基于DWT的数字水印算法的MatLab实现1

DWTMatLabDigitalWatermarkingBasedonDWTbyMatlab王艳玲*WANGYanling数字水印技术是近年来图像保护技术研究领域的一个热点,本文提出了一种基于小波变换的图像数字水印嵌入算法的Matlab实现实验结果表明,该算法具有较好的视觉效果和透明性图像保护小波变换数字水印MatlabAbstractThedigitalwatermarkingtechnologyisthemostactivetopicinimageprotectingrecently.Inthispaper,adigitalwatermarkingalgorithmbasedonWavelettransformisproposed,andgiveoutheprogramofthisalgorithmbyMatLab.Theexperimentalresultsdemonstratethatthemethodpossessgoodvisioneffectandtransparence.KeywordsImageprotectingWavelettransformDigitalWatermarkingMatlab*山东电子职业技术学院济南2500141,,,,,,,DFT()DCT()DWT(),,JPEG2000MPEG4,2(),,1图1水印嵌入图像的过程3DWT3.11:,2,4;LL1,;HL1LH1HH1,n,LHjHLjHHj(j=1,2n)LLn,,,,,,,C图2一级分解各分量示意图2:WCT1wi,wi=0ci!=ci(1+aiwi)WC,C!,ai3:C!IDWT2IW与5420061图3三级分解示意图3.2MatLab%dwtclear;%loadwoman;I=X;%[CA,CH,CV,CD]=dwt2(I,!db1!);C=[CHCVCD];[length,width]=size(CA);[M,N]=size(C);T1=50;a=0.2;%forj=1:1:Nfori=1:1:Mif(C(i,j)T1)mark(i,j)=randn(1,1);WaterC(i,j)=double(C(i,j))+a*abs(double(C(i,j)))*mark(i,j);elsemark(i,j)=0;WaterC(i,j)=double(C(i,j));end;end;end;%WaterCH=WaterC(1:length,1:width);WateCV=WaterC(1:length,width+1:2*width);WaterCD=WaterC(1:length,2*width+1:3*width);IW=double(idwt2(CA,WaterCH,WaterCV,WaterCD,!db1!);%figure;subplot(2,2,1);image(I);axis(!square!);title(!!);%subplot(2,2,2);imshow(IW/250);axis(!square!);title(!!);%newmark=reshape(mark,M*N,1);%T2=60;forj=1:1:Nfori=1:1:Mif(WaterC(i,j)T2)WaterCX(i,j)=WaterC(i,j);elseWaterCX(i,j)=0;end;end;end;%PSNRforj=1:1:Nfori=1:1:MD=sum(sum((WaterCX(i,j)WaterC(i,j))^2))/M*N;end;end;PSNR=10*log10(255^2/D)end;3.3Woman(256∀256),4533MHzCPU256MBMatLab6.5Windows98图4原始图像图5嵌入水印后的图像45Woman,PSNR=35.4008PSNRPSNR30,,,,,,:[1]飞思科技.小波分析理论与MatLab实现.北京:电子工业出版社,2005[2]黄达人刘九芬黄继武.小波变换域图像水印嵌入对策和算法.软件学报2002,13[3]张晓峰段会龙.基于小波变换的图像水印嵌入方法计算机工程与应用2004,11[4]C.Walker.PersonalCommunication.MuzakCorporation,June2001[]山东电子职业技术学院计算机系副教授,学士学位,山东大学信息学院在职硕士研究生,主要研究方向数字图像处理及信息安全(收稿日期:20050816)与2006155