This topic is devoted to Gimp+G'MIC users' dreams, i.e. future functions/filters and/or existing filters enhancements, which may enrich this software (already excellent, but -we know- users are always willing something more, whenever possible).
The entered challenges may be (from G'MIC gurus viewpoint):
A- simple to implement (one just has to find a little time to do it...)
B- complex to implement (the horizon would be far in the future...)
C- impossible to implement (sometimes a user cannot know in advance the intrinsic limits of the software)
Should it happen that a user enters a challenge which the G'MIC author (David) considers of class C, we beg in advance his pardon...

Let me enter just my first challenge:
it was already entered in a question topic to David, but I didn't realize whether it has to be considered a type C or only a type B.

Challenge # 1
to have the possibility to "drill down" in selecting an option, i.e. to further specify an option.
Not to remain "up in the air" :
- assume you want to set a parameter in a (new) filter for which the complete list of desirable options is very big
- it is clearly "user unfriendly" to have a "choice" parameter which "explodes" in a huge list
- but you know that all those options can be "categorized" into families, so that it could be nice to have a "first level" selection where you choose among the families, then a "second level" selection were you choose among the individual options

Examples?
In my previous post I made the example of the standard international colours name; the full list is huge, but it is fractioned into classes of colours: yellow, red, brown etc
Another example could be nations; the are a lot but they are geographically classified into different areas: Europe, North America, Africa etc

In my previous post I asked whether it is (now) possible to call from inside a G'MIC filter the "previews" of other filters (the preview -as we know- shows a panel with parameters); the answer of David was "no".

I post here this request as a challenge because:
1 - I didn't realize whether the "no" means "it is impossible to implement" or simply "currently this possibility is not implemented"
2 - there maybe other (feasible? idk) solutions, like having a new type of parameter which allows a subselection (like in the filters list, for instance)

Note: because there will be many different requests under this topic, it may be useful if any subsequent challenge is numbered and if the comments are referred to the challenge number. Thanks

dinasset, it is not possible for now.
It could require quite a lot of new developments in the current plug-in code just to allow this kind of things, without mentioning the compatibility break that would happen with the current filter definition file. As we still don't know if the G'MIC plug-in will stay alive, with the upcoming versions of GIMP, I doubt someone want to put too much energy in this.
IMHO, I'm not even sure that letting a user play with hundred of parameters for a single filter is really desirable.

OK David, thanks.
I hope Gimp-G'MIC plug-in will stay!!! Do you have some bad news from Gimp people?

Not really, but the devs are clearly porting existing plug-ins to the new GEGL engine :

http://wiki.gimp.org/wiki/Hacking:Porti ... rs_to_GEGL

Not sure the current API won't break when this work will be done.

Challenge # 2
just to conclude the year (and initiate a new one) with a G'MIC challenge
this could be a special invitation for Garry...

I would like for the new year a special "blur" program in G'MIC.
Another one! someone may say...Yes, a special one.

When dealing with a noisy portrait we have available a G'MIC smoothing tool for the skin; nice. What IMO is missing is to have a smoothing tool for the hair (and now you understand why I'm thinking it's a special challenge for Garry!).
Why?
Very simple: if the original image is only a very little noisy, we may let the hair as it is, but when the noise is very disturbing then we do not have anything special for the hair.
If we try to apply one of the many smoothing filters available, each one -AFAIK- performs the smoothing effect in a somehow "circular" way, thus removing not only the noise but also the structure of the hair; a special hair smoothing filter would have to identify the structure of the hair and perform the smooth along the "lines" of the hair structure.
Something which operates in the direction of Garry's "hair lock" but having a kind of a preprocessing step which tries to identify the existing hair structure.
Then, perform the smooth in a "line" way...

For hair denoising try anisotropic smoothing with a high value of tensor smoothness.

Edit: and high Anisotropy

thanks Iain for the indications, I'll try.

edit: tried once, seen the difference, can be the temporary solution (awaiting Garry....)
thanks again Iain

challenge #3

I am a fan of antique stained glass art
Could you G'MIC gurus think it could be possible to implement a new Stained Glass filter better approaching that style?
somethink like:



thanks!

And I though I asketh for too mucheth. lololol

If it can be done, then I'm looking forward to a more realistic stained glass result too. Not sure you can duplicate the ability of a true artisan though, but I've been wrong before.

just for fun
(at least "my personal fun")
forced cobblestone filter (Graechan) to approach Stained Glass.....

Dinasset. I see your attempt very close to what you want to get. IMO, It'd be more realistic if the little pieces was almost transparent with a very soft tone. Could you get that? I mean not so opaque.

I'm with dinasset. I hope we can find a way to migrate the G'MIC plugin to GIMP 2.10 (whenever that happens). If users have to choose between 16-bit color or G'MIC, that will be a sad day.

thanks Issabella
I tried to follow as far as possible your suggestion
what about this modified version?

Yes, Dinasset. This one is closer to stained glass. As the structure of the little glass panels is very similar to the real ones. The aim is now to get that transparency and luminosity of the glass.

sorry, my friend, I guess I reached my limits with the next one
It was only a vague attempt...
Still waiting for David and/or Garry (or Graechan, if he thinks he can implement a new specialized version of his nice Cobblestone filter to be closer to Glasswork)

I think that some of our fantastic gurus in the forum will be able to help you to get that wonderful look that stained glass has. I was thinking of if the treatment that someone of them have applied to that delicate texture that veil has, could work in this topic. What do you think?

for (my) fun another attempt (still waiting....)
no cobblestone this time

Si! Si! Si! quite a lot better in my opinion, you have got translucent glassy texture similar to stained glass. I think you should go just ahead in this new direction.
Well done my friend!

@dinasset
Missed this discussion.
Here are my own pontifications on stained glass: Beginner's Cookbook: Stained Glass
This is a G'MIC command line tutorial, sans any paint program, but the key commands have been also written as Gimp-G'MIC filters, in particular -bandpass, which appears in the Gimp-G'MIC plug-in under 'Spectral Filters->Bandpass.
For about a year, we had a stained glass shop here in Park Slope, Brooklyn; the fellow sold stained glass items and gave lessons; I took a couple to satisfy my curiosity.
It is a hard craft! And it was even much harder for the medeval craftsmen.
Glass was fabulously expensive, and many of the staining metals rare. They carefully broke glass in the shape of the main masses of their compositions, but kept the shards; perhaps one day the odd shape of a shard would be apt for a particular composition. In part, that's where the variations in color comes from: the glass would be from different lots.
Here's the example I showed in the tutorial:

Some observations based on this example:

1. Glass almost never breaks in a straight line. Nor would the artisan want to because they are trying to 'draw' natural forms with it. This mitigates against Voroni, which natively consists entirely of straight line segments. My inclination would be to abandon Voroni, and use Gradient norm to capture edges, and perhaps Skeleton to break up the masses, then blur/threshold/warp to misalign straight lines; I think this is akin to approaches you have used in other attempts.
2. The cames, the lead metal used to mortise the glass, is soft and could be shaped with some heating. This endows it with a slight blobby character, as metal would mass in one place more than another, and would be especially thick at intersection points. I think one would have to blur/threshold whatever art they use to represent the cames, to soften the corners. As I discussed in the tutorial, some slight warping helps emulate the handcrafted aspect.
3. BRL on the cames might be useful. It would also give you a post or two to keep that long-running thread alive (though it seems to need no help)!
4. The etching and pigment which artisans applied directly to glass to draw faces and other fine detail is also vital to the look and feel of stained glass.
5. Dirt and other accumulations at the glacis of glass and cames is also an important aspect of stained glass. The fluctuations that bandpass applies along edges helps here, I think.

I think a stained glass Gimp-G'MIC filter that does justice to the craft will be a long time coming. You've certainly taken on a challenge here! All my remarks notwithstanding, I think you've captured many stained-glass aspects. Ah! But to get them all to play well in one composition! You have your work cut out for you!

Take care,

Garry

Thanks Garry for your info on the topic.
So, it looks that it will be a looong wait!
In the meantime I continued working on my tests...
I show you my last possible outcome.
After this point I stopped and remain...waiting!



(you see very well the limits of this implementation, but so far no better outcome for me)