Practical Measurement and Neural Encoding of Hyperspectral Skin Reflectance

We propose a practical method to measure spectral skin reflectance as well as a spectral BSSRDF model spanning a wide spectral range from 300nm to 1000nm. We employ a practical capture setup consisting of desktop monitors to illuminate human faces in the visible domain to estimate five parameters of spectral chromophore concentrations including melanin, hemoglobin, and $\beta$ carotene concentration, melanin blend-type fraction, and epidermal hemoglobin fraction. The estimated parameters make use of a novel three-stage lookup table search for faster parameter fitting, and drive our skin model for accurate reconstruction of facial skin reflectance response in both the visible domain as well as in the UVA and near-infrared range. We also propose a novel neural network architecture that given our measurements, predicts the five chromophore parameters of our model at the encoder stage and full hyperspectral reflectance response as the output of the decoder stage.