File Coverage

lib/Graphics/Toolkit/Color/Space/Instance/CIELAB.pm

Criterion	Covered	Total	%
statement	23	23	100.0
branch	4	4	100.0
condition			n/a
subroutine	5	5	100.0
pod	0	2	0.0
total	32	34	94.1

# CIE LAB color space specific code based on XYZ for Illuminant D65 and Observer 2 degree

package Graphics::Toolkit::Color::Space::Instance::CIELAB;
use v5.12;
use warnings;
use Graphics::Toolkit::Color::Space;

my @D65 = (0.95047, 1, 1.08883); # illuminant
my $eta = 0.008856 ;
my $kappa = 903.3;

sub from_xyz {
    my ($xyz) = shift;
    my @xyz = map {($_ > $eta) ? ($_ ** (1/3)) : ((($kappa * $_) + 16) / 116)} @$xyz;
    my $l = (1.16 * $xyz[1]) - 0.16;
    my $a = ($xyz[0] - $xyz[1] + 1) / 2;
    my $b = ($xyz[1] - $xyz[2] + 1) / 2;
    return ([$l, $a, $b]);
}
sub to_xyz {
    my ($lab) = shift;
    my $fy = ($lab->[0] + 0.16) / 1.16;
    my $fx = $fy - 1 + ($lab->[1] * 2);
    my $fz = $fy + 1 - ($lab->[2] * 2);
    my @xyz = map {my $f3 = $_** 3; ($f3 > $eta) ? $f3 : (( 116 * $_ - 16 ) / $kappa) } $fx, $fy, $fz;
    return \@xyz;
}

Graphics::Toolkit::Color::Space->new (
        alias => 'CIELAB',          # space name LAB
         axis => [qw/L* a* b*/],    # short l a b  -  lightness, cyan-orange balance, magenta-green balance
        range => [100, [-500, 500], [-200, 200]],
    precision => 3,
      convert => {XYZ => [\&to_xyz, \&from_xyz]},
);