Recently, modern non-invasive digital imaging techniques for documentation and studying the painted artifacts in general and Coptic icons, in particular, enabled professional experts to study new artistic schools with discrimination of the original painting materials, underdrawings, artists’ techniques, and successive conservation interventions to conduct scientific conservation interventions. Multispectral imaging (MSI) is increasingly used in museums, galleries, and churches to provide comprehensive multi-wavelength digital images with a range of useful information that is likely hidden to the naked eye such as condition assessment, mapping pigments and organic varnishes, uncovering hidden signatures, diagnosing underlying, sketches, and investigating successive retouches. In this research, multispectral images were acquired with different spectral bands of high-resolution visible light (VIS), raking light (RAK), reflected and fluorescence ultraviolet (UVR, UVF), infrared fluorescence and reflectography (IRF, IRR), and raking light images to study two of Coptic icons from St. Demiana church, Boulaq, Cairo. Multispectral photos confirmed that the two studied icons were heavily retouched. Modifications on the original artist’s underdrawings were also detected in both studied icons. While the two studied Coptic icons were not signed by a specific artist, studying the artistic features of the icons and comparing them to the other published Coptic icons made attribution to Hafez Shamandi's artistic school.
Hanna et al. (Sun,) studied this question.