Supporting fingerprint identification assessments using a skin stretch model - A preliminary study

- Limits to the distortion caused by skin stretch have been modelled.
- The model has been tested on 5 donors using 10 minutiae.
- A within-source comparison was determined and compared to between-source comparisons.
- Proposed tool for the assessment of fingerprint expert opinion in casework.

To support fingerprint expert opinion, this research proposes an approach that combines subjective human analysis (as currently applied by fingerprint practitioners) with a statistical test of the result. This approach relies on the hypothesis that there are limits to the distortion caused by skin stretch. Such limits can be modelled by applying a multivariate normal probability density function to the distances and angle formed by a marked ridge characteristic and the two closest neighbouring minutiae.This study presents a model tested on 5 donors in total. The “expected range” of distortion in a within-source comparison using 10 minutiae was determined and compared to between-source comparisons. The expected range of log probability densities for within-source comparisons marked with 10 minutiae was determined to be from −33.4 to −60.0, with all between-source data falling outside this range, between −83 and −305.These results suggest that the proposed generated metric could be a powerful tool for the assessment of fingerprint expert opinion in operational casework.