Optimal wavelength selection for noncontact reflection photoplethysmography

Corral-Martínez, Luis Francisco; Паез, Гонзало; Strojnik, Marija

doi:10.1117/12.903190

Cited by 28 publications

(6 citation statements)

References 12 publications

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“…35 ( ) 1913 optical filters in the camera, the skin-reflection, and the emission spectrum of the light source. We further considered predictions of the relative PPG-amplitude by Hülsbusch (2008) and measurements of the absolute amplitude by Corral et al (2011), and considered them in good agreement with our results.…”

Section: Discussionmentioning

confidence: 55%

“…In this spectrum, the absorption peaks of oxygenated blood at λ = 542 nm and λ = 577 nm can be clearly recognized. Corral et al (2011) measured σ (PPG (λ)) using a spectrometer analyzing the light reflected from a skin-region illuminated by a tungsten-halogen incandescent light source. Their measurement did not include the normalization, i.e.…”

Section: Analysis Of the Pulse-signal In Rgb-spacementioning

confidence: 99%

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Improved motion robustness of remote-PPG by using the blood volume pulse signature

2014

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Remote photoplethysmography (rPPG) enables contact-free monitoring of the blood volume pulse using a color camera. Essentially, it detects the minute optical absorption changes caused by blood volume variations in the skin. In this paper, we show that the different absorption spectra of arterial blood and bloodless skin cause the variations to occur along a very specific vector in a normalized RGB-space. The exact vector can be determined for a given light spectrum and for given transfer characteristics of the optical filters in the camera. We show that this 'signature' can be used to design an rPPG algorithm with a much better motion robustness than the recent methods based on blind source separation, and even better than the chrominance-based methods we published earlier. Using six videos recorded in a gym, with four subjects exercising on a range of fitness devices, we confirm the superior motion robustness of our newly proposed rPPG methods. A simple peak detector in the frequency domain returns the correct pulse-rate for 68% of total measurements compared to 60% for the best previous method, while the SNR of the pulse-signal improves from - 5 dB to - 4 dB. For a large population of 117 stationary subjects we prove that the accuracy is comparable to the best previous method, although the SNR of the pulse-signal drops from + 8.4 dB to + 7.6 dB. We expect the improved motion robustness to significantly widen the application scope of the rPPG-technique.

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Section: Discussionmentioning

confidence: 55%

Section: Analysis Of the Pulse-signal In Rgb-spacementioning

confidence: 99%

Improved motion robustness of remote-PPG by using the blood volume pulse signature

2014

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“…The pulsatility of the blood would still be available in this ratio provided that the pulsatility due to the blood volume changes is different in the individual color channels. Given the pulsatility as a function of wavelength exhibits a strong peak in green and the dips in red [9], [10], as illustrated in Fig. 1, the ratio of normalized green and red would make a motion robust pulse signal S i…”

Section: Discussionmentioning

confidence: 99%

Robust Pulse Rate From Chrominance-Based rPPG

Haan

Jeanne

2013

IEEE Trans. Biomed. Eng.

995

705

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Remote photoplethysmography (rPPG) enables contactless monitoring of the blood volume pulse using a regular camera. Recent research focused on improved motion robustness, but the proposed blind source separation techniques (BSS) in RGB color space show limited success. We present an analysis of the motion problem, from which far superior chrominance-based methods emerge. For a population of 117 stationary subjects, we show our methods to perform in 92% good agreement ( ±1.96σ) with contact PPG, with RMSE and standard deviation both a factor of 2 better than BSS-based methods. In a fitness setting using a simple spectral peak detector, the obtained pulse-rate for modest motion (bike) improves from 79% to 98% correct, and for vigorous motion (stepping) from less than 11% to more than 48% correct. We expect the greatly improved robustness to considerably widen the application scope of the technology.

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“…The relative , AC/DC, PPG amplitude as function of the wavelength λ has been modeled by Hülsbusch38. Corral39 measured the absolute , i.e. AC, PPG spectrum using a tungsten-halogen lamp as illumination, which emits radiation in both the visible and NIR section of the light spectrum.…”

Section: Methodsmentioning

confidence: 99%

New principle for measuring arterial blood oxygenation, enabling motion-robust remote monitoring

Gastel

Stuijk

Haan

2016

Sci Rep

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Finger-oximeters are ubiquitously used for patient monitoring in hospitals worldwide. Recently, remote measurement of arterial blood oxygenation (SpO2) with a camera has been demonstrated. Both contact and remote measurements, however, require the subject to remain static for accurate SpO2 values. This is due to the use of the common ratio-of-ratios measurement principle that measures the relative pulsatility at different wavelengths. Since the amplitudes are small, they are easily corrupted by motion-induced variations. We introduce a new principle that allows accurate remote measurements even during significant subject motion. We demonstrate the main advantage of the principle, i.e. that the optimal signature remains the same even when the SNR of the PPG signal drops significantly due to motion or limited measurement area. The evaluation uses recordings with breath-holding events, which induce hypoxemia in healthy moving subjects. The events lead to clinically relevant SpO2 levels in the range 80–100%. The new principle is shown to greatly outperform current remote ratio-of-ratios based methods. The mean-absolute SpO2-error (MAE) is about 2 percentage-points during head movements, where the benchmark method shows a MAE of 24 percentage-points. Consequently, we claim ours to be the first method to reliably measure SpO2 remotely during significant subject motion.

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Optimal wavelength selection for noncontact reflection photoplethysmography

Cited by 28 publications

References 12 publications

Improved motion robustness of remote-PPG by using the blood volume pulse signature

Improved motion robustness of remote-PPG by using the blood volume pulse signature

Robust Pulse Rate From Chrominance-Based rPPG

New principle for measuring arterial blood oxygenation, enabling motion-robust remote monitoring

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