An explorative chemometric approach applied to hyperspectral images for the study of illuminated manuscripts

Emilio Catelli; Lise Lyngsnes Randeberg; Bjørn Kåre Alsberg; Kidane Fanta Gebremariam; Silvano Bracci

doi:10.1016/j.saa.2017.01.015

An explorative chemometric approach applied to hyperspectral images for the study of illuminated manuscripts

Spectrochim Acta A Mol Biomol Spectrosc. 2017 Apr 15:177:69-78. doi: 10.1016/j.saa.2017.01.015. Epub 2017 Jan 7.

Authors

Emilio Catelli¹, Lise Lyngsnes Randeberg², Bjørn Kåre Alsberg³, Kidane Fanta Gebremariam³, Silvano Bracci⁴

Affiliations

¹ Department of Chemistry, Norwegian University of Science and Technology (NTNU), N-7491 Trondheim, Norway. Electronic address: emilio.catelli@ntnu.no.
² Department of Electronics and Telecommunications, Norwegian University of Science and Technology (NTNU), N-7491 Trondheim, Norway.
³ Department of Chemistry, Norwegian University of Science and Technology (NTNU), N-7491 Trondheim, Norway.
⁴ Catholic Diocese of Fano, Italy.

PMID: 28126654
DOI: 10.1016/j.saa.2017.01.015

Abstract

Hyperspectral imaging (HSI) is a fast non-invasive imaging technology recently applied in the field of art conservation. With the help of chemometrics, important information about the spectral properties and spatial distribution of pigments can be extracted from HSI data. With the intent of expanding the applications of chemometrics to the interpretation of hyperspectral images of historical documents, and, at the same time, to study the colorants and their spatial distribution on ancient illuminated manuscripts, an explorative chemometric approach is here presented. The method makes use of chemometric tools for spectral de-noising (minimum noise fraction (MNF)) and image analysis (multivariate image analysis (MIA) and iterative key set factor analysis (IKSFA)/spectral angle mapper (SAM)) which have given an efficient separation, classification and mapping of colorants from visible-near-infrared (VNIR) hyperspectral images of an ancient illuminated fragment. The identification of colorants was achieved by extracting and interpreting the VNIR spectra as well as by using a portable X-ray fluorescence (XRF) spectrometer.

Keywords: Chemometrics; Colorants; Illuminated manuscripts; VNIR hyperspectral imaging.