Shape Based Retrieval

Abstract

Together with color and texture, shape is one of the basic features in computer vision. Shape analysis methods play an important role in systems for object recognition, matching, registration, and analysis. Research in shape analysis has been motivated, in part, by studies of human visual form perception systems. Several theories of visual form are briefly mentioned here. A proper definition of shape similarity calls for the distinctions between shape similarity in images (similarity between actual geometrical shapes appearing in the images) and shape similarity between the objects depicted by the images, i.e. similarity modulo a number of geometrical transformations corresponding to changes in view angle, optical parameters, and scale. In our shape-based retrieval experiments we concentrate on active contour methods for shape segmentation and invariant moments for shape measures. We implemented two algorithms from the research literature and we applied them on a standard object database.