PictureBox PictureBox1 = new PictureBox();
Button Button1 = new Button();

private void InitializePictureBoxAndButton()
{

    this.Controls.Add(PictureBox1);
    this.Controls.Add(Button1);
    Button1.Location = new Point(175, 20);
    Button1.Text = "Stretch";
    Button1.Click += new EventHandler(Button1_Click);

    // Set the size of the PictureBox control.
    this.PictureBox1.Size = new System.Drawing.Size(140, 140);

    //Set the SizeMode to center the image.
    this.PictureBox1.SizeMode = PictureBoxSizeMode.CenterImage;

    // Set the border style to a three-dimensional border.
    this.PictureBox1.BorderStyle = BorderStyle.Fixed3D;

    // Set the image property.
    this.PictureBox1.Image = new Bitmap(typeof(Button), "Button.bmp");
}

private void Button1_Click(System.Object sender, System.EventArgs e)
{
    // Set the SizeMode property to the StretchImage value.  This
    // will enlarge the image as needed to fit into
    // the PictureBox.
    PictureBox1.SizeMode = PictureBoxSizeMode.StretchImage;
}