A display device including a data mapping unit configured to identify a minimum value of the three-color input data corresponding to red, green, and blue (RGB), to determine white output color data by multiplying the identified minimum value by a gain ratio, and to subtract the white output color data from each of the three-color input data to determine RGB output color data, a gain adjustment unit configured to determine a preliminary gain ratio to minimize standard deviations of each of the white and RGB output color data, and to change a preliminary gain ratio based on an accumulated sum of color data used for respective sub-pixels in a previously displayed image to determine the gain ratio, and a display unit including unit pixels, each including RGB and white sub-pixels, and configured to display an image which corresponds to the and RGB output color data.