title: Set src and dst img the same for opencv resize function
body: <p>I am trying to resize an <code>cv::Mat img</code> with OpenCV. When I am using function <code>cv::resize()</code>, I set <code>src</code> and <code>dst</code> img to be the same as input img like <code>cv::resize(img, img)</code>. And when I test the program, so far it works correctly. But I am a bit confused how the resize function is implemented cause when I read the documentation it said we need to pre-allocate the <code>dst</code> img before resizing.</p>
  
  <p>Can anyone explain it to me?
  Thanks.</p>