【作者】 张良；

【导师】 张春田；

【作者基本信息】 天津大学 ， 信号与信息处理， 2003， 博士

【摘要】 网络时代，数字多媒体产品的有效传输和版权保护是信息产业界所面临的重要问题，多媒体数据压缩和数字水印作为与之相关的关键技术而受到众多研究者关注。数字水印是信息隐藏技术的一个现代应用分支，近几年，包括数字水印在内的信息隐藏技术得以快速发展，其应用范围也越来越广泛。本文在详细分析信息隐藏技术特点以及JPEG2000图象编码系统的基础上，与JPEG2000标准紧密结合，提出了三种信息隐藏算法。一是结合信息隐藏技术的感兴趣区图象编码。感兴趣区编码是JPEG2000标准所提供的一项重要特性，本文对标准中规定的两种感兴趣区编码方法进行了分析，指出其不足之处，而后创造性地提出利用信息隐藏技术来对其进行补充，将部分背景区的编码信息隐藏在感兴趣区系数的冗余位，通过控制嵌入量可以调节感兴趣区和背景区的相对质量。二是用于JPEG2000图象版权保护的小波域鲁棒性双水印算法。水印系统受到攻击时水印信息各个部分的受损程度并不相同，本文提出的算法借助于小波分解的多分辨率特性，利用一个参考水印来调整主水印各个部分的可信度，减少攻击造成的影响。三是基于信息隐藏的图象数据恢复技术。该方案针对JPEG2000基本编码系统，首先对量化前的小波系数进行非线性处理；然后估算出量化以后各个小波系数上所存在的冗余的相对大小，根据估算的冗余对各个嵌入点处的嵌入强度进行图象自适应调整；最后根据小波分解的特性选取码流中的重要信息作为隐藏信息嵌入到图象的高频分量当中，从而实现对码流的非均等差错保护。更多还原

【Abstract】 In cybertimes, it is very important for the information industry to insure the effective transmission and copyright protection of digital information products. As the pivotal techniques correlative to above issues, the coding technique and digital watermarks of multimedia data attract a lot of researchers. Digital watermarking technique is a branch of information hiding. In recent years, research on information hiding techniques including digital watermark has made great progress and its range of application has been expanded gradually.After traversing the information hiding technique and the image coding system of JPEG2000, three information hiding algorithms integrated with JPEG2000 are proposed. The first scheme is a new region-of-interest (ROI) image coding method in which the information hiding technique is utilized. Image coding with regions of interest is one of the important features of JPEG2000. After analyzing the two ROI coding methods of JPEG2000 standard, their shortcoming is pointed out, and then a novel ROI image coding method with utilizing information hiding technique is proposed. In this scheme, some coded information of the background is embedded into the redundant bits of the ROI coefficients. The relative quality of ROIs and background can be adjusted by changing the quantity of embedded information. The second scheme is a robust wavelet-based dual watermarking algorithm for copyright protection of the JPEG2000 coded images. Attack on digital watermarking system destroys different part of the watermark information in various degree. In virtue of the mutliresolution characteristics of wavelet analyzing, a reference watermark is utilized to adjust the reliability of different fractions of primary watermark for reducing the influence caused by the attack. The third scheme, integrated with JPEG2000 baseline system, is an image data recovery technique based on information hiding. Firstly, the wavelet coefficients are modified non-linearly before the quantization stage. Then the relative redundancy of every wavelet coefficients is estimated. The intensity of every embedded point is <WP=5>adjusted image-adaptively according to the estimated redundancy. Finally, the most important part of the code stream is chosen as hiding information that is embedded into high-frequency components of the image. So the unequal error protection scheme for the code stream is realized.更多还原