Distinctive Random Colour Generation

gistfile1.php

function randomColor($id){
    $rawR = mt_rand(0, 10) * 25.5;
    $rawG = mt_rand(0, 10) * 25.5;
    $rawB = mt_rand(0, 10) * 25.5;

    $mix = ceil(($id % 5) / 5 * 255);
    $r = ceil(($rawR + $mix) % 255);
    $g = ceil(($rawG + $mix) % 255);
    $b = ceil(($rawB + $mix) % 255);
    return str_pad(dechex(($r << 16) | ($g << 8) | $b), 6, '0', STR_PAD_LEFT);
}