title: Convert single channle image to 3 channel image C++ / OpenCV
body: <p>Im using openCV C++</p>
  
  <p>Im need to convert a single channel image to 3 channels image. So i can use this: <code>cvCvtColor(result,gray,CV_BGR2GRAY);</code></p>
  
  <p>I cannot do that because the result img is a single channel image. Any ideas?</p>