Once upon a time the idea of editing photos on a phone or tablet was considered folly – akin to painting watercolours on a piece of sponge. But that all changed as screens got sharper and touch control more precise. Plus, with many of us now using smartphones as our main camera, there's no shortage of raw material on them that could benefit from a bit of judicious tweaking before posting to Facebook or Instagram. There are hundreds of photo-editing apps out there clamouring for your attention, but the dozen you'll find listed below are the best we've tried so far.

Can we draw the following conclusion?
Watercolor painting on a sponge is foolish.