learnopencv/FaceDetectionComparison/face_detection_opencv_haar.cpp

#include "opencv2/objdetect.hpp"
#include "opencv2/videoio.hpp"
#include "opencv2/highgui.hpp"
#include "opencv2/imgproc.hpp"

#include <iostream>
#include <stdio.h>

using namespace std;
using namespace cv;

/** Global variables */
String faceCascadePath;
CascadeClassifier faceCascade;

void detectFaceOpenCVHaar(CascadeClassifier faceCascade, Mat &frameOpenCVHaar, int inHeight=300, int inWidth=0)
{
    int frameHeight = frameOpenCVHaar.rows;
    int frameWidth = frameOpenCVHaar.cols;
    if (!inWidth)
        inWidth = (int)((frameWidth / (float)frameHeight) * inHeight);

    float scaleHeight = frameHeight / (float)inHeight;
    float scaleWidth = frameWidth / (float)inWidth;

    Mat frameOpenCVHaarSmall, frameGray;
    resize(frameOpenCVHaar, frameOpenCVHaarSmall, Size(inWidth, inHeight));
    cvtColor(frameOpenCVHaarSmall, frameGray, COLOR_BGR2GRAY);

    std::vector<Rect> faces;
    faceCascade.detectMultiScale(frameGray, faces);

    for ( size_t i = 0; i < faces.size(); i++ )
    {
      int x1 = (int)(faces[i].x * scaleWidth);
      int y1 = (int)(faces[i].y * scaleHeight);
      int x2 = (int)((faces[i].x + faces[i].width) * scaleWidth);
      int y2 = (int)((faces[i].y + faces[i].height) * scaleHeight);
      rectangle(frameOpenCVHaar, Point(x1, y1), Point(x2, y2), Scalar(0,255,0), (int)(frameHeight/150.0), 4);
    }
}


int main( int argc, const char** argv )
{
    faceCascadePath = "models/haarcascade_frontalface_default.xml";
    if(!faceCascade.load(faceCascadePath))
    {
        printf("--(!)Error loading face cascade\n");
        return -1;
    }

    VideoCapture source;
    if (argc == 1)
        source.open(0, CAP_V4L);
    else
        source.open(argv[1]);  Mat frame;

    double tt_opencvHaar = 0;
    double fpsOpencvHaar = 0;

    while (true)
    {
        source >> frame;
        if (frame.empty())
            break;

        double t = cv::getTickCount();
        detectFaceOpenCVHaar(faceCascade, frame);
        tt_opencvHaar = ((double)cv::getTickCount() - t)/cv::getTickFrequency();
        fpsOpencvHaar = 1/tt_opencvHaar;

        putText(frame, format("OpenCV HAAR ; FPS = %.2f",fpsOpencvHaar), Point(10, 50), FONT_HERSHEY_SIMPLEX, 1.3, Scalar(0, 0, 255), 4);

        imshow("OpenCV - HAAR Face Detection", frame);

        int k = waitKey(5);
        if(k == 27)
        {
            destroyAllWindows();
            break;
        }
    }
}