This portrait is painted by Epenko. A painting robot developed by Sander Idzerda. Epenko could not have existed without friend Floris van Manen. http://www.epenko.com/wp-content/uploads/2017/04/Epenko-setup-and-strategy-information.pdf
video 1, Epenko robot painting darker regions
Epenko robot painting lighter regions, more towards the end of the painting process. Beacuse of the visual feedback toe robot correct mistakes made earlier like regions / strokes that came out too dark.
Information about the Epenko setup and strategy (pdf)