What are color conversion codes ending in FULL for?

Question

Several color conversion codes in OpenCV 3.2 have two versions, one ending in _FULL, and one not, e.g.:

  cv::COLOR_BGR2HSV_FULL = 66,
  cv::COLOR_RGB2HSV_FULL = 67,
  cv::COLOR_BGR2HLS_FULL = 68,
  cv::COLOR_RGB2HLS_FULL = 69,
  cv::COLOR_HSV2BGR_FULL = 70,
  cv::COLOR_HSV2RGB_FULL = 71,
  cv::COLOR_HLS2BGR_FULL = 72,
  cv::COLOR_HLS2RGB_FULL = 73, 

What is the difference between the two? I couldn't find it in the documentation. Specifically, when I use a color conversion code like in:

converted_img = cv2.cvtColor(img, cv2.COLOR_BGR2HLS)

Thanks!

Answer 1

The hue range in Open CV is [0,179], the saturation and intensity range from [0,255], as per Official Docs. So one has to normalise the hue to the range [0,255]. The options with "_FULL" have the hue range defined to [0-255].