How to image process the on the original image like the of the given output

I have this image Original Image:- (https://i.stack.imgur.com/O15RA.jpg) ,And after processing it above we want the following output [output image] :-(https://i.stack.imgur.com/KcA1V.jpg)

int main()
{
        // Read image
        Mat imgOffice = imread("img29.jpg");

        // Remove background using chroma keying
        Mat imgNoBg;
        double threshold = 5; // adjust as necessary
      //  cv::cvtColor(imgOffice, imgOffice, COLOR_BGR2HSV); // Convert to HSV color space
      //  cv::inRange(imgOffice, Scalar(-200, -200, -200), Scalar(150, 50, 50), imgNoBg); // Detect green color range and set as the background
        cv::inRange(imgOffice, Scalar(0, 0, 0), Scalar(50, 110, 100), imgNoBg);
      //  cv::morphologyEx(imgNoBg, imgNoBg, cv::MORPH_CLOSE, cv::getStructuringElement(cv::MORPH_ERODE, cv::Size(250, 10))); // Fill small holes in the foreground
       //  cv::morphologyEx(imgNoBg, imgNoBg, cv::MORPH_CLOSE, cv::getStructuringElement(cv::MORPH_ELLIPSE, cv::Size(150, 20)));
         cv::morphologyEx(imgNoBg, imgNoBg, cv::MORPH_CLOSE, cv::getStructuringElement(cv::MORPH_ELLIPSE, cv::Size(255, 20)));
        // Display both images
        namedWindow("image", WINDOW_NORMAL);
        namedWindow("output", WINDOW_NORMAL);
        imshow("image", imgOffice);
        imshow("output", imgNoBg);
        // imwrite("final-output1(MORPH_ELLIPSE).jpg", imgNoBg);
        // imwrite("o2.jpg", imgNoBg);
        waitKey(0);
        destroyAllWindows();
        return 0;
}

I expecting this result is When I process on the original image, the output image given above should come in the same result as this.'