How to detect a small white ball?

mainImage = new Image<Bgr, byte>("D://222.jpg");
            processedImage = mainImage.InRange(new Bgr(0, 0, 128), new Bgr(47, 47, 255));
            processedImage = processedImage.SmoothGaussian(9);
            CircleF[] circles = processedImage.HoughCircles(new Gray(100), new Gray(50), 2, processedImage.Height / 4, 4, 400).SelectMany(u => u.Select(s => s)).ToArray();
            foreach (var c in circles)
            {
                
                CvInvoke.Circle(mainImage, new Point((int)c.Center.X, (int)c.Center.Y), 3, new MCvScalar(0, 255, 0), -1, Emgu.CV.CvEnum.LineType.AntiAlias, 0);
                mainImage.Draw(c, new Bgr(Color.Red), 3);
            }
            imageBox1.Image = mainImage;
            imageBox2.Image = processedImage;

HoughCircles

InRange(new Bgr(0, 0, 128), new Bgr(47, 47, 255));