Digital Watermarking

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1、DigitalWatermarkingR.ChandramouliNasirMemonDepartmentofECEDepartmentofComputerScienceStevensInstituteofTechnologyPolytechnicUniversityHobokenNJ,07030Brooklyn,NY11201MajidRabbaniImagingResearch&AdvancedDevelopmentEastmanKodakCompanyRochester,NY146501IntroductionTheadventoftheIn

2、ternethasresultedinmanynewopportunitiesforthecreationanddeliveryofcontentindigitalform.Applicationsincludeelectronicadvertising,realtimevideoandaudiodelivery,digitalrepositoriesandlibraries,andWebpublishing.Animportantissuethatarisesintheseapplicationsistheprotectionoftheright

3、sofallparticipants.Ithasbeenrecognizedforquitesometimethatcurrentcopyrightlawsareinadequatefordealingwithdigitaldata.Thishasledtoaninteresttowardsdevelopingnewcopydeterrenceandprotectionmechanisms.Onesucheffortthathasbeenattractingincreasinginterestisbasedondigitalwatermarkingt

4、echniques.Digitalwatermarkingistheprocessofembeddinginformationintodigitalmultimediacontentsuchthattheinformation(whichwecallthewatermark)canlaterbeextractedordetectedforavarietyofpurposesincludingcopypreventionandcontrol.Digitalwatermarkinghasbecomeanactiveandimportantareaofr

5、esearch,anddevelopmentandcommercializationofwatermarkingtechniquesisbeingdeemedessentialtohelpaddresssomeofthechallengesfacedbytherapidproliferationofdigitalcontent.Intherestifthischapterweassumethatthecontentbeingwatermarkedisastillimage,thoughmostdigitalwatermarkingtechnique

6、sare,inprinciple,equallyapplicabletoaudioandvideodata.Adigitalwatermarkcanbevisibleorinvisible.AvisiblewatermarktypicallyconsistsofaconspicuouslyvisiblemessageoracompanylogoindicatingtheownershipoftheimageasshowninFigure1.Ontheotherhand,aninvisiblywatermarkedimageappearsverysi

7、milartotheoriginal.Theexistenceofaninvisiblewatermarkcanonlybedeterminedusinganappropriatewatermarkextractionordetectionalgorithm.Inthischapterwerestrictourattentiontoinvisiblewatermarks.Aninvisiblewatermarkingtechnique,ingeneral,consistsofanencodingprocessandadecodingprocess.

8、AgenericwatermarkencodingprocessisshowninFigure2.Here,thewate