Image encoding matlab code

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'));

[KALYAN ACHARJYA]

Please share the complete code with images (attach).

[Image Analyst]

How about if you resize your watermark image to match the size of the cover image before you encode it?

[marie lasz]

Yes i did that but for the info i put 32x32 watermark in 512x512 rgb image. That is the problem that it is saving whole image in one square but i want to embedd it using a eandom pisition of 64x64 blicks

[marie lasz]

@kalyan you can take any image of 32x32 for watermark and 512x512 for hoat image.

[Rik]

I restored the original post from Google cache. @Marie, don't remove crucial parts of your question.

Answer 1

[Image Analyst]

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.

[Image Analyst]

Marie, not sure what your edit was. But did this work for you?

[marie lasz]

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.