A display device has a pixel that is defined by a plurality of sub-pixels. The sub-pixels include a red sub-pixel representing red, a green sub-pixel representing green, a blue sub-pixel representing blue and a yellow sub-pixel representing yellow. When the pixel represents white, the luminance of the red sub-pixel is lower than its luminance corresponding to the highest gray scale level. In one embodiment, when the pixel represents white, the luminance of the red sub-pixel is preferably in the range of 25% to 96% of its luminance corresponding to the highest gray scale level. Also, the color temperature of white represented by the pixel is preferably higher than 4200 K, more preferably higher than 5000 K.