A widely accepted definition of human comfort does not exist, but several metrics have been developed to quantify how much users appreciate environments, objects or interfaces. For visual comfort one of the most widely accepted approach is “that comfort is not discomfort”, because it is easier to provide quantitative and qualitative evaluation of visual discomfort parameters rather than comfort parameters that we don’t have a definition of. This paper presents the available suggestions and the results of a European research project about the visual comfort with LED lighting

The use of LEDs in museums is becoming more and more frequent. Benefits are claimed in terms of lighting quality, conservation and maintenance. Nonetheless the impact of LED light on collections preservation is not yet completely explored. The goal of this study was to evaluate, through exposure tests, the colour degradation and fading produced by LED: several white LEDs, with different colour temperature, and a traditional halogen lamp, were used to light up light-responsive samples. The results stressed the importance of the spectral distribution with respect to effective wavelengths in causing colour degradation, and in general white LEDs resulted more suitable, in terms of fading prevention, than traditional halogen light sources

The spectral reflectance of different samples of three different hues, (red, green, blue) with four different protective varnishes was measured in 8/d condition and with a goniometer equipped with a spectrometer. The samples are representative of hue and varnishes typically used in works of arts, the characterization was performed to test how the different gloss finishing induced by transparent varnishes affect the spatial distribution of the luminance coefficient in typical lighting arrangements for exposition of works of art. Nowadays the most used transparent protective varnishes are matt or glossy, natural or synthetic. The choice within them is usually made looking at mechanical, chemical (also in term of removal) and protective properties. Varnishes optical properties investigation on saturation and gloss alteration of the perceived artifacts are not usually investigated. Expected results of this research include: analysis of influences on color appearance of protective varnish according to the condition of illumination and observation, suggestion of new additional criteria for varnish selection and lighting set up exposition and reliability of 8/d measurements condition, that is a typical measurement set-up of portable instruments. Our results showed that natural varnishes are more able to change the gloss of the surfaces than synthetic ones, because the shape and intensity of the specular peak for glossy and matt natural varnish are very different. Both synthetic and natural varnishes have different behaviors at 30° or 60° light incidences: at 30° of incidence all samples have smaller variations, while at 60° of incidence the variations are larger, and for some samples the achromatic point is reache

n 2013 the European Metrology Research Program (EMRP) funded the research project, "Multidimensional Reflectometry for industry, xD-Reflect", to investigate the macroscopic optical properties related to visual appearance of modern surfaces and to develop and improve methodologies, tools and measurement devices able to provide a better description of material characteristics. One of the planned task developed several subjective tests on visual descriptors of gloss, sparkle, graininess, colour and their combined influences with reference to the measured values of reference samples. INRIM performed investigation on subjective descriptors of brightness and sparkle and their relationship with geometrical conditions of view, illuminating source characteristics, measured Radiometric Bidirectional Reflectance Distribution Function (BRDF), colorimetric attributes (CIE L*a*b*) and sparkles. This paper deals with the definition of subjective Brightness and Sparkle scales considering achromatic samples of goniochromatic materials, under LED and not LED lighting source. Key points of this study are the use of a soft metrology approach, with strong metrological characterization of the test behaviour (i.e.radiance and illuminance distribution, BRDF and sparkles of the samples), and the use of a large subject group (about 100 subject attended the test)