title: How correlation help in matching two images?
body: <p>It is known that if we are finding the most matching window to the current window in the entire image, then wherever the correlation is maximised then that is the matching window. </p>
  
  <pre><code> [22 12 14] (window)
  
    (image)   
   [22 12 34   54 ]
   [112 34 54 111 ]
   [12 22 12   34 ]
   [11 22 12   14 ]
  </code></pre>
  
  <p>But correlation is product of corresponding values in two windows.
  So, if some of the window have high intensity values then they will always provide better match. e.g. in above example we will have higher correlation value for 2nd row.</p>