A display device includes a color transformer and an image controller. The color transformer receives and transforms a three-color image into a four-color image. The four-color image includes a red image, a green image, a blue image, and a white image. The image controller calculates decrement offsets of the red image, the green image, and the blue image, and a compensation value of the white image. The image controller calculates gray level values of the red image, the green image, and the blue image when a value of the white image is zero. The image controller respectively calculates a red image control signal, a green image control signal, and a blue image control signal based on the gray level values and the decrement offsets, and the image controller calculates a white image control signal based on the gray level values and the compensation value of the white image.