A method and apparatus for classifying population states based on shape characterizations of sub-manifolds of points, curves, surfaces, or sub-volumes. A structure is examined using, for example, clinical imaging techniques such as CT, MRI, or Ultrasound (601). The image is then subjected to a transform function to generate a map (602) of the new image. The new image map which contains information regarding the shape (604) of the structure is compared (606) to average shape characterizing population groups. If the shape of the new image falls within a best match probability with an average shape, the new image is classified (607) as a member of the population characterized by the average shape. Thus, if the shape of the new structure resembles the average shape of a population group, the new shape is classified as the same population state as the other structures displaying the same shape characteristics.