an accumulation determiner which determines an accumulation interval of images based on a first change amount of images in regions of interest in which an afterimage object is disposed and a second change amount of images in entire regions;

an image accumulator which accumulates the images during the accumulation interval to generate accumulated images;

an afterimage object detector which detects the afterimage object from the accumulated images; and

a down-scaler which downscales the images and providing the down-scaled images to the accumulation determiner,

wherein the accumulation determiner includes:

a region of interest calculator which calculates the first change amount by comparing images in the regions of interest;

an entire region calculator which calculates the second change amount by comparing images in the entire regions; and

an accumulation interval determiner which changes the accumulation interval based on the first change amount and the second change amount.