The iPhone and iPad have really pushed developers to have more and better features for editing photos on mobile devices. I've used and been impressed with apps like Photoforge, PhotoStudio, PhotoWizard and more.
Today I've been using and testing Luminance, which adds some clever functions for serious iOS photographers. First and foremost is the ability to add layers of adjustments to photos. While not the first app to do this, it's intuitive to add effects as layers, which can be removed or made transparent so other effects can show through. Another nice feature is the ability to save any effect as a preset, then apply it to other photos that you import. If you really like to tweak your images and have taken a lot of steps as you add to the original image, Luminance gives you unlimited undos, so you can walk the image back, or jump to any particular change and pick up from there. It's a powerful feature for an app designed to run on a phone and tablet. There are quite a few presets built in, and they can be modified to taste.
As I edited my photos, the app was solid and speedy. I didn't see any crashes or bad behavior. The operation of the app is intuitive, and the developers say they were aiming for a blend between an iOS app and Lightroom or Aperture. I think they achieved that.
There are some things I'd like to see, like some built-in help, even thought the app is very easy to use. I'd also like more tools, especially rotate and cropping. Posting to Twitter is coming soon, and I'm told users can look forward to Flickr posting, tilt/shift effects, and creating frames.
I like Luminance because it pushes the editing envelope a bit, and I'm anxious to see how it evolves and improves. I've added it to my iPhone photo tool kit. Check our galleries for some shots of the app in action.
Luminance is US$0.99, which is a sale price until August 23.