public final float hue(int what) {
    if (what != cacheHsbKey) {
      Color.RGBtoHSB((what >> 16) & 0xff, (what >> 8) & 0xff,
                     what & 0xff, cacheHsbValue);
      cacheHsbKey = what;
    }
    return cacheHsbValue[0] * colorModeX;
  }