It’s been known for a while that many printer vendors add extra hard-to-detect dots to their printouts to make a pattern that can be used to identify the source of the document later. Now a research group <http://www.theregister.co.uk/2018/06/27/german_researchers_defeat_printer_tracking_dots/> has found a way to stymie this process by adding extra dots that fit the patterns, but confuse the identification system. They even have source code on GitHub.