1. A method of processing image data, the method comprising: detecting a distribution of gray levels of frame image data by a detector; determining a remapping function for providing remapped gray levels based on the distribution of the gray levels by a remapper, a number of the remapped gray levels being less than a number of the gray levels; and providing low-power frame image data based on the frame image data and the remapping function by a filter, wherein displaying the low-power frame image data uses power lower than displaying the frame image data.