Real-time outdoor concealed-object detection with passive millimeter wave imaging

• Published in: Optics express Vol. 19; no. 3; p. 2530
• Main Authors: Yeom, Seokwon, Lee, Dong-Su, Son, Jung-Young, Jung, Min-Kyoo, Jang, YuShin, Jung, Sang-Won, Lee, Seok-Jae
• Format: Journal Article
• Language: English
• Published: United States 31.01.2011
• Subjects: Computer Systems; Environmental Monitoring - instrumentation; Equipment Design; Equipment Failure Analysis; Image Enhancement - instrumentation; Image Interpretation, Computer-Assisted - instrumentation; Microwaves
• ISSN: 1094-4087; 1094-4087
• DOI: 10.1364/OE.19.002530

Millimeter wave imaging is finding rapid adoption in security applications such as the detection of objects concealed under clothing. A passive imaging system can be realized as a stand-off type sensor that can operate in open spaces, both indoors and outdoors. In this paper, we address real-time outdoor concealed-object detection and segmentation with a radiometric imaging system operating in the W-band. The imaging system is equipped with a dielectric lens and a receiver array operating at around 94 GHz. Images are analyzed by multilevel segmentation to identify a concealed object. Each level of segmentation comprises vector quantization, expectation-maximization, and Bayesian decision making to cluster pixels on the basis of a Gaussian mixture model. In addition, we describe a faster process that adopts only vector quantization for the first level segmentation. Experiments confirm that the proposed methods provide fast and reliable detection and segmentation for a moving human subject carrying a concealed gun.