private void pictureBox1_MouseEnter(object sender, EventArgs e)
    {
        pictureBox1.SizeMode = PictureBoxSizeMode.StretchImage;
        pictureBox1.Cursor = Cursors.Hand;
    }

    private void pictureBox1_MouseLeave(object sender, EventArgs e)
    {
        pictureBox1.SizeMode = PictureBoxSizeMode.Zoom;
        pictureBox1.Cursor = Cursors.Default;
    }