title: Crop image's area with openCV (java)
body: <p>I have detected a area (rectangle) in my image with openCv and i have stored the 4 points of rectangle with their coordinates.</p>
  
  <p>I would to crop the original image in this area.</p>
  
  <p>I have:</p>
  
  <pre><code>Mat image_original; 
  Point p1,p2,p3,p4;
  Mat image_output;
  </code></pre>
  
  <p>How i do this? 
  Thanks!</p>