Cast IControl to System.Windows.Controls.Image

In a WPF I need to work with a System.Windows.Controls.Image to do some transformation with it, convert it to a Bitmap and some other stuff and for that I need to cast the IControl obtained by TestLeft to an actual System.Windows.Controls.Image.

 

How can I do that? A regular cast just throws an exception.

 

Thank you!

 

P.S: I use C# for TestLeft.