基于小波变换的数字水印技术.zip

function [Iw,psnr]=setdwtwatermark(I,W,ntimes,rngseed,flag) type=class(I); I=double(I); W=logical(W); [mI,nI]=size(I); [mW,nW]=size(W); if mW~=nW error('SETDWTWATERMARK:ARNOLD','ARNOLD置乱要求水印图像长宽必须相等！') end [ca1,ch1,cv1,cd1]=dwt2(I,'haar'); [ca2,ch2,cv2,cd2]=dwt2(ca1,'haar'); if flag figure('Name','载体小波分解') subplot(121) imagesc([wcodemat(ca1),wcodemat(ch1);wcodemat(cv1),wcodemat(cd1)]) title('一级小波分解') subplot(122) imagesc([wcodemat(ca2),wcodemat(ch2);wcodemat(cv2),wcodemat(cd2)]) title('二级小波分解') end Wa=W; H=[1,1;1,2]^ntimes; for i=1:nW for j=1:nW idx=mod(H*[i-1;j-1],nW)+1; Wa(idx(1),idx(2))=W(i,j); end end if flag figure('Name','水印置乱效果') subplot(121) imshow(W) title('原始水印') subplot(122) imshow(Wa) title(['置乱水印，变换次数=',num2str(ntimes)]); end ca2w=ca2; rng(rngseed); idx=randperm(numel(ca2),numel(Wa)); for i=1:numel(Wa) c=ca2(idx(i)); z=mod(c,nW); if Wa(i) if z<nW/4 f=c-nW/4-z; else f=c+nW*3/4-z; end else if z<nW*3/4 f=c+nW/4-z; else f=c+nW*5/4-z; end end ca2w(idx(i))=f; end ca1w=idwt2(ca2w,ch2,cv2,cd2,'haar'); Iw=idwt2(ca1w,ch1,cv1,cd1,'haar'); Iw=Iw(1:mI,1:nI); mn=numel(I); Imax=max(I(:)); psnr=10*log10(mn*Imax^2/sum((I(:)-Iw(:)).^2)); I=cast(I,type); Iw=cast(Iw,type); if flag figure('Name','嵌入水印的图像') subplot(121) imshow(I); title('原始图像') subplot(122); imshow(Iw); title(['添加水印，PSNR=',num2str(psnr)]); end