Digital image processing of the Ghent altarpiece : supporting the painting's study and conservation treatment

In this article, we show progress in certain image processing techniques that can support the physical restoration of the painting, its art-historical analysis, or both. We show how analysis of the crack patterns could indicate possible areas of overpaint, which may be of great value for the physical restoration campaign, after further validation. Next, we explore how digital image inpainting can serve as a simulation for the restoration of paint losses. Finally, we explore how the statistical analysis of the relatively simple and frequently recurring objects (such as pearls in this masterpiece) may characterize the consistency of the painter’s style and thereby aid both art-historical interpretation and physical restoration campaign

A knowledge based architecture for the virtual restoration of ancient photos

Historical images are essential documents of the recent past. Nevertheless, time and bad preservation corrupt their physical supports. Digitization can be the solution to extend their \u201clives\u201d, and digital techniques can be used to recover lost information. This task is often difficult and time-consuming, if commercial restoration tools are used for the purpose. A new solution is proposed to help non-expert users in restoring their damaged photos. First, we defined a dual taxonomy for the defects in printed and digitized photos. We represented our restoration domain with an ontology and we created some rules to suggest actions to perform in case of some specific events. Classes and properties of the ontology are included into a knowledge base, that grows dynamically with its use. A prototypal tool and a web application version have been implemented as an interface to the database, and to support non-expert users in the restoration process

Surface analysis and visualization from multi-light image collections

Multi-Light Image Collections (MLICs) are stacks of photos of a scene acquired with a fixed viewpoint and a varying surface illumination that provides large amounts of visual and geometric information. Over the last decades, a wide variety of methods have been devised to extract information from MLICs and have shown its use in different application domains to support daily activities. In this thesis, we present methods that leverage a MLICs for surface analysis and visualization. First, we provide background information: acquisition setup, light calibration and application areas where MLICs have been successfully used for the research of daily analysis work. Following, we discuss the use of MLIC for surface visualization and analysis and available tools used to support the analysis. Here, we discuss methods that strive to support the direct exploration of the captured MLIC, methods that generate relightable models from MLIC, non-photorealistic visualization methods that rely on MLIC, methods that estimate normal map from MLIC and we point out visualization tools used to do MLIC analysis. In chapter 3 we propose novel benchmark datasets (RealRTI, SynthRTI and SynthPS) that can be used to evaluate algorithms that rely on MLIC and discusses available benchmark for validation of photometric algorithms that can be also used to validate other MLIC-based algorithms. In chapter 4, we evaluate the performance of different photometric stereo algorithms using SynthPS for cultural heritage applications. RealRTI and SynthRTI have been used to evaluate the performance of (Neural)RTI method. Then, in chapter 5, we present a neural network-based RTI method, aka NeuralRTI, a framework for pixel-based encoding and relighting of RTI data. In this method using a simple autoencoder architecture, we show that it is possible to obtain a highly compressed representation that better preserves the original information and provides increased quality of virtual images relighted from novel directions, particularly in the case of challenging glossy materials. Finally, in chapter 6, we present a method for the detection of crack on the surface of paintings from multi-light image acquisitions and that can be used as well on single images and conclude our presentation

Innovative Techniques for Digitizing and Restoring Deteriorated Historical Documents

Recent large-scale document digitization initiatives have created new modes of access to modern library collections with the development of new hardware and software technologies. Most commonly, these digitization projects focus on accurately scanning bound texts, some reaching an efficiency of more than one million volumes per year. While vast digital collections are changing the way users access texts, current scanning paradigms can not handle many non-standard materials. Documentation forms such as manuscripts, scrolls, codices, deteriorated film, epigraphy, and rock art all hold a wealth of human knowledge in physical forms not accessible by standard book scanning technologies. This great omission motivates the development of new technology, presented by this thesis, that is not-only effective with deteriorated bound works, damaged manuscripts, and disintegrating photonegatives but also easily utilized by non-technical staff. First, a novel point light source calibration technique is presented that can be performed by library staff. Then, a photometric correction technique which uses known illumination and surface properties to remove shading distortions in deteriorated document images can be automatically applied. To complete the restoration process, a geometric correction is applied. Also unique to this work is the development of an image-based uncalibrated document scanner that utilizes the transmissivity of document substrates. This scanner extracts intrinsic document color information from one or both sides of a document. Simultaneously, the document shape is estimated to obtain distortion information. Lastly, this thesis provides a restoration framework for damaged photographic negatives that corrects photometric and geometric distortions. Current restoration techniques for the discussed form of negatives require physical manipulation to the photograph. The novel acquisition and restoration system presented here provides the first known solution to digitize and restore deteriorated photographic negatives without damaging the original negative in any way. This thesis work develops new methods of document scanning and restoration suitable for wide-scale deployment. By creating easy to access technologies, library staff can implement their own scanning initiatives and large-scale scanning projects can expand their current document-sets

Artificial intelligence for art investigation: Meeting the challenge of separating x-ray images of the Ghent Altarpiece

X-ray images of polyptych wings, or other artworks painted on both sides of their support, contain in one image content from both paintings, making them difficult for experts to “read.” To improve the utility of these x-ray images in studying these artworks, it is desirable to separate the content into two images, each pertaining to only one side. This is a difficult task for which previous approaches have been only partially successful. Deep neural network algorithms have recently achieved remarkable progress in a wide range of image analysis and other challenging tasks. We, therefore, propose a new self-supervised approach to this x-ray separation, leveraging an available convolutional neural network architecture; results obtained for details from the Adam and Eve panels of the Ghent Altarpiece spectacularly improve on previous attempts

Book of short Abstracts of the 11th International Symposium on Digital Earth

The Booklet is a collection of accepted short abstracts of the ISDE11 Symposium

Victorian Splendor: Analysis of the Late 19\u3csup\u3eth\u3c/sup\u3e Century Decorative Ceiling at Ebenezer Maxwell Mansion in Germantown, Pennsylvania

The decorative ceiling in the Stevenson Bedroom of the Ebenezer Maxwell Mansion in Philadelphia is one of the most outstanding examples of post-Centennial ornamental designs. The exotic, stylized, geometric pattern of the ceiling illustrates ideals set forth during the Centennial International Exhibition, held in Philadelphia in 1876, and emphasizes Victorians’ predisposition to live à la mode. However, as a result of harsh treatment conducted in the 1970’s and ‘80s and damaging environmental conditions, the ceiling design only partially remains today. This thesis considers an approach for interpreting decorative paintings where the original fabric is altered or missing. It argues that, in the absence of material evidence, an accurate estimation of decorative painting can be achieved by consulting a wide range of sources. Recommendations provided in this thesis incorporate raw data to create an authentic representation of a late 19th century interior, contributing to the historic interpretation of the site

A technical examination and discussion of the conservation decision-making process using Anton van Wouw’s Cattle Grazing near Pretoria Zoo (ca. 1896) as case study

Dissertation (MSocSci (Tangible Heritage Conservation))--University of Pretoria, 2022.The study aims to examine, discuss and develop a feasible treatment proposal for a damaged oil on canvas landscape Cattle Grazing near Pretoria Zoo that was completed around 1896. The painting is by Dutch-born South African artist Anton van Wouw (1862-1945) who is predominantly known as a sculptor. Therefore, the research aims to position the artist in a new light – that of a painter – since very little of his painting oeuvre has been documented or studied. The painting chosen for the case study was extensively damaged in the past, including storage in a folded state and has undergone several treatments in the past, including marouflage, consolidation and infilling; yet the treatment remains incomplete. The research proceeds by thoroughly documenting the painting using a variety of historical, visual and analytical techniques including technical photography and X-Ray Fluorescence spectroscopy, which are widespread in heritage conservation practices because of their non-invasive and non-destructive nature. The information obtained from these investigations sheds light on van Wouw as a painter, his technique and material use, for which there is currently no data. In addition, the analytical research sets the foundation for discussing the treatment decision-making process that ensues. The treatment proposal employs contemporary conservation ethics as guidance to ensure the integrity of the painting’s history and meaning remains intact, and based on consultations with the painting’s custodian discusses its intended future use and potential avenues for treatment.Andrew W. Mellon FoundationMSocSci (Tangible Heritage Conservation

EG-ICE 2021 Workshop on Intelligent Computing in Engineering

The 28th EG-ICE International Workshop 2021 brings together international experts working at the interface between advanced computing and modern engineering challenges. Many engineering tasks require open-world resolutions to support multi-actor collaboration, coping with approximate models, providing effective engineer-computer interaction, search in multi-dimensional solution spaces, accommodating uncertainty, including specialist domain knowledge, performing sensor-data interpretation and dealing with incomplete knowledge. While results from computer science provide much initial support for resolution, adaptation is unavoidable and most importantly, feedback from addressing engineering challenges drives fundamental computer-science research. Competence and knowledge transfer goes both ways