A timing controller includes a degradation quantity generator, a degradation quantity accumulator, a feedback data generator, and a feedback reflector. The degradation quantity generator generates a degradation quantity for each of a plurality of pixels in a display panel based on image data. The degradation quantity accumulator generates an accumulated degradation quantity based on the degradation quantity for each of the pixels. The feedback data generator generates feedback image data based on the accumulated degradation quantity. The feedback reflector generates image data, in which the degradation quantity is compensated, based on the image data and the feedback image data. An absolute value of the feedback image data, when the accumulated degradation quantity is a first accumulated degradation quantity level, is greater than an absolute value of the feedback image data when the accumulated degradation quantity is a second accumulated degradation quantity level higher than the first accumulated degradation quantity level.