Performance analysis of digital cameras versus chromatic white light (CWL) sensors for the localization of latent fingerprints in crime scenes

Abstract

In future applications of contactless acquisition techniques for latent fingerprints the automatic localization of potential fingerprint traces in crime scenes is required. Our goal is to study the application of a camera-based approach 1 comparing with the performance of chromatic white light (CWL) techniques 2 for the latent fingerprint localization in coarse and the resulting acquisition using detailed scans. Furthermore, we briefly evaluate the suitability of the camera-based acquisition for the detection of malicious fingerprint traces using an extended camera setup in comparison to Kiltz et al. 3 Our experimental setup includes a Canon EOS 550D 4 digital single-lens reflex (DSLR) camera and a FRT MicroProf200 5 surface measurement device with CWL600 2 sensor. We apply at least two fingerprints to each surface in our test set with 8 different either smooth, textured and structured surfaces to evaluate the detection performance of the two localization techniques using different pre-processing and feature extraction techniques. Printed fingerprint patterns as reproducible but potentially malicious traces 3 are additionally acquired and analyzed on foil and compact discs. Our results indicate positive tendency towards a fast localization using the camera-based technique. All fingerprints that are located using the CWL sensor are found using the camera. However,the disadvantage of the camera-based technique is that the size of the region of interest for the detailed scan for each potential latent fingerprint is usually slightly larger compared to the CWL-based localization. Furthermore, this technique does not acquire 3D data and the resulting images are distorted due to the necessary angle between the camera and the surface. When applying the camera-based approach, it is required to optimize the feature extraction and classification. Furthermore, the required acquisition time for each potential fingerprint needs to be estimated to determine the time-savings of the camera-based localization approach throughout the entire acquisition of traces. The analysis of camera images of printed fingerprint patterns shows positive tendencies, too. However, only small sections of the fingerprint are sharply acquirable within a single photo, large sections of the image are usually blurred due to the depth of field of the camera lens.

Emerging latent fingerprint technologies: a review

“…These sensors are used to localize marks on various nonporous substrates and to separate overlapped fingermarks. [10][11][12][13] These sensors can also be used to estimate the age of latent fingerprints left on a variety of surfaces. [14][15][16][17][18][19] Some authors used contactless CWL sensors for determining the age of a fingermark.…”