Study On The Security Of The Digital Watermark In Image

As the network technique and multimedia technique are developing quickly,plenty of personal datas are transmitted and traded on network. This makestraditional copyright protection and security technique face tremendouschallenge and some difficulty.Thus digital watermark technique as aneffective protect method also develops quickly. Synchronously, thetechniques of conceal analysis and watermark attacks also get a development.So the security of digital watermark become a hotspot for research in recentyears. This paper sums up exisiting security definitions, and selects asecurity measure based on MRF(markov random field) model for images, toanalyse the security of some typical digital watermark projects in image.The experiment result shows that the security measures(it means theperformance not to be felt or detected of watermark) of the watermark projectsin DFT, DWT and Contourlet Transform are prior to that in DCT or RidgeletTransform. Then a robust digital watermark method which bases on orientationin feature point field and B-spline curve multiresolution represendtationis put forward. The experiment result shows that it not only has a goodperformance to resist attacks but also is imperceptible(qualitative).At lastit analyses the security of this method quantitatively. The measure valueshows that the method has a better security, namely it is more difficult tobe felt or detected than the watermark projects in DCr, Ridgelet Transform, DFTand DWT. Also this paper observe the relation between security value and PSNRvalue by experiment.