【作者】 陈禧；

【导师】 朱冰莲；

【作者基本信息】 重庆大学 ， 信号与信息处理， 2007， 硕士

【摘要】 随着现代计算机技术和互联网技术的发展,多媒体数字作品的获取、复制和传播变得越来越容易,使得多媒体数字作品的版权日益受到严重威胁,极大地损害了作品所有者的经济利益,因此多媒体知识版权保护已经成为一个亟待解决的问题。数字水印技术作为一种新的解决版权保护问题的有效途径,近年来已成为信息安全领域的研究热点。数字水印技术是在不影响数字作品使用质量的前提下,在数字作品中嵌入不可见的秘密信息来达到对数字作品的保护,它一般具备不可见性、鲁棒性及安全性三个基本特征。在各种数字水印技术中,视频数字水印技术由于其自身的研究价值和潜在的经济利益而倍受各国学者的关注。然而相对于静止图像水印技术,视频水印技术的发展相对滞后。本文系统地综述了数字水印技术的基本概念、框架和应用领域,介绍视频水印技术的特殊性和国内外研究现状,对视频水印技术的分类、特殊性和评价基准做了详尽介绍。在此基础上重点研究基于MPEG-4的视频数字水印算法及其相关问题,主要研究工作如下:①针对本文所采用的Toral置乱方法,详细推导了其变换周期,给出了一种计算Toral变换周期的简便算法,并在VC++6.0环境下采用C语言实现了该算法。②针对目前基于纠错码水印技术不能兼顾盲检测和软判决译码的不足,提出了一种适合软判决译码的盲水印算法。论文首先在图像中验证了算法的有效性,并从理论和实验两方面讨论了算法中量化步长的取值范围。然后结合MPEG-4标准的具体情况,将所提出的算法嵌入到MPEG-4视频编解码器中。实验结果表明纠错码能较好的提高水印的鲁棒性,而软判决译码较硬判决译码能进一步提高水印的鲁棒性,同时本文算法还能很好地满足实时性的要求。③在VC++ 6.0集成开发环境下,采用C/C++和MFC开发了一款基于本文算法的水印嵌入/检测(提取)软件。更多还原

【Abstract】 With the rapid development of modern computer and Internet technology, it is more and more easy to access, duplicate and spread the digital multimedia works, which makes the copyright of digital multimedia works damaged seriously and heavily damages the benefits of the owner. So multimedia intellectual property protection becomes an urgent problem to be solved.As a new and effective approach to solve the problem of copyright protection, digital watermarking has emerged to be an active and flourishing research topic in the field of information security recently. Digital watermarking technique protects the digital works by embedding unperceivable and secret information into digital works, which has no effect upon the using of the digital works. Generally, it demands three basic characters of imperceptibility, robustness and security. In the kinds of digital watermarking techniques, researchers have paid more attention to video watermarking technique because of its high research value and potential commercial profits. However, current video watermarking technique is far beyond mature compared with the still image watermarking.This thesis systematically summarizes the concepts, framework and the typical applications of watermarking technique. It also introduces the characteristics, research status, speciality, classifications and benchmarks of video watermarking techniques in detail.This thesis focuses on video watermarking algorithms based on MPEG-4 and experiments are performed to test the effectiveness of the proposed algorithm. The main research work and contributions of this thesis are summarized as follows:①This thesis deduces the period of Toral transform in detail and proposes an algorithm to calculate the period of Toral transform. The algorithm is implemented in Microsoft Visual C++ 6.0 integrated development environment by C language.②Because the currently available watermarking algorithms based on error correcting code can not combine the blind watermark technique with soft-decision decoding technique, this thesis proposes a blind watermarking algorithm which is suitable for soft-decision and can effectively improve the robustness of watermark. The validity of proposed algorithm is tested in image and the range of quantization step in the algorithm is also discussed by deduction and experiment. Then the proposed algorithm is embedded in MPEG-4 video CODEC and experimental results show that error correcting code can effectively improve the robustness of watermark and soft-decision decoding is better than hard-decision decoding. In addition, the real-time processing demand is also satisfied.③According to the proposed algorithm, a watermark embedding/extracting software is developed in Microsoft Visual C++ 6.0 integrated development environment by C/C++ and MFC.更多还原