An organic light emitting display includes a display panel including a plurality of pixels, a compensation area setting unit for selecting an additional compensation requirement area, that is more excessively degraded than an average degradation, based on degradation detection data indicating a degradation degree of organic light emitting diodes formed in the pixels, an edge information extraction unit that analyzes input image data corresponding to the additional compensation requirement area and obtains edge information of an input image, a compensation gain calculation unit for differentially calculating a compensation gain to be applied to compensation data in each of the compensation blocks belonging to the additional compensation requirement area based upon an amount of edge information; and a data modulation unit producing modulation image data to be displayed on the display panel.