EURion constellation
The EURion constellation, named after the developer Omron Omron rings also is a pattern on banknotes. Since the basis of this pattern images can be detected algorithmically banknotes, it is technically possible to produce copiers and printers that can prevent copying for purposes of forgery. The algorithms actually used by hardware and software have been kept by the developers but deliberately kept secret.
The name EURion constellation was coined by Markus Kuhn, a computer scientist at the University of Cambridge, who discovered this pattern. The word is a portmanteau of EURion EUR ( the currency code for the Euro ) and the name of the constellation Orion, the pattern resembles away.
Markus Kuhn experimented in 2002 with a copier from Xerox, which refused to copy certain banknotes. The EURion constellation was described by Kuhn as a pattern of five small green, yellow or orange circles. This repeat within the bill at various places.
Later, Andrew Steer examined these patterns further. He discovered a simple integer ratios between the squared distances of the rings to each other, which is an indication of how the pattern of image processing software can be efficiently recognized.
However, the EURion constellation is not the only feature that allows copying software detects an attempt to copy notes to scan or edit images of banknotes. The pattern is used primarily by color copiers; in image editing programs such as Photoshop, however it does not seem to serve for the detection of banknote images.
Affected banknotes
One of the first bills that had this safety feature was most likely the 10 - guilder banknote of the Netherlands, followed by the 100 - and 200 - DM notes ( BBk IIIa), which were given from 1 October 1997 in circulation.
Banknote recognition by software and hardware
Various scanners, color copiers and image editing programs such as Adobe Photoshop newer than version 7 or Corel Paint Shop Pro refuse to process banknotes. In a Wired magazine article, the Counterfeit Deterrence System (CDS ) used for this purpose has been described. Developed by the Central Bank Counterfeit Deterrence has Group. The inclusion of this as a binary module in CDS products is done according to the organization on a voluntary basis.
To prevent counterfeiters circumvent the protection, the algorithms used for the detection of notes were not published, but only passed on in the form of recognition software for developers of electronic reproduction devices that incorporate the software into their devices.
Experiments by Steven J. Murdoch and other have shown that the detection of the bills does not depend solely on EURion pattern. Other features will be taken into account, which are not yet known to the public so far. One of them seems to be a digital watermark by Digimarc.
Open source software such as GIMP and scanner drivers have no such restrictions and can still be used for the digitization and processing of banknotes and other "protected" documents. In this respect, the protection concept is only partially effective.