<Style x:Key="gridBeforeVisual" TargetType="Grid">
      <Setter Property="Background">
        <Setter.Value>
          <ImageBrush ImageSource="/ElecQueueMap;component/Images/BackgroundLine.png" 
                      ViewportUnits="Absolute" 
                      Viewport="0,0,676,26" 
                      TileMode="Tile"/>
        </Setter.Value>
      </Setter>
    </Style>

Rect rect = new Rect(mainGrid.RenderSize);
      RenderTargetBitmap rtb = new RenderTargetBitmap((int)rect.Right,
        (int)rect.Bottom, 96d, 96d, System.Windows.Media.PixelFormats.Default);
      rtb.Render(mainGrid);
      BitmapEncoder pngEncoder = new PngBitmapEncoder();
      pngEncoder.Frames.Add(BitmapFrame.Create(rtb));
      System.IO.MemoryStream ms = new System.IO.MemoryStream();
      pngEncoder.Save(ms);
      ms.Close();
      System.IO.File.WriteAllBytes(Directory.GetCurrentDirectory() + @"\BackgroundAll.png", ms.ToArray());

<Style x:Key="gridAfterVisual" TargetType="Grid">
      <Setter Property="Background">
        <Setter.Value>
          <ImageBrush ImageSource="/ElecQueueMap;component/Images/BackgroundAll.png"  
                      Stretch="Fill"
                      TileMode="None"/>
        </Setter.Value>
      </Setter>
    </Style>