Imaging Cultural Heritage at Different Scales: Part I, the Micro-Scale (Manufacts)

Applications of non-invasive sensing techniques to investigate the internal structure and surface of precious and delicate objects represent a very important and consolidated research field in the scientific domain of cultural heritage knowledge and conservation. The present article is the first of three reviews focused on contact and non-contact imaging techniques applied to surveying cultural heritage at micro- (i.e., manufacts), meso- (sites) and macro-scales (landscapes). The capability to infer variations in geometrical and physical properties across the inspected surfaces or volumes is the unifying factor of these techniques, allowing scientists to discover new historical sites or to image their spatial extent and material features at different scales, from landscape to artifact. This first part concentrates on the micro-scale, i.e., inspection, study and characterization of small objects (ancient papers, paintings, statues, archaeological findings, architectural elements, etc.) from surface to internal properties

A literature analysis examining the potential suitability of terahertz imaging to detect friction ridge detail preserved in the imprimatura layer of oil-based, painted artwork

This literature analysis examines terahertz (THz) imaging as a non-invasive tool for the imaging of friction ridge detail from the first painted layer (imprimatura) in multilayered painted works of art. The paintings of interest are those created utilizing techniques developed during the Renaissance and still in use today. The goal of analysis serves to answer two questions. First, can THz radiation penetrate paint layers covering the imprimatura to reveal friction ridge information? Secondly, can the this technology recover friction ridge detail such that the fine details are sufficiently resolved to provide images suitable for comparison and identification purposes. If a comparison standard exists, recovered friction ridge detail from this layer can be used to establish linkages to an artist or between works of art. Further, it can be added to other scientific methods currently employed to assist with the authentication efforts of unattributed paintings. Flanked by the microwave and far-infrared edges, THz straddles the electronic and optic perspectives of the electromagnetic spectrum. As a consequence, this range is imparted with unique and useful properties. Able to penetrate and image through many opaque materials, its non-ionizing radiation is an ideal non-destructive technique that provides visual information from a painting’s sub-strata. Imaging is possible where refractive index differences exist between different paint layers. Though it is impossible, at present, to determine when a fingerprint was deposited, one can infer approximately when a print was created if it is recovered from the imprimatura layer of a painting, and can be subsequently attributed to a known source. Fingerprints are unique, a person is only able to deposit prints while their physical body is intact and thus, in some cases, the multiple layer process some artists use in their work may be used to the examiner’s advantage. Impressions of friction ridge detail have been recorded on receiving surfaces from human hands throughout time (and have also been discovered in works of art). Yet, the potential to associate those recorded impressions to a specific individual was only realized just over one hundred years ago. Much like the use of friction ridge skin, the relatively recently discovered THz range is now better understood; its tremendous potential unlocked by growing research and technology designed to exploit its unique properties

Digital Techniques for Documenting and Preserving Cultural Heritage

In this unique collection the authors present a wide range of interdisciplinary methods to study, document, and conserve material cultural heritage. The methods used serve as exemplars of best practice with a wide variety of cultural heritage objects having been recorded, examined, and visualised. The objects range in date, scale, materials, and state of preservation and so pose different research questions and challenges for digitization, conservation, and ontological representation of knowledge. Heritage science and specialist digital technologies are presented in a way approachable to non-scientists, while a separate technical section provides details of methods and techniques, alongside examples of notable applications of spatial and spectral documentation of material cultural heritage, with selected literature and identification of future research. This book is an outcome of interdisciplinary research and debates conducted by the participants of the COST Action TD1201, Colour and Space in Cultural Heritage, 2012–16 and is an Open Access publication available under a CC BY-NC-ND licence.https://scholarworks.wmich.edu/mip_arc_cdh/1000/thumbnail.jp

Imaging cultural heritage at different scales : part I, the micro-scale (manufacts)

Applications of non-invasive sensing techniques to investigate the internal structure and surface of precious and delicate objects represent a very important and consolidated research field in the scientific domain of cultural heritage knowledge and conservation. The present article is the first of three reviews focused on contact and non-contact imaging techniques applied to surveying cultural heritage at micro- (i.e., manufacts), meso- (sites) and macro-scales (landscapes). The capability to infer variations in geometrical and physical properties across the inspected surfaces or volumes is the unifying factor of these techniques, allowing scientists to discover new historical sites or to image their spatial extent and material features at different scales, from landscape to artifact. This first part concentrates on the micro-scale, i.e., inspection, study and characterization of small objects (ancient papers, paintings, statues, archaeological findings, architectural elements, etc.) from surface to internal properties.peer-reviewe

Digital Techniques for Documenting and Preserving Cultural Heritage

This book presents interdisciplinary approaches to the examination and documentation of material cultural heritage, using non-invasive spatial and spectral optical technologies

The brushstroke and materials of Amadeo de Souza-Cardoso combined in an authentication tool

Nowadays, authentication studies for paintings require a multidisciplinary approach, based on the contribution of visual features analysis but also on characterizations of materials and techniques. Moreover, it is important that the assessment of the authorship of a painting is supported by technical studies of a selected number of original artworks that cover the entire career of an artist. This dissertation is concerned about the work of modernist painter Amadeo de Souza-Cardoso. It is divided in three parts. In the first part, we propose a tool based on image processing that combines information obtained by brushstroke and materials analysis. The resulting tool provides qualitative and quantitative evaluation of the authorship of the paintings; the quantitative element is particularly relevant, as it could be crucial in solving authorship controversies, such as judicial disputes. The brushstroke analysis was performed by combining two algorithms for feature detection, namely Gabor filter and Scale Invariant Feature Transform. Thanks to this combination (and to the use of the Bag-of-Features model), the proposed method shows an accuracy higher than 90% in distinguishing between images of Amadeo’s paintings and images of artworks by other contemporary artists. For the molecular analysis, we implemented a semi-automatic system that uses hyperspectral imaging and elemental analysis. The system provides as output an image that depicts the mapping of the pigments present, together with the areas made using materials not coherent with Amadeo’s palette, if any. This visual output is a simple and effective way of assessing the results of the system. The tool proposed based on the combination of brushstroke and molecular information was tested in twelve paintings obtaining promising results. The second part of the thesis presents a systematic study of four selected paintings made by Amadeo in 1917. Although untitled, three of these paintings are commonly known as BRUT, Entrada and Coty; they are considered as his most successful and genuine works. The materials and techniques of these artworks have never been studied before. The paintings were studied with a multi-analytical approach using micro-Energy Dispersive X-ray Fluorescence spectroscopy, micro-Infrared and Raman Spectroscopy, micro-Spectrofluorimetry and Scanning Electron Microscopy. The characterization of Amadeo’s materials and techniques used on his last paintings, as well as the investigation of some of the conservation problems that affect these paintings, is essential to enrich the knowledge on this artist. Moreover, the study of the materials in the four paintings reveals commonalities between the paintings BRUT and Entrada. This observation is supported also by the analysis of the elements present in a photograph of a collage (conserved at the Art Library of the Calouste Gulbenkian Foundation), the only remaining evidence of a supposed maquete of these paintings. The final part of the thesis describes the application of the image processing tools developed in the first part of the thesis on a set of case studies; this experience demonstrates the potential of the tool to support painting analysis and authentication studies. The brushstroke analysis was used as additional analysis on the evaluation process of four paintings attributed to Amadeo, and the system based on hyperspectral analysis was applied on the painting dated 1917. The case studies therefore serve as a bridge between the first two parts of the dissertation

Draftsmanship, social networking, and cultural history : the portrait drawings of Hans Holbein the Elder (ca. 1465-1524)

Hans Holbein the Elder (ca. 1465-1524) was a successful and prolific painter and draftsman, who lived and worked mainly in the southern German city of Augsburg. In addition to being master of a workshop that produced large-scale religious works, Holbein produced numerous drawings, of which over two hundred have been preserved from throughout his career. The vast majority of Holbein’s surviving drawings – about one hundred sixty – are portraits or head studies, originally made in silverpoint in small, portable sketchbooks. The quantity and medium of his drawings indicate that taking portraits was a habitual part of Holbein’s practice, if not a preoccupation for him. His portrait drawings depict a range of Augsburg’s populace, including men, women, and children, representing a variety of social classes and professions. On several drawings he even identified his sitters clearly with inscriptions of their names, ages, occupations, or other claims to fame. Collectively, they offer the artist’s perspective on the bustling urban center in which he lived and worked as well as suggest his place within that milieu. This dissertation examines Holbein’s portrait drawings in terms of their material and technical production as well as their potential historical, social, and cultural significance. This study describes the characteristics that typify Holbein’s portrait drawings and establishes standards for attributing works to him, his workshop, and others, as well as offers paleographical analysis of his drawings’ inscriptions. Because his portraits present so much textual information that has otherwise been overlooked, questions of who the people of Holbein’s portraits are and what their portrayals reveal about themselves and about the artist can be considered. Applying sociological theories of social capital and networking, this study proposes that Holbein’s portrait drawings survive as important records of his social network and reveal insights into his social experiences and practices. Holbein’s portrait drawings also offer numerous social and cultural cues through his depictions of the clothes and adornments of his sitters. Finally, this project considers Holbein’s legacy in European portraiture, especially as inherited by his more famous son, Hans Holbein the Younger (1497/98-1543).Art Histor

Materials and production methods in 17th century portuguese illuminated cartography: a study of the maps in António Bocarro's "Book of the Plans of all Fortresses, Towns and Villages of the East Indies"

This thesis presents an interdisciplinary, multianalytical investigation of the early 17th-century illuminated maps of Pedro Baretto de Resende in the Antonio Bocarro’s Livro das plantas de todas as fortalezas, a codex made in Goa and currently housed at the Biblioteca Pública de Évora in Portugal. The work addresses previously unexplored aspects of the maps, including issues of authorship, the possibility of cross-cultural collaboration during their production, and the way their design and use of map signs depict late-stage empire. Using technical photography, FORS, h-XRF, Raman microscopy, μ-FT-IR, LC-DAD-MS, and vp-SEM-EDS, the maps’ materials and production methods were revealed and contextualized. The results are relevant to research concerning the connections between decorative cartography, economic and social history, and fine art. In addition, the findings contribute to the small but growing literature on the material characteristics of cartographic works. Finally, the work suggests a more holistic approach to the study of maps; RESUMO: Nesta tese é apresentada uma investigação interdisciplinar e multi-analítica dos mapas iluminados datados do início do século XVII de Pedro Baretto Resende no Livro de plantas de todas as fortalezas de António Bocarro, um códice produzido em Goa e que pode ser encontrado na Biblioteca Pública de Évora. O trabalho aborda aspectos anteriormente inexplorados destes mapas, incluindo questões de autoria, a possibilidade de colaboração intercultural durante sua produção e a forma como o design e o uso de sinalética são influenciados por um império em decadência. Usando técnicas de fotografia, FORS, FRX, microscopia Raman, micro-IV-TF, LC-DAD-MS e MEV-EDS, os materiais e métodos de produção dos mapas foram revelados e contextualizados. Os resultados são relevantes para o estudo das relações entre a cartografia decorativa, a económica e a história social, e as belas artes. Esta tese sugere ainda uma abordagem mais holística ao estudo de obras cartográficas

Santa Maria di Collemaggio Church (L’Aquila, Italy) : historical reconstruction by non-destructive testing techniques

The main goal of this work was the non-destructive testing (NDT) of an ancient fresco (15th century) preserved in the Santa Maria di Collemaggio Church (L’Aquila, Italy) and damaged after the 2009 earthquake. Active infrared thermography (IRT), near-infrared (NIR) reflectography and ultraviolet imaging (UV) were used. In addition, the state of the fresco prior to the earthquake was analyzed by electronic speckle pattern interferometry (ESPI), digital speckle correlation (DSC), raking light, tap, and chemical NDT techniques. The use of these techniques was important for the monitoring of new damages and for a comparison between the results over the years. Square heating thermography (SHT) data were processed using principal component thermography (PCT) and pulsed phase thermography (PPT) algorithms, in order to improve the defects’ signature and to reduce the impact of non-uniform heating and emissivity variations due to the painting’s pigments. A multi-analysis approach, segmentation operators and a specific data correlation method emphasize the overall study of the fresco. Furthermore, the facade and the high altar area were inspected by passive thermography and ground-penetrating radar (GPR), respectively. In the present case, the combined use of NDT techniques was useful to fill in the gaps in the construction history of the building

Investigation of the complementary use of non-invasive techniques for the holistic analysis of paintings and automatic analysis of large scale spectral imaging data

The analysis of painting materials and methods is acknowledged for providing important information to art history. This study illustrates a detailed examination of the characteristics, advantages and capabilities that the combined application of a variety of non-invasive techniques, ranging from spectral imaging and optical coherence tomography (OCT), to fibre optics reflectance spectroscopy (FORS), X-ray Fluorescence (XRF) and Raman spectroscopy, has to offer. The analysis of painting materials is seen under the prism of a holistic examination of different types of cultural heritage objects. More specifically, the limitations that the individual techniques face and, most importantly, how their complementary use can overcome them are thoroughly investigated through the examination of a large and heterogeneous statistical sample, in a completely novel way. The heterogeneity of the sample is related both to the painting materials (i.e pigments, binding media and substrates) and the degradation level (i.e. paintings stored in storages of museum and murals of caves that are exposed in the environmental conditions of the desert). For the extraction of accurate conclusions about the painting materials and methods applied in a specific period, the examination of large number of artworks of this period is required. PRISMS, the spectral imaging system developed by our group enables the time efficient imaging of large painting surfaces, leading to the acquisition of large scale spectral imaging data, which makes such an analysis faster, more cost-effective and less laborious without diminishing the quality of the results. This study proposes methods based on the statistical analysis for the automatic processing of the spectral imaging data in two directions: the revealing of information that is obvious under visual observation and clustering of the spectral information. With regards to the automatic revealing of hidden information, the potential of principal component analysis (PCA) and independent principal analysis (ICA), two of the most commonly used statistical analysis methods, were examined giving very good results. In addition, the development of a new method for the automatic clustering of large scale spectral information based on the 'Self-organised mapping' (SOM) method is presented. The spectral feature of the analysed areas in the UV-VIS/NIR (400-900 nm) is indicative for its pigment composition, therefore the automatic clustering of the pixel-level spectral information that the PRISMS system provides can classify the areas according to their pigment composition. The application of statistical analysis methods in the preliminary stage of the analysis of large number of artworks (e.g. large painting collections) of large surface painting areas (e.g. murals) is of significant importance; as they highlight the areas that should be examined in detail. The multimodal non-invasive approach was applied on the examination of three artworks of significant importance for East Asian art history; the cave 465 of the Mogao complex in China, the export Chinese watercolor paintings from the collections of the Victoria and Albert (V&A) museum and the Royal Horticulture Society (RHS) and the Selden map. The examination of these three works of art, in addition to providing a wide and heterogeneous sample for the detailed examination of the multi-modal approach, has also helped addressing several historical questions