Detection and recognition of concealed faces using a 340 GHz imaging system

Abstract

Biometric recognition and surveillance systems based on visible band imaging cameras encounter a number of limitations such as the effects of lighting conditions and occlusions. As a result, there is an interest in beyond the visible spectrum in this field. Due to their characteristics such as transmission through common barrier materials, use of millimeter and submillimeter wave systems in the field of biometrics have been proposed in order to overcome these difficulties. This paper discusses the possibility of biometric identification of individuals using face images acquired by an active terahertz imaging system operating at 340 GHz. Optical resolution at this frequency is sufficient to provide detailed face images containing characteristic features of individual people. With the ability to penetrate through clothing materials, these characteristics are expected to be preserved in concealed face images, which would allow recognition of individuals through clothing items worn around the face. Here, we examine the effect of the concealment on THz images by comparing face images acquired with and without concealment, in terms of a future face recognition system operating at this frequency.