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dwt_embed.m：源码内容

							%Name:		Chris Shoemaker
%Course:	EER-280 - Digital Watermarking
%Project: 	Embeding of CDMA watermark into H1,V1,D1 componants of a 1-scale DWT
%           Watermark Embeding
clear all;
% save start time
start_time=cputime;
k=2;            % set the gain factor for embeding
% read in the cover object
file_name='_lena_std_bw.bmp';
cover_object=double(imread(file_name));
% determine size of watermarked image
Mc=size(cover_object,1);	%Height
Nc=size(cover_object,2);	%Width
% read in the message image and reshape it into a vector
file_name='_copyright.bmp';
message=double(imread(file_name));
Mm=size(message,1);	                        %Height
Nm=size(message,2);	                        %Width
message_vector=fix(reshape(message,Mm*Nm,1)./2);
% read in key for PN generator
%file_name='_key.bmp';
%key=double(imread(file_name))./2;%256
% reset MATLAB's PN generator to state "key"
rand('state',16);
%三层harr小波变换
[cA1,cH1,cV1,cD1] = dwt2(cover_object,'haar');
[cA2,cH2,cV2,cD2] = dwt2(cA1,'haar');
[cA3,cH3,cV3,cD3] = dwt2(cA2,'haar');
[r1,c1] = size(cA3);
pn_sequence_h1=round(2*(rand(r1,c1)-0.5));
cA3=cA3+20*pn_sequence_h1;
% add pn sequences to H1 and V1 componants when message = 0 
 pn_sequence_h=round(2*(rand(Mc/2,Nc/2)-0.5));
 pn_sequence_v=round(2*(rand(Mc/2,Nc/2)-0.5));
for (kk=1:length(message_vector))  
    
    if (message(kk) == 0)
        cH1=cH1+k*pn_sequence_h;
        cV1=cV1+k*pn_sequence_v;
    end
end
% perform IDWT
cA2 = idwt2(cA3,cH3,cV3,cD3,'haar',[Mc/4,Nc/4]);
cA1 = idwt2(cA2,cH2,cV2,cD2,'haar',[Mc/2,Nc/2]);
watermarked_image = idwt2(cA1,cH1,cV1,cD1,'haar',[Mc,Nc]); 
% convert back to uint8
watermarked_image_uint8=uint8(watermarked_image);
% write watermarked Image to file
imwrite(watermarked_image_uint8,'dwt_watermarked.bmp','bmp');
% display processing time
elapsed_time=cputime-start_time,
% calculate the PSNR
psnr=psnr(cover_object,watermarked_image_uint8,Mc,Nc),
% display watermarked image
figure(1)
imshow(watermarked_image_uint8,[])
title('Watermarked Image')
figure(2)
subplot(2,2,1);
imshow(cA1,[]);
subplot(2,2,2);imshow(cA2,[]);
subplot(2,2,3);imshow(cA3,[]);
subplot(2,2,4);imshow(cD1,[]);
figure(3)
imshow(cA3,[]);

						