Applications of Reflectance Transformation Imaging (RTI) for Books and Objects on Paper

Grzelec, Małgorzata; Łojewski, Tomasz

doi:10.1080/18680860.2023.2170306

Cited by 3 publications

(1 citation statement)

References 17 publications

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“…RTI was introduced by Malzbender et al [1] in 2001. This is mainly used as a nondestructive and in situ device in cultural heritage (paintings [2], coins [3], rocks [4], archaeology [5,6], libraries [7], etc.). The relevance of the RTI use in situ was especially highlighted by Selmo et al, who developed an RTI instrument for an underwater use [8].…”

Section: Introductionmentioning

confidence: 99%

A New RTI Portable Instrument for Surface Morphological Characterization

Lemesle,

Bigerelle

2024

Hardware

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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.

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