title: How to divide an image into blocks in MATLAB?
body: <p>I have a 256x256 image and I want to divide it into 4 blocks of 128x128 each and address them as A1 to A4. Now I want to call them separately and do some operations on them. I know this can be done using the <code>blkproc</code> function -- but how exactly?</p>
  
  <p>Do I call <code>blkproc</code> like this?</p>
  
  <pre><code>B=blkproc(I,[4 4],?)
  </code></pre>
  
  <p>What do I put in place of the "?", and how can I address the 4 blocks created?</p>