CMY: returned in range 0.0 - 1.0
        CMY is subtractive, e.g. black: (1, 1, 1), white (0, 0, 0)

def cmy(self):
        """
        CMY: returned in range 0.0 - 1.0
        CMY is subtractive, e.g. black: (1, 1, 1), white (0, 0, 0)
        """
        r, g, b = self.color
        c = 1 - r
        m = 1 - g
        y = 1 - b

        return (c, m, y)