Based On Spread Spectrum Video Watermarking Technology

This thesis mainly studied a few popular techniques of video watermark. Though analysis and comparison of their performance, two improvement scheme on current watermark technique based on spread spectrum are presented.First, the thesis made a brief introduction on main characters, model and types of video watermark. Then it elaborate on a few popular video watermark techniques, on the basis of which the main content of study is put forward.Secondly, the thesis illustrates the design and creation of watermark signal. Taking advantage of anti-interference, anti-noise, low power spectral density of the spread spectrum, I modulate each watermark information through a pseudorandom sequence to acquire a spread spectrum watermark information. Then, video watermark solution is presented, i.e., video watermark based on spread spectrum. The thesis begins with MPEG-2compressed video standard, then it goes to the algorithm principle of the video watermark. (1) After decoding the video stream partly, embed the watermark modulated by m-sequence into the colors' direct current DCT coefficient of video's frame I. Due to the selection of partly decoding, the complexity of complete decoding and recoding is reduced, and the watermark embedding process is accelerated. (2) By considering the information inside frame and between frames at the same time, original image piece is classified according to campaign information and district complication degree. Image piece both containing the detail information and belong to moving fast area is selected to be embedded into watermark. Through this method, the position of watermark embedded could automatically adapt to both HVS and video information. Then a detailed realization solution from both embedding and imbedding sides is presented.Finally, a testing is conducted on watermark embedding, withdrawing process and it's performance under attack. Through analysis of the testing result, the thesis come to the conclusion that the improved watermark technique maintains excellent steadiness and anti-attack property against frame jumping, frame deletion, sample attack and conversion of video format.