Pore Sub‐Features Reproducibility in Direct Microscopic and Livescan Images—Their Reliability in Personal Identification

Abstract: Third level features have been reported to have equal discriminatory power as second level details in establishing personal identification. Pore area, as an extended set third level sub‐feature, has been studied by minimizing possible factors that could affect pore size. The reproducibility of pore surface area has been studied using direct microscopic and 500 ppi Livescan images. Direct microscopic pore area measurements indicated that the day on which the pore area was measured had a significant impact on the measured pore area. Pore area measurement was shown to be difficult to estimate in 500 ppi Livescan measurements owing to lack of resolution. It is not possible to reliably use pore area as an identifying feature in fingerprint examination.     

Integration of Pore Features into the Evaluation of Fingerprint Evidence*

Fingerprint practitioners rely on level 3 features to make decisions in relation to the source of an unknown friction ridge skin impression. This research proposes to assess the strength of evidence associated with pores when shown in (dis)agreement between a mark and a reference print. Based upon an algorithm designed to automatically detect pores, a metric is defined in order to compare different impressions. From this metric, the weight of the findings is quantified using a likelihood ratio. The results obtained on four configurations and 54 donors show the significant contribution of the pore features and translate into statistical terms what latent fingerprint examiners have developed holistically through experience. The system provides LRs that are indicative of the true state under both the prosecution and the defense propositions. Not only such a system brings transparency regarding the weight to assign to such features, but also forces a discussion in relation to the risks of such a model to mislead.     

对暗视场显现指印汗孔细节特征的初步研究

在指印鉴定工作中,利用汗孔细节特征对指印进行同一认定在国外司法鉴定领域已有应用,但在实际案件中,由于汗孔细节特征的发现和提取较为困难,同时对汗孔的分类、命名、标示等又存在一些没有解决的问题,目前在我国刑事技术领域还没有得到应用。文章采用一种常用的配光方法———暗视场照明方法,显现光滑平面玻璃上汗潜指印的汗孔细节特征,并对实验中影响汗孔细节特征形成的部分因素进行了初步研究。     

Study of poroscopy among South Indian population

Poroscopy is the term applied to a specialized study of pore structure found on papillary ridges of skin as a means of identification. It comes under level 3 detail of identification and hence is more reliable and accurate. The goal of this study is to estimate the importance of poroscopy for identification of individuals and to determine the gender based on frequency, type, and shape of pores. Left plain thumb prints of 200 individuals (100 men and 100 women) aged between 18 and 60 belonging to South Indian population were observed. The results have shown that women tend to have a significantly higher frequency of pores than men. Number of pores ≤ 8 pores/25 mm(2) is more likely to be of male origin and ≥9 pores/25 mm(2) is more likely to be of female origin. There was no significant sex difference based on type and shape of pores.