DEVELOPMENT OF A HYBRID LOSSLESS COMPRESSION TECHNIQUE BY CONCATINATION OF LEMPEL-ZIV-WELCH WITH ARITHMETIC CODING ALGORITHMS

Abstract

With scientific experiments revolving around generating, processing, analyzing and continuous storing of data, it is imperative to ensure data generated is compressed as much as possible so that it takes up the least amount of space necessary and is effectively transmitted across various media despite bandwidth limitation. Compression techniques seek to optimize transmission and storage of data due to the fact that presently, the rate of data generation is much faster than what the existing transmission channels can handle effectively. In this research, Lempel-Ziv-Welch (LZW) algorithm was combined with Arithmetic coding algorithm to form a hybrid lossless compression technique (LZW and Arithmetic Coding LAC) that was used to compress text data. The compression was carried out in two stages, LZW performed the first stage of compression, while the arithmetic coding performed the second stage of compression. The hybrid algorithm was coded in C#, and it compression performance was compared with that of LZW and Arithmetic coding respectively. The developed hybrid algorithm (LAC) produced a compression output that was smaller in size compared either LZW algorithm or Arithmetic coding algorithm individually. LAC achieved a mean compression percentage of 54.73% and a compression ratio of 0.45 while LZW achieved a mean compression percentage of 52.67 % with compression ratio 0.47 and Arithmetic coding achieved a mean compression percentage 41.26% with compression ratio of 0.59.