Improvement Of Zero-tree Coding Algorithm

As the requirement of communication is increasing in modern information world, there is a conflict between the transportation of image and the capacity of data channel. A large image without compression cost too much in transportation. People are taking the efficiency of image compressing for more consideration. So far, the wavelet transform method is very popular in image compression, especially the EZW algorithm.The thesis will give an introduction to some basic concepts in wavelet transform first which includes the continuous wavelet transform, the discrete wavelet transform, multiresolution analysis and mallat algorithm. It will refer to some application of wavelet transform in image compression. Secondly, the whole process of EZW algorithm will be mentioned followed by some improved EZW algorithm in nowadays. It will draw some conclusions for the disadvantage of EZW algorithm in coding efficiency by learning the process of the coding algorithm. After that, the thesis will introduce an improved EZW algorithm based on scalariform quantization. The new algorithm can fix some redundancy treating in reorganizing the symbol for wavelet coefficients. Finally, we will draw some conclusion after some experiments by comparing the two methods. PSNR and the coding speed will be the parameters for comparing.Based on experiments, this improved algorithm obviously shows the improvement in image coding efficiency and restoration quality.