[gdal-dev] Fwd: [OpenJPEG] OpenJPEG 2.2.0 is out ! Faster and safer.

[Even Rouault]

On mercredi 30 août 2017 00:25:46 CEST Nicholas G Lawrence wrote:
> I'm curious, why is OpenJpeg not compiled into GDAL by default? Is this a
> policy?
> 

This is mostly a technical constraint. The GDAL OpenJPEG driver requires linking against 
libopenjp2, which is the result of the compilation of the OpenJPEG source code, which is in 
its own source code repository. So this is mostly an issue of packaging choice: which optional 
dependencies you install before building GDAL. Like all other GDAL drivers that depend on 
third party libraries. Most popular binary distributions of GDAL have the openjpeg driver built 
(OSGeo4W, gisinternals, UbuntuGIS) (not necessarily against the latest libopenjp2 version)

The GDAL source code repository has historically a few copies of common dependencies (libz, 
libtiff, etc...) for conveniency on platforms where installing packaged dependencies isn't easy 
(Windows typically), but we cannot extend this practice to all dependencies, because of the 
increased maintainance cost.

Even


> Thanks,
> Nick
> 
> From: gdal-dev [mailto:gdal-dev-bounces at lists.osgeo.org] On Behalf Of Even
> Rouault Sent: Tuesday, 29 August 2017 7:37 PM
> To: gdal-dev at lists.osgeo.org
> Cc: jratike80 <jukka.rahkonen at maanmittauslaitos.fi>
> Subject: Re: [gdal-dev] Fwd: [OpenJPEG] OpenJPEG 2.2.0 is out ! Faster and
> safer.
> On mardi 29 août 2017 01:42:21 CEST jratike80 wrote:
> > N. Farah wrote
> > 
> > > The results you get when enabling multi-threading are very interesting:
> > > 
> > > 26.s to 9.9 s. Then using the work in progress you end up with 1s.
> > > 
> > > Basically a 26 times speed improvement.
> > 
> > Hi,
> > 
> > 
> > 
> > As always when you read benchmarks, you must keep the results and the
> > 
> > context together so it is clear what was tested. In this case the
> > important
> > 
> > part is that the test applies to single tiled images. They are what Kakadu
> > 
> > prefers (also in the usage examples) and it handles them splendidly by
> > 
> > utilizing the precincts. OpenJPEG has not been able to use precincts
> > 
> > (despite in a fork
> > 
> > https://lists.osgeo.org/pipermail/gdal-dev/2016-February/043650.html) and
> > 
> > therefore it has slow with single tiled images and actually useless if the
> > 
> > tile size is something like 20000 by 20000 pixels.
> > 
> > 
> > 
> > Even can say how much faster the new branch is with JPEG2000 images which
> > 
> > use 1024x1024 tiles but I suppose that the speed-up factor is much less
> > than
> > 
> > 26.
> 
> For tiled images, the GDAL OpenJPEG driver currently still read whole tiles
> (perhaps this should be re-considered at some point), so sub-tile decoding
> improvements will not help here, and you won't get more than the
> improvements done during 2.2.0, so something like 20% for openjpeg
> single-threaded (your mileage may vary), or more if you enable
> OPJ_NUM_THREADS.
> 
> 
> 
> Even
> 
> 
> 
> --
> 
> Spatialys - Geospatial professional services
> 
> http://www.spatialys.com
> 
> 
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