Research And Realization Of Robust Watermarking Schemes For Digital Images Based On DCT Domain

Piracy and malicious falsify not only can cause economic losses, but also lower creationenthusiasm of the original. For this new severe challenge, digital watermarking technology as animportant branch of information hiding technology draw more and more attention from peoplebecause of its effective protection for copyright, and watermarking technology is developingrapidly. Digital watermarking technology is effective technology of digital product copyrightprotection and data security maintenance. It combines with digital image processing technologyand the ancient hiding technique and embeds the mark that is watermarking into the digital audio,images, video, text and other multimedia information using digital signal processing method.The embedded watermarking information is aimed at proving the ownership of product, theintegrity, authenticity, reliability of information, tracking piracy, providing other additionalcontent and so on, therefore, digital watermarking can be used to the strong evidence ofdetermining and punishing the illegal invasion stealing behavior.In this paper，the basic principle of information hiding technology, information hidingtechnology characteristics, classification and application of information hiding technology havebeen introduced briefly; then the research history, the model and principle, characteristics andclassification, the application, the present research situation and the development of the digitalwatermarking technology that is as one of the two important branches of the information hidingtechnology are illustrated systematically. As the basis of the paper’s research, it is necessary toexplain the common algorithms, the pretreatment technology, the perception model, the attacksand performance evaluation, and commonly used software of the digital watermarkingtechnology. In addition, in order to strengthen the paper intelligibility, basic theory including thediscrete cosine transform, image color model and program design using MATLAB is reviewed.This paper proposed two digital watermarking schemes, those are image watermarking schemebased on adaptive quantization index modulation in DCT domain and the robust watermarkingscheme for RGB anaglyphic3D images. And the second scheme includes anaglyphic3D images watermarking scheme based on the spread spectrum (SS) and anaglyphic3D imageswatermarking scheme based on the adaptive DM with the improved Watson perception model.This definite research content and innovation achievements are as follows.On the basis of research for quantization, this paper proposes a new adaptive QIM(Quantization Index Modulation) watermarking scheme based on spread transformation. Carryon spread transformation before embedding watermarking; extract vectors from the carrier image;calculate the projection vectors in intermediate frequency component and do projectiontransformation; carry dither modulation on the projection data at last. In the process of dithermodulation, the adaptive quantization step size is adopted to embed the watermarking accordingto the characteristics of image. The minimum distance detection was used to extract thewatermarking without the original image, so the extraction is blind. The simulation testsincluding watermarked image fidelity and the robustness of the watermarking scheme have beencarried out. Experimental results are compared and simulations and analyses of the brightnessattack are done. Experimental results show that the proposed watermarking scheme has verygood invisibility; they are robust to scale, shear, Gaussian noise, salt and pepper noise, JPEGcompression, brightness attack; so the watermarking scheme has good robustness. Therefore, thescheme meets the demand for invisibility and robustness. The simulation results of themultiplicative and additive brightness attacks show that watermarking scheme against additivebrightness attack is superior to the additive brightness attack. That maybe caused by thenon-linear change of image luminance component. The future work will be devoted to improvethis defect.Two kinds of anaglyphic3D digital images watermarking schemes are put forward. Thefirst scheme is anaglyphic3D images watermarking scheme based on the SS; and the spreadspectrum digital watermarking technology is applied to3D images. The experimental resultsshow that the watermarked anaglyphic3D images have very good fidelity, and the PSNR valueis as high as41.8847dB. And that the scheme has good robustness to many kinds of commonsignal processing or attacks on the premise of such a high fidelity.The second is anaglyphic3D images watermarking scheme based on the adaptive DM withimproved Watson perception model. The improved slack is used for anaglyphic3D imageswatermarking technology to calculate adaptive quantization step size. The improved Watson perception model can well solve the slack that is not linearly change as amplitude scale. Theresults show that the watermarked3D images have both satisfactory fidelity and very goodrobust performance. BER values of extracted watermarking after the attacks of Gaussian noise,salt and pepper noise, JPEG compression, brightness change and numerical scale is less than0.07. When the watermarking schemes have the same image fidelity, namely fixed PSNR value,and the same color base decomposition method is adopted, the sensitivity of two watermarkingschemes and watermarking scheme with unimproved Watson perception model against theattacks such as Gaussian noise, JPEG compression, constant brightness change and thenumerical scale is tested. The experimental results show that properties of the proposed schemebased on adaptive DM with improved Watson perception model are improved. The scheme basedon the SS has stable performance for the JPEG compression attack and performance for theGaussian noise, numerical scale is poor; it is not sensitive to the microvariation constantbrightness change attack. The scheme based on adaptive DM with the improved Watsonperception model is not sensitive to constant brightness adjustment and numerical scale attackbut sensitive to the Gaussian noise and JPEG compression. The two schemes have bothadvantages and disadvantages, so the future work will combine them such as the switch tablemethod. And that is the paper’s future research work to carry out.Moreover, in this paper, the scheme DM-mW-3d was compared with literature [93] andliterature [94]. The experiment results show that the improved watermarking scheme in thispaper has a satisfactory effect for Gauss noise, numerical scale and brightness change. Andespecially, the sensitivity of Gaussian and brightness attack significantly lower than the twoliteratures.In general, the two watermarking schemes contribute to protection of digital images’copyright, especially for anaglyphic3D images which are the new digital media. This thesisresearch has certain breadth and depth, and some results have been published in the domestic andinternational famous journals.