video processing using opencv

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The access to the camera is done through HighGui module of OpenCV. Here you could find the doc for the camera access.

Just a small sample from the doc which apply a Gaussian blur, and find the edge with the Canny detector.

VideoCapture cap(0); // open the default camera
// Check the access to the camera here!

Mat edges;
for(;;)
{
    Mat frame;
    cap >> frame; // get a new frame from camera
    cvtColor(frame, edges, CV_BGR2GRAY);
    GaussianBlur(edges, edges, Size(7,7), 1.5, 1.5);
    Canny(edges, edges, 0, 30, 3);
    imshow("edges", edges);
    if(waitKey(30) >= 0) break;
}

Here you could find the doc for almost all ''simple'' image processing available with OpenCV. The rest of the doc could help you depending on what you want to do with images.