1. A method for detecting an afterimage candidate region, the method comprising: comparing gradation data of an n-th frame with integrated gradation data of an (n−1)-th frame and generating integrated gradation data of the n-th frame, wherein n is a natural number; provides the integrated gradation data of the (n−1)-th frame for the comparing, and storing the integrated gradation data of the n-th frame; and detecting the afterimage candidate region based on the integrated gradation data of the n-th frame, wherein each of the integrated gradation data of the n-th frame and the integrated gradation data of the (n−1)-th frame comprises a comparison region and a gradation region, the comparison region has a size of a-bits and the gradation region has a size of b-bits, wherein a and b are natural numbers.