Matrix manipulation

Hi I'm new to Matlab and seem to be struggling again. I'm trying to subtract corresponding elements from two image matrices i.e.

matrix 1= A B matrix 2= a b C D c d

I'm trying to get (A-a)^2+(B-b)^2.....

Thanks in advance for any help, it;s really appreciated.

Answer 1

[the cyclist]

Not 100% if this is what you mean, but ...

M1 = [1 2 3 4];

M2 = [5 6 7 8];

M3 = (M1-M2).^2;

[Karen Rafferty]

Yeah that seems like it. I'm trying to do it for two 568 by 752 matrices. From the above I'd be doing M3=(1-5)^2 + (2-6)^2 + (3-7)^2+ (4-8)^2

Is it possible to do so? I'm guessing I'd need a for loop.

Thanks

[Matt Fig]

No FOR loop is needed.

M3 = sum((M1-M2).^2)

If you expect a scalar from the operation, do this:

M3 = sum((M1(:)-M2(:)).^2)

[Karen Rafferty]

I tried this: M3 = sum((Groundtruth-Haarbk2).^2)

but got the error message:

??? Error using ==> minus

Class of operand is not supported.

[Matt Fig]

Yes, what version are you using, because this works find on my system.

Try this:

sum((Groundtruth-double(Haarbk2)).^2)

[Karen Rafferty]

Thanks that seems to be working now

Answer 2

[Sean de Wolski]

M3 = sum((Groundtruth(:)-double(Haarbk2(:))).^2);

Answer 3

[Karen Rafferty]

I've tried to implement these by: for i = 1:M for j = 1:N Ans= sum(abs(Groundtruth(i,:)-Haarbk2(i,:))).^2; end end

But I keep getting the error message:

??? Error using ==> minus Class of operand is not supported.

[Matt Fig]

So what does this return:

class(Groundtruth)

class(Haarbk2)

[Karen Rafferty]

They give:

>> class(Groundtruth)

ans =double

>> class(Haarbk2)

ans =uint8

Should they be the same?

[Sean de Wolski]

Yes. You can't have a negative unsigned integer.

Haarbk2 = double(Haarbk2);

Answer 4

[Karen Rafferty]

Thank you soo much for all your help, I think I've it sorted now :D