1. An image processing method, comprising: a step of obtaining an input image; and a transformation step of performing multiple image transformations including multiple geometric transformations, the transformation step including calculating correspondences between image coordinates of the input image and image coordinates of an output image based on multiple coordinate transformation equations corresponding to geometric transformations, then defining pixel values of a corresponding output image based on pixel values of the input image, and interpolating space pixels of the output image that do not have corresponding pixels in the input image once for each space pixel.