1. An image processing apparatus configured to generate a corrected image in which a deterioration caused by an aberration of an image capturing system is restrained, using a plurality of parallax images mutually having parallaxes generated by the image capturing system, the image processing apparatus comprising: a weight generator configured to generate a plurality of weights as weighting data each of which corresponds to one of the parallax images, based on at least one of a pixel value and a pixel value gradient of a corresponding pixel in the plurality of parallax images; and an image generator configured to generate the corrected image using a result of applying each weight to a corresponding one of the plurality of parallax images.