1. An image processing system comprising: an individual data generation unit generating individual 3-dimensional shape data representing the 3-dimensional shape of an individual object and individual texture data representing the texture of the individual object based on a 3-dimensional shape parameter and texture parameter using, a generalized 3-dimensional object model which is calculated based on 3-dimensional shape data and texture data of a plurality of objects similar to one another; a generalized illumination basis model generation unit generating a generalized illumination basis model which corresponds to the generalized 3-dimensional object model and is used for generating illumination basis representing a basic variation in a reflection state caused due to a difference in the direction or intensity of illumination projected onto an individual object; and a second illumination basis calculation unit calculating an individual illumination basis representing a variation in the luminance value of each portion of the 3-dimensional surface of the individual object under various illumination conditions using the generalized illumination basis model generated by the generalized illumination basis model generation unit.