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


Graphics::Toolkit::Color - color palette constructor


    use Graphics::Toolkit::Color qw/color/;
    my $red = Graphics::Toolkit::Color->new('red'); # create color object
    say $red->add( 'blue' => 255 )->name;           # add blue value: 'fuchsia'
    my $blue = color( 0, 0, 255)->values('HSL');    # 240, 100, 50 = blue
    $blue->blend( with => [HSL => 0,0,80], pos => 0.1);# mix blue with a little grey in HSL
    $red->gradient( to => '#0000FF', steps => 10);  # 10 colors from red to blue
    $red->complement( 3 );                          # get fitting red green and blue


ATTENTION: deprecated methods of the old API ( string, rgb, red, green, blue, rgb_hex, rgb_hash, hsl, hue, saturation, lightness, hsl_hash, blend_with, gradient_to, rgb_gradient_to, hsl_gradient_to, complementary) will be removed on version 2.0.

Graphics::Toolkit::Color, for short GTC, is the top level API of this module and the only one a regular user should be concerned with. Its main purpose is the creation of sets of related colors, such as gradients, complements and others.

GTC are read only color holding objects with no additional dependencies. Create them in many different ways (see section "CONSTRUCTOR"). Access its values via methods from section "GETTER". Measure differences with the distance method. "SINGLE-COLOR" methods create one a object that is related to the current one and "COLOR-SETS" methods will create a host of color that are not only related to the current color but also have relations between each other.

While this module can understand and output color values in many spaces, such as YIQ, HSL and many more, RGB is the (internal) primal one, because GTC is about colors that can be shown on the screen, and these are usually encoded in RGB.

Humans access colors on hardware level (eye) in RGB, on cognition level in HSL (brain) and on cultural level (language) with names. Having easy access to all three and some color math should enable you to get the color palette you desire quickly.


There are many options to create a color objects. In short you can either use the name of a constant or provide values in one of several "COLOR-SPACES" in Graphics::Toolkit::Color::Space::Hub, which also can be formatted in many ways as described in this paragraph.


Get a color by providing a name from the X11, HTML (CSS) or SVG standard or a Pantone report. UPPER or CamelCase will be normalized to lower case and inserted underscore letters ('_') will be ignored as perl does in numbers (1_000 == 1000). All available names are listed under "NAMES" in Graphics::Toolkit::Color::Name::Constant. (See also: "name")

    my $color = Graphics::Toolkit::Color->new('Emerald');
    my @names = Graphics::Toolkit::Color::Name::all(); # select from these


Get a color by name from a specific scheme or standard as provided by an external module Graphics::ColorNames::* , which has to be installed separately. * is a placeholder for the pallet name, which might be: Crayola, CSS, EmergyC, GrayScale, HTML, IE, Mozilla, Netscape, Pantone, PantoneReport, SVG, VACCC, Werner, Windows, WWW or X. In ladder case Graphics::ColorNames::X has to be installed. You can get them all at once via Bundle::Graphics::ColorNames. The color name will be normalized as above.

    my $color = Graphics::Toolkit::Color->new('SVG:green');
    my @s = Graphics::ColorNames::all_schemes();          # look up the installed


Color definitions in hexadecimal format as widely used in the web, are also acceptable.

    my $color = Graphics::Toolkit::Color->new('#FF0000');
    my $color = Graphics::Toolkit::Color->new('#f00');    # works too

new( [$r, $g, $b] )

Triplet of integer RGB values (red, green and blue : 0 .. 255). Out of range values will be corrected to the closest value in range.

    my $red = Graphics::Toolkit::Color->new( 255, 0, 0 );
    my $red = Graphics::Toolkit::Color->new([255, 0, 0]);        # does the same
    my $red = Graphics::Toolkit::Color->new('RGB' => 255, 0, 0);  # named tuple syntax
    my $red = Graphics::Toolkit::Color->new(['RGB' => 255, 0, 0]); # named ARRAY

The named array syntax of the last example, as any here following, work for any supported color space.

new({ r => $r, g => $g, b => $b })

Hash with the keys 'r', 'g' and 'b' does the same as shown in previous paragraph, only more declarative. Casing of the keys will be normalised and only the first letter of each key is significant.

    my $red = Graphics::Toolkit::Color->new( r => 255, g => 0, b => 0 );
    my $red = Graphics::Toolkit::Color->new({r => 255, g => 0, b => 0}); # works too
                        ... ->new( Red => 255, Green => 0, Blue => 0);   # also fine
              ... ->new( Hue => 0, Saturation => 100, Lightness => 50 ); # same color
                  ... ->new( Hue => 0, whiteness => 0, blackness => 0 ); # still the same

new('rgb: $r, $g, $b')

String format (good for serialisation) that maximizes readability.

    my $red = Graphics::Toolkit::Color->new( 'rgb: 255, 0, 0' );
    my $blue = Graphics::Toolkit::Color->new( 'HSV: 240, 100, 100' );


Variant of string format that is supported by CSS.

    my $red = Graphics::Toolkit::Color->new( 'rgb(255, 0, 0)' );
    my $blue = Graphics::Toolkit::Color->new( 'hsv(240, 100, 100)' );


If writing

    Graphics::Toolkit::Color->new( ...);

is too much typing for you or takes to much space, import the subroutine "color", which takes all the same arguments as described above.

    use Graphics::Toolkit::Color qw/color/;
    my $green = color('green');
    my $darkblue = color([20, 20, 250]);


giving access to different parts of the objects data.


String with normalized name (lower case without '_') of the color as in X11 or HTML (SVG) standard or the Pantone report. The name will be found and filled in, even when the object was created numerical values. If no color is found, "name" returns an empty string. All names are at: "NAMES" in Graphics::Toolkit::Color::Name::Constant (See als: "new('name')")


Returns the values of the color in given color space and format. It accepts three named, optional arguments.

First argument is the name of a color space (named argument "in"). All options are under: "COLOR-SPACES" in Graphics::Toolkit::Color::Space::Hub The order of named arguments is of course chosen by the user, but I call it the first (most important) argument, because if you give the method only one value, it is assumed to be the color space.

Second argument is the format (name: "as"). In short any SCALAR format acceptable to the "CONSTRUCTOR" can also be reproduced by a getter method and the numerical cases by this one. Not all formats are available under all color spaces, but the always present options are: "list" (default), "hash", "char_hash" and "array".

Third named argument is the range inside which the numerical values have to be. RGB are normally between 0 .. 255 and CMYK between 0 .. 1 ('normal'). Only a range of 1 a.k.a. 'normal' displays decimals. There are three syntax option to set the ranges. One value will be understood as upper limit of all dimensions and zero being the lower one. If you want to set the upper limits of all dimensions separately, you have to deliver an ARRAY ref with the 3 or 4 upper limits. To also define the lower boundary, you replace the number with an ARRAY ref containing the lower and then the upper limit.

    $blue->values();                               # get list in RGB: 0, 0, 255
    $blue->values( in => 'RGB', as => 'list');     # same call
    $blue->values( in => 'RGB', as => 'hash');     # { red => 0, green => 0, blue => 255}
    $blue->values( in => 'RGB', as => 'char_hash');# { r => 0, g => 0, b => 255}
    $blue->values( in => 'RGB', as => 'hex');      # '#00FFFF'
    $color->values('HSL');                         # 240, 100, 50
    $color->values( in => 'HSL', range => 1);      # 0.6666, 1, 0.5
    $color->values( in => 'RGB', range => 2**16);  # values in RGB16
    $color->values( in => 'HSB', as => 'hash')->{'hue'};  # how to get single values
   ($color->values( 'HSB'))[0];                           # same, but shorter


Is a floating point number that measures the Euclidean distance between two colors. One color is the calling object itself and the second (C2) has to provided as a named argument (to), which is the only required one. It ca come in the form of a second GTC object or any scalar color definition new would accept. The distance is measured in HSL color space unless told otherwise by the argument in. The third argument is named metric. It's useful if you want to notice only certain dimensions. Metric is the long or short name of that dimension or the short names of several dimensions. They all have to come from one color space and one shortcut letter can be used several times to heighten the weight of this dimension. The last argument in named range and is a range definition, unless you don't want to compute the distance with the default ranges of the selected color space.

    my $d = $blue->distance( to => 'lapisblue' );              # how close is blue to lapis color?
    $d = $blue->distance( to => 'airyblue', in => 'RGB', select => 'Blue'); # same amount of blue?
    $d = $color->distance( to => $c2, in => 'HSL', select => 'hue' );                  # same hue?
    # compute distance when with all value ranges 0 .. 1
    $d = $color->distance( to => $c2, in => 'HSL', select => 'hue', range => 'normal' );


construct colors that are related to the current object.


Create a new object that differs in certain values defined in the arguments as a hash.

    $black->set( blue => 255 )->name;   # blue, same as #0000ff
    $blue->set( saturation => 50 );     # pale blue, same as $blue->set( s => 50 );


Create a Graphics::Toolkit::Color object, by adding any RGB or HSL values to current color. (Same rules apply for key names as in new - values can be negative.) RGB and HSL can be combined, but please note that RGB are applied first.

If the first argument is a Graphics::Toolkit::Color object, than RGB values will be added. In that case an optional second argument is a factor (default = 1), by which the RGB values will be multiplied before being added. Negative values of that factor lead to darkening of result colors, but its not subtractive color mixing, since this module does not support CMY color space. All RGB operations follow the logic of additive mixing, and the result will be rounded (clamped), to keep it inside the defined RGB space.

    my $blue = Graphics::Toolkit::Color->new('blue');
    my $darkblue = $blue->add( Lightness => -25 );
    my $blue2 = $blue->add( blue => 10 );        # this is bluer than blue


Create a Graphics::Toolkit::Color object, that has the average values between the calling object (color 1 - C1) and another color (C2).

It takes three named arguments, only the first is required.

1. The color C2 (scalar that is acceptable by the constructor: object, string, ARRAY, HASH).
The name of the argument is with (color is blended with ...).

2. Blend position is a floating point number, which defaults to 0.5.
(blending ratio of 1:1 ). 0 represents here C1 and 1 is pure C2.
Numbers below 0 and above 1 are possible, butlikely to be clamped to
fit inside the color space. Name of the argument is pos.

3. Color space name (default is HSL - all can be seen unter
"COLOR-SPACES" in Graphics::Toolkit::Color::Space::Hub). Name of the argument
is in.

    # a little more silver than $color in the mix
    $color->blend( with => 'silver', pos => 0.6 );
    $color->blend({ with => 'silver', pos => 0.6 });             # works too!
    $blue->blend( with => {H => 240, S =>100, L => 50}, in => 'RGB' ); # teal


construct many interrelated color objects at once.


Creates a gradient (a list of colors that build a transition) between current (C1) and a second, given color (C2) by named argument to.

The only required argument you have to give under the name to is C2. Either as an Graphics::Toolkit::Color object or a scalar (name, hex, HASH or ARRAY), which is acceptable to a "CONSTRUCTOR". This is the same behaviour as in "distance".

An optional argument under the name steps sets the number of colors, which make up the gradient (including C1 and C2). It defaults to 3. Negative numbers will be rectified by "abs". These 3 color objects: C1, C2 and a color in between, which is the same as the result of method "blend".

Another optional argument under the name dynamic is a float number, that defines the position of weight in the color transition from C1 to C2. It defaults to zero which gives you a linear transition, meaning the "distance" between neighbouring colors in the gradient is equal. If $dynamic > 0, the weight is moved toward C1 and vice versa. The greater $dynamic, the slower the color change is in the beginning of the gradient and the faster at the end (C2).

The last optional argument named in defines the color space the changes are computed in. It parallels the argument of the same name from the method "blend" and "distance".

    # we turn to grey
    my @colors = $c->gradient( to => $grey, steps => 5, in => 'RGB');
    # none linear gradient in HSL space :
    @colors = $c1->gradient( to =>[14,10,222], steps => 10, dynamic => 3 );


Creates a set of complementary colors, which will be computed in HSL color space. It accepts 4 optional, named arguments. Complementary colors have a different hue value but same saturation and lightness. Because they form a circle in HSL, they will be called in this paragraph a circle.

If you provide no names (just a single argument), the value is understood as steps. steps is the amount (count) of complementary colors, which defaults to 1 (giving you then THE complementary color). If more than one color is requested, the result will contain the calling object as the first color.

The second optional argument is hue_tilt, in short h, which defaults to zero. When zero, the hue distance between all resulting colors on the circle is the same. When not zero, the hue_tilt gets added (see "add") to THE complementary color. The so computed color divides the circle in a shorter and longer part. Both of these parts will now contain an equal amount of result colors. The distribution will be computed in a way, that there will be a place on the circle where the distance between colors is the highest (let's call it Dmax) and one where it is the lowest (Dmin). The distance between two colors increases or decreases steadily. When hue_tilt is zero, the axis through Dmax and Dmin and the axis through $self and C2 are orthogonal.

The third optional argument saturation_tilt, or short s, which also defaults to zero. If the value differs from zero it gets added the color on Dmax (last paragraph), subtracted on Dmin, changed accordingly in between, so that the circle gets moved in direction Dmin. If you want to move the circle in any other direction you have to give saturation_tilt a HASH reference with 2 keys. First is saturation or s, which is the value as described. Secondly hue or h rotates the direction in which the circle will be moved. Please not, this will not change the position of Dmin and Dmax, because it just defines the angle between the Dmin-Dmax axis and the direction where the circle is moved.

The fourth optional argument is lightness_tilt or lm which works analogously to saturation_tilt. Only difference is that it tilts the circle in the up-down direction, which is in HSL color space lightness.

    my @colors = $c->complement( 4 );    # $self + 3 compementary (square) colors
    my @colors = $c->complement( steps => 3, s => 20, l => -10 );
    my @colors = $c->complement( steps => 3, hue_tilt => -40,
                                     saturation_tilt => {saturation => 300, hue => -50},
                                     lightness_tilt => {l => -10, hue => 30} );


  • Color::Scheme
  • Graphics::ColorUtils
  • Color::Fade
  • Graphics::Color
  • Graphics::ColorObject
  • Color::Calc
  • Convert::Color
  • Color::Similarity


Copyright 2022-2023 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