It is confirmed and the algorithm has been reverse engineered, though not by looking at firmware https://w2.eff.org/Privacy/printers/docucolor/ https://w2.eff.

It is confirmed and the algorithm has been reverse engineered, though not by looking at firmware https://w2.eff.org/Privacy/printers/docucolor/ https://w2.eff.org/Privacy/printers/docucolor/ Seems like the algorithm is simple enough that they did it just by looking at some prints