1. An image processing apparatus comprising: an intermediate image generating unit configured to input an image which has been shot with differing exposure times set by region, generate a plurality of exposure pattern images corresponding to differing exposure times based on said input image, and generate a plurality of timing images which are difference images of said plurality of exposure pattern images; and a distortion correction processing unit configured to generate a corrected image equivalent to an exposure processing image at a predetermined exposure time by synthesizing processing of said plurality of timing images.