title: matlab imdilate structural element origin confusion
body: <p>Consider the following operation:</p>
  
  <pre><code> a =
  
       0     0     0     0
       0     1     0     0
       0     0     1     0
       0     0     0     0
  
   b=imdilate(a,[1,1;1,1])
  
  b =
  
       0     0     0     0
       0     1     1     0
       0     1     1     1
       0     0     1     1
  </code></pre>
  
  <p>The above result indicates the origin of the structual element is [2,2]. If the origin is floor((size([1,1;1,1])+1)/2)=[1,1] by the definition (<a href="http://www-rohan.sdsu.edu/doc/matlab/toolbox/images/morph4.html" rel="nofollow">http://www-rohan.sdsu.edu/doc/matlab/toolbox/images/morph4.html</a>)</p>
  
  <pre><code>b=
      1     1     0     0
      1     1     1     0
      0     1     1     0
      0     0     0     0
  </code></pre>
  
  <p>What's wrong with my understanding? Thank you!</p>