A display unit including pixels which display an image according to an image data signal transferred corresponding to each of the pixels, and a controller to receive and convert an external input video signal to transfer a luminance conversion data signal corresponding to the respective pixels. The controller includes: an input image data to receive the external input video signal; a scale factor calculation unit to determine at least one control factor for luminance conversion with respect to an input video signal corresponding to the pixels received from the input image data receiving unit; and a luminance data conversion unit to convert luminance data with respect to the respective pixels using the at least one determined control factor and to output the luminance conversion data signal.