This filter blurs the image preserving edges. It is very effective in noise reduction maintaining sharp edges.
It works comparing each pixel to its neighboring pixels and to 1 or 2 pairs of symmetric pixels around the center.
 
          4 symmetric pairs
| ![[Nota]](images/note.png)  | Nota | 
|---|---|
| These options are described in Secção 2, “Common Features”. | 
Radius, in pixels, of square pixel region. Width and height of this region are radius*2+1:
 
              
You can select 1 or 2 pairs: higher number preserves more acute features.