May 2019
Spotlight Summary by Kevin Houser
Perceived speed of changing color in chroma and hue directions in CIELAB
The optical radiation from LEDs of different emission spectra can be spatially integrated to create light of virtually any color, from highly saturated, to mildly tinted, to any correlated color temperature (CCT) of nominally white light. This degree of spectral control is one of the great opportunities afforded by LEDs. It is also a formidable challenge. What spectra best support different end-use applications? What degree of color variability is perceptible? In what manner does perceptibility of color differences relate to acceptability, and how does acceptability vary with application? In order to transition from these questions, to theories, to practice, models are needed that adequately represent human color perceptions.
The context of this present work is applications that employ dynamic colored light for reasons of amenity or attractiveness. The authors observed that perceptibly smooth color transitions are generally preferred, and that perceptibly smooth transitions between different chromas and hues are perceived as having different speeds. For example, a hue transition near yellow may be perceived as occurring faster than a hue transition near blue, even when both transitions have the same rate of change in color difference (ΔE*ab/s) and cover the same period of time. The authors developed an experiment to determine temporal light transitions that have perceptually equal rates of change. They conclude that CIELAB is not perceptually uniform for temporal color transitions, an expected result since CIELAB was not developed to describe temporal color differences, and they found better perceptual uniformity by expressing speeds in a modified Derrington-Krauskopf-Lennie (DKL) space. The results not only stand on their own merit, but also lay the groundwork toward the authors' goal of developing a temporally uniform color space.
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The context of this present work is applications that employ dynamic colored light for reasons of amenity or attractiveness. The authors observed that perceptibly smooth color transitions are generally preferred, and that perceptibly smooth transitions between different chromas and hues are perceived as having different speeds. For example, a hue transition near yellow may be perceived as occurring faster than a hue transition near blue, even when both transitions have the same rate of change in color difference (ΔE*ab/s) and cover the same period of time. The authors developed an experiment to determine temporal light transitions that have perceptually equal rates of change. They conclude that CIELAB is not perceptually uniform for temporal color transitions, an expected result since CIELAB was not developed to describe temporal color differences, and they found better perceptual uniformity by expressing speeds in a modified Derrington-Krauskopf-Lennie (DKL) space. The results not only stand on their own merit, but also lay the groundwork toward the authors' goal of developing a temporally uniform color space.
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Article Information
Perceived speed of changing color in chroma and hue directions in CIELAB
Xiangzhen Kong, Michael J. Murdoch, Ingrid Vogels, Dragan Sekulovski, and Ingrid Heynderickx
J. Opt. Soc. Am. A 36(6) 1022-1032 (2019) View: Abstract | HTML | PDF