title: Opencv compare Rects
body: <p>I get a vector of Rect by calling DetectMultiScale:</p>
  
  <pre><code>face_cascade.detectMultiScale(ImgGray,faces,1.1,2,0|CV_HAAR_SCALE_IMAGE);
  </code></pre>
  
  <p>But Compare requires Mat:</p>
  
  <pre><code>compare(OriginalImg,roi,dist,CMP_EQ);
  </code></pre>
  
  <p>How do I convert Rect to Mat to make the comparison or is there a way to compare Rects?</p>