1. An image processing apparatus comprising: a normal-phase candidate position selection unit configured to select a position different from a target position on an input image as a normal-phase candidate position, which is a candidate for a position at which jaggies are in the same phase as the target position; a reverse-phase candidate position selection unit configured to select a position different from the target position on the input image as a reverse-phase candidate position, which is a candidate for a position at which jaggies are in a reverse phase to the target position; a weight value calculation unit configured to calculate a weight value based on a first degree of similarity between an image of the target position and an image of the normal-phase candidate position; and a weighted expected value calculation unit configured to calculate a weighted expected value based on the weight value and a pixel of the reverse-phase candidate position.