  We present a longitudinal study of face recognition performance on Children
Longitudinal Face (CLF) dataset containing 3,682 face images of 919 subjects,
in the age group [2, 18] years. Each subject has at least four face images
acquired over a time span of up to six years. Face comparison scores are
obtained from (i) a state-of-the-art COTS matcher (COTS-A), (ii) an open-source
matcher (FaceNet), and (iii) a simple sum fusion of scores obtained from COTS-A
and FaceNet matchers. To improve the performance of the open-source FaceNet
matcher for child face recognition, we were able to fine-tune it on an
independent training set of 3,294 face images of 1,119 children in the age
group [3, 18] years. Multilevel statistical models are fit to genuine
comparison scores from the CLF dataset to determine the decrease in face
recognition accuracy over time. Additionally, we analyze both the verification
and open-set identification accuracies in order to evaluate state-of-the-art
face recognition technology for tracing and identifying children lost at a
young age as victims of child trafficking or abduction.
