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Thursday, May 16 • 3:00pm - 3:30pm
(Imaging Tools/Techniques/& Tactics) Materials Characterization with Multiband Reflectance Image Subtraction At the Brooklyn Museum: A New Tool for the Multiband Imaging Kit

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In pursuit of accessible tools for non-invasive examination, Brooklyn Museum (BKM) conservators experimented with using multiband reflectance image subtraction (MBRIS) to characterize materials in the collection. This imaging technique can visualize and localize materials that have a pronounced difference in reflectance across defined spectral bands, producing a map of an object’s surface. As pioneered by Webb et al., MBRIS utilizes a camera that captures monochromatic images and combines one near infrared image and one visible light image in digital post-processing. The technique was adapted for multiband imaging equipment already in use at BKM. As few references to MBRIS exist in the literature, BKM conservators not only evaluated the information gained from its application, but also investigated the technique itself, refining variables in image capture and processing to optimize results and create representative images. An overview of the broad applications of the MBRIS protocols developed at BKM will be presented in addition to a discussion of the challenges associated with equipment set up and image processing. Prompted by the exhibition “Infinite Blue,” MBRIS has been used at BKM to localize the presence of indigo dye on both Egyptian and Andean textiles, indigo-containing paints on Egyptian cartonnage, and indigo-containing Maya blue pigment on ancient figurines, as well as to characterize lapis lazuli components of Afghani, Chinese, Russian, and Egyptian objects. MBRIS has also helped distinguish indigo from Prussian blue on Japanese woodblock prints and visualize areas of retouching carried out on a Colonial American portrait. As part of the Getty initiative Ancient Panel Paintings: Examination, Analysis and Research (APPEAR), BKM conservators conducted a focused study on the use of indigo-containing paints in six Romano-Egyptian funerary portraits, which provided the opportunity to refine the BKM imaging protocols. The BKM APPEAR study assessed MBRIS in the context of analytical results obtained through fiber optics reflectance spectroscopy, Raman spectroscopy, and X-ray fluorescence spectroscopy, as well as in concert with X-radiographs and a broader suite of multiband images. The imaging guidelines established during the APPEAR project explicated and reduced inconsistencies observed in initial MBRIS images arising from variations in the relative exposures of the near infrared and visible light captures. Further investigation into MBRIS processing carried out using softwares such as Adobe Photoshop, ImageJ, and GIMP, demonstrated that exposure adjustment post-capture can yield unrepresentative results and that multiple functions employed during post-processing affect the final MBRIS output. BKM conservators are also experimenting with a new approach to generating MBRIS images that would preserve information about both the magnitude and the sign of the values calculated in post-processing. Preliminary imaging of known pigment samples in the BKM reference collection indicates that MBRIS could be used to characterize additional colorants or media on cultural heritage objects. The overall success of this MBRIS imaging project suggests the potential to develop protocols involving different combinations of filters and light sources for the characterization of other materials that have pronounced changes in reflectance across the ultraviolet, visible, and infrared spectral regions.

Speakers
avatar for Dawn Lohnas Kriss

Dawn Lohnas Kriss

Conservator, Dawn Kriss LLC
Dawn Kriss LLC provides objects conservation, imaging, and consultation services. Prior to entering into private practice, Dawn Lohnas Kriss held positions at the Brooklyn Museum, the Metropolitan Museum of Art, the American Museum of Natural History, the J. Paul Getty Villa Museum... Read More →

Co-Author
avatar for Elyse Driscoll

Elyse Driscoll

Conservator, Brooklyn Museum
Elyse Driscoll is the Assistant Paper Conservator at the Brooklyn Museum. She holds a BFA in Drawing from Pratt Institute and an MA and CAS in Art Conservation with a specialization in works on paper from SUNY Buffalo State. Her training included internships at the Morgan Library... Read More →
avatar for Jessica Ford

Jessica Ford

Paintings Conservator, Amann + Estabrook Conservation Associates
Jessica Ford is a Paintings Conservator at Amann + Estabrook Conservation Associates. She earned a Master of Science in Art Conservation from the Winterthur/University of Delaware Program in Art Conservation and has previously held positions at the Brooklyn Museum, Smithsonian American... Read More →
avatar for Lauren Bradley

Lauren Bradley

Associate Conservator of Paintings, Brooklyn Museum
Lauren Bradley is the Associate Conservator of Paintings at the Brooklyn Museum. She earned an M.S. from the Winterthur/University of Delaware Program in Art Conservation and has held positions at the Kimbell Art Museum, the J. Paul Getty Museum, the Mauritshuis Royal Picture Gallery... Read More →
avatar for Victoria Schussler

Victoria Schussler

Project Objects Conservator, Brooklyn Museum
Victoria Schussler is a Project Objects Conservator at the Brooklyn Museum. Victoria received a Bachelor of Arts in Biology from Yale University and Master of Science in Art Conservation from the Winterthur/University of Delaware Program in Art Conservation. Victoria has held positions... Read More →


Thursday May 16, 2019 3:00pm - 3:30pm EDT
Earth Ballroom A Earth Convention Center, Mohegan Sun
  General Session, Imaging Tools/Techniques/& Tactics
  • Ticketed Included in Main Registration
  • Authors in Publication Order Victoria Schussler, Dawn Kriss, Lauren Bradley, Jessica Ford, Elyse Driscoll
  • Abstract ID 19088
  • Tags Digital Imaging,Multiband Imaging,Multispectral Imaging,Photography,Blue,Indigo,Colorant Characterization,MBI,MSI,Low-Tech