If you want to display a GUI window on the screen using OpenCV, you call the cv::namedWindow() function and then the cv::imshow() function for each image, but you must also call cv::waitKey() once per frame, otherwise your windows will not update at all! Calling cv::waitKey(0) waits forever until the user hits a key in the window, but a positive number such as waitKey(20) or higher will wait for at least that many milliseconds.
Put this main loop in the main.cpp file, as the basis of your real-time camera app:
while (true) {
// Grab the next camera frame.
cv::Mat cameraFrame;
camera >> cameraFrame;
if (cameraFrame.empty()) {
std::cerr<<"ERROR: Couldn't grab a camera frame."<<
std::endl;
exit(1);
}
// Create a blank output image, that we will draw onto.
cv::Mat displayedFrame(cameraFrame.size(), cv::CV_8UC3);
// Run the cartoonifier filter on the camera frame....