Assigning random values to image pixels

I am trying to assign random values to the elements of a rectangular region within an image matrix, so that the result looks something like this:

This is my approach:

I = zeros(128,128);
for i=32:96
    for j=32:96
        I(i,j) = rand();
    end
end
imshow(I);

Is there a more efficient way of doing this, perhaps without a double for-loop?

Any suggestions would be greatly appreciated.

Answer 1

[Guillaume]

I = zeros(128, 128)
I(32:96, 32:96) = rand(96-32+1, 96-32+1);