OK; this one's for Diego. You folks know I hate doing these. lolol

Step one: your target (picture of a Christmas cactus flower I took a few years back).



Step two: Run Isophotes:



Now run Mosaic Helper (not showing screen shot)

Now stroke the resulting path with a dot.

Result of the stroke:



Threshold the dots (turns out you can do this; I didn't play with this when I tried when I first started rendering these as I should; tried to convert to 2-bit but that didn't work. Saving as PBM and then using the result does work, but apparently Threshold works too so this is the better way of doing this):



Once you do this, run Skeleton (quick):

Now convert the result of your Isophotes to all black (dup, top layer set to darken and merge down):



Invert the Skeleton result and merge the Isophotes black to create the mask:



Now colorize the cells (mask on top; target on bottom):

OK; the result (resized and embellished; not going to do a tut on that).

Lyle: cannot find Mosaic helper. Where do I find it?

Check thread below, Pat. Rob posted it there (a few replies down).

viewtopic.php?f=9&t=2714

thanks a lot Lyle, today I will try to repeat your steps and see what I can get !

Hope to see what you can come up with Diego. My bet is this can all be done withing G'MIC, but Rob's mosaic creator is just a great Script-fu for doing this.

I don't know.
My problem is arriving to the phase where all lines(paths) are converted to dots, i.e. arriving to have a layer which does only show "designing" dots. I'm terribly incompetent with paths.
Anyhow, I'll try again later.

Lyle, Thank you very much for this nice tutorial to get such a bright result. You make many people grow in knowledge and be thankful for that.
Here your tut in PDF.

thanks Issabella, easier to read and follow the instructions.
Still unable to get designing dots....
Maybe someone else can try to run this tut ?
If she/he succeeds, can she/he detail each substep done starting from the isophoted image to arrive to the dot-shaped image?

maybe (but only maybe) these could be the substeps after having run Isophotes:
- select a transp pixel on the outcome (to get the shapes otherwise RobA script takes the contours of the image to start drawing paths)
- run RobA script with defaults (paths are created according to the shapes)
- invert selection (to have the Isophotes drawing lines selected)
- cut (to remove the isophotes drawing lines)
- select all
- stroke the path with solid colour 1 px and line type "sparse dots"
- fill with White everything except the dots (either of these two ways: add a White layer below and merge down the dots layer, or select again the transparent pixels and fill with White)
- delete the path
- threshold the dots
- run Skeleton
- (at least in my case) run Repair Inpaint Holes (I had a pixel inside each Tile)

I got something which looks like a base to continue

I tried last night and could not get the dots.

Need to stroke the resulting path with a 1 pixel brush with 800 to 1500px spacing Pat. The path is created by Rob's Mosaic helper. You then need to Threshold the pixels per the tutorial.

That's how it will look like, but you also need to blend back the Isophotes step, Diego (of course this needs to be inverted for the mask to work with Testing>lylejk>Blend (Shape Average) for the colorizing step.

Lyle: Tried it again but I am missing something. Is each step a new layer? or do we do several steps on 1 layer? I tried several ways but did not get the dots, and when I did skeleton, just got a black layer.

Once you stroke your paths, you then need to use threshold to make the dots all black (since they won't me). After that, run Skeleton preset, Pat.

Pat, Wallace, did you try to follows also my substeps for going after Isophotes to Skeleton?