A display device includes a data mapping unit for extracting a minimum value among three-color input data which respectively correspond to red, green, and blue, determining white color output data by multiplying the extracted minimum value by a gain ratio, and determining red, green, and blue color output data respectively by subtracting the white color output data from the three-color input data; and a gain adjustment unit for determining the gain ratio to minimize a standard deviation respectively for the white color output data and the red, green, and blue color output data.