Research On Multimedia Information Digital Watermarking Algorithm

With the rapid development of the electric power information and multimedia digital technologies, a large number of digital products such as digital image, audio, video and three dimensional (3D)models are produced and used during the process of the electric power production, operation, and management. Therefore, how to protect the copyright and content authentication of digital media in open networks has been a challenging issue and also has become a hot topic in electric power system. The digital watermarking technique appears accordingly and has been regarded as a promising way to protect the information security of digital products. With the construction of the smart grid, the digital watermarking is playing a more important role in network security for electric power system.Under the framework of watermarking system, this paper takes still images and three dimensional mesh models as main research objects and presents several watermarking algorithms by incorporating the advantages of the image and graphic characteristic analysis, human visual system, pattern recognition and intelligent computing. The main achievements of this paper are summarized as follows.(1)A novel fragile watermarking scheme capable of image tamper detection and recovery with a block-wise dependency mechanism is proposed. Combining the image spatial domain local properties with human visual system, the authentication data is acquired by computing class membership degree of each image block properties, which is generated by applying k-means clustering technique to cluster all the image blocks. Then the recovery data is composed of the average intensity by truncating the two least significant bits (LSBs) of each pixel within each block. Finally, the Logistic chaotic encrypted feature watermark comprising 2-bit authentication data and 6-bit recovery data of image block is embedded into the two LSBs of each pixel within its corresponding mapping block. The experimental results demonstrate that the proposed algorithm not only achieves superior tamper detection and locates tiny tampered positions in images accurately, but also has good capability of recovering the tampered regions effectively.(2) The robustness and the invisibility are important properties in an efficient image watermarking system. Since they conflict with each other, a watermarking system is difficult to satisfy them at same time. One good scheme to resolve this dilemma is to apply intelligent computing to obtain the optimized solution. An optimal robust image watermarking method based on discrete cosine transform (DCT) is proposed. The proposed algorithm is presented that the encrypted watermark is embedded into singular values vector of the embedding block by applying quantization index modulation technique. Taking the image's characteristics of texture and luminance into account, the quantization step for each embedding block is set combining statistical model with differential evolution optimization. Compared with the original method based on DCT domain, this new approach evidently improves the performance in terms of robustness.(3) Taking 3D mesh mode differential geometry estimation into account, this paper proposes a novel mesh visual masking model for mesh watermarking references. Our measure is based on the normal computation and curvature analysis in order to the watermarking embedding strength adaptive to the local geometry characteristic of the vertex. Experimental results show that this masking model is not only suitable for different types of 3D model, but also is stable under various watermarking embedding methods.(4) In feature-based 3D mesh watermarking, we firstly detect the mesh umbilical points as feature points for watermarking embedding vertexes. Combing the designed masking model, the watermark is adaptively embedded into 3D mesh model by projecting the vertex position of robust umbilical points along the principal direction. Extensive experimental results confirm that this algorithm enhances not only the overall robustness but also the watermarking invisibility.(5) In order to realize 3D mesh model blind watermarking, the quantization index modulation mechanism is used for 3D mesh watermarking. Firstly, the 3D mesh model is transformed into an affine invariant space. Combing the designed human visual masking model, the robust watermark is adaptively embedded into the 3D mesh model. Experimental results show that the proposed watermarking algorithm can resist various mesh attacks such as additive noise, affine transform, mesh compression, and mesh filtering.(6) Because the 3D mesh model is more sensitive and complex than audio and image, a 3D mesh zero watermarking system is developed based on spectral decomposition of mesh geometry. By analyzing the characteristics of the model adjacency matrix, Laplacian operator is used to obtain spectra or pseudo-frequencies. After that, the sum of the powers of the signal over the three pseudo-frequency axis defines the power spectrum of the Laplacian of 3D model. The zero watermarking is generated by difference quantizing the intermediate power spectrum coefficients This scheme is a zero watermarking scheme so that it causes no degradation on 3D mesh quality. Besides, it has better watermarking uniqueness and can resist various mesh attacks.This paper is supported by the technology projects of the state grid corporation and the state grid information & telecommunication co.,ltd. Work in this paper owns positive effect on multimedia information security of power grid and the first award for the state grid information & telecommunication co.,ltd science development.