Perl snippet: Conversion from CIE 1931 XYZ color space to L* u* v*

XYZtoLuv.pl

#!/usr/bin/perl

use strict;
use warnings;

# Reference X_n ,  Y_n , Z_n default to 1
my ($Xn, $Yn, $Zn);

$Xn = $Yn = $Zn = 1;


# Input values XYZ (as input to file i.e.: "0.7771 0.9185 0.1796")
my $X = shift;
my $Y = shift;
my $Z = shift;

# Case threshold
my $thresh = ($Y/$Yn);

# Compute L* value
my $Ls;
if ($thresh > 0.008856) {
	$Ls = 116 * (($Y/$Yn) ** (1/3)) - 16;
} else {
	$Ls = 903.3 * ($Y/$Yn);
}

# Compute values U' and Un
my $u = (4*$X) / ($X + (15*$Y) + (3*$Z));
my $un = (4*$Xn) / ($Xn + (15*$Yn) + (3*$Zn));

# Compute values V' and Vn
my $v = (9*$Y) / ($X + (15*$Y) + (3*$Z));
my $vn = (9*$Yn) / ($Xn + (15*$Yn) + (3*$Zn));

# Compute u*
my $us = 13 * $Ls * ($u - $un);

# Compute v*
my $vs = 13 * $Ls * ($v - $vn);

print "Result:\nL* = $Ls\nu* = $us\nv* = $vs\n\n";