On 11/17/2014 07:02 PM, Andreas Neumann
wrote:
Hi,
I have a very simple task (at least I thought it is simple), but
am not able to do it properly.
I have a grayscale tiff value where I would like to replace the
value of 249 with 255 - all other values should stay as they are.
In GRASS this mapcalc _expression_ should work:
r.mapcalc "new = if(temp==247, 255, temp)"
I tried with gdal "nearblack", but nothing changed - I
started a separate email-thread about that at the gdal list.
Then I tried with the QGIS raster calculator - but it does not
support conditional syntax.
I tried with Processing and GRASS - but it would stop at 8% - the
file is quite big.
Finally I came across SAGA "Reclassify with grid value". The
dialogue is very complicated and hard to understand. After a while
it would stop with an error message telling me that Saga may not
be properly configured - but it says that it is properly
installed. Quite confusing ...
I am trying on Win7 64bit.
If the file wouldn't be so big I would try this task in The Gimp -
where it is very simple to replace one pixel values with another -
using "Select by color" and "fill with a specific color".
Any idea how I could achieve my task with GDAL, QGIS, GRASS or
Saga?
Thanks,
Andreas
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