Research On Robustness And Imperceptibility Of Multimedia Digital Watermarking

The characteristic of easy copy and prevalence of digital media has been causing more and more problems. and then technology of infomation hiding offers an effective method to solve these problems. At present, since digital watermarking is the focus in society and academe, this paper does a deep research on robustness and imperceptibility of digital watermarking for multimedia. After make a deep research on robustness and imperceptibility of digital watermark for multimedia in this paper, the author figures out six creative points in this dissertation as following: (1) Making use of the DFD of software engineering to construct a union architecture of general watermarking system which describes clearly the essential concept of a lot of watermarking system. (2) The paper presents a new conception——zero watermarking, a novel kind of watermarking concept., and design two practical zero watermarking system based on the concept of watermarking, Especially, the zero watermarking system based on high-order cumulant successfully combines watermarking system with high-order cumulant, an advanced signal processing tool. (3) Applying successfully the theory of harmonics retrieval into watermarking system. (4) While chaos theory is applied to Generate Algorithm module in general watermarking system, this paper successfully applies the weak signal detection algorithm of chaos to the Revert Algorithm and Compare Algorithm of watermarking system, As far as now, there has been no correlative publication appearing. (5) Design a kind of robustness audio watermarking algorithm by using the steady positive-negative sign of DC coefficient in DCT field. (6) According to psychoacoustic model, a sort of subjective measurement-DMOPM for measuring the distortion of watermarking audio system is presented in the paper. This dissertation consists of eight chapters. In chapter one, start from information security to discuss, introduce information hiding, and distinguish between digital watermarking and steganography, introduce some application of digital watermarking and several characteristics associate with these applications. At last, contribution and architecture of this dissertation is given. Chapter two introduces generic theory model of embed digital watermarking, describes general architecture of watermarking system using DFT diagram and set a consistent expression & term used in this paper; Sum up all sorts of benchmark about digital watermarking, including subjectivity and objectivity. To show up the application environment, a standard secure watermarking identification system called IMPRIMATUR is described. Finally, some signal processing knowledge used in the watermarking system is presented. In chapter three, zero watermarking as a new concept is presented in virtue of the former research. Theoretically, zero watermarking resolves the traditional contradiction between robustness and imperceptibility. In this chapter, two kinds of zero watermarking algorithms are described. One is the zero watermarking based on DCT domain, the other is the zero watermarking based on the high-ordercumulant. Simulation results indicate that both of zero watermarking algorithms have excellent robustness. Chapter four analyses the signal component of EW (Extracted Watermark). According to the expression of EW, the method how to combine harmonic retrieval with watermarking system is found. After introducing how to transplant harmonic retrieval algorithm into Revert Algorithm and Compare algorithm, the harmonic retrieval algorithm is discussed particularly. Simulation results prove that watermarking system based on harmonics retrieval has excellent robustness. In chapter five, System of Duffing chaotic oscillator is introduced, then, the principle of detecting the weak signal using Duffing oscillator bifurcation is expatiated. Chaos theory is successfully applied to the watermarking system by considering EW as detecting signal to. Then, through improving the Cox image watermarking algorithm, we design a watermarking system based on chaotic bifurcation which has better robustness and imperceptibility according to simulation results. Chapter six presents a new robustness audio watermarking system which considers the steady positive-negative sign of the DC coefficient in DCT domain as a sort of invariable digital characteristics to embed watermarking information. The reason that the new watermarking algorithm has satisfying robustness is analyzed in theory and proved by simulation results. What's more, the robustness of watermarking algorithm presented in this chapter is better than SMM watermarking algorithm. In chapter seven, some subjective evaluation methods of the imperceptibility of audio watermarking system are introduced, and the shortcoming of these methods are indicated, and the common SNR objective measurement is demonstrated to be an unsuitable one. Then, it is represented that the psychoacoustic model often applied to audio watermarking system is used atanother angle. Combined with psychoacoustic model, the DMOPM measurement of imperceptibility is presented to be an objective evaluation method adaptive to human subjective auditory character, which is proved by theory analysis and simulation resultsr. In the final chapter, a sum-up of the paper including the main innovation and conclusions is made out, and some promising researches are presented from various angles.