A universal chain code compression method

• A novel universal algorithm for various chain code compressions is presented.
• New chain code binarization scheme is proposed.
• The compression is based on RLE and variation of LZ77.
• The method achieves on average higher compression than state-of-the-art methods.

This paper introduces a new approach for lossless chain code compression. Firstly, the chain codes are converted into the binary stream, independent on the input chain code. Then, the compression is done using three modes: RLE0,LZ770RLE0,LZ770 and COPY  . RLE0RLE0 compresses the runs of the 0-bits, LZ770LZ770 is a simplified version of LZ77LZ77 and handles the repetitions within the bit stream, whilst COPY is an escape mode used, when the other two methods are unsuccessful. This method has been tested on the Freeman chain code in eight and four directions, the Vertex chain code, the Three OrThogonal chain code, and the Normalized angle difference chain code. The experiments confirmed better compression ratios on various benchmark datasets in comparison to the state-of-the-art lossless chain code compression methods.