Thermistor at a distance: unobtrusive measurement of breathing.

This paper unveils a thermal imaging methodology to recover the breathing waveform from the subject's nostrils. The resulting functionality is equivalent to that of a thermistor, but it is materialized in a contact-free manner. First, the nostril region is segmented and tracked over time through a network of cooperating probabilistic trackers. The mean thermal signal of the nostril region carries the breathing information. This information is extracted through wavelet analysis. The method has been tested on 20 healthy individuals. The breathing waveforms determined via the imaging computation were compared with the corresponding ones extracted from thermistors. The high degree of agreement between the two measurement methods confirms the validity of the proposed approach and opens the way for clinical applications. Furthermore, thermal imaging can be potentially used as an investigative tool to understand breathing physiology in ways not possible with contact sensors.