Hi Michael,
We made some tests with tiles of 1000*1000 pixels, with 10000 tiles, and
the memory used is about 112 MB for the encoding and 114 MB for the
decoding.
If you don't want to use tiles, I don't think OpenJPEG can beat the
commercial applications like Kakadu.
What standard do you follow for metadata ? OGC GMLJP2, or do you include
GeoTIFF information in a JP2 file like Luratech suggested to the JPEG
committee ?
Cheers,
François
Michael P. Gerlek a écrit :
François:
When you say "Mega-Images (-> geo-sized images)", just how big are you talking
about?
If you are in the 10-100GB range, I/LizardTech would be very interested in
talking with you about the project, and also about supporting some of the geo
metadata conventions. (Especially if you can do GB-sized data sets in less
than 1GB of RAM without requiring the image be tiled!) ((Do you have any
benchmark data you can share?)
-mpg
-----Original Message-----
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED] On Behalf Of
François-Olivier Devaux
Sent: Tuesday, February 26, 2008 12:47 AM
To: discuss@lists.osgeo.org
Subject: [OSGeo-Discuss] 'lossless' JPEG2000
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.
--------
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-demonstra
te-groundbreaking-medical-imaging-streaming-solution-at-> himss08,290686.shtml
---------
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.
-----
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.
-------------
Cheers,
François
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