Hitachi Ltd developed a technology for finger vein authentication using a smartphone camera.
According to the company, it is the first practical finger vein authentication technology that uses a smartphone camera.
There were two major challenges in the development of a finger vein authentication technology using a smartphone camera. First, a vein pattern needs to be stably extracted from a reflection image using visible light. Second, it is necessary to accurately detect the positions of multiple fingers in front of the camera for high-accuracy authentication.
To solve the first challenge, Hitachi developed a method to extract a vein pattern by using color information. To deal with the second challenge, the company developed a technology to extract fingers from a background image and an advanced authentication technology that uses multiple fingers.
For the extraction of a finger vein pattern, Hitachi exploited the fact that a smartphone camera can take color pictures while the conventional infrared method can produce only monochrome images. For example, areas where there are veins are less reddish and more bluish than other areas. And finger winkles are more reddish and darker than the areas surrounding them.
For the authentication using multiple fingers, the colors and shapes of fingers are learned in advance, and the image of fingers is separated from the background image. Also, the postures of fingers are normalized so that authentication can be performed even when the angle of the hand slightly changes.
Furthermore, while only one finger is used for the infrared method, multiple fingers are used this time to improve authentication accuracy. For example, when two of the four fingers match the registered ones, the authentication is passed.