Examination and Analysis Techniques
Automated thread counting: Thread count and weave information were determined by Thread Count Automation Project software.[1]1
High-resolution reflected- and transmitted-infrared imaging: Sinar rePro camera with 86H back (Heliopan RG830 [87c] cut filter) with Broncolor flash radiation sources.2
High-resolution reflected-light, transmitted visible-light, and raking-light imaging: Sinar rePro camera with 86H back (B+W Infrared 093 filter) with Broncolor flash light sources.3
High-resolution ultraviolet-induced luminescence imaging: Sinar rePro camera with 86H back (B+W Infrared 093 filter, PECA 918 UV/IR interference cut filter) with UV Systems Triplebright ultraviolet radiation sources.4
Hyperspectral imaging (HSI): Resonon Pika II pushbroom in the 400–1000 nm range, calibrated using a 99% Spectralon reflectance standard, with tungsten-halogen radiation sources.5
Image registration software: Overlay images registered using a novel, image-based algorithm developed by Damon M. Conover (GW), John K. Delaney (GW, NGA), and Murray H. Loew (GW) of the School of Engineering and Applied Science, the George Washington University, and the National Gallery of Art, Washington, DC.[2]6
Infrared reflectography: Goodrich/Sensors Unlimited SU640SDV-1.7RT (0.9–1.7 µm) with H filter (1.1–1.4 µm) and J filter (1.5–1.7 µm).7
In-situ Fourier transform infrared spectroscopy in reflectance (reflected FTIR): A Bruker Alpha spectrometer, equipped with a specular reflectance head, was used. Spectra were captured in the 365–7000 cm-1 range with a 4 cm-1 resolution.8
Microscopy and photomicrographs: Sample and cross-sectional analysis using Zeiss Axioplan2 Research Microscope equipped with reflected light/UV fluorescence and a Leica DMC 4500 digital camera. (Types of illumination used: darkfield, brightfield, differential interference contrast [DIC], and UV fluorescence.) In-situ photomicrographs with Wild Heerbrugg M7A StereoZoom Microscope fitted with Olympus DP71 microscope digital camera, Leica M125 stereomicroscope 8-100×, and a MC170 HD camera or Hirox RX-100 digital microscope equipped with a multi-illumination turret zoom lens (20–2500×).9
Polarized light microscopy (PLM): Zeiss Universal Research Microscope.10
Scanning electron microscopy/energy-dispersive X-ray spectroscopy (SEM/EDX): Cross sections were analyzed with a Hitachi S-3400N-II VPSEM with an Oxford energy dispersive spectrometer (EDX) and a Hitachi solid-state BSE detector. Analysis was performed at the Atomic and Nanoscale Characterization Experimental (NUANCE) Center, Electron Probe Instrumentation Center (EPIC) facility, Northwestern University, Evanston, Illinois.11
X-radiography: Westinghouse X-ray unit, films scanned on Epson Expressions 10000XL flatbed scanner.12
X-ray fluorescence spectroscopy (XRF): Several spots on the artworks were analyzed in situ with a Bruker ArtTAX micro-XRF with molybdenum tube or a Bruker TRACeR III-V with rhodium tube. Scanning macro X-ray fluorescence (MA-XRF) was carried out using (1) a custom-made instrument, designed and constructed at Northwestern University (maps were acquired at 40 kV, 100 μA, 1mm step size and an integration time of 0.1 s);[3] and (2) an ELIO spectrometer, manufactured by XG-Lab, at 40 kV, 30 μA, 1 mm step size and an integration time of 1 s.
13
- See Don H. Johnson et al., “A Thread Counting Algorithm for Art Forensics,” in 2009 IEEE Thirteenth Digital Signal Processing and Fifth IEEE Signal Processing Education Workshop (Institute of Electrical and Electronics Engineers, 2009), 679–84, https://doi.org/10.1109/DSP.2009.4786009.
- See Damon M. Conover et al., “Towards Automatic Registration of Technical Images of Works of Art,” in Computer Vision and Image Analysis of Art II, Proceedings of SPIE—The International Society for Optical Engineering 7869 (SPIE, 2011), 7869 0C; https://doi.org/10.1117/12.872634.
- E. Pouyet et al., “Development of a Highly Mobile and Versatile Large MA-XRF Scanner for In-Situ Analyses of Painted Work of Arts,” X-Ray Spectrometry 50, no. 4 (2020): 263–71.
“Examination and Analysis Techniques,” in Cezanne Paintings and Watercolors at the Art Institute of Chicago, ed. Gloria Groom and Kim Muir (Art Institute of Chicago, 2026), https://doi.org/10.53269/9780865593251/22. © 2026 by The Art Institute of Chicago. This work is licensed under a CC BY-NC 4.0 license: creativecommons.org/licenses/by-nc/4.0/.
