FaceDetection.cpp

#include <iostream>

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

int main(int argc, char *argv[]) {
  cv::String faceCascadeFileName = "./cascade.xml";
  cv::String windowName = "Face detection";
  cv::String imageFileName = "./lenna.png";
  cv::CascadeClassifier faceCascade;
  cv::Mat face;
  cv::Mat faceGray;
  std::vector<cv::Rect> faceRects;

  if (!faceCascade.load(faceCascadeFileName)) {
    return -1;
  }

  face = cv::imread(imageFileName, 1);
  if (face.empty()) {
    return -1;
  }

  cv::cvtColor(face, faceGray, cv::COLOR_BGR2GRAY);
  cv::equalizeHist(faceGray, faceGray);

  faceCascade.detectMultiScale(faceGray, faceRects, 1.1, 2, 0 | cv::CASCADE_SCALE_IMAGE, cv::Size(30, 30));

  for (size_t i = 0; i < faceRects.size(); i++) {
    cv::Point center(faceRects[i].x + faceRects[i].width / 2, faceRects[i].y + faceRects[i].height / 2);
    cv::ellipse(face, center, cv::Size(faceRects[i].width / 2, faceRects[i].height / 2), 0, 0, 360, cv::Scalar(255, 0, 255), 4, 8, 0);
  }

  cv::imshow(windowName, face);
  cv::waitKey();

  return 0;
}