A capturing parameter and a capturing image are obtained by an image capturing device which uses the capturing parameter. Correction data, which corresponds to an optical transfer function of the image capturing device derived from the capturing parameter, and a noise amount of the capturing image dependent on the capturing parameter, is acquired to correct a blur of the capturing image. A first degree of correction by the correction data for a high noise amount is less than a second degree of correction by the correction data for a low noise amount.