NAME

       Chart::Color::Value - check, convert and measure color values

SYNOPSIS

           my @names = Chart::Color::Value::all_names();
           my @rgb  = Chart::Color::Value::rgb_from_name('darkblue');
           my @hsl  = Chart::Color::Value::hsl_from_name('darkblue');
           my @hsl2 = Chart::Color::Value::hsl_from_rgb( 5 ,10, 100);
           my $d = Chart::Color::Value::distance_hsl( \@hsl, \@hsl2);

           Chart::Color::Value::add_rgb('lucky', [0, 100, 50]);

DESCRIPTION

       RGB and HSL values of named colors from the X11 and HTML standard and Pantone report.
       Allows also reverse search, storage and conversion of color values.

       This module is supposed to be used by Chart::Color and not directly by the user (for the
       most part). It converts a stored color name into its values (rgb, hsl or both) and back.
       One color can have multiple names.  Also nearby (similar) colors can be searched. Own
       colors can be (none permanently) stored for later reference by name. For this a name has
       to be chosen, that is not already taken. Independently of that can any color be converted
       from rgb to hsl and back.

ROUTINES

   check_rgb
       Return error message if RGB value triplet is not valid (in range).

   check_hsl
       Return error message if HSL value triplet is not valid (in range).

   trim_rgb
       Change RGB triplet to the nearest valid values.

   trim_hsl
       Change HSL triplet to the nearest valid values.

   hsl_from_rgb
       Converting an rgb value triplet into the corresponding hsl

       Red, Green and Blue are integer in 0 .. 255.  Hue is an integer between 0 .. 359 (hue) and
       saturation and lightness are 0 .. 100 (percentage).  A hue of 360 and 0 (degree in a
       cylindrical coordinate system) is considered to be the same, this modul deals only with
       the ladder.

   rgb_from_hsl
       Converting an hsl value triplet into the corresponding rgb (see rgb_from_name and
       hsl_from_name). Please not that back and forth conversion can lead to drifting results due
       to rounding.

           my @rgb = Chart::Color::Value::rgb_from_hsl(0, 90, 50);
           my @rgb = Chart::Color::Value::rgb_from_hsl([0, 90, 50]); # works too
           # for real (none integer results), any none zero value works as second arg
           my @rgb = Chart::Color::Value::rgb_from_hsl([0, 90, 50], 'real');

   distance_rgb
       Distance in (linear) rgb color space between two coordinates.

           my $d = Chart::Color::Value::distance_rgb([1,1,1], [2,2,2]);  # approx 1.7

   distance_hsl
       Distance in (cylindrical) hsl color space between two coordinates.

           my $d = Chart::Color::Value::distance_rgb([1,1,1], [356, 3, 2]); # approx 6

COPYRIGHT & LICENSE

       Copyright 2022 Herbert Breunung.

       This program is free software; you can redistribute it and/or modify it under same terms
       as Perl itself.

AUTHOR

       Herbert Breunung, <lichtkind@cpan.org>