Image painting is an image doctoring method to remove particular objects. In this paper, a novel passive detection method for paint-doctored JPEG images is proposed when the doctored image is saved in an uncompressed format or in the JPEG compressed format. We detect the doctored region by computing the average of sum of absolute difference images between the doctored image and a resaved JPEG compressed image at different quality factors. There are several advantages of the proposed method: first, it can detect the doctored region accurately even if the doctored region is small in size; second, it can detect multiple doctored regions in the same image; third, it can detect the doctored region automatically and does not need any manual operation; finally, the computation is simple. Experimental results show that the proposed method can detect the paint-doctored regions efficiently and accurately.