【作者】 蔡文君；

【导师】 李玲远；

【作者基本信息】 华中师范大学 ， 电路与系统， 2005， 硕士

【摘要】 随着多媒体技术的越来越多的应用,需要既有较高的压缩性能又有新功能的图像压缩。为了在静止图像编码的特殊领域里达到这个需求,一个新的标准应运而生,这就是JPEG2000。 JPEG2000标准是由ISO/ITU-T最近开发的图像压缩标准,它的Part Ⅰ(核心编码算法)已经于2000年12月份正式成为了国际标准。JPEG2000在单一的比特流中提供了多种功能,感兴趣区域(ROI)图像编码处理是JPEG2000标准中提供的一种新特性,该编码处理方法可以将用户感兴趣的图像区域(ROI)与背景区域区别开来,并实现对前者优先、优质的编码操作。 本文首先概述了JPEG2000静态图像压缩标准的基本情况,并按照JPEG2000图像标准的正向编码处理顺序,深入分析了JPEG2000编码器的各个编码模块,并重点对核心算法EBCOT做了分析。接着讨论了JPEG2000中三种有效的ROI编码机制:叠块、编码块选择和系数位移,重点分析了最大位移法的编码技术,并且通过实验比较了最大位移法和编码块选择两种方法的编码性能。最后对改进的ROI编码算法进行了实现和分析,实验结果表明,这种算法结合了JPEG2000标准中定义的两种标准ROI编码算法的优点。更多还原

【Abstract】 With the increasing use of multimedia technologies, image compression requires higher performance as well as new features. To address this need in the specific area of still image encoding, a new standard is currently being developed, the JPEG2000.JPEG2000 is the latest image compression standard developed by ths ISO/ITU-T. JPEG2000 Part I ,the core-coding algorithm, became an international standard in December 2000. JPEG2000 provides, in a single bit-stream, a broad set of functionalities. Region-Of-Interest (ROI) image coding is a new feature in the JPEG2000 , which allows ROIs to be coded with better quality than the rest of an image, i.e., background.Firstly the general information of the JPEG2000 still image compression standard is outlined, and each part of the JPEG2000 coder is discussed in detail according to the JPEG2000 encoding order, especially about the EBCOT codec. The three methods by which ROI coding can be achieved in JPEG2000 (tiling; code-block selection; and coefficient scaling) are then discussed, especially ths Maxshift method is analysed. Then the relative performances of Maxshift method and code-block selection are experimentally investigated. Finally we realized modified ROI coding method. The experimental results show that the modified ROI coding method combines the advantages of the two standard ROI coding methods defined in JPEG2000.更多还原