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Trichromatic reflectance capture using a tunable light source: Setup, characterization and reflectance estimation

: Tanksale, Tejas Madan; Urban, Philipp


Imai, Francisco H.; Segovia, Maria V. Ortiz; Urban, Philipp ; Society for Imaging Science and Technology -IS&T-:
IS&T International Symposium on Electronic Imaging 2016. Measuring, Modeling, and Reproducing Material Appearance. Online resource : February 14-18, 2016, San Francisco
Springfield/Va.: IS&T, 2016
Art. 355, 7 S.
International Symposium on Electronic Imaging <2016, San Francisco/Calif.>
Fraunhofer IGD ()
Lead Topic: Digitized Work; Research Line: Computer graphics (CG); Research Line: Computer vision (CV); reflectance; colorimetry

A research project is underway to develop a gonio imager particularly dedicated to sample the Bidirectional Reflectance Distribution Function (BRDF) of materials and material compositions employed and created by multimaterial 3D printers. It comprises an almost colorimetric RGB camera and a spectrally tunable light source. In this paper, we investigate an important part of this system, particularly the approach to estimate reflectances from RGB values acquired under multiple illuminants. We first characterize the system by estimating the spectral sensitivities of the camera. Then, we use the sensitivities, a set of illuminants produced by the tunable light source and the corresponding sensor responses to estimate reflectances. For evaluating this approach, we measure the Neugebauer primary reflectances of a polyjet printer employing highly translucent photo-polymer printing materials colored in cyan, magenta, yellow and white. Spectral and colorimetric deviations to spectroradiometric comparison measurements (average 0.67 CIEDE2000 units / 0.0286 spectral RMS) are within the inter-instrument variability of hand-held spectrophotometers used in graphic arts for prints on paper.