public void TestFrontalFaceDetector()
        {
            const string imagePath = "images\\lenna.bmp";

            using (var window = new ImageWindow())
                using (var image = new Array2dUchar())
                    using (var detector = new FrontalFaceDetector())
                    {
                        var bmp = new System.Drawing.Bitmap(imagePath);
                        image.SetBitmap(bmp);
                        image.PyramidUp();
                        window.SetImage(image);
                        OpenCvSharp.Cv2.WaitKey(Cv2WaitKeyDelay);
                        var rects = detector.DetectFaces(image, -0.5);
                        foreach (var rect in rects)
                        {
                            Console.WriteLine(rect);
                        }
                    }
        }