简介:In2011,Chanproposedanimageauthenticationmethodbyproducingtheparitycheckbitsfrompixelswhosebitshavebeenrearranged.Duetothisrearrangement,thevalueofthemost-significantbitofeachtamperedpixelcanbedeterminedaccordingtoitsparitycheckbits.Withthehelpofthemost-significantbitofthepixel,thepixelcanberecoveredbyselectingtwopossible(7,4)Hammingcodewords.However,ifthedistancebetweentwoHammingcodewordsiswithinacertainrange,incorrectselectionmayoccur.Chan'smethodaddedoneadditionalbittoindicatethecorrectone.Itistrivialthatthismaydegradethequalityoftheauthenticatedimage.Inthispaper,wegroupfourmost-significantbitsintodifferentgroupstoformamappingcodebookandthemappingcodebookisusedtoproduceauthenticationdatainsteadofthe(7,4)Hammingcodebook.Theexperimentalresultsshowthattheproposedmethodhasagreaterabilitytorecovertamperedareas.