Characterizing pigments with hyperspectral imaging variable false-color composites

Hayem-Ghez, Anita; Ravaud, Élisabeth; Boust, Clotilde; Bastian, Gilles; Menu, Michel; Brodie–Linder, Nancy

doi:10.1007/s00339-015-9458-8

Cited by 32 publications

(21 citation statements)

References 7 publications

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“…The results were compared with those from spectral angle mapping and principle component analysis algorithms in ENVI. Following the methodology in Hayem-Ghez et al [13], hyperspectral pseudo-colour images of red and blue watercolour pigment standards from the samples discussed above were rendered by identifying areas of their Vis/VNIR reflectance spectra showing the most significant differences. These were then compared to the hyperspectral images of two paintings by Bauer rendered to the same three wavelength bands: 593, 629 and 859 nm.…”

Section: Hyperspectral Mapping and Pseudo-colour Composites Of Fauna mentioning

confidence: 99%

“…Previous studies have used Raman spectroscopy, XRF, FORS and imaging spectroscopy for the non-invasive study of watercolour pigments in both manuscripts and paintings on paper [7][8][9][10][11][12][13]. Although more interventive technologies such as Surface Enhanced Raman Spectroscopy (SERS) have yielded better results with watercolour pigments, [14] these require either sampling, or direct contact with the surface of the object, something that is often not permitted in heritage collections.…”

Section: Introductionmentioning

confidence: 99%

“…For artists' pigments, the value of hyperspectral scanning is to provide a digital image of the entire surface of an object, from which multiple analytical approaches can be taken (pseudocolour mapping, principle component analysis and spectral angle mapping etc.). Delaney and others [11][12][13] have demonstrated the value of using both fibre optic reflectance spectroscopy (FORS) together with imaging spectroscopy and hyper/multispectral imaging to visualise and map the location of pigments in objects as diverse as paintings by Picasso and medieval illuminated manuscripts. Hayem-Ghez et al [13] have also successfully demonstrated the validity of using hyperspectral pseudo-colour composites to differentiate between visually similar pigments.…”

Section: Introductionmentioning

confidence: 99%

“…Delaney and others [11][12][13] have demonstrated the value of using both fibre optic reflectance spectroscopy (FORS) together with imaging spectroscopy and hyper/multispectral imaging to visualise and map the location of pigments in objects as diverse as paintings by Picasso and medieval illuminated manuscripts. Hayem-Ghez et al [13] have also successfully demonstrated the validity of using hyperspectral pseudo-colour composites to differentiate between visually similar pigments. Therefore, the combination of portable Raman spectroscopy, FORS and XRF analysis together with Hyperspectral imaging can be considered a valuable and non-invasive system for the identification of historic watercolour pigments.…”

Section: Introductionmentioning

confidence: 99%

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Identifying eighteenth century pigments at the Bodleian library using in situ Raman spectroscopy, XRF and hyperspectral imaging

et al. 2017

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There are multiple challenges in analysing pigments in historic watercolour paintings on paper, and typically noninvasive, in situ methods are required. Recent developments in portable analytical instrumentation have made this more accessible to heritage institutions, but many commercial systems are not optimised for the specific requirements of manuscripts and works on paper. This paper describes the successful use of Raman spectroscopy, X-ray fluorescence spectroscopy (XRF) and hyperspectral imaging to identify and map watercolour pigments used by the eighteenth century botanical illustrator, Ferdinand Bauer, and demystify the unusual colour code system found in his sketches. The value, delicate nature and large size of these paintings necessitated the use of using in situ, noncontact methods of analysis. A portable, bespoke Raman spectrometer specifically designed for analysing pigments from works on paper was used together with a bespoke portable Fibre optic reflectance spectrometer, portable X-Ray Fluorescence spectrometer and a hyperspectral imaging sensor. The results demonstrate that although there is a significant compromise between achieving good Raman spectroscopic results from artists' pigments and using sufficiently low laser power densities so as not to cause damage to the pigments, good results could be obtained with this portable system, particularly when combined with XRF, fibre optic reflectance spectroscopy (FORS) and hyperspectral imaging. Eight pigments were identified unequivocally from 125 watercolour paintings analysed, suggesting that Bauer used a more traditional and more limited palette than previously considered, and that his palette changed significantly in his later paintings. Similar pigments identified by the authors on colour chart that was discovered in 1999 in Madrid and attributed to Bauer, add weight to the attribution of this chart to Bauer. The data provides a much deeper insight into Bauer's colour annotations, and how he was able to achieve such an impressive degree of colour fidelity in his work.

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Section: Hyperspectral Mapping and Pseudo-colour Composites Of Fauna mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Identifying eighteenth century pigments at the Bodleian library using in situ Raman spectroscopy, XRF and hyperspectral imaging

et al. 2017

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“…The identification of materials in works of art via HSI can be done by comparing the reflectance spectra for the relevant pixel to those of a reference database or by the creation of false colour images from the hyperspectral data as per Haymen-Ghez et al [49]. Such false colour composite images have recently been successfully used to aid the identification of watercolour pigments in eighteenth century botanical illustrations by Ferdinand Bauer [50], this study however focusses on the former identification method.…”

Section: Hyperspectral Imagingmentioning

confidence: 99%

Comparing the effectiveness of hyperspectral imaging and Raman spectroscopy: a case study on Armenian manuscripts

et al. 2018

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There is great practical and scholarly interest in the identification of pigments in works of art. This paper compares the effectiveness of the widely used Raman Spectroscopy (RS), with hyperspectral imaging (HSI), a reflectance imaging technique, to evaluate the reliability of HSI for the identification of pigments in historic works of art and to ascertain if there are any benefits from using HSI or a combination of both. We undertook a case study based on six Armenian illuminated manuscripts (eleventh-eighteenth centuries CE) in the Bodleian Library, University of Oxford. RS, and HSI (380-1000 nm) were both used to analyse the same 10 folios, with the data then used to test the accuracy and efficiency of HSI against the known results from RS using reflectance spectra reference databases compiled by us for the project. HSI over the wavelength range 380-1000 nm agreed with RS at best 93% of the time, and performance was enhanced using the SFF algorithm and by using a database with many similarities to the articles under analysis. HSI is significantly quicker at scanning large areas, and can be used alongside RS to identify and map large areas of pigment more efficiently than RS alone. HSI therefore has potential for improving the speed of pigment identification across manuscript folios and artwork but must be used in conjunction with a technique such as RS.

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A Portable Set up for Hyperspectral Imaging of Stained-Glass Panels

Babini

George

Lombardo

et al. 2022

Communications in Computer and Information Science

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Characterizing pigments with hyperspectral imaging variable false-color composites

Cited by 32 publications

References 7 publications

Identifying eighteenth century pigments at the Bodleian library using in situ Raman spectroscopy, XRF and hyperspectral imaging

Identifying eighteenth century pigments at the Bodleian library using in situ Raman spectroscopy, XRF and hyperspectral imaging

Comparing the effectiveness of hyperspectral imaging and Raman spectroscopy: a case study on Armenian manuscripts

A Portable Set up for Hyperspectral Imaging of Stained-Glass Panels

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