A display device includes a display panel including pixels for displaying four colors including a white color. The display device further includes a signal converter for generating four output signals pertaining to the four colors using three input signals pertaining to three non-white colors of the four colors. The display device further includes a signal processor for processing the output signals to generate data signals and to provide the data signals to the display panel for the pixels to display an image. The signal converter includes at least one adder and a plurality of bit shifters for calculating a white-signal candidate using signals related to the input signals. The signal converter may determine a white-related output signal of the output signals using the white-signal candidate.