A display device includes: a display panel; a light emitting unit; a driving circuit configured to control a driving current applied to the light emitting unit based on image data; and a controller configured to: obtain a selected mode of one of a low grayscale mode or a high grayscale mode based on a required luminance included in the image data, obtain a minimum value and a maximum value of the driving current based on the selected mode, based on an output range of the driving current being adjusted to obtain an adjusted output range, increase a number of luminance levels expressible within the adjusted output range to obtain an increased number of luminance levels, and control the driving circuit based on the increased number of luminance levels.