PROBLEM TO BE SOLVED: To provide a technique for adaptively acquiring, from a tomographic image of an eye, diagnostic information data of the eye for diagnosing a plurality of diseases without increasing the burden on a user.SOLUTION: The tomographic image of the fundus of the subject's eye is acquired. A prescribed layer boundary is detected from the tomographic image. The new layer boundary is presumed based on the prescribed layer boundary. A region where the thickness becomes a threshold or more is decided among the region between the prescribed layer boundary and the new layer boundary.
