Left: original image. Right: filter applied.

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

This filter is found in the main menu under Filters → Enhance → Symmetric Nearest Neighbor….

Presets, Input Type, Clipping, Blending Options, Preview, Merge filter, Split view


	These options are described in .

Radius

Radius, in pixels, of square pixel region. Width and height of this region are radius*2+1:

Pairs

You can select 1 or 2 pairs: higher number preserves more acute features.