def color_blend(a, b):
    """
    Performs a Screen blend on RGB color tuples, a and b
    """
    return 255 - ((255 - a[0]) * (255 - b[0]) >> 8), 255 - ((255 - a[1]) *
        (255 - b[1]) >> 8), 255 - ((255 - a[2]) * (255 - b[2]) >> 8)
