1. A flat panel display, comprising: a look-up table (LUT) storing a dither mask; a dithering unit configured to produce at least one additional dither mask based on the dither mask stored in the LUT, and to apply different dither masks to image data during each successive frame period to generate dithered data, wherein the number of perceived gray levels of the dithered data is greater than the number of perceived gray levels of the image data; and a sub-frame mapping unit configured to map the dithered data to a plurality of sub-frame data patterns included in one frame and to output the mapped data.