The present invention provides a technique to identify layout of surface regions of an object by image area segmentation. A plurality of images is acquired by imaging an object under a plurality of mutually different illumination conditions. By performing area segmentation on this plurality of images, the layouts of the plurality of image areas which is different from the layout of the object surface regions is obtained. Then, the layout of the surface regions on the object is identified based on the layouts of the plurality of image areas.