Title: Colours of retroreflective sign materials when illuminated by high-intensity-discharge headlamps

Authors: M. Sivak, C.J. Simmons, M. Flannagan

Addresses: University of Michigan Transportation Research Institute, Ann Arbor, Michigan 48109-2150, USA. ' University of Michigan Transportation Research Institute, Ann Arbor, Michigan 48109-2150, USA. ' University of Michigan Transportation Research Institute, Ann Arbor, Michigan 48109-2150, USA

Abstract: This analytical study evaluated the colorimetric properties of retroreflective traffic signs when illuminated by high-intensity-discharge (HID) headlamps. Two aspects were investigated: (1) calorimetric shifts of individual sign materials when illuminated by HID light sources as opposed to halogen: and (2) calorimetric separations of the red sign material from the yellow, orange, and brown sign materials when illuminated by HID light sources. Spectral reflectances of sign materials and spectral power distributions of HID (and halogen) headlamps were used to deprive the CIE tristimulus values for the sign materials. These values were then transformed into the CIELAB space - a perceptually uniform colour space. The results of the analyses indicate that the magnitude of the colorimetric shift increased with increasing correlated colour temperature of the HID light source. The resulting colorimetric separations of red from yellow, orange, and brown far the HID light sources also tended to increase with increasing correlated colour temperature, with the higher-temperature HID light source tested yielding greater colorimetric separations than halogen.

Keywords: colour perception; headlighting; colorimetric properties; retroreflective traffic signs; sign illumination; high intensity discharge; HID headlamps; HID headlights; vehicle headlamps; vehicle headlights.

DOI: 10.1504/IJVD.1991.061686

International Journal of Vehicle Design, 1991 Vol.12 No.3, pp.284 - 295

Published online: 27 May 2014 *

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