OpenCV Getting started learning to read USB camera images, real-time display

First, create a new source program file for. CPP, for example,

Gedit Test.cpp

Add the following program to the file:

#include <opencv2/core/core.hpp>    
#include <opencv2/highgui/highgui.hpp>    
using namespace CV;  
      
int main (int argc, char** argv) {
    Cvnamedwindow ("video");

    cvcapture* capture = cvcreatecameracapture (1);
    iplimage* frame;

    while (1) {
        frame = cvqueryframe (capture);
        if (!frame) break;
        Cvshowimage ("video", frame);

        char C = cvwaitkey (+);
        if (c==27) break;
    }

    Cvreleasecapture (&capture);
    Cvdestroywindow ("video");
    return 0;
}

Save exit. The compilation chain is delivered as an executable file.

g++ test.cpp-o test-i/usr/local/include/opencv-i/usr/local/include/opencv2-l/usr/local/lib/*.so

Insert Camera, run program

./test

Done.

cvcreatecameracapture (), initialize get video from camera

cvcapture* cvcreatecameracapture (int index);

If there is only one camera, the parameter value takes 0. When the parameter is set to-1, OpenCV opens a window for the user to select the camera to use.

cvqueryframe () fetches a frame from the camera or file and then extracts and returns the frame. The returned image can not be released or modified by the user.

iplimage* Cvqueryframe (cvcapture* capture);

Cvshowimage ()that is used to display the image in the specified window.

void Cvshowimage (const char* name, const cvarr* image);