title: Opencv: image, retrieved from camera capture is always gray
body: <p>I am always getting a grey screen when showing image using opencv, the image is captured from camera. </p>
  
  <pre><code>capture = cvCaptureFromCAM(-1);
  cvGrabFrame(capture);
  image = cvRetrieveFrame(capture);
  cvShowImage("name", image);
  </code></pre>
  
  <p>after  this I see the grey screen, even if I do in cycle. But the same code works well on another computer. What is the problem? The same opencv library version is used on both computers. Working in the Visual Studio 2010, C++
  Opencv version 2.2.0</p>
  
  <p>EDIT 1: The camera used in both computers is the same.
  And I have tried to rebuild the opencv on the computer where the problem happens, it didn't help. </p>