These days everyone seems to want instagram-style filters for images on iPhone. The way to do this (I think) is to examine how people have implemented equivalent filters in Photoshop and code them in objective c. Unfortunately, the imaging libraries are all geared for gaming. For non-game developers who just want simple image processing, this is overkill. The problem with my curves implementation is that I didn't use the same kind of curve algorithm as Photoshop uses. Mainly, because I don't know how, and other than the name of the curve (bicubic) all the posts and documentation I simply don't understand or cannot figure out how to port to iOS. But, the curves I use (catmull-rom) seem close enough.