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