[gdal-dev] Default progression order in JP2OpenJPEG driver

[Jukka Rahkonen]

Even Rouault <even.rouault <at> spatialys.com> writes:


> I've done a few tests encoding a RGB BMNG tile (21600x21600) with the 
> JP2OpenJPEG driver with different block size (1024, 4096, 16384), with 
> precincts, and with the PCRL, LRCP and RPCL progression orders. Using a 16384 
> large tile requires a huge amount of RAM with openjpeg (at least
16384*16384*3 
> = 800 MB, but perhaps twice or third times that when counting temporary 
> buffers)

OpenJPEG begins to be fast enough for practical use with tiled JPEG2000.
Unfortunately it is almost unusable with single tile images like the ones in
the directory below. Images are open data, only attribution required:
National Land Survey of Finland, 2014.

http://kartat.kapsi.fi/files/orto/etrs-tm35fin/mavi_vv_25000_50/2014/M52/10m/1/

Let's hope that OpenJPEG developers will discover some day how to read
single-tile images at reasonable speed. Now I cannot imagine that I would
use OpenJPEG driver even for converting such images with gdal_translate.
There is a free-as-in-beer solution by using JP2ECW read-only driver for
JPEG2000->GeoTIFF conversion followed by use of JP2OpenJPEG driver for
GeoTIFF->tiled JPEG2000 but that does not make my open source minded soul happy.

-Jukka Rahkonen-