Lempel-Ziv-Welch Compression Algorithm with Exponential Decay

Abstract

This paper proposes an improvement over Lempel-Ziv-Welch (LZW) compression algorithm by employing a new method that uses exponential decay (ED) as a tool to manage and remove infrequently used entries in the LZW dictionary. The presented results demonstrate that ED may be an efficient tool to manage and refresh the LZW dictionary. The achieved compression ratio is higher than in the traditional methods like Dictionary Reset DR and Least Recently used LRU. The experimental results demonstrate that the dictionary refresh by the ED may provide higher compression ratio, compared with the original LZW algorithm. In order to investigate the benefits of ED method, it is compared with some other way of LRU-based enhancements. In particular, we consider a LRU-like LZW scheme with Huffman coding of difference from last used word.