Have a play, the illusion is very sensitive to which colours you pick. Please let me know what settings you've used if you find any particularly effective colour combinations as I'm trying to get a list of what works and what doesn't for future creations.
Example of what it does here http://www.gimpchat.com/viewtopic.php?f=11&t=4612

Enjoy..

CODE:

#Kitaoka Spin Illusion V0.0
#Written by step7 (2012)
#Renders positional displacement illusion "Spinning Sectors"
#based on Akiyoshi Kitaoka's "Rotating Snakes"
#
#Wiring:
#None
#
#User Values:
#Just play..
#
#Contact me about the filter on Gimp Chat Forum or Mathmap Google Group
#
filter KittyRings (image in, float sectors:10-80 (30), float zoom:1-30 (8),float inner_radius:0-2 (0), float outer_radius:0-2 (1), int R1:0-255 (113),int G1:0-255 (0),int B1:0-255 (113), int R2:0-255 (0),int G2:0-255 (255),int B2:0-255 (0))v=(sectors*a/(pi*2))+(floor(log(r)*zoom)*0.5); v=v-floor(v);out=rgbaColor(0,0,0,1);if inintv(r,inner_radius,outer_radius) then if inintv(v,0.15,0.5) then out=rgbaColor(R1/255,G1/255,B1/255,1);end;if inintv(v,0.5,0.65) then out=rgbaColor(1,1,1,1);end; if inintv(v,0.65,1) then out=rgbaColor(R2/255,G2/255,B2/255,1);end;end;out end

I tried an experiment. Rather than try a bunch of colors, I wanted to see what reverse colors might show using at least one default. The first example on the left, default r1 and r2 and on the right r1 and r2 default values reversed. The second example is as noted. My eyes are not the best. I see movement in the first example and maybe a bit in the second example.

I picked the color in the second example from the Solarized palette because the color should show equally well on a black or white background.

Thanks step7. Do we copy and save this as MM?

You can just paste the code into the expressions window then hit the "Save As" button. Recommend you put it in the "mathmap\expressions\render\" folder.

Glad to see you experimenting Odin, thanks for noting a few colours for me.

I might try changing the colour selectors to L.ab seeing as this a perception based thing - that means doing some reading though as I don't know the math for Lab to RGB conversion (Mathmap only works in RGB/HSV).

Interesting the 2nd wheel barely seems to spin, even though the colours the same??, I'll have a puzzle on that one.

Extremely cool indeed. Added my own "spin" to the rendered result. Thanks a heap.

Now that's cool Lyle.
Thanks Step7.

You guys are having so much fun...very interesting PC.

I wasn't aware of the widgets, thanks PC. Modified code:

#Kitaoka Spin Illusion V0.1
#Written by step7 (2012)
#Renders positional displacement illusion "Spinning Sectors"
#based on Akiyoshi Kitaoka's "Rotating Snakes"
#
#Wiring:
#None
#
#User Values:
#Just play..
#
#Contact me about the filter on Gimp Chat Forum or Mathmap Google Group
#

filter KittyRings (image in, float sectors:10-80 (30), float zoom:1-30 (8),float inner_radius:0-2 (0), float outer_radius:0-2 (1), color colour1, color colour2)v=(sectors*a/(pi*2))+(floor(log(r)*zoom)*0.5); v=v-floor(v);out=rgbaColor(0,0,0,1);if inintv(r,inner_radius,outer_radius) then if inintv(v,0.15,0.5) then out=colour1;end;if inintv(v,0.5,0.65) then out=rgbaColor(1,1,1,1);end; if inintv(v,0.65,1) then out=colour2;end;end;out end

Definitly like your updated script better step7.

I repeat; never look into the owl's eyes. lol

cool Lyle

and looking again to your previous , i believe something similar but animated could be done "linking" (here i mean :using the MM "composer" , not coding) this filter with "Animated Sphere"

Or even "Spinning Sectors"> mirror (to get 4 sectors , as in L example on previous page )instead then 2 )>Aanimated Sphere



First you need to have mathmap installed in gimp
Then just copy the script (on a text editor , NOT a word editor but a simple text editor as Win notepad )save with "mm" extension in your mathmap "expression folder.

take care to really save with a mm extension (i.e. spinning_sectors.mm), Windows may be a bit tricky and so try to add a txt extension (as spinning_sectors.mm.txt) and may even be so nasty to hide that added txt extension
(this will happen with the default setting for " search "(accessible also from My Computer>"operation for files and folders ), to avoid file extension be hidden you should unmark the option "hide extension for commune file types )

Mathmap's official site is below Gram.

http://www.complang.tuwien.ac.at/schani/mathmap/

Believe Graechan compiled it for 64-bit (don't believe it's necessary for this plugin to be 64-bit unlike G'MIC), but way too lazy to find the link but it was a thread here that Graechan started as I recall.