title: tesseract ChoiceIterator confidence threshold
body: <p>I'm trying to use tesseract (3.03) ChoiceIterator to list possible alternatives of each character in a serial number. For some characters it seems to be working fine:</p>
  
  <pre><code>symbol 3, conf: 82.660316   
     - 3 conf: 82.660316
     - B conf: 74.598289
     - S conf: 74.530128
  </code></pre>
  
  <p>For other characters it's not working (ie. it doesn't return any alternatives):</p>
  
  <pre><code>symbol I, conf: 90.924942
  </code></pre>
  
  <p>Now, I find it hard to believe that "I" is not easy to be confused with "1" (actually in my case the character is "1" not "I"). I'm guessing that tesseract must be discarding alternatives on the basis of their low confidence (ie. confidence below some threshold?) but I'm unable to find any suitable option. </p>