title: how to pass opencv mat by reference
body: <p>i have  1 matrix (3channel)     ->      cv::Mat channels[3]; </p>
  
  <p>&amp; 3 matrix (1channel)      ->     cpu_filter0,cpu_filter90,cpu_filter120 </p>
  
  <p>previously I did something like this,</p>
  
  <pre><code>cv::Mat cpu_filter0,cpu_filter90,cpu_filter120
  cv::Mat channels[] = {cpu_filter0,cpu_filter90,cpu_filter120}
  </code></pre>
  
  <p>but now I want to do like this </p>
  
  <pre><code>cv::Mat cpu_filter0,cpu_filter90,cpu_filter120
  cv::Mat channels3[3];
  channels[0] = &amp;cpu_filter0, channels[1] = &amp;cpu_filter90, channels[0] = &amp;cpu_filter120;
  </code></pre>
  
  <p>or by,</p>
  
  <pre><code>cv::Mat channels3[] = {&amp;cpu_filter0_0,&amp;cpu_filter120_120,&amp;cpu_filter240_240};
  </code></pre>
  
  <p>want to know what is the right way to do this??</p>