<div class="jb51code">
<pre class="brush:php;">
function hex2rgb($hex) {
$color = str_replace('#','',$hex);
$rgb = array('r' => hexdec(substr($color,2)),'g' => hexdec(substr($color,2,'b' => hexdec(substr($color,4,2)));
return $rgb;
} // www.jb51.cc

function rgb2cmyk($var1,$g=0,$b=0) {
if (is_array($var1)) {
$r = $var1['r'];
$g = $var1['g'];
$b = $var1['b'];
} else {
$r=$var1;
}
$cyan = 255 - $r;
$magenta = 255 - $g;
$yellow = 255 - $b;
$black = min($cyan,$magenta,$yellow);
$cyan = @(($cyan - $black) / (255 - $black)) 255;
$magenta = @(($magenta - $black) / (255 - $black)) 255;
$yellow = @(($yellow - $black) / (255 - $black)) * 255;
return array('c' => $cyan / 255,'m' => $magenta / 255,'y' => $yellow / 255,'k' => $black / 255);
}

$color=rgb2cmyk(hex2rgb('#FF0000'));