rgb2hsl · PHP Function to Convert Colors from RGB to HSL

function rgb2hsl ($r, $g, $b) {
    $r /= 255;
    $g /= 255;
    $b /= 255;
    $max = max($r, $g, $b);
    $min = min($r, $g, $b);
    $l = ($max + $min) / 2;
    if ($max == $min) {
        $h = $s = 0;
    } else {
        $d = $max - $min;
        $s = $l > 0.5 ? $d / (2 - $max - $min) : $d / ($max + $min);
        switch ($max) {
            case $r:
                $h = ($g - $b) / $d + ($g < $b ? 6 : 0);
                break;
            case $g:
                $h = ($b - $r) / $d + 2;
                break;
            case $b:
                $h = ($r - $g) / $d + 4;
                break;
        }
        $h /= 6;
    }
    $h = floor($h * 360);
    $s = floor($s * 100);
    $l = floor($l * 100);
    return ['h' => $h, 's' => $s, 'l' => $l];
}