PHP function, returns either black or white hex value to contrast with a given hex colour.

get_contrasting_colour.php

/*
	Original code from http://www.webmasterworld.com/forum88/9769.htm, tweaked to accomodate for shorthand hex (#fff)
*/

function get_contrasting_colour($hex) {
	$hex = str_replace('#', '', $hex);
	$l=2;
	if(strlen($hex==3)){$l=1;}
	$c_r = hexdec(substr($hex, 0, $l));
	$c_g = hexdec(substr($hex, 2, $l));
	$c_b = hexdec(substr($hex, 4, $l));
	$b = (($c_r * 299) + ($c_g * 587) + ($c_b * 114)) / 1000;
	if($b>130){
		return '#000';
	}else{
		return '#fff';
	}
}