Research On The Algorithm Of Digital Image And 3D Model Watermarking

In recent years, along with the technological development, particularly popularization of computer and widespread use of the Internet, digital media and the like products have obtained fast development; circulation and transaction of the digital audio and video products, as well as other electronic publications, become more and more convenient. These new technology has brought enormous convenience to human beings. But the following problems—right infringement and piracy also become worse. So, how to implement effective copyright protection and solve the problem of information security in the network has already become an imminent research subject. Digital watermark which realizes copyright protection through effective means has been widely applied in authorization certification, copyright protection, fingerprint recognition and digital signature and so on.Under the premise of not affecting the visual quality of host, in order to reduce the possibility of aggressors' successful attack at algorithm (namely, algorithm security), and to increase the algorithm robustness to operation, this paper covers the following research work and innovations:1) To gray-level digital image, we proposed two kinds of blind digital watermark algorithms: an asymmetry watermark algorithm based on feature space decomposition and a digital watermark algorithm based on optimization space. To the former method, we first decompose feature space to the host image, and then construct full ranks of matrix's rows and columns to the embedding watermark. Using the existence property of unity matrix to full rank of matrix's rows and columns, we construct the public key, which enables algorithm to embed and extract watermark in way of asymmetry. In addition, we analyze the algorithm security from many aspects, propose theoretical analysis, and confirm them through experimental results. So to the robustness of algorithm. To the latter one, we use the method of embedding DC component of the host image in time domain, and propose the improvement algorithm, which will first carry on divide block processing to the host image, and choose the DC component of each division image as the embedding territory, making the embedding watermark have robustness to geometry attack; Then, using counter-Kronecker method, we get the embedding matrix. And through embedding matrix transformation, the embedding watermark has the least value of error energy. Thus the algorithm has robustness to such operation as compression and noise. Moreover, in order to increase algorithm security, we construct asymmetry keys, and can extract watermark without original image, with theoretical analysis and evidence.2) Regarding the copyright protection of color digital image, we propose the method of embedding watermark with the color information. Through color space transformation, the algorithm, based on its own characteristics of the color image, embeds the watermark to DC component of saturation in HIS space. When the watermark is extracted, we propose image pretreatment technology. And in order to increase the popularization of algorithm, in respect of statistics, we obtain error correction component. Through pretreatment operation, we get the error energy least projected to saturation space. With the above structure, the embedding watermark has the high robust performance.3) Regarding the 3D geometry model, the basic idea is to have the error energy, caused by various transforms of 3D model, least projected to the embedding watermark. In order to enable the embedding watermark to have robustness to the topological and geometrical transformation, we first choose the vertexes of 3D mesh, with the principle of the shortest edge among vertexes. Namely, those chosen vertexes are least influenced by topological transformation of the 3D geometry model. Then, to resist the geometrical transformation, we calculate the Mean Square Error of triangle mesh vertexes, and embed watermark to the space, which is least influenced by mean square error energy, thus the embedding watermark is least affected by geometrical attack. The result shows that our algorithm is quite able to resist the topological and geometrical attacks.