title: Extract selected region from image with OpenCV
body: <p>I have a region of an image selected, like this: </p>
  
  <p><a href="http://slideplayer.com/4593320/15/images/9/Intelligent+scissors+http%3A%2F%2Frivit.cs.byu.edu%2FEric%2FEric.html.jpg" rel="nofollow noreferrer">http://slideplayer.com/4593320/15/images/9/Intelligent+scissors+http%3A%2F%2Frivit.cs.byu.edu%2FEric%2FEric.html.jpg</a></p>
  
  <p>and now, using OpenCV I would like to extract the region selected.</p>
  
  <p>How could I do it? I have already researched but nothing useful got.</p>
  
  <p>Thanks in advance.</p>