Multi-modal dictionary learning for image separation with application in art investigation

In support of art investigation, we propose a new source separation method that unmixes a single X-ray scan acquired from double-sided paintings. In this problem, the X-ray signals to be separated have similar morphological characteristics, which brings previous source separation methods to their limits. Our solution is to use photographs taken from the front and back-side of the panel to drive the separation process. The crux of our approach relies on the coupling of the two imaging modalities (photographs and X-rays) using a novel coupled dictionary learning framework able to capture both common and disparate features across the modalities using parsimonious representations; the common component models features shared by the multi-modal images, whereas the innovation component captures modality-specific information. As such, our model enables the formulation of appropriately regularized convex optimization procedures that lead to the accurate separation of the X-rays. Our dictionary learning framework can be tailored both to a single- and a multi-scale framework, with the latter leading to a significant performance improvement. Moreover, to improve further on the visual quality of the separated images, we propose to train coupled dictionaries that ignore certain parts of the painting corresponding to craquelure. Experimentation on synthetic and real data - taken from digital acquisition of the Ghent Altarpiece (1432) - confirms the superiority of our method against the state-of-the-art morphological component analysis technique that uses either fixed or trained dictionaries to perform image separation.Comment: submitted to IEEE Transactions on Images Processin

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

Image Separation with Side Information: A Connected Auto-Encoders Based Approach

X-radiography (X-ray imaging) is a widely used imaging technique in art investigation. It can provide information about the condition of a painting as well as insights into an artist’s techniques and working methods, often revealing hidden information invisible to the naked eye. X-radiograpy of double-sided paintings results in a mixed X-ray image and this paper deals with the problem of separating this mixed image. Using the visible color images (RGB images) from each side of the painting, we propose a new Neural Network architecture, based upon ’connected’ auto-encoders, designed to separate the mixed X-ray image into two simulated X-ray images corresponding to each side. This connected auto-encoders architecture is such that the encoders are based on convolutional learned iterative shrinkage thresholding algorithms (CLISTA) designed using algorithm unrolling techniques, whereas the decoders consist of simple linear convolutional layers; the encoders extract sparse codes from the visible image of the front and rear paintings and mixed X-ray image, whereas the decoders reproduce both the original RGB images and the mixed X-ray image. The learning algorithm operates in a totally self-supervised fashion without requiring a sample set that contains both the mixed X-ray images and the separated ones. The methodology was tested on images from the double-sided wing panels of the Ghent Altarpiece , painted in 1432 by the brothers Hubert and Jan van Eyck. These tests show that the proposed approach outperforms other state-of-the-art X-ray image separation methods for art investigation applications

At The Meadows - Fall 2011

https://scholar.smu.edu/atthemeadows/1000/thumbnail.jp

ANALYSIS AND CONSERVATION OF PORTRAIT OF A YOUNG MAN, FORMERLY ATTRIBUTED TO ÉDOUARD MANET

A painting that was formerly attributed to Édouard Manet, was researched, examined, and technically analyzed. Imaging techniques revealed a hidden inscription in the background that places the painting in Paris in the late 19th century. Scanning Macro-X-Ray Fluorescence Spectroscopy (MA-XRF), Optical Microscopy, Scanning Electron Microscopy-Energy Dispersive Spectroscopy SEM-EDS), and Fourier Transform Infrared Spectroscopy (FTIR) confirmed that no anachronistic pigments, media, or materials were used in the work. The painting was separated from its warped backing board and mounted to a new secondary support. Overpaint was removed to reveal the original inscription

A framework for surface metrology on Cultural Heritage objects based on scanning conoscopic holography

L'applicazione della metrologia di superficie e dell'analisi dimensionale allo studio dei beni culturali può rivelare importanti informazioni sull'oggetto e favorire l'integrazione di molteplici tecniche diagnostiche. Tuttavia, l'applicazione di queste discipline ai Beni Culturali richiede particolari requisiti e attenzioni. In questa tesi, presento i risultati dell'implementazione di diversi sistemi di misurazione della superficie basati sul principio della conoscopia olografica. I senori conoscopici sono strumenti capaci di misurare distanze con precisione micrometrica a scale diverse, accoppiati a slitte micrometriche possono essere utilizzati per acquisire scansioni areali dell'oggetto in esame. Per facilitare la loro applicazione alle opere d'arte ho sviluppato un extit{framework} per applicare la metrologia di superficie ai beni culturali. Il framework copre diversi aspetti del processo di analisi ed utilizzo dei dati e comprende la creazione di raccolte di campioni, le strategie per la scansione dell'oggetto, l'archiviazione e l'analisi dei dati ed eventualmente l'incertezza legata alla misura. Il extit{framework} mira a rendere più accessibile l'implementazione della metrologia di superficie e dei sistemi di scansione dell'analisi dimensionale per l'analisi dei beni culturali. I risultati raccolti su una varietà di materiali artistici (metalli, dipinti su tavola, tela, carta, pergamena e dipinti murali) mostrano come questi sistemi possano essere utilizzati per monitorare gli effetti delle procedure di pulitura, la stabilità dimensionale delle opere d'arte ed il loro invecchiamento.The application of surface metrology and dimensional analysis to the study of artworks can reveal important information on the object and aid the integration of multiple techniques. However, the application of these disciplines to Cultural Heritage objects necessitates particular care and requirements. In this dissertation, I present the results of the implementation of different systems, based on Conoscopic Holography range finders, for measuring the surface. Conoscopic holography range finders are viable instruments for measuring distances with micrometer accuracy at different scales, coupled with micrometric stages they can be used for acquiring areal scans of the object under investigation. To ease their application to artworks I built a framework for applying surface metrology to Cultural Heritage objects. The framework covers different aspects of the research workflow comprising the creation of samples collections, the strategies for scanning the object, the storing and the analysis of the data and eventually the uncertainty linked to the measurement. This framework aims to make more accessible the implementation of surface metrology and dimensional analysis scanning systems tailored to the analysis of Cultural Heritage objects. The results collected on a variety of artworks materials (metals, panels painting, canvas, paper, parchment and mural paintings) show how these systems can be used for monitoring the effects of cleaning procedures, the dimensional stability of the artworks and their ageing

A non-local dual-domain approach to cartoon and texture decomposition

International audienceThis paper addresses the problem of cartoon and texture decomposition. Microtextures being characterized by their power spectrum, we propose to extract cartoon and texture components from the information provided by the power spectrum of image patches. Thecontribution of texture to the spectrum of a patch is detected as statistically significant spectral components with respect to a nullhypothesis modeling the power spectrum of a non-textured patch. The null-hypothesis model is built upon a coarse cartoon representationobtained by a basic yet fast filtering algorithm of the literature. Hence the term ``dual domain'': the coarse decomposition is obtained in thespatial domain and is an input of the proposed spectral approach. The statistical model is also built upon the power spectrum of patches with similar textures across the image. The proposed approach therefore falls within the family of non-local methods. Experimental results are shown in various application areas, including canvas pattern removal in fine arts painting, or periodic noise removal in remote sensing imaging

Culture Warriors: Education and Awareness at the Inaugural National Indigenous Art Triennial, organized by National Gallery of Australia, 2007-2009

This thesis discusses the inaugural National Indigenous Art Triennial: Culture Warriors organized and hosted by the National Gallery of Australia and provides a critical analysis of the National Indigenous Art Triennial: Educational Resource that accompanied the exhibition. The aim of this discussion and analysis is to identify elements from the educational program at the National Gallery of Australia (NGA) that effectively increase knowledge and appreciation of Indigenous art at the Gallery. The premise behind my analysis consists of the possibility and feasibility of using similar educational programs in a Canadian context. Using an exploratory approach, this thesis brings attention to elements that could potentially be of benefit to the National Gallery of Canada (NGC) in the development of future educational programs associated with Indigenous Art exhibitions. It is well-known that, in the past, the NGC has been criticized for its exhibition, collecting, and dissemination practices with regards to Indigenous art. Having undergone considerable changes since the 1990’s, the NGC is beginning to look like a different institution especially with the establishment of an Indigenous Art Department in August 2007. One particular area criticized in the past about the NGC has been public access to and information about Indigenous art at the Gallery. As stated by Alfred Young Man, Department Head of Indian Fine Arts, at the First Nations University of Canada, in 2008; “There needs to be a better way for people who are looking for Aboriginal art at the National Gallery to find it, and learn about it.” Today, the NGC’s mandate seeks to “increase the knowledge, awareness and appreciation of Indigenous art in Canada and internationally.” With its Indigenous Art Department currently in a relative stage of infancy, it is a logical time to be looking at the educational tools being developed and implemented at similar institutions, such as the NGA, for ideas as to how the NGC can fulfill its present-day mandate

Legitimate landscapes: repositioning regional art production

This thesis employs art history and critical ethnography to examine contemporary art production in the South West of Western Australia. Responding to a paucity of publications and critique, and a claim the art scene is ‘folksy’ and ‘not up-to speed’ with metropolitan art scenes, I argue that ‘being regional’ is a legitimate position on its own terms and as part of a growing global tendency to recognises the validity of regional contexts and perspectives