Descriptions of image intensity structure via scale and symmetry

The authors describe an image analysis that provides a quasi-hierarchy of image regions in terms of which humans can quickly build object regions by an interactive approach. This hierarchy is generated by the ridge structure of the intensity surface corresponding to the image. These ridges, in turn, are defined by an intensity axis of symmetry (IAS), which forms a branching structure in which the branches correspond to image regions and the parent/child relationships indicate ridge/subridge structure. The parent/child relationships are computed by following the IAS structure through changes in spatial scale, with scale change achieved by a diffusion in which conduction may be related to edge strength