Hyper-Spectral Imaging Technique: Application for Colorimetric Analysis of Paintings

Collaboration with curators and conservators is of utmost importance when working with Hyper- Spectral Imaging (HSI) technique as the instrumentation and experimental protocols have to match their requested requirements. Other recommendations that need to be followed when acquiring data with an illumination/observation geometry configuration are those issued by the Commission Internationale de l'Eclairage (CIE) for calibrated RGB images and colorimetric values. The difficulties related to obtaining accurate, reliable, and reproducible data suitable for matching the colorimetric calculations as required by CIE result in the still rare application of HSI technique in the art field for colorimetric analysis of paintings before and after restoration. This paper describes the HSI scanner developed at IFAC-CNR for non-invasive diagnostics and accurate color acquisitions on paintings and will discuss HSI measurements focused on color evaluation of the paint surface of a 15th century panel painting before and after the challenging restoration operations.