
    rotate3d (+):
        u,v,w,angle
        Rotate selected 3D objects around specified axis with specified angle (in deg.).
        (eq. to 'r3d').
    rotation3d:
        u,v,w,angle
        Input 3x3 rotation matrix with specified axis and angle (in deg).
    sierpinski3d:
        _recursion_level>=0,_width,_height
        Input 3d Sierpinski pyramid.
    size3d:
        Return bounding box size of the last selected 3D object.
    skeleton3d:
        _metric,_frame_type={ 0=squares | 1=diamonds | 2=circles | 3=auto },
          _skeleton_opacity,_frame_opacity,_is_frame_wireframe={ 0 | 1 }
        Build 3D skeletal structure object from 2d binary shapes located in selected images.
        'metric' can be { 0=chebyshev | 1=manhattan | 2=euclidean }.

        Default values: 'metric=2', 'bones_type=3', 'skeleton_opacity=1' and 'frame_opacity=0.1'.
    snapshot3d:
        _size>0,_zoom>=0,_backgroundR,_backgroundG,_backgroundB,_backgroundA |
        [background_image],zoom>=0
        Take 2d snapshots of selected 3D objects.
        Set 'zoom' to 0 to disable object auto-scaling.

        Default values: 'size=512', 'zoom=1' and '[background_image]=(default)'.
    specl3d (+):
        value>=0
        Set lightness of 3D specular light.
        (eq. to 'sl3d').

        Default value: 'value=0.15'.
    specs3d (+):
        value>=0
        Set shininess of 3D specular light.
        (eq. to 'ss3d').

        Default value: 'value=0.8'.
    sphere3d (+):
        radius,_nb_recursions>=0
        Input 3D sphere at (0,0,0), with specified geometry.

        Default value: 'nb_recursions=3'.
    spherical3d:
        _nb_azimuth>=3,_nb_zenith>=3,_radius_function(phi,theta)
        Input 3D spherical object at (0,0,0), with specified geometry.

        Default values: 'nb_zenith=nb_azimut=64' and 'radius_function="abs(1+0.5*cos(3*phi)*sin(4*
          theta))"'.
    spline3d:
        x0[%],y0[%],z0[%],u0[%],v0[%],w0[%],x1[%],y1[%],z1[%],u1[%],v1[%],w1[%],
          _nb_vertices>=2
        Input 3D spline with specified geometry.

        Default values: 'nb_vertices=128'.
    split3d (+):
        _keep_shared_data={ 0 | 1 }
        Split selected 3D objects into 6 feature vectors :
        { header, sizes, vertices, primitives, colors, opacities }.
        (eq. to 's3d').
        To recreate the 3D object, append these 6 images along the y-axis.

        Default value: 'keep_shared_data=1'.
    sprite3d:
        Convert selected images as 3D sprites.
        Selected images with alpha channels are managed.
    sprites3d:
        [sprite],_sprite_has_alpha_channel={ 0 | 1 }
        Convert selected 3D objects as a sprite cloud.
        Set 'sprite_has_alpha_channel' to 1 to make the last channel of the selected sprite be a
          transparency mask.

        Default value: 'mask_has_alpha_channel=0'.
    star3d:
        _nb_branches>0,0<=_thickness<=1
        Input 3D star at (0,0,0), with specified geometry.

        Default values: 'nb_branches=5' and 'thickness=0.38'.
    streamline3d (+):
        x[%],y[%],z[%],_L>=0,_dl>0,_interpolation,_is_backward={ 0 | 1 },_is_oriented={ 0 | 1 } |
        'formula',x,y,z,_L>=0,_dl>0,_interpolation,_is_backward={ 0 | 1 },
          _is_oriented={ 0 | 1 }
        Extract 3D streamlines from selected vector fields or from specified formula.
        'interpolation' can be { 0=nearest integer | 1=1st-order | 2=2nd-order | 3=4th-order }.

        Default values: 'dl=0.1', 'interpolation=2', 'is_backward=0' and 'is_oriented=0'.
    sub3d (+):
        tx,_ty,_tz
        Shift selected 3D objects with the opposite of specified displacement vector.
        (eq. to '3d').

        Default values: 'ty=tz=0'.
    superformula3d:
        resolution>1,m>=1,n1,n2,n3
        Input 2D superformula curve as a 3D object.

        Default values: 'resolution=1024', 'm=8', 'n1=1', 'n2=5' and 'n3=8'.
    tensors3d:
        _radius_factor>=0,_shape={ 0=box | >=N=ellipsoid },_radius_min>=0
        Generate 3D tensor fields from selected images.
        when 'shape'>0, it gives the ellipsoid shape precision.

        Default values: 'radius_factor=1', 'shape=2' and 'radius_min=0.05'.
    text_pointcloud3d:
        _"text1",_"text2",_smoothness
        Input 3D text pointcloud from the two specified strings.

        Default values: 'text1="text1"', 'text2="text2"' and 'smoothness=1'.
    text3d:
        text,_font_height>0,_depth>0,_smoothness
        Input a 3D text object from specified text.

        Default values: 'font_height=53', 'depth=10' and 'smoothness=1.5'.
    texturize3d:
        [ind_texture],_[ind_coords]
        Texturize selected 3D objects with specified texture and coordinates.
        (eq. to 't3d').
        When '[ind_coords]' is omitted, default XY texture projection is performed.

        Default value: 'ind_coords=(undefined)'.
    torus3d:
        _radius1,_radius2,_nb_subdivisions1>2,_nb_subdivisions2>2
        Input 3D torus at (0,0,0), with specified geometry.

        Default values: 'radius1=1', 'radius2=0.3', 'nb_subdivisions1=24' and 'nb_subdivisions2=12'.
    triangle3d:
        x0,y0,z0,x1,y1,z1,x2,y2,z2
        Input 3D triangle at specified coordinates.
    volume3d:
        Transform selected 3D volumetric images as 3D parallelepipedic objects.
    weird3d:
        _resolution>0
        Input 3D weird object at (0,0,0), with specified resolution.

        Default value: 'resolution=32'.
 ** Control Flow:
    apply_parallel:
        "command"
        Apply specified command on each of the selected images, by parallelizing it for all image of the list.
        (eq. to 'ap').
    apply_parallel_channels:
        "command"
        Apply specified command on each of the selected images, by parallelizing it for all channel
        of the images independently.
        (eq. to 'apc').
    apply_parallel_overlap:
        "command",overlap[%],nb_threads={ 0=auto | 1 | 2 | 4 | 8 | 16 }
        Apply specified command on each of the selected images, by parallelizing it on 'nb_threads'
        overlapped sub-images.
        (eq. to 'apo').
        'nb_threads' must be a power of 2.

        Default values: 'overlap=0','nb_threads=0'.
    apply_tiles:
        "command",_tile_width[%]>0,_tile_height[%]>0,_tile_depth[%]>0,
          _overlap_width[%]>=0,_overlap_height[%]>=0,_overlap_depth[%]>=0,
          _boundary_conditions={ 0=dirichlet | 1=neumann | 2=periodic | 3=mirror }
        Apply specified command on each tile (neighborhood) of the selected images, eventually with
          overlapping tiles.
        (eq. to 'at').

        Default values: 'tile_width=tile_height=tile_depth=10%',
          'overlap_width=overlap_height=overlap_depth=0' and 'boundary_conditions=1'.
    apply_timeout:
        "command",_timeout={ 0=no timeout | >0=with specified timeout (in seconds) }
        Apply a command with a timeout.
    check (+):
        condition
        Evaluate specified condition and display an error message if evaluated to false.
        If 'expression' is not a math expression, it is regarded as a filename and checked if it exists.
    check3d (+):
        _is_full_check={ 0 | 1 }
        Check validity of selected 3D vector objects, and display an error message
        if one of the selected images is not a valid 3D vector object.
        Full 3D object check is slower but more precise.

        Default value: 'is_full_check=1'.
    check_display:
        Check if a display is available, and throw an error otherwise.
    continue (+):
        Go to end of current 'repeat...done', 'do...while' or 'local...endlocal' block.
    break (+):
        Break current 'repeat...done', 'do...while' or 'local...endlocal' block.
    do (+):
        Start a 'do...while' block.
    done (+):
        End a 'repeat/for...done' block, and go to associated 'repeat/for' position, if iterations remain.
    elif (+):
        condition
        Start a 'elif...[else]...fi' block if previous 'if' was not verified
        and test if specified condition is true, or if specified filename exists.
        'boolean' can be a float number standing for { 0=false | other=true }.
    else (+):
        Execute following commands if previous 'if' or 'elif' conditions failed.
    endif (+):
        End a 'if...[elif]...[else]...endif' block.
        (eq. to 'fi').
    endlocal (+):
        End a 'local...endlocal' block.
        (eq. to 'endl').
    error (+):
        message
        Print specified error message on the standard error (stderr) and exit interpreter, except
        if error is caught by a 'onfail' command.
        Command selection (if any) stands for displayed call stack subset instead of image indices.
    eval (+):
        expression
        Evaluate specified math expression.
        - If no command selection is specified, the expression is evaluated once and its result is set
          to status.
        - If command selection is specified, the evaluation is looped over selected images. Status is
          not modified.
        (in this latter case, 'eval' is similar to 'fill' without assigning the image values).
    exec (+):
        _is_verbose={ 0 | 1 },"command"
        Execute external command using a system call.
        The status value is then set to the error code returned by the system call.
        If 'is_verbose=1', the executed command is allowed to output on stdout/stderr.
        (eq. to 'x').

        Default value: 'is_verbose=1'.
    for (+):
        condition
        Start a 'for...done' block.
    if (+):
        condition
        Start a 'if...[elif]...[else]...fi' block and test if specified condition is true,
        or if specified filename exists.
        'boolean' can be a float number standing for { 0=false | other=true }.
    local (+):
        Start a 'local...[onfail]...endlocal' block, with selected images.
        (eq. to 'l').
    mutex (+):
        index,_action={ 0=unlock | 1=lock }
        Lock or unlock specified mutex for multi-threaded programming.
        A locked mutex can be unlocked only by the same thread. All mutexes are unlocked by default.
        'index' designates the mutex index, in [0,255].

        Default value: 'action=1'.
    noarg (+):
        Used in a custom command, 'noarg' tells the command that its argument list have not been used
        finally, and so they must be evaluated next in the G'MIC pipeline, just as if the custom
        command takes no arguments at all.
        Use this command to write a custom command which can decide if it takes arguments or not.
    onfail (+):
        Execute following commands when an error is encountered in the body of the 'local...endlocal' block.
        The status value is set with the corresponding error message.
    parallel (+):
        _wait_threads,"command1","command2",...
        Execute specified commands in parallel, each in a different thread.
        Parallel threads share the list of images.
        'wait_threads' can be { 0=when current environment ends | 1=immediately }.

        Default value: 'wait_threads=1'.
    progress (+):
        0<=value<=100 |
        -1
        Set the progress index of the current processing pipeline.
        This command is useful only when G'MIC is used by an embedding application.
    quit (+):
        Quit G'MIC interpreter.
        (eq. to 'q').
    repeat (+):
        nb_iterations,_variable_name
        Start iterations of a 'repeat...done' block.
    return (+):
        Return from current custom command.
    rprogress:
        0<=value<=100 | -1 | "command",0<=value_min<=100,0<=value_max<=100
        Set the progress index of the current processing pipeline (relatively to
        previously defined progress bounds), or call the specified command with
        specified progress bounds.
    run:
        "G'MIC pipeline"
        Run specified G'MIC pipeline.
        This is only useful when used from a shell, e.g. to avoid shell substitutions to happen in argument.
    skip (+):
        item
        Do nothing but skip specified item.
    status (+):
        status_string
        Set the current status. Used to define a returning value from a function.
        (eq. to 'u').
    while (+):
        condition
        End a 'do...while' block and go back to associated 'do'
        if specified condition is true or if specified filename exists.
        'boolean' can be a float number standing for { 0=false | other=true }.
 ** Arrays, Tiles and Frames:
    array:
        M>0,_N>0,_expand_type={ 0=min | 1=max | 2=all }
        Create MxN array from selected images.

        Default values: 'N=M' and 'expand_type=0'.
    array_fade:
        M>0,_N>0,0<=_fade_start<=100,0<=_fade_end<=100,_expand_type={0=min | 1=max | 2=all}
        Create MxN array from selected images.

        Default values: 'N=M', 'fade_start=60', 'fade_end=90' and 'expand_type=1'.
    array_mirror:
        N>=0,_dir={ 0=x | 1=y | 2=xy | 3=tri-xy },_expand_type={ 0 | 1 }
        Create 2^Nx2^N array from selected images.

        Default values: 'dir=2' and 'expand_type=0'.
    array_random:
        Ms>0,_Ns>0,_Md>0,_Nd>0
        Create MdxNd array of tiles from selected MsxNs source arrays.

        Default values: 'Ns=Ms', 'Md=Ms' and 'Nd=Ns'.
    frame_blur:
        _sharpness>0,_size>=0,_smoothness,_shading,_blur
        Draw RGBA-colored round frame in selected images.

        Default values: 'sharpness=10', 'size=30', 'smoothness=0', 'shading=1' and 'blur=3%'.
    frame_cube:
        _depth>=0,_centering_x,_centering_y,_left_side={0=normal | 1=mirror-x |
          2=mirror-y | 3=mirror-xy},_right_side,_lower_side,_upper_side
        Insert 3D frames in selected images.

        Default values: 'depth=1', 'centering_x=centering_y=0' and 'left_side=right_side,
          lower_side=upper_side=0'.
    frame_fuzzy:
        size_x[%]>=0,_size_y[%]>=0,_fuzzyness>=0,_smoothness[%]>=0,_R,_G,_B,_A
        Draw RGBA-colored fuzzy frame in selected images.

        Default values: 'size_y=size_x', 'fuzzyness=5', 'smoothness=1' and 'R=G=B=A=255'.
    frame_painting:
        _size[%]>=0,0<=_contrast<=1,_profile_smoothness[%]>=0,_R,_G,_B,
          _vignette_size[%]>=0,_vignette_contrast>=0,_defects_contrast>=0,
          0<=_defects_density<=100,_defects_size>=0,_defects_smoothness[%]>=0,
          _serial_number
        Add a painting frame to selected images.

        Default values: 'size=10%', 'contrast=0.4', 'profile_smoothness=6%', 'R=225', 'G=200', 'B=120',
          'vignette_size=2%', 'vignette_contrast=400', 'defects_contrast=50', 'defects_density=10',
          'defects_size=1', 'defects_smoothness=0.5%' and 'serial_number=123456789'.
    frame_pattern:
        M>=3,_constrain_size={ 0 | 1 } |
        M>=3,_[frame_image],_constrain_size={ 0 | 1 }
        Insert selected pattern frame in selected images.

        Default values: 'pattern=0' and 'constrain_size=0'.
    frame_round:
        _sharpness>0,_size>=0,_smoothness,_shading,_R,_G,_B,_A
        Draw RGBA-colored round frame in selected images.

        Default values: 'sharpness=10', 'size=10', 'smoothness=0', 'shading=0' and 'R=G=B=A=255'.
    frame_seamless:
        frame_size>=0,_patch_size>0,_blend_size>=0,_frame_direction={ 0=inner (preserve
          image size) | 1=outer }
        Insert frame in selected images, so that tiling the resulting image makes less visible seams.

        Default values: 'patch_size=7', 'blend_size=5' and 'frame_direction=1'.
    frame_x:
        size_x[%],_col1,...,_colN
        Insert colored frame along the x-axis in selected images.

        Default values: 'col1=col2=col3=255' and 'col4=255'.
    frame_xy:
        size_x[%],_size_y[%],_col1,...,_colN
        Insert colored frame along the x-axis in selected images.

        Default values: 'size_y=size_x', 'col1=col2=col3=255' and 'col4=255'.
        (eq. to 'frame').
    frame_xyz:
        size_x[%],_size_y[%],_size_z[%]_col1,...,_colN
        Insert colored frame along the x-axis in selected images.

        Default values: 'size_y=size_x=size_z', 'col1=col2=col3=255' and 'col4=255'.
    frame_y:
        size_y[%],_col1,...,_colN
        Insert colored frame along the y-axis in selected images.

        Default values: 'col1=col2=col3=255' and 'col4=255'.
    img2ascii:
        _charset,_analysis_scale>0,_analysis_smoothness[%]>=0,_synthesis_scale>0,
          _output_ascii_filename
        Render selected images as binary ascii art.
        This command returns the corresponding the list of widths and heights (expressed as a number of
          characters)
        for each selected image.

        Default values: 'charset=[ascii charset]', 'analysis_scale=16', 'analysis_smoothness=20%',
          'synthesis_scale=16' and '_output_ascii_filename=[undefined]'.
    imagegrid:
        M>0,_N>0
        Create MxN image grid from selected images.

        Default value: 'N=M'.
    imagegrid_hexagonal:
        _resolution>0,0<=_outline<=1
        Create hexagonal grids from selected images.

        Default values: 'resolution=32', 'outline=0.1' and 'is_antialiased=1'.
    imagegrid_triangular:
        pattern_width>=1,_pattern_height>=1,_pattern_type,0<=_outline_opacity<=1,
          _outline_color1,...
        Create triangular grids from selected images.
        'pattern type' can be { 0=horizontal | 1=vertical | 2=crossed | 3=cube | 4=decreasing |
          5=increasing }.

        Default values: 'pattern_width=24', 'pattern_height=pattern_width', 'pattern_type=0',
          'outline_opacity=0.1' and 'outline_color1=0'.
    linearize_tiles:
        M>0,_N>0
        Linearize MxN tiles on selected images.

        Default value: 'N=M'.
    map_sprites:
        _nb_sprites>=1,_allow_rotation={ 0=none | 1=90 deg. | 2=180 deg. }
        Map set of sprites (defined as the 'nb_sprites' latest images of the selection) to other
          selected images,
        according to the luminosity of their pixel values.
    pack:
        is_ratio_constraint={ 0 | 1 },_sort_criterion
        Pack selected images into a single image.
        The returned status contains the list of new (x,y) offsets for each input image.
        Parameter 'is_ratio_constraint' tells if the resulting image must tend to a square image.

        Default values: 'is_ratio_constraint=0' and 'sort_criterion=max(w,h)'.
    puzzle:
        _width>0,_height>0,_M>=1,_N>=1,_curvature,_centering,_connectors_variability,
          _resolution>=1
        Input puzzle binary mask with specified size and geometry.

        Default values: 'width=height=512', 'M=N=5', 'curvature=0.5', 'centering=0.5',
          'connectors_variability=0.5' and 'resolution=64'.
    quadratize_tiles:
        M>0,_N>0
        Quadratize MxN tiles on selected images.

        Default value: 'N=M'.
    rotate_tiles:
        angle,_M>0,N>0
        Apply MxN tiled-rotation effect on selected images.

        Default values: 'M=8' and 'N=M'.
    shift_tiles:
        M>0,_N>0,_amplitude
        Apply MxN tiled-shift effect on selected images.

        Default values: 'N=M' and 'amplitude=20'.
    taquin:
        M>0,_N>0,_remove_tile={ 0=none | 1=first | 2=last | 3=random },_relief,
          _border_thickness[%],_border_outline[%],_outline_color
        Create MxN taquin puzzle from selected images.

        Default value: 'N=M', 'relief=50', 'border_thickness=5', 'border_outline=0' and 'remove_tile=0'.
    tunnel:
        _level>=0,_factor>0,_centering_x,_centering_y,_opacity,_angle
        Apply tunnel effect on selected images.

        Default values: 'level=9', 'factor=80%', 'centering_x=centering_y=0.5', 'opacity=1' and 'angle=0'
 ** Artistic:
    boxfitting:
        _min_box_size>=1,_max_box_size>=0,_initial_density>=0,_nb_attempts>=1
        Apply box fitting effect on selected images, as displayed the web page:
        [http://www.complexification.net/gallery/machines/boxFittingImg/]

        Default values: 'min_box_size=1', 'max_box_size=0', 'initial_density=0.1' and 'nb_attempts=3'.
    brushify:
        [brush],_brush_nb_sizes>=1,0<=_brush_min_size_factor<=1,
          _brush_nb_orientations>=1,_brush_light_type,0<=_brush_light_strength<=1,
          _brush_opacity,_painting_density[%]>=0,0<=_painting_contours_coherence<=1,
          0<=_painting_orientation_coherence<=1,_painting_coherence_alpha[%]>=0,
          _painting_coherence_sigma[%]>=0,_painting_primary_angle,
          0<=_painting_angle_dispersion<=1
        Apply specified brush to create painterly versions of specified images.
        'brush_light_type' can be { 0=none | 1=flat | 2=darken | 3=lighten | 4=full }.

        Default values: 'brush_nb_sizes=3', 'brush_min_size_factor=0.66', 'brush_nb_orientations=12',
          'brush_light_type=0', 'brush_light_strength=0.25', 'brush_opacity=0.8', 'painting_density=20%',
          'painting_contours_coherence=0.9', 'painting_orientation_coherence=0.9',
          'painting_coherence_alpha=1', 'painting_coherence_sigma=1', 'painting_primary_angle=0',
          'painting_angle_dispersion=0.2'
    cartoon:
        _smoothness,_sharpening,_threshold>=0,_thickness>=0,_color>=0,quantization>0
        Apply cartoon effect on selected images.

        Default values: 'smoothness=3', 'sharpening=150', 'threshold=20', 'thickness=0.25', 'color=1.5'
          and 'quantization=8'.
    color_ellipses:
        _count>0,_radius>=0,_opacity>=0
        Add random color ellipses to selected images.

        Default values: 'count=400', 'radius=5' and 'opacity=0.1'.
    cubism:
        _density>=0,0<=_thickness<=50,_max_angle,_opacity,_smoothness>=0
        Apply cubism effect on selected images.

        Default values: 'density=50', 'thickness=10', 'max_angle=75', 'opacity=0.7' and 'smoothness=0'.
    draw_whirl:
        _amplitude>=0
        Apply whirl drawing effect on selected images.

        Default value: 'amplitude=100'.
    drawing:
        _amplitude>=0
        Apply drawing effect on selected images.

        Default value: 'amplitude=200'.
    drop_shadow:
        _offset_x[%],_offset_y[%],_smoothness[%]>=0,0<=_curvature<=1,_expand_size={ 0 | 1 }
        Drop shadow behind selected images.

        Default values: 'offset_x=20', 'offset_y=offset_x', 'smoothness=5', 'curvature=0' and
          'expand_size=1'.
    ellipsionism:
        _R>0[%],_r>0[%],_smoothness>=0[%],_opacity,_outline>0,_density>0
        Apply ellipsionism filter to selected images.

        Default values: 'R=10', 'r=3', 'smoothness=1%', 'opacity=0.7', 'outline=8' and 'density=0.6'.
    fire_edges:
        _edges>=0,0<=_attenuation<=1,_smoothness>=0,_threshold>=0,_nb_frames>0,
          _starting_frame>=0,frame_skip>=0
        Generate fire effect from edges of selected images.

        Default values: 'edges=0.7', 'attenuation=0.25', 'smoothness=0.5', 'threshold=25',
          'nb_frames=1', 'starting_frame=20' and 'frame_skip=0'.
    fractalize:
        0<=detail_level<=1
        Randomly fractalize selected images.

        Default value: 'detail_level=0.8'
    glow:
        _amplitude>=0
        Add soft glow on selected images.

        Default value: 'amplitude=1%'.
    halftone:
        nb_levels>=2,_size_dark>=2,_size_bright>=2,_shape={ 0=square | 1=diamond |
          2=circle | 3=inv-square | 4=inv-diamond | 5=inv-circle },_smoothness[%]>=0
        Apply halftone dithering to selected images.

        Default values: 'nb_levels=5', 'size_dark=8', 'size_bright=8', 'shape=5' and 'smoothnesss=0'.
    hardsketchbw:
        _amplitude>=0,_density>=0,_opacity,0<=_edge_threshold<=100,_is_fast={ 0 | 1 }
        Apply hard B&W sketch effect on selected images.

        Default values: 'amplitude=1000', 'sampling=3', 'opacity=0.1', 'edge_threshold=20' and
          'is_fast=0'.
    hearts:
        _density>=0
        Apply heart effect on selected images.

        Default value: 'density=10'.
    houghsketchbw:
        _density>=0,_radius>0,0<=_threshold<=100,0<=_opacity<=1,_votesize[%]>0
        Apply hough B&W sketch effect on selected images.

        Default values: 'density=8', 'radius=5', 'threshold=80', 'opacity=0.1' and 'votesize=100%'.
    lightrays:
        100<=_density<=0,_center_x[%],_center_y[%],_ray_length>=0,_ray_attenuation>=0
        Generate ray lights from the edges of selected images.
        Defaults values : 'density=50%', 'center_x=50%', 'center_y=50%', 'ray_length=0.9' and
          'ray_attenuation=0.5'.
    light_relief:
        _ambient_light,_specular_lightness,_specular_size,_light_smoothness,_darkness,
          _xl,_yl,_zl,_zscale,_opacity_is_heightmap={ 0 | 1 }
        Apply relief light to selected images.
        Default values(s) : 'ambient_light=0.3', 'specular_lightness=0.5', 'specular_size=0.2',
          'darkness=0', 'xl=0.2', 'yl=zl=0.5',
        'zscale=1', 'opacity=1' and 'opacity_is_heightmap=0'.
    linify:
        0<=_density<=100,_spreading>=0,_resolution[%]>0,_line_opacity>=0,
          _line_precision>0,_mode={ 0=subtractive | 1=additive }
        Apply linify effect on selected images.
        The algorithm is inspired from the one described on the webpage 'http://linify.me/about'.

        Default values: 'density=50', 'spreading=2', 'resolution=40%', 'line_opacity=10',
          'line_precision=24' and 'mode=0'.
    mosaic:
        0<=_density<=100
        Create random mosaic from selected images.

        Default values: 'density=30'.
    old_photo:
        Apply old photo effect on selected images.
    pencilbw:
        _size>=0,_amplitude>=0
        Apply B&W pencil effect on selected images.

        Default values: 'size=0.3' and 'amplitude=60'.
    pixelsort:
        _ordering={ + | - },_axis={ x | y | z | xy | yx },_[sorting_criterion],_[mask]
        Apply a 'pixel sorting' algorithm on selected images, as described in the page :
        http://satyarth.me/articles/pixel-sorting/

        Default values: 'ordering=+', 'axis=x' and 'sorting_criterion=mask=(undefined)'.
    polaroid:
        _size1>=0,_size2>=0
        Create polaroid effect in selected images.

        Default values: 'size1=10' and 'size2=20'.
    polygonize:
        _warp_amplitude>=0,_smoothness[%]>=0,_min_area[%]>=0,_resolution_x[%]>0,
          _resolution_y[%]>0
        Apply polygon effect on selected images.

        Default values: 'warp_amplitude=300', 'smoothness=2%', 'min_area=0.1%',
          'resolution_x=resolution_y=10%'.
    poster_edges:
        0<=_edge_threshold<=100,0<=_edge_shade<=100,_edge_thickness>=0,
          _edge_antialiasing>=0,0<=_posterization_level<=15,_posterization_antialiasing>=0
        Apply poster edges effect on selected images.

        Default values: 'edge_threshold=40', 'edge_shade=5', 'edge_thickness=0.5',
          'edge_antialiasing=10', 'posterization_level=12' and 'posterization_antialiasing=0'.
    poster_hope:
        _smoothness>=0
        Apply Hope stencil poster effect on selected images.

        Default value: 'smoothness=3'.
    rodilius:
        0<=_amplitude<=100,_0<=thickness<=100,_sharpness>=0,_nb_orientations>0,_offset,
          _color_mode={ 0=darker | 1=brighter }
        Apply rodilius (fractalius-like) filter on selected images.

        Default values: 'amplitude=10', 'thickness=10', 'sharpness=400', 'nb_orientations=7',
          'offset=0' and 'color_mode=1'.
    sketchbw:
        _nb_angles>0,_start_angle,_angle_range>=0,_length>=0,_threshold>=0,_opacity,
          _bgfactor>=0,_density>0,_sharpness>=0,_anisotropy>=0,_smoothness>=0,
          _coherence>=0,_is_boost={ 0 | 1 },_is_curved={ 0 | 1 }
        Apply sketch effect to selected images.

        Default values: 'nb_angles=2', 'start_angle=45', 'angle_range=180', 'length=30', 'threshold=3',
          'opacity=0.03', 'bgfactor=0', 'density=0.6', 'sharpness=0.1', 'anisotropy=0.6', 'smoothness=0.
          25', 'coherence=1', 'is_boost=0' and 'is_curved=1'.
    sponge:
        _size>0
        Apply sponge effect on selected images.

        Default value: 'size=13'.
    stained_glass:
        _edges[%]>=0, shading>=0, is_thin_separators={ 0 | 1 }
        Generate stained glass from selected images.

        Default values: 'edges=40%', 'shading=0.2' and 'is_precise=0'.
    stars:
        _density[%]>=0,_depth>=0,_size>0,_nb_branches>=1,0<=_thickness<=1,
          _smoothness[%]>=0,_R,_G,_B,_opacity
        Add random stars to selected images.

        Default values: 'density=10%', 'depth=1', 'size=32', 'nb_branches=5', 'thickness=0.38',
          'smoothness=0.5', 'R=G=B=200' and 'opacity=1'.
    stencil:
        _radius[%]>=0,_smoothness>=0,_iterations>=0
        Apply stencil filter on selected images.

        Default values: 'radius=3', 'smoothness=1' and 'iterations=8'.
    stencilbw:
        _edges>=0,_smoothness>=0
        Apply B&W stencil effect on selected images.

        Default values: 'edges=15' and 'smoothness=10'.
    stylize:
        [style_image],_fidelity_finest,_fidelity_coarsest,
          _fidelity_smoothness_finest>=0,_fidelity_smoothnes_coarsest>=0,
          0<=_fidelity_chroma<=1,_init_type,_init_resolution>=0,init_max_gradient>=0,
          _patchsize_analysis>0,_patchsize_synthesis>0,_patchsize_synthesis_final>0,
          _nb_matches_finest>=0,_nb_matches_coarsest>=0,_penalize_repetitions>=0,
          _matching_precision>=0,_scale_factor>1,_skip_finest_scales>=0,
          "image_matching_command"
        Transfer colors and textures from specified style image to selected images, using a multi-scale
          patch-mathing algorithm.
        If instant display window[0] is opened, the steps of the image synthesis are displayed on it.
        'init_type' can be { 0=best-match | 1=identity | 2=randomized}.
    tetris:
        _scale>0
        Apply tetris effect on selected images.

        Default value: 'scale=10'.
    warhol:
        _M>0,_N>0,_smoothness>=0,_color>=0
        Create MxN Andy Warhol-like artwork from selected images.

        Default values: 'M=3', 'N=M', 'smoothness=2' and 'color=20'.
    weave:
        _density>=0,0<=_thickness<=100,0<=_shadow<=100,_shading>=0,_fibers_amplitude>=0,
          _fibers_smoothness>=0,_angle,-1<=_x_curvature<=1,-1<=_y_curvature<=1
        Apply weave effect to the selected images.
        'angle' can be { 0=0 deg. | 1=22.5 deg. | 2=45 deg. | 3=67.5 deg. }.

        Default values: 'density=6', 'thickness=65', 'shadow=40', 'shading=0.5', 'fibers_amplitude=0', _
    whirls:
        _texture>=0,_smoothness>=0,_darkness>=0,_lightness>=0
        Add random whirl texture to selected images.

        Default values: 'texture=3', 'smoothness=6', 'darkness=0.5' and 'lightness=1.8'.
 ** Warpings:
    deform:
        _amplitude>=0,_interpolation
        Apply random smooth deformation on selected images.
        'interpolation' can be { 0=none | 1=linear | 2=bicubic }.

        Default value: 'amplitude=10'.
    euclidean2polar:
        _center_x[%],_center_y[%],_stretch_factor>0,_boundary_conditions={ 0=dirichlet |
           1=neumann | 2=periodic | 3=mirror }
        Apply euclidean to polar transform on selected images.

        Default values: 'center_x=center_y=50%', 'stretch_factor=1' and 'boundary_conditions=1'.
    equirectangular2nadirzenith:
        Transform selected equirectangular images to nadir/zenith rectilinear projections.
    fisheye:
        _center_x,_center_y,0<=_radius<=100,_amplitude>=0
        Apply fish-eye deformation on selected images.

        Default values: 'x=y=50', 'radius=50' and 'amplitude=1.2'.
    flower:
        _amplitude,_frequency,_offset_r[%],_angle,_center_x[%],_center_y[%],
          _boundary_conditions={ 0=dirichlet | 1=neumann | 2=periodic | 3=mirror}
        Apply flower deformation on selected images.

        Default values: 'amplitude=30', 'frequency=6', 'offset_r=0', 'angle=0', 'center_x=center_y=50%'
          and 'boundary_conditions=3'.
    kaleidoscope:
        _center_x[%],_center_y[%],_radius,_angle,_boundary_conditions={ 0=dirichlet |
          1=neumann | 2=periodic | 3=mirror }
        Create kaleidoscope effect from selected images.

        Default values: 'center_x=center_y=50%', 'radius=100', 'angle=30' and 'boundary_conditions=3'.
    map_sphere:
        _width>0,_height>0,_radius,_dilation>0,_fading>=0,_fading_power>=0
        Map selected images on a sphere.

        Default values: 'width=height=512', 'radius=100', 'dilation=0.5', 'fading=0' and
          'fading_power=0.5'.
    nadirzenith2equirectangular:
        Transform selected nadir/zenith rectilinear projections to equirectangular images.
    polar2euclidean:
        _center_x[%],_center_y[%],_stretch_factor>0,_boundary_conditions={ 0=dirichlet |
           1=neumann | 2=periodic | 3=mirror }
        Apply euclidean to polar transform on selected images.

        Default values: 'center_x=center_y=50%', 'stretch_factor=1' and 'boundary_conditions=1'.
    raindrops:
        _amplitude,_density>=0,_wavelength>=0,_merging_steps>=0
        Apply raindrops deformation on selected images.

        Default values: 'amplitude=80','density=0.1', 'wavelength=1' and 'merging_steps=0'.
    ripple:
        _amplitude,_bandwidth,_shape={ 0=bloc | 1=triangle | 2=sine | 3=sine+ |
          4=random },_angle,_offset
        Apply ripple deformation on selected images.

        Default values: 'amplitude=10', 'bandwidth=10', 'shape=2', 'angle=0' and 'offset=0'.
    rotoidoscope:
        _center_x[%],_center_y[%],_tiles>0,_smoothness[%]>=0,_boundary_conditions={
          0=dirichlet | 1=neumann | 2=periodic | 3=mirror }
        Create rotational kaleidoscope effect from selected images.

        Default values: 'center_x=center_y=50%', 'tiles=10', 'smoothness=1' and 'boundary_conditions=3'.
    spherize:
        _radius[%]>=0,_strength,_smoothness[%]>=0,_center_x[%],_center_y[%],_ratio_x/
          y>0,_angle,_interpolation
        Apply spherize effect on selected images.

        Default values: 'radius=50%', 'strength=1', 'smoothness=0', 'center_x=center_y=50%', 'ratio_x/
          y=1', 'angle=0' and 'interpolation=1'.
    symmetrize:
        _x[%],_y[%],_angle,_boundary_conditions={ 0=dirichlet | 1=neumann | 2=periodic |
           3=mirror },_is_antisymmetry={ 0 | 1 },_swap_sides={ 0 | 1 }
        Symmetrize selected images regarding specified axis.

        Default values: 'x=y=50%', 'angle=90', 'boundary_conditions=3', 'is_antisymmetry=0' and
          'swap_sides=0'.
    transform_polar:
        "expr_radius",_"expr_angle",_center_x[%],_center_y[%],_boundary_conditions={
          0=dirichlet | 1=neumann }
        Apply user-defined transform on polar representation of selected images.

        Default values: 'expr_radius=R-r', 'expr_rangle=a', 'center_x=center_y=50%' and
          'boundary_conditions=1'.
    twirl:
        _amplitude,_center_x[%],_center_y[%],_boundary_conditions={ 0=dirichlet |
          1=neumann | 2=periodic | 3=mirror }
        Apply twirl deformation on selected images.

        Default values: 'amplitude=1', 'center_x=center_y=50%' and 'boundary_conditions=3'.
    warp_perspective:
        _x-angle,_y-angle,_zoom>0,_x-center,_y-center,_boundary_conditions={
          0=dirichlet | 1=neumann | 2=periodic | 3=mirror }
        Warp selected images with perspective deformation.

        Default values: 'x-angle=1.5', 'y-angle=0', 'zoom=1', 'x-center=y-center=50' and
          'boundary_conditions=2'.
    water:
        _amplitude,_smoothness>=0,_angle
        Apply water deformation on selected images.

        Default values: 'amplitude=30', 'smoothness=1.5' and 'angle=45'.
    wave:
        _amplitude>=0,_frequency>=0,_center_x,_center_y
        Apply wave deformation on selected images.

        Default values: 'amplitude=4', 'frequency=0.4' and 'center_x=center_y=50'.
    wind:
        _amplitude>=0,_angle,0<=_attenuation<=1,_threshold
        Apply wind effect on selected images.

        Default values: 'amplitude=20', 'angle=0', 'attenuation=0.7' and 'threshold=20'.
    zoom:
        _factor,_cx,_cy,_cz,_boundary_conditions={ 0=dirichlet | 1=neumann | 2=periodic
          | 3=mirror }
        Apply zoom factor to selected images.

        Default values: 'factor=1', 'cx=cy=cz=0.5' and 'boundary_conditions=0'.
 ** Degradations:
    cracks:
        0<=_density<=100,_is_relief={ 0 | 1 },_opacity,_color1,...
        Draw random cracks on selected images with specified color.

        Default values: 'density=25', 'is_relief=0', 'opacity=1' and 'color1=0'.
    light_patch:
        _density>0,_darkness>=0,_lightness>=0
        Add light patches to selected images.

        Default values: 'density=10', 'darkness=0.9' and 'lightness=1.7'.
    noise_hurl:
        _amplitude>=0
        Add hurl noise to selected images.

        Default value: 'amplitude=10'.
    pixelize:
        _scale_x>0,_scale_y>0,_scale_z>0
        Pixelize selected images with specified scales.

        Default values: 'scale_x=20' and 'scale_y=scale_z=scale_x'.
    scanlines:
        _amplitude,_bandwidth,_shape={ 0=bloc | 1=triangle | 2=sine | 3=sine+ |
          4=random },_angle,_offset
        Apply ripple deformation on selected images.

        Default values: 'amplitude=60', 'bandwidth=2', 'shape=0', 'angle=0' and 'offset=0'.
    shade_stripes:
        _frequency>=0,_direction={ 0=horizontal | 1=vertical },_darkness>=0,
          _lightness>=0
        Add shade stripes to selected images.

        Default values: 'frequency=5', 'direction=1', 'darkness=0.8' and 'lightness=2'.
    shadow_patch:
        _opacity>=0
        Add shadow patches to selected images.

        Default value: 'opacity=0.7'.
    spread:
        _dx>=0,_dy>=0,_dz>=0
        Spread pixel values of selected images randomly along x,y and z.

        Default values: 'dx=3', 'dy=dx' and 'dz=0'.
    stripes_y:
        _frequency>=0
        Add vertical stripes to selected images.

        Default value: 'frequency=10'.
    texturize_canvas:
        _amplitude>=0,_fibrousness>=0,_emboss_level>=0
        Add paint canvas texture to selected images.

        Default values: 'amplitude=20', 'fibrousness=3' and 'emboss_level=0.6'.
    texturize_paper:
        Add paper texture to selected images.
    vignette:
        _strength>=0,0<=_radius_min<=100,0<=_radius_max<=100
        Add vignette effect to selected images.

        Default values: 'strength=100', 'radius_min=70' and 'radius_max=90'.
    watermark_visible:
        _text,0<_opacity<1,_size>0,_angle,_mode={ 0=remove | 1=add },_smoothness>=0
        Add or remove a visible watermark on selected images (value range must be [0,255]).

        Default values: 'text=(c) G'MIC', 'opacity=0.3', 'size=53', 'angle=25', 'mode=1' and
          'smoothness=0'.
 ** Blending and Fading:
    blend:
        [layer],blending_mode,_opacity[%],_selection_is={ 0=base-layers | 1=top-layers } |
        blending_mode,_opacity[%]
        Blend selected G,GA,RGB or RGBA images by specified layer or blend all selected images together,
        using specified blending mode.
        'blending_mode' can be { add | alpha | and | average | blue | burn | darken | difference |
        divide | dodge | edges | exclusion | freeze | grainextract | grainmerge | green | hardlight |
        hardmix | hue | interpolation | lighten | lightness | linearburn | linearlight | luminance |
        multiply | negation | or | overlay | pinlight | red | reflect | saturation | seamless |
          seamless_mixed |
        screen | shapeareamax | shapeareamax0 | shapeareamin | shapeareamin0 | shapeaverage |
          shapeaverage0 |
        shapemedian | shapemedian0 | shapemin | shapemin0 | shapemax | shapemax0 | softburn | softdodge |
        softlight | stamp | subtract | value | vividlight | xor }.
        'opacity' should be in '[0,1]', or '[0,100]' if expressed with a '%'.

        Default values: 'blending_mode=alpha', 'opacity=1' and 'selection_is=0'.
    blend_edges:
        smoothness[%]>=0
        Blend selected images togethers using 'edges' mode.
    blend_fade:
        [fading_shape]
        Blend selected images together using specified fading shape.
    blend_median:
        Blend selected images together using 'median' mode.
    blend_seamless:
        _is_mixed_mode={ 0 | 1 },_inner_fading[%]>=0,_outer_fading[%]>=0
        Blend selected images using a seamless blending mode (Poisson-based).

        Default values: 'is_mixed=0', 'inner_fading=0' and 'outer_fading=100%'.
    fade_diamond:
        0<=_start<=100,0<=_end<=100
        Create diamond fading from selected images.

        Default values: 'start=80' and 'end=90'.
    fade_linear:
        _angle,0<=_start<=100,0<=_end<=100
        Create linear fading from selected images.

        Default values: 'angle=45', 'start=30' and 'end=70'.
    fade_radial:
        0<=_start<=100,0<=_end<=100
        Create radial fading from selected images.

        Default values: 'start=30' and 'end=70'.
    fade_x:
        0<=_start<=100,0<=_end<=100
        Create horizontal fading from selected images.

        Default values: 'start=30' and 'end=70'.
    fade_y:
        0<=_start<=100,0<=_end<=100
        Create vertical fading from selected images.

        Default values: 'start=30' and 'end=70'.
    fade_z:
        0<=_start<=100,0<=_end<=100
        Create transversal fading from selected images.

        Default values: 'start=30' and 'end=70'.
    sub_alpha:
        [base_image],_opacity_gain>=1
        Compute the minimal alpha-channel difference (opposite of alpha blending) between the selected images
        and the specified base image.
        The alpha difference A-B is defined as the image having minimal opacity, such that
          alpha_blend(B,A-B) = A.

        Default value: 'opacity_gain=1'.
 ** Image Sequences and Videos:
    animate:
        filter_name,"param1_start,...,paramN_start","param1_end,...,paramN_end",
          nb_frames>=0,_output_frames={ 0 | 1 },_output_filename |
        delay>0,_back and forth={ 0 | 1 }
        Animate filter from starting parameters to ending parameters or animate selected images
        in a display window.

        Default value: 'delay=30'.
    apply_camera:
        _"command",_camera_index>=0,_skip_frames>=0,_output_filename
        Apply specified command on live camera stream, and display it on display window [0].

        Default values: 'command=""', 'camera_index=0' (default camera), 'skip_frames=0' and
          'output_filename=""'.
    apply_files:
        "filename_pattern",_"command",_first_frame>=0,_last_frame={ >=0 | -1=last },
          _frame_step>=1,_output_filename
        Apply a G'MIC command on specified input image files, in a streamed way.
        If a display window is opened, rendered frames are displayed in it during processing.
        The output filename may have extension '.avi' (saved as a video), or any other usual image file
        extension (saved as a sequence of images).

        Default values: 'command=(undefined)', 'first_frame=0', 'last_frame=-1', 'frame_step=1' and
          'output_filename=(undefined)'.
    apply_video:
        video_filename,_"command",_first_frame>=0,_last_frame={ >=0 | -1=last },
          _frame_step>=1,_output_filename
        Apply a G'MIC command on all frames of the specified input video file, in a streamed way.
        If a display window is opened, rendered frames are displayed in it during processing.
        The output filename may have extension '.avi' (saved as a video), or any other usual image
        file extension (saved as a sequence of images).

        Default values: 'first_frame=0', 'last_frame=-1', 'frame_step=1' and
          'output_filename=(undefined)'.
    average_files:
        "filename_pattern",_first_frame>=0,_last_frame={ >=0 | -1=last },_frame_step>=1,
          _output_filename
        Average specified input image files, in a streamed way.
        If a display window is opened, rendered frames are displayed in it during processing.
        The output filename may have extension '.avi' (saved as a video), or any other usual image
        file extension (saved as a sequence of images).

        Default values: 'first_frame=0', 'last_frame=-1', 'frame_step=1' and
          'output_filename=(undefined)'.
    average_video:
        video_filename,_first_frame>=0,_last_frame={ >=0 | -1=last },_frame_step>=1,
          _output_filename
        Average frames of specified input video file, in a streamed way.
        If a display window is opened, rendered frames are displayed in it during processing.
        The output filename may have extension '.avi' (saved as a video), or any other usual image
        file extension (saved as a sequence of images).

        Default values: 'first_frame=0', 'last_frame=-1', 'frame_step=1' and
          'output_filename=(undefined)'.
    fade_files:
        "filename_pattern",_nb_inner_frames>0,_first_frame>=0,_last_frame={ >=0 |
          -1=last },_frame_step>=1,_output_filename
        Generate a temporal fading from specified input image files, in a streamed way.
        If a display window is opened, rendered frames are displayed in it during processing.
        The output filename may have extension 'avi' (saved as a video), or any other usual image
        file extension (saved as a sequence of images).

        Default values: 'nb_inner_frames=10', 'first_frame=0', 'last_frame=-1', 'frame_step=1' and
          'output_filename=(undefined)'.
    fade_video:
        video_filename,_nb_inner_frames>0,_first_frame>=0,_last_frame={ >=0 | -1=last },
          _frame_step>=1,_output_filename
        Create a temporal fading sequence from specified input video file, in a streamed way.
        If a display window is opened, rendered frames are displayed in it during processing.

        Default values: 'nb_inner_frames=10', 'first_frame=0', 'last_frame=-1', 'frame_step=1' and
          'output_filename=(undefined)'.
    files2video:
        "filename_pattern",_output_filename,_fps>0,_codec
        Convert several files into a single video file.

        Default values: 'output_filename=output.avi', 'fps=25' and 'codec=mp4v'.
    median_files:
        "filename_pattern",_first_frame>=0,_last_frame={ >=0 | -1=last },_frame_step>=1,
          _frame_rows[%]>=1,_is_fast_approximation={ 0 | 1 }
        Compute the median frame of specified input image files, in a streamed way.
        If a display window is opened, rendered frame is displayed in it during processing.

        Default values: 'first_frame=0', 'last_frame=-1', 'frame_step=1', 'frame_rows=20%' and
          'is_fast_approximation=0'.
    median_video:
        video_filename,_first_frame>=0,_last_frame={ >=0 | -1=last },_frame_step>=1,
          _frame_rows[%]>=1,_is_fast_approximation={ 0 | 1 }
        Compute the median of all frames of an input video file, in a streamed way.
        If a display window is opened, rendered frame is displayed in it during processing.

        Default values: 'first_frame=0', 'last_frame=-1', 'frame_step=1', 'frame_rows=100%' and
          'is_fast_approximation=1'.
    morph:
        nb_inner_frames>=1,_smoothness>=0,_precision>=0
        Create morphing sequence between selected images.

        Default values: 'smoothness=0.1' and 'precision=4'.
    morph_files:
        "filename_pattern",_nb_inner_frames>0,_smoothness>=0,_precision>=0,
          _first_frame>=0,_last_frame={ >=0 | -1=last },_frame_step>=1,_output_filename
        Generate a temporal morphing from specified input image files, in a streamed way.
        If a display window is opened, rendered frames are displayed in it during processing.
        The output filename may have extension '.avi' (saved as a video), or any other usual image
        file extension (saved as a sequence of images).

        Default values: 'nb_inner_frames=10', 'smoothness=0.1', 'precision=4', 'first_frame=0',
          'last_frame=-1', 'frame_step=1' and 'output_filename=(undefined)'.
    morph_video:
        video_filename,_nb_inner_frames>0,_smoothness>=0,_precision>=0,_first_frame>=0,
          _last_frame={ >=0 | -1=last },_frame_step>=1,_output_filename
        Generate a temporal morphing from specified input video file, in a streamed way.
        If a display window is opened, rendered frames are displayed in it during processing.
        The output filename may have extension '.avi' (saved as a video), or any other usual image
        file extension (saved as a sequence of images).

        Default values: 'nb_inner_frames=10', 'smoothness=0.1', 'precision=4', 'first_frame=0',
          'last_frame=-1', 'frame_step=1' and 'output_filename=(undefined)'.
    register_nonrigid:
        [destination],_smoothness>=0,_precision>0,_nb_scale>=0
        Register selected source images with specified destination image, using non-rigid warp.

        Default values: 'smoothness=0.2', 'precision=6' and 'nb_scale=0(auto)'.
    register_rigid:
        [destination],_smoothness>=0,_boundary_conditions={ 0=dirichlet | 1=neumann |
          2=periodic | 3=mirror }
        Register selected source images with specified destination image, using rigid warp (shift).

        Default values: 'smoothness=1' and 'boundary_conditions=0'.
    transition:
        [transition_shape],nb_added_frames>=0,100>=shading>=0,_single_frame_only={
          -1=disabled | >=0 }
        Generate a transition sequence between selected images.

        Default values: 'shading=0' and 'single_frame_only=-1'.
    transition3d:
        _nb_frames>=2,_nb_xtiles>0,_nb_ytiles>0,_axis_x,_axis_y,_axis_z,_is_antialias={ 0 | 1 }
        Create 3D transition sequence between selected consecutive images.
        'axis_x', 'axis_y' and 'axis_z' can be set as mathematical expressions, depending on 'x' and 'y'.

        Default values: 'nb_frames=10', 'nb_xtiles=nb_ytiles=3', 'axis_x=1', 'axis_y=1', 'axis_z=0' and
          'is_antialias=1'.
    video2files:
        input_filename,_output_filename,_first_frame>=0,_last_frame={ >=0 | -1=last },
          _frame_step>=1
        Split specified input video file into image files, one for each frame.
        First and last frames as well as step between frames can be specified.

        Default values: 'output_filename=frame.png', 'first_frame=0', 'last_frame=-1' and
          'frame_step=1'.
 ** Convenience Functions:
    alert:
        _title,_message,_label_button1,_label_button2,...
        Display an alert box and wait for user's choice.
        If a single image is in the selection, it is used as an icon for the alert box.

        Default values: 'title=[G'MIC Alert]' and 'message=This is an alert box.'.
    arg:
        n>=1,_arg1,...,_argN
        Return the n-th argument of the specified argument list.
    arg2var:
        variable_name,argument_1,...,argument_N
        For each i in [1...N], set 'variable_name$i=argument_i'.
        The variable name should be global to make this command useful (i.e. starts by an underscore).
    autocrop_coords:
        value1,value2,... | auto
        Return coordinates (x0,y0,z0,x1,y1,z1) of the autocrop that could be performed on the latest
        of the selected images.

        Default value: 'auto'
    average_colors:
        Return the average vector-value of the latest of the selected images.
    base642img:
        "base64_string"
        Decode given base64-encoded string as a newly inserted image at the end of the list.
        The argument string must have been generated using command 'img2base64'.
    base642uchar:
        "base64_string"
        Decode given base64-encoded string as a newly inserted 1-column image at the end of the list.
        The argument string must have been generated using command 'uchar2base64'.
    basename:
        file_path,_variable_name_for_folder
        Return the basename of a file path, and opt. its folder location.
        When specified 'variable_name_for_folder' must starts by an underscore
        (global variable accessible from calling function).
    bin:
        binary_int1,...
        Print specified binary integers into their octal, decimal, hexadecimal and string
          representations.
    bin2dec:
        binary_int1,...
        Convert specified binary integers into their decimal representations.
    covariance_colors:
        _avg_outvarname
        Return the covariance matrix of the vector-valued colors in the latest of the selected images
        (for arbitrary number of channels).
        Parameter 'avg_outvarname' is used as a variable name that takes the value of the average
          vector-value.
    dec:
        decimal_int1,...
        Print specified decimal integers into their binary, octal, hexadecimal and string
          representations.
    dec2str:
        decimal_int1,...
        Convert specifial decimal integers into its string representation.
    dec2bin:
        decimal_int1,...
        Convert specified decimal integers into their binary representations.
    dec2hex:
        decimal_int1,...
        Convert specified decimal integers into their hexadecimal representations.
    dec2oct:
        decimal_int1,...
        Convert specified decimal integers into their octal representations.
    fact:
        value
        Return the factorial of the specified value.
    fibonacci:
        N>=0
        Return the Nth number of the Fibonacci sequence.
    file_mv:
        filename_src,filename_dest
        Rename or move a file from a location $1 to another location $2.
    file_rand:
        Return a random filename for storing temporary data.
    file_rm:
        filename
        Delete a file.
    filename:
        filename,_number1,_number2,...,_numberN
        Return a filename numbered with specified indices.
    files (+):
        _mode,path
        Return the list of files and/or subfolders from specified path.
        'path' can be eventually a matching pattern.
        'mode' can be { 0=files only | 1=folders only | 2=files + folders }.
        Add '3' to 'mode' to return full paths instead of filenames only.

        Default value: 'mode=5'.
    fitratio_wh:
        min_width,min_height,ratio_wh
        Return a 2D size 'width,height' which is bigger than 'min_width,min_height' and has the
          specified w/h ratio.
    fitscreen:
        width,height,_depth,_minimal_size[%],_maximal_size[%] |
        [image],_minimal_size[%],_maximal_size[%]
        Return the 'ideal' size WxH for a window intended to display an image of specified size on screen.

        Default values: 'depth=1', 'minimal_size=128' and 'maximal_size=85%'.
    fontchart:
        Insert G'MIC font chart at the end of the image list.
    fps:
        Return the number of time this function is called per second, or -1 if this info is not yet
          available.
        Useful to display the framerate when displaying animations.
    gcd:
        a,b
        Return the GCD (greatest common divisor) between a and b.
    hex:
        hexadecimal_int1,...
        Print specified hexadecimal integers into their binary, octal, decimal and string
          representations.
    hex2dec:
        hexadecimal_int1,...
        Convert specified hexadecimal integers into their decimal representations.
    hex2img:
        "hexadecimal_string"
        Insert new image 1xN at the end of the list with values specified by the given
          hexadecimal-encoded string.
    hex2str:
        hexadecimal_string
        Convert specified hexadecimal string into a string.
    img2base64:
        _encoding={ 0=base64 | 1=base64url }
        Encode selected images as a base64-encoded string.
        The images can be then decoded using command 'base642img'.

        Default values: 'encoding=0'.
    img2hex:
        Return representation of last image as an hexadecimal-encoded string.
        Input image must have values that are integers in [0,255].
    img2str:
        Return the content of the latest of the selected images as a special G'MIC input string.
    img2text:
        _line_separator
        Return text contained in a multi-line image.

        Default value: 'line_separator= '.
    img82hex:
        Convert selected 8bits-valued vectors into their hexadecimal representations (ascii-encoded).
    hex2img8:
        Convert selected hexadecimal representations (ascii-encoded) into 8bits-valued vectors.
    is_3d:
        Return 1 if all of the selected images are 3D objects, 0 otherwise.
    is_change:
        _value={ 0=false | 1=true }
        Set or unset the 'is_change' flag associated to the image list.
        This flag tells the interpreter whether or not the image list should be displayed when the
          pipeline ends.

        Default value: 'value=1'.
    is_half:
        Return 1 if the type of image pixels is limited to half-float.
    is_ext:
        filename,_extension
        Return 1 if specified filename has a given extensioin.
    is_image_arg:
        string
        Return 1 if specified string looks like '[ind]'.
    is_pattern:
        string
        Return 1 if specified string looks like a drawing pattern '0x......'.
    is_percent:
        string
        Return 1 if specified string ends with a '%', 0 otherwise.
    is_videofilename:
        Return 1 if extension of specified filename is typical from video files.
    is_windows:
        Return 1 if current computer OS is Windows, 0 otherwise.
    math_lib:
        Return string that defines a set of several useful macros for the embedded math evaluator.
    mad:
        Return the MAD (Maximum Absolute Deviation) of the last selected image.
        The MAD is defined as MAD = med_i|x_i-med_j(x_j)|
    max_w:
        Return the maximal width between selected images.
    max_h:
        Return the maximal height between selected images.
    max_d:
        Return the maximal depth between selected images.
    max_s:
        Return the maximal spectrum between selected images.
    max_wh:
        Return the maximal wxh size of selected images.
    max_whd:
        Return the maximal wxhxd size of selected images.
    max_whds:
        Return the maximal wxhxdxs size of selected images.
    med:
        Return the median value of the last selected image.
    median_color:
        Return the median color value of the last selected image.
    min_w:
        Return the minimal width between selected images.
    min_h:
        Return the minimal height between selected images.
    min_d:
        Return the minimal depth between selected images.
    min_s:
        Return the minimal s size of selected images.
    min_wh:
        Return the minimal wxh size of selected images.
    min_whd:
        Return the minimal wxhxd size of selected images.
    min_whds:
        Return the minimal wxhxdxs size of selected images.
    named (+):
        _mode,"name1","name2",...
        Return the set of indices corresponding to images of the selection with specified names.
        After this command returns, the status contains a list of indices (unsigned integers),
        separated by commas (or an empty string if no images with those names have been found).
        (eq. to 'nmd').
        'mode' can be { 0=all indices (default) | 1=lowest index | 2=highest index | 3 = all indices
          (case insensitive) | 4 = lowest index (case insensitive) | 5 = highest index (case insensitive)}
    normalize_filename:
        filename
        Return a "normalized" version of the specified filename, without spaces and capital letters.
    oct:
        octal_int1,...
        Print specified octal integers into their binary, decimal, hexadecimal and string
          representations.
    oct2dec:
        octal_int1,...
        Convert specified octal integers into their decimal representations.
    padint:
        number,_size>0
        Return a integer with 'size' digits (eventually left-padded with '0').
    path_cache:
        Return a path to store G'MIC data files for one user (whose value is OS-dependent).
    path_gimp:
        Return a path to store GIMP configuration files for one user (whose value is OS-dependent).
    path_tmp:
        Return a path to store temporary files (whose value is OS-dependent).
    reset:
        Reset global parameters of the interpreter environment.
    RGB:
        Return a random int-valued RGB color.
    RGBA:
        Return a random int-valued RGBA color.
    std_noise:
        Return the estimated noise standard deviation of the last selected image.
    str:
        string
        Print specified string into its binary, octal, decimal and hexadecimal representations.
    str2hex:
        string
        Convert specified string into a sequence of hexadecimal values.
    strcontains:
        string1,string2
        Return 1 if the first string contains the second one.
    strlen:
        string1
        Return the length of specified string argument.
    strreplace:
        string,search,replace
        Search and replace substrings in an input string.
    strlowercase:
        string
        Return a lower-case version of the specified string.
    strvar:
        string
        Return a simplified version of the specified string, that can be used as a variable name.
    strver:
        _version
        Return the specified version number of the G'MIC interpreter, as a string.

        Default value: 'version=$_version'.
    tic:
        Initialize tic-toc timer.
        Use it in conjunction with 'toc'.
    toc:
        Display elapsed time of the tic-toc timer since the last call to 'tic'.
        This command returns the elapsed time in the status value.
        Use it in conjunction with 'tic'.
    to_clutname:
        "string"
        Return simplified name that can be used as a CLUT name, from specified input string.
    uchar2base64:
        _encoding={ 0=base64 | 1=base64url }
        Encode the values of the latest of the selected images as a base64-encoded string.
        The string can be decoded using command 'base642uchar'.
        Selected images must have values that are integers in [0,255].

        Default values: 'encoding=0'.
 ** Other Interactive Commands:
    demo:
        _run_in_parallel={ 0=no | 1=yes | 2=auto }
        Show a menu to select and view all G'MIC interactive demos.
    x_2048:
        Launch the 2048 game.
    x_blobs:
        Launch the blobs editor.
    x_bouncing:
        Launch the bouncing balls demo.
    x_color_curves:
        _colorspace={ rgb | cmy | cmyk | hsi | hsl | hsv | lab | lch | ycbcr | last }
        Apply color curves on selected RGB[A] images, using an interactive window.
        Set 'colorspace' to 'last' to apply last defined color curves without opening interactive windows.

        Default value: 'colorspace=rgb'.
    x_colorize:
        _is_lineart={ 0 | 1 },_max_resolution={ 0 | >=128 },_multichannels_output={ 0 |
          1 },_[palette1],_[palette2],_[grabber1]
        Colorized selected B&W images, using an interactive window.
        When >0, argument 'max_resolution' defines the maximal image resolution used in the interactive window.

        Default values: 'is_lineart=1', 'max_resolution=1024' and 'multichannels_output=0'.
    x_connect4:
        Launch the Connect Four game.
    x_crop:
        Crop selected images interactively.
        (eq. to 'xz').
    x_cut:
        Cut selected images interactively.
    x_fire:
        Launch the fire effect demo.
    x_fireworks:
        Launch the fireworks demo.
    x_fisheye:
        Launch the fish-eye effect demo.
    x_fourier:
        Launch the fourier filtering demo.
    x_grab_color:
        _variable_name
        Open a color grabber widget from the first selected image.
        Argument 'variable_name' specifies the variable that contains the selected color values at any time.
        Assigning '-1' to it forces the interactive window to close.

        Default values: 'variable_name=xgc_variable'.
    x_hanoi:
        Launch the Tower of Hanoi game.
    x_histogram:
        Launch the histogram demo.
    x_hough:
        Launch the hough transform demo.
    x_jawbreaker:
        0<_width<20,0<_height<20,0<_balls<=8
        Launch the Jawbreaker game.
    x_landscape:
        Launch the virtual landscape demo.
    x_life:
        Launch the game of life.
    x_light:
        Launch the light effect demo.
    x_mandelbrot:
        _julia={ 0 | 1 },_c0r,_c0i
        Launch Mandelbrot/Julia explorer.
    x_mask_color:
        _colorspace={ all | rgb | lrgb | ycbcr | lab | lch | hsv | hsi | hsl | cmy |
          cmyk | yiq },_spatial_tolerance>=0,_color_tolerance>=0
        Interactively select a color, and add an alpha channel containing the corresponding color mask.
        Argument 'colorspace' refers to the color metric used to compute color similarities, and can be basically
        one of { rgb | lrgb | ycbcr | lab | lch | hsv | hsi | hsl | cmy | cmyk | yiq }.
        You can also select one one particular channel of this colorspace, by setting 'colorspace' as
        'colorspace_channel' (e.g. 'hsv_h' for the hue).

        Default values: 'colorspace=all', 'spatial_tolerance=5' and 'color_tolerance=5'.
    x_metaballs3d:
        Launch the 3D metaballs demo.
    x_minesweeper:
        8<=_width=<20,8<=_height<=20
        Launch the Minesweeper game.
    x_minimal_path:
        Launch the minimal path demo.
    x_morph:
        _nb_frames>=2,_preview_fidelity={ 0=coarsest | 1=coarse | 2=normal | 3=fine |
          4=finest }
        Launch the interactive image morpher.

        Default values: 'nb_frames=16' and 'preview_fidelity=3'.
    x_pacman:
        Launch pacman game.
    x_paint:
        Launch the interactive painter.
    x_plasma:
        Launch the plasma effect demo.
    x_quantize_rgb:
        _nbcolors>=2
        Launch the RGB color quantization demo.
    x_reflection3d:
        Launch the 3D reflection demo.
    x_rubber3d:
        Launch the 3D rubber object demo.
    x_segment:
        _max_resolution={ 0 | >=128 }
        Segment foreground from background in selected opaque RGB images, interactively.
        Return RGBA images with binary alpha-channels.

        Default value: 'max_resolution=1024'.
    x_select_color:
        _variable_name
        Display a RGB or RGBA color selector.
        Argument 'variable_name' specifies the variable that contains the selected color values (as R,G,B,[A])
        at any time.
        Its value specifies the initial selected color. Assigning '-1' to it forces the interactive
          window to close.

        Default value: 'variable_name=xsc_variable'.
    x_select_function1d:
        _variable_name,_background_curve_R,_background_curve_G,_background_curve_B
        Open an interactive window, where the user can defined its own 1D function.
        If an image is selected, it is used to display additional information :
        - The first row defines the values of a background curve displayed on the window (e.g. an
          histogram).
        - The 2nd, 3rd and 4th rows define the R,G,B color components displayed beside the X and Y axes.
        Argument 'variable_name' specifies the variable that contains the selected function keypoints
          at any time.
        Assigning '-1' to it forces the interactive window to close.

        Default values: 'variable_name=xsf_variable', 'background_curve_R=220',
          'background_curve_G=background_curve_B=background_curve_T'.
    x_select_palette:
        _variable_name,_number_of_columns={ 0=auto | >0 }
        Open a RGB or RGBA color selector widget from a palette.
        The palette is given as a selected image.
        Argument 'variable_name' specifies the variable that contains the selected color values (as R,G,B,[A])
        at any time.
        Assigning '-1' to it forces the interactive window to close.

        Default values: 'variable_name=xsp_variable' and 'number_of_columns=2'.
    x_shadebobs:
        Launch the shade bobs demo.
    x_spline:
        Launch spline curve editor.
    x_starfield3d:
        Launch the 3D starfield demo.
    x_tetris:
        Launch tetris game.
    x_threshold:
        Threshold selected images interactively.
    x_tictactoe:
        Launch tic-tac-toe game.
    x_warp:
        _nb_keypoints_xgrid>=2,_nb_keypoints_ygrid>=2,_nb_keypoints_contours>=0,
          _preview_fidelity={ 0=coarsest | 1=coarse | 2=normal | 3=fine | 4=finest }
        Launch the interactive image warper.

        Default values: 'nb_keypoints_xgrid=nb_keypoints_ygrid=2', 'nb_keypoints_contours=0' and
          'preview_fidelity=1'.
    x_waves:
        Launch the image waves demo.
    x_whirl:
        _opacity>=0
        Launch the fractal whirls demo.

        Default values: 'opacity=0.2'.
 **** Command shortcuts:
    != (+): eq. to 'neq'.
    % (+): eq. to 'mod'.
    & (+): eq. to 'and'.
    * (+): eq. to 'mul'.
    *3d (+): eq. to 'mul3d'.
    + (+): eq. to 'add'.
    +3d (+): eq. to 'add3d'.
    - (+): eq. to 'sub'.
    -3d (+): eq. to 'sub3d'.
    / (+): eq. to 'div'.
    /3d (+): eq. to 'div3d'.
    < (+): eq. to 'lt'.
    << (+): eq. to 'bsl'.
    <= (+): eq. to 'le'.
    = (+): eq. to 'set'.
    == (+): eq. to 'eq'.
    > (+): eq. to 'gt'.
    >= (+): eq. to 'ge'.
    >> (+): eq. to 'bsr'.
    ^ (+): eq. to 'pow'.
    a (+): eq. to 'append'.
    ac : eq. to 'apply_channels'.
    ap : eq. to 'apply_parallel'.
    apc : eq. to 'apply_parallel_channels'.
    apo : eq. to 'apply_parallel_overlap'.
    at : eq. to 'apply_tiles'.
    b (+): eq. to 'blur'.
    c (+): eq. to 'cut'.
    c3d : eq. to 'center3d'.
    col3d (+): eq. to 'color3d'.
    d (+): eq. to 'display'.
    d0 : eq. to 'display0'.
    d2d : eq. to 'display2d'.
    d3d (+): eq. to 'display3d'.
    da : eq. to 'display_array'.
    db3d (+): eq. to 'double3d'.
    dfft : eq. to 'display_fft'.
    dg : eq. to 'display_graph'.
    dh : eq. to 'display_histogram'.
    dp : eq. to 'display_parallel'.
    dp0 : eq. to 'display_parallel0'.
    dq : eq. to 'display_quiver'.
    drgba : eq. to 'display_rgba'.
    dt : eq. to 'display_tensors'.
    dw : eq. to 'display_warp'.
    e (+): eq. to 'echo'.
    endl (+): eq. to 'endlocal'.
    f (+): eq. to 'fill'.
    f3d (+): eq. to 'focale3d'.
    fc : eq. to 'fill_color'.
    fi (+): eq. to 'endif'.
    frame : eq. to 'frame_xy'.
    g (+): eq. to 'gradient'.
    h : eq. to 'help'.
    i (+): eq. to 'input'.
    ig : eq. to 'input_glob'.
    ir : eq. to 'inrange'.
    j (+): eq. to 'image'.
    j3d (+): eq. to 'object3d'.
    k (+): eq. to 'keep'.
    l (+): eq. to 'local'.
    l3d (+): eq. to 'light3d'.
    m (+): eq. to 'command'.
    m* (+): eq. to 'mmul'.
    m/ (+): eq. to 'mdiv'.
    m3d (+): eq. to 'mode3d'.
    md3d (+): eq. to 'moded3d'.
    mv (+): eq. to 'move'.
    n (+): eq. to 'normalize'.
    n3d : eq. to 'normalize3d'.
    nm (+): eq. to 'name'.
    nmd (+): eq. to 'named'.
    o (+): eq. to 'output'.
    o3d (+): eq. to 'opacity3d'.
    on : eq. to 'outputn'.
    op : eq. to 'outputp'.
    ow : eq. to 'outputw'.
    ox : eq. to 'outputx'.
    p (+): eq. to 'print'.
    p3d : eq. to 'primitives3d'.
    q (+): eq. to 'quit'.
    r (+): eq. to 'resize'.
    r2dx : eq. to 'resize2dx'.
    r2dy : eq. to 'resize2dy'.
    r3d (+): eq. to 'rotate3d'.
    r3dx : eq. to 'resize3dx'.
    r3dy : eq. to 'resize3dy'.
    r3dz : eq. to 'resize3dz'.
    rm (+): eq. to 'remove'.
    rr2d : eq. to 'resize_ratio2d'.
    rv (+): eq. to 'reverse'.
    rv3d (+): eq. to 'reverse3d'.
    s (+): eq. to 'split'.
    s3d (+): eq. to 'split3d'.
    sh (+): eq. to 'shared'.
    sl3d (+): eq. to 'specl3d'.
    sp : eq. to 'sample'.
    ss3d (+): eq. to 'specs3d'.
    t (+): eq. to 'text'.
    t3d : eq. to 'texturize3d'.
    to : eq. to 'text_outline'.
    u (+): eq. to 'status'.
    up : eq. to 'update'.
    v (+): eq. to 'verbose'.
    w (+): eq. to 'window'.
    x (+): eq. to 'exec'.
    xz : eq. to 'x_crop'.
    y (+): eq. to 'unroll'.
    z (+): eq. to 'crop'.
    | (+): eq. to 'or'.
   [ Total number of commands: 1002 ]
 13. Examples of use
 'gmic' is a generic image processing tool which can be used in a wide variety of situations.
 The few examples below illustrate possible uses of this tool:

  - View a list of images:
     gmic file1.bmp file2.jpeg

  - Convert an image file:
     gmic input.bmp output output.jpg

  - Create a volumetric image from a movie sequence:
     gmic input.mpg append z output output.hdr

  - Compute image gradient norm:
     gmic input.bmp gradient_norm

  - Denoise a color image:
     gmic image.jpg denoise 30,10 output denoised.jpg

  - Compose two images using overlay layer blending:
     gmic image1.jpg image2.jpg blend overlay output blended.jpg

  - Evaluate a mathematical expression:
     gmic echo "cos(pi/4)^2+sin(pi/4)^2={cos(pi/4)^2+sin(pi/4)^2}"

  - Plot a 2D function:
     gmic 1000,1,1,2 fill "X=3*(x-500)/500;X^2*sin(3*X^2)+if(c==0,u(0,-1),cos(X*10))" plot

  - Plot a 3D elevated function in random colors:
     gmic 128,128,1,3,"u(0,255)" plasma 10,3 blur 4 sharpen 10000 \
      elevation3d[-1] "'X=(x-64)/6;Y=(y-64)/6;100*exp(-(X^2+Y^2)/30)*abs(cos(X)*sin(Y))'"

  - Plot the isosurface of a 3D volume:
     gmic mode3d 5 moded3d 5 double3d 0 isosurface3d "'x^2+y^2+abs(z)^abs(4*cos(x*y*z*3))'",3

  - Render a G'MIC 3D logo:
     gmic 0 text G\'MIC,0,0,53,1,1,1,1 expand_xy 10,0 blur 1 normalize 0,100 +plasma 0.4 add \
      blur 1 elevation3d -0.1 moded3d 4

  - Generate a 3D ring of torii:
     gmic repeat 20 torus3d 15,2 color3d[-1] "{u(60,255)},{u(60,255)},{u(60,255)}" \
      *3d[-1] 0.5,1 if "{$>%2}" rotate3d[-1] 0,1,0,90 fi add3d[-1] 70 add3d \
      rotate3d 0,0,1,18 done moded3d 3 mode3d 5 double3d 0

  - Create a vase from a 3D isosurface:
     gmic moded3d 4 isosurface3d "'x^2+2*abs(y/2)*sin(2*y)^2+z^2-3',0" sphere3d 1.5 \
      sub3d[-1] 0,5 plane3d 15,15 rotate3d[-1] 1,0,0,90 center3d[-1] add3d[-1] 0,3.2 \
      color3d[-1] 180,150,255 color3d[-2] 128,255,0 color3d[-3] 255,128,0 add3d

  - Display filtered webcam stream:
     gmic apply_camera \"+mirror x +mirror y add div 4\"

  - Launch a set of G'MIC interactive demos:
     gmic demo
 ** G'MIC comes with ABSOLUTELY NO WARRANTY; for details visit: https://gmic.eu **