I just used the default settings for that image Molly.It started out as an indexed black and white image.
I believe if the image has more contrast (such as his hat and the bg) colors.The lines of circles follow the edges more.
Actually because they are two different colors and the circles are each one solid color it seems that way to the eye.

All i did to the image was change the image mode from indexed to RGB, flattened the image.
I ran the Circlism filter after that and got those results.

So the more contrast in an image the more your going to get those type of edge results i think.

Great, thanx Rod. that last one you did turned out great.

PS MareQ
In case you already refreshed the filter overwriting that file...well i suppose you will need to ask David for a copy of the older filter code ...i bet he has a back up

@ Lylejk

your last is really cool !!

And i bet your guess right a halo cause a aument of contrast between edges and the surrounding
If that is correct also use Unsharp Mask as usually should not , to create halo should help

Thanks Molly.

Hey PC; simple unsharp mask sharpening really didn't make much of a halo. Using the Pen preset is the best I believe. Might try other experiments (no need to show my unsharp mask result) to see whats a good edge contrast change would be benificial to create more detailed results. Thanks for the comments too by the way.

OK; posting one more (my Dad this time). It took well over an hour (more like 1.5 hours) to render. Running G'MIC Pen Drawing is definitely an asset to getting edge detail quality imo.

Very Nice Lyle, did you run circlism at the default?

That's all good work but I don't have patience for the dotting here and there

The dotting is all done by the script Lorri.

Here's the settings that I used Molly (never really use the defaults; lol).

The patience comes with the waiting.Time to take a walk.

Dad, on many occasions, told my Mom that he married the only oriental without any patience. I guess I inherited her gene Rod. lol

I think i got all my patience from having 6 kids.

If you still have hair Rod, then, indeed, you are a guru of patience. lol

I got my patience from sitting in many Dr's waiting rooms, for hours on end.

Hey Lyle, I've got hair... just not on my head!

Added Diamond and square shapes to the Circlism filter in G'MIC.
Take even more time to render though

It doesn't seem to want to update to the new Circlism filter David.
I still get only values for circles.
Maybe with this new update you should rename it to the Shapilism filter.

That is quite strange, I have to look to what is going on..

Thanks David.