Although the conventional b-scale encoding method is well established for nD images (n ≥ 2), we use 2-D b-scale encoding method in this study because low-resolution CT data do not allow continuous analysis of TIB patterns through lowresolution imaging direction. In the 2-D digital space (Z 2 , ν), a scene C = (C, f ) is represented by a pair where C is a rectangular array of voxels, ν = (ν 1 , ν 2 ) indicates the size of the voxels, and f is a function that assigns to every voxel an image intensity value. A ball B k (c) of radius k ≥ 0 and with center at