A hierarchical description of digital grayscale images based on image dipoles

Deals with a hierarchical description of digital grayscale images based on non-local structural features, called image dipoles. An image dipole is defined to be a region whose lines of slope emanate from the same maximum, and reach the same minimum. Incorporating an image dipole based representation of an image into a scale-space filtering, we propose in this paper a hierarchical image dipole description of the image. The proposed description consists of image dipole networks of some scales, and linking of image dipoles across the scales such that the description contains all local transformations of the image dipole network in the scale-space