in the "make a paisley" thread, lylejk posted a link to
this old tut, written for kai's power tools (i used to know kpt as a ps plug-in, but i think it could be used in other ways too?). i was a bit overconfident and said it should be easy enough to recreate that tut in gimp now, with the help of g'mic, but sad to say it wasn't that easy at all!
here are my two best results so far - one has better paisleys and i have done a lot of "manual" work on it between each filter step, the other is perhaps more fun to look at and i just tried to follow the tut as closely as possible without doing any touching up by hand, but i don't think the paisleys look very "paysley-y".
here are the steps i used for the second of these patterns:
1. spiral gradient from center on empty canvas, then g'mic filter "cartesian transform" under "deformations" (just to get some shapes and colours to start with, you can do that other ways too).
2. g'mic filter "kaleidoscope-symmetry" under "deformations". iterations 11, angle 0, boundaries nearest, mirror forwards or backwards.
3. layer offset by x/2, y/2.
4. "kaleidoscope-symmetry" on offset layer, set "boundaries" to transparent, otherwise the same settings as before.
5. layer offset by x - one third, y - two thirds of image size.
6. gimp filter "whirl and pinch" under "distortions". whirl angle 215, pinch amount 0, radius 0,710.
7. g'mic filter "tileable rotation" under "arrays", default settings.
(8. gimp filter "small tiles" under "map". this has nothing to do with the tutorial, i just liked this pattern better smaller)
edit: might be useful to know i worked on a 1200X1200 px canvas. the original kpt tut is written for a 100X100 px canvas.