Analysis of melanin pigment changes in long terms for face of various ages: A case study on the UV care frequency

Abstract

In this study, we have analyzed individual differences in how the melanin component changes with time in 2003, 2010 and 2015. The frequency of use of protection against ultraviolet rays (UV) is considered to be a factor that causes individual differences in aging. Melanin is produced in human skin by exposure to UV, which promotes aging effects such as darkening and unevenness of skin color. In our previous work, we applied principal component analysis (PCA) to the distribution of melanin pigment and obtained feature values which quantitatively describe it. Furthermore, we found that the melanin component especially around the cheeks tends to increase with age. Comparing the melanin feature values for each frequency of use of UV protection, we found that the daily UV care even in winter can reduce the melanin component of face. In our previous work, we analyzed the database of facial images taken in 2003 and 2015. In this study, adding new facial data for 2010, we constructed a database of facial images captured in 2003, 2010, and 2015. It includes photographs of 60 subjects each in 3 years. The database also includes subjects’ frequency of using UV protection. Applying the same analysis as our previous study, we obtained principal component (PC) scores, which describe the changes in individuals’ faces in 2003, 2010 and 2015. From trends in these data, we found that the daily care for 12 years can suppress increasing the facial melanin component.