Hello David,
> Silvio, do you have a webpage or something related (a URL) that I could use to put you in the list of contributors ?
I don't own any webpage (or URL).
My full name is: Silvio Grosso (thanks ! ) :-)
> As there is a limit in the number of output layers, the filter (layer to colors) does not have the time to output the layer with the red circle, because before reaching the corresponding pixels, it has already detected pixels with at least 16 different colors, and when the maximum number of layers is reached, it stops the decom
BTW, in order to try to extract my red color circle I have tried to increase to 32 the number of maximum layers in the filter layer to colors.
As soon as I have applied this change (32 layers as maximum number), my computer went completeley crazy (It completely freaked out ):-)
Everything stopped working: even the clock stopped running (it was stucked at 20:30 time...) and the ctr+alt+del (task manager) to Kill Gimp (G'mic) didn't work either.
In the end, after more than 10 minutes, while I was totally unable to run anything, I had to shut down my Windows 7 system altogether :-)
EDIT:
This nasty crash *always* occurs: the "color to layers filter" starts running (to try to insert the 32 layers in tha stack) and, in just a few seconds, it stops also Windows 7 - 64 bit (taskmgr is not working either and you are forced to shut down the system...).
CPU Intel I7 2630QM (plus I have 8 Gb Ram and Geforce GT 540M GPU)
With Krita 2.9 the "split layer" option takes around 20-30 seconds with this same jpeg image (Windows 7 - 64 bit as usual).

Maybe, on Windows (64 bit), this filter should be modified in order to *not* allow (tpye in the filter box) to insert more than a certain amount of layers (just in case some user wants to experiment with its settings...). Or, perhaps, today, you have already fixed this same problem (I am referring to your message regarding Windows long integer still coded with 32 bits) ? :-)