1. An image processing method, comprising: obtaining a normal image captured with all polarization components of light from an object, and a polarization image captured with specific polarization components out of all the polarization components of the light; generating a difference image between the normal image and the polarization image; calculating, using pixel values of the difference image, a coefficient to be multiplied by at least one of a pixel value of the normal image and a pixel value of the polarization image; and synthesizing the normal image and the polarization image using a pixel value obtained by multiplying the coefficient by the at least one of the pixel value of the normal image and the pixel value of the polarization image to generate a synthesized image.