Research On Digital Watermark Algorithm For DTV Copyright Protection

With the rapid development of digital television (DTV) technology and multimedia technology, people can share the digital resources more conveniently than ever before. But meanwhile, the copyright protection of multimedia information becomes a serious problem. As a potential and effective way to solve this problem, digital watermarking becomes a very active research area of signal and information processing, and it has attracted considerable attention in the past two years.Digital watermarking is a technology that embeds a signal (the watermark) into a digital image or video sequence that allows one to establish ownership, identify a buyer, or provide some additional information about the digital content. This thesis is about the research on digital image watermark technique and digital video watermark technique. It focuses on DTV multimedia copyright protection by embedding watermark information in the pixel domain or in the frequency domain.This paper includes two parts:The first part is about the research on invisible and visible watermark for YUV digital image. It is very necessary to be familiar with the YUV,BMP file format and the conversion between them. To make sure the watermark information is stable after the format conversion, the robustness of the algorithm is the key point. For the visible watermark technology, an algorithm is proposed with the image data which stands for the owner of the digital product added to the original color image. The algorithm is direct,flexible,and useful in some case.The second part proposes a digital watermarking algorithm for the MPEG-2 video based on DCT transform by modulation of corresponding DCT coefficients. Based on the MPEG-2 video standard and human visual system (HVS), this paper proposes a useful watermarking scheme especially for the application of digital watermarking in the MPEG-2 video. It uses the DC and AC coefficients after DCT to embed the watermark image. In the conclusion part, it analyzes the experimental results. The length of the video file,the objective quality and the subjective quality are compared and discussed between pro-embedding and after embedding.The work is helpful for having deeper knowledge in digital watermark technology and is meaningful for the research on the multimedia copyright protection. At present, these solutions have been used to protect the definition testing images and sequences of HDTV (High Definition TV),SDTV (Standard Definition TV).Other work is also presented in the paper: MPEG audio(MPEG-1 and MPEG-2)volume adjusting solution. It is realized by changing some grammar section in the audio stream without decoding it completely. So far, the platform is built successfully, and can be integrated into"multi-media edit integrative work station"which is developed by the whole lab.