Study Of Digital Watermarking Technology And Application On The Public Security System

Digital watermarking technology is an important topic in the field of information security,which has been concerned by people all the time.The rapid development of network technology provides convenient and fast for people's lives,however,with the deepening of data on internet,the authenticity of the data has become unreal.It has brought great hidden dangers to the data era which in the people's daily life,such as data tampering,loss,transfer etc.The public security system is a special administrative system in China's judicial system,the important indicators of the public security system are security accuracy and efficiency.The main direction of my paper is the application of digital watermarking technology in the public security system,the research contents are as follows:(1)The watermark image is used two-factor encryption in order to improve the security of watermark system,position scrambling and gray-level encryption,after double encryption the gray value distribution of gray histogram is more uniform,it is provided double protection for algorithm to change the image histogram.(2)A double embedding algorithm based on Contourlet Transform is improved for copyright protection in the public security system,Through the study of decomposition coefficients for multiscale contours wave and Singular Value Decomposition,the watermark after SVD is dual embedded into low frequency coefficients of Contourlet transform and suitable directional sub bands for the watermarking extraction increasing the chance.At watermarking extraction,watermark can be extracted by the singular values of the original host image,so it is an approximate blind extraction algorithm.Finally,the algorithm simulation and experimental attack are presented,invisibility and robustness for the algorithm is improved to some extent after contrast analysis with other algorithms.(3)It improved a half fragile watermarking technique for Contourlet transform.The watermark image is a two value watermark image,the image after the Contourlet transform is chose the low-frequency coefficients to embed watermark information.In the same time,the algorithm simulation is proved to be feasible in MATLAB,and the algorithm is improved to have a good tamper localization function.(4)The algorithms can be prepared for the public security system,and the visual interface is designed by.net computer language.It can be realized some factions such as watermark preprocessing,encryption,watermark embedding,attack simulation,extraction and detection.It is hoped that these two algorithms can be applied in the judicial system(5)Finally,the paper makes a deep summary for the research of digital watermarking technology,and points out the deficiencies and improvement direction of this paper.