view release on metacpan or  search on metacpan

README  view on Meta::CPAN

  rgb2sepia
    Usage:

     my $rgb_sepia = rgb2sepia($rgb);

    Convert $rgb to sepia tone RGB value.

    See also rgb2grayscale.

  rgb_closest_to
    Usage:

     my $colorname = rgb_closest_to( [ \%opts , ] $color);

    Return the primary color $color is closest to. Options:

    *   colors

        A hash of color names and RGB values. If unspecified, the default
        is:

         {
          black   => "000000",
          blue    => "0000ff",
          brown   => "663333",
          cyan    => "00ffff", # a.k.a. aqua
          green   => "00ff00",
          grey    => "808080",
          magenta => "ff00ff", # a.k.a. fuchsia
          orange  => "ff8000",
          pink    => "ffcccc",
          purple  => "800080", # a.k.a. violet
          red     => "ff0000",
          white   => "ffffff",
          yellow  => "ffff00",
         }

  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, described in [1] as "a low cost approximation" and
        "a combination both weighted Euclidean distance functions, where the
        weight factors depend on how big the 'red' component of the colour
        is" with "results that are very close to L*u*v" and "a more stable
        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.

    TODO: redmean low-cost approximation, CMC l:c.

    For more about color difference, try reading
    <https://en.wikipedia.org/wiki/Color_difference>.

    [1] https://www.compuphase.com/cmetric.htm

    See also rgb_distance.

  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.

    See also rgb_diff.

  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".

    See also "rgb_is_light".

  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".

    See also "rgb_is_dark".

  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.

    See also mix_2_rgb_colors, mix_rgb_colors.

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>.

SEE ALSO
    Color::ANSI::Util

AUTHOR
    perlancar <perlancar@cpan.org>

CONTRIBUTOR
    Steven Haryanto <stevenharyanto@gmail.com>

CONTRIBUTING
    To contribute, you can send patches by email/via RT, or send pull
    requests on GitHub.

    Most of the time, you don't need to build the distribution yourself. You
    can simply modify the code, then test via:

     % prove -l

    If you want to build the distribution (e.g. to try to install it locally
    on your system), you can install Dist::Zilla,
    Dist::Zilla::PluginBundle::Author::PERLANCAR,
    Pod::Weaver::PluginBundle::Author::PERLANCAR, and sometimes one or two
    other Dist::Zilla- and/or Pod::Weaver plugins. Any additional steps
    required beyond that are considered a bug and can be reported to me.

COPYRIGHT AND LICENSE
    This software is copyright (c) 2023, 2021, 2020, 2019, 2018, 2015, 2014,
    2013 by perlancar <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.

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