Research On Robust Digital Watermarking Technology Against Geometric Attacks

Recently, the development of multimedia storage and transmission technology, especially the popularization of the Internet technology push the development of the digital media application, Many types of multimedia works such as image, video and music can be conveyed in a new way of network. These technologies bring people many conveniences, but they also bring us some large side effects, for example, anybody can get the original products of others easily, especially digital products such as images, musics and films. Someone can copy and tamper the original works arbitrarily under disagree, as infringes the author's copyright. How to protect the copyright effectively and solve the problem of information safeties on network is an urgent subject.Under this condition, as a kind of technology to solve multimedia information security problem on network, watermarking technology comes up into being. It embeds watermarks into the digital medias, then carries out the functions such as informations hiding, storing, copyright safeguarding by tracking the use of the image by detecting the watermarks. At present, watermark technology becomes a kind of effective means to multimedia copyright authentication and its integrity safeguarding.This paper takes still images as example, analusizes the inflences of geometric attacks on the robustness of digital watermark and the image itself, and finds the image watermark theory and technologies being fit for resisting the geometric attacks via theory research and experimentation testifying. It makes use of 3D wavelet transformation theory, time and frequency analysis theory, DCT transformation theory, unilateralism Hash functions encrption and Haar orthogonal function systems to make the systematic and important investigation on the robustness of digital image resisting to the geometric attacks, raises some new theory thoughts and technology projects, partly resolve the problems of mistakes on the robustness and examination of watremarks because of the geometric attacks on the digital image and implement the robust watermark technology resist geometric attacks.1. Research on estimating algorithm of image random parameters of shearing, ratation and zoomingTo the damage of geometric transformation (shearing, ratation and zooming)on the data synchronization, the geometric parameter estimating algrithm is introduced in this paper to make geometric transformation image to match the original image and implement the credible examination of watermark. Tis algrithm makes use of the ratation invariability of Fourier transformation on the edge image and difference correlation technology to exactly compute slope angle and computes 2D correlation functions to calculate comparative displacement, to gain the position of the shearing image in the original image, and to make the shaering match the orignal image. This paper adopts the space difference correlation technology to exactly estimate the parameters of the zooming image and to match orignal image. This algrithm is practical.2. The research of robust watermark technology applying the DCT transformation and unilateralism Hash functions encrption theoryThis paper introduces a kind of robust digital watermark technology resisting geometric attacks on the base of the DCT transfonnation and unilateralism Hash functions encrption theory, decides the embedding positions and embedding extent. The positions of watermark are false random sequences and for the unaccredited users it is very impossible to detect the presence of watermark. The original owner of watermark can assure the safety of the watermark resisting the attacker. This algrithm applies the 8 X 8 DCT transformation technique to embed watermark into the middle frequence parts and shows excellent robustness and imperceptility. This algrithm applies the EIGFamal watermark encrption scheme and this algrithm is very safe.3. The research of robust digital watermarking algrithm against geometric attacks based on Haar orthogonal function systemThe deep research in the bridge function theory leads to that the real generalized bridge function system includes real multi-value Haar function system. The real multi-value Haar function system is a kind of self-contained generalized orthogonal function system. This paper introduces the robust digital watermarking algrithm against geometric attacks based on Haar orthogonal function system. The proposed algrithm makes the Haar orthogonal transform on the image and the significant middle frequently coefficients in the transformation matrix are picked up, on the base of characteristics of the image visual system and the Haar orthogonal transform. The watermark is adoptively weighed to the middle frequently matrix with zero watermark technique. This algrithm shows excellent qualities of resisting attacks and implement favorable robustness andvalidity.4. The research of robust digital image watermark algrithm on the base of 3D wavelet transformationThis paper introduces a kind of 3D wavelet transformation digital watermark algrithm on the base of the disperse wavelet transform and there-dimensional wavelet transformation on the video sequences. This algrithm splits the original image to a sense of image videos and the watermark is adaptively weighed to the different positions of the middle frequency region in the two-dimensional wavelet transformation of image videos and makes use of haracteristics of the image theory and human visual system. The algrithm shows excellent advantage against shearing attack and can clearly detect the watermark when a majority of the image is sheared. Abundant experiments prove the feasibility of this technology and this algrithm is a new ideology and solving project without fail.5. Applying the time-frequency analysis theory, research of robust image watermark technology based on the two-dimensional Radon-Wigner transformationA robust image watermarking algrithm resisting geometric distortions in two-dimensional space time-frequency distributions domain is proposed. This watermarking is davactericed by a linear frequency change and the two-dimensional Radon-Wigner transformation is used to detect the watermark. The two-dimensional chirp signals are used as watermarks and this type of signals is resistant to all stationary filtering methods and exhibits geometrical symmetry. In the two-dimensional Radon-Wigner transformation domain, the chirp signals used as watermarks change only its position in space time-frequency distribution, after applying linear geometrical attack, such as scale rotation and cropping. The watermark thus generated is invisible and is robust to geometrical attacks. Compared with other watermarking algorithms, this algorithm is more robust, especially against geometric distortion, while having excellent frequency properties. The proposed algorithm is a kind of novel technology that has a happy future.