Reduced contact lifting of latent fingerprints from curved surfaces

Fingerprint is the most well-known and successfully deployed biometric modalities in view of its ease of acquisition, established use, acceptance and high recognition rate (i.e., robustness). This is also due in part to its use in crime scene investigations to link crimes to suspected individuals. One form of fingerprint is called the latent fingerprint. Despite its subtle appearance, the latent fingerprint is commonly left all over the place unintentionally, including on water taps, door knobs, elevator buttons, and cups. To lift these latent fingerprints, the conventional approach involving the process of powdering and taping may physically damage the latent fingerprint. Therefore, a reduced contact method is desirable. This paper focuses on latent fingerprints left on curved surfaces, such as water taps, door knobs, and water flasks. The latent fingerprint is uncovered (i.e., made visible) by means of fuming, and the end product is captured by a camera. A geometrical compensation method, which takes the curvature of the surface into consideration, is formulated to geometrically correct (i.e., flatten) the image. The corrected image is further enhanced and sent for matching purposes. Experiments show that the application of the proposed geometrical compensation method is able to flatten the fingerprint image uncovered from a single directional curved surface and improve its matching score.