title: Crop Mat image in OpenCV 2.4.3 (iOS)
body: <p>I am trying to crop images coming out of the video stream with OpenCV for iOS.  I am not trying to do anything fancy, simply crop the image, and display it.  I have tried <a href="https://stackoverflow.com/questions/7041181/equivalent-to-cvsetimageroi-in-the-opencv-c-interface">this</a>, and <a href="https://stackoverflow.com/questions/8267191/how-to-crop-a-cvmat-in-opencv">this</a>, neither seem to work for me.  As a delegate method, I get the current cv::Mat image passed in, so all I need is the code that will create the crop effect.  </p>
  
  <p>I could do something as complicated as <a href="https://stackoverflow.com/questions/13098073/adjust-corners-and-crop-the-image-opencv">this</a> if need be, but I only need a rectangular crop, so I think there is an easier way.  I just dont understand why setting the ROI is not working for me!</p>
  
  <pre><code>cv::Rect myROI(10, 10, 100, 100);
  cv::Mat croppedImage = src(myROI);
  
  src.copyTo(croppedImage);
  
  
  [displayView setImage:[UIImage imageWithCVMat:src]];
  </code></pre>
  
  <p>^^^not working, just displaying original image</p>