Hi,
Someone should just tell the team at ESA (are you reading us ESA by the
way?) in charge of producing those JPEG2000 files to turn on the Kakadu
switch to generate TLM markers. A 5 minute change on their side, ok
maybe 1 hour to update unit tests.
What you suggest about sidecar .tlm sidecar could certainly be
implemented, but one would have to rescan the archive to generate them.
At that point, you'd probably just want to insert the TLM marker inside
existing files with a dedicated utility that wouldn't need to decompress
the pixel values.
See also https://mastodon.social/@EvenRouault/113556023446290151 for an
alternate idea (not necessarily better).
Even
Le 13/12/2024 à 16:50, Jérémy Anger via gdal-dev a écrit :
Dear GDAL maintainers,
Thank you for the release of OpenJPEG 2.5.3, with the support of TLM
markers!
Following up on [1], Sentinel-2 JP2 files currently do not have TLM
markers. However, it is theoretically possible to generate an external
index file for each JP2 raster, and the index could be formatted
exactly as a JP2 TLM marker. Such sidecar file is not part of the
JPEG2000 standard, but given the gains that are achievable with TLM
markers, this strategy sounds reasonable. The entirety of the
Sentinel-2 collection (archive and live) is concerned.
GDAL could be modified to look for these sidecar .tlm files (although
I'm not too familiar with the sidecar system), and give the TLM marker
content to JP2 implementations (OpenJPEG in particular, after changes).
Do you think this approach is reasonable? Would it be reasonable to
implement such a feature in GDAL and OpenJPEG?
Do you have ideas for a better solution?
Best regards,
Jérémy
[1]: https://lists.osgeo.org/pipermail/gdal-dev/2024-November/059805.html
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