title: Access multiple channels in OpenCV Mat
body: <p>What is the Syntax to access ith row of channel::n of a multi channel matrix. I can access (i,j) element of channel::n but what is the syntax to use functions like row, rowRange, .....</p>
  
  <p>Sample Code:</p>
  
  <pre><code>Mat M(10, 3, CV_32SC3);
  cout &lt;&lt; M.at&lt;Vec3d&gt;(0,0)[1] &lt;&lt; endl;  // This works
  cout &lt;&lt; M.row(0)[1] &lt;&lt; endl;    // Syntax of this
  </code></pre>