OpenCVsharp4でPDFファイルの漫画データーの文字画像だけを切り取り。

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;
using OpenCvSharp;
using OpenCvSharp.Extensions;
using OpenCvSharp.UserInterface;

namespace OpenCVsharp4
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }

        private void button1_Click(object sender, EventArgs e)
        {
            //漫画のデーターを読み取ります。
            Mat image = new Mat(@"C:\Users\Yamada\Pictures\test.jpg", ImreadModes.Color);
            //Mat image = new Mat(@"C:\Users\Yamada\Pictures\test.pdf", ImreadModes.Color);
            //Mat image = new Mat(