[gdal-dev] HTJ2K decoding available in openjpeg master
even.rouault at spatialys.com
Sat Sep 25 04:52:41 PDT 2021
below is of potential interest for GDAL. We had related discussions when
a Grok GDAL driver was proposed. HTJ2K (ITU-T.814
https://www.itu.int/rec/T-REC-T.814-201906-I/en or JPEG2000 Part 15) is
an extension of regular JPEG2000 were the code block encoding, which is
the slowest part of JPEG2000, has been replaced by an alternative that
has the potential for being 10 times or more faster (could apparently be
30 times faster for lossless), with an increased file size of ~ 7%.
Current implementation in OpenJPEG is "only" twice faster.
I've verified that the current JP2OpenJPEG driver, when linked to
openjpeg master 2.5.0dev, can decode HTJ2K codestreams. This also works
when they are embedded in JP2 boxes (files with .jph extensions that are
similar to .jp2), which is in particular where georeferencing is encoded
(GMLJP2 boxes or GeoJP2 boxes), so theoretically we should be ready for
geospatial imagery using HTJ2K coding, if such a beast ever emerges...
This is a decode-only implementation. To play with the encoding side,
you'll have to use https://github.com/aous72/OpenJPH,
https://github.com/GrokImageCompression/grok or Kakadu
-------- Message transféré --------
Sujet : [OpenJPEG] HTJ2K decoding + github action workflows
Date : Sat, 25 Sep 2021 13:36:22 +0200
De : Even Rouault <even.rouault at spatialys.com>
Répondre à : openjpeg at googlegroups.com
Pour : OpenJPEG <openjpeg at googlegroups.com>
some good news to share about latest developments in OpenJPEG master branch:
- Aous Naman has made a great contribution by adding a HTJ2K (High
Throughput / Part-15) decoder. See
https://github.com/uclouvain/openjpeg/pull/1381 for details and
limitations. My quick experiment (see
shows a ~ x2 speed improvement in mono-threaded decompression compared
to regular Part-1 code block style.
- I've migrated most of the continuous integration target to github
action workflows. The driver for this is that Travis-CI is no longer
friendly to open source projects due to a limited small quota that was
exhausted for our project. github action workflows are naturally
inherited in forks, so you can potentially work on a branch for some
time, push in your clone, check CI results and just issue a pull request
when you're done.
My software is free, but my time generally not.
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OpenJPEG is mainly supported by : * UCL Image and Signal Processing Group (http://sites.uclouvain.be/ispgroup) * IntoPIX (www.intopix.com)
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