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Graphics::Toolkit::Color::Space::Hub(3) User Contributed Perl Documentation Graphics::Toolkit::Color::Space::Hub(3)


Graphics::Toolkit::Color::Space::Hub - convert, format and measure color values


Central hub for all color value related math. Can handle vectors of all spaces mentioned in next paragraph and translates also into and from different formats such as RGB hex ('#AABBCC').

    use Graphics::Toolkit::Color::Space::Hub;
    my $true = Graphics::Toolkit::Color::Space::Hub::is_space( 'HSL' );
    my $HSL = Graphics::Toolkit::Color::Space::Hub::get_space( 'HSL');
    my $RGB = Graphics::Toolkit::Color::Space::Hub::base_space();
    Graphics::Toolkit::Color::Space::Hub::space_names();     # all space names
    $HSL->normalize([240,100, 0]);         # 2/3, 1, 0
    $HSL->convert([240, 100, 0], 'RGB');   #   0, 0, 1
    $HSL->deconvert([0, 0, 1], 'RGB');     # 2/3, 1, 0
    $RGB->denormalize([0, 0, 1]);          #   0, 0, 255
    $RGB->format([0, 0, 255], 'hex');      #   '#0000ff'
    my ($values, $space_name) = Graphics::Toolkit::Color::Space::Hub::deformat( '#0000ff' );
    # [0, 0, 255] , 'RGB'


This module is supposed to be used by Graphics::Toolkit::Color and not directly, thus it exports no symbols and has a much less DWIM API then the main module.


Color space names can be written in any combination of upper and lower case.


has three integer values: red (0 .. 255), green (0 .. 255) and blue (0 .. 255). All are scaling from no (0) to very much (255) light of that color, so that (0,0,0) is black, (255,255,255) is white and (0,0,255) is blue.


is the inverse of RGB but with the range: 0 .. 1. cyan is the inverse value of red, magenta is inverse green and yellow is inverse of blue. Inverse meaning when a color has the maximal red value, it has to have the minimal cyan value.


is an extension of CMY with a fourth value named key (also 0 .. 1), which is basically the amount of black mixed into the CMY color.


has three integer values: hue (0 .. 359), saturation (0 .. 100) and lightness (0 .. 100). Hue stands for a color on a rainbow: 0 = red, 15 approximates orange, 60 - yellow 120 - green, 180 - cyan, 240 - blue, 270 - violet, 300 - magenta, 330 - pink. 0 and 360 point to the same coordinate. This module only outputs 0, even if accepting 360 as input. saturation ranges from 0 = gray to 100 - clearest color set by hue. lightness ranges from 0 = black to 50 (hue or gray) to 100 = white.


Similar to HSL we have hue and saturation, but the third value in named value. In HSL the color white is always achieved when lightness = 100. In HSV additionally saturation has to be zero to get white. When in HSV value is 100 and saturation is also 100, than we have the brightest clearest color of whatever hue sets.


It is an alias to HSV, just value being renamed with brightness.


An inverted HSV, where the clean colors are inside of the cylinder. It still has the circular hue dimension, as described in "HSL". The other two, linear dimensions (also 0 .. 100 [percent]) are whiteness and blackness, desribing how much white or black are mixed in. If both are zero, than we have a pure color. whiteness of 100 always leads to pure white and blackness of 100 always leads to pure black.


Has the linear dimensions luminance (sort of brightness, range 0..1), in-phase (cyan - orange - balance, range -0.5959 .. 0.5959) and quadrature (magenta - green - balance, range: -0.5227 .. 0.5227).


These formats are available in all color spaces.


    'RGB: 10, 20, 30'


    'rgb(10, 20, 30)'


    [RGB, 10, 20, 30]


    { red => 10, green => 20, blue => 30 }


    { r => 10, g => 20, b => 30 }


This package provides two sets of routines. Thes first is just a lookup of what color space objects are available. The second set consists of three pairs or routines about 3 essential operations of number values and their reversal. The full pipeline for the translation of color values is:

    1. deformat (into a value list)
    2. normalize (into 0..1 range)
    3. convert/deconvert (into target color space)
    4. denormalize (into target range)
    5. format (into target format)


Returns a list of string values, which are the names of all available color space. See "COLOR-SPACES".


Needs one argument, that supposed to be a color space name. If it is, the result is an 1, otherwise 0 (perlish pseudo boolean).


Needs one argument, that supposed to be a color space name. If it is, the result is the according color space object, otherwise undef.


Return the color space object of (currently) RGB name space. This name space is special since every color space object provides converters from and to RGB, but the RGB itself has no converter.


Normal in a mathematical sense means the range of acceptable values are between zero and one. Normalization means there for altering the values of numbers to fit in that range. For instance standard RGB values are integers between zero and 255. Normalizing them essentially means just dividing them with 255.

    my @rgb = Graphics::Toolkit::Color::Space::Hub::normalize( [0,10,255], 'RGB' );

It has one required and two optional arguments. The first is an ARRAY ref with the vector or values of a color. The seond argument is name of a color space. This is in most cases necessary, since all color space know their standard value ranges (being e.g. 3 x 0 .. 255 for RGB). If you want to normalize from special ranges like RGB16 you have use the third argument, which has to be a valid value range definition.

    my @rgb = Graphics::Toolkit::Color::Space::Hub::normalize( [0, 1000, 34000], 'RGB', 2**16 );
    # which is the same as:
    my @rgb = Graphics::Toolkit::Color::Space::Hub::normalize( [0, 1000, 34000], 'RGB', [[0,65536].[0,65536].[0,65536]] );


Reverse function of normalize, taking the same arguments. If result has to be an integer (range maximum above 1), it will be rounded.

    my @rgb = Graphics::Toolkit::Color::Space::Hub::denormalize( [0,0.1,1], 'RGB' );
    my @rgb = Graphics::Toolkit::Color::Space::Hub::denormalize( [0,0.1,1], 'RGB', 2**16 );


Converts a value vector (first argument) from base space (RGB) into any space mentioned space (second argument - see "COLOR-SPACES"). The values have to be normalized (inside 0..1). If there are outside the acceptable range, there will be clamped, so that the result will also normal.

    # convert from RGB to  HSL
    my @hsl = Graphics::Toolkit::Color::Space::Hub::convert( [0.1, 0.5, .7], 'HSL' );


Converts a value tuple (vector - firs argument) of any color space (second argument) into the base space (RGB).

    # convert from HSL to RGB
    my @rgb = Graphics::Toolkit::Color::Space::Hub::deconvert( [0.9, 0.5, 0.5], 'HSL' );


Putting a list of values (inside an ARRAY ref - first argument) from any supported color space (second argument) into another data format (third argument, see /FORMATS).

    my $hex = Graphics::Toolkit::Color::Space::Hub::format( [255, 0, 10], 'hex' );       # 'ff00a0'
    my $string = Graphics::Toolkit::Color::Space::Hub::format( [255, 0, 10], 'string' ); # 'RGB: 255, 0, 10'


Reverse function of format, but also guesses the color space. That's why it takes only one argument, a scalar that can be a string, ARRAY ref or HASH ref. The result will be two values. The first is a ARRAY with all the unaltered, not clamped and not normalized values. The second is the name of the recognized color name space.

    my ($values, $space) =  Graphics::Toolkit::Color::Space::Hub::deformat( 'ff00a0' );
    # [255, 10 , 0], 'RGB'
    ($values, $space) =  Graphics::Toolkit::Color::Space::Hub::deformat( [255, 10 , 0] ); # same result


This is a special case deformat routine for the hash and char_hash format (see /FORMATS). It can tolerate missing values. The The result will also be a hash




Copyright 2023 Herbert Breunung.

This program is free software; you can redistribute it and/or modify it under same terms as Perl itself.


Herbert Breunung, <>

2024-03-08 perl v5.40.0