Optimal color channel combination across skin tones for remote heart rate measurement in camera-based photoplethysmography
Research output: Contribution to journal › Research article › Contributed › peer-review
Contributors
Abstract
Objective: The heart rate is an essential vital sign that can be measured remotely with camera-based photoplethysmography (cbPPG). Systems for cbPPG typically use cameras that deliver red, green, and blue (RGB) channels. The combination of these channels has been proven to increase signal-to-noise ratio (SNR) and heart rate measurement accuracy (ACC). However, many combinations remain untested, the comparison of proposed combinations on large datasets is insufficiently investigated, and the interplay with skin tone is rarely addressed. Methods: Eight regions of interest and eight color spaces with a total of 25 color channels were compared in terms of ACC and SNR based on the Binghamton-Pittsburgh-RPI Multimodal Spontaneous Emotion Database (BP4D+). Additionally, two systematic grid searches were performed to evaluate ACC in the space of linear combinations of the RGB channels. Results: Glabella and forehead regions of interest provided highest ACC (up to 74.1 %) and SNR (> -3 dB) with the hue channel H from HSV color space and the chrominance channel Q from NTSC color space. The grid searches revealed a global optimum of linear RGB combinations (ACC: 79.2 %). This optimum occurred for all skin tones, although ACC dropped for darker skin tones. Conclusion: Through systematic grid searches we were able to identify the skin tone independent optimal linear RGB color combination for measuring heart rate with cbPPG. Our results proved on a large dataset that the identified optimum outperformed conventionally used color channels. Significance: The presented findings provide useful evidence for future considerations of algorithmic approaches for cbPPG.
Details
Original language | English |
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Article number | 102644 |
Journal | Biomedical signal processing and control |
Issue number | 68 |
Publication status | Published - Jul 2021 |
Peer-reviewed | Yes |
External IDs
ORCID | /0000-0001-6754-5257/work/142232813 |
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ORCID | /0000-0003-4012-0608/work/142235695 |
Keywords
Research priority areas of TU Dresden
Sustainable Development Goals
ASJC Scopus subject areas
Keywords
- Color channel combination, Color space transformation, Heart rate, Imaging photoplethysmography, Region of interest