PHP Color Difference using Delta E CIE 2000
Example Usage (also in example.php):
<?php
include('lib/color_difference.class.php');
$rgb1 = [ 255, 0, 0 ];
$rgb2 = [ 100, 0, 0 ];
$color_difference = (new color_difference())->deltaECIE2000($rgb1, $rgb2);
print $color_difference . chr(10);
?>
Depends on PHP 5.4
$ git clone https://github.com/renasboy/php-color-difference
$ cd php-color-difference
$ php example.php
Formula from www.brucelindbloom.com
Inspired by ruby colorscore and python colormath