RGB, HSL, HUE色彩系统互转

  HSLToRGB = function (hsl) {
    var m1, m2, r, g, b;
    var h = hsl[0], s = hsl[1], l = hsl[2];
    m2 = (l <= 0.5) ? l * (s + 1) : l + s - l*s;
    m1 = l * 2 - m2;
    return [this.hueToRGB(m1, m2, h+0.33333),
        this.hueToRGB(m1, m2, h),
        this.hueToRGB(m1, m2, h-0.33333)];
  }


  hueToRGB = function (m1, m2, h) {
    h = (h < 0) ? h + 1 : ((h > 1) ? h - 1 : h);
    if (h * 6 < 1) return m1 + (m2 - m1) * h * 6;
    if (h * 2 < 1) return m2;
    if (h * 3 < 2) return m1 + (m2 - m1) * (0.66666 - h) * 6;
    return m1;
  }


  RGBToHSL = function (rgb) {
    var min, max, delta, h, s, l;
    var r = rgb[0], g = rgb[1], b = rgb[2];
    min = Math.min(r, Math.min(g, b));
    max = Math.max(r, Math.max(g, b));
    delta = max - min;
    l = (min + max) / 2;
    s = 0;
    if (l > 0 && l < 1) {
      s = delta / (l < 0.5 ? (2 * l) : (2 - 2 * l));
    }
    h = 0;
    if (delta > 0) {
      if (max == r && max != g) h += (g - b) / delta;
      if (max == g && max != b) h += (2 + (b - r) / delta);
      if (max == b && max != r) h += (4 + (r - g) / delta);
      h /= 6;
    }
    return [h, s, l];
  }