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.