A data processing device includes a first reference value generator which generates a first reference value corresponding to a ratio of a chromatic color using image signals or first image signals obtained by gamma-compensating the image signals, a white generator which generates a white image signal and second image signals using the first image signals and a second reference value corresponding to an amount of a white data in use, a third reference value generator which generates a third reference value using a first color coordinate corresponding to a color coordinate of the second image signals, a second color coordinate corresponding to a color coordinate of the white image signal, the first reference value, and the second reference value, and a gamut mapper which maps the second image signals to a color coordinate corresponding to the third reference value to generate third image signals.