摘要
信息时代的到来使人们极易获得大量的信息，数字图像就是一种重要的信息载体。如何存储和传输这些图像一直是人们关注的焦点，对此，人们也提出了许多方法和制定了许多标准。小波变换作为一门较新的数学分支，被引入图像处理以后，很快引起了人们的极大兴趣。随着研究的开展，相继出现了许多基于小波变换的图像压缩方式，如嵌入式零树算法（EZW，the Embedded Zerotree Wavelet algorithm ）、分层树集合分割算法（SPIHT，Set Partitioning In Hierarchical Trees）、最佳截断嵌入码块算法 ( EBCOT ，Embedded Block Coding with Optimized Truncation)等等，在此基础上，人们还制定了基于小波变换的国际化图像压缩标准JPEG2000。
本文首先介绍了小波变换理论的发展情况和一些基本的小波理论，然后又介绍了几种基于小波变换的图像压缩技术并对它们做了简单的比较，紧接着重点论述了EZW算法的原理和实现，这也是本文的重点。最后，实现了基于EZW算法的一个软件系统。
关键词： 图像压缩，小波，离散小波变换，EZW算法
ABSTRACT
People can easily obtain a large amount of information with the arrival of the information age, digital image is an important information carrier. How to store and transmit these digital images has been the focus of people's attention, thus, many methods were proposed and a number of standards were shaped. As a relatively new branch of mathematics, wavelet transform has been introduced into image processing, and quickly caught the great interest. Following this study, many image compression methods which based on wavelet transform have been launched, for example, the Embedded Zerotree Wavelet algorithm (EZW), Set Partitioning In Hierarchical Trees (SPIHT), Embedded Block Coding with Optimized Truncation (EBCOT), and so on. On these basses, it has developed international image compression standard JPEG2000 based on wavelet transform.
Firstly, this paper introduces the basic wavelet transform theory and the development of the wavelet theory, then introduces several image compression technology based on wavelet transform , compares them Simply, and treatises the EZW algorithm and its implementation, which is the focus of this paper. Finally, it’s realized a software system based on the EZW algorithm.
KEY WORDS: Image compressing, Wavelets, Discrete Wavelet Transform, EZW algorithm
