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Hi everybody,<br>
<br>
I am using the OpenJPEG driver from GDAL and I noticed some
differences with the behaviour of an other OpenJPEG "driver" that I
used before in the library Orfeo ToolBox. The GDAL driver fails to
pass a conformance test : using the input file
"jpeg2000_conf_p1_06.j2k" , reading the resolution level 4 (zero
being the original image) , it should produce a 1x1 image with the
pixel value [195, 36, 100].<br>
<br>
The behaviour of GDAL drivers differs on the following points :<br>
<ul>
<li>The number of overviews detected for a jpeg2000 dataset is
limited (no overview if its dimensions are both lower than 256).
Even if the the overviews can be computed by GDAL, it won't use
the wavelet coefficients for the highest levels, but rather
perform the default nearest neighbor interpolation.</li>
<li>The size of the overview at level 'n' is computed as : <tt>ovr_size
= raster_size / 2^n</tt> , whereas it should be <tt>ovr_size
= ceil( raster_size / float(2^n) ) </tt><br>
</li>
</ul>
<br>
I am using GDAL 1.10.1 and OpenJpeg 2.0.<br>
Is it relevant to report a bug on this topic ?<br>
<br>
Best Regards,<br>
Guillaume<br>
<br>
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<b>Guillaume PASERO</b><br>
Ingénieur d'études et développement<br>
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<b>Business Unit E-SPACE & Geo Information</b></a><b>
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href="mailto:guillaume.pasero@c-s.fr">guillaume.pasero@c-s.fr</a>
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