Measurement of skin texture through polarization imaging

Abstract

Determination of skin surface texture is of particular importance in the field of dermatology as such measurements can be used for skin diagnostics and evaluation of therapeutic or cosmetic treatments. Profilometry of skin replicas, three-dimensional imaging and computer vision have been successfully used to measure and document skin texture. Nevertheless, the development of a simpler and faster technique may prove to be advantageous in a clinical setting. We propose the use of polarization imaging with high angles of incidence as a simple alternative to measure/document skin texture/roughness. A system based on digital photography and polarization optics was developed to acquire and compute texture images. Optimization of the system configuration was conducted to enhance the contrast for measuring skin roughness. The method was validated against roughness standards and tested in clinical studies. Measurements were made in subjects aged from 9 to 70 years and image analysis was used to evaluate texture. The developed texture scale was shown to correlate closely to the results from clinical assessment and from roughness standards. Frequency domain analysis showed a significantly different power spectrum for the texture images of young subjects when compared with older subjects. The evaluation of texture as a function of age showed that facial skin roughness increased linearly from teenage to 40 years followed by a plateau thereafter. The system proved to be a useful clinical tool for assessing skin texture. The age-related results may indicate that some skin texture features are formed before the age of 40 years.