continous coupled cellular automaton in OpengGL/GLSL exported to full colour RGB24 PPM image, with edge detection
median cut in C exporting each of the colours to its own black on white PGM image (this one had 5 colours)
potrace from bi-level bitmap to monochrome vector SVG image, one per colour
geany text edited the 5x SVGs into one SVG document with some pattern fill defs, changed the fill of each layer to one of the patterns, added stroke.
inkscape converted to PDF
okular displayed PDF
gimp took screenshot
TODO: shell script to automate it
TODO: make more patterns to fill with
Pattern fills in PDF output by `inkscape` are broken somehow. They disappear at low zoom in Okular and are not printed.
Using `rsvg-convert` seems to work better.
```
rsvg-convert input.svg --dpi-x 72 --dpi-y 72 -f pdf > output.pdf
```
DPI setting is necessary to get correct output page size, despite the SVG being measured in pt as output by potrace.
