The man who became a Blue Glass. Reflectance hyperspectral imaging discloses a hidden Picasso painting of the Blue period

Reflectance hyperspectral imaging (HSI) in the Visible and Near-IR (VNIR) to the Short Wave IR (SWIR) ranges is acknowledged as one of the most effective techniques for non-invasive examination of paintings. Recently, in some important museums worldwide a new trend has emerged towards a more systematic use of reflectance HSI, which is applied as advanced imaging technique to attain at once analysis and documentation of the painted surfaces and inner layers. As an example of this trend, in the framework of the interdisciplinary program "Picasso: Blue Project" recently carried out at the Museu Picasso in Barcelona, a selection of paintings of the Blue Period (1901-1904) collection were revisited through the eye of cutting-edge analytical techniques, including reflectance HSI. The present paper focuses on the painting "The Blue Glass" (La Copa Blava, 1903), which was examined by using a high-performance reflectance HSI instrumentation. Under its visible surface, this iconic oil on canvas featured a stratification of different compositions that perfectly witnessed the Picasso's creative process. The HSI data enabled an unprecedented visualisation of the artistic metamorphosis of this painting. The well-known Picasso's creative practice of repainting on his own canvas was brought to the light by means of HSI images, which offered unique materials for visualising the hidden layers of the painting, by disclosing subsequent and unknown earlier versions and the artistic evolution of the painting. The outcomes of the project were disseminated in an exhibition, that addressed the ambitious objective of sharing with the wide public scholarly advanced knowledge hitherto gained on the Picasso Blue Period. Within this context, reflectance HSI proved to be exceptionally effective, not only for addressing analytical tasks, but also for educational purposes. & COPY; 2023 Consiglio Nazionale delle Ricerche (CNR). Published by Elsevier Masson SAS. All rights reserved.