title: How to convert a 1 channel image into a 3 channel with opencv2?
body: <p>I'm really stumped on this one. I have an image that was <em>[BGR2GRAY]'d</em> earlier in my code, and now I need to add colored circles and such to it. Of course this can't be done in a 1 channel matrix, and I can't seem to turn the damned thing back into 3.</p>
  <p><code>numpy.dstack()</code> crashes everything</p>
  <p>GRAY2BGR does not exist in opencv2</p>
  <p><code>cv.merge(src1, src2, src3, dst)</code> has been turned into <code>cv2.merge(mv)</code> where mv = &quot;a vector of matrices&quot;, whatever that means.</p>
  <p>Any ideas?</p>
  <p><a href="https://www.google.com/url?sa=t&amp;rct=j&amp;q=&amp;esrc=s&amp;source=web&amp;cd=2&amp;ved=0CDcQFjAB&amp;url=http%3A%2F%2Ffossies.org%2Funix%2Fmisc%2FOpenCV-2.4.3.tar.gz%3Aa%2FOpenCV-2.4.3%2Fdoc%2Fopencv2refman.pdf&amp;ei=awUWUfnbJ4Ly0wGmuoC4Cw&amp;usg=AFQjCNHZZKb8aioAVevF3gpQQeuRT7SxyQhttps://www.google.com/url?sa=t&amp;rct=j&amp;q=&amp;esrc=s&amp;source=web&amp;cd=2&amp;ved=0CDcQFjAB&amp;url=http%3A%2F%2Ffossies.org%2Funix%2Fmisc%2FOpenCV-2.4.3.tar.gz%3Aa%2FOpenCV-2.4.3%2Fdoc%2Fopencv2refman.pdf&amp;ei=awUWUfnbJ4Ly0wGmuoC4Cw&amp;usg=AFQjCNHZZKb8aioAVevF3gpQQeuRT7SxyQ" rel="noreferrer">Opencv2.4.3 refmanual</a></p>