I considered doing this over a year ago. I was really intrigued by the algorithm and declared it was a distraction over getting the basic app solid first.
I'd love to revisit it. It really works wonders. I've played with the CLAHE implementation in Fiji/ImageJ and while it can produce really good results, it does require some tuning.
I really admire the Camera+ guys for creating an auto tuning algorithm that is quite similar. (I'm unsure if they're using CLAHE or a variation.)
I suspect Clarity on Camera+ is some form of Contrast Limited Adaptive Histogram Equalization (CLAHE).
CLAHE came about from digital image cleanup of medical scans for human analysis.