Figures 4(a) and 4(b) show the relative percent changes from baseline melanin concentration for NIR only, Vis only, and our layered model approach across all skin types imaged in this study. The magnitude of errors are larger in the venous occlusion case, given the greater change (increase) in the overall tissue absorption due to the blood pooling that occurs during the occlusion phase of the measurements. Averaging across all skin types, there was cross-talk error derived from using NIR spectra only, from visible spectra, whereas the layered model produced mean errors of . As total hemoglobin concentration is kept approximately constant during the arterial occlusion phase, total absorption values did not change significantly. There was a transition from spectral features of oxygenated to deoxygenated hemoglobin. In these arterial occlusions, the overall magnitudes of cross-talk errors were lower; however, the mean errors from the NIR regime decomposition remained relatively higher than the other methods, while the layer model approach provided the minimal error. Here, the mean cross-talk errors were , , and for the NIR regime, visible regime, and layered model, respectively.