[gdal-dev] 16 bit / px / band TIFFs unreadable by ImageMagick, others

[Frank Warmerdam]

Nissim Chudnoff wrote:
> Hello all,
> 
> I've been having odd issues using GeoTIFFs made with GDAL that have 16
> bits per band RGB data. These images can be read by some software (GDAL,
> OpenEV) but not others (ImageMagick, GeoServer, IrfanView), so I can't
> tell if there's some problem with the file such that only GDAL works right
> (IIRC, OpenEV uses GDAL) or just that everyone else has crappy support of
> such files. Here's the commandline I used to generate the GeoTIFF:

Nissim,

I'm not clear in what way ImageMagick, GeoServer and IrfanView fail
to read the file in question.  I looked at it and it does not seem
particular odd.

Things that will reduce the number of programs supporting it:

  1) It's tiled.  Some programs still don't support tiled tiff files.

  2) It's 16bit.  Lots of programs don't support 16bit tiff files.

  3) It uses only a fraction of the 16bit dynamic range.  Lots of programs
     that *can* read 16bit assume the image is full dynamic range (values
     from 0 to 65535 so your image in the 0 to 1000 range (roughly) will end
     up getting shown as black and slightly off black.

Images not intended for remote sensing images are unlikely to display the
image in question nicely but I don't see anything really wrong with it.

Best regards,
-- 
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