1. An image processing method for processing an image generated by image pickup using an optical system, comprising: a step of acquiring the image; an image restoration step of performing image restoration processing to reduce a blur component of the image using an image restoration filter; and a distortion correction step of performing geometric transformation processing to reduce a distortion component of the image on which the image restoration processing has been performed, wherein the image restoration processing is performed using image information of an area removed by the geometric transformation processing in the image.