RGBA to HSLA

RGBAtoHSLA.js

function RGBAtoHSLA(r, g, b, a) {
	var
	min = Math.min(r, g, b),
	max = Math.max(r, g, b),
	diff = max - min,
	hsla = [0, 0, (min + max) / 2, a];

	if (diff != 0) {
		hsla[1] = hsla[2] < 0.5 ? diff / (max + min) : diff / (2 - max - min);

		hsla[0] = (r == max ? (g - b) / diff : g == max ? 2 + (b - r) / diff : 4 + (r - g) / diff) * 60;
	}

	return hsla;
}