title: Convert gray pixel_array from DICOM to RGB image
body: <p>I'm reading DICOM gray image file as</p>
  
  <p><code>gray = dicom.dcmread(file).pixel_array</code></p>
  
  <p>There I've got (x,y) shape but I need RGB (x,y,3) shape</p>
  
  <p>I'm trying to convert using CV</p>
  
  <p><code>img = cv2.cvtColor(gray, cv2.COLOR_GRAY2RGB)</code></p>
  
  <p>And for testing I'm writing it to file <code>cv2.imwrite('dcm.png', img)</code></p>
  
  <p>I've got extremely dark image on output which is wrong, what is correct way to convert pydicom image to RGB?</p>