Semi-watermarking Algorithm For Tampering Detect In Document Images

The digitalization of the Document paper facilitates the processing, distribution and storage of the documents information while enhances the efficiency and accuracy of information presentation. But the undesirable side effects are obvious: the unauthorized redistribution of the copyrighted multimedia data without loss of fidelity. Intellectual property protection is one of the most pressing concerns for content creators and owners who distribute and deliver their content in the Information Era. Digital watermarking, which originated from cryptography, provides a novel way for the protection of intellectual property rights, and becomes a hot spot in the research field of multimedia data security in recent years.The technology of Digital watermarking has been made great development. A practical watermarking system is often required to show its robustness, when doing with the normal operation of the image (such as image compression), and vulnerability with the malicious attack. This is just the problem that semi-fragile watermarking will solve with.In this paper, we proposed a semi-watermarking for content authentication of documents image, we can location the tampered region for the images. In this algorithm, the watermark are generated based the document image texture in DCT domain, the watermarking system is blind and image authentication can be finished without exterior watermark. At the last part of the paper, trials indicate the effective of the algorithm, this watermarking sys is sightless, for jpeg loss compressing, the watermarking is robust, for image modification or tampering, and the watermark is fragile.The main works are as follows:(1)To deal with the space domain and frequency domain of the Document Image in statistical analysis(2) Studies on the choice points of the frequency-domain image, showing that the low-frequency part of the frequency domain is fit for the watermark embed, while middle and high-frequency not(3) Present a new semi-fragile watermark embedding algorithm, which is a kind of self-embedded digital watermarking algorithm. The generation of watermark is related by the characteristics of the document image.(4) Discuss the security of the watermark embedding algorithm. It is necessary to get the information, including the frequency point of the watermark generation, the frequency point of the embedded watermark and the compression quantified Coefficient, through the process of watermark detection. And the information constitute a common key watermarking system space with high security(5) Do the Watermark attacks experiments, and through the experiments'data shows the semi-vulnerability of the algorithm...