Researches On Copyright Protection For Digital Arts Based On Digital Watermarking Technology

With the increasing convenience of the distribution of digital arts and the rapid development of the Internet, the copyright protection of digital arts is becoming more and more pressing. A watermarking system will be an effective and valuable tool to solve it. In former method, the watermark is usually the pseudo-random sequence. When detection, the result is either existing or not exist. Because e-business requires that watermark can represent some information, researches on meaningful watermarking are more essential than non-meaningful watermark. Meaningful watermark has changeful form such as string and logo, and carries more copyright information such as author, publishing company and date and etc.Aiming at the problem discussed above, a meaningful digital watermarking algorithm is presented in this paper based on widely study of the theory of digital watermarking. This algorithm decomposes and reconstructs a digital image using multi-resolution ratio of wavelet transform, analyzes the design method of compactly supported orthogonal filter, and realizes the image decomposition and reconstruction based on orthogonal wavelet. Experiments show that choosing frequency domain to embed watermarking can gain image fidelity better and have more robustness than watermarking embedded algorithm in space domain. At the same time, this algorithm takes good use of digital spread spectrum technology to embed the watermarking repeatedly. The application of spread spectrum technology can increase dimension of signal in order to improve signal power and achieve code gain. Because of increasing dimension of signal/filter, it can suffer stronger signal noise. This algorithm needs original image to detect watermarking in the process of detecting watermarking.Experiments prove that this algorithm not only give attention to the intensity of embedding watermarking but also guarantee the quality of image combining with human visual system better, and it has good robust and is available for information copyright protection for keeping meaningful watermarking intact under image processing attacks such as common noises, mean filter, sub-sample and JPEG compression etc.