Algorithms for 2D and 3D image description based on the IAS

The algorithms used in computing the intensity axis of symmetry (IAS) for 2D and 3D medical images are described. The basic 2D algorithms, along with the algorithms needed to incorporate scale space, are described. A brief discussion of the extensions needed to work with 3D images is given. The basic approach is to treat the image as a deformable intensity surface which is contracted onto the IAS. The primitive regions of the segmentation are identified by the branches in the resulting tree-like structure. A hierarchy is produced by following the simplification of the branching through scale space. For comparison papers see ibid., p.94-101 and ibid., p.108-14