Development Of A Skin Colour Gamut For Skin Colour Reproduction

Objectives: The purpose of this study was to establish a unique colour gamut for human skin in order to provide a basic guideline for developing a fully automated method of manufacturing soft tissue prostheses using advanced manufacturing technologies. Methods: Ethics approval was obtained from the University of Sheffield UREC to carry out this study on volunteers. A target was set to obtain direct colour measurements from 100 individuals from each of six ethnic groups. The measurements were conducted by using a CM 2600d spectrophotometer under standard D65 illuminant. Both CIE XYZ tristimulus values and spectral reflectance were measured for each subject for 9 different body positions on the face and arms. An advanced colour appearance model was adopted to predict human perceptual attributes for skin colour and a 3D colour gamut was constructed using a Segment Maxima GBD (SMGBD). Results: To date we have collected data for 49 Caucasians and the preliminary colour gamut for this ethnic group has been determined. The main variation for skin colours was in the value of the hue, while chroma was the most consistent attribute across the group. A consistent colour shift between facial colour and the colour of the arm was identified. There is a clear trend that the facial colour tends to have a more enhanced red component when compared to the arm colour - indicated by a significant shift in hue and chroma whilst lightness is maintained. Conclusion: The development of a skin colour gamut for Caucasians has been achieved by direct colour measurement, colour appearance prediction and 3D reconstructions. Further data collection is required to establish the colour gamut for other ethnic groups.