Sorry to re-post this. But I really haven't seen any other implementation that gives the quality I needed.
/**
* Converts an HSL color value to RGB. Conversion formula
* adapted from http://en.wikipedia.org/wiki/HSL_color_space.
* Assumes h, s, and l are contained in the set [0, 1] and
* returns r, g, and b in the set [0, 255].
*
* @param {number} h The hue
* @param {number} s The saturation
* @param {number} l The lightness
* @return {Array} The RGB representation
*/
function hue2rgb($p, $q, $t){
if($t < 0) $t += 1;
if($t > 1) $t -= 1;
if($t < 1/6) return $p + ($q - $p) * 6 * $t;
if($t < 1/2) return $q;
if($t < 2/3) return $p + ($q - $p) * (2/3 - $t) * 6;
return $p;
}
function hslToRgb($h, $s, $l){
if($s == 0){
$r = $l;
$g = $l;
$b = $l; // achromatic
}else{
$q = $l < 0.5 ? $l * (1 + $s) : $l + $s - $l * $s;
$p = 2 * $l - $q;
$r = hue2rgb($p, $q, $h + 1/3);
$g = hue2rgb($p, $q, $h);
$b = hue2rgb($p, $q, $h - 1/3);
}
return array(round($r * 255), round($g * 255), round($b * 255));
}
/* Uncomment to test * /
for ($i=0;$i<360;$i++) {
$rgb=hslToRgb($i/360, 1, .9);
echo '<div style="background-color:rgb(' .$rgb[0] . ', ' . $rgb[1] . ', ' . $rgb[2] . ');padding:2px;"></div>';
}
/* End Test */