1. An apparatus of converting an input color image signals into an output color image signals including a white signal, the apparatus comprising: a value extracting unit that extracts a maximum luminance and a minimum luminance among a set of the input color image signals; an area determining unit that determines scaling areas belonged to the input color image signals on the basis of the maximum luminance and the minimum luminance; and a color converting unit that converts the set of the input color image signals into a set of the output color signals depending on the area determination, wherein the scaling areas includes a fixed scaling area and a variable scaling area.