A non-transitory computer-readable storage medium storing an image processing program that causes a computer to execute an image processing method comprising acquiring step of acquiring an input image generated by image pickup through an optical system, generating step of generating a point spread function by using coefficient data of a function approximating a point spread function corresponding to an image-pickup condition of the optical system, and providing step of providing unsharp mask processing to the input image using a filter generated based on information of the point spread function generated by using the coefficient data. The filter is a filter having two-dimensional data.