DCT数字水印.docx

水印嵌入：clear all; k=20;blocksize=8; midband=[ 0,0,0,1,1,1,1,0; 0,0,1,1,1,1,0,0; 0,1,1,1,1,0,0,0; 1,1,1,1,0,0,0,0; 1,1,1,0,0,0,0,0; 1,1,0,0,0,0,0,0; 1,0,0,0,0,0,0,0; 0,0,0,0,0,0,0,0 ];message=double(imread(shan.PNG));Mm=size(message,1);Nm=size(message,2); n=Mm*Nm;message=reshape(message,1,n);cover_object=double(imread(lena.bmp)); Mc=size(cover_object,1);Nc=size(cover_object,2); c=Mc/8; d=Nc/8; m=c*d;xx=1;for j=1:c for i=1:d pjhd(xx)=1/64*sum(sum(cover_object((1+(j-1)*8):j*8,(1+(i-1)*8):i*8))); fc(xx)=1/64*sum(sum((cover_object((1+(j-1)*8):j*8,(1+(i-1)*8):i*8)-pjhd(xx)).^2)); xx=xx+1; endendA=sort(fc);B=A((c*d-n+1):c*d); fc_o=ones(1,c*d);for g=1:n for h=1:c*d if B(g)==fc(h) fc_o(h)=message(g); h=c*d; end endendmessage_vector=fc_o;watermarked_image=cover_object;rand(state,7);pn_sequence_zero=round(rand(1,sum(sum(midband))));x=1;y=1;for(kk=1:m) dct_block=dct2(cover_object(y:y+blocksize-1,x:x+blocksize-1)); ll=1; if (message_vector(kk)==0) for ii=1:blocksize for jj=1:blocksize if (midband(jj,ii)==1) dct_block(jj,ii)=dct_block(jj,ii)+k*pn_sequence_zero(ll); ll=ll+1; end end end end watermarked_image(y:y+blocksize-1,x:x+blocksize-1)=idct2(dct_block); if (x+blocksize) = Nc x=1; y=y+blocksize; else x=x+blocksize; endendwatermarked_image_int=uint8(watermarked_image);imwrite(watermarked_image_int,dct2_watermarked.bmp,bmp);xsz=255*255*Mc*Nc/sum(sum((cover_object-watermarked_image).^2));psnr=10*log10(xsz)figure(1)imshow(watermarked_image,[])title(Watermarked Image)水印提取：clear all; clcblocksize=8; midband=[ 0,0,0,1,1,1,1,0; 0,0,1,1,1,1,0,0; 0,1,1,1,1,0,0,0; 1,1,1,1,0,0,0,0; 1,1,1,0,0,0,0,0; 1,1,0,0,0,0,0,0; 1,0,0,0,0,0,0,0; 0,0,0,0,0,0,0,0 ];cover_object=double(imread(lena.bmp)); watermarked_image=double(imread(QQ??í?20110517210405.bmp));Mw=size(watermarked_image,1);Nw=size(watermarked_image,2);c=Mw/8;d=Nw/8;m=c*d; orig_watermark=double(imread(shan.PNG)); Mo=size(orig_watermark,1);No=size(orig_watermark,2); n=Mo*No; rand(state,7);pn_sequence_zero=round(rand(1,sum(sum(midba