[OSGeo-Discuss] 'lossless' JPEG2000

[François-Olivier Devaux]

Hi,

Norman Vine has pointed to me this discussion about JPEG 2000, and I 
thought it might be interesting to give you a small overview on JPEG 
2000 and present the OpenJPEG library on which we are working.

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FIELDS WHERE JPEG 2000 IS USED

JPEG 2000 is becoming the reference in image compression for 
professional applications, where precision and flexibility is really 
necessary.

The most know field using JPEG 2000 is Digital Cinema, where JPEG 2000 
has been favored against MPEG2 and H.264. Linked to that field, High 
Quality Broadcast applications are also turning to JPEG 2000 because of 
its quality and scalability (low resolution versions can be extracted 
directly from a high resolution sequence without any re-encoding, and 
JPEG 2000 sequences are encoded in intra which eases video editing).

More close to your field is Archiving, where we are feeling a trend to 
select JPEG 2000 as compression algorithm
http://www.egov.vic.gov.au/index.php?env=-inlink/detail:m1780-1-1-8-s-0:l-9669-1-1--

Medical imaging applications, where lossless compression is a important 
requirement, are also taking full advantage of JPEG 2000 remote browsing 
possibilities (with the JPIP protocol)
http://www.earthtimes.org/articles/show/aware-inc-to-demonstrate-groundbreaking-medical-imaging-streaming-solution-at-himss08,290686.shtml

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JPEG 2000 FEATURES

The JPEG 2000 features that are interesting for GeoSpatial Imagery is of 
course the ability to achieve lossless compression, the scalability 
(lower quality and resolutions as well as spatial areas can be extracted 
from a compressed file, without the need of decompression the entire 
file), the high precision (most codecs can at least handle 16 bits per 
component, and up to 256 components) and the fact that the core coding 
system can be obtained free of charge.
JPEG 2000 also has an inherent robustness higher than most compression 
schemes (JPEG, ...) and a great protocol to interactively remotely 
browse images called JPIP.

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OPENJPEG

OpenJPEG, is an open-source JPEG 2000 library. It has been very recently 
remodeled by the CNES and the french company CS to meet the requirements 
of applications using Mega-Images (-> geo-sized images). Independent 
access to tiles has been improved, in order to increase the library 
encoding and decoding performances. This new version should be made 
accessible to users at the beginning of March. We are very happy of the 
performances of this new version, and are open to new contributions.
Regarding other JPEG 2000 open source solutions in your field, the GDAL 
library has a JPEG 2000 module that is based on Jasper, which is a great 
library, but has unfortunately not evolved for the last years.

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Cheers,

François