Signatures of live fingers extracted from a series of fingerprint images

Abstract

Life recognition is desired for unattended fingerprint identification. We look at the color changes in a series of fingerprint images acquired during the course of an input action. As we press a finger upon an input device, a fingerprint area gradually increases and its color changes. This is due to the blood movements induced by a finger deformation. For example, we can declare a finger is alive if its color change exceeds a certain value. However, the color changes in the images acquired by a conventional device using a prism are very small. This is because the light reflected by the valley regions of a finger carries little information about the blood movements. We tried a fingerprint sensor based on scattered light detection. Here, a plastic plate serves as a light-guide for LEDs mounted on its edge. When a finger is pressed against the plate, the propagating light is scattered by the finger and leaks out of the plate. A standard color CCD camera placed near the plate captures the scattered light. Data extracted from more than ten people of different age groups indicate that there is a certain minimum value for the color changes.

Dual-LED imaging system for secure fingerprint identification

“…On the other hand, the replica shows smaller hysteresis. It is interesting to note that this dual-LED light source results in hysteresis in both of the x and y trajectories, while the quasi-white LED generates hysterisis only in the x trajectory 4 . Another point to be addressed here is the reproducibility of these results.…”

“…In our previous studies 4,9,10 , we have proposed various indices for life recognition which examine the correlation between the area signal and the color signals. Here, we propose indices solely based on the color signals.…”

“…Countermeasures against such frauds are proposed and these involve detecting life-related signals such as pulse, heat, electronic resistance from a fingertip. For example, pulse can be detected by a simple configuration that includes a light source and a detector 4 . A light source such as an LED illuminates a finger and the light scattered by the finger tissue leaks out.…”

Life recognition based on color variations in fingerprint images of live and artificial fingers

“…Here, the area signal is divided by A max to cope with the individual differences of a finger size. Next, we propose another view for the life recognition indices based on the resistance model in an electric circuit 4 . The voltage is analogous to the force applied to a finger and the current is analogous to the blood flow.…”

“…Conventional technologies for rejecting replicas are proposed to detect life-related features such as the pulse (heartbeat), temperature, conductivity from a finger-tip. For example, pulses can be detected by a simple configuration which consists of compact, low-cost electronic components 4 . However, following problems may arise if pulses are to be used as a countermeasure against replicas.…”