Its a phenomenon called - wait for it - purple fringing and it impacts almost all digital imaging to some degree. However some cameras are more prone to experience the problem than others, and some manufacturers do a better job removing it during image processing. A few years ago, Panasonic "fixed" the problem during image processing by digitally detecting the phenomenon and making the purple area dark red. Which, a bit surprisingly, made it far less visible. The iPhone 5 had a fairly obvious problem with purple fringing, to the point where it was pretty easy to recognize a photo taken with one.
Unfortunately the HTC One M8 has a bad case of purple fringing and you are seeing it in your shots. It is most obvious when a dark part of the image is immediately adjacent to a very light part of the image, like shooting bare tree branches with a grey sky behind them.
It's probably the single worst attribute of the HTC One camera. Sketchy metering being a close second in terms of annoyance.
You can read about it here:
http://en.m.wikipedia.org/wiki/Purple_fringing
Posted via Android Central App