Face_Detection.cpp

OpenCV C++ Program for Face Detection
// 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 );
}