Hi,
The very recenct additions into GDAL OpenJPEG based JPEG2000 driver makes it
possible to use totally open source software for creating JPEG2000 files which
are behaving pretty well in OpenJUMP Plus. The essential change in GDAL was to
implement the writing of GeoJP2 georeferencing metadata into GDAL "JP2OpenJPEG"
driver.
Some months ago there was a discussion about OpenJUMP ECW and JPEG2000 driver
which is based on version 3.3 of ER Mapper/Leica ECW-JPEG2000 SDK. Conclusion
was that even it is proprietary we can safely use and deliver it with OpenJUMP
now and in the future.
These two things together mean that finally we can create JPEG2000 images
without any license restrictions and we are allowed to use them in OpenJUMP and
we can also trust that we can continue with the system in the future. Trouble
with ECW is that for some years now there has not been any free applications
available for compressing. Those of us who still have old ER Mapper compressors
can continue compressing originals which are smaller that 500 MB are not
allowed to give copies to any other users. Therefore ECW is dying away from
open source users.
OpenJPEG is not as fast as Kakadu end ECW/JPEG2000 SDKs but I consider that it
is fast enough. Compressing a 420 MB aerial image with default settings takes 6
minutes with my 8 year old single processor computer. OpenJPEG driver also
seems to demand that any bigger JPEG2000 images are using internal tiling. That
is sort of a limitation but because OpenJPEG is free and open and tiling does
not make much harm it is better just take it as it is.
I will need to learn a bit more about GDAL OpenJPEG parameters and I plan to
make a tutorial about making well behaving JPEG2000 images for OpenJUMP.
-Jukka Rahkonen-
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