Instagram is the original filtered photo-sharing app, now owned by Facebook and pretty much synonymous with smartphone photography. The Android version of the app has come a long way in recent months, making it easier to improve the way your photo looks beyond just slapping a filter on top and calling it a day.
New filters are being added all the time, and for the most part they do a good job of giving photos character without stomping all over them. In addition to controlling the level of filtering, you can tweak photos' colour temperatures, adjust highlight and shadow brightness, add a vignette, sharpen and even introduce tilt-shift effects.
Google's Snapseed is one of the most accessible photo editing apps, with a wide range of features for experienced users and newcomers alike. At its most basic level, Snapseed let's you scroll vertically through image enhancement options, then drag horizontally to control the intensity of the effect.
The range of features is pretty diverse: everything from basic automatic colour and contrast enhancement to cropping and sharpening, to selectively adjusting colour properties within a particular radius. And of course it wouldn't be a photo editing app without the obligatory filters and frames, which are controlled by swiping, just like Snapseed's image tuning features.
AUTODESK PIXLR - PHOTO EDITOR
Pixlr, by Autodesk, is another powerful photo-editing app for Android, which expands upon what's offered in the Google Photos editor in a few ways. In addition to a full and very capable suite of image tubing and tweaking options — including some neat features like color splash, history brush and double exposure — Pixlr let's you add a range of artistic effects, borders, text and even stickers to your shots.
Like Snapseed and other apps, you can use Pixlr to make a good shot even better. But it's also possible to get really creative if you explore some of the more advanced capabilities.
PICSART PHOTO STUDIO
A popular, feature-rich photo editor that was formerly for Android phones only, but it's now available for iPhone.
There are several apps that let you add effects and edit your photos, but PicsArt Photo Studio does those things and quite a lot more. In fact this app has so many features it can get a little overwhelming -- particularly with the number of interface elements on the screen.
PHOTO EDITOR BY AVIARY
There are a lot of simple editors out there that handle basic filters and focus shift kind of edits for free, but most of these apps are either tied to a social network (Instagram, for example) or just aren't flexible enough to be worth having on your phone. Aviary takes the filter fans and increases the quality by an order of magnitude, offering a clean and simple UI that focuses on letting the user quickly zoom in an make edits without interrupting the artistic thought in process.
Edits happen through a simple bar across the bottom of the app, making it so you can can make one-handed on-the-fly edits as you walk down the street and get back to what you're doing. It's a lightweight photo editing app for sure, but the focus on a simple UI with straightforward tools and a boatload of effects make it hands down the most powerful simple editor.
Retrica is yet another app with its own take on turning your smartphone into a retro-grade camera, but where filters are concerned, it blows many of its competitors out of the water. In fact, it contains more filters than I even knew existed (80 in total, 55 in the free version), a randomization mode, a blur effect, a timer and even interval shooting.
Though it's not going to have the expansive tools for image editing found in some other apps, Retrica is perfect for smartphone shutter-bugs looking for filter options you can apply without a lot of hassle.
You might think of Google+ as a social network, first and foremost, however the Photos app bundled with it has a host of useful features to help you get the most out of your pictures. You can automatically backup your photos and videos to Google's cloud, making them available on every Android device you own, and view highlights of each day, so you don't need to scroll through all your photos to find the best ones.
One of Google Photos' best features is Auto Awesome, which you might have also seen in Google+ on the web. Take a bunch of photos and it'll periodically "gift" you enhanced versions of them to sit alongside the originals in your collections — think animated GIFs if you've taken a burst shot, Instagram-style filters and contrast-boosted versions of washed-out shots. Take a series of images from different perspectives and you might even end up with an auto-generated Panorama based on these pics.