[gdal-dev] OpenJPEG driver

[Guillaume Pasero]

Hi everybody,

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].

The behaviour of GDAL drivers differs on the following points :

  * 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.
  * The size of the overview at level 'n' is computed as : ovr_size =
    raster_size / 2^n , whereas it should be ovr_size = ceil(
    raster_size / float(2^n) )


I am using GDAL 1.10.1 and OpenJpeg 2.0.
Is it relevant to report a bug on this topic ?

Best Regards,
Guillaume

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