title: Python : RuntimeWarning: overflow encountered
body: <p>When i run pyOpenTld i get RuntimeWarning: overflow encountered in int_scalars
  from this module. Why is this happening? </p>
  
  <pre><code>Warning (from warnings module):
      File "D:\Python27\lib\pyOpenTLD\TLD\IntegralImage.py", line 34
          op[cols * j + i] = A + B - C + value
  RuntimeWarning: overflow encountered in int_scalars
  </code></pre>
  
  <p>Thanks! ras</p>