A display device includes a display panel and a processor. The panel has pixels including first to fourth sub-pixels. The processor determines candidates for an expansion coefficient of pixels when displaying an image of one frame, determines the coefficient for the one frame, based on each candidate, calculates the output values of a pixel, based on the coefficient and the input values of the pixel, and outputs the output values to the panel. The processor calculates a candidate for the coefficient in the second frame of a pixel, when the input values of this pixel are not substantially the same between first and second frames, and calculates no candidate for the coefficient when the input values of the pixel are substantially the same between the first and second frames.