Research On Information Hiding And Fragile Watermarking Of Digital Image

Along with the development of the computer network, multimedia and information science, problems brought by copyright protection of digital media have become more and more serious. Techniques of information hiding and digital watermarking have become important solutions. This paper has mainly done research on fragile watermarking technique which is used for image content authentication and integrity protection and communication system based on information hiding and digital watermarking techniques.This paper has firstly introduced the developing condition about information hiding and digital watermarking techniques, especially digital fragile watermarking technique, and also forecasted the future trend by analyzing the condition of these techniques throughout the world. Secondly, this paper has introduced the relevant basic knowledge of information hiding and digital watermarking techniques, and then proposed two fragile watermarking algorithms in view of problems of image content authentication and copyright protection. The first algorithm is watermarking algorithm based on singular value space decomposition which can not only detect but also locate changes in images. The algorithm has adopted a method which divides the original image into blocks for the location problems of geometric attack. In view of the detection for original image operation, it proposed a kind of feature space decomposing method. The algorithm can be robust for some operations which are scale-limited and intensity-limited by choosing coefficients and constructing extracting matrixes, and it can implement the blind detection too. The second one is watermarking algorithm based on discrete Fourier transform (DFT). It combines DFT and features of digital images, and implements the frangibility by embedding the watermarking into high frequency part. This algorithm also implements the change location by processing block by block and increases security by blind detection. The frangibility, security and location ability of the two algorithms are all validated by computer simulations. In the end, this paper has implemented a secure communication system using techniques of information hiding and digital watermarking, and brought up the system model and implemental methods. This system has passed the validation by computer simulations.