The Research Of Private Watermarking And Zero-Watermarking In Fourier Domain

Digital watermarking is a new measure of digital media protection, which is the process of embedding hidden messages within digital media such as text, images, video and audio to protect copyright. The hidden messages could be copyright information or secret messages. At the same time these messages have a very little influence on host media and have specific restore methods. These messages should be invisible to illegal receivers. With the global informationizing and ecommerce boosting, the requirement of the copyright protection becomes more and more urgent. Under this condition, the watermark technique is put forward and becomes one of the research hotspots in recent years. The goal of this paper is to research private watermarking and zero-watermarking schemes in Fourier domain. Firstly, the development and status of watermarking has been proposed. Secondly, some basic concepts, theories and main knowledge for the digital watermarking technology are described. Thirdly, a private image watermarking scheme based on Fourier transform is proposed. This scheme caculates an invariant centriod of the image and use it as the origin of log polar mapping. Then 2-D DFT is performed on the LPM image. And then the amplitude of intermediate frequency is used as the watermarking imbedding domain. The watermarked image is robust to geometrical attacks and signal processing attacks. Fourthly, an audio private watermarking scheme based on Fourier transform is proposed. This scheme makes the best of human audio system and embeds watermark into the phase of audio signal after FFT, which is simple and robust to some kinds of signal processing attacks. Then an audio zero-watermarking scheme based on Fourier transform and human audio system is proposed. This scheme needn't to modify the data of original audio signal. This scheme ensured the imperceptibility of the watermark and is robust. It solved the contradiction between imperceptibility and robusticity of audio watermarking. Lastly, several directions of development of digital watermarking at next stage are proposed.