1. An image processing apparatus that outputs a transformed image obtained by performing geometric transformation on an input image, the image processing apparatus comprising: an identification unit configured to identify, on the basis of inverse parameters of the geometric transformation, a plurality of second sets of coordinates in the input image corresponding to a plurality of first sets of coordinates in the transformed image located within a certain distance from a first set of coordinates; a storage control unit configured to store, among the plurality of first sets of coordinates in the transformed image, sets of coordinates that overlap a plurality of third sets of coordinates in the transformed image located within the certain distance from a second set of coordinates and sets of coordinates identified by the identification unit as sets of coordinates in the input image corresponding to the overlapped sets of coordinates on the basis of the inverse parameters in a memory while associating the overlapped sets of coordinates and the sets of coordinates identified by the identification unit with each other; and a generation unit configured to generate the transformed image by determining pixel values corresponding to the plurality of first sets of coordinates in the transformed image using pixel values corresponding to the plurality of second sets of coordinates identified by the identification unit and pixel values corresponding to the plurality of second sets of coordinates in the transformed image using pixel values corresponding to the sets of coordinates in the input image stored by the storage control unit in the memory.