[gdal-dev] gdal_calc.py and NoData issues

[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
> >> _______________________________________________
> >> gdal-dev mailing list
> >> gdal-dev at lists.osgeo.org
> >> http://lists.osgeo.org/mailman/listinfo/gdal-dev



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