Privacy Protected Contactless Cardio-respiratory Monitoring using Defocused Cameras during Sleep

Fuente: arXiv
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Main Authors: Zhu, Yingen, Huang, Jia, Lu, Hongzhou, Wang, Wenjin
Format: Preprint
Published: 2024
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author Zhu, Yingen
Huang, Jia
Lu, Hongzhou
Wang, Wenjin
author_facet Zhu, Yingen
Huang, Jia
Lu, Hongzhou
Wang, Wenjin
contents The monitoring of vital signs such as heart rate (HR) and respiratory rate (RR) during sleep is important for the assessment of sleep quality and detection of sleep disorders. Camera-based HR and RR monitoring gained popularity in sleep monitoring in recent years. However, they are all facing with serious privacy issues when using a video camera in the sleeping scenario. In this paper, we propose to use the defocused camera to measure vital signs from optically blurred images, which can fundamentally eliminate the privacy invasion as face is difficult to be identified in obtained blurry images. A spatial-redundant framework involving living-skin detection is used to extract HR and RR from the defocused camera in NIR, and a motion metric is designed to exclude outliers caused by body motions. In the benchmark, the overall Mean Absolute Error (MAE) for HR measurement is 4.4 bpm, for RR measurement is 5.9 bpm. Both have quality drops as compared to the measurement using a focused camera, but the degradation in HR is much less, i.e. HR measurement has strong correlation with the reference ($R \geq 0.90$). Preliminary experiments suggest that it is feasible to use a defocused camera for cardio-respiratory monitoring while protecting the privacy. Further improvement is needed for robust RR measurement, such as by PPG-modulation based RR extraction.
format Preprint
id arxiv_https___arxiv_org_abs_2401_08935
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Privacy Protected Contactless Cardio-respiratory Monitoring using Defocused Cameras during Sleep
Zhu, Yingen
Huang, Jia
Lu, Hongzhou
Wang, Wenjin
Signal Processing
The monitoring of vital signs such as heart rate (HR) and respiratory rate (RR) during sleep is important for the assessment of sleep quality and detection of sleep disorders. Camera-based HR and RR monitoring gained popularity in sleep monitoring in recent years. However, they are all facing with serious privacy issues when using a video camera in the sleeping scenario. In this paper, we propose to use the defocused camera to measure vital signs from optically blurred images, which can fundamentally eliminate the privacy invasion as face is difficult to be identified in obtained blurry images. A spatial-redundant framework involving living-skin detection is used to extract HR and RR from the defocused camera in NIR, and a motion metric is designed to exclude outliers caused by body motions. In the benchmark, the overall Mean Absolute Error (MAE) for HR measurement is 4.4 bpm, for RR measurement is 5.9 bpm. Both have quality drops as compared to the measurement using a focused camera, but the degradation in HR is much less, i.e. HR measurement has strong correlation with the reference ($R \geq 0.90$). Preliminary experiments suggest that it is feasible to use a defocused camera for cardio-respiratory monitoring while protecting the privacy. Further improvement is needed for robust RR measurement, such as by PPG-modulation based RR extraction.
title Privacy Protected Contactless Cardio-respiratory Monitoring using Defocused Cameras during Sleep
topic Signal Processing
url https://arxiv.org/abs/2401.08935