Research On Robust Watermarking Algorithms

Robust digital watermarking is widely used in multimedia content protection and correlation field, such as copyright protection, traitor tracing, copy protection and broadcast monitoring. But the technology of video watermarking hasn't been developed enough. There are still lots of problems to be solved which bring chances and challenges for study. The study of digital watermarking will emphasize the robustness and security of watermarking system.The important characters of watermarking are robustness and imperceptibility. But they are contradictive indeed. The key of this problem is how to make an appropriate Human Visual System to achieve the balance of robustness and imperceptibility. At present, the most of watermarking algorithms increase robustness of the watermarking by using the spread spectrum, the channel coding and the performance of HVS. These algorithms are robust to the commonly signal processing, but they are difficult to resist the geometric attacks such as rotation and scale. Therefore, how to solve the problem of geometric attacks in embedding and detecting is a still difficult research. Moreover, video sequence may be faced with some temporal attacks, such as frame average, frame removal, frame reconstruct and so on. So the research of robust watermarking for different application is valuable.The Contourlet transform is adopted by virtual of its advantages of a flexible multiresolution, local and directional expansion because of using contour segments. The robust watermarking algorithm in Contourlet domain (AWCD) was proposed. According to the frequency, luminance and texture characteristics of HVS, the watermark composed of a pseudorandom sequence is adaptively embedded into the high-pass subbands. The detection of watermarking is according to the neighboring coefficients, and the algorithm is blind. Experimental results show that the algorithm has good robustness against attacks and imperceptibility.According to that the balanced multiwavelets are simultaneously orthogonal, symmetric and compactly supported the watermarking algorithm (VW-BMW) is proposed based on BMW. The algorithm combines the LPM to get an invariant energy for rotation, and scaling. We embed the watermark into the energy features to achieve the robustness resist geometric distortions. The balanced multiwavelets need no prefiltering procedure and have show better prospects in application especially in computing complexity. So it can satisfy the real-time and robustness of video watermarking simultaneously.A robust and blind video watermarking (SSVW) based on Shamir's secret sharing scheme for multiusers is proposed. It divides the field of host video signal into multisegments and then splits the original watermark into corresponding number shares with secret sharing algorithm. Each share of watermark is embedded into the corresponding segment of host video signal. The computing complexity of algorithm is reduced by grouping the frame sequence. In the embedding processing, the updating of watermark shadows is periodic, so the scheme proposed can resist collusion attack. In the extract processing, the hashing function is used before watermark reconstruction to resist the cheating attack. Experiment results show that the proposed watermarking technique is robust against many signal processing especially the frame average and frame lose.