【作者】 周支元；

【导师】 杨高波；

【作者基本信息】 湖南大学 ， 计算机应用技术， 2008， 硕士

【摘要】 数字水印技术是知识产权保护和安全隐秘通信的重要手段之一。视频水印是数字水印技术的重要分支,具有不同于其他载体类型水印的特点。由于数字视频在多媒体产品中占有较大的比重,且相对于数字图像水印等研究较少,数字视频水印的研究具有较强的理论和应用价值。NCG(Normed Centre of Gravity)是由德国学者Dima Pr(?)frock提出的,它类似于一个块的质心。但是,它独立于块的边界,与像素的位置无关。图像的纹理复杂度可以通过NCG的强度进行反映。本文根据视频每帧图像本身的特征,利用NCG选取特定的帧嵌入水印,以提高视频水印的透明性和鲁棒性。本文在介绍视频水印技术的发展现状及主要技术方法基础上,以常见的视频文件AVI为嵌入载体,提出了两种变换域的数字视频盲水印方案。论文的主要工作如下:1、提出了一种基于DCT和NCG的数字视频水印算法。它通过计算视频图像的NCG选定具有复杂纹理特性的视频帧,然后在选定的视频帧中,利用DCT分块变换来嵌入水印信息。该算法的优点是能抵挡剪裁、有损压缩、滤波、帧删除、帧重组等多种针对视频水印的特有攻击。2、利用数字图像的奇异值分解(SVD)的稳定性,提出了一种基于NCG和SVD的数字视频水印算法。它利用NCG的统计特性选取具有复杂纹理特征的视频帧,并利用SVD分解在DCT系数中有选择性地嵌入水印,能实现盲检测,同时鲁棒性好。上述算法在MATLAB环境下进行了仿真实验和分析。实验结果表明:算法可应用于数字视频产品的版权保护中,也可以应用在以数字视频作载体的隐蔽通信中。更多还原

【Abstract】 Digital watermarking technology is one of the important measures to protect the intellectual property protection and keep safe and secret communications.As an important branch of digital watermarking technology,video watermarking has different features as compared with other types of watermarking technologies. Since digital video is of large proportion in the multimedia products,and the research on video watermarking is relatively less,the research on digital video watermarking is of therorial significance and practical value.NCG(Normed Centre of Gravity)was proposed by a German scholar,i.e,Dima Profrock,which is similar to the gravity centre of one block.However,it is independent from the block borders,and every gray-value of the pixel has the same influence to the NCG..The texture complexity of an image can be reflected by the strength of NCG.This thesis utilizes NCG to select some frames to embed watermark information so as to improve the transparency and robustness of watermarking.After analyzing the current status of video watermarking,this thesis reseaches on NCG based digital video watermarking in transform domain.It utilizes the common AVI video as watermark carrier.The main work of this thesis is summarized as follows:First,a video watermarking algorithm based on DCT and NCG is proposed. After caculating NCG in the video images,the video frame with complex texture features has been selected,into which the watermarking information is embedded with the changes of the DCT blocks.The advantage of this algorithm is to resist the attacks targeted at video watermarking from cutting,lossy compression, filtering and so on.Second,a NCG and SVD based video watermarking algorithm is proposed. By utilizing the features of NCG,the video frame with complex texture features has been selected,into which the watermarking information is embedded by decomposition of SVD in the DCT coefficients.This algorithm can realize the blind detection and achieve excellent robustness. The above algorithms have been experimented with MATLAB.The experimental results demonstrate that these algorithms can be applied in copyright protection and information concealment,and can serve as effective measures to protect the intellectual property rights of digital video products.更多还原