Php library to convert between sRGB, XYZ, and Lab color spaces, and calculate various color distance metrics (delta E). Currently CIE76 and CIE94 are implemented, but I plan to implement more.
use Danmichaelo\Coma\ColorDistance,
Danmichaelo\Coma\sRGB;
$color1 = new sRGB(1, 5, 250);
$color2 = new sRGB(0, 0, 208);
$cd = new ColorDistance;
$cie94 = $cd->cie94($color1, $color2);
echo 'The CIE94 ∆E is ' . $cie94 . ' between ' . $color1->toHex() . ' and ' . $color2->toHex() . '.';