title: In Situ Identification of Pigment Composition and Particle Size on Wall Paintings Using Visible Spectroscopy as a Noninvasive Measurement Method.
abstract: Noninvasive examination methods of chemical composition and particle size are presented here based on visible spectroscopy to achieve the identification and recording of mineral pigments used on ancient wall paintings. The normalized spectral curve, slope and curvature extracted from visible spectral reflectance are combined with adjustable weighting coefficients to construct the identification feature space, and Euclid distances between spectral reflectance from wall paintings and a reference database are calculated in the feature space as the discriminant criterion to identify the chemical composition of mineral pigments. A parametric relationship between the integral quantity of spectral reflectance and logarithm of mean particle size is established using a quadratic polynomial to accomplish the noninvasive prediction of mineral pigment particle size used on ancient wall paintings. The feasibility of the proposed methods is validated by the in situ nondestructive identification of the wall paintings in the Mogao Grottoes at Dunhuang. Chinese painting styles and historical evolution are then analyzed according to the identification results of 16 different grottoes constructed from the Sixteen Kingdoms to the Yuan Dynasty.
authors.affiliation: School of Printing and Packaging, Wuhan University, China.
authors.forename: Junfeng
authors.initials: J
authors.lastname: Li
authors.affiliation: School of Printing and Packaging, Wuhan University, China wan@whu.edu.cn.
authors.forename: Xiaoxia
authors.initials: X
authors.lastname: Wan
authors.affiliation: School of Printing and Packaging, Wuhan University, China.
authors.forename: Yajing
authors.initials: Y
authors.lastname: Bu
authors.affiliation: School of Printing and Packaging, Wuhan University, China.
authors.forename: Chan
authors.initials: C
authors.lastname: Li
authors.affiliation: School of Printing and Packaging, Wuhan University, China.
authors.forename: Jinxing
authors.initials: J
authors.lastname: Liang
authors.affiliation: School of Printing and Packaging, Wuhan University, China.
authors.forename: Qiang
authors.initials: Q
authors.lastname: Liu
keywords: Visible spectroscopy; absorption and scattering; ancient wall paintings; chemical composition identification; mineral pigment identification; non-contact measurement; particle size identification