text: #include <iostream>
  #include <stdio.h>
  
  #include <opencv2/opencv.hpp>
  
  using namespace std;
  using namespace cv;
  
  /** Function Headers */
  void detectAndDisplay( Mat frame );
  
  /** Global variables */
  String face_cascade_name = "../haar_data/haar_face.xml";
  String eyes_cascade_name = "../haar_data/haar_eyeglasses.xml";
  CascadeClassifier face_cascade;
  CascadeClassifier eyes_cascade;
  string window_name = "Capture - Face detection";
  RNG rng(12345);
  
  /** @function main */
  int main( int argc, const char** argv ) {
    VideoCapture cap;
    Mat frame;
  
    //-- 1. Load the cascades
    if( !face_cascade.load( face_cascade_name ) ){ printf("--(!)Error loading\n"); return -1; };
    if( !eyes_cascade.load( eyes_cascade_name ) ){ printf("--(!)Error loading\n"); return -1; };
  
    //-- 2. Read the video stream
    if(!cap.open(0))
       return 0;
  
    while( true ) {
      cap >> frame;
  
      //-- 3. Apply the classifier to the frame
      if( !frame.empty() ) {
        detectAndDisplay( frame );
      } else {
        printf(" --(!) No captured frame -- Break!");
        break;
      }
  
      int c = waitKey(10);
      if( (char)c == 'c' )
        break;
    }
    return 0;
  }
  
  /** @function detectAndDisplay */
  void detectAndDisplay( Mat frame ) {
    std::vector<Rect> faces;
    Mat frame_gray;
  
    cvtColor( frame, frame_gray, COLOR_BGR2GRAY );
    equalizeHist( frame_gray, frame_gray );
  
    //-- Detect faces
    face_cascade.detectMultiScale( frame_gray, faces, 1.1, 2, 0|CASCADE_SCALE_IMAGE, Size(30, 30) );
  
    for( size_t i = 0; i < faces.size(); i++ ) {
      Point center( faces[i].x + faces[i].width*0.5, faces[i].y + faces[i].height*0.5 );
      ellipse( frame, center, Size( faces[i].width*0.5, faces[i].height*0.5), 0, 0, 360, Scalar( 255, 0, 255 ), 4, 8, 0 );
  
      Mat faceROI = frame_gray( faces[i] );
      std::vector<Rect> eyes;
  
      //-- In each face, detect eyes
      eyes_cascade.detectMultiScale( faceROI, eyes, 1.1, 2, 0 |CASCADE_SCALE_IMAGE, Size(30, 30) );
  
      for( size_t j = 0; j < eyes.size(); j++ ) {
        Point center( faces[i].x + eyes[j].x + eyes[j].width*0.5, faces[i].y + eyes[j].y + eyes[j].height*0.5 );
        int radius = cvRound( (eyes[j].width + eyes[j].height)*0.25 );
        circle( frame, center, radius, Scalar( 255, 0, 0 ), 4, 8, 0 );
      }
    }
    //-- Show what you got
    imshow( window_name, frame );
  }
  
  