There is disclosed an image processing method in which a video signal is inputted from an imaging optical system in which astigmatism remains, and is displayed on a two-dimensional display apparatus. Based on the circumferential direction modulation factor and radial direction modulation factor of a lens used in the imaging optical system, a signal including the amount of vertical or horizontal modulation factor correction proportional to an nth power (n is an integer greater than 1) of a distance from a center position of a screen of the two-dimensional display apparatus is outputted for at least one vertical or horizontal frequency of the two-dimensional display apparatus.