摘要
信息時代的到來使人們極易獲得大量的信息,數(shù)字圖像就是一種重要的信息載體。如何存儲和傳輸這些圖像一直是人們關注的焦點,對此,人們也提出了許多方法和制定了許多標準。小波變換作為一門較新的數(shù)學分支,被引入圖像處理以后,很快引起了人們的極大興趣。隨著研究的開展,相繼出現(xiàn)了許多基于小波變換的圖像壓縮方式,如嵌入式零樹算法(EZW,the Embedded Zerotree Wavelet algorithm )、分層樹集合分割算法(SPIHT,Set Partitioning In Hierarchical Trees)、最佳截斷嵌入碼塊算法 ( EBCOT ,Embedded Block Coding with Optimized Truncation)等等,在此基礎上,人們還制定了基于小波變換的國際化圖像壓縮標準JPEG2000。
本文首先介紹了小波變換理論的發(fā)展情況和一些基本的小波理論,然后又介紹了幾種基于小波變換的圖像壓縮技術并對它們做了簡單的比較,緊接著重點論述了EZW算法的原理和實現(xiàn),這也是本文的重點。最后,實現(xiàn)了基于EZW算法的一個軟件系統(tǒng)。
關鍵詞: 圖像壓縮,小波,離散小波變換,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