Based On Semi-fragile Watermarking Image Content Authentication And Recovery

With high development of computer and Internet technology, digital information has provided us with great convenience to acquire information and communicate with others. Meanwhile, the rights and interests of the owner of the multimedia information and the legal user is violated. The issue of protecting the copyright has been placed high emphasis on it. The digital watermark technology, which serves as a valid way to protect the copyright, has received more and more attention.Since the multimedia information has always been transfered through the Internet. And it is inevitable to be changed by signal processing. The authentication of image content has become the most pressing problem and the central issue of academic field. The semi-fragile watermark has been becoming the hot spot. Until now, although there have been so many semi-fragile watermarking algorithms, those methods are always concerning about the embed and the detect watermark. There are soldom semi-fragile watermarking algorithms about location and recovery of the tampered images. The main content of this paper is the authentication and recovery based on the image content., and finally propose a feasible plan.In the first place, the thesis introduces the basic conception of watermark technology, including definition, model, classification, characteristic, application, principle, attacking methods, some typical kinds of watermarking algorithms, and giving simple introduction of two popular compression algorithms, and so forth. In the second place, the paper emphasizes on the wavelet theory. Finally, by simulation experiments and improving of two classical authentication and recovery methods to propose a new watermarking method base of the 2-D discrete wavelet transform. The primary coverage is discussing below:1. By analysing the Tien-You Lee's algorithm and its simulation experiments, discover the shortage and then improve it.2. By analysing the Min-Jen Tsai's algorithm and its simulation experiments, discover the shortage and then improve it.3. Propose a watermarking algorithm of authentication and recovery of image content based on the 2-D discrete wavelet transform. The effect of location and recovery of the tampered region is good, and the PSNR value is improved through the simulation experiments.