I was looking around for a HSL filter for Pixel Bender – found a few HSV implementations but none for HSL, so I went ahead and implemented it based on an algorithm on wikipedia.

Unfortunately, the base-line image looked slightly brighter than it should be. I suspect it could be a rounding error. So before I post the source to pixel bender exchange, please take a look and let me know it could be refined.

Download HSL kernel with source code