Digital Watermarking Technique For Color Image Based On 2nd Generation Wavelet Transform

With the booming development of multimedia technology and the exceptionalgrowing of Internet ,we can get digital information conveniently and quickly. Buthow can we protect the author's copyright and economic profits? It has becomemuch urgent to provide efficient copyright and security protection means for thedigital products. So the digital watermark technology has been put forward in recentyears.Digital watermark is invisible mark embedded in digital image, video or audiodocuments, which can be detected to protect copyright of multimedia data. Awatermark is a digital code containing information of author ID, company logo,product serial number or something else. To be successful, the watermark must beunperceivably and permanently embedded into the data, that is, after any distortionprocess, it can also be extracted to prove ownership, to recognize the identity of amisappropriator, to trace the dissemination of the data through the network, or toauthenticate the integrity of the data.In this dissertation, the application of digital watermark technology has beenstudied in the round. First, this thesis analyzed the current development status ,basiccharacters and problems of digital watermark lechnology, and discuss the generalframe of digital watermark processing system. Then, some important research resultsof watermarking are presented and the attacks towards watermarking system arediscussed. Secondly, based on the wavelet analysis theory, a deep discussion onapplication of the wavelet transform to the digital watermarking technology is given.Thirdly, from three aspect of chosen of watermark information, chosen of watermarktransform domain and transform method, and watermark hiding and detectingalgorithm, the digital watermark technology is studied in detail. Noticeable, tochoose the intuitive digital image as the watermark is a new idea in this dissertation.Wavelets have found wide applications in image processing due to the multiscaleanalysis property. In recent years, the study of wavelet transform urged its usage inimage coding. The multiresolution analysis of wavelet transform matches with thecharacter of human vision. It can give sub-bands for different levels and differentdirections of an image. The 2nd generation wavelet transform is a new method for contructing waveletsand performing wavelet transform. The work concerns with the watermarking algorithm that embed image datainvisibly into a color image based on the 2nd generation wavelet transform. Theoriginal color image is transformed into the YIQ color space. Exploiting theexcellent properties of the wavelet transform and some characteristics of HumanVisual System(HVS), encrypted watermark is embedded into the Y luminancecomponent of the YIQ in IWT(Integer Wavelet Transform) domain. As the digitalwatermarking algorithm has been transformed from spatial domain to moreadvantaged frequency domain, a novel algorithm based on wavelet transforms thatmap integers to integers is presented in this paper. Wavelet transforms match theHVS model, thus it can well balance the contradiction between transparency androbustness of the digital watermark. Because of the storing characteristic of theimage, wavelet transforms that map integers to integers will not introducequantifying error while calculate. Moreover, the experimental results have proved that the method is robustto some image process such as sharpening, JPEG2000 compression and rotation etc.The performance of the proposed watermarking is invisible to HVS and robust to avariety of signal distortions. Digital watermarking is a new technology, which refers to communication andinformation technology, image and speech processing, signal detection andevaluation, mathematics, human audio and visual systems, computer network andapplication etc. Although in recent years great progress has been made in theaspects of theory and applications there is no complete theoretical framework,...