MatをFormのpictureBoxに表示

BitmapConverterを使ってimageに指定するのが味噌

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using System.Windows.Forms;

// 以下を追加
using OpenCvSharp;
using OpenCvSharp.CPlusPlus;
using OpenCvSharp.Extensions;       // Bitmap変換に必要
using System.Diagnostics;

namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button_imageLoad_Click(object sender, EventArgs e)
        {
            Mat matOrgImage = new Mat(@"C:\Users\hoge\Pictures\hogehoge.jpg");
            Mat matDispImage = new Mat();
            CvSize size = new CvSize(pictureBox1.Width, pictureBox1.Height);     // formのpicture boxのサイズにあわせた
            Cv2.Resize(matOrgImage, matDispImage, size);

            Image image = BitmapConverter.ToBitmap(matDispImage);

            pictureBox1.Image = image;
        }
    }
}