/ 
Color-RGB-Util-0.595
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/ Color::RGB::Util

NAME

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

VERSION

This document describes version 0.595 of Color::RGB::Util (from Perl distribution Color-RGB-Util), released on 2019-02-13.

SYNOPSIS

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

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 assign_rgb_color("foo");                    # 0b5d33

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

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

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

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

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

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

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_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

DESCRIPTION

FUNCTIONS

None are exported by default, but they are exportable.

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).

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_light_color

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

assign_rgb_dark_color

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

rgb2grayscale

Usage:

my $rgb_gs = rgb2grayscale($rgb);

Convert $rgb to grayscale RGB value.

rgb2sepia

Usage:

my $rgb_sepia = rgb2sepia($rgb);

Convert $rgb to sepia tone RGB value.

reverse_rgb_color

Usage:

my $reversed = reverse_rgb_color($rgb);

Reverse $rgb.

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.

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_diff

Usage:

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

Calculate difference between two RGB colors, using one of several algorithms. The default ("euclidean") simply 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. Another algorithm ("approx1") 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.

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

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".

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.