Research On NCG Based Digital Video Watermarking Algorithms In Transform Domain

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.