A polarized image acquisition section shoots a subject through a polarizing element operable to set principal axes of which directions are different from each other. An incident plane specifying section specifies an incident plane of each pixel, and an incident angle computation section computes an incident angle of each pixel. A classifying section clusters pixels similar to each other in both incident plane and incident angle. A reflection component separation section performs reflection component separation on each clustered pixel set on the assumption of probabilistic independence between the diffuse reflection component and the specular reflection component.