Noncontact Physiological Measurement Using a Camera: A Technical Review and Future Directions

Abstract

Using a camera as an optical sensor to monitor physiological parameters has garnered considerable research interest in biomedical engineering in recent decades. Researchers have explored the use of a camera for monitoring a variety of physiological waveforms, together with the vital signs carried by these waveforms. Most of the obtained waveforms are related to the human respiratory and cardiovascular systems, and in addition of being indicative of overall health, they can also detect early signs of certain diseases. While using a camera for noncontact physiological signal monitoring offers the advantages of low cost and operational ease, it also has the disadvantages such as vulnerability to motion and lack of burden-free calibration solutions in some use cases. This study presents an overview of the existing camera-based methods that have been reported in recent years. It introduces the physiological principles behind these methods, signal acquisition approaches, various types of acquired signals, data processing algorithms, and application scenarios of these methods. It also discusses the technological gaps between the camera-based methods and traditional medical techniques, which are mostly contact-based. Furthermore, we present the manner in which noncontact physiological signal monitoring use has been extended, particularly over the recent years, to more day-to-day aspects of individuals’ lives, so as to go beyond the more conventional use case scenarios. We also report on the development of novel approaches that facilitate easier measurement of less often monitored and recorded physiological signals. These have the potential of ushering a host of new medical and lifestyle applications. We hope this study can provide useful information to the researchers in the noncontact physiological signal measurement community.

Towards Continuous Camera-Based Respiration Monitoring in Infants

“…Motion artifacts are a major problem for both the current monitoring technologies, e.g., CI, and most of the non-contact solutions [ 17 , 18 ]. Motion robustness is, therefore, paramount when aiming at a continuous RR detection in infants.…”

Deep Learning Methods for Remote Heart Rate Measurement: A Review and Future Research Agenda

“…Photoplethysmography (PPG) is a common method for measuring HR. It utilizes a light source and photodetector to measure the volumetric changes of blood vessels under the skin [ 6 , 7 ]. As the light source illuminates the tissue, small variations in reflected or transmitted light intensity from blood flow are captured by the photodetector, yielding the so-called PPG signal [ 7 ].…”

Camera Measurement of Physiological Vital Signs

“…Across all terms I found over 350 papers published on camera physiological measurement on PubMed alone. 1 There exist other surveys of camera methods [33,94,100,130,144] and some complementary comparative studies [100,156].…”