ลด/เพิ่ม ขนาด รูป auto ให้เท่ากับ Picturebox ทำไงครับ

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 ImageGallery
{
    public partial class ViewForm : Form
    {
        private Image theImage;

        public ViewForm(Image MyImage)
        {
            InitializeComponent();

            theImage = MyImage;

            this.ClientSize = new System.Drawing.Size(theImage.Width + 24, theImage.Height + 24);
            ViewPictureBox.Size = new System.Drawing.Size(theImage.Width, theImage.Height);
        }

        private void ViewForm_Load(object sender, EventArgs e)
        {
            ViewPictureBox.Image = null;
            ViewPictureBox.SizeMode = PictureBoxSizeMode.CenterImage;
            ViewPictureBox.Image = theImage;
        }

        private void ViewPictureBox_Click(object sender, EventArgs e)
        {
            this.Close();
        }
    }
}