刚学习C#记录一下。
1、下载NuGet程序包，OpenCvSharp4, OpenCvSharp4.Extensions, OpenCvSharp4.runtime.win。

2、然后就可以愉快的图片处理了。

using OpenCvSharp;
using OpenCvSharp.Extensions;
using System;
using System.IO;
using FFmpeg.AutoGen;
using System.Threading.Tasks;
using Add;
using System.Drawing;

namespace WinFormsApp1
{
    public unsafe sealed partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();

            capture_pic();
            on_screen();
        }

        LinkedList<Bitmap> list_bit = new LinkedList<Bitmap>();
        int pic_flag = 1;

        private void capture_pic()
        {
            VideoCapture video = new VideoCapture();
            video.Open(0);    //打开摄像头

            if (!video.IsOpened())
            {
                MessageBox.Show("无法打开摄像头！！！", "提示：");
            }
            else
            {
                Task task = new Task(() =>
                {
                    while (true)
                    {
                        if (pic_flag == 1)
                        {
                            Mat mat = new Mat();
                            Mat newMat = new Mat();

                            bool bSuccess = video.Read(mat);
                            if (!bSuccess)
                            {
                                MessageBox.Show("无法读取摄像头的帧！！！", "提示：");
                            }
                            else
                            {
                                Cv2.Resize(mat, newMat, new OpenCvSharp.Size(pictureBox1.Width, pictureBox1.Height));
                                list_bit.AddLast(OpenCvSharp.Extensions.BitmapConverter.ToBitmap(newMat));
                            }

                            Thread.Sleep(100);
                        }
                    }
                });
                task.Start();
            }
        }

        private void on_screen()
        {
            Task taskShow = new Task(() =>
            {
                while (true)
                {
                    if (pic_flag == 1)
                    {
                        if (list_bit.Count == 0)
                            continue;
                        Bitmap bit = list_bit.First();
                        Invoke(new Action(() =>
                        {
                            pictureBox1.Image = bit;
                            pictureBox1.Show();
                            pictureBox1.Refresh();
                        }));
                        list_bit.RemoveFirst();
                    }
                }
            });
            taskShow.Start();
        }

        private void btn_start_Click(object sender, EventArgs e)
        {
            string pic_path = @"a.jpg";

            pic_flag = 1;

/*            Mat mat = new Mat("a.jpg", ImreadModes.Color);
            Mat newMat = new Mat();
            Cv2.Resize(mat, newMat, new OpenCvSharp.Size(pictureBox1.Width, pictureBox1.Height));
            Bitmap bitmap = OpenCvSharp.Extensions.BitmapConverter.ToBitmap(newMat);

            Cv2.ImShow("src", mat);
            Cv2.WaitKey(0);

            Invoke(new Action(()=>
            {
                pictureBox1.Image = bitmap;
                pictureBox1.Show();
                pictureBox1.Refresh();
            }));*/

        }

        private void btn_end_Click(object sender, EventArgs e)
        {
            pic_flag = 0;
        }

    }
}