Table 2.

Spatial feature extracted from $\Delta HbO$.

Sr. No.	Statistical Feature	Mathematical Formulation/Description
1.	Signal Mean	Signal mean is calculated as: ${\mu }_w=\frac{1}{N_w}{\sum }_{k=k_L}^{k_U}△Hb{X}_w$ where, ${\mu }_w$: Mean of window w: sample window $N_w:$ Number of sample in the window $k_L$: Lower limit of the window $k_U:$ Upper limit of the window $△Hb{X}_w$: Stands for $\Delta HbO$ or $\Delta HbR$
2.	Signal Peak (Signal maximum)	The feature select the maximum value in the window.
3.	Signal Minimum	The feature minimum value in the window.
4.	Signal Skewness	Signal skewness is calculated as: $ske{w}_w=\frac{E_x{(\Delta Hb{X}_w-{\mu }_w)}^3}{{\sigma }^{{}^3}}$ where, $E_x$ is the expectation, $\mu$ is the mean, and $\sigma$ is the standard deviation of the haemoglobin $\Delta Hb{X}_w$
5.	Signal Kurtosis	Signal Kurtosis is calculated as: $Kur{t}_w=\frac{E_x{(\Delta Hb{X}_w-{\mu }_w)}^4}{{\sigma }^{{}^4}}$ where, $E_x$ is the expectation, $\mu$ is the mean, and $\sigma$ is the standard deviation of the haemoglobin $\Delta Hb{X}_w$
6.	Signal Variance	Signal variance is the measure of signal spread.
7.	Signal Median	Median is the value separating the higher half from the lower half of values in the time window.
8.	Peak-to-peak	Peak-to-peak is computed as the difference between the maximum to the minimum value in the time window.