title: OpenCV Python and SIFT features
body: <p>I know there is a lot of questions about <strong>Python</strong> and <strong>OpenCV</strong> but I didn't find help on this special topic.</p>
  
  <p>I want to extract <strong>SIFT keypoints</strong> from an image in python OpenCV.</p>
  
  <p>I have recently installed OpenCV 2.3 and can access to SURF and MSER but not SIFT.
  I can't see anything related to SIFT in python modules (cv and cv2) (well I'm lying a bit: there are 2 constants: <code>cv2.SIFT_COMMON_PARAMS_AVERAGE_ANGLE</code> and <code>cv2.SIFT_COMMON_PARAMS_FIRST_ANGLE</code>).</p>
  
  <p>This puzzles me since a while.
  Is that related to the fact that some parts of OpenCV are in C and other in C++?
  Any idea?</p>
  
  <p>P.S.: I have also tried pyopencv (another python binding for OpenCV &lt;= 2.1) without success.</p>