A data conversion unit includes a gamma conversion unit configured to generate a first gamma data by gamma-converting a first data supplied from an outside thereof, a representative luminance value calculation unit configured to calculate a representative luminance value of an entire panel, based on the first gamma data, a subtraction unit configured to subtract the calculated representative luminance value from gamma conversion values of respective pixels included in the first gamma data, a compensation unit configured to generate a second gamma data by converting the gamma conversion values of the respective pixels, based on the subtracted values corresponding to the respective pixels, and an inverse gamma conversion unit configured to generate a second data by inverse-gamma-converting the second gamma data.