Help - Need a photo editing app to distort image?

Hi all - hopefully right section.
After discovering an app that does most of what I need on the go with iPhone4 - Iris Photo Suite (not spam, just a superb app that went free for a short while last week) - the last thing I think I need to do with some images is to distort (or more so UN distort) them like I can in Photoshop. Kinda like this:



Anyone know any app that will do this? I use a variety of apps to take and edit photos but I can't find one that can free-transform. Probably a bit of a tall order I know but worth a shout out to see if anyone has an idea of an app that may do it.

Thanks for any pointers!