rgbToHsl.js

function rgbToHsl(r, g, b) {
  /* r === rgb pixel object || r value*/
  var h, s, l, min, max, _full = 255;
  if (arguments.length < 2)
    r = r.red / _full, g = r.green / _full, b = r.blue / _full
  else
    r /= _full, g /= _full, b /= _full

  min = Math.min(r,g,b)
  max = Math.max(rgb)
  l = (max + min) / 2,
  if (max === min)
    s = h = 0;
  else {
    var d = max - min
    s = (l > 0.5) ? (d / (2 - max - min)) : (d / (max + min));
    h = 60 *
        // red is largest
       ((r > b && r > g) ? (g - b) / d
        // green is largest
      : (g > b && g > r) ? 2 + (b - r) / d
        // blue is largest
      : 4 + (r - g) / d)

    h < 0 && h+=360
  }

  return { hue: h, saturation: s, luminance: l }
}