A Research And Its Realization Of Digital Watermarking Algorithm Based On Wavelet Transform

With the rapidly development of the technologies of computer and communications, the transmission of digital multimedia becomes more and more convenient, at the same time, the pirate cases become more and more. For the sake of copyright protection, men have researched the digital watermarking widely and deeply. The theory of wavelet transform is a new branch of mathematics appeared in recent years, because of its excellent partial speciality; the methods of digital watermarking based on wavelet transform have become hotspot of researching.In this paper, I do my main research as the process of watermarking embeding and recovering, and then develop a new watermarking algorithm based on DWT and DCT, the main research of this paper as followings:(1) I expatiate on the main theory of wavelet transform and typical algorithms of digital image watermarking, and give the detailed steps of these digital image watermarking algorithms.(2) The DWT watermarking algorithm and DCT watermarking algorithm and DFT watermarking algorithm are realized by computer programming, and then I compare the capability of these algorithms, the comparation includes six items, which are occultation ability & anti-noise ability & anti-compress ability & anti-filter ability & anti-cutting ability & anti-rotation ability. The contrast experiment shows that DWT digital watermarking algorithm and DCT digital watermarking algorithm both have excellence capability, and their advantages and disadvantages are reciprocal.(3) The reasons of DWT digital watermarking has low ability of anti JPEG compress and DCT digital watermarking has low ability of anti JPEG2000 compress are analyzed farther. Inverse color and position excursion appear in the experiment, the reasons of these phenomena are analyzed farther.(4) By referencing some digital image watermarking algorithms based on DWT and DCT, I develop a new digital image watermarking algorithm in allusion to the disadvantages of DWT algorithm and DCT algorithm, at the same time, the advantages of DWT algorithm and DCT algorithm are used fully.(5) The new digital watermarking algorithm based on DWT and DCT is realized with computer programs, and the contrast experiment is done. The result of experiment shows that the new algorithm has excellent ability in both anti JPEG compress and anti JPEG2000 compess, and its abilities of anti-cutting & anti-rotation are improved greatly, and the phenomena of inverse color & position excursion are improved thoroughly, at one time, the other abilities of this algorithm are holded. The experiment shows that the new digital image watermarking algorithm based on DWT and DCT is an effective method with excellent capacity.