Kakadu

JPEG 2000 SDK, includes encoder/decoder
Homepage:	http://www.kakadusoftware.com/
License:	Commercial, binaries freely available for non-commercial use (certain restrictions apply)

Description

From the author's website: "A comprehensive, heavily optimized, fully compliant software toolkit for JPEG2000 developers."

User Experiences

Used by a number of national libraries: http://wiki.opf-labs.org/display/JP2/Example+JP2+profiles