Algorithms 1 Computation details of HR extraction
Input: single colour signal $S=s_i\left(i=1,2,\dots N\right)$; sampling rate r; window size w; window function wf; overlap window size wn (here wn=3*w/4); minimum frequency f1 and maximum frequency f2.
Output: Estimated heart rate hr
1:	$\min \_\mathrm{hr}\_\mathrm{freq}=1+\mathrm{f}1*\mathrm{w}/\mathrm{r}$
2:	$\max \_\mathrm{hr}\_\mathrm{freq}=1+f2*w/r$
3:	For i in [1, 2, …, K, K= ⌊N/(w-wn) ⌋ ] do
4:	${\mathrm{win}}_{\mathrm{i}}=(\mathrm{i}-1)*(\mathrm{w}-\mathrm{wn})+1$
5:	end for
6:	For k in [1,2,…K] do
7:	${\mathrm{fwin}}_{\mathrm{k}}{=(\mathrm{s}}_{\mathrm{p}}{:\mathrm{s}}_{\mathrm{q}})*\mathrm{wf},$${\mathrm{where}\mathrm{p}=\mathrm{win}}_{\mathrm{i}}{\mathrm{and}\mathrm{q}=\mathrm{win}}_{\mathrm{i}}+\left(\mathrm{w}-\mathrm{wn}\right)-1$
8:	${\mathrm{A}}_{\mathrm{k}}=\mathrm{abs}\left(\mathrm{fft}\left({\mathrm{fwin}}_{\mathrm{k}}\right)/\mathrm{w}\right)$
9:	${\mathrm{A}}_{\mathrm{k}}{=\mathrm{A}}_{\mathrm{k}}(\min \_\mathrm{hr}\_\mathrm{freq}:\max \_\mathrm{hr}\_\mathrm{freq})$
10:	${\mathrm{HRFreqIndex}}_{\mathrm{k}}=\max \left({\mathrm{A}}_{\mathrm{k}}\right);$
11:	${\mathrm{hr}}_{\mathrm{k}}=\left(60*\frac{\mathrm{r}}{\mathrm{w}}\right){*(\mathrm{HRFreqIndex}}_{\mathrm{k}}+\min \_\mathrm{hr}\_\mathrm{freq}-2)$
12:	end for