title: Why is the Python build of OpenCV (cv2.pyd) so small?
body: <p>I wanted to use OpenCV with Python, so I downloaded OpenCV for Windows and got a folder of ~3.7GB after decompression. What surprised me was that the only file I needed was cv2.pyd, which was so small (~11MB) comparing to the C builds (~674MB). I simply copied it to my Python lib-packages folder without adding anything to my PATH and it worked perfectly.</p>
  
  <p>I don't know how Python binding works, and I thought it should call C/C++ implementations under the hood. However, cv2 did not seem to require any C/C++ library. It just looks like magic to me.</p>