The camera is one of the main reasons I purchased an HTC One (M7), with its awesome low-light performance, so I was really bummed when my pictures started getting a weird purple tint around the edges. The problem got progressively worse, to the point that the camera was essentially unusable:
So, I did some digging online and, while my case is abnormally serious, the purple picture problem seems to be a common issue for HTC Ones that were manufactured early on in their product run (I preordered mine and got it right at launch). No one is exactly sure what causes the problem, but people suspect it's related to heat, either in the phone itself or specifically at the "ultrapixel" camera sensor. Either way, replacing the camera module supposedly fixes it, and there have been reports of individuals sending their phones in for other warranty issues and getting them back with newer camera modules, whether they reported purple pics or not.
In my case, I went down to the local Sprint affiliate and inquired about a camera replacement. The tech started an insurance report and found that 'camera takes purple pictures' was one of the pre-defined claims, so he was able to order a refurbished phone for me on the spot at no cost (not even an insurance deductible!). A couple days later, I received my new phone and its camera works as well as I remembered. I'll update this post if it starts showing the same issues.
