def RGB_to_CMY(cobj, *args, **kwargs):
    """
    RGB to CMY conversion.

    NOTE: CMYK and CMY values range from 0.0 to 1.0
    """
    cmy_c = 1.0 - cobj.rgb_r
    cmy_m = 1.0 - cobj.rgb_g
    cmy_y = 1.0 - cobj.rgb_b

    return CMYColor(cmy_c, cmy_m, cmy_y)