How to Reduce Size of Barcode Font in ASP.Net C#

i want to reduse the size of barcode image in this code . i tried to reduce 

but its cutting the number ...  how can i reduce the size of this barcode image

   string barCode = TextBox2.Text;
            System.Web.UI.WebControls.Image imgBarCode = new System.Web.UI.WebControls.Image();
            using (Bitmap bitMap = new Bitmap(barCode.Length * 40, 80))
            {
                using (Graphics graphics = Graphics.FromImage(bitMap))
                {
                    Font oFont = new Font("IDAutomationHC39M", 16);
                    PointF point = new PointF(2f, 2f);
                    SolidBrush blackBrush = new SolidBrush(Color.Black);
                    SolidBrush whiteBrush = new SolidBrush(Color.White);
                    graphics.FillRectangle(whiteBrush, 0, 0, bitMap.Width, bitMap.Height);
                    graphics.DrawString("*" + barCode + "*", oFont, blackBrush, point);
                }
                using (MemoryStream ms = new MemoryStream())
                {
                    bitMap.Save(ms, System.Drawing.Imaging.ImageFormat.Png);
                    byte[] byteImage = ms.ToArray();

                    Convert.ToBase64String(byteImage);
                    imgBarCode.ImageUrl = "data:image/png;base64," + Convert.ToBase64String(byteImage);
                }
                plBarCode.Controls.Add(imgBarCode);

            }