  Automatic border control systems are wide spread in modern airports
worldwide. Morphing attacks on face biometrics is a serious threat that
undermines the security and reliability of face recognition systems deployed in
airports and border controls. Therefore, developing a robust Machine Learning
(ML) system is necessary to prevent criminals crossing borders with fake
identifications especially since it has been shown that security officers
cannot detect morphs better than machines. In this study, we investigate the
generalization power of Convolutional Neural Network (CNN) architectures
against morphing attacks. The investigation utilizes 5 distinct CNNs namely
ShuffleNet, DenseNet201, VGG16, EffecientNet-B0 and InceptionResNet-v2. Each
CNN architecture represents a well-known family of CNN models in terms of
number of parameters, architectural design and performance across various
computer vision applications. To ensure robust evaluation, we employ 4
different datasets (Utrecht, London, Defacto and KurdFace) that contain a
diverse range of digital face images which cover variations in ethnicity,
gender, age, lighting condition and camera setting. One of the fundamental
concepts of ML system design is the ability to generalize effectively to
previously unseen data, hence not only we evaluate the performance of CNN
models within individual datasets but also explore their performance across
combined datasets and investigating each dataset in testing phase only.
Experimental results on more than 8 thousand images (genuine and morph) from
the 4 datasets show that InceptionResNet-v2 generalizes better to unseen data
and outperforms the other 4 CNN models.
