Explainer: Vascular Pattern Recognition
Vascular pattern recognition, also commonly referred to as vein pattern authentication, uses near-infrared light to reflect or transmit images of blood vessels. Researchers have determined that the vascular pattern of the human body is unique to a specific individual and does not change as people age.
Potential for the use of the technology can be traced to a research paper prepared in 1992 by Dr. K. Shimizu, in which he discussed optical trans-body imaging and potential optical CT scanning applications. The first paper about the use of vascular patterns for biometric recognition was published in 2000. That paper described technology that used subcutaneous blood vessels in the back of the hand that was the first to become a commercially available vascular pattern recognition system. Additional research improved that technology and inspired additional research and commercialization of finger- and palm-based systems.
Typically, the technology either identifies vascular patterns in the bank of hands or fingers. To identify patters in hands, near-infrared rays generated from a bank of light emitting diodes (LEDs) penetrate the skin of the back of the hand. Due to the difference in absorbance of blood vessels and other tissues, the reflected near-infrared rays produce an image processing techniques producing an extracted vascular pattern. From the extracted vascular pattern, various feature rich data such as vessel branching points, vessel thickness and branching angels are extracted and stored as a template.
In vascular pattern in fingers, near-infrared rays generated from a bank of LEDs penetrate the finger or hand and are absorbed by the hemoglobin the blood. The areas in which the rays are absorbed (i.e., veins) appear as dark areas similar to a shadow in an image taken by a charge-construct device camera. Image processing can then construct a vein pattern from the captured image. Next this pattern is digitized and compressed so that it can be registered as a template.
Both technologies are touted since the technology is difficult to forge, is contact-less, has many, varied and users and is capable of one to one and one to many matching. Vascular patterns are difficult to recreate because they are inside the hand and, for some approaches, blood needs to flow to register an image. Users do not touch the sensing surface, which address hygiene concerns and improves user acceptance. Then technology has been deployed in ATMs, hospital and universities in Japan. Applications include ID verification, high security physical access control, high security data access and point-of-sale access control. The technology is also highly respected due to its dual matching capacity, as users vascular patterns can be matched against personalized ID cards and smart cards or against a database of many scanned vascular patterns.