Programa OpenCV C++ para detección de rostros

// CPP program to detects face in a video
  
// Include required header files from OpenCV directory
#include "/usr/local/include/opencv2/objdetect.hpp"
#include "/usr/local/include/opencv2/highgui.hpp"
#include "/usr/local/include/opencv2/imgproc.hpp"
#include <iostream>
  
using namespace std;
using namespace cv;
  
// Function for Face Detection
void detectAndDraw( Mat& img, CascadeClassifier& cascade, 
                CascadeClassifier& nestedCascade, double scale );
string cascadeName, nestedCascadeName;
  
int main( int argc, const char** argv )
{
    // VideoCapture class for playing video for which faces to be detected
    VideoCapture capture; 
    Mat frame, image;
  
    // PreDefined trained XML classifiers with facial features
    CascadeClassifier cascade, nestedCascade; 
    double scale=1;
  
    // Load classifiers from "opencv/data/haarcascades" directory 
    nestedCascade.load( "../../haarcascade_eye_tree_eyeglasses.xml" ) ;
  
    // Change path before execution 
    cascade.load( "../../haarcascade_frontalcatface.xml" ) ; 
  
    // Start Video..1) 0 for WebCam 2) "Path to Video" for a Local Video
    capture.open(0); 
    if( capture.isOpened() )
    {
        // Capture frames from video and detect faces
        cout << "Face Detection Started...." << endl;
        while(1)
        {
            capture >> frame;
            if( frame.empty() )
                break;
            Mat frame1 = frame.clone();
            detectAndDraw( frame1, cascade, nestedCascade, scale ); 
            char c = (char)waitKey(10);
          
            // Press q to exit from window
            if( c == 27 || c == 'q' || c == 'Q' ) 
                break;
        }
    }
    else
        cout<<"Could not Open Camera";
    return 0;
}
  
void detectAndDraw( Mat& img, CascadeClassifier& cascade,
                    CascadeClassifier& nestedCascade,
                    double scale)
{
    vector<Rect> faces, faces2;
    Mat gray, smallImg;
  
    cvtColor( img, gray, COLOR_BGR2GRAY ); // Convert to Gray Scale
    double fx = 1 / scale;
  
    // Resize the Grayscale Image 
    resize( gray, smallImg, Size(), fx, fx, INTER_LINEAR ); 
    equalizeHist( smallImg, smallImg );
  
    // Detect faces of different sizes using cascade classifier 
    cascade.detectMultiScale( smallImg, faces, 1.1, 
                            2, 0|CASCADE_SCALE_IMAGE, Size(30, 30) );
  
    // Draw circles around the faces
    for ( size_t i = 0; i < faces.size(); i++ )
    {
        Rect r = faces[i];
        Mat smallImgROI;
        vector<Rect> nestedObjects;
        Point center;
        Scalar color = Scalar(255, 0, 0); // Color for Drawing tool
        int radius;
  
        double aspect_ratio = (double)r.width/r.height;
        if( 0.75 < aspect_ratio && aspect_ratio < 1.3 )
        {
            center.x = cvRound((r.x + r.width*0.5)*scale);
            center.y = cvRound((r.y + r.height*0.5)*scale);
            radius = cvRound((r.width + r.height)*0.25*scale);
            circle( img, center, radius, color, 3, 8, 0 );
        }
        else
            rectangle( img, cvPoint(cvRound(r.x*scale), cvRound(r.y*scale)),
                    cvPoint(cvRound((r.x + r.width-1)*scale), 
                    cvRound((r.y + r.height-1)*scale)), color, 3, 8, 0);
        if( nestedCascade.empty() )
            continue;
        smallImgROI = smallImg( r );
          
        // Detection of eyes int the input image
        nestedCascade.detectMultiScale( smallImgROI, nestedObjects, 1.1, 2,
                                        0|CASCADE_SCALE_IMAGE, Size(30, 30) ); 
          
        // Draw circles around eyes
        for ( size_t j = 0; j < nestedObjects.size(); j++ ) 
        {
            Rect nr = nestedObjects[j];
            center.x = cvRound((r.x + nr.x + nr.width*0.5)*scale);
            center.y = cvRound((r.y + nr.y + nr.height*0.5)*scale);
            radius = cvRound((nr.width + nr.height)*0.25*scale);
            circle( img, center, radius, color, 3, 8, 0 );
        }
    }
  
    // Show Processed Image with detected faces
    imshow( "Face Detection", img ); 
}