Pic-Tap-Go, an app created by the makers of Rad Lab, is definitely on the top of my list of photo-editing apps. I have tried several out, but I always come back to this one for these reasons-it's easy and quick. With Pic-Tap-Go I apply my filter(s), use the slider to adjust the opacity of each, and I hit save. The app is incredibly user friendly.
On the left, is the original photo. On the right, I applied the "Brightside" filter. You can see that the darkness, especially around the face area, is brighter and more natural looking. Here is another before-and-after using just the "Brightside" filter:
The entire photo here is brightened, making for a more natural and cleaner photo, however I want to take it one filter further using the "Loft" filter at about a 60% opacity:
I find that this particular filter really enhances a fair complexion and I use it often when I feel like doing a little bit more than just brightening the photo.
Another way that I use this app, is to upload a photo to Instagram without cropping it into a square. This comes in particularly handy when I want to share my scrapbook layouts.
I simply tap "Instagram-Full" and I am taken directly to Instagram. So simple and solves the problem of how to share a photo that is not a square ;).
Wishing you a great week!