Nazia Sarwat Islam
Prof. Dr.-Ing. Werner Henkel
LZ77, LZ78, and LZW84 are universal lossless data compression algorithms for reducing redundancy. A modiﬁed version of these algorithms that takes into account both forward and reverse readings is presented in this work. It is shown that bi-directional reading can improve the compression ratio at the expense of slight modiﬁcations in LZ algorithms provided that there exists some symmetry in the information content. Modification and simulation of LZ77 and LZ78 had already been completed previously. This project focused on the modification of the LZW compression (LZW84) algorithm. Results were compiled for text, audio and image files. It was observed that, for audio and image files the bi-directional algorithm outperforms the original method. For text files this trend is also observable given that the dictionary size is small.