Demosaicing Produces Grayscale Result

C++
,
1

I’m attempting to produce a demosaiced RGB image from a RAW8 UVC stream. The RAW8 data is stored on the G channel of the incoming VideoCapture. I’ve tried many different permutations, but the result of OpenCV’s demosaicing algorithm always generates a grayscale image.

#include <iostream>
#include <opencv2\opencv.hpp>

using namespace cv;
using namespace std;

int main()
{
  namedWindow("Debayer Test");

  Mat image;
  Mat channels[3];
  VideoCapture cap(0);

  if (!cap.isOpened())
  {
    cout << "cannot open camera";
  }

  while (true)
  {
    cap >> image;
    split(image, channels);

    Mat output(image.size(), image.type());
    demosaicing(channels[1], output, COLOR_BayerBG2BGR);

    imshow("Demosaic Result", output);

    waitKey(25);
  }
  return 0;
}

Any suggestions? Even if I’ve selected the wrong Bayer pattern, I’d expect the result of ‘demosicing’ to be full-color (albeit incorrectly mapped).