光学信息变换技术在图像加密及数字水印中的应用研究

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1、分类号UDC密级学号2151220028硕士学位论文光学信息变换技术在图像加密及数字水印中的应用研究周贝学科门类：工学学科名称：计算机应用技术指导教师：隋连升副教授申请日期：2018年4月AbstractI西安理工大学硕士学位论文referenceimageisconstructedofsignificantblockschosenfromthegrayscalehostimagebyevaluatingvisualcharacteristics.Threecomponentsofthecolorwatermarkimagearecompressedbas

2、edoncompressivesensing,andthecorrespondingresultsarecombinedtoformthegrayscalewatermark.Thefrequencycoefficientsofthegyrator-transformedgrayscalewatermarkimagearefusedintothefrequencydataofthegyrator-transformedreferenceimage.Thefusedresultisinverselytransformedandpartitioned,ande

3、ventuallythewatermarkedimageisobtainedbymappingtheresultantblocksintotheiroriginalpositions.Theschemecanreconstructthewatermarkwithhighperceptualqualityandhastheenhancedsecurityduetohighsensitivityofthesecretkeys.Simulationresultshaveverifiedthefeasibilityandtherobustnessagainstat

4、tackssuchasnoiseandocclusionattack.Third,anopticalimagewatermarkschemeusingghostimagingtechniquehasbeenimprovedinthegyrator(GT)domain.Inthisscheme,thewatermarkalgorithmhasbeenimplementedundertheframeworkoftwo-layerconfiguration.Inthefirstlayer,thewatermarkisencodedintoaseriesofmea

5、suredintensitiesbyusingcomputationalghostimaging,whichisusedtoformaninterimimagewiththesamesizeofthehostimage.Inthesecondlayer,theGTtransformisappliedtohostimageandinterimimage,respectively.Thetransformedinterimimageisembeddedintothetransformedhostimagewithaweightedfactor,andthent

6、hewatermarkedhostimagecanbeobtainedbyusingtheinverseGTtransform.Thefeasibility,effectivenessandrobustnessagainstdifferentattacksoftheproposedschemehavebeenverifiedwithsimulationresults.Keywords:Imageencryption;Chaoticstructuredphasemasks;Humanvisualcharacteristics;Computationalgho

7、stimaging.II目录目录1绪论...........................................................................................................................................11.1选题背景和意义.............................................................................................................11.

8、2图像加密研究及发展现状.....................