NIK Software (Free)
Snapseed is a mobile editing utility with a surprising amount of tools. Android provides you with basic built-in editing software, but this app goes much further. It is better in many ways and is packed with features.
This program has professional results but is easy to use, even for people who have issues working with technology. You can easily adjust exposure, contrast, highlights, shadows, and brightness.
For amateurs and professionals photo-editors
For quick adjustments, flip through a wide variety of filters all of which play with all of the alterations for you. People who know how to edit pictures can play with more technical features such a spot-removal brush.
Can undo edits
You have the ability to play around with photos as much as you would like, without losing the original image. If you are unhappy with the edits, you can easily undo changes and restore to the pre-edit version.
Easy Mobile Interface
The interface of this editor is straightforward and perfect for a mobile device. You only have to swipe left and right to control the strength of your edits. Everything is laid out in a straightforward manner, and it is simple to use. The interface isn't cluttered with a variety of features.
A Great Editing Application
This editor provides features that are more advanced than the built-in Android editor. The filters are beautiful, though some are dramatic. Although there is a slight learning curve; this app is easy to use and is perfectly designed for your touch-screen device.