Mastering OpenCV 3 - Second Edition

Accessing the webcam

To access a computer's webcam or camera device, you can simply call the open() function on a cv::VideoCapture object (OpenCV's method of accessing your camera device), and pass 0 as the default camera ID number. Some computers have multiple cameras attached, or they do not work as default camera 0, so it is common practice to allow the user to pass the desired camera number as a command-line argument, in case they want to try camera 1, 2, or -1, for example. We will also try to set the camera resolution to 640x480 using cv::VideoCapture::set() to run faster on high-resolution cameras.

Depending on your camera model, driver, or system, OpenCV might not change the properties of your camera. It is not important for this ...