How do I make an image stretch to fill in this WPF / XAML application?

Question

When my program displays an image which is smaller than the Image GUI object defined in XAML, it does not get stretched to fit as I would like it to. For example a 256x256

Answer 1

As many people said above here is the code for using ImageBrush. Which also sets the image while MouseOver. Thought it might helps new users.