Change WPF window background image in C# code

What about this:

new ImageBrush(new BitmapImage(new Uri(BaseUriHelper.GetBaseUri(this), "Images/icon.png")))

or alternatively, this:

this.Background = new ImageBrush(new BitmapImage(new Uri(@"pack://application:,,,/myapp;component/Images/icon.png")));

Here the XAML Version

<Window.Background>
    <ImageBrush>
        <ImageBrush.ImageSource>
            <BitmapImage UriSource="//your source .."/>
        </ImageBrush.ImageSource>
    </ImageBrush>
</Window.Background>

The problem is the way you are using it in code. Just try the below code

public partial class MainView : Window
{
    public MainView()
    {
        InitializeComponent();

        ImageBrush myBrush = new ImageBrush();
        myBrush.ImageSource =
            new BitmapImage(new Uri("pack://application:,,,/icon.jpg", UriKind.Absolute));
        this.Background = myBrush;
    }
}

You can find more details regarding this in
http://msdn.microsoft.com/en-us/library/aa970069.aspx