A display device includes: a display region including a first pixel region, a second pixel region, and a third pixel region; a dummy region including a first dummy region disposed between the second pixel region and the third pixel region; first, second, and third pixels respectively arranged in the first pixel region, the second pixel region, and the third pixel region in a matrix of vertical lines and horizontal lines; a data converter configured to: receive first image data including effective data corresponding to the display region and dummy data corresponding to the dummy region; and generate second image data by converting a gray scale value of dummy data corresponding to at least one region of the first dummy region in the first image data into a predetermined first gray scale value, the first gray scale value being between a lowest gray scale value and a highest gray scale value.