Reducing the effects of parallax in camera-based pulse-oximetry

Research output: Contribution to journalArticleAcademicpeer-review

Abstract

Camera-based pulse-oximetry enables contactless estimation of peripheral oxygen saturation (SpO2). Because of the lack of readily available and affordable single-optics multispectral cameras, custom-made multi-camera setups with different optical filters are currently mostly used. The introduced parallax by these cameras could however jeopardise the SpO2 algorithm assumptions, especially during subject movement. In this paper we investigate the effect of parallax quantitatively by creating a large dataset consisting of 150 videos with three different parallax settings and with realistic and challenging motion scenarios. We estimate oxygen saturation values with a previously used global frame registration method and with a newly proposed adaptive local registration method to further reduce the parallax-induced image misalignment. We found that the amount of parallax has an important effect on the accuracy of the SpO2 measurement during movement and that the proposed local image registration reduces the error by more than a factor of 2 for the most common motion scenarios during screening. Extrapolation of the results suggests that the error during the most challenging motion scenario can be reduced to approximately 2 percent when using a parallax-free single-optics camera. This study provides important insights on the possible applications and use cases of remote pulse-oximetry with current affordable and readily available cameras.

Original languageEnglish
Article number419199
Pages (from-to)2813-2824
Number of pages12
JournalBiomedical Optics Express
Volume12
Issue number5
DOIs
Publication statusPublished - 1 May 2021

Keywords

  • contactless monitoring
  • remote pulse-oximetry
  • remote photoplethysmography
  • camera
  • vital signs monitoring

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