i was thinking to make some changes to the Graphic Novel filter:
mainly add ,in the merging mode modulo a "swap layers" option and modify the merging modes choice,. that at the moment include mixed several "swapped" and not swapped modes.

I could do that easily...i planned also to add some "escape" option to allow to visually control the intermediate steps but there i stumbled in some obstacles, so maybe i will let this in my wishlist for a while

Anyway a still hypotetical new version would include all which offered by the previous and some more,so would be even more flexible
but on the other hand willl broke , or a least force to manually edit all the old presets.

and it is maybe not intuitive when use the "swap layers" option...but 2swap" more then double the effect possible when merging:

It may sound a eresy but i may assure that swap layers change a lot also when are used commutative modes (i.e. Lighten only , multiply ,screen):
in commutative modes the order of the layer doesn't matter AT 100% OPACITY.. on the contrary more the opacity of the merging mode is lowered more become relevant the layer positions, more dramatically swap layers would change the final result

(all this talk about layers and merging because basically Graphic Novel create and merge 2 variant of the original, 1 is a clone or a variant with strecthed contrast, 2 is a pencil sketch, or a inkwash effect or anything in between.
then the layers are merged )


well adding this should be easy...i should do it ?

I'd say go for it since you say it would be easy.

Also, how hard would it be to duplicate the original layer? I keep forgetting to do that and have to undo and start over.

it is not hard at all but is not a filter but a generic gmic option



you may use "new active layers"
there is also a "new layer" option there but with "new layer" option the original remain the active layer, so mayber you will prefer "new active layers"

Go for it PC!

Thank Rod!

@O
In any case is not needed undo and redo
In case "copy" + Undo (undo never undo "copy" )+ paste as new layer
...if the filter was slow and/ or didn't preserve last settings used , copy+undo+paste as new layer will be quicker

I can't wait to check out the new filter. These filters you create are great.