LOSSLESS IMAGE COMPRESSION BY INCORPORATING HISTOGRAM PROCESSING STAGE IN BURROWS WHEELER COMPRESSION ALGORITHM (BWCA).

Abstract

Lossless Image Compression by incorporating Histogram Processing stage in Burrows Wheeler Compression Algorithm (BWCA) Lossless Image compression reduces the amount of data required to represent an image without losing any information.Burrows-Wheeler compression is a four stage process in which the data is transformed with the Burrows-Wheeler Transform, and then transformed with Move-To-Front, and then Run Length Encoding is performed and finally encoded with an entropy coder.BWT is a reversible context sorting algorithm and compression is achieved because sorting increase the spatial and temporal redundancy. In this report a new stage is proposed before BWT to enhance compression ratio i.e. histogram processing stage and several other improvements have been proposed in each stage of Burrow wheeler compression algorithm. The proposed scheme is also compared with LZW Lempel Ziv Welch algorithm which is a universal dictionary based algorithm while BWCA is lexographical transform .The focus of this report is to improve the compression ratio of BWCA by introducing histogram processing stage as well as improving GST and RLE stages.