Now there is a new and even more sophisticated technology that uses finger veins for static biometric authentication. The technology was first proposed by Kono et al. and has been patented by Hitachi Ltd. (NYSE: HIT, TSE: 65010).
The approach uses near-infrared light, which is transmitted through the finger. The infrared light irradiates the back of the hand and light passes through the finger. A camera located at the palm side of the hand captures the light (see figure 1). At near-infrared wavelengths, the haemoglobin has a lower absorbance than at visible wavelengths, but it is relatively high compared to other proteins in the tissue. As haemoglobin in the blood absorbs the infrared light, the patterns of veins in the palm side of the finger are captured as shadows. Therefore, transmitting near-infrared light through a finger is suitable for the acquisition of its vein pattern.
The matching can be attained by following the acquisition of the infrared image of the finger, the normalization of the image and the extraction of the finger vein patterns (see figure 2). There are two techniques currently discussed:
The first algorithm to verify the finger vein pattern is called ââ?¬Å?repeated line trackingââ?¬Â? and the second one is called ââ?¬Å?partial template method using the concept of the immune systemââ?¬Â?.
The solution using finger veins is contactless and therefore more hygienic and not affected by dryness or roughness. In Japan, finger vein recognition is preferred over fingerprint, since fingerprinting is associated with crime. The vendor of the technology is claiming a false acceptance rate of 0.0001%, which needs to be evaluated.
However, the disadvantage is that the technology cannot be miniaturized like fingerprint recognition (matching on card). Finger vein patterns may change in the course of a human lifetime. There seem to be difficulties with thicker fingers for the light penetrating the finger. Since the finger is not uniform, fluctuations in brightness occur. In particular there are no further studies on a larger group with greater genetic and age variation or on finger vein pattern of children over long time periods. Nevertheless, the technology is now used in the U.S. by the Shinkin Central Bank for access control purposes (only verification). In Japan finger vein recognition is widely used in the financial sector, which is one of the most successful market sectors actually for finger vein recognition.
Quelle: v.Graevenitz, Gerik (2007): Biometric authentication in relation to payment systems and ATMs - A new approach for biometric verification using finger veins and the start of the proliferation of biometric incorporated ATMs in DuD - Datenschutz und Datensicherheit, Vieweg Verlag, Vol 31, 2007)