Fingerprints have long been recognized as a unique and reliable means of personal identification. Central to the analysis and enhancement of fingerprints is the concept of the fingerprint core. Although the location of the core is used in many applications, to the best of our knowledge, this study is the first to investigate the empirical distribution of the core over a large, combined dataset of rolled, as well as plain fingerprint recordings. We identify and investigate the extent of incomplete rolling during the rolled fingerprint acquisition and investigate the centrality of the core. After correcting for the incomplete rolling, we find that the core deviates from the fingerprint center by 5.7% $\pm$ 5.2% to 7.6% $\pm$ 6.9%, depending on the finger. Additionally, we find that the assumption of normal distribution of the core position of plain fingerprint recordings cannot be rejected, but for rolled ones it can. Therefore, we use a multi-step process to find the distribution of the rolled fingerprint recordings. The process consists of an Anderson-Darling normality test, the Bayesian Information Criterion to reduce the number of possible candidate distributions and finally a Generalized Monte Carlo goodness-of-fit procedure to find the best fitting distribution. We find the non-central Fischer distribution best describes the cores' horizontal positions. Finally, we investigate the correlation between mean core position offset and the NFIQ 2 score and find that the NFIQ 2 prefers rolled fingerprint recordings where the core sits slightly below the fingerprint center.

翻译：指纹长期以来一直被认为是一种独特且可靠的个人识别手段。指纹核心的概念在指纹分析与增强中占据核心地位。尽管核心位置被用于众多应用，但据我们所知，本研究首次在大规模混合数据集（包含滚动和平按指纹记录）上探究了核心的经验分布。我们识别并研究了滚动指纹采集过程中不完全滚动现象的范围，并考察了核心的中心性。在纠正不完全滚动后，我们发现核心偏离指纹中心的程度因手指不同而异，偏差范围为 5.7% ± 5.2% 至 7.6% ± 6.9%。此外，我们发现平按指纹记录核心位置的正态分布假设不能被拒绝，但滚动指纹记录的核心位置却可以被拒绝。因此，我们采用多步骤过程来确定滚动指纹记录的分布。该过程包括Anderson-Darling正态性检验、使用贝叶斯信息准则减少候选分布数量，以及最终采用广义蒙特卡洛拟合优度程序来寻找最佳拟合分布。我们发现非中心Fischer分布最能描述核心的水平位置。最后，我们考察了核心平均位置偏移与NFIQ 2分数之间的相关性，并发现NFIQ 2更倾向于核心略低于指纹中心的滚动指纹记录。