i had converted image into blocks. I converted blocks to linear array. Next i calculated mean values for first 8 arrays as given below. now i want to calculate error values by using the formula: sum(linear array(:,1)​-mean(:,1)​).^2. please send code.

for i=1:4:nr-3

    for j=1:4:nc-3

      block=I(i:i+3,j:j+3);

      %convert 4X4 into 16X1 column vector
      tv(:,col)=reshape(block,16,1);

      col=col+1;
      count=count+1;
      column=column+4;

    end

   row=row+4;

end

%find mean of 8 arrays me=1; nn=8; nnn=1; for count=1:nr+nc cv(:,r) = mean(tv(:,me:nn*nnn), 2); r=r+1; nnn=nnn+1; me=me+8; end

[Image Analyst]

Try this http://www.mathworks.com/matlabcentral/answers/13205-tutorial-how-to-format-your-question-with-markup