| Image compression technology is one of the key points in modem multimedia and communication area. At present, there are many types of compression technologies.Wavelet transform has been become a new signal analysis tool, because it overcomes the limitation of the fourier transform, and has good time-frequency adaptive property and multi-resolution analysis.But, the wavelet transform are not perfect and algorithms of the wavelet transform have many pitfalls in regard to it's speed, complexity and compressing performance. So it is important and imperative to perform the study on the wavelet image compression algorithm along with its application.Firstly, the image compression's necessary and feasibility are discussed, and several classical image coding technologies are introduced.Secondly, based on analyzing the characteristic of image compression based on wavelet transform, both crucial questions and ordinary steps of the wavelet transform used in image compression are exploited.Finally, the algorithm encoded zero-tree wavelet is analyzed and discussed in detail. and a improved algorithm based on zero-tree is proposed, which adjusts the structure of the zero-tree rationally based on the classic EZ coding technology, extends the signals of the zero-tree from four to six. It also changes the original coding flow, which results in the adjustment of processes of main scanning, assistant scanning, and decoding.Experimental results show that the compression ratio of the zero-tree-based algorithm is far more excellent than that of the EZW-based one, and its codes can be intercepted at random without any additional distortion, and it remains the high quality of the original image. Certainly, the novel zero-tree algorithm still has some shortage to be improved.
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