Embedded Zero-Tree Wavelet (EZW) image CODEC

Abstract

This paper describes the software implementation of Wavelet based EZW Image CODEC (Encoder and Decoder). The Codec is used to compress and decompress gray scale image in image compression system. The Embedded Zero Tree Wavelet algorithm (EZW) used here is simple, specially designed for wavelet transform and effective image compression algorithm. This algorithm is devised by Shapiro and it has property that the bits in the bit stream are generated in order of importance, yielding a fully embedded code. EZW algorithm is based on the selection of significant coefficients with respect to given thresholds. It is fairly general and performs remarkably well with most types of images. Also, it is applicable to transmission over a noisy channel. The paper focuses on Embedded Zerotree Wavelet (EZW) compression for images. The objective is to study Discrete Wavelet Transform (DWT) and implement EZW algorithm on various gray scale images. Finally, a MATLAB program is written to achieve an image compression based on EZW algorithm. Some experimental results for various types of images are also included in performance analysis of this paper.