Face Anti-Spoofing with Multi-Scale Information

Face anti-spoofing has encountered increasing demand as one of the key technologies for reliable and safe authentication with faces. Current face anti-spoofing methods generally take a single crop of face region as input for classification, i.e. exploiting information at only one scale. This single-scale scheme mainly focuses on facial characteristics but not utilize the surrounding information, causing poor generalization for different scenarios with varied means of attacks. Besides, it is tedious or highly empirical to determine an optimal scale of face crops. To overcome the limitations of single-scale methods, in this work we propose to integrate Multi-Scale information for better Face ANti-Spoofing (MS-FANS). Specifically, the proposed MS-FANS method takes multiple face crops at different scales as input followed by a convolutional neural network (CNN) for feature extraction. Then the features from different scales form as a sequence, which are fed into a Long Short-Term Memory (LSTM) network for adaptive fusion of multi-scale information, constructing the final representation for classification. Benefited from this multi-scale design, MS-FANS can adaptively utilize context information from multiple scales, leading to promising performance on two challenging face anti-spoofing datasets, Idiap REPLAY-ATTACK and CASIA-FASD, with significant improvement compared with the existing methods.