DocuColor Tracking Dot Decoding Guide

October 17, 2005 | Cryptography, Security | By: Mark VandeWettering

Xerox printers use a watermarking technique to insert codes onto all printed documents from their Docucolor color laser printers. These identify date, time and printer serial number with a grid of yellow dots which appear in the printout. Presumably these codes are inserted to make the job of the Secret Service simpler in tracking their use in creating counterfeit money. What’s kind of cool though is that the EFF has figured out how to decode them. Interesting bit: the dots are simple to see when viewed under an intense blue light, like one of those blue Photon LEDs.


Comment from Mark
Time 10/17/2005 at 12:56 pm

This is just a test message. Posting was broken, so I hope this fixes is.