Help in DCT watermark embedding process

2013 2 23
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hi everyone, i got confuse regarding of this approach of watermark and still now i can't get it clearly therefor i make a post hopeful someone help me the required : 1- the steps of embedding process 2- Matlab script
Many Thanks

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Walter Roberson
Walter Roberson 2013-2-23

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Yasir
Yasir 2013-2-23
编辑：Yasir 2013-2-23
many Thanks for reply Sir this link it;s diffrent what i have been read about of DCT could you open this link http://ebookbrowse.com/lecture7-dct-domain-watermarking-pdf-d287695195 and there is block diagram for embedding process could you help me to script it in matlab
Walter Roberson
Walter Roberson 2013-2-23
I would prefer you spent your time searching this resource as there have been a fair number of postings on using DCT and watermarking.
Once you have gone through those, you can start coding yourself, and post here when you encounter errors that you do not understand and cannot solve with the debugger.
I have a book to read, groceries to buy...
Yasir
Yasir 2013-2-23
i already did ,but i failed i know how to make dct for image and block it but i don;t know how to embed original image with watermark image also how to make a pseudo roundom for watermark image
i appreciated your help friend ,
Walter Roberson
Walter Roberson 2013-2-23
Read Image Analyst's watermarking demo.
Yasir
Yasir 2013-2-26
编辑：Yasir 2013-2-26
hi Walter,plz your help to finilize it Kindly i tried the below code to implement it but seems no thing am working in Cox DCT approach depend to forumla ti=ti+atixi, a=0.1
[fname pthname]=uigetfile('*.jpg;*.png;*.tif;*bmp','Select the Asset Image'); %select image
I=imread([pthname fname]);
origy=rgb2gray(I);
origdct=dct2(origy);
[rows cols]=size(origdct);
imglen=rows*cols;
origrddct=reshape(origdct, 1, imglen);
origs=sort(origrddct,'descend');%re-ordering all the absolute values
wmsz=2223; %watermark size
W=randn(1,wmsz);%generate a Gaussian spread spectrum noise
%find the index of largest coffiencent
for k=1:wmsz
for i=1:imglen
if (origs(k)==origrddct(i))
m(k)=i;
display(i);
end
end
end
%embedded formula
for j=1 :wmsz
origsn(j)=((origs(j) * 1)+ (0.3*origs(j)* W(j)));
end
for n=1: wmsz-1
for f=1:imglen
if (f == m(n) )
origrddct(f)=origsn(n);
end
end
end
mx=reshape(origrddct,rows,cols);
oridctx=idct2(mx);
figure , imshow(oridctx);
figure,imshow(origy);

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Yasir
Yasir
2013-2-23

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