Mastering OpenCV 3 - Second Edition

Main camera processing loop for a desktop app

If you want to display a GUI window on the screen using OpenCV, you call the cv::namedWindow() function and then 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 base 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); } // ...