A Methodological Approach for Multi-Temporal Tracking of Silver Tarnishing

Σιάτου, Αμαλία; Castro, Yuly; Nurit, Marvin; Chatoux, Hermine; Goïc, Gaëtan Le; Degrigny, Christian; Brambilla, Luca; Mansouri, Alamin

doi:10.1145/3552464.3555686

Cited by 3 publications

(3 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This type of corrosion is known to form a corrosion layer on the entire metal surface detected due to the change in color ranging from yellowish, for thin layers, to dark blue-black, for thicker ones [23,24]. For the experimental part, flat test specimens (coupons) were prepared from pure silver (Ag 99.9%) and were then artificially tarnished using the protocol described in [17]. Three different textures were evaluated matt (diffusive), satin (anisotropic), and mirror (specular) (fig.…”

Section: Case Studymentioning

confidence: 99%

“…The application of raw RTI data analysis based on features for the conservation documentation of CH metal surfaces was exploited by [16]. Furthermore, have explored the feasibility of monitoring corrosion based on these developments with application on silver tarnishing for assessing surface changes and determining the degree of corrosion [17]. The evaluation based on features reveals surface information related to condition assessment and semi-quantitative analysis of the resulting changes while providing spatial information in automated cartographies.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Appearance segmentation and documentation applied to cultural heritage surfaces

Saha¹,

Σιάτου²,

Degrigny³

et al. 2023

View full text Add to dashboard Cite

This paper describes the application of a novel supervised segmentation technique used for conservation documentation based on visible appearance changes of Cultural Heritage (CH) metal surfaces. The technique employs a linear discriminant analysis model to classify Reflectance Transformation Imaging (RTI) reconstruction coefficients. The Hemispherical Harmonics (HSH) reconstruction coefficients for each pixel are first calculated and then normalized. This normalization enhances the robustness and invariance of the application, making it possible to apply it for documenting different surfaces at different time intervals. This paper presents three cases related to surface appearance changes due to corrosion that provokes low or high topographic changes. Tarnishing of silver and filiform corrosion on steel are examined. For each case study, a supervised data set is constructed, teaching the algorithm to recognize as distinct a specified appearance characteristic (such as corrosion, metal, etc.) by comparing it to the reconstruction coefficients of each pixel through Linear Discriminant Analysis (LDA). A simplified color map visualizes the segmented information. The calculated results are afterward verified by visible inspection from conservation-restoration experts. The method can segment surfaces with changes in micro-geometry, creating accurate cartographies of the object's condition. However, limitations are met on surfaces with minimal topography and high specularity.

show abstract

Section: Case Studymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Appearance segmentation and documentation applied to cultural heritage surfaces

Saha¹,

Σιάτου²,

Degrigny³

et al. 2023

View full text Add to dashboard Cite

show abstract

“…Recent studies were performed in mechanics in order to characterize composite material damage [9], to control visual quality (defects on metallic surfaces [10] and silver tarnishing over time [11]), and to analyze material fracture, failure or corrosion [12][13][14].…”

Section: Introductionmentioning

confidence: 99%

A New RTI Portable Instrument for Surface Morphological Characterization

Lemesle,

Bigerelle

2024

Hardware

View full text Add to dashboard Cite

A new instrument using reflectance transformation imaging (RTI), named MorphoLight, has been developed for surface characterization. This instrument is designed to be adjustable to surfaces, ergonomic, and uses a combination of high-resolution imaging functions, i.e., focus stacking (FS) and high dynamic range (HDR), to improve the image quality. A topographical analysis method is proposed with the instrument. This method is an improvement of the surface gradient characterization by light reflectance (SGCLR) method. This aims to analyze slope/curvature maps, traditionally studied in RTI, but also to find the most relevant lighting position and 3D surface parameter which highlight morphological signatures on surfaces and/or discriminate surfaces. RTI measurements and analyses are performed on two zones, sky and sea, of a naval painting which have the same color palette but different painting strokes. From the statistical analysis using bootstrapping and analysis of variance (ANOVA), it is highlighted that the high-resolution images (stacked and tonemapped from HDR images) improve the image quality and make it possible to better see a difference between both painting zones. This difference is highlighted by the fractal dimension for a lighting position (θ, φ) = (30°, 225°); the fractal dimension of the sea part is higher because of the presence of larger brushstrokes and painting heaps.

show abstract