Genera un colore casuale in esadecimale

/**
 * Genera un colore casuale in esadecimale
 * @param  integer [$minVal = 0]   Valore minimo
 * @param  integer [$maxVal = 255] Valore massimo
 * @return string  Colore in esadecimale
 */
function randomColor ($minVal = 0, $maxVal = 255)
{

    // Make sure the parameters will result in valid colours
    $minVal = $minVal < 0 || $minVal > 255 ? 0 : $minVal;
    $maxVal = $maxVal < 0 || $maxVal > 255 ? 255 : $maxVal;

    // Generate 3 values
    $r = mt_rand($minVal, $maxVal);
    $g = mt_rand($minVal, $maxVal);
    $b = mt_rand($minVal, $maxVal);

    // Return a hex colour ID string
    return sprintf('#%02X%02X%02X', $r, $g, $b);

}