Table 2. Comparison of the algorithmic steps of SB and the proposed SB-CWT.
SB (Wang et al., 2017c) | SB-CWT | |
---|---|---|
Signal decomposition | FFT | CWT using generalized Morse wavelet |
rPPG signal extraction | POS (Wang et al., 2017a) + alpha tuning (De Haan & Jeanne, 2013) | POS (Wang et al., 2017a) + alpha tuning (De Haan & Jeanne, 2013) |
Weighting function | Ratio between the pulsatile amplitude and intensity variation amplitude | Scale-dependent energy distribution |
Signal transformation back into the time domain | IFFT | ICWT |
Note:
CWT, continuous wavelet transform; FFT, fast Fourier transform; ICWT, inverse continuous wavelet transform; IFFT, inverse fast Fourier transform; POS, Plane-Orthogonal-to-Skin; rPPG, remote photoplethysmography.