title: In matlab, how to convert a list of points to a binary matrix
body: <p>How would a list of points be converted to a binary matrix? Hopefully the operation will perform  suitably for 640x640 images. Here is an example:</p>
  
  <pre><code>% the points
  p = [2 2;2 3;3 3]
  
  % the images is 4x4
  img=zeros(4,4)
  
  % set img to 1 for all points in p
  </code></pre>
  
  <p>??? this is the question?</p>
  
  <p>% resulting binary image
  img =</p>
  
  <pre><code> 0     0     0     0
   0     1     0     0
   0     1     1     0
   0     0     0     0
  </code></pre>