"Ecce Homo" by Antonello da Messina, from non-invasive investigations to data fusion and dissemination.

Scientific investigations of artworks are crucial in terms of preservation since they provide a measurable evaluation of the materials and the state of conservation. This is the case of Antonello da Messina's painting "Ecce Homo": its delicate state of conservation, with the need for constant monitoring, required a broad and in-depth diagnostic campaign to support the restorers. The project was carried out entirely in situ using non-invasive cutting-edge techniques and proposes a multimodal and data-centric approach, integrating 3D and 2D methodologies. The surface irregularities and the support were analysed with a structured-light 3D scanner and X-ray tomography. The painting materials were investigated with X-ray fluorescence scanning (MA-XRF) and reflectance hyperspectral imaging (HSI). Primarily, the data were jointly used for a scientific scope and provided new knowledge of the painting in terms of materials and painting techniques. In addition, two web-based interactive platforms were developed: one to provide restorers and experts with a new perspective of the hidden geometries of the painting, and the other targeted at the general public for dissemination purposes. The results of the Ecce Homo scientific analysis were exhibited, using a touch-screen interface, and developed for different user levels, from adults to kids.

Macro and micro full field x-ray fluorescence with an X-ray pinhole camera presenting high energy and high spatial resolution.

This work describes a tabletop (50 cm × 25 cm × 25 cm) full field X-ray pinhole camera (FF-XPC) presenting high energy- and high spatial-resolution. The FF-XPC consists of a conventional charge-coupled device (CCD) detector coupled, in a coaxial geometry, to a pinhole collimator of small diameter. The X-ray fluorescence (XRF) is induced on the samples with an external low-power X-ray tube. The use of the CCD as an energy dispersive X-ray detector was obtained by adopting a multi-image acquisition in single photon counting and by developing a processing algorithm to be applied in real-time to each of the acquired image-frames. This approach allowed the measurement of X-ray spectra with an energy resolution down to 133 eV at the reference value of 5.9 keV. The detection of the X-ray fluorescence through the pinhole-collimator allowed the two-dimensional elemental mapping of the irradiated samples. Two magnifications (M), determined by the relative sample-pinhole-CCD distances, are used in the present setup. A low value of M (equal to 0.35×) allows the macro-FF-XRF of large area samples (up to 4 × 4 cm(2)) with a spatial resolution down to 140 µm; a large magnification (M equal to 6×) is used for the micro-FF-XRF of small area samples (2.5 × 2.5 mm(2)) with a spatial resolution down to 30 µm.