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Proceedings Paper

Illumination-compensated non-contact imaging photoplethysmography via dual-mode temporally coded illumination
Author(s): Robert Amelard; Christian Scharfenberger; Alexander Wong; David A. Clausi
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Paper Abstract

Non-contact camera-based imaging photoplethysmography (iPPG) is useful for measuring heart rate in conditions where contact devices are problematic due to issues such as mobility, comfort, and sanitation. Existing iPPG methods analyse the light-tissue interaction of either active or passive (ambient) illumination. Many active iPPG methods assume the incident ambient light is negligible to the active illumination, resulting in high power requirements, while many passive iPPG methods assume near-constant ambient conditions. These assumptions can only be achieved in environments with controlled illumination and thus constrain the use of such devices. To increase the number of possible applications of iPPG devices, we propose a dual-mode active iPPG system that is robust to changes in ambient illumination variations. Our system uses a temporally-coded illumination sequence that is synchronized with the camera to measure both active and ambient illumination interaction for determining heart rate. By subtracting the ambient contribution, the remaining illumination data can be attributed to the controlled illuminant. Our device comprises a camera and an LED illuminant controlled by a microcontroller. The microcontroller drives the temporal code via synchronizing the frame captures and illumination time at the hardware level. By simulating changes in ambient light conditions, experimental results show our device is able to assess heart rate accurately in challenging lighting conditions. By varying the temporal code, we demonstrate the trade-off between camera frame rate and ambient light compensation for optimal blood pulse detection.

Paper Details

Date Published: 5 March 2015
PDF: 5 pages
Proc. SPIE 9316, Multimodal Biomedical Imaging X, 931607 (5 March 2015); doi: 10.1117/12.2078197
Show Author Affiliations
Robert Amelard, Univ. of Waterloo (Canada)
Christian Scharfenberger, Univ. of Waterloo (Canada)
Alexander Wong, Univ. of Waterloo (Canada)
David A. Clausi, Univ. of Waterloo (Canada)

Published in SPIE Proceedings Vol. 9316:
Multimodal Biomedical Imaging X
Fred S. Azar; Xavier Intes, Editor(s)

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