Users of recent versions of image editors, such as Adobe Photoshop or Paint Shop Pro, discovered that these also refuse to print banknotes. According to an article in Wired magazine, the banknote detection code in these applications, called the Counterfeit Deterrence System (CDS), was designed by the Central Bank Counterfeit Deterrence Group and supplied to companies such as Adobe as a binary module. However, experiments by Steven J. Murdoch and others showed that this banknote detection code does not rely on the EURion pattern.[6] It instead detects a digital watermark embedded in the images, developed by Digimarc.[7]

http://en.wikipedia.org/wiki/EURion_constellation#Counterfeit_Deterrence_System