Banknote Authentication with Mobile Devices

Maintaining confidence in security documents, especially banknotes, is and remains a major concern for the central banks in order to maintain the stability of the economy around the world. In this paper we describe an image processing and pattern recognition approach which is based on the Sound-of-Intaglio principle for the usage in smart devices such as smartphones. Today, in many world regions smartphones are in use. These devices become more and more computing units, equipped with resource-limited, but effective CPUs, cameras with illumination, and flexible operating systems. Hence, it is obvious to apply smartphones for banknote authentication, especially for visually impaired persons. Our approach shows that those devices are capable of processing data under the constraints of image quality and processing power. Strictly a mobile device as such is not an industrial product for harsh environments, but it is possible to use mobile devices for banknote authentication. The concept is based on a new strategy for constructing adaptive Wavelets for the analysis of different print patterns on a banknote. Furthermore, a banknote specific feature vector is generated which describes an authentic banknote effectively under various illumination conditions. A multi-stage Linear-discriminant-analysis classifier generates stable and reliable output.