how to add a matrix with the pixel of an image

Hi I want to add a matrix with the pixels of an image.image size is 512 512 and matrix size is 2*2.

I=imread('lina512.bmp');
key=[8 5;5 3];
k=de2bi(key);
red=I(:,:,1);
I1=de2bi(red(:));

I dont know how to do bitwise xor

[Walter Roberson]

What size of results are you expecting?

What does bitwise xor have to do with adding?

[sadiqa ilyas]

size of the output would be of size of the original image.

[Guillaume]

As Walter also asked:

What does bitwise xor have to do with adding?

One thing for sure, there's no need for slow and unnecessary de2bi conversion in order to perform bitwise xor. But if what you want to do is bitwise xor instead of an addition (two completely different things) then it's not clear what should be xor'ed with what.

[sadiqa ilyas]

k(binary )of key matrix is xored with the binary of the pixels.

I=imread('lina512.bmp');
key=[8 5;5 3];
k=de2bi(key);
red=I(:,:,1);
I1=de2bi(red(:));

[x y]=size(I1);
zor=zeros(size(I1));
for i=1:x
            zor(i,:)=xor(I1(i),k)% gives error.
end
zor;
Can u plz tell what is the mistake

[Walter Roberson]

Your image is probably 8 bit so your I1 is probably something by 8. Your key values are at most 8 so only need 4 bits and there are 4 of them so k is 4x4. zor is the same size as I1 so it is something by 8. You have a for loop over the number of rows in I1 so I1(i) will be a scalar representing one bit (not a row of bits). Your xor that scalar with the 4x4 k so you get a 4x4 result. You try to store that 4x4 result in zor(i, :) which is 1x8.