public static void FindContours(InputOutputArray image, out Point[][] contours,
out HierarchyIndex[] hierarchy, RetrievalModes mode, 
ContourApproximationModes method, Point? offset = null);

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using OpenCvSharp;
using OpenCvSharp.Extensions;
namespace OpenCvSharp_03
{
  class Program
  {

    static void Main(string[] args)
    {
      
      Mat srcImage = Cv2.ImRead(@"D:\MyData\circle.jpg");     
      Mat dst_Image = MyFindContours(srcImage);
      Cv2.ImShow("srcImage:", srcImage);
      Cv2.ImShow("contours", dst_Image);
      Cv2.WaitKey();

    }
    public static Mat MyFindContours(Mat srcImage)
    {
      //轉(zhuǎn)化為灰度圖
      Mat src_gray = new Mat();
      Cv2.CvtColor(srcImage, src_gray, ColorConversionCodes.RGB2GRAY);

      //濾波
      Cv2.Blur(src_gray, src_gray, new Size(3, 3));

      //Canny邊緣檢測(cè)
      Mat canny_Image = new Mat();
      Cv2.Canny(src_gray, canny_Image, 100, 200);

      //獲得輪廓
      Point[][] contours;
      HierarchyIndex[] hierarchly;          
      Cv2.FindContours(canny_Image,out contours,out hierarchly, RetrievalModes.Tree,ContourApproximationModes.ApproxSimple,new Point(0,0));

      //將結(jié)果畫(huà)出并返回結(jié)果
      Mat dst_Image = Mat.Zeros(canny_Image.Size(),srcImage.Type());
      Random rnd = new Random();
      for (int i = 0; i < contours.Length; i++)
      {
        Scalar color = new Scalar(rnd.Next(0,255),rnd.Next(0,255),rnd.Next(0,255));
        Cv2.DrawContours(dst_Image, contours, i, color, 2,LineTypes.Link8, hierarchly);
      }
      return dst_Image;
    }
  }
}