title: Compilation error when not using template [opencv]
body: <p>I have this part of code    </p>
  
  <pre><code>static void translateMod(cv::Mat&amp; imgIn, cv::Mat&amp; imgOut, int nb_pixels) {
          int w = imgIn.cols, h = imgIn.rows;
          if (nb_pixels &gt;= w) nb_pixels = w;
          cv::Rect left(0, 0, w - nb_pixels, h);
          cv::Mat ROI = imgIn(left);
          cv::imshow("ROI", ROI);
      }
  </code></pre>
  
  <p>The problem is that when I compile this, I have error mentionning that <code>"imshow is not a member of 'cv'"</code>, but when I add a template like this</p>
  
  <pre><code>template &lt;typename T&gt;
      static void translateMod(cv::Mat&amp; imgIn, cv::Mat&amp; imgOut, int nb_pixels) {
              int w = imgIn.cols, h = imgIn.rows;
              if (nb_pixels &gt;= w) nb_pixels = w;
              cv::Rect left(0, 0, w - nb_pixels, h);
              cv::Mat ROI = imgIn(left);
              cv::imshow("ROI", ROI);
          }
  </code></pre>
  
  <p>it works and I can compile and even execute.</p>
  
  <p>Do someone know what happens here? :/</p>
  
  <p>Thanks for all</p>