The home page describes Kakadu thus: A comprehensive, heavily optimized, fully compliant software toolkit for JPEG2000 developers
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DataCompression.info user Tim A. gushed: A very fast implementation with a small memory footprint compared to Jasper and even other commercial implementations. Also handles large files better than all others I have tried. Very well done with motion JPEG2000, a viewer and a JPIP server to boot (and those are just the sample applications!). John J. added The best of any JPEG2000 compressors for lossless compression. Higher compression rates, and faster compression than Aware and Algo Vison Luratech.

http://www.kakadusoftware.com/