Image Digital Watermarking Technology

With the rapid development of Digital Signal Processing and Computer Network, the traditional media services have come into the digital age. The digital media can be duplicated and transmitted rapidly at almost no cost. All these merits of digital media bring the customers and the contents provider a great favor. But it's hard to protect the copyright of digital media by the traditional digital encryption.Digital Watermarking is a new technology for the copyright protection to the digital media in the networked environment. It can protect the copyright of digital media effectively through the detecting the watermark embedded in the media. The appearance, application, watermark system principle, classifications and attacks are outlined in this paper.The Principle of Transform Domain Watermarking and Spread Spectrum Watermarking Algorithm for digital image are analyzed in detail in this paper. And the advantages and disadvantages of Secure Spread spectrum Watermarking proposed by I.J.Cox are studied in order to develop the more effective watermarking algorithm.The followings are our contributions:1. A New Watermark Detecting Algorithm Based on Attack Character Complementarity is proposed in this paper. The new detector can improve the performance of the watermark detector by the pre-processing to the attacked watermarked image before watermarking detecting.2. A New Robust Watermarking Algorithm Based on Pixels Permutation is proposed in this paper. The scanning lines of the image are permuted randomly to balance the energy distributing of the image scanning lines, then the watermark sequence is embedded in the image with the spread spectrum watermarking algorithm to produce the watermarked image. Experiments demonstrate the new watermarking algorithm can improve the watermark capacity greatly.