IMAGE PROCESSING APPARATUS FOR CORRECTING DISTORTION OF IMAGE AND IMAGE SHOOTING APPARATUS FOR CORRECTING DISTORTION OF SHOT IMAGE

A digital camera acquires the image of an original including an original from a shot image acquired by shooting. The digital camera reduces the image of the original and corrects distortion of the reduced image which is originated from the characteristic of a lens. As the digital camera performs distortion correction on the reduced image, the number of arithmetic operations in distortion correction is reduced, making distortion correction simpler. The digital camera acquires a rectangle defined by the contour of the original, extracts the image of the original to acquire an original image before reduction, and acquires an associated projection-transformed image by affine transformation. The digital camera acquires pixel positions of the original image using an affine parameter, and acquires pixel positions of the image before distortion correction using a relational expression of distortion correction performed on the reduced image.