Video Digital Watermark Research And Applications

This dissertation introduces the basic concept of digital watermarking at first. At the same time, the key technology of mpeg4 and video digital watermarking are analyzed.Afterward, this dissertation brought forward the algorithm of mpeg4 video watermarking based on DCT and the algorithm of video multi-watermarking based on motion vectors, which were designed and analyzed to their outcomes detailedly. In the algorithm of MPEG4 video watermarking , In virtue of LSB algorithm, the watermarking is permuted and is embedding DCT coefficients of frame I , which is very realtime and robust. When embedding and distilling the watermarking, the video needn' t be decoded completely. So it can advance the speed of operation and improve the performance of RealTime. In addition, a method of video multi-watermarking based on motion vectors is designed and realized elaborately in this dissertation. The method can achieve the purpose of integrality check and authentication to video data by embedding Robustness watermark and vulnerability watermark into mpeg2 video simultaneously. Based on chaos theory, the image as watermark is encrypted. Chaos theory is one kind of the cryptology. It can be used for digital copyright protection in order to improve security. The watermark image is pre-processed by chaotic sequence and magic permutation, and then is embedded. For fragile watermarking, the value is obtained after the pseudo-random sequence XOR the hash value of original data and is embedded into video later. For robust watermarking, the pseudo-random sequence is embedded into video directly. embedding and extracting watermarking algorithms are based on motion vector algorithm for fragile and robust watermarking, watermarking embedding by mending motion_residual and watermarking distilling by checking parity of motion_residual。The robustness of watermarking is intensified by embedding watermarking circularly .The circular frequency is determined by the size of watermarking and carrier. According to the robust watermarking, All rights reserved person can be confirmed and achieve the purpose of right protection. According to the fragile watermark we can determine whether the received videos are altered and achieve the purpose of integrity check。This dissertation analyzes the imperceptibility,robustness and security too. Experiments make it clear that the scheme adopted in this dissertation fully satisfies the requirements for imperceptibility,robustness and security.