how can i minimize this loop timing please suggest.....

window=100;
wi=(window-1)/2;
temp2=0;
for k=0:row-window
  for l=0:col-window

        for i=1:window
            for j=1:window
                temp1(i,j)=double(l1(i+k,j+l));       

            end
        end
        LocalMean=mean(mean(temp1));
        %         LocalVar=var(var(temp1));

        for i=1:window
            for j=1:window
                temp2=temp2+(temp1(i,j)-LocalMean)^2;
            end
        end

        temp3(k+wi,l+wi)=temp2/(101^2); 
        temp2=0;
    end
  end

[EDITED, Jan, code formatted]

Answer 1

[Jan]

window = 100;
wi = ceil((window-1)/2);  % CEIL is required!
c1 = 101 ^ 2;
temp3 = zeros(row - window + wi);  % Pre-allocate!!!
for k = 0:row-window
  for l = 0:col-window
     temp1     = double(l1(1+k:window+k, 1+l:window+l);
     LocalMean = sum(temp1(:)) / numel(temp1);
     kk        = temp1(:) - LocalMean;
     temp3(k+wi,l+wi) = (kk' * kk) / c; 
  end
end

wi = (window-1)/2 is not an integer for window = 100. You need CEIL,m FLOOR or ROUND.