A Multi-Channel Ratio-of-Ratios Method for Noncontact Hand Video Based SpO[Formula Omitted] Monitoring Using Smartphone Cameras

Blood oxygen saturation (SpO[Formula Omitted]) is an important indicator forpulmonary and respiratory functionalities. Clinical findings on COVID-19 show that many patients had dangerously low blood oxygen levels not long before conditions worsened. It is therefore recommended, especially for the vu...

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Bibliographic Details
Published in:IEEE journal of selected topics in signal processing 2022-02, Vol.16 (2), p.197
Main Authors: Tian, Xin, Chau-Wai Wong, Ranadive, Sushant M, Wu, Min
Format: Article
Language:English
Subjects:
Bandpass filters
Blood
Broadband
Cameras
Channels
Color
COVID-19
Heart rate
Irritation
Light
Light sources
Monitoring
Oxygen
Oxygen content
Smartphones
Telemedicine
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Summary:Blood oxygen saturation (SpO[Formula Omitted]) is an important indicator forpulmonary and respiratory functionalities. Clinical findings on COVID-19 show that many patients had dangerously low blood oxygen levels not long before conditions worsened. It is therefore recommended, especially for the vulnerable population, to regularly monitor the blood oxygen level for precaution. Recent works have investigated how ubiquitous smartphone cameras can be used to infer SpO[Formula Omitted]. Most of these works are contact-based, requiring users to cover a phone’s camera and its nearby light source with a finger to capture reemitted light from the illuminated tissue. Contact-based methods may lead to skin irritation and sanitary concerns, especially during a pandemic. In this paper, we propose a noncontact method for SpO[Formula Omitted] monitoring using hand videos acquired by smartphones. Considering the optical broadband nature of the red (R), green (G), and blue (B) color channels of the smartphone cameras, we exploit all three channels of RGB sensing to distill the SpO[Formula Omitted] information beyond the traditional ratio-of-ratios (RoR) method that uses only two wavelengths. To further facilitate an accurate SpO[Formula Omitted] prediction, we design adaptive narrow bandpass filters based on accurately estimated heart rate to obtain the most cardiac-related AC component for each color channel. Experimental results show that our proposed blood oxygen estimation method can reach a mean absolute error of 1.26% when a pulse oximeter is used as a reference, outperforming the traditional RoR method by 25%.
ISSN:1932-4553
1941-0484
DOI:10.1109/JSTSP.2022.3152352