The Application Of Digital Watermarking Forensic Technology On Police Mobile Wireless System

Digital watermarking is a new cross-discipline which develops rapidly in recent years. It has become a research at the front in information security field. This thesis studies the digital image watermarking technology and its application in image forensic.The basic concepts and theories of digital watermarking technology are analyzed and summarized in this thesis. On the basis of the current digital watermarking algorithm, this thesis has analyzed and researched some typical frequency domain algorithms, and designed two kinds of algorithms. Firstly, the thesis designs a better robust digital watermarking algorithm. The frequency domain algorithm adopts the common and information- rich gray level image as a watermark, which achieves the collaborative advantages of combining the DWT and DCT. Secondly, on the basis of the frequency domain algorithm, a valid robust blind image watermarking algorithm is designed. This algorithm in extracting of the watermarking does not require the original carrier image and the original watermarking image. It has robustness for the noise and commonly used image processing and good invisibility of watermarking, and the greater significance and practical value.In order to realize the image information forensic on Police Mobile Wireless System, Considing its own characteristic of watermarking, because of digital watermarking images and the original data can not be separated. It may undergo some routine handlings and will not be removed. At the same time it can embed a large number of secret information in the original image data. So it can be applied to the digital watermark image retrieval technology, which improves traditional self-image content-based retrieval to realize the additional specific information retrieval. It provides the witness for legal and achieves the value of digital watermarking technology.The results of the study and experiments in this thesis show that the digital watermarking algorithm has good robustness, which based on the frequency domain; at the same time the valid blind watermarking algorithm also has practical value, which can combine digital watermarking own characteristics specific to their application on the actual project to achieve specific information retrieval and forensics application value.