Perfect to clean up BIG png cut,(i.e my favourite Poser renders often more then WP size ) but may be useful also for more little renders ,
the script will require Unsharpmask2 or gmic (gmic unsharp )

what should automate

1 Layer/transparency/selection to alpha
2 selection/invert
3 selection/grow (1px no more no less )
4 gaussian blur , default 8 , possible user value : 0(here 0=SKIP) or >0
5 selection/grow =1px
6 gaussian blur , default 4 , possible user value : 0 (here 0 = SKIP ) OR 1:2 of 4
7 selection/grow =1px
6 gaussian blur , default 2 , possible user value : 0 (here 0 = SKIP ) OR 1:2 of 6
7 selection/grow =1px
8 selection/invert
9 selection/shrink=1 px
9 selection/feather=2 px
10 Unsharpmask2 ( or gmic Unsharp ) if possible call in iterative mode BUT with a preset
(for sure this is possible with GMIC "unsharp" not sure if is possible with the Unsharp2 plugin )
11 Select /none
12 Output = active layer OR new layer
13 only IF Output = new Layer ,
Layer modes =1 Normal , 2 Soft Light , 3 Multiply , Opacity >0 , default 75

(13 may help much for render "faded" by dramatic scaling down, sometimes i saved so renders to scale down from 10 to 1 )

Any help ?
are a lot of boring steps to do manually but the result is excellent , very often it not only give smooth and clean edges but also add lot of depth more (a sort of DOF effect but the blur is not consciously perceptible because just allow a better merge with the BG, while unsharp mask make the rest pop out )

----------------------
note at the first gaussian blur step often the blur is applied or to ...nothing or to fringes, the other 2 gaussian blur steps instead blur only the most extreme periphery then there is a seamless transition with the sharpening effect

Again this works well on BIG png cut, but if little it is usually just needed to skip 1 blur step

(yes i giving away all my secret formula )

please..help

I just recently started with Python-fu. There are much better scripters out here surely...

I was wandering if i can do as Gmic filters

The problem is that gmic can do directly much on selection, but anyway may read and edit the alpha channels and create and use (internally) mask and that may be equivalent

But in those days i really can set my mind in coding, for me is always difficult but now will be even more ...