%Name:		Chris?Shoemaker
%Course:	EER-280?-?Digital?Watermarking
%Project:?	CDMA?based?using?multiple?PN?sequences?embeded?into?whole?object
%???????????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_object1）;	%Height
Nc=size（cover_object2）;	%Width

%?read?in?the?message?image?and?reshape?it?into?a?vector
file_name=‘_copyright_small.bmp‘;
message=double（imread（file_name））;
Mm=size（message1）;	????????????????????????%Height
Nm=size（message2）;	????????????????????????%Width
message_vector=round（reshape（messageMm*Nm1）./256）;

%?read?in?key?for?PN?generator
file_name=‘_key.bmp‘;
key=double（imread（file_name））./256;

%?reset?MATLAB‘s?PN?generator?to?state?“key“
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（McNc）-0.5））;
????
????if?message（kk）?==?0
????????watermarked_image=watermarked_image+k*pn_sequence;
????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_objectwatermarked_image_uint8McNc）

%?display?watermarked?Image
figure（1）
imshow（watermarked_image_uint8[]）
title（‘Watermarked?Image‘）