COLOUR printers are now so good that crooks can use them to counterfeit bank
notes and share certificates. To foil them, a manufacturer has developed a
forensic marking technology that will give each colour printer an invisible
fingerprint, making it as identifiable as the print hammers on a manual
typewriter.
Patents filed by Hewlett-Packard (GB 2361211) explain how the operation of a
printer’s yellow laser drum—or ink-jet print head—can be
microscopically marked with a unique code that can be spread over several
printed characters. As only one pixel in each character cell is altered, and the
eye is…
