title: Using hierarchy in findContours () in OpenCV?
body: <p>When finding contours, I used the CV_RETR_CCOMP argument. This is supposed to create a two level hierarchy - the the first level are for outer contours, the second level are for boundaries of the holes. However, I have never used a hierarchy before so I am not familiar with this.</p>
  
  <p>Could someone instruct my on how to access the boundaries of the holes only? I want to disregard the outer contours and only draw the hole boundaries. Code examples will be appreciated. I am using the C++ interface not the C, so please don't suggest C functions (i.e. use findContours () instead of cvFindContours ()).</p>