Embedded Zerotree Wavelet Image Coder With Error Detection Capability For Image Transmission Over Noisy Channels

Abstract

Embedded Zerotree Wavelet (EZW) is an image compression algorithm, having the property that the bits in the bit stream are generated in order of importance, yielding a fully embedded code. The embedded coding can stop encoding at any point to satisfy a target bit rate. It is a wavelet based image compression algorithm, thus relatively few coefficients are needed to represent the image. The problem with EZW image coder that it is highly susceptible to transmission errors. A single corrupted bit will render the remainder of the transmission completely meaningless. The zerotree symbols have to be protected before transmitted over noisy channels. A newly introduced adaptive arithmetic coding with error detection capability (Boyd, Cleary, Irvine, Mekhert, FRIten, 1997) become a simple but effective to replace the previous version of adaptive arithmetic coding used by EZW. The aim of this research is to find the possibilities of integrating adaptive arithmetic coding with error detection capability into EZW image coder constructing a joint source-channel coder. The most obvious reason for wanting the source coder to act also as a channel coder is that software, hardware or computation time can be saved by having a single coding engine that performs bothftmctions. The coder simulation has been presented. The results are not highly accurate, but at least, acceptable results have been shown. An assumption of implementing this technique to the results from original paper by Shapiro et. Al (1992, _1993) has been taken. Even the redundancy has been added to the compressed file, it is shown that the file size is not significantly increased This technique can be used for wireless applications because of relatively few coefficients required to represent an image. Besides, the error detection scheme has been added thus it is possible to transmit EZW compressed image over noisy channels.