title: Accurate Measurements of Spectral Reflectance in Picasso's Guernica Painting.
abstract: The use of non-invasive spectral measurements to control the conservation status is a part of the preventive conservation of artworks which nowadays is becoming increasingly interesting. This paper describes how to use a spectral measuring device and an illumination system specifically designed for such a task in a very large dimension artwork painting (7.8 m wide × 3.5 m high). The system, controlled by a Cartesian robot, allows spectral measurements in a spectral range of 400-780 nm. The measured data array has a total of 2201 circular regions with 5.5 mm spot diameter placed on a square grid. Colorimetric calculations performed from these spectral measurements may be used to characterize color shifts related to reflectance changes in specific areas of the paint. A color shifting from the expected gray has been shown.
authors.affiliation: Departamento de Óptica, Universidad Complutense de Madrid, Facultad de Óptica y Optometría, Madrid, Spain.
authors.forename: Javier Muñoz
authors.initials: JM
authors.lastname: de Luna
authors.affiliation: Departamento de Óptica, Universidad Complutense de Madrid, Facultad de Óptica y Optometría, Madrid, Spain Departamento de Ingeniería y Gestión Forestal y Ambiental, Universidad Politécnica de Madrid, Madrid, Spain.
authors.forename: Antonio Alvarez
authors.initials: AA
authors.lastname: Fernandez-Balbuena
authors.affiliation: Departamento de Óptica, Universidad Complutense de Madrid, Facultad de Óptica y Optometría, Madrid, Spain dvazquez@ucm.es.
authors.forename: Daniel
authors.initials: D
authors.lastname: Vázquez
authors.affiliation: Departamento de Óptica, Facultad de Ciencias (Edificio Mecenas), Universidad de Granada, Granada, Spain.
authors.forename: Manuel
authors.initials: M
authors.lastname: Melgosa
authors.affiliation: Departamento de Restauración, Museo Nacional Centro de Arte Reina Sofía, Madrid, Spain.
authors.forename: Humberto
authors.initials: H
authors.lastname: Durán
authors.affiliation: Departamento de Restauración, Museo Nacional Centro de Arte Reina Sofía, Madrid, Spain.
authors.forename: Jorge
authors.initials: J
authors.lastname: García
authors.affiliation: Departamento de Restauración, Museo Nacional Centro de Arte Reina Sofía, Madrid, Spain.
authors.forename: Carmen
authors.initials: C
authors.lastname: Muro
keywords: Color shift; Colorimetry; Guernica; Pablo Picasso; Spectral measurements