ImageBrush has its Stretch property set to Fill: image is expanded to completely fill the rectangle.
<Page xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" x:Class="Microsoft.Samples.Graphics.UsingImageBrush.TilingExample" > <Grid Margin="20"> <Rectangle Grid.Row="6" Grid.Column="1" Width="300" Height="150" Stroke="MediumBlue" StrokeThickness="1" HorizontalAlignment="Left"> <Rectangle.Fill> <ImageBrush Stretch="Fill" ImageSource="c:\image.jpg" /> </Rectangle.Fill> </Rectangle> </Grid> </Page>