王衛國 郭寶龍
摘 要 隨着互聯網的普及和圖象應用範圍的不斷擴大,對圖象的編碼提出了新的要求,即不僅要求具有高的壓縮比,還要求有許多新的功能,如漸進編解碼、從有損壓縮到無損壓縮等。嵌入式零樹小波編碼較好地實現了這一思想,因此奠定了它在圖象編碼中的地位。近年來，在嵌入式零樹小波編碼(EZW)算法的基礎上出現了許多新的'改進算法，如多級樹集合分裂算法(SPIHT),集合分裂嵌入塊編碼(SPECK),可逆的嵌入小波壓縮法(CREW)等.本文對這些算法從原理到性能進行了比較和討論,說明了嵌入式圖象編碼的研究方向。
關 鍵 詞 圖象編碼 嵌入式 零樹 小波變換
On Embedded Zerotree Wavelets Coding and other Improved Algorithms
WANG Wei-guo, GUO Bao-long
(School of Mechano-Electronic Engineering,Xidian Univ.,Xi’an 710071)
Abstract With the extensive application of internet and image,some new requirements on image coding,such as high compression rate ,pregressive codec,and compression from lossy to lossless ,are to be e functions can be performed well by EZW(Embedded Zerotree Wavelets) the bases of EZW,many newly improved algorithms have been developed in recent can illustrated by algorithms like SPIHT(Set Partitioning in Hierarchical Trees),SPECK(Set Partitioned Embedded block coder),In this paper,the writer discusses the principles and performances of these algorithms,thus explains the research tendency in the area of embedded image coding.
Keywords Image coding,Embedded,Zerotree,Wavelet transform
0. 引言
在基於小波變換的圖象壓縮方案中,嵌入式零樹小波 EZW(Embedded Zerotree Wavelets)[1]編碼很好地利用小波係數的特性使得輸出的碼流具有嵌入特性。它的重要性排序和分級量化的思想被許多編碼算法所採用。近年來,在對EZW改進的基礎上，提出了許多新的性能更好的算法,如多級樹集合分裂算法