[gdal-dev] gdal_calc.py and NoData issues

[Andreas Neumann]

oh - sorry. This helps.

Correct syntax is:
gdal_calc.py -A test.tif --overwrite --NoDataValue=99 
--outfile=testcalc.tif --calc="(A==249)*255+(A<>249)*A"

Thanks a lot!

Andreas

Am 2014-11-19 14:21, schrieb Even Rouault:
> Le mercredi 19 novembre 2014 14:16:05, Andreas Neumann a écrit :
>> Hi Even,
>> 
>> Thank you for trying to help. Unfortunately, the --overwrite option 
>> does
>> not help.
>> 
>> I have a very small test file at http://webgis.uster.ch/temp/test.tif
>> 
>> I used the following options:
>> 
>> gdal_calc.py -A test.tif --overwrite --outfile=testcalc.tif
>> --calc="(A==249)*255+(A<>249)*A"
>> 
>> All pixels with values of "255" are now "nodata" after running 
>> gdal_calc
>> ;-(
> 
> I wrote "as well", so try with "--overwrite --nodata 99".
> 
>> 
>> May I please ask you to test/verify this?
>> 
>> Thanks a lot!
>> 
>> Andreas
>> 
>> Am 2014-11-19 13:58, schrieb Even Rouault:
>> > Le mercredi 19 novembre 2014 13:49:48, Andreas Neumann a écrit :
>> >> Hi,
>> >>
>> >> I have an issue with gdal_calc.py and nodata values.
>> >>
>> >> My input data contains a lot of white pixels. After running
>> >> gdal_calc.py
>> >> with the following parameters
>> >>
>> >> gdal_calc.py -A test.tif --outfile=testcalc.tif
>> >> --calc="(A==249)*255+(A<>249)*A"
>> >>
>> >> it turns out that all pixel values with 255 are now nodata values ;-(
>> >> Is
>> >> there an option so that my 255 values are not turned into nodata? I
>> >> tested with the --NoDataValue option (e.g. 99 - which I don't use in
>> >> the
>> >> image), but it seems to be ignored. For me it is important that black
>> >> and white pixels are preserved.
>> >
>> > Use --overwrite as well, since otherwise the existing output file will
>> > be used
>> > to be just updated and not recreated.
>> > It would be appropriate that the utility warns that --NoDataValue has
>> > no effect
>> > when the output file exists.
>> >
>> >> Thanks for any hints,
>> >> Andreas
>> >> _______________________________________________
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>> >> gdal-dev at lists.osgeo.org
>> >> http://lists.osgeo.org/mailman/listinfo/gdal-dev