Use r.mask as already done to identify your grey values only, then apply
r.mapcalc "new_raster=if(MASK,orig_raster,null())".
Christian.
--------------------------------------------------
From: "baobazz" <[email protected]>
Sent: Thursday, May 27, 2010 11:59 AM
To: <[email protected]>
Subject: [GRASS-user] Extracting grey features from an image
Hello
I've got a black and white image with some grey features on it
I'd like to create a new image containing only these features so I can
vectorize them
i think that I have to use
r.mask
r.mapcalc
or
r.reclass
r.describe raster
returns me
0-121 123 125-127 132-255
I created a mask of my image
r.mask input=image maskcats="0 thru 121" -i
-i to invert the maskcats range
Only the grey features appear.
So, my grey features seem to have the 0-121 range category of values.
Considering that, how can I manage to create a raster map based only on
these values.
I used r.reclass like this:
r.reclass input=raster output=rasterRec
0 thru 121=1 black
*=NULL
But I didn't get any good result...
Any help would be greatly appreciated!
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