Hyperspectral image reconstruction of heritage artwork using RGB images and deep neural networks

The application of our research is in the art world where the scarcity of available analytical data from a particular artist or physical access for its acquisition is restricted. This poses a fundamental problem for the purpose of conservation, restoration or authentication of historical artworks. We address part of this problem by providing a practical method to generate hyperspectral data from readily available RGB imagery of artwork by means of a two-step process using deep neural networks. The particularities of our approach include the generation of learnable colour mixtures and reflectances from a reduced collection of prior data for the mapping and reconstruction of hyperspectral features on new images. Further analysis and correction of the prediction are achieved by a second network that reduces the error by producing results akin to those obtained by a hyperspectral camera. Our method has been used to study a collection of paintings by Amadeo de Souza-Cardoso where successful results were obtained. CCS CONCEPTS • Computing methodologies → Neural networks; Artificial intelligence; • Applied computing → Arts and humanities.info:eu-repo/semantics/publishedVersio

A closer look at radiation, colour and museum lighting topics

Funding Information: Research funding: This work was supported by National Funds through FCT-Portuguese Foundation for Science and Technology under the Projects (UIDB/50006/2020 and UIDP/50006/2020 – LAQV; and UIDB/00729/2020 and UIDP/00729/2020 – VICARTE). Publisher Copyright: © 2023 the author(s), published by De Gruyter, Berlin/Boston 2023.Introduction to Conservation Science (ICS) is a curricular unit (CU) from the bachelor's degree in Conservation-Restoration at NOVA School of Science and Technology. This CU was created in 2017 to fill a gap in the academic degree - the need for a bridge between fundamental sciences (1st year) and conservation-restoration diagnosis (3rd year). For this reason, ICS was designed with the main goal of teaching 2nd year students how to look at, approach and solve problems of Cultural Heritage, through the combination of reflexive thinking and object-led analysis. ICS was first designed by an expert in Conservation Science with academic background in physics. However, from the perception of the students' struggle to understand the purpose of ICS subjects to their future professional activity, a professor with expertise in Conservation and Restoration was invited in 2019 to work together in the re-design of the CU, through an integrated approach between the two experts. ICS was then revised with the introduction of new perspectives and topics, as well as new communication routes to students. This work highlights this partnership as a good practice methodology to involve conservation-restoration students into science, focusing on the ICS classes specifically dedicated to radiation, colour, and museum lighting.publishersversionpublishe

Estudo do efeito da adição de iões metálicos na corrosão de vidros potássicos

Dissertação apresentada para obtenção do Grau de Doutor em Conservação e Restauro, especialidade em Ciências da Conservação, pela Universidade Nova de Lisboa, Faculdade de Ciências e TecnologiaFragmentos de vitrais do séc. XV, provenientes do Mosteiro de Santa Maria da Vitória (Batalha), foram analisados pela primeira vez, de forma sistemática, de forma a obter-se um termo de referência para o estudo da corrosão de vidros potássicos antigos. Pare este estudo recorreu-se às espectroscopias de feixes de iões e de infravermelhos, tendo-se determinado que os vidros de base são formados por misturas de óxidos de Si, K, Ca, e de óxidos de Mn, Fe e Cu, usados como corantes, em composições que estão de acordo com o receituário da época. As grisalhas revelaram-se misturas de óxidos de Si e Pb, com elevadas concentrações de Fe e Cu, e também de Zn, cuja presença é notável uma vez que não se encontra habitualmente associado com aqueles metais. A camada de corrosão mostrou-se formada por carbonatos e oxalatos de Ca. Estabelecida a composição de referência, pretendeu-se estudar neste trabalho o efeito da introdução de elementos de coloração na deterioração de vidro potássico em presença de água, para compreender os mecanismos de corrosão dos vitrais medievais,essencial a um trabalho de conservação adequado. Assim, produziram-se vidros modelo com composições SiO2−CaO−K2O semelhantes às encontradas nos vitrais do Mosteiro da Batalha, a que foram adicionados óxidos de Cu, Fe ou Mn, isoladamente ou em combinação. Estes vidros foram sujeitos a ensaios de imersão em água de forma a simular ambientes de elevada humidade. A corrosão e a sua progressão foram caracterizadas por técnicas espectroscópicas de feixes de iões e de infravermelhos com transformada de Fourier, e por microscopia óptica, em combinação com a avaliação das alterações da solução aquosa, em particular o seu pH. As condições de testes exploradas, com e sem agitação do meio, conduziram a diferentes morfologias de superfície associadas com as diferentes taxas da corrosão. Mostra-se que se formam camadas superficiais de carbonato de Ca, e uma camada rica em Si nos períodos mais longos da imersão. Para além destas, encontram-se camadas enriquecidas nos elementos da transição, e uma corrosão inicial mais rápida nos vidros dopados com Cu. Este trabalho mostra que as condições experimentais escolhidas reproduzem bem a forma de corrosão encontrada nos vidros antigos de composição similar e sujeitos às condições atmosféricas ao longo de cinco séculos, e que o pH pode ser um bom parâmetro para estudar as cinéticas da corrosão em condições de humidade elevada

Defining the first preventive conservation guidelines for hand-painted magic lantern glass slides

The authors acknowledge the support of the Portuguese Foundation for Science and Technology (FCT-MCTES), through the doctoral program CORES-PD/00253/2012, for the PhD grant PD/BD/136694/2018 (Ângela Santos), and Research Unit VICARTE (UIDB/00729/2020). This research has benefited from the use of the infrastructure PRISC (Portuguese Research Infrastructure of Scientific Collections). The authors are also grateful to all the institutions and individuals that accepted to participate in the online survey, and to the Portuguese Cinematheque – Museum of Cinema, and National Museum of Natural History and Science of the University of Lisbon for the collaboration with the project "Lanterna Magica – Technology and Preservation of Painted Glass Slides for Projection with Magic Lanterns". The authors would also like to acknowledge for the relevant comments of the reviewers that significantly contributed to the improvement of the manuscript.This article intends to define and make available guidelines for the preventive conservation of hand-painted glass slides for magic lanterns, the first optical instruments for the projection of images, invented in the 17th century. For this purpose, around 300 hand-painted glass slides from the Portuguese Cinematheque - Museum of Cinema (CP) and Nacional Museum of Natural History and Science of the University of Lisbon (MUHNAC), were studied in terms of representativity in these collections, discursive genre, type of construction or movement mechanism, state of preservation and degradation problems. A survey was designed and distributed to institutions across the globe aiming for an overview of the formal characteristics of the collections of magic lantern slides and the preventive and interventive conservation measures undertaken. The guidelines are focused on the environmental conditions (temperature, relative humidity, and light), fine particles and pest control, storage and display conditions and materials, as well as handling. Recommendations on performative projections or demonstrations are also provided.publishersversionpublishe

Monitoring the Natural Heating of Two Art Nouveau Glass Windows by Infrared Thermography

UID/EAT/00729/2019 SFRH/BPD/108403/2015publishersversionpublishe

A new and simple optical sensor for the detection of formic acid unleashed by wooden storage or display materials used in museums and responsible for accelerating glass deterioration

Organic pollutants such as formic acid , acetic acid and formaldehyde released by some materials (mainly wood) used for storage and display can play an important role on the alteration of the glass structure due to the alkali leaching process. It as been determined that formic acid when present inside storage or display cabinets is the one that affects most glass integrity , accelerating and deepening the alkali leaching from the silica matrix. As this situation can affect many museums on their glass collections , monitoring this compound would be of great importance for indoor preservation purposes. An optical sensor based on the layer-­‐by-­‐layer (LbL) electrostatic self-­‐assembly process is under development to identify indoor formic acid based on the immobilization of chemo-­‐responsive dyes in polymeric structures. The sensors are based on an optical response resulting from the reaction between immobilized dyes and the referred organic pollutant .publishersversionpublishe

The technology of copper-based red glass sectilia from the 2nd century ad lucius verus villa in rome

PD/BD/135053/2017This work aimed to investigate the origin of different red hues of Roman copper-based red opaque glass sectilia, to shed light on the production technology behind them. This objective was achieved by the depth study of the samples of glass sectilia, which decorated the villa of co-Emperor Lucius Verus (161–169 AD). These were selected for analysis due to their abundance, the certainty of their date and of their different red and orange hues. Using OM (optical microscopy), colourimetry and FORS (fibre optical reflectance spectroscopy) spectroscopy, four red and four orange hues were individuated. A set of representative samples for each hue was analysed by EPMA (electron probe microanalyses) to detect any correlation between colour and chemical composition. Crystalline phases were investigated through high-resolution FEG–SEM (field emission gun scanning electron microscope), µRaman spectroscopy and XRD, for the identification of colouring and opacifying agents and to understand how the different hues are affected by their shape, concentration and dimension. Sub-micrometric particles of metallic copper and cuprite crystals were identified as both the colouring and opacifying agents. These were not present in the same samples and were manufactured by two distinct colouring techniques, corresponding to two different glass chemical compositions. The size and the number of the colouring particles were the main factors that distinguished one hue from another. Although produced through different colouring techniques, some red samples appeared to be very similar to each other. These data enrich a period of the Roman age through some analyses and allow the identification of the type, as well as some of the production conditions of opaque red glass produced during 2nd century AD, which could be considered to be a period of transition from one technology to another.publishersversionpublishe

The Influence of Raw Materials on the Stability of Grisaille Paint Layers

This research was funded by Fundação para a Ciência e Tecnologia de Portugal (project UIDB/50025/2020-2023, researcher grant CEECIND/02249/2021. Publisher Copyright: © 2022 by the authors.Grisaille is a glass-based paint made by mixing metal oxides (iron or copper) with ground lead-silica glass. The different materials used in the grisailles production (coloring agents, base glasses, or vehicles) can significantly impact their long-term stability along with the firing conditions. The main objective of this study was to achieve a better understanding of how raw materials influence the production and stability of these paints. To achieve this goal, 27 grisailles were produced, changing the raw materials, proportions, and firing conditions. The produced grisailles were characterized by X-ray fluorescence and diffraction, colorimetry, roughness measurement, and contact angle analysis. Adhesion and cleaning tests were also made. The use of different coloring agents has a significant impact on the final appearance and on the chemical and mechanical stability of the grisailles, but the latest is more affected by both firing temperature and the proportion between pigments and base glasses.publishersversionpublishe

Análise do risco de crédito de empresas: aplicação ao caso da Ydreams

Mestrado em Contabilidade e Análise FinanceiraUma empresa entra em incumprimento quando não gera fluxos de caixa suficientes para cumprir as suas responsabilidades financeiras, situação que, quando em casos extremos, pode conduzir a empresa a um processo de falência. Dependendo o risco de incumprimento de diversos fatores, como sejam a capacidade de concessão de crédito e o setor de atividade, nesta dissertação proponho-me a fazer um estudo de caso sobre a análise da queda da empresa tecnológica Ydreams, antes apontada como um exemplo de projeto de inovação empresarial bem sucedido. O objetivo do trabalho é tentar perceber se já existiam previamente indícios de um elevado risco de crédito nesta empresa, quando ela se apresentava como uma das empresas mais promissoras no setor tecnológico em Portugal. Esta análise será feita através dos modelos e técnicas de análise de risco de crédito, que servem de base para tomadas de decisões de gestão, de investimento, bem como de crédito. Pretendo com este estudo responder à seguinte questão: será que os modelos anteciparam devidamente os problemas que posteriormente se observaram na Ydreams?A company goes into default when it does not generate enough cash flows to meet its financial responsibilities, which under extreme circumstances may lead the firm into bankruptcy. Considering that the risk of default depends on several factors, such as lending capacity and the business sector, in this work I propose to do a case study on the analysis of the fall of the technology company Ydreams. The goal is to try to understand if there were already prior signs of high risk of failure of what was considered one of the most promising companies in the technology sector in Portugal. This analysis will be done through the application of credit risk models and default risk analysis techniques, which are the basis for taking management decisions, doing investments, as well as taking credit decisions. In this study I intend to answer the following question: did the models anticipated properly the problems later observed in Ydreams?N/

Nanotechnology in Roman Opaque Red Glass from the 2nd Century AD. Archaeometric Investigation in Red Sectilia from the Decoration of the Lucius Verus Villa in Rome

PD/BD/135053/2017 UID/EAT/00729/2019This work aims to characterise the chemical composition of Roman opaque red glass sectilia dated to the 2nd century A.D and to shed light on Roman glassmaking production of different shades of red, from red to reddish-brown. Due to the lack of technical historical sources for this period many questions about technological aspects still remain. In this project a multi-disciplinary approach is in progress to investigate the red glass sectilia with several red hues from the Imperial Villa of Lucius Verus (161–169 A.D.) in Rome. First, colorimetric measurements were taken to identify the various red hues. The second step was chemical characterization of the samples and the identification of crystalline colouring phases. Particle Induced X-Ray Emission (PIXE) analysis was used to investigate the chemical composition of these glass samples, while the crystalline phases were identified by Raman Spectroscopy and Scanning Electrons Microscope with Energy Dispersive X-ray Spectrometry (SEM-EDS). Using SEM-EDS nanoparticles were detected as a colouring agent, the chemical composition and the morphology of which has been studied in depth. This information has been compared with the colorimetric analysis to establish any correlation with the different colour hues.publishersversionpublishe