Upload picture and correct file extension.

protected void Button1_Click(object sender, System.EventArgs e)
{
 // Specify the path on the server to save the uploaded picture to. MUST END WITH A TRAILING SLASH!
 string SavePath = Server.MapPath("PictureFolder\\");
 if ((FileUpload1.HasFile == true)) {
  //Get the correct file extension.
  string PictureFileExtension = GetPictureFileType(ref FileUpload1);
  if (PictureFileExtension != ".UNKNOWN") {
   int fileSize = FileUpload1.PostedFile.ContentLength;
   if ((fileSize < 2097152)) {
    //Delete any previously uploaded pictures with this name.
    System.Collections.ObjectModel.ReadOnlyCollection PictureFiles = My.Computer.FileSystem.GetFiles(SavePath, FileIO.SearchOption.SearchTopLevelOnly, Now.ToString("'Picture'yyyyMMddhhmmssfffffff") + PictureFileExtension);
    if (PictureFiles.Count > 0) {
     for (ushort P = 0; P <= PictureFiles.Count - 1; P++) {
      System.IO.FileInfo FileData = My.Computer.FileSystem.GetFileInfo(PictureFiles.Item(P));
      if (FileData.Extension != PictureFileExtension) {
       My.Computer.FileSystem.DeleteFile(FileData.FullName, FileIO.UIOption.OnlyErrorDialogs, FileIO.RecycleOption.DeletePermanently);
      }
     }
    }
    SavePath += Now.ToString("'Picture'yyyyMMddhhmmssfffffff") + PictureFileExtension;
    FileUpload1.SaveAs(SavePath);
    Response.Write("The picture was uploaded successfully.");
   } else {
    Response.Write("The picture was not accepted because it exceeds 2 megabytes in size.");
   }
  } else {
   Response.Write("The file was not a picture that can be displayed by this system.");
  }
 } else {
  Response.Write("You did not specify a picture to upload.");
 }
 Response.Flush();
}

public static string GetPictureFileType(ref FileUpload UploadedFile)
{
 string functionReturnValue = null;
 if ((UploadedFile.PostedFile.ContentType == null)) {
  return ".UNKNOWN";
  return functionReturnValue;
 }
 switch (UploadedFile.PostedFile.ContentType.ToLower) {
  case "image/gif":
   return ".GIF";
  case "image/jpeg":
   return ".JPG";
  case "image/pjpeg":
   return ".JPG";
  case "image/x-png":
   return ".PNG";
  case "image/jpg":
   return ".JPG";
  case "image/bmp":
   return ".BMP";
  case "image/x-wmf":
   return ".WMF";
  default:
   return ".UNKNOWN";
 }
 return functionReturnValue;
}