I am playing one of the rosbag files which has an image topic /image_front_left of type `8UC3`. In my subscriber callback I am attempting to convert it to bgr8 format with: `img = self.bridge.imgmsg_to_cv2(msg,'bgr8')` I think this makes sense, but I get an error: `[8UC3] is not a color format. but [bgr8] is. The conversion does not make sense` Now I don't think this makes sense, as `8UC3` is a color format. Am I doing something wrong in subscribing this way? Do you have example code subscribing to the image topic?