Consideration on the Cleaning Effect of Black Contaminants using Visible-Near-Infrared (VNIR) Hyperspectral Images

Abstract

VNIR hyperspectral images can be analyzed in situations involving color changes, such as before and after cleaning, without pre-treatment. In this study, to analyze the application of the VNIR hyperspectral system, we compared the black contaminants on the surface of the Jigwangguksa Pagoda upper stereobate at Beopcheonsa Temple, Wonju before and after cleaning with laser. After a preliminary experiment to evaluate the applicability of VNIR hyperspectral imaging, we took images of the four sides (north, south, east, and west). The 823 nm band image was used for comparing before and after cleaning. As per the result of the image differencing analysis about before and after cleaning, the spectral reflectance of the area where the cleaning was performed showed a tendency to increase. Additionally, it was found that not only the washed area but also the extent of change could be calculated through monochrome for quantitative comparison, and imaging analysis using the VNIR hyperspectral system was sufficiently effective for comparison before and after cleaning.