It's amazing how many useful features are making it to iPhone apps. In particular, photo apps for the iPhone get more and more remarkable as time goes on. PhotoForge2 is a US$2.99 app that allows you to load your photos at full resolution, and it includes high-end features like layering and masking, curves, levels, sharpening and noise reduction, white balance, RAW image import, the ability to edit GPS and IPTC photo data, channel mixer controls and much more.
This would be a nice collection of features for a Mac app. It's rather amazing this is an app running on a cellular phone. In practice, the app works rather well. I found the controls easy to manipulate on the iPhone's small screen, and I could zoom all the way into my image to see individual pixels. The app has 30 different filters, including a good black and white translation and sepia tones. You can send photos via email and the various social services. Check the gallery for some screen shots of editing sessions and a look at the GUI.
Alas, no app is perfect. Photos can't be loaded unless your phone has location services switched on. Frankly, this is a silly requirement. Apple requires developers to get permission when accessing location data, even data that is already tagged on your phone, but I think there are ways around this; the developers say they have some workarounds coming, perhaps as early as this weekend. When editing. changing settings can also be frustrating. When adjusting curves and levels, for example, you can barely see your image because the controls cover it. There is a software switch to hide the controls, but that makes the adjustments a needless iterative process. Also, an in-app purchase of $1.99 is needed for some additional features. I really dislike that practice and would prefer to get everything, even if it raises the price of the app.
There is no iPad version of this app yet, and editing on a larger screen would really be a more satisfying experience. The developer tells me it's coming, and it will be a free update for owners of the current app. Look for it in 3-4 weeks.
In summary, PhotoForge2 is a very powerful app. It has a few GUI kinks, but the feature set is awesome. It does a lot of things that similar apps just don't do, and I'm confident the app will continue to grow and thrive. If you're away from your computer and want to do some semi-sophisticated image editing, PhotoForge2 is worthy of your attention. The app requires iOS 4.2 or later. It runs on the iPod touch and the iPad, but the resolution is not native on the iPad, so hold out for that update.