The upper half region is filled with hsl color.
The lower half region is filled with rgb color equivalent.
This is javascript implementation of wikipedia.
function hsl2rgb(h, s, l) { s = s / 100; l = l / 100; let c = (1 - Math.abs(2*l-1)) * s; // chroma h = h / 60; let x = c * (1 - Math.abs((h % 2) - 1)); let r = 0, g = 0, b = 0; if (h < 1) r = c, g = x; else if (h < 2) r = x, g = c; else if (h < 3) g = c, b = x; else if (h < 4) g = x, b = c; else if (h < 5) r = x, b = c; else r = c, b = x; let m = l - c/2; return {r: (r+m)*255, g: (g+m)*255, b: (b+m)*255}; }