Use Custom Background Image for Application

If you want to use a custom image for your application background, you can set this as follows:

<phone:PhoneApplicationPage >
  ...
  <Grid x:Name="LayoutRoot">
    <Grid.Background>
      <ImageBrush ImageSource="/Images/YourImage.jpg"></ImageBrush>
    </Grid.Background>
    ...
  </Grid>
</phone:PhoneApplicationPage>

Some things to note:

• Make sure the Image has the Build Action set to Content.
• Make sure the Images folder is at the application root level.
• Having your own background and colour combination will have the same look across both Light and Dark themes.