1. A computer-implemented image processing method, comprising: a step of obtaining an input image; and a step of obtaining a transformation order of a set of multiple image transformations including at least two geometric transformations and a light amount correction, in accordance with a user's manipulation; and a transformation step of performing the set of multiple image transformations, the transformation step including targeting one of the multiple image transformations from first to last of the transformation order, performing a coordinate transformation corresponding to the geometric transformation targeted, if one of the geometric transformations is targeted, performing interpolation of space pixels due to the coordinate transformation after the coordinate transformation is performed, if the geometric transformation of the last of the transformation order is targeted, avoiding interpolation of the space pixels after the coordinate transformation is performed, if the geometric transformation other than the last of the transformation order is targeted, and performing interpolation of the space pixels before performing correction of pixel values, if the light amount correction is targeted, the light amount correction not being limited to the last of the transformation order, wherein each step of the image processing method is executed by a processor.