The Block LZSS Compression Algorithm

The mainstream compression algorithms, such as LZ, Huffman, PPM etc., have been extensively studied in recent years. However, rather less attention has been paid to the block algorithm of those algorithms. The aim of this study was therefore to investigate the block LZSS. We studied the relationship between the compression ratio of block LZSS and the value of index or length. We found that the bit of length has little effect on the compression performance of block LZSS, and the bit of index has a significant effect on the compression ratio. Results of the experiment show that to obtain better efficiency from block LZSS, a moderate sized block which is greater than 32KiB, may be optimal, and the optimal block size does not depend on file types. We also investigated factors which affect the optimal block size. We use the mean block standard deviation (MBS) and locality of reference to measure the compression ratio. we found that good data locality implies a large skew in the data distribution, and the greater data distribution skew or the MBS, the better the compression ratio.