title: OpenCV draw non-matching points
body: <p>I have followed <a href="http://docs.opencv.org/3.0-beta/doc/py_tutorials/py_feature2d/py_table_of_contents_feature2d/py_table_of_contents_feature2d.html" rel="nofollow noreferrer">OpenCV Feature Detection and Description tutorial</a> and used SIFT and other algorithms in OpenCV to find matching feature points between 2 images. From what i understood, these algorithms can find the similar regions between 2 images. But i am interested in identifying the different or dis-similar regions.<br><br> How can i draw all the NON-MATCHING feature points on both the images? Further more, can i draw boundaries around these non-matching points to be able to show which regions in the 2 images are different?</p>
  
  <p>I am using Python code on Windows 7 and build from latest OpenCV source.</p>