Extracting compact objects using linked pyramids

This correspondence describes a method of extracting compact regions from images using three multiresolution (``pyramid'') representations of image features. The method makes use of a gray-level pyramid in which linking of similar nodes at successive levels smooths the image into uniform regions; an edge pyramid in which linking of similarly oriented edge elements serves to delineate the boundaries of the detected regions; and a ``surroundedness'' pyramid in which pixels surrounded by edges are detected.