"Patina is a thin layer that variously forms on the surface of [metals]
or any similar acquired change of a surface through age and exposure."
It's neither efficient nor practical, but possible and fun for me. It is very much work in progress and i have to simplify lots of things before it is usable for anybody.
Don't use it on a webpage
Use it to generate art
What Patina could be used for. Pixel based effects. Games or effects or organic art. I should really add the possibility to save the generated images.