iPhone 5 camera.

I'm really impressed with this thing. My photos are coming out super sharp. And I'm really impressed with the low light and how it handles it. I think they did a fantastic job. I'm curious about one thing though. When you take a shot it looks like the photos get letter boxed and they aren't optimized to fit the entire scene of the iPhone5. Does anyone know why that is? I would imagine it would be nicer if the photo fit the entire screen.