Resumo
Countless images and texts have been accidentally or intentionally obscured on paintings, books and documents, in archaeological sites, museums, libraries and archives across the world, due to multiple causes, such as fire and flood damage, light fading, biodeterioration, overpainting, palimpsests... Often considered irrecoverable by conventional conservation methods, what new knowledge could be unlocked from this “lost” heritage, if we were able to see those invisible images and read those illegible texts? The present project aims to: 1) optimise and apply advanced imaging techniques and image processing methods to digitally recover a wide range of deteriorated heritage, 2) research and contextualise the recovered images and texts and 3) make them accessible to researchers and the general public through a virtual museum.The variety and complexity of the materials investigated (pigments, binding media, inks, photographic emulsions...), of the supports of images and text (paper, parchment, canvas, panel, wall...) and of the conservation problems that affect their visualisation, require a versatile and powerful methodology. Therefore, complementary imaging techniques will be used, such as UV-VIS-NIR multiband and hyperspectral imaging in 2D and 3D, X-Ray Fluorescence scanning or Raman imaging. Image processing methods like Principal Component Analysis, Spectral Angle Mapper and Elemental Subtraction will also be tested to improve the contrast of the images and the readability of the text.The project builds and expands on previous experience at the National Archives of the UK and this presentation shows the results of applying the aforementioned methodologies to a range of representative examples of cultural heritage from the Iberian Peninsula that is often affected by visibility/readability issues, such as Palaeolithic rock art, Medieval manuscripts written with iron gall ink on parchment and 19th century photographs. The results obtained with the different imaging techniques will be discussed, and their benefits and challenges presented.