OpenJPH is an open-source implementation of HTJ2K encoder and decoder; the code is developed by Aous Thabit Naman, and is released under the 2-clause BSD license. HTJ2K is also known as JPEG2000 Part 15, ISO/IEC 15444-15, and ITU-T.814. The .jph file extension has been designated to this format, from which the name of the implementation is derived.
The interested reader is refered to HTJ2K white paper for more details about HTJ2K.
A newly launched website that shares interest in HTJ2K is the fittingly named htj2k.com website.