I got my inspiration from https://ct.de/yrzv, however i wanted to use only an ESP8266. I came upon https://github.com/skx/esp8266, however i resented the idea of inventing yet another image format when http://netpbm.sourceforge.net/doc/pbm.html has been around for decades (and i also loathe php).
So - this happened: included is the code for the ESP8266 (upload it with the Arduino IDE for example) and a python script for creating the Image. The third thing is a bash snippet for converting PNG to PBM.