NAME
Graphics::Toolkit::Color - calculate color (sets), IO many spaces and formats
SYNOPSIS
use Graphics::Toolkit::Color qw/color is_in_gamut/;
my $red = Graphics::Toolkit::Color->new('red'); # create color object
say $red->add_value( 'blue' => 255 )->name; # red + blue = 'magenta'
my @blue = color( 0, 0, 255)->values('HSL'); # 240, 100, 50 = blue
if (is_in_gamut('oklab(14, -106, 3)')) { .. # check if valid
$red->mix( to => [HSL => 0,0,80], amount => 10); # mix red with a little grey
$red->gradient( to => '#0000FF', steps => 10); # 10 colors from red to blue
my @base_triadic = $red->complement( 3 ); # get fitting red green and blue
my @reds = $red->cluster( r => 1.1, min_d => 1 );# 13 shades of redDESCRIPTION
Graphics::Toolkit::Color, for short GTC, is the top level API of this release and the only package a regular user should be concerned with. Its main purpose is the creation of related colors or sets of them, such as gradients, complements and more. But if you want to convert, quantize, round or reformat color definitions, it can be helpful too.
GTC are read only, one color representing objects with no additional dependencies. Create them in many different ways (see "CONSTRUCTOR"). Access its values via methods from section "GETTER". Measure differences with the "distance" method. "SINGLE-COLOR" methods create one new object that is related to the current one and "COLOR-SETS" methods will create a group of colors, that are not only related to the current color but also have relations between each other. Error messages will appear as return values instead of the expected result.
While this module can understand and output color values for many color spaces, 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 (nonlinear standard RGB). Humans access colors on hardware level (eye) in RGB, on cognition level in HSL or LAB (brain) and on cultural level (language) with names. With all these options available you can express easily and intuitively with which color to start. And plenty of functions with lots of options help you to arrive at the desired color (palette) quickly.
CONSTRUCTOR
There are many ways to create a color object. In short you can either use the name of a constant (see "name") or provide values, which are coordinates in one of several color spaces. The latter are also understood in many formats. From now on any input that the constructor method new accepts, is called a color definition.
new({ r => $r, g => $g, b => $b })
Most clear, flexible and longest input format: a hash with long or short axis names as keys with fitting values. This can be red, green and blue or r, g and b or names from any other color space. Upper or lower case doesn't matter.
my $red = Graphics::Toolkit::Color->new( r => 255, g => 0, b => 0 );
my $red = Graphics::Toolkit::Color->new({r => 255, g => 0, b => 0}); # works too
... ->new( Red => 255, Green => 0, Blue => 0); # also fine
... ->new( Hue => 0, Saturation => 100, Lightness => 50 ); # same color
... ->new( Hue => 0, whiteness => 0, blackness => 0 ); # still the samenew( [$r, $g, $b] )
takes a triplet of integer RGB values (red, green and blue : 0 .. 255). They can, but don't have to be put into an ARRAY reference (square brackets). If you want to define a color by values from another color space, you have to prepend the values with the name of a supported color space. Out of range (gamut) values will be corrected (clamped).
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 ARRAY syntax
my $red = Graphics::Toolkit::Color->new( RGB => 255, 0, 0 ); # with fat comma
my $red = Graphics::Toolkit::Color->new([ RGB => 255, 0, 0]); # and brackets
my $red = Graphics::Toolkit::Color->new( RGB => [255, 0, 0]); # separate name and values
my $red = Graphics::Toolkit::Color->new( YUV => .299,-0.168736, .5); # same color in YUVnew('rgb($r,$g,$b)')
String format that is supported by CSS (css_string format): it starts with the case insensitive color space name (lower case is default), followed by the (optionally) comma separated values in round braces. The value suffixes that are defined by the color space ('%' in case of HSV) are optional.
my $red = Graphics::Toolkit::Color->new( 'rgb(255 0 0)' ); # comma optional
my $blue = Graphics::Toolkit::Color->new( 'hsv(240, 100%, 100%)' );
my $blue = Graphics::Toolkit::Color->new( 'hsv(240, 100, 100)' ); # works toonew('rgb: $r, $g, $b')
String format named_string (good for serialisation) that maximizes readability. Here are commas not optional, but space name is still case insensitive.
my $red = Graphics::Toolkit::Color->new( 'rgb: 255, 0, 0' );
my $blue = Graphics::Toolkit::Color->new( 'HSV: 240, 100, 100' );new('#rgb')
Color definitions in hexadecimal format as widely used in the web, are also acceptable (RGB only).
my $color = Graphics::Toolkit::Color->new('#FF0000');
my $color = Graphics::Toolkit::Color->new('#f00'); # short versionnew('name')
Get a color object by providing a name from the X11, HTML (CSS) or SVG scheme 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 here .
my $color = Graphics::Toolkit::Color->new('Emerald');
my @names = Graphics::Toolkit::Color::Name::all(); # select from thesenew('scheme:color')
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 or with Bundle::Graphics::ColorNames. See all scheme names here . The color name will be normalized as above.
my $color = Graphics::Toolkit::Color->new('SVG:green');
my @schemes = Graphics::ColorNames::all_schemes(); # look up the installedcolor
If writing
Graphics::Toolkit::Color->new( ...);is too much typing work for you or takes up to much space in the code file, import the subroutine color, which accepts all the same arguments as new.
use Graphics::Toolkit::Color qw/color/;
my $green = color('green');
my $darkblue = color([20, 20, 250]);GETTER
giving access to different parts of the objects data.
values
Returns the numeric values of the color, held by the object. The method accepts five optional, named arguments: "in" (color space), as (format), "range", precision and suffix. In most cases, only the first one is needed.
When given no arguments, the method returns a list with the integer values: red, green and blue in 0 .. 255 range, since RGB is the default color space of this module.
If one positional argument is provided, the values get converted into the color space of the given name. The same is done when using the named argument "in" (full explanation behind the link). The named argument "range" is also explained in its own section. Please note you have to use the range argument only, if you like to deviate from the value ranges defined by the chosen color space.
The maybe most characteristic argument for this method is as, which enables all the same numeric formats the constructor method new accepts. GTC is built with the design principle of total serialisation. This means: every contructor input format can be reproduced by a getter method and vice versa. These formats are: 'list' (default), C'<named_array'>, 'hash', 'char_hash', 'named_string', 'css_string', 'array' (RGB only) and 'hex_string' (RGB only). The remaining two. name and full:name are produce by the method "name". Format names are case insensitive. For more explanations, please see: formats section in GTC::Space::Hub.
precision is a more exotic argument, but sometimes you need to escape the numeric precision, set by a color spaces definition. For instance LAB values will have maximally three decimals, no matter how precise the input was. In case you prefer 4 decimals, just use precision => 4. A zero means no decimals and -1 stands for maximal precision - which may spit out more decimals than you prefer. Different precisions per axis are possible via an ARRAY ref: precision => [1,2,3].
In the same way you can atach a little strings per value by using the suffix argument. Normally these are percentage signs but in some spaces, where they appear by default you can surpress them by adding suffix => '',
$blue->values(); # 0, 0, 255
$blue->values( in => 'RGB', as => 'list'); # 0, 0, 255 # explicit arguments
$blue->values( as => 'array'); # [0, 0, 255] - RGB only
$blue->values( in => 'RGB', as => 'named_array'); # ['RGB', 0, 0, 255]
$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 => 'named_string'); # 'rgb: 0, 0, 255'
$blue->values( in => 'RGB', as => 'css_string'); # 'rgb( 0, 0, 255)'
$blue->values( as => 'hex_string'); # '#0000ff' - RGB only
$blue->values( range => 2**16 ); # 0, 0, 65536
$blue->values('HSL'); # 240, 100, 50
$blue->values( in => 'HSL',suffix => ['', '%','%']); # 240, '100%', '50%'
$blue->values( in => 'HSB', as => 'hash')->{'hue'}; # 240
($blue->values( 'HSB'))[0]; # 240
$blue->values( in => 'XYZ', range => 1, precision => 2);# normalized, 2 decimals max.name
Returns the normalized name string (lower case, without '_') that represents the RGB values of this color in the default color scheme, which is X11 + HTML (SVG) + Pantone report (see all names). These are the same which can be used with "new('name')".
Alternatively you may provide named arguments or one positional argument, which is the same as the named argument from. That required a name of a color schemes, as listed here. You also can submit a list thereof inside a ARRRAY ref which also dictates the order of resulting color names. Please note that all color schemes, except the default one, depend on external modules, which have to be installed separately or via Bundle::Graphics::ColorNames. If you try to use a scheme from a not installed module your will get an error message instead of a color name. You can also create your custom color naming scheme via Graphics::Toolkit::Color::Name::Scheme.
The second named argument is all, which needs to be a perly boolean. It defaults to false. But if set to 1, you will get a list of all names that are associated with the current values. There will be no duplicates, when several schemes are searched.
A third named argument is full - also needing a perly boolean that defaults to false. When set true (1), the schema name becomes part of the returned color name as in 'SVG:red'. These full names are also accepted by the constructor.
The fourth named argument is distance, which means the same thing as in "distance" and it defaults to zero. It is most useful in combinataion with all to get all color names that are within a certain distance.
$blue->name(); # 'blue'
$blue->name('SVG'); # 'blue'
$blue->name( from => [qw/CSS X/], all => 1); # 'blue', 'blue1'
$blue->name( from => 'CSS', full => 1); # 'CSS:blue'
$blue->name( distance => 3, all => 1) ; # all names within the distanceclosest_name
Returns in scalar context a color name, which has the shortest "distance" in RGB to the current color. In list context, you get additionally the just mentioned distance as a second return value. This method works almost identically as method "name", but guarantees a none empty result, unless invoking a unusually empty color scheme.
All arguments work as mentioned above, only here is no distance argument. The only difference is (due to the second return value), multiple names (when requested) have to come in the form of an ARRAY as the first return value.
my $name = $red_like->closest_name; # closest name in default scheme
my $name = $red_like->closest_name('HTML'); # closest HTML constant
($red_name, $distance) = $red_like->closest_name( from => 'Pantone', all => 1 );distance
Is a floating point number that measures the Euclidean distance between two colors, which represent two points in a color space. One color is the calling object itself and the second one has to be provided as either the only argument or the named argument "to", which is the only required one.
The distance is measured in RGB color space unless told otherwise by the argument "in". Please use the OKLAB (better) or CIELUV space, if you are interested in getting a result that matches the human perception.
The third argument is named select. It's useful if you want to regard only certain dimensions (axis - long and short axis names are accepted). For instance if you want to know only the difference in brightness between two colors, you type select => 'lightness' or select => 'l'. This naturally works only if you did also choose HSL as a color space or something similar that has a lightness axis like LAB or OKLAB. The select argument accepts a string or an ARRAY with several axis names, which can also repeat. For instance there is a formula to compute distances in RGB that weights the squared value delta's: $distance = sqrt( 3 * delta_red**2 + 4 * delta_green**2 + 2 * delta_blue**2). You can recreate that formula by typing select => [qw/ r r r g g g g b b/]
The last argument is named "range", which can change the result drasticly.
my $d = $blue->distance( 'lapisblue' ); # how close is blue to lapis?
$d = $blue->distance( to => 'airyblue', select => 'b'); # have they the same amount of blue?
$d = $color->distance( to => $c2, in => 'HSL', select => 'hue' ); # same hue?
$d = $color->distance( to => $c2, range => 'normal' ); # distance with values in 0 .. 1 range
$d = $color->distance( to => $c2, select => [qw/r g b b/]); # double the weight of blue value differencesis_in_gamut
Takes any here described color definition and returns a perlish pseudo boolean (zero or one). It will tell you if the color is within the gamut, of the color space, the color was defined in. Or in simpler terms: are the color values within the accepted ranges? Some spaces exclude certain value combinations. This is the way to ensure you got a valid color definition. Since the GTC "CONSTRUCTOR" clamps out of shape values, and forces them to be in gamut - this method is only needed to ensure that there is nothing to clamp and the constructor did not change any value.
If it is too clumsy for you to use an existing color object to check if another color is valid: use th importable routine with the same name.
if ($color->is_in_gamut([ RGB => 255, 0, 0])){ # it has to be ..
use Graphics::Toolkit::Color qw/is_in_gamut/;
if (is_in_gamut('rgb: 0, 0, 300')){ # too much blue ..SINGLE COLOR
These methods generate one new color object that is related to the calling object (invocant). You might expect that methods like set_value change the values of the invocant, but GTC objects are as mentioned in the "DESCRIPTION" read only. That supports a more functional programming style as well as method stacking like:
$color->add_value( saturation => 5)->invert->mix( to => 'green');set_value
Creates a new GTC color object that shares some values with the current one, but differs in others. The altered values are provided as absoltue numbers. If the resulting color will be outside of the given color space, the values will be clamped so it will become a regular color of that space.
The axis of all supported color spaces have long and short names. For instance HSL has hue, sturation and lightness. The short equivalents are h, s and l. This method accepts these axis names as named arguments and disregards if characters are written upper or lower case. This method can not work, if you mix axis names from different spaces or choose one axis more than once. One solvable issue is when axis in different spaces have the same name. For instance HSL and HSV have a saturation axis. To disambiguate you can add the named argument "in".
my $blue = $black->set_value( blue => 255 ); # same as #0000ff
my $pale_blue = $blue->set_value( saturation => 50 ); # ->( s => 50) works too
my $color = $blue->set_value( saturation => 50, in => 'HSV' ); # previous was HSLadd_value
Creates a new GTC color object that shares some values with the current one, but differs in others. The altered values are provided relative to the current ones. The rest works as described in "set_value". This method was mainly created to get lighter, darker or more saturated colors by using it like:
my $blue = Graphics::Toolkit::Color->new('blue');
my $darkblue = $blue->add_value( Lightness => -25 ); # get a darker tone
my $blue2 = $blue->add_value( blue => 10 ); # bluer than blue ?
my $blue3 = $blue->add_value( l => 10, in => 'LAB' ); # lighter color according CIELABapply
Creates a new GTC color object with recalculated values. Each calculation is triggered by one named argument and currently is only one possible. gamma triggers a gamma correction which can be reversed with the inverse argument. Use an ARRAY ref to apply each color value with a different gamma. The argument "in" determines in which space the carlculation takes place:
my $linear_blue = $blue->apply( gamma => 2.2 ); # is same the as :
my $linear_blue = $blue->apply( gamma => [2.2, 2.2, 2.2], in => 'RGB' );mix
Create a new GTC object, that has the average values between the calling object and another color (or several colors). It accepts three named arguments: "to", amount and "in", but only the first one is required and can be also provided as the only positional argument.
The "to" argument works like in other methods, with the exception that it also accepts an ARRAY ref (square brackets) with several color definitions or GTC color objects.
Per default mix computes a 50-50 (1:1) mix between all involved colors. In order to change that, employ the amount argument, which is the share the mixed in color(s) get, counted in percentage. The remaining percentage to 100 is the share of the color, held by the caller object. This would be naturally nothing, if the amount is greater than hundret. When mixing more than two colors at once, amount accpets also an ARRAY of share values that will applied in the same order as the colors of the to argument. Their sum can reach easily values greater than 100. In that case again the calling object gets no share. If the amount-sum is greater than 100, than the amounts will be recalculated, keeping the ratios but leaving out the calling color. If you mix mor than two colors, but provide only one scalar amout value, then will be applied to all mixed in colors.
$blue->mix( $silver ); # 50% silver, 50% blue
$blue->mix( to => 'silver', amount => 60 ); # 60% silver, 40% blue
$blue->mix( to => [qw/silver green/], amount => [10, 20]); # 10% silver, 20% green, 70% blue
$blue->mix( to => [qw/silver green/], amount => [30, 90]); # 25% silver, 75% green, 0% blue
$blue->mix( to => [qw/silver green/], amount => 30); # 30% silver, 30% green, 40% blue
$blue->mix( to => [qw/silver green/] ); # 33% silver, 33% green, 33% blue
$blue->mix( to => {H => 120, S =>100, L => 50}, in => 'HSV' ); # teal = 50% green, 50% blueinvert
Computes the a new color object, where all values are inverted according to the ranges of the chosen color space (see "in"). It takes only one optional, positional argument, a space name.
my $black = $white->invert(); # to state the obvious
my $blue = $yellow->invert( 'LUV' ); # invert in LUV space
$yellow->invert( in => 'LUV' ); # would work tooCOLOR SETS
construct several interrelated color objects at once.
complement
Creates a set of complementary colors (GTC objects), which will be computed in HSL color space. The method accepts three optional, named arguments: steps and tilt and target. But if none are provided, THE (one) complementary color will be produced.
One singular, positional argument defines the number of produced colors, same as the named argument steps would have. If you want to get 'triadic' colors, choose 3 as an argument for steps - 4 would get you the 'tetradic' colors, .... and so on. The given color is always the last in the row of produced complementary colors.
If you need split-complementary colors, just use the tilt argument, which defaults to zero. Without any tilt, complementary colors are equally distanced dots on a horizontal circle around the vertical, central column in HSL space. In other words: complementary colors have all the same 'saturation' (distance from the column) and 'lightness' (height). They differ only in 'hue' (position on the circle). The given color and its (THE) complement sit on opposite sides of the circle. The greater the tilt amount, the more these colors (minus the given one) will move on the circle toward THE complement and vice versa. What is traditionally meant by split-complementary colors you will get here with a tilt factor of around 3.42 and three steps or a tilt of 1.585 and four steps (depending on if you need THE complement also in your set).
To get an even greater variety of complementary colors, you can use target argument and move around THE complement and thus shape the circle in all three directions. hue (or h) values move it circularly saturation (or s) move it away or negative values toward the central column and lightness (or l) move it up and down.
my @colors = $c->complement( 4 ); # 'tetradic' colors
my @colors = $c->complement( steps => 4, tilt => 4 ); # split-complementary colors
my @colors = $c->complement( steps => 3, tilt => { move => 2, target => {l => -10}} );
my @colors = $c->complement( steps => 3, tilt => { move => 2,
target => { h => 20, s=> -5, l => -10 } });gradient
Creates a gradient (a list of color objects that build a transition) between the current color held by the object and a second color, provided by the named argument "to", which is required. Optionally to accepts an ARRAY ref (square braces) with a list of colors in order to create the most fancy, custom and nonlinear gradients.
Also required is the named argument steps, which is the gradient length or count of colors, which are part of this gradient. Included in there are the start color (given by this object) and end color (given with to).
The optional, floating point valued argument tilt makes the gradient skewed toward one or the other end. Default is zero, which results in a linear, uniform transition between start and stop. Greater values of the argument let the color change rate start small, steadily getting bigger. Negative values work vice versa. The bigger the absolute numeric value the bigger the effect. Please have in mind that values over 2 result is a very strong tilt.
Optional is the named argument "in" (color space - details behind link). Tip: use oklab and cieluv spaces for visually smooth gradients.
# we turn to grey
my @colors = $c->gradient( to => $grey, steps => 5);
# none linear gradient in HSL space :
@colors = $c1->gradient( to =>[14,10,222], steps => 10, tilt => 1, in => 'HSL' );
@colors = $c1->gradient( to =>['blue', 'brown', {h => 30, s => 44, l => 50}] );cluster
Computes a set of colors that are all similar but not the same. The method accepts three named arguments: radius, distance and "in", of which the first two are required.
The produced colors form a ball or cuboid in a color space around the given color, depending on what the argument radius got. If it is a single number, it will be a ball with the given radius. If it is an ARRAY of values you get the a cuboid with the given dimensions.
The minimal distance between any two colors of a cluster is set by the minimal_distance argument, which is computed the same way as the method "distance", in has a short alias min_d. In a cuboid shaped cluster- the colors will form a cubic grid - inside the ball shaped cluster they form a cuboctahedral grid, which is packed tighter, but still obeys the minimal distance.
my @blues = $blue->cluster( radius => 4, minimal_distance => 0.3 );
my @c = $color->cluster( r => [2,2,3], min_d => 0.4, in => YUV );ARGUMENTS
Some named arguments of the above listed methods reappear in several methods. Thus they are explained here once. Please note that you must NOT wrap the named args in curly braces (HASH ref).
in
The named argument in expects the name of a color space as listed here. The default color space in this module is RGB. Depending on the chosen space, the results of all methods can be very different, since colors are arranged there very differently and have different distances to each other. Some colors might not even exist in some spaces.
range
Every color space comes with range definitions for its values. For instance red, green and blue in RGB go usually from zero to 255 (0..255). In order to change that, many methods accept the named argument range. When only one interger value provided, it changes the upper bound on all three axis and as lower bound is assumed zero. Let's say you need RGB16 values with a range of 0 .. 65536, then you type range => 65536 or range => 2**16.
If you provide an ARRAY ref you can change the upper bounds of all axis individually and in order to change even the lower boundaries, use ARRAY refs even inside that. For instance in HSL the hue is normally 0 .. 359 and the other two axis are 0 .. 100. In order to set hue to -100 .. 100 but keep the other two untouched you would have to insert: range => [[-100,100],100,100].
to
This argument receives a second or target color. It may come in form of another GTC object or a color definition that is acceptable to the constructor. But it has to be a scalar (string or (HASH) reference), not a value list or hash.
SEE ALSO
ACKNOWLEDGEMENT
These people contributed by providing patches, bug reports and useful comments:
Petr Pisar (ppisar)
Slaven Rezic (srezic)
Gabor Szabo (szabgab)
Gene Boggs (GENE)
Stefan Reddig (sreagle)
AUTHOR
Herbert Breunung, <lichtkind@cpan.org>
COPYRIGHT
Copyright 2022-2026 Herbert Breunung.
LICENSE
This program is free software; you can redistribute it and/or modify it under the same terms as Perl itself.