asp.net (C #) to add a watermark effect to a picture

asp.net in the following code, the text watermark and add the image watermark code can not coexist, in order to facilitate the display before writing in a piece of
private void Btn_upload_click (object sender, System.EventArgs e)
{
if (UploadFile.PostedFile.FileName.Trim ()!= "")
{
Uploading files
string extension = Path.getextension (UploadFile.PostedFile.FileName). ToUpper ();
String fileName = DateTime.Now.ToString ("Yyyymmddhhmmss");
String path = Server.MapPath (".") + "/uploadfile/" + fileName + extension;
UploadFile.PostedFile.SaveAs (path);


Add text watermark, note that the code here and the following image watermark code can not coexist
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", 32);
Brush B = new SolidBrush (color.white);
String addtext = AddText.Value.Trim ();
g.DrawString (AddText, F, B, 10, 10);
G.dispose ();


Add Image Watermark
System.Drawing.Image Image = System.Drawing.Image.FromFile (path);
System.Drawing.Image copyimage = System.Drawing.Image.FromFile (Server.MapPath (".") + "/alex.gif");
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 ();


Save the image after the watermark, delete the original picture
String NewPath = Server.MapPath (".") + "/uploadfile/" + fileName + "_new" + extension;
Image. Save (NewPath);
Image. Dispose ();
if (file.exists (path))
{
File.delete (path);
}


Response.Redirect (NewPath);
}
}