Tag: streaming

Tutorial: Real time QR Code / Bar code detection using webcam video feed / stream using OpenCV and ZBar

Pre-requisites:

You will need to have installed OpenCV and ZBar (see previous tutorials) for this to work.

Source on Github:  https://github.com/ayoungprogrammer/WebcamCodeScanner

Code:

 #include <opencv2/highgui/highgui.hpp>  
 #include <opencv2/imgproc/imgproc.hpp>  
 #include <zbar.h>  
 #include <iostream>  
 using namespace cv;  
 using namespace std;  
 using namespace zbar;  
 //g++ main.cpp /usr/local/include/ /usr/local/lib/ -lopencv_highgui.2.4.8 -lopencv_core.2.4.8  
 int main(int argc, char* argv[])  
 {  
   VideoCapture cap(0); // open the video camera no. 0  
   // cap.set(CV_CAP_PROP_FRAME_WIDTH,800);  
   // cap.set(CV_CAP_PROP_FRAME_HEIGHT,640);  
   if (!cap.isOpened()) // if not success, exit program  
   {  
     cout << "Cannot open the video cam" << endl;  
     return -1;  
   }  
   ImageScanner scanner;   
    scanner.set_config(ZBAR_NONE, ZBAR_CFG_ENABLE, 1);   
   double dWidth = cap.get(CV_CAP_PROP_FRAME_WIDTH); //get the width of frames of the video  
   double dHeight = cap.get(CV_CAP_PROP_FRAME_HEIGHT); //get the height of frames of the video  
   cout << "Frame size : " << dWidth << " x " << dHeight << endl;  
   namedWindow("MyVideo",CV_WINDOW_AUTOSIZE); //create a window called "MyVideo"  
   while (1)  
   {  
     Mat frame;  
     bool bSuccess = cap.read(frame); // read a new frame from video  
      if (!bSuccess) //if not success, break loop  
     {  
        cout << "Cannot read a frame from video stream" << endl;  
        break;  
     }  
     Mat grey;  
     cvtColor(frame,grey,CV_BGR2GRAY);  
     int width = frame.cols;   
     int height = frame.rows;   
     uchar *raw = (uchar *)grey.data;   
     // wrap image data   
     Image image(width, height, "Y800", raw, width * height);   
     // scan the image for barcodes   
     int n = scanner.scan(image);   
     // extract results   
     for(Image::SymbolIterator symbol = image.symbol_begin();   
     symbol != image.symbol_end();   
     ++symbol) {   
         vector<Point> vp;   
     // do something useful with results   
     cout << "decoded " << symbol->get_type_name() << " symbol "" << symbol->get_data() << '"' <<" "<< endl;   
       int n = symbol->get_location_size();   
       for(int i=0;i<n;i++){   
         vp.push_back(Point(symbol->get_location_x(i),symbol->get_location_y(i)));   
       }   
       RotatedRect r = minAreaRect(vp);   
       Point2f pts[4];   
       r.points(pts);   
       for(int i=0;i<4;i++){   
         line(frame,pts[i],pts[(i+1)%4],Scalar(255,0,0),3);   
       }   
       //cout<<"Angle: "<<r.angle<<endl;   
     }   
     imshow("MyVideo", frame); //show the frame in "MyVideo" window  
     if (waitKey(30) == 27) //wait for 'esc' key press for 30ms. If 'esc' key is pressed, break loop  
     {  
       cout << "esc key is pressed by user" << endl;  
       break;   
     }  
   }  
   return 0;  
 }  

To Test

Find any QR code or bar code and hold it close to your webcam and it should pick up.