A PHP toolkit for converting between Hex, RGB, and HSL colors. Also can calculate hue shifts, monochromatic schemes, etc.
First initialize a ColorTool object:
$color = new ColorTool();
Then use one of the following three functions to give it a value:
$color->set_hex("#000000");
$color->set_rgb(array($r, $g, $b));
$color->set_hsl(array($h, $s, $l));
View index.php to see some examples.