Image encoding matlab code

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marie lasz
marie lasz 2020-12-6
评论： Rik 2020-12-7
hello
this code is working perfectly but it is embedding secret message in upper left square only. but I want to embedd on every block i.e i have 64x64 blocks , in each bloock there are 8x8 blocks. I am a bit confused but would be grateful for any help because i am a beginner level of matlab.
mark=imbinarize(Watermark_Image);
marksize=size(mark);
rm=marksize(1); %rowMat is the number of lines of the watermark image
cm=marksize(2);
figure(1);subplot(2,3,2);imshow(Watermark_Image),title('Watermark image');
T = dctmtx(8);
alpha=105; %The scale factor, which controls the strength of the watermark addition, determines how much the frequency domain coefficients are modified
k1=randn(1,8); %Generate two different random sequences, ruturns nxm matrix of normally distributed random numbers
k2=randn(1,8);
Dct_Image=blkproc(Y,[8 8],'dct2');
Output_Image=Dct_Image;
for E=1:4096
for i=1:rm
for j=1:cm
x=(i-1)*8;
y=(j-1)*8;
if mark(i,j)==1
k=k1;
else
k=k2;
end
% Output_Image(x,y)=Dct_Image(x,y)+alpha*k;
Output_Image(x+1,y+8)=Dct_Image(x+1,y+8)+alpha*k(1);
Output_Image(x+2,y+7)=Dct_Image(x+2,y+7)+alpha*k(2);
Output_Image(x+3,y+6)=Dct_Image(x+3,y+6)+alpha*k(3);
Output_Image(x+4,y+5)=Dct_Image(x+4,y+5)+alpha*k(4);
Output_Image(x+5,y+4)=Dct_Image(x+5,y+4)+alpha*k(5);
Output_Image(x+6,y+3)=Dct_Image(x+6,y+3)+alpha*k(6);
Output_Image(x+7,y+2)=Dct_Image(x+7,y+2)+alpha*k(7);
Output_Image(x+8,y+1)=Dct_Image(x+8,y+1)+alpha*k(8);
end
end
end
% firsttX = blkproc(after,[8,8], 'P1*x', mask);
resultY=uint8(blkproc(Output_Image,[8 8], 'idct2'));
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marie lasz
marie lasz 2020-12-6
@kalyan you can take any image of 32x32 for watermark and 512x512 for hoat image.
Rik
Rik 2020-12-7
I restored the original post from Google cache. @Marie, don't remove crucial parts of your question.

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Image Analyst
Image Analyst 2020-12-6
The easy way is to just resize your image to one 64x64 thumbnail, and then replicate it to make a tiled image the same size as your cover image. You might use repmat(), imtile(), or montage(). Or see my attached demo.
I put the watermark into bitplane 6 so you can see it replicated a little bit in the middle image of the right column. Adapt as needed.
  2 个评论
Image Analyst
Image Analyst 2020-12-6
Marie, not sure what your edit was. But did this work for you?
marie lasz
marie lasz 2020-12-7
Good Morning,
I didn't try that because it is changing the whole criteria. I will try that later but now trying to fix this as per requirement.

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