A method of driving a display device includes driving a light source unit with a first driving ratio and outputting received image data to a display panel of the display device, storing the received image data upon receipt of a signal indicating a still image is displayed, calculating a second driving ratio of the light source unit from a representative value of the stored image data, compensating the stored image data according to the second driving ratio, driving the light source unit with the second driving ratio that is lower than the first driving ratio, and outputting the compensated image data to the display panel.