In this paper, skin tone heterogeneity in five facial areas (forehead, right cheekbone, left cheekbone, nose tip and chin) was investigated under six light sources with correlated color temperature (CCT) of 2850 K, 3500 K, 5000 K, 5500 K, 6500 K and 9000 K. Firstly, a facial image capturing protocol was developed and applied to five female participants, and their facial skin tone was analyzed based on the captured images. Through color characterization of the camera, XYZ values in each facial area were converted by a matrix from the extracted RGB data and then transformed to CAM02-UCS color space. MCDM with CAM02-UCS color difference was used to quantify skin tone heterogeneity in each facial area. The results under different light sources indicated that larger heterogeneity exists under the light source with lower CCT, and when the CCT of the light source ranges from 5000 K to 9000 K, there was smaller skin tone heterogeneity in each facial area.
Ruili He, Kaida Xiao, Michael Pointer, Stephen Westland, "Assessing skin tone heterogeneity under various light sources" in Proc. IS&T London Imaging Meeting 2020: Future Colour Imaging, 2020, pp 5 - 9, https://doi.org/10.2352/issn.2694-118X.2020.LIM-15