【作者】 明慧芳；

【导师】 杨杰；

【作者基本信息】 武汉理工大学 ， 信号与信息处理， 2004， 硕士

【摘要】 伴随着网络技术和多媒体技术的飞速发展，多媒体信息逐渐成为人们获取信息的重要手段，已成为人们生活的重要组成部分。目前，在多媒体计算机技术应用系统中，对视频图像处理有两大研究方向：一是视频图像的压缩编码；二是视频图像的实时处理和图像信息的安全。 视频图像压缩编码是解决有限的存储空间与越来越丰富的视频信息之间矛盾的需要，同时也是满足节省通信信道带宽和视频实时传输的需要。视频图像信息的安全是为了防止敏感信息轻易地窃取、篡改、非法复制和传播。信息安全主要包括信息加密技术和信息隐藏两部分，本文主要研究视频信息加密技术。 论文首先简要地介绍了课题背景和当前的研究状况，研究了视频编码模型特点，分析了MPEG-2数据结构特点和AVI视频格式的异同，在同等的视觉质量范围下MPEG-2采用有损压缩方法减少运动图像中的冗余信息从而达到高压缩比，因此MPEG-2压缩算法作为国际标准，被许多的计算机平台共同支持，较AVI视频具有更好的兼容性。在此基础上设计了AVI视频到MPEG-2视频的实现方案，并加以实现。其次，参考了一般的数据加密方法，目前图像信息加密算法主要有二大类。一是用纯密码算法加密技术，将图像数据文件当作一般的二进制数据文件进行加密。二是基于编码模型的加密算法，它是根据图像描述语言或某种空间填充曲线，对图像信息进行变换。我们采用椭圆曲线加密算法作为纯密码加密技术进行实验，发现纯密码加密技术没有考虑到视频信号的特点，加密效果不理想。 论文最后采用了置乱算法的加密思想，考虑到MPEG-2视频结构中P帧和B帧中运动向量计算的特点，提出了一种基于混沌理论的视频加密算法。利用混沌理论在MPEG-2视频的I帧中进行加密，然后通过P帧B帧分布到整个MPEG-2视频文件中。经过实验证明了这种方法对于I帧的压缩仍然具有视觉范围内很好的解密能力，即使对于P帧和B帧的压缩也有很不错的效果。更多还原

【Abstract】 With the development at full speed of the network technology and multimedia technology, the multimedia information becomes the important means that people obtain information gradually and has already become the important component of people’s life. At present, in the technological application system of the multimedia computer, there are two major researches to the video process: one is the compression code of the image; the other is the real-time processing of the image and protection of image information.It is a need of solving the contradiction between the limited memory space and more and more abundant video information that the video image compresses the code, alleviate video communication between channel and communication contradiction between the channel width in recent years and meet need that transmit in real time of video too at the same time. The protection of the image information of the video is for preventing the stealing, distorts, duplicates and spreads illegally easily of sensitive information. The technology of image information includes information encryption and information hiding two parts. The video information encryption is mainly researched in this paper.In this paper, at first, the background and the state of the subject are introduced. We study the code model characteristic of videos, analyse the characteristic of MPEG data structure and similarities and differences of forms of AVI video. The method which compresses the information of an image and the differences of images is adopted to reach the high compression ratio. MPEG compresses algorithms as the international standard, is supported together by many computer platforms now, have better compatibility than AVI video. We design the realization scheme to MPEG-2 video of AVI video on this basis, and realize. Secondly, we have consulted the general data encryption method. An encryption method based on ECC is applied on the MPEG system directly. The encryption method isn’t considered the characteristic of the video signal, regard the image data file as the general binary scale data file to encrypt. It isunsatisfactory to encrypt the result.At last, a new method based on chaos theory is considered. We test it and get a better result than the other methods we have discussed.更多还原