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Research Publications

Knowledge disseminiation is a critical aspect of our research

Many past publications are available at the Art-Spectral Imaging site. Listed below are work for the current project, and moving forward from 2014.

Journal Articles

Geometry-Independent Target-Based Camera Colorimetric Characterization

Farhad Moghareh Abed, Roy S. Berns, Kenichiro Masaoka

The Saunderson equations were used to compensate for differences in illuminant geometry between imaging systems and reference spectrophotometers. J. Imaging Science Technology 57, 050503-1 – 15 (2013). download article

Wavelength-Dependent Spatial Correction and Spectral Calibration of a Liquid Crystal Tunable Filter System

Roy S. Berns, Brittany D. Cox, Farhad Moghareh Abed

A practical workflow was developed for the spectral calibration of a multispectral imaging system using liquid crystal tunable filter (LCTF) based . The workflow calibrated the system such the scale of spectral reflectance factor was transfered to the imaging system. The novel aspect of this research was a spatial correction accounting for the angular dependency of interference filters. Applied Optics, 54 3687-3693 (2015). download article

 

Conference Proceedings

Artist Paint Spectral Database

Roy S. Berns

Colorimetric and spectral gamuts are useful for the design of imaging systems such as display and print, to evaluate encoding errors for digital photography, for spectral reconstruction, and for lighting design. An artist paint spectral database was developed that includes spectra, colorimetry, eigenvectors, and optical data to produce additional spectra if desired. Nineteen acrylic-dispersion paints were sampled and Kubelka-Munk theory with the Saunderson correction was used to characterize each paint’s optical properties. Each chromatic paint or hue-adjacent paints were mixed computationally with white and with black at a range of concentrations producing approximately uniform sampling in CIELAB. In total, there are 23 hues and one gray scale with 770 unique spectra. IS&T Color and Imaging Conference, submitted (2016). download proceedings, download Excel spreadsheet

Modification of CIEDE2000 for Assessing Color Quality of Image Archives

Roy S. Berns

Evaluating color accuracy of image archives is accomplished using test targets, colorimetric measurements, and total color difference calculations. Both CIELAB and CIEDE2000 are used with the later often preferred being an international standard and having a weighting function for chroma position. Its lightness weighting function is problematic when used for image archiving because it allows for greater lightness errors for dark colors, colors critical in defining image quality. A statistical analysis was performed on data used to derive CIEDE2000. The results do not support the weighting function for lightness. For imaging applications, it is recommended that the lightness weighting function be replaced with unity. IS&T Archiving Conference in press(2016). download proceedings

Using Maya to Create a Virtual Museum

Brittany D. Cox and Roy S. Berns

Surface normal and diffuse color maps were rendered for different lighting configurations using computer graphics software. The maps were measured using the four-light imaging system developed for the Studio for Scientific Imaging and Archiving of Cultural Heritage. IS&T Archiving Conference 51-55 (2015). download proceedings

Imaging Artwork in a Studio Environment for Computer Graphics Rendering

Brittany D. Cox and Roy S. Berns

The four-light imaging system developed by T. Chen and Berns was improved using a heirarchical selection technique to remove specular highlights rather than cross-polarization. IS&T/SPIE Electronic Imaging 939803-939803 (2015). download proceedings

Increasing the Versatility of Digitizations through Post-Camera Flat-Fielding

Joel Witwer and Roy S. Berns

When lighting to enhance surface texture, there is significant fall off. An image of this falloff using a white board can be used for archiving or not used to improve realism. IS&T Archiving Conference 110-113 (2015). download proceedings

ETRGB: An Encoding Space for Artwork Imaging

Roy S. Berns and Maxim Derhak

A new encoding space, ETRGB (Extended Tristimulus RGB), was derived to facilitate accurate archiving of modern artist materials such as metallic flakes and interference pigments. IS&T Archiving Conference 74-77 (2015). download proceedings

 

Technical Reports

Spectral Imaging Using a Liquid Crystal Tunable Filter – Part II

Farhad Moghareh Abed and Roy S. Berns

A practical workflow was developed for the spectral calibration of a multispectral imaging system using liquid crystal tunable filter (LCTF) based . The workflow calibrated the system such the scale of spectral reflectance factor was transfered to the imaging system. The novel aspect of this research was a spatial correction accounting for the angular dependency of interference filters. (Refereed article below) download report

Artist Paint Target (APT): A Tool for Verifying Camera Performance

Roy S. Berns

A new 24-patch target was developed to verify colorimetric accuracy for artist paints. download report, auxiliary data )

Spectral and Color Characteristics of Broncolor Pulso F4 Strobe with UVE Protection Dome

Roy S. Berns

Data were compiled for a Broncolor F4 strobe with UVE protection dome and CIE daylight spectral power distributions with equivalent correlated color temperature, distribution temperature, and 5500K. download report, auxiliary data

Camera Encoding Evaluation for Image Archiving of Cultural Heritage

Roy S. Berns

A large set of colors were compiled including eight fluorescent artist paints, a sampling of glossy high-chroma artist paints, computationally extended artist paints, the Pointer gamut, and a computationally extended Pointer gamut. Their colorimetric data were used to evaluate potential encoding errors for sRGB, AdobeRGB(1998), ProPhotoRGB, and ProStarRGB. download report

A New Encoding System for Image Archiving of Cultural Heritage: ETRGB

Roy S. Berns and Maxim Derhak

A new encoding space, ETRGB (Extended Tristimulus RGB), was developed to insure modern artist material such as those containing metals and interference pigments are encoded without errors caused by clipping or gamut mapping. (Proceeding below) download report, auxiliary data - ICC profile)

Evaluating Solid State and Tungsten-Halogen Lighting for Imaging Artwork via Computer Simulation

Roy S. Berns

Solid state lighting was evaluated for use as a taking illuminant in the imaging of artwork. Based on computer simulation of camera signals, a high color-rendering solid state light achieved the same accuracy as a Xenon strobe. download report

Spectral Sensitivity and Transmittance Measurements of a Sinar 86H CTM Dual-RGB Digital Camera

Roy S. Berns and Yixuan Wang

The spectral sensitivity and spectral transmittance factor of the sensor and filters of a Sinar CTM (color to match) digital camera system were measured using a calibrated monochromatic source and spectrophotometer, respectively. download report, auxiliary data

Geometric Distortions in a Canon EF 50mm f/2.5 Macro Lens

Joel Witwer

The geometric distortion was evaluated for a Canon lens. download report

Lighting Evaluation for Aesthetic Imaging

Joel Witwer

The lighting capabilities of the Studio for Scientific Imaging and Archiving of Cultural Heritage were compared with typical practices at the Metropolitan Museum of Art. download report

Other

Inpainting Spreadsheet of Gamblin Conservation Colors

Roy S. Berns

Two-constant Kubelka-Munk theory with the Saunderson correction for refractive index discontinuity at the paint surface can be used to select pigments for inpainting leading to minimal metamerism. This Excel spreadsheet implements both colorimetric and spectral matching using the Gamblin Conservation Colors (circa 2000) as the optical database. The spreadsheet also includes a sheet to produce new optical data for your own paints. This is based on research by Berns and Mohammadi published in Studies in Conservation. download spreadsheet, download Studies article

 

 

 

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