Research And Application Of Digital Watermarking Based On Chaos

With the rapid development of computer and network technology, the acquiration of digital multimedia information is becoming more easily, meanwhile, it is also more easily suffer the attacks such as illegal copying, fabricating, tampering, infringement etc, the conventional safety precautions which based on the cryptology did not have the ability equal to their ambition. In order to protect the digital product itself security as well as the owner's benefits, people put forward the digital watermarking technique. Digital watermarking is a technology which with the precondition of having no affection to the quality of the digital product, embedding the secret information into the digital product which can't be seen to attain the protection of digital product. Generally, it possesses three basic characters of imperceptibility, robustness and security.Digital watermarking technique, which embeds special information into digital products, is a new method for copyright protection. With the help of digital watermark, we can prove the originator's owner to digital products that he creates, and the watermark can be the proof of authentication and prosecuting illegal copyright infringing. Basically, there are two common methods of digital watermarking technique: spatial domain methods and transform domain methods. Spatial domain methods are simple, but they are highly vulnerable to even small cover modifications. In many cases even the small changes owning to lossy compression systems may yield to total information loss. Transform domain methods hide watermark information in the significant areas of the host image, so they are more robust to attacks, such as JPEG compression , noise contamination, cropping, zoom and circumrotate etc. In fact, these kinds of algorithms are not only robust to various signal processing but also remain imperceptible to human sensory system. There are three main transform domain methods: the DFT, the discrete cosine transform (DCT) and the discrete wavelet transform (DWT). The paper will focus on the wavelet domain, the major research works in this article are as follows:Firstly, the paper makes a comprehensive introduction about the algorithms of digital watermarking which based on wavelet transform. At first the background, the development and the algorithm's actuality of digital watermarking is introduced, dissertate the digital watermarking about the basic concept and character, generic model, typical algorithms, classification, application domain, attack analysis and evaluation of performance are also introduced.Secondly, elaborating the theory of chaos and its application .Making a simple introduction about chaotic technical and the Logistic chaos model based on the two-dimensional chaos mapping watermark image.Doing careful research on digital watermark algorithm based on chaotic model. Put forward a novel digital watermark algorithm based on chaotic maps. Different from most of existing chaotic watermarking schemes, two chaotic maps are employed in our scheme to improve the security. Selecting random position to embed the watermark. The watermark is extracted blindly. Simulation results demonstrate that the watermark generated with the proposed algorithm is invisible and the watermarking scheme is robust.Lastly, in view of the research results, elaborating the definition about discrete wavelet transform and its characteristic. This article proposes a chaos-based robust wavelet-domain watermarking algorithm. In contrast to this conventional approach, we apply the wavelet transform only locally. We transform thsubimage, which is extracted from the original image, in the frequency domain by using DWT and then embed the chaotic watermark into part of the subband coefficients. Simulation results demonstrate that the algorithm is feasible.Plentiful emulation experiments show that the algorithm ensures the watermark's imperceptibility and robustness, and is also robust to familiar image processing such as JPEG compression, noise contamination, cropping, zoom and circumrotate etc. Finally, we review the entire work, and make the expectation of the direction for the future research of watermarking.