Issue No. 05 - May (1983 vol. 5)
Daniel K. Scholten , Department of Electrical Engineering, University of Virginia, Charlottesville, VA 22901; The Analytic Sciences Corporation, Reading, MA 01867.
Stephen G. Wilson , Department of Electrical Engineering, University of Virginia, Charlottesville, VA 22901.
This paper investigates the performance of chain code quantization of general curves using a hexagonal lattice structure, as a means of improving efficiency over the standard square lattice. Performance is first computed theoretically, assuming a generalization of grid-intersect quantization, and the curve to be quantized is assumed to be a straight line. An algorithm is then developed to perform chain coding using the hex lattice. Computer simulations were performed to evaluate hexagonal chain coding for a variety of curves, including circles of various curva-ture, straight lines, and a stochastic curve model. We find that the straight-line theory is substantiated for curves whose radius of curvature is roughly twice the lattice constant. For a given peak error in quanti-zation, hexagonal coding reduces the bit rate about 15 percent relative to the square lattice codes, and exhibits qualitative improvements in fidelity as well.
S. G. Wilson and D. K. Scholten, "Chain Coding with a Hexagonal Lattice," in IEEE Transactions on Pattern Analysis & Machine Intelligence, vol. 5, no. , pp. 526-533, 1983.