title: How to make tesseract to recognize only numbers, when they are mixed with letters?
body: <p>I want to use <code>tesseract</code> to recognize only numbers. The problem is that I have mixture of numbers &amp; letters and when I use <code>SetVariable("tessedit_char_whitelist", "0123456789")</code><br>
  for every symbol tesseract returns wrong digit.</p>
  
  <p>Can I set a threshold value so that <code>tesseract</code> omits the symbols with low resemblance?  </p>
  
  <p>NOTE: I set <code>tesseract</code> to recognize only digits so there is no confusion between O and 0.</p>