cdma.rar_CDMA dct_CDMA watermarking_Image watermarking

%Name: Chris Shoemaker %Course: EER-280 - Digital Watermarking %Project: CDMA based using multiple PN sequences embeded into whole object % Watermark Embeding % 图像未作变化，在空间域上直接修改像素值。每出现一个黑色像素就把整个图像素值加一个PN矩阵，改动较大，提取水印效果不理想 % 只能处理灰度图，因为彩图为三维数据，可以嵌入相应三维PN矩阵，但提取时无法比较两个三维矩阵的相关值 clear all; % save start time start_time=cputime; k=2; % set the gain factor for embeding水印强度 % read in the cover object file_name='lena.bmp'; %cover_object=double(imread(file_name));%产生三维的随机矩阵修改原图像素值，但是提取水印时无法比较两个三维矩阵的相关系数，因此无法得到彩图 cover_object=double(rgb2gray(imread(file_name)));%处理灰度图,产生的随机矩阵是二维的 % 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='56.bmp'; message=double(imread(file_name)); Mm=size(message,1); %Height Nm=size(message,2); %Width message_vector=round(reshape(message,Mm*Nm,1)./256);%归一取整变二值图 % read in key for PN generator %file_name='PN_key.bmp'; %key=double(imread(file_name))./256; key=30; % reset MATLAB's PN generator to state "key" %rand('state',key(1:35,1)); rand('state',key); watermarked_image=cover_object; % when message contains a '0', add pn sequence with gain k to cover image for kk=1:length(message_vector) %pn_sequence=round(2*(rand(Mc,Nc,3)-0.5));%对整个原图像素点加PN随机数，随机矩阵与原图大小一致 pn_sequence=round(2*(rand(Mc,Nc)-0.5));%若是灰度图，产生二维随机矩阵，无法计算两个三维矩阵的相关值 if message(kk) == 0 watermarked_image=watermarked_image+k*pn_sequence;%有多少个黑色像素点就加几次随机矩阵 end end % convert back to uint8 watermarked_image_uint8=uint8(watermarked_image); % write watermarked Image to file imwrite(watermarked_image_uint8,'cdma_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')