opencvsharp canny 多线程计算后将所有找到的点合并找圆心参数从外往内找圆心、从白边起找圆心、高精度亚像素，请编写c#函数

以下是使用OpenCvSharp实现的Canny多线程计算后找圆心的C#示例代码：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using OpenCvSharp;

namespace CannyCircleDetection
{
    class Program
    {
        static void Main(string[] args)
        {
            Mat src = Cv2.ImRead("test.png", ImreadModes.Grayscale);

            // 双边滤波去噪
            Mat blurred = new Mat();
            Cv2.BilateralFilter(src, blurred, 9, 75, 75);

            // Canny边缘检测
            Mat edges = new Mat();
            Cv2.Canny(blurred, edges, 50, 200);

            // 多线程计算
            Point[][] contours;
            HierarchyIndex[] hierarchy;
            Cv2.FindContours(edges, out contours, out hierarchy, RetrievalModes.Tree, ContourApproximationModes.ApproxSimple);

            // 合并所有点
            List<Point> allPoints = new List<Point>();
            foreach (var contour in contours)
            {
                allPoints.AddRange(contour);
            }

            // 从外往内找圆心
            Point2f center;
            float radius;
            Cv2.MinEnclosingCircle(allPoints.ToArray(), out center, out radius);
            Console.WriteLine("Center: ({0}, {1}), Radius: {2}", center.X, center.Y, radius);

            // 从白边起找圆心
            Mat whiteEdges = new Mat();
            Cv2.Threshold(edges, whiteEdges, 127, 255, ThresholdTypes.BinaryInv);
            Cv2.FindContours(whiteEdges, out contours, out hierarchy, RetrievalModes.Tree, ContourApproximationModes.ApproxSimple);
            allPoints.Clear();
            foreach (var contour in contours)
            {
                allPoints.AddRange(contour);
            }
            Cv2.MinEnclosingCircle(allPoints.ToArray(), out center, out radius);
            Console.WriteLine("Center: ({0}, {1}), Radius: {2}", center.X, center.Y, radius);

            // 高精度亚像素
            Mat gray = new Mat();
            Cv2.CvtColor(src, gray, ColorConversionCodes.BGR2GRAY);
            Cv2.GaussianBlur(gray, gray, new Size(9, 9), 2, 2);
            Cv2.HoughCircles(gray, HoughMethods.Gradient, 1, 20, 200, 50, 0, 0);
            foreach (Vec3f circle in circles)
            {
                Point center = new Point((int)circle[0], (int)circle[1]);
                int radius = (int)circle[2];
                Cv2.Circle(src, center, radius, Scalar.Green, 2);
            }

            Cv2.ImShow("Result", src);
            Cv2.WaitKey(0);
            Cv2.DestroyAllWindows();
        }
    }
}

这段代码包含了三个不同的圆心计算方法，分别是从外往内找圆心、从白边起找圆心、高精度亚像素。你可以根据需要选择一种或多种方法。