rgb2hsl.ts•927 B
/**
* @preserve
* Copyright 2015-2018 Igor Bezkrovnyi
* All rights reserved. (MIT Licensed)
*
* rgb2hsl.ts - part of Image Quantization Library
*/
import { min3, max3 } from '../utils/arithmetic';
/**
* Calculate HSL from RGB
* Hue is in degrees [0..360]
* Lightness: [0..1]
* Saturation: [0..1]
* http://web.archive.org/web/20060914040436/http://local.wasp.uwa.edu.au/~pbourke/colour/hsl/
*/
export function rgb2hsl(r: number, g: number, b: number) {
const min = min3(r, g, b);
const max = max3(r, g, b);
const delta = max - min;
const l = (min + max) / 510;
let s = 0;
if (l > 0 && l < 1) s = delta / (l < 0.5 ? max + min : 510 - max - min);
let h = 0;
if (delta > 0) {
if (max === r) {
h = (g - b) / delta;
} else if (max === g) {
h = 2 + (b - r) / delta;
} else {
h = 4 + (r - g) / delta;
}
h *= 60;
if (h < 0) h += 360;
}
return { h, s, l };
}