error in calculating distance

I have a image and have divided it into blocks

C = mat2cell(I,[128 128],[128 128])

my output is

C = 

      [128x128 uint8]    [128x128 uint8]
      [128x128 uint8]    [128x128 uint8]

i have taken first block

A1=I(1:128, 1:128);

i want to calculte distance of A1 with C1 ,i tried euclidean distance but i get error

Error in ==> EuD at 23
Distance= sqrt(d);

[Pat]

pleas help to find the distance

[Grzegorz Knor]

How do you calculate d?

[Image Analyst]

Is d the Pythagorean theorem between each pixel's intensity, like sqrt(A1 - C1)? Wouldn't that be zero? What is C1? Is that the first block? Well isn't that also A1? So the difference would be zero?

[Pat]

function Distance=EuD(A,B)

[row,col]=size(B);

% load histogram;

% A=A{1};

for i=1:row

for j=1:col

D(i,j)=(A(i,j)- B(i,j))^2;

end

end

% To find the sum of D

d=0;

for i=1:row

for j=1:col

d=(D(i,j)+d);

end

end

Distance= sqrt(d);

S the first ditsance is zero,but how to calculate tahe distance between others

[Image Analyst]

Well why wouldn't your (inefficient, non-vectorized) function work for any A and B you pass in? Why not use RMS Error or PSNR instead?

[Walter Roberson]

You do not show us the error message, and you do not show us what C1 is.

[Pat]

Error in ==> EuD at 23

Distance= sqrt(d);

C1=[128x128 uint8]

[Image Analyst]

That's not an official MATLAB error message - the text that shows up in red in the command window. We need the official error message. Please, please simply copy and paste your command window - DON'T paraphrase.

[Walter Roberson]

C1 might be that size and data type, but did define it as

C1 = C{1,1};

or as something else?