title: Decrease image resolution in OpenCV
body: <p>I'm using OpenCV to capture images from A4Tech camera. When I try to decrease image resolution, image assertion fails:</p>
  
  <pre><code>CvCapture *camera = cvCreateCameraCapture(1); // 0 is index of Laptop integrated camera
  cvSetCaptureProperty( camera, CV_CAP_PROP_FRAME_WIDTH, 160 );
  cvSetCaptureProperty( camera, CV_CAP_PROP_FRAME_HEIGHT, 140 );
  assert(camera); // This is passed
  while(true)
  {
      // ....
      IplImage * image=cvQueryFrame(camera);
      assert(image); // This fails. (Line 71 is here)
      // ....
  }
  </code></pre>
  
  <p>Output is:</p>
  
  <pre><code>HIGHGUI ERROR: V4L: Initial Capture Error: Unable to load initial memory buffers.
  udpits: main.cpp:71: int main(int, char**): Assertion `image' failed.
  Aborted
  </code></pre>