文档介绍：中文摘要
摘要
JPEG2000 标准是国际标准组织(ISO)和国际电信联盟(ITU)联合制定的新
一代静止图像压缩标准。与以往的压缩标准相比,JPEG2000 标准具有很多优点,
如良好的低比特率压缩性能、支持图像象素和分辨率渐进传输、支持感兴趣区域编
码等,可应用于数码相机、网络传输、无线通信、医疗图像等领域。但是,JPEG2000
的算法复杂度较大、编解码时间长,制约了它在实时传送等实时性要求高的系统中
的应用。因此,如何在保证压缩性能下提高编解码速度成为了论文研究工作的目的。
本文的主要工作归纳如下:
①在充分分析 JPEG2000 标准中的核心算法(EBCOT)的基础上,发现 EBCOT
算法中的块编码不仅决定了整个系统的压缩性能,而且还占用了整个压缩过程一半
以上的时间。
②通过深入研究块编码,发现分块编码每个位平面上 3 个通道编码输出是不均
衡的。基于此特征,又结合小波系数的特点提出高频子带(HL1、LH1、HH1)较
高位平面进行一次性扫描编码以及较低位平面省略清除通道的编码优化算法。
③设计了优化编码算法的实现方案。
④根据 JPEG2000 标准基本编解码系统框架,在 Microsoft Visual C++ 开发
环境下,用面向对象的编程思想,构造了 JPEG2000 图像编解码实验系统,实现了
用本文优化块编码算法和标准提供的算法对 BMP 灰度静止图像进行无损和有损压
缩的编解码功能。
实验结果分析表明本文优化算法达到了提高编解码速度的目的,同时对静止图
像的无损压缩性能有一定改善,也不会对有损压缩性能造成很大影响,尤其适用于
实时传送图像系统。
关键词:图像压缩、提升小波、JPEG2000、EBCOT、块编码
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英文摘要
ABSTRACT
JPEG2000 is the new standard for pression of still image established by the
anization for Standardization (ISO) and the International
munications Union (ITU). Compared with the former standards, JPEG2000
provides a set of advantages, such as superior low bit-rate performance, excellent
progressive transmission by pixel accuracy and resolution and Region of Interests coding.
It has a great variety of applications such as , digital cameras, wireless
communication, medical images. But pression system of JPEG2000 plex
and needs much time for coding, which is not suitable for the high real-time system.
Therefore, this dissertation aims at finding a solution to speed up coding with the similar
compression performance.
It is summarized as follows:
① Based on full analysis of the core algorithm(EBCOT) in JPEG2000, it is found
that the block coding within the core algorithm not only determines pression
performance of the whole system, but also occupies the time over 50 percent of the whole
compression process.
② Through full research on block coding, a coding feature is found that the three
coding passes of block coding have different need-to-be-coded pixels. Based on this
feature