The Measurement of Skin Color

Abstract

The colour of human skin is determined by its melanin content, its oxy- and deoxy-hemoglobin contents and the amount of endogenous or exogenous pigments such as bilirubin and carotene. The measurement of skin colour is of the autmost importance for many researchers and clinicians involved in dermatologic as well as cosmetic fields. The non-invasive measurement of epidermal melanin content is necessary in in vivo studies that implicate skin depigmentatiom and repigmentation. Skin eryhema values are considered as an index of inflammation, dermal vascularity/vasodilatation and are utilized in the evaluation of therapeutic outcome in several dermatologic treatments. The first quantitative evaluation of skin colour was accomplished in 1939 by Edwards and Duntley, who obtained colorimetric data specific for different types of skin pigmentation. Other authors subsequently utilised similar instruments to evaluate the skin colour of different ethnic groups. In the eighties, the calorimetric technology evolved greatly and sophisticated instruments suitable for dermatologic use became available.

It is important to note that although the in vitro colour measurement can be reliably done by several colorimetric devices, the quantification of skin colour « evolution » in vivo appears to be more complex, as in vivo fluctuations in erythema can affect melanin values and vice versa. Knowing that melanin absorbs light in a large range of wavelengths (including green, red and near-infrared light), the confusion over the discrimination between melanin and erythema can easily occur by colorimetric devices.