NAME

Color::RGB::Util - Utilities related to RGB colors

VERSION

This document describes version 0.599 of Color::RGB::Util (from Perl distribution Color-RGB-Util), released on 2019-08-20.

SYNOPSIS

 use Color::RGB::Util qw(
     assign_rgb_color
     assign_rgb_dark_color
     assign_rgb_light_color
     int2rgb
     mix_2_rgb_colors
     mix_rgb_colors
     rand_rgb_color
     rand_rgb_colors
     reverse_rgb_color
     rgb2grayscale
     rgb2int
     rgb2sepia
     rgb_diff
     rgb_distance
     rgb_is_dark
     rgb_is_light
     rgb_luminance
     tint_rgb_color
 );

 say assign_rgb_color("foo");                    # 0b5d33
 say assign_rgb_dark_color("foo");               # 0b5d33
 say assign_rgb_light_color("foo");              # 85ae99

 say int2rgb(0xffffff);                          # ffffff

 say mix_2_rgb_colors('#ff0000', '#ffffff');     # pink (red + white)
 say mix_2_rgb_colors('ff0000', 'ffffff', 0.75); # pink with a whiter shade

 say mix_rgb_colors('ff0000', 1, 'ffffff', 1);   # pink (red + white 1 : 1)
 say mix_rgb_colors('ff0000', 1, 'ffffff', 3);   # pink with a whiter shade (red + white 1 : 3)
 say mix_rgb_colors('ff0000', 1, 'ffffff', 1, '0000ff', 0.5);   # bluish pink

 say rand_rgb_color();
 say rand_rgb_color('000000', '333333');         # limit range

 say rand_rgb_colors(
       {light_color => 1, avoid_colors=>[qw/ffffff ffcc00 ff00cc/],
       3);                                       # ("e9f3d7", "e0bbcc", "63f88c")

 say reverse_rgb_color('0033CC');                # => ffcc33

 say rgb2grayscale('0033CC');                    # => 555555

 say rgb2int("ffffff");                          # 16777215 (which is 0xffffff)

 say rgb2sepia('0033CC');                        # => 4d4535

 say rgb_distance('000000', '000000')            # => 0
 say rgb_distance('01f000', '04f400')            # => 5
 say rgb_distance('ffff00', 'ffffff')            # => 255

 say rgb_diff('000000', '000000');               # => 0
 say rgb_diff('01f000', '04f400');               # => 5
 say rgb_diff('ffff00', 'ffffff');               # => 255
 say rgb_diff('000000', '000000', 'approx1');    # => 0
 say rgb_diff('01f000', '04f400', 'approx1');    # => 9.06
 say rgb_diff('ffff00', 'ffffff', 'approx1');    # => 360.98

 say rgb_is_dark('404040');                      # => 1
 say rgb_is_dark('a0a0a0');                      # => 0
 say rgb_is_light('404040');                     # => 0
 say rgb_is_light('a0a0a0');                     # => 1

 say rgb_luminance('d090aa');                    # => ffcc33

 say tint_rgb_color('#ff8800', '#0033cc');       # => b36e3c

DESCRIPTION

FUNCTIONS

None are exported by default, but they are exportable.

assign_rgb_color

Usage:

 my $rgb = assign_rgb_color($str);

Map a string to an RGB color. This is done by producing SHA-1 digest (160bit, 20 bytes) of the string, then taking the first, 10th, and last byte to become the RGB color.

assign_rgb_dark_color

Like "assign_rgb_color" except that it will make sure the assigned color is dark.

assign_rgb_light_color

Like "assign_rgb_color" except that it will make sure the assigned color is light.

int2rgb

Usage:

 my $rgb = int2rgb(0xffffff); # => ffffff

Convert integer to RGB string.

mix_2_rgb_colors

Usage:

 my $mixed_rgb = mix_2_rgb_colors($rgb1, $rgb2, $pct);

Mix 2 RGB colors. $pct is a number between 0 and 1, by default 0.5 (halfway), the closer to 1 the closer the resulting color to $rgb2.

mix_rgb_colors

Usage:

 my $mixed_rgb = mix_rgb_colors($color1, $weight1, $color2, $weight2, ...);

Mix several RGB colors.

rand_rgb_color

Usage:

 my $rgb = rand_rgb_color([ $low_limit [ , $high_limit ] ]);

Generate a random RGB color. You can specify the limit. Otherwise, they default to the full range (000000 to ffffff).

rand_rgb_colors

Usage:

 my @rgbs = rand_rgb_colors([ \%opts ], $num=1);

Produce $num random RGB colors, with some options. Will make reasonable attempt to make the colors different from one another.

Known options:

  • light_color

    Boolean, default true. By default, this function will create light RGB colors, assuming the background color is dark, which is often the case in terminal. If this option is set to false, will create dark colors instead, If this option is set to undef, will create both dark and light colors.

  • avoid_colors

    Arrayref or hashref. List of colors to be avoided. You can put, for example, colors that you've already assigned/picked for your palette and don't want to use again.

  • max_attempts

    Uint, default 1000. Number of attempts to try generating the next random color if the generated color is rejected because it is light/dark, or because it's in avoid_colors.

    When the number of attempts has been exceeded, the generated color is used anyway.

reverse_rgb_color

Usage:

 my $reversed = reverse_rgb_color($rgb);

Reverse $rgb.

rgb2grayscale

Usage:

 my $rgb_gs = rgb2grayscale($rgb);

Convert $rgb to grayscale RGB value.

rgb2hsl

Usage:

 my $hsl = rgb2hsl($rgb); # example: "0 1 0.5"

Convert RGB (0-255) to HSL. The result is a space-separated H, S, L values.

rgb2hsv

Usage:

 my $hsv = rgb2hsv($rgb); # example: "0 1 255"

Convert RGB (0-255) to HSV. The result is a space-separated H, S, V values.

rgb2int

Usage:

 my $int = rgb2int("ffffff"); # => 16777216, which is 0xffffff

Convert RGB string to integer.

rgb2sepia

Usage:

 my $rgb_sepia = rgb2sepia($rgb);

Convert $rgb to sepia tone RGB value.

rgb_diff

Usage:

 my $dist = rgb_diff($rgb1, $rgb2[ , $algo ])

Calculate difference between two RGB colors, using one of several algorithms.

  • euclidean

    The default. It calculates the distance as:

     ( (R1-R2)**2 + (G1-G2)**2 + (B1-B2)**2 )**0.5

    which is the same as what "rgb_distance"() would produce.

  • approx1

    This algorithm uses the following formula:

     ( 2*(R1-R2)**2 + 4*(G1-G2)**2 + 3*(B1-B2)**2 + Rm*((R1-R2)**2 - (B1-B2)**2)/256 )**0.5

    where, Rm or "R mean" is (R1+R2)/2.

  • approx2

    Like approx1, but uses this formula:

     ( 2*(R1-R2)**2 + 4*(G1-G2)**2 + 3*(B1-B2)**2 )**0.5  # if Rm < 128
     ( 3*(R1-R2)**2 + 4*(G1-G2)**2 + 2*(B1-B2)**2 )**0.5  # otherwise
  • hsv_euclidean

    Convert the RGB values to HSV, then calculate the HSV distance. Please see source code for details.

  • hsv_hue1

    Like hsv_euclidean but puts more emphasis on hue difference. This algorithm is used, for example, by Color::ANSI::Util when mapping RGB 24bit color to the "closest" the ANSI 256-color or 16-color. This algorithm tends to choose the hued colors instead of favoring to fallback on white/gray, which is more preferred.

For more details about color difference, refer to https://en.wikipedia.org/wiki/Color_difference.

rgb_distance

Usage:

 my $dist = rgb_distance($rgb1, $rgb2)

Calculate the euclidean RGB distance, using this formula:

 ( (R1-R2)**2 + (G1-G2)**2 + (B1-B2)**2 )**0.5

For example, the distance between "000000" and "ffffff" is ~441.67, while the distance between "ffff00" and "ffffff" is 255.

rgb_is_dark

Usage:

 my $is_dark = rgb_is_dark($rgb)

Return true if $rgb is a "dark" color, which is determined by checking if the RGB distance to "000000" is smaller than to "ffffff".

rgb_is_light

Usage:

 my $is_light = rgb_is_light($rgb)

Return true if $rgb is a "light" color, which is determined by checking if the RGB distance to "000000" is larger than to "ffffff".

rgb_luminance

Usage:

 my $luminance = rgb_luminance($rgb);

Calculate standard/objective luminance from RGB value using this formula:

 (0.2126*R) + (0.7152*G) + (0.0722*B)

where R, G, and B range from 0 to 1. Return a number from 0 to 1.

tint_rgb_color

Usage:

 my $new_rgb = tint_rgb_color($rgb, $tint_rgb, $pct)

Tint $rgb with $tint_rgb. $pct is by default 0.5. It is similar to mixing, but the less luminance the color is the less it is tinted with the tint color. This has the effect of black color still being black instead of becoming tinted.

HOMEPAGE

Please visit the project's homepage at https://metacpan.org/release/Color-RGB-Util.

SOURCE

Source repository is at https://github.com/perlancar/perl-Color-RGB-Util.

BUGS

Please report any bugs or feature requests on the bugtracker website https://rt.cpan.org/Public/Dist/Display.html?Name=Color-RGB-Util

When submitting a bug or request, please include a test-file or a patch to an existing test-file that illustrates the bug or desired feature.

SEE ALSO

Color::ANSI::Util

AUTHOR

perlancar <perlancar@cpan.org>

COPYRIGHT AND LICENSE

This software is copyright (c) 2019, 2018, 2015, 2014, 2013 by perlancar@cpan.org.

This is free software; you can redistribute it and/or modify it under the same terms as the Perl 5 programming language system itself.