Mastering OpenCV with Practical Computer Vision Projects

Main camera processing loop for a desktop app

If you want to display a GUI window on the screen using OpenCV, you call cv::imshow() 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 indefinitely 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 main_desktop.cpp, as the basis for 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 ...