title: cv2.imshow command doesn't work properly in opencv-python
body: <p>I'm using opencv 2.4.2, python 2.7
  The following simple code created a window of the correct name, but its content is just blank and doesn't show the image:</p>
  
  <pre><code>import cv2
  img=cv2.imread('C:/Python27/03323_HD.jpg')
  cv2.imshow('ImageWindow',img)
  </code></pre>
  
  <p>does anyone knows about this issue?</p>