[GRASS-user] reduce cells around the perimeters of all areas

[Hamish]

pierluigi de rosa wrote:
> 
> I need to reduce the area in a raster map. I should do something
> similar to the opposite of r.grow. I tried a method combinig r.null
> and r.neighbors (option minimum) but maybe it exist a better way to
> do this.

use r.mapcalc to make a "negative" mask, then use r.grow, then r.mapcalc
again to make a positive from the grown negative.


Hamish