OPTIMIZATION OF LZW (LEMPEL-ZIV-WELCH) ALGORITHM TO REDUCE TIME COMPLEXITY FOR DICTIONARY CREATION IN ENCODING AND DECODING

Abstract

LZW (Lempel-Ziv-Welch) is a universal lossless data compression algorithm, which takes linear time in encoding and decoding. This paper discusses a methodology to reduce time complexity by combining binary search with LZW. The existing LZW compression algorithm takes large time for dictionary creation while encoding and decoding. By using binary search with LZW the time complexity can be reduced optimally and gradually because the comparison ratio is less while creating the dictionary. Especially while compressing the search for patterns in the table and also in the decompression algorithm for finding the pattern in the table is taking linear time for searching. Therefore, combining Enhanced LZW with binary search reduces the time complexity. The proposed methodology may be bust in data compression for communication, Maximizes the reduction of complexity in pattern identification for compression. The proposed methodology reduces the complexity in time with Binary search tree (BST). The experimental result shows 94.21 % improvement on Compression and 93.34% improvement on Decompression.