Fig. 3.

Geometric explanation for calculation of contribution ratios ($r$) of deep and shallow signals in original NIRS signal under two $x$-intercept conditions: (a) $X{i}_{\mathrm{ex}}<X{i}_{\mathrm{gr}}$ and (b) $X{i}_{\mathrm{ex}}\ge X{i}_{\mathrm{gr}}$. The deep-layer contribution ratios for component Ci are expressed as $r_{\mathrm{dp}}^{Ci}=B/A$ in (a) and $r_{\mathrm{dp}}^{Ci}=B/(2B-A)$ in (b).