Image scrolling similar to Angry Birds?

Hi,

I'm looking for a custom image scrolling similar to how it works in Angry Birds level selection. They have one full image and two half images from both sides.

Can't achieve this with simple UIScrollView and paging enabled, as it scrolls half the page with.

Any idea how did they do it?

Thanks in advance.

Edit: damn, wrong place, can mods please move to Developer general section please?