A brightness information generation unit 13 generates brightness profiles, serving as brightness information, from each Sobel image formed by an image transformation unit. A feature point detection unit 14 extracts feature points from the generated brightness information. In this case, maximum points (hereinafter, referred to as “peaks”) in the brightness profiles generated from the Sobel image are determined and detected as feature points. A layered structure identification unit 15 identifies the kind of the boundary of each layer or that of the layer in the retina. To identify the kind of the layer or boundary, brightness values in an area between the peaks are obtained from a median image and the layered structure in the area between the peaks is determined, thus identifying the kind of the layer or boundary corresponding to each peak on the basis of information indicating the determination.
