iOS: Polarr is an already popular photo-editing app that offers the functionality of desktop photo-editing suites, and this latest update uses new facial recognition algorithms to make touch ups easier and faster than ever. Photo by Andy Orin.
It actually uses the facial recognition API that Apple created for iOS 10. That means that the app can instantly recognise faces in your photos, and can then do things like whiten teeth, smooth skin, adjust tone and brighten eyes and lips. It's like having a little fashion photographer in your phone who is judging your selfies and offering a helping hand. You don't even have to select each face in a photo; it just recognises multiple faces automatically.
All the other standard features of photo-editing apps are there too, of course, if you just want to adjust the white balance or saturation. In fact, the editing options are all surprisingly thorough, and there's a slight learning curve to navigating the interface -- if only because there are so many features. Luckily, Polarr includes a wide, horizontal interface so you can turn your phone on its side to maximise the size of the photo you're editing and actually see what you're doing. And it's free. You'll need iOS 10 to take advantage of the new facial features but it will otherwise work on older versions.