Research On Digital Image Watermarking Technology Against Geometric Attacks

With the development of computer technology and the popularity of Internet, digital multi-media works have been spreaded widly. These bring people many conveniences, but they bring us some large side effects. So in the early 1990's a new technology of copyright protection,digital watermarking technology comes up.Digital watermarking technology comes into being for protecting the multi-media information safety, however it faces various attacks at a beginning for appear. At present, the ability of counteracting geometric attacks hasn't completely achieved the request of application. The geometry transform attack is considered as a pivotal problem to improve the robustness of watermarking algorithm. With the development of Digit, digital watermarking is urgent to improve the ability of counteracting geometric attacks of watermarking algorithm.This paper takes static images as example. After analyzing general property and principles of watermarking, we analyze the influence of geometric attacks on the robustness of digital watermarking. A new algorithm with image digital watermarking based on DCT is proposed. The watermarking image is scrambled by Arnold transformation before it embedded in DCT. Then introduce log-polar coordinate transformation into the algorithm, which make the embedding more easier. Experimental result shows that this algorithm can be immune to rotation, scaling, low pass filtering and cutting,Then we use a new method to improve the robustness of noisy. It makes the algorithm be robust not only in resisting rotation, scaling low pass filtering and cutting, but also resisting noisy. At last the conclusion of this paper and the future research orientations are pointed out.