Abstract:

In the pursuit of tight and delicate skin, the problem of skin pores has attracted wide attention. Before that, few studies combined pore size, oil content and pore skin color for enlarged pore assessment. The aim of this study was to establish a new apparent pore classification system and a comprehensive and objective pore classification atlas. The researchers collected data from 120 healthy Chinese subjects using the VISIA-CR face imaging tester and the Sebumeter SM 815 skin oil content measuring instrument. Then, the self-built two-dimensional image processing algorithm was used for image analysis, and the pore index evaluation algorithm model was established by exploratory factor analysis. At the same time, the classification atlas was established, and the accuracy of the evaluation system was verified. As a result, the research team established a mathematical model using indicators such as oil content, skin color around pores （L^* value, a^* value, and b^* value）, and pore size （number of pores, pore area, pore area proportion and pore diameter）, and obtained the calculation formula: Apparent pore index=0.546* pore size factor+0.296* pore color factor+0.157* oil factor. And they build an intuitive pore grading criteria, which divided pores into mild, moderate and severe 3 grades, with the model score increasing as the grade increased. After verification, the Kappa coefficient is 0.72 （p<0.01）, indicating that the two methods were highly consistent, which proves that the established model and classification diagram are accurate. This study established an intuitive and quantitative map and a model for determining pore grade, and provided a scientific basis for the accurate evaluation of pore problems and the development of follow-up care products. The study can also be used in market development and consumer market research.

Key words: pore grading atlas, pore grading criteria, exploratory factor analysis, pore size