Abstract—As a form of biometric authentication, we proposed writer verification based on finger-writing of a simple symbol on a smartphone screen. Because everyone writes the same one symbol, verification based on differences in handwriting shape cannot be expected. Therefore, it is desirable to extract features that are independent of handwriting shape. In this study, we investigate the relationship between finger contact area and finger pressure, which change when a finger is pressed against a smartphone screen. These are independent of handwriting shape. Specifically, time-series data of finger pressure and contact area is plotted on a two-dimensional graph, this relationship is approximated with a straight line, the slope and intercept are extracted from the straight line, and they are fused as a new two-dimensional finger softness feature. Via a comparison with two-dimensional features produced by fusing the finger pressure with the contact area, our results confirm that the proposed feature is superior to conventional features.

Keywords—biometrics, writer verification, simple symbol, finger-softness feature

Cite: Takumi Fukuda and Isao Nakanishi, "Finger-Softness Feature for Writer Verification Based on Finger-Writing of a Simple Symbol," International Journal of Signal Processing Systems, vol. 13, pp. 11-15, 2025. doi: 10.18178/ijsps.2025.13.11-15