Image segmentation applied to the investigation of craquelure domains in paintings

Old paintings are generally characterized by the presence of cracks patterns, formed during the drying process. This network of cracks, known as craquelure, represents a key feature for the authentication of artworks and the discovery of forgery. In this work, an image segmentation approach is used for a quantitative study of cracks patterns in paintings. We will show how the size distribution and orientation of the craquelure domains can be evaluated using this technique

An Integrated Content and Metadata based Retrieval System for Art

In this paper we describe aspects of the Artiste project to develop a distributed content and metadata based analysis, retrieval and navigation system for a number of major European Museums. In particular, after a brief overview of the complete system, we describe the design and evaluation of some of the image analysis algorithms developed to meet the specific requirements of the users from the museums. These include a method for retrievals based on sub images, retrievals based on very low quality images and retrieval using craquelure type

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 system for the investigation of cracks

This work aims to deal with the problem of identifying, analysing, and classifying cracks in figurative works. The recent, considerable progress made in techniques for processing visual information has broadened the number of scientific applications in which the display and graphic processing of data play a fundamental role. Cracks consist of many elements; distinguishing and studying them has made it possible to develop a classification that in some cases can also be used as tool to verify a work's authenticity. RESTART, the system presented here, is deemed suitable for use in numerous and varied settings, such as teaching, conservation, study and research. It is able to investigate, study, research and 'restore' the digital, in accordance with the criteria dictated by knowledge. Also of considerable interest is the investigation of a crack based on such characteristics as origin and pathology, and the possibility of analysing the cracks in a fresco. The use of RESTART for such case examples is investigated and proposed

The extraction and classification of craquelure patterns for geographical analysis of fine art painting

Craquelure represents the unique crack formations that form on a material with age. This thesis is specifically concerned with the craquelure patterns found on historical art paintings. Although the significance of craquelure has been noted for over 300 years, recent research has shown that these patterns are related to the materials and methods employed by the artist and that these clues may assist in the task of attribution. It has been shown that different art paintings constructed from the same geographical location exhibit similar craquelure formation patterns. With the intention of alleviating expertise on the subject of craquelure, the development of a framework for the geographical analysis of craquelure patterns has been attempted in literature. This thesis seeks to expand on these results with the intention of increasing the accuracy rate in the classification of craquelure to their corresponding geographical origins. Through the use of mathematical morphology and various image processing techniques, craquelure images were converted to binary images. Specific features were then extracted from the binary image and used in the classification process. Several different classifiers were tested and compared in this thesis

Structuration et défauts de surface et de volume lors du séchage de suspensions colloïdales

Controlling the production of colloidal suspension films by evaporation is still, nowadays, atruly scientific obstacle for materials development. The drying of colloidal suspensions leads often tosurface and volume defects in the film. When the particles are soft, films are continuous but haveseveral folding surface defects. However, when the particles are hard (glassy latex, silica,...), the filmtends to crack and to be delaminated. These defects are often associated with residual stresses in thegel at the end of drying, due to the capillary pressure caused by the water menisci deformation at thefilm surface. Nevertheless, neither the size scale where constraint acts nor the relation between stressand cracking time were known.In this thesis we present the study of cracks morphology observed in films of differentcolloidal suspension mixtures obtained by a drying process. These mixtures are composed of hard(polystyrene crosslinked PBMA) and soft (PBA and PBMA) particles. The nanometric structure ofthese mixtures is obtained through neutron scattering and turbidity studies. We have mixtures withdifferent structures and different states of dispersion. While some mixtures contain dispersed particlesat a nanoscale, with an order of magnitude same as the particles size - 50 nm, some others containaggregated particles. The study of cracks morphology is performed on sessile drops by drying at thefree surface. Periodic radial cracks are observed during drying. We also observe that cracks periodincrease with the increment of soft particles fraction and temperature, but keeping constant itsperiodicity. We have demonstrated that the ratio: crack period between film thickness, i.e. λ/h, is theonly parameter that describes perfectly cracks morphology for a drying process at a free surface. Wealso demonstrated that this relation (λ/h) couldn’t decrease below 2 even in the case of glassy particles.Drying process induces high residual stresses in the gel, allowing to some fibers located between twocracks to delaminate radially. This delamination phenomenon fades with dissipation constraints. Wehave also established that the Russel’s mechanical model does not describe the period of cracks nearthe critical stress. Therefore, in this work we propose another model able to characterize theperiodicity of the cracks. We noticed that the properties of the substrate did not affect cracksmorphology. The evaporation rate changes the morphology of cracks, which in the case of a quickdrying it is possible to obtain unidirectional long loose fibers. However, for a slow drying, we arewitnessing the formation of not protruding cracks with the apparition of secondary transverse cracks.La maîtrise de la fabrication de films de suspension colloïdale par évaporation constitueencore à ce jour, un véritable verrou scientifique pour l’élaboration des matériaux. Le séchage desuspensions colloïdales entraine souvent des défauts de surface et de volume dans le film. Lorsque lesparticules sont molles, les films sont continus mais présentent des défauts de plissement de surface.Lorsque les particules sont dures (latex vitreux, silice..), le film se fissure et se délamine. Ces défautssont souvent liés aux contraintes résiduelles dans le gel à la fin du séchage qui sont dues à la pressioncapillaire causée par la déformation des ménisques d’eau à la surface des films. Par contre on neconnait pas encore l’échelle de taille où agit la contrainte ni la relation entre la contrainte et la périodedes craquelures.Dans ce travail de thèse, nous étudions la morphologie des craquelures dans des films dedivers mélanges de suspensions colloïdales, élaborés par séchage. Ces mélanges sont composés departicules dures (polystyrène et PBMA réticulés) et molles (PBA et PBMA). La structurenanométrique de ces mélanges est caractérisée par diffusion de neutron et par turbidité. Nousdisposons de mélanges avec diverses structures et divers états de dispersion. Certains mélangescontiennent des particules dispersées à l’échelle nanométrique (l’ordre de grandeur est celle de la tailledes particules - 50 nm) alors que d’autres contiennent des particules agrégées. L’étude de lamorphologie des craquelures est réalisée sur des gouttes sessiles avec séchage à la surface libre. Descraquelures radiales périodiques sont observées lors du séchage. Nous observons que la période descraquelures augmente avec l’augmentation de la fraction en particules molles et de la température maistoute en conservent la périodicité. Nous avons mis en évidence que le rapport : période des craqueluressur l’épaisseur des films λ/h est le seul paramètre qui décrit parfaitement la morphologie descraquelures pour un séchage au niveau d’une surface libre. Nous avons aussi démontré que ce rapportλ/h ne peut pas descendre au-dessous de 2 même dans le cas de particules vitreuses. Le séchage induitde fortes contraintes résiduelles dans le gel qui permettent à certaines fibres situées entre deuxcraquelures de délaminer radialement. Ce phénomène de délamination s’estompe avec la dissipationdes contraintes. Nous avons démontré que le modèle mécanique de Russel ne permet pas de décrire lapériode de craquelures loin de la contrainte critique. Nous proposons ainsi dans le cadre de notretravail, un autre modèle plus à même à caractériser la périodicité de ces craquelures. Nous avonsremarqué que les propriétés du substrat n'ont aucune incidence sur la morphologie des craquelures. Letaux d'évaporation modifie la morphologie des craquelures, où dans le cas d’un séchage rapide, onobtient des fibres décollées longues unidirectionnelles tandis que pour le cas d’un séchage lent, onassiste à la formation de craquelures non décollées avec apparition de craquelures secondairestransverses