图片水印效果 出现问题了 在线等啊

        /**//// <summary>
        /// 会产生graphics异常的PixelFormat
        /// </summary>
         private static PixelFormat[] indexedPixelFormats = { PixelFormat.Undefined, PixelFormat.DontCare,
 PixelFormat.Format16bppArgb1555, PixelFormat.Format1bppIndexed, PixelFormat.Format4bppIndexed,
 PixelFormat.Format8bppIndexed
     };
 
    
 
 
         protected void Button1_Click1(object sender, EventArgs e)
         {
             if (File1.PostedFile.FileName.Trim() != "")
             {
                 //上传文件 
                 string extension = Path.GetExtension(File1.PostedFile.FileName).ToLower();
                 string fileName = DateTime.Now.ToString("yyyyMMddhhmmss");
                 string path = Server.MapPath(".");
               File1.PostedFile.SaveAs(path);
 
                 //加文字水印，注意，这里的代码和以下加图片水印的代码不能共存 
                 System.Drawing.Image image = System.Drawing.Image.FromFile(path);
                 Graphics g = Graphics.FromImage(image);
                 g.DrawImage(image, 0, 0, image.Width, image.Height);
                 Font f = new Font("Verdana", 16);
                 Brush b = new SolidBrush(Color.Blue);
                 string addText = "图片加水印";
                 g.DrawString(addText, f, b, 10, 10);
                 g.Dispose();
 
                 //保存加水印过后的图片,删除原始图片 
                 string newPath = Server.MapPath(".");
                 image.Save(newPath);
                 image.Dispose();
                if (File.Exists(path))
                {
                    File.Delete(path);
                }                Image1.ImageUrl = newPath;
                // Response.Redirect(newPath); 
            }        }        protected void Button2_Click1(object sender, EventArgs e)
        {
            //上传文件 
            string extension = Path.GetExtension(File1.PostedFile.FileName).ToUpper();
            string fileName = DateTime.Now.ToString("yyyyMMddhhmmss");
            string path = Server.MapPath(".")+"\\upload\\" + fileName + extension;
            File1.PostedFile.SaveAs(path);
            //加图片水印 
            System.Drawing.Image image = System.Drawing.Image.FromFile(path);            if (IsPixelFormatIndexed(image.PixelFormat))
            {
                Bitmap bmp = new Bitmap(image.Width, 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(image, 0, 0);
                }
            }
            else
            {
                System.Drawing.Image copyImage = System.Drawing.Image.FromFile(Server.MapPath(".") + "\\upload\\" + fileName + extension);
                Graphics g = Graphics.FromImage(image);
                g.DrawImage(copyImage, new Rectangle(image.Width - copyImage.Width, image.Height - copyImage.Height, copyImage.Width, copyImage.Height), 0, 0, copyImage.Width, copyImage.Height, GraphicsUnit.Pixel);
                g.Dispose();
            }
            //保存加水印过后的图片,删除原始图片 
            string newPath = Server.MapPath(".") + "\\upload\\" + fileName+extension;
            image.Save(newPath);出现GDI+ 中发生一般性错误。            image.Dispose();
            if (File.Exists(path))
            {
                File.Delete(path);
            }            Image1.ImageUrl = newPath;
        }        private static bool IsPixelFormatIndexed(PixelFormat imgPixelFormat)
        {
            foreach (PixelFormat pf in indexedPixelFormats)
           {
                if (pf.Equals(imgPixelFormat)) return true;
            }            return false;
        }    }帮我看看呐