HIGHLY EFFICIENT CODING SCHEMES FOR CONTOUR LINES BASED ON CHAIN CODE REPRESENTATIONS

Highly efficient coding schemes for contour line drawings based on chain code representations are proposed. The encoding schemes utilize the first- and second-order Markov models to describe the source structure. Two coding techniques, Huffman encoding and arithmetic encoding, are employed to achieve a high coding efficiency. Universal code tables which match the statistics of contour line drawings obtained from 64 contour maps are presented and can be applied to encode all contour line drawings with chain code representations. Experiments have shown about a 50% improvement on the code amount over the conventional chain encoding scheme with arithmetic coding schemes, and also have shown a comparable compression rate to that obtained by Kaneko and Okudaira with Huffman coding schemes while the implementation is substantially simpler.