Converting barcode into image file format

Color BackColor = Color.White;
            String FontName = "IDAutomationSC128M DEMO";
            string Fontaname1 = "ARIAL";
            int FontSize = 11;
            int fontSize1 = 8;
            int Height2 = 80;
            int Width2 = 175;
           string a,b,c;
           IDAutomationBarcodeObject = new clsBarCode();
            a = IDAutomationBarcodeObject.Code128(txtEnter.Text, true);
            b = "Some Sample Name";
            c = "Product Description";

            Bitmap bitmap = new Bitmap(Width2, Height2);
            Graphics graphics = Graphics.FromImage(bitmap);
            Color color = Color.Gray; ;
            Font font = new Font(FontName, FontSize);
            Font Font1 = new Font(Fontaname1, fontSize1);

            SolidBrush BrushBackColor = new SolidBrush(BackColor);
            Pen BorderPen = new Pen(color);

            Rectangle displayRectangle1 = new Rectangle(new Point(0, 0), new Size(Width2 - 1, Height2 - 2));

            graphics.FillRectangle(BrushBackColor, displayRectangle1);
            graphics.DrawString(b, Font1, Brushes.Black, 0, 0);
            graphics.DrawString(a, font, Brushes.Black, 4, 15);
            graphics.DrawString(c, Font1, Brushes.Black, 0, 63);

            pictureBox1.Image = bitmap;
            bitmap.Save("c:\\button11.bmp", System.Drawing.Imaging.ImageFormat.Bmp);