JPEG2000

Initially the goal was to patch jasper in order to support 16bits lossless image. But due to the lack of motivation and support from the dev team, this goal was dropped.
On the other a young and motivated team at openjpeg.org manage to patch properly the lib to give exact result (same as kakadu), therefore openjpeg is the prefered open source implementation.

Ref:
[Jasper]
http://www.ece.uvic.ca/~mdadams/jasper/

[OpenJPEG]
http://www.openjpeg.org/