VideoCapture.read() giving different pixel values in Python and C++

C++
1

Hi everyone,
I am trying to read input from a camera and run Bayer conversion on windows. The camera is supposed to give 10 bit data. I found a working script in python, which I am trying to replicate in C++. But VideoCapture’s read function itself is giving different pixel values in python and C++. What would be the reason behind this?

Python Script

import cv2
import numpy as np

cam2 = cv2.VideoCapture(1)
cam2.set(cv2.CAP_PROP_CONVERT_RGB, 0);          # Request raw camera data

while True:
    b, frame = cam2.read()
    if b:
        print(frame[0,0])
        frame_16 = frame.view(dtype=np.uint16) # reinterpret data as 16-bit pixels
        frame_sh = np.right_shift(frame_16, 2)      # Shift away the bottom 2 bits
        frame_8  = (frame_sh).astype(np.uint8)        # Keep the top 8 bits       
        img      = frame_8.reshape(400, 400)        # Arrange them into a rectangle

        img = cv2.cvtColor(img,cv2.COLOR_BAYER_BG2RGB)
        cv2.imshow("Video", img)

        k = cv2.waitKey(5)

        if k & 0xFF == 27:
            cam2.release()
            cv2.destroyAllWindows()
            break

Output: frame.shape = (1,320000) and Pixel value at [0,0] is in the range of 55-68

C++

#include <stdio.h>
#include <opencv2/opencv.hpp>

using namespace std;
using namespace cv;

int main(int argc, char** argv )
{
    
    Mat frame;
    namedWindow("Display window");
    VideoCapture cam(1);

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

    cam.set(CAP_PROP_CONVERT_RGB, 0.0);          //Request raw camera data

    while (true) {
        cam.read(frame);
        // get the pointer (cast to data type of Mat)
        uchar *pImgData = (uchar *)frame.data;
        uchar value = pImgData[channels*(cols*0+0)+0];
        cout<<unsigned(value)<<endl;
        imshow("Display window", frame);
        cnt++;
        if(waitKey(1) == 'q')
        {
            destroyAllWindows();
            break;
        }
    }
    return 0;
}

Output: CV_8UC3, (400,400,3) and pixel values at 0th index is 255.