Изменение разрешения изображения - C#

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
 
namespace WindowsFormsApplication1
{
    public partial class Form1 : Form
    {
        public Form1()
        {
            InitializeComponent();
        }
        Bitmap j;
        private void exitToolStripMenuItem_Click(object sender, EventArgs e)
        {
            DialogResult rsl = MessageBox.Show("Вы действительно хотите выйти из приложения?", "Внимание!", MessageBoxButtons.YesNo, MessageBoxIcon.Question);
            if (rsl == DialogResult.Yes)
            {
                Application.Exit();
            }
        }
 
        private void bMPToolStripMenuItem_Click(object sender, EventArgs e)
        {
            LoadImage(false);
        }
 
        private void jPEGToolStripMenuItem_Click(object sender, EventArgs e)
        {
            LoadImage(true);
        }
 
        private void toolStripButton2_Click(object sender, EventArgs e)
        {
            LoadImage(false);
        }
 
        private void toolStripButton3_Click(object sender, EventArgs e)
        {
            LoadImage(true);
        }
        private void LoadImage(bool jpg)
        {
            openFileDialog1.InitialDirectory = "c:";
            if (jpg)
            {
                openFileDialog1.Filter = "image (JPEG) files (*.jpg)|*.jpg|All files (*.*)|*.*";
            }
            else
            {
                openFileDialog1.Filter = "image (BMP) files (*.bmp)|*.bmp|All files (*.*)|*.*";
 
            }
            if (openFileDialog1.ShowDialog() == DialogResult.OK)
            {
                try
                {
                    j = (Bitmap)Image.FromFile(openFileDialog1.FileName);
                    pictureBox1.Size = new Size(j.Width, j.Height);
                    pictureBox1.Image = Image.FromFile(openFileDialog1.FileName);
                }
                catch (Exception ex)
                {
                    MessageBox.Show("Не удалось загрузить файл: " + ex.Message);
                }
 
            }
        }
        private void changeSizeToolStripMenuItem_Click(object sender, EventArgs e)
        {
            if ((toolStripHeigth.Text == "") & (toolStripWidth.Text == ""))
            {
                MessageBox.Show("Enter width and heigth of picture!");
            }
            else
            {
                Bitmap Image = new Bitmap(j, Convert.ToInt32(toolStripWidth.Text), Convert.ToInt32(toolStripHeigth.Text));
                j = Image;
                pictureBox1.Size = new Size(Image.Width, Image.Height);
                pictureBox1.Image = Image;
            }
        }
        private void changeAllowingToolStripMenuItem_Click_1(object sender, EventArgs e)
        {
            if ((toolStripTextBoxHeight.Text == "") & (toolStripTextBoxWidth.Text == ""))
            {
                MessageBox.Show("Enter width and heigth of picture!");
            }
            else
            {
                j.SetResolution(Convert.ToInt32(toolStripTextBoxWidth.Text), Convert.ToInt32(toolStripTextBoxHeight.Text));
                pictureBox1.Image= j;
            }
        }
 
        private void saveToolStripMenuItem_Click(object sender, EventArgs e)
        {
            if (pictureBox1.Image != null)
            {
                SaveFileDialog savedialog = new SaveFileDialog();
                savedialog.Title = "Сохранить картинку как ...";
                savedialog.OverwritePrompt = true;
                savedialog.CheckPathExists = true;
                savedialog.Filter = "Image Files(*.BMP)|*.BMP|Image Files(*.JPG)|*.JPG|All files (*.*)|*.*";
                if (savedialog.ShowDialog() == DialogResult.OK)
                {
                    try
                    {
                      j.Save(savedialog.FileName, System.Drawing.Imaging.ImageFormat.Jpeg);
                    }
                    catch
                    {
                        MessageBox.Show("Impossible to save image", "FATAL ERROR",
                        MessageBoxButtons.OK, MessageBoxIcon.Error);
                    }
                }
            }
        }
    }
}