if (IsPixelFormatIndexed(pb.Image.PixelFormat))
                {
                    Bitmap bmp = new Bitmap(pb.Image.Width, pb.Image.Height, PixelFormat.Format32bppArgb);
                    using (Graphics g = Graphics.FromImage(bmp))
                    {
                        g.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
                        g.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
                        g.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
                        g.DrawImage(pb.Image, 0, 0);

                        string SITE_NAME = "TEST";// 繪製文字於圖像上
                        g.DrawString(AVEID, new Font("Verdana", 20), new SolidBrush(Color.Tomato), 40, 40);
                        g.DrawString(SITE_NAME, new Font("Verdana", 20), new SolidBrush(Color.Tomato), 40, 80);

                    }
                    if (Directory.Exists(textBox2.Text + @"\" + DateTime.Now.ToString("yyyyMMdd") + @"\") == false)
                        Directory.CreateDirectory(textBox2.Text + @"\" + DateTime.Now.ToString("yyyyMMdd") + @"\");
                    bmp.Save(textBox2.Text + @"\" + DateTime.Now.ToString("yyyyMMdd") + @"\" + AVEID + "_new.jpg");
                }
                else
                {
                    using (Graphics g = Graphics.FromImage(pb.Image))
                    string SITE_NAME = "TEST";// dt_excel_new.Rows[0]["SITE_NAME"].ToString();// 繪製文字於圖像上
                    g.DrawString(AVEID, new Font("Verdana", 20), new SolidBrush(Color.Tomato), 40, 40);
                    g.DrawString(SITE_NAME, new Font("Verdana", 20), new SolidBrush(Color.Tomato), 40, 80);

                    //error here
                    pb.Image.Save(textBox2.Text + @"\" + DateTime.Now.ToString("yyyyMMdd") + @"\" + AVEID + "_new.jpg");
                }
            }