Related work from 2008: Mona Lisa in 50 polygons, using a genetic algorithm.[0][1] Sadly I think they refused to release their source, but I believe others have re-implemented it.
For example. Dave Hoskins (shadertoy)
To get the triangle look comment out #define ADD_DITHER and press the Compile (play) button.
https://www.shadertoy.com/view/MsX3WH
[0] https://news.ycombinator.com/item?id=4912964
[1] https://rogerjohansson.blog/2008/12/07/genetic-programming-e...