title: OpenCV - cvtColor does not change colorspace, it changes colors
body: <p>I am trying to make an object tracker using OpenCV 3.1.0 and C++ following this Python example: <a href="http://docs.opencv.org/3.1.0/df/d9d/tutorial_py_colorspaces.html#gsc.tab=0" rel="nofollow noreferrer">http://docs.opencv.org/3.1.0/df/d9d/tutorial_py_colorspaces.html#gsc.tab=0</a>.</p>
  
  <p>I have some problems with cvtColor() function, because it changes the colors of my images and not its colorspace. I have this code:</p>
  
  <pre><code>Mat original_image;
  original_image = imread(argv[1], CV_LOAD_IMAGE_COLOR); // The image is passed as arg
  if (!original_image.data)
  {
      printf("Problem!\n");
      return -1;
  }
  
  // From BGR to HSV
  Mat hsv_image(original_image.rows, original_image.cols, original_image.type());
  cvtColor(original_image, hsv_image, CV_BGR2HSV);
  imwrite("hsv_image.png", hsv_image);
  </code></pre>
  
  <p>original_image is a CV_8UC3, compatible with cvtColor() and should be originally in BGR colorspace.</p>
  
  <p>I made the test image below with GIMP:</p>
  
  <p><a href="https://i.stack.imgur.com/8CzKb.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/8CzKb.png" alt="Test image"></a></p>
  
  <p>And I get this image as result:</p>
  
  <p><a href="https://i.stack.imgur.com/bks8V.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/bks8V.png" alt="HSV image - result"></a></p>
  
  <p>I decided to try the conversion from BGR to RGB, changing BGR2HSV to BGR2RGB, and with the same test image, I get this result</p>
  
  <p><a href="https://i.stack.imgur.com/Izsqq.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/Izsqq.png" alt="RGB image - result"></a></p>
  
  <p>Here, it's more clear that the channels of the image are changed directly...</p>
  
  <p>Has anybody any idea about what's happening here?</p>