Impact of Illumination Correlated Color Temperature, Background Lightness, and Painting Color Content on Color Appearance and Appreciation of Paintings

© 2019, © 2019 Illuminating Engineering Society. Lighting design for art exhibitions has a significant impact on the enjoyment and understanding of the displayed artworks. In particular, the selection of the light sources and the design of the museum space affect the visitors' visual perceptions of the artworks and their color appearance. This project investigated some of the potential factors—the correlated color temperature (CCT) of the illumination, the overall color content of the painting and the lightness of its background—affecting a painting's color appearance and appreciation in a museum setting. The study involved a survey conducted in the laboratory with both naïve observers and lighting experts. The CCT of the lighting was found to be the main factor affecting the painting's appearance and the observers' overall preference for the lighting arrangements, whereas the overall hue content of the painting and the background lightness had a minor influence. Furthermore, it has been found that the perceived brightness increases along with the CCT. ispartof: LEUKOS vol:16 issue:1 pages:25-44 status: publishe

Road marking BRDF model applicable for a wide range of incident illumination conditions

To drive safely and comfortably, an adequate contrast between the road surface and road markings is needed. This contrast can be improved by using optimized road illumination designs and luminaires with dedicated luminous intensity distributions, taking advantage of the (retro)reflective characteristics of the road surface and road markings. Since little is known about road markings’ (retro)reflective characteristics for the incident and viewing angles relevant for street luminaires, bidirectional reflectance distribution function (BRDF)-values of some retroreflective materials are measured for a wide range of illumination and viewing angles using a luminance camera in a commercial near-field goniophotometer setup. The experimental data are fitted to a new and optimized “RetroPhong” model, which shows good agreement with the data [root mean squared error (RMSE) &lt; 0.13, normalized root mean squared error (NRMSE) &lt; 0.04, and the normalized cross correlation ratio (NCC) &gt; 0.8]. The RetroPhong model is benchmarked with other relevant (retro)reflective BRDF models, and the results suggest that the RetroPhong model is most suitable for the current set of samples and measurement conditions.</p

Colour Appearance Modelling for Self-luminous Colours

An experimental setup and procedure for the evaluation of self- luminous colours viewed against both dark and luminous backgrounds is presented. Physical and visual data of self-luminous colours is gathered in order to develop a Colour Appearance Model for self-luminous colours under different viewing conditions. This model is needed for the evaluation of light sources. This record was migrated from the OpenDepot repository service in June, 2017 before shutting down

CAM18sl brightness prediction for unrelated saturated stimuli including age effects

Modelling the influence of age on the perception of brightness of visual stimuli is an important topic for indoor and outdoor lighting. As people get older, the transmittance of the ocular media becomes lower, especially in the blue wavelength region. This paper reports on an experimental study aiming to evaluate how the brightness perception of red and blue stimuli is affected by the age of the observer. A matching experiment has been set up in which both young (25 years old on average) and older (70 years old on average) adult observers had to match the brightness of a blue stimulus with the brightness of a red stimulus, both surrounded by a dark background (unrelated stimuli). A significant difference in brightness perception between the two groups of observers was found. In particular, older people report a decrease in brightness perception for the blue stimuli compared to younger people. The results show that the brightness correlate of the colour appearance model CAM18sl (applied with zero luminance background) adequately predicts the matching results of young observers, but failed to predict the results obtained by the older observers. As CAM18sl is built on cone fundamentals which include the transmittance of the ocular media and consider the age of the observer as an input parameter, the authors developed the idea to substitute the cone fundamentals for a young observer by the cone fundamentals for a 70 years old observer. This updated CAM18sl performed very well for the older observer as well, on condition that the transmittance of the ocular media is isolated and kept out of the normalization of the cone fundamentals.Fil: Preciado Olvera, Oscar Ulises. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Investigación en Luz, Ambiente y Visión. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Instituto de Investigación en Luz, Ambiente y Visión; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Departamento de Luminotecnia, Luz y Visión; ArgentinaFil: Martín, Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Investigación en Luz, Ambiente y Visión. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Instituto de Investigación en Luz, Ambiente y Visión; Argentina. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Departamento de Luminotecnia, Luz y Visión; ArgentinaFil: Manzano, Eduardo Roberto. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Departamento de Luminotecnia, Luz y Visión; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán. Instituto de Investigación en Luz, Ambiente y Visión. Universidad Nacional de Tucumán. Facultad de Ciencias Exactas y Tecnología. Instituto de Investigación en Luz, Ambiente y Visión; ArgentinaFil: Smet, Kevin A. G.. Katholikie Universiteit Leuven; BélgicaFil: Hanselaer, Peter. Katholikie Universiteit Leuven; Bélgic

Stray light performance of a combined monochromator-spectrograph UV irradiance measuring instrument

Critical UV applications such as disinfections and dermatological treatments call for accurate UV spectral irradiation measurements. Single monochromators and spectrographs are not able to provide satisfying accuracy due to poor stray light rejection. The main drawbacks of a double monochromator scanning system are the need for motion synchronization, the inconvenience in performing field measurements and the time-consuming scanning approach. In this paper, a combination of a monochromator with a large bandpass and a spectrograph is proposed, which allows for accurate UV spectral irradiance measurements with short measurement times of less than 1 s, and yet with acceptable stray light rejection. Stray light levels are determined for both monochromatic and heterochromatic primary radiation using slit functions and cut-off filters. These experiments revealed a considerable UV stray light response reduction for the monochromator-spectrograph combination compared to single spectrograph instruments. The stray light performance in the 250-400 nm range matches with results obtained with double monochromator instruments. With this setup, the quality of a double dispersing instrument is combined with the quick data acquisition of a spectrograph.status: publishe

Progress in the Soft Metrology of Appearance: the Contribution of Digital Image Representations

Soft metrology has been defined by the International Commission on Illumination (CIE) as the measurement of parameters that, either singly or in combination, correlate with attributes of human response. In this paper it is described how the use of realistic image representations in psychophysical experiments has led to a better understanding of the human perception of appearance attributes, and to a change in the way of thinking about how to characterize them. In particular, advancements in the field of gloss measurement and gloss perception are considered.status: publishe

Technische Fiche Verlichting: Colorimetrie

nrpages: 31status: publishe

Spectral UV Irradiance Measurements with a Double Monochromator System and with a Combined Monochromator-Spectrograph Measuring Instrument

Critical UV applications such as disinfection and dermatological treatments call for the need for accurate UV spectral irradiation measurements. Due to poor stray light rejection, single monochromators and spectrographs are not able to provide a satisfying accuracy. For critical measurements, a scanning double monochromator offers a much better solution. At the Light&Lighting Laboratory, a combination of a single monochromator with a large bandpass and a spectrograph has been developed and it has been shown that this apparatus has stray light rejection characteristics even better than those obtained with a commercially available high-accuracy scanning UV-VIS double monochromator system. In this paper, the UV irradiance of several light sources is determined using both instruments. The experimental spectra and the stray light contributions are discussed.status: publishe