content: import java.util.List;
  
  import org.opencv.core.Core;
  import org.opencv.core.Mat;
  import org.opencv.core.MatOfRect;
  import org.opencv.core.Point;
  import org.opencv.core.Rect;
  import org.opencv.core.Scalar;
  import org.opencv.core.Size;
  import org.opencv.highgui.HighGui;
  import org.opencv.imgproc.Imgproc;
  import org.opencv.objdetect.CascadeClassifier;
  import org.opencv.videoio.VideoCapture;
  
  class ObjectDetection {
      public void detectAndDisplay(Mat frame, CascadeClassifier faceCascade, CascadeClassifier eyesCascade) {
          Mat frameGray = new Mat();
          Imgproc.cvtColor(frame, frameGray, Imgproc.COLOR_BGR2GRAY);
          Imgproc.equalizeHist(frameGray, frameGray);
  
          // -- Detect faces
          MatOfRect faces = new MatOfRect();
          faceCascade.detectMultiScale(frameGray, faces);
  
          List<Rect> listOfFaces = faces.toList();
          for (Rect face : listOfFaces) {
              Point center = new Point(face.x + face.width / 2, face.y + face.height / 2);
              Imgproc.ellipse(frame, center, new Size(face.width / 2, face.height / 2), 0, 0, 360,
                      new Scalar(255, 0, 255));
  
              Mat faceROI = frameGray.submat(face);
  
              // -- In each face, detect eyes
              MatOfRect eyes = new MatOfRect();
              eyesCascade.detectMultiScale(faceROI, eyes);
  
              List<Rect> listOfEyes = eyes.toList();
              for (Rect eye : listOfEyes) {
                  Point eyeCenter = new Point(face.x + eye.x + eye.width / 2, face.y + eye.y + eye.height / 2);
                  int radius = (int) Math.round((eye.width + eye.height) * 0.25);
                  Imgproc.circle(frame, eyeCenter, radius, new Scalar(255, 0, 0), 4);
              }
          }
  
          //-- Show what you got
          HighGui.imshow("Capture - Face detection", frame );
      }
  
      public void run(String[] args) {
          String filenameFaceCascade = args.length > 2 ? args[0] : "../../data/haarcascades/haarcascade_frontalface_alt.xml";
          String filenameEyesCascade = args.length > 2 ? args[1] : "../../data/haarcascades/haarcascade_eye_tree_eyeglasses.xml";
          int cameraDevice = args.length > 2 ? Integer.parseInt(args[2]) : 0;
  
          CascadeClassifier faceCascade = new CascadeClassifier();
          CascadeClassifier eyesCascade = new CascadeClassifier();
  
          if (!faceCascade.load(filenameFaceCascade)) {
              System.err.println("--(!)Error loading face cascade: " + filenameFaceCascade);
              System.exit(0);
          }
          if (!eyesCascade.load(filenameEyesCascade)) {
              System.err.println("--(!)Error loading eyes cascade: " + filenameEyesCascade);
              System.exit(0);
          }
  
          VideoCapture capture = new VideoCapture(cameraDevice);
          if (!capture.isOpened()) {
              System.err.println("--(!)Error opening video capture");
              System.exit(0);
          }
  
          Mat frame = new Mat();
          while (capture.read(frame)) {
              if (frame.empty()) {
                  System.err.println("--(!) No captured frame -- Break!");
                  break;
              }
  
              //-- 3. Apply the classifier to the frame
              detectAndDisplay(frame, faceCascade, eyesCascade);
  
              if (HighGui.waitKey(10) == 27) {
                  break;// escape
              }
          }
  
          System.exit(0);
      }
  }
  
  public class ObjectDetectionDemo {
      public static void main(String[] args) {
          // Load the native OpenCV library
          System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
  
          new ObjectDetection().run(args);
      }
  }
  