1. A degradation compensation apparatus, comprising: a calculator provided with gray data regarding a plurality of consecutive frames and configured to calculate and output a frame degradation amount of a current frame, which indicates a degree of degradation of the current frame; a memory configured to accumulate and store the frame degradation amount of the current frame and to output a cumulative degradation amount, which is an accumulated degree of degradation of frames up to the current frame; and a data corrector configured to correct the gray data for a subsequent frame based on the cumulative degradation amount, wherein: each of the plurality of consecutive frames comprises first and second blocks each comprising a plurality of pixels; and the frame degradation amount is calculated based on one of the pixels included in the first block and one of the pixels included in the second block.