A display device includes a display panel and a display panel driver. The display panel includes pixels. The display panel driver determines an average image load of input image data, determines an operation mode based on a grayscale value of the input image data and the average image load as a first operation mode or a second operation mode, applies a first scale factor to the input image data in the first operation mode, applies a second scale factor different from the first scale factor to the input image data in the second operation mode, and drives the display panel.