public function getHue() {
		$rgb = $this->rgb;
		$r = (($rgb >> 16) & 0xff) / 255;
		$g = (($rgb >> 8) & 0xff) / 255;
		$b = ($rgb & 0xff) / 255;
		$hue = rad2deg(atan2(1.7320508075688 /* = sqrt(3) */ * ($g - $b), 2 * $r - $g - $b));
		return $hue >= 0 ? $hue : 360 + $hue;
	}