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 referred to the short HTJ2K white paper, or the extended HTJ2K white paper for more details on HTJ2K. This paper explores the attainable performance on CPU, and this paper for decoding on a GPU.
OpenJPH can be compiled to Javascript. For a demo, see this. This demo also shows decoding a single HTJ2K image at multiple resolutions, a feature known as resolution scalability. The decoding process involves decoding a prefix of the file; i.e., decoding only the first x bytes of the file – the number of bytes that need to be decoded is detailed in the demo.html page.
Another project of interest is the openjphjs project, developed by Chris; at this URL you can find a nice online demonstration of javascript-based HTJ2K encoding/decoding, with a wealth of features and user-selectable options.
A newly launched website that shares interest in HTJ2K is the fittingly named htj2k.com website.
