图像与视频水印技术的研究

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1、Y9538乏3後旦大学学校代码：10246学号；032021032硕士学位论文图像与视频水印技术的研究院系(所)：僮皇型堂量王垂堂堕名：塞谨骚AbstractDigitalwatermarkingtechnologieshavearousedboardattentioninacademyandindustry,becauseoftheirbrandapplications，andhavebeenanadvanceddirectionofinformationsecurity．Fortheresearchbackground，applicationsofdigitalwatermarkin

2、gandthestateoftheart，wemainlyfocusedourresearchonthedigitalimageandvideowatermarkingalgorithm．Thisthesisisconcemedwithtwoimportantproblemsininvisiblewatermarking，howtoembedrobustwatermarksandhoWtohidereversiblewatermarks，Someworkshavebeencompletedasfollows．(1)Inordertoimproverobustness，amultibiti

3、magewatermarkingalgorithmwasproposed，whichcombinedspread—spectrumtechniquewithDCcoefficients．Inthisalgorithm，imagerelatedwatermarkswerespreadedwithGoldsequences，andembeddedintoDCcoefficients，meirintensitywascontrolledbyWatsonvisualmodel．Finally,thefavorablerelativityofGoldsequenceswasusedtorecove

4、rwatermarks．Experimentalresultsshowedthattheembeddedwatermarkscanberobustagainstgeneralimageprocessingandgeometricalattacks．(2)Inordertoincreasepayloadandrealizereversiblerecoveryofcoverimage，ahighcapacity,reversibledatahidingmethodusingwaveletcoefficientsexpansionwasproposed．Themethodused2Dinteg

5、erwavelettransformstogainredundancyfromhigh—frequencysubbandsofimage，anddirectlyhidedwatermarksinwaveletcoefficientsbyLSBexpansion．AthresholdTwasadjustedadaptivelytopreventgrayscalefromover／underflow,andflagbitswereembeddedtOenabledecoderidentifythehiddenlocation．Finally,multilevelembeddingmethod

6、wasusedrecursivelytoachievehigherpayload．(3)Forthecopyrightprotectionandauthenticationofdigitalvideo，apyramidvideowatermarkingalgorithmwasproposed，whichadoptedMPEG一4SPcompressiontechniqueandimagewatermarkingmethod．ThealgorithmembeddedrobustwatermarksintoDCcoefficientsofI-VOPandhidedfragilewaterma

7、rksinmotionvectorsofP-VOP．Experimentalresultsshowedthatthealgorithmhasgoodperformanceonrobustness，invisibilityandimplementation．Finally,wedesignedadigitalwatermarkingsystem．Keywords：DCcoefficients，Goldsequences，Integer