how can we find distance between two image blocks?

i've divided the image into overlapping blocks.... i've calculated the correlation of these blocks with each other..

now i want two calculate the distance between these blocks like

distance between block 2 ans block 3.

 block2=[24 42;107 110];
 block3=[25 24; 55 56];

i've used the formula as:

    distance=norm(block2-block3);

i got the following error

 Undefined function 'norm' for input arguments of type 'uint8'.

how this type of error can be eliminated?

plz help me

Answer 1

[Image Analyst]

Cast both to double first. You need to do that anyway, because uint8 does not allow negative numbers, while a subtraction requires it.

Answer 2

[HABTE TADESSE LIKASSA]

norm_two = 8*norm(Y, 2) 
Undefined function 'norm' for input arguments of type 'uint8'

How can I solve this please?

[Image Analyst]

Review my answer above.

Cast Y to double first.