This paper is part of a project to establish the optimal spectral power distributions of LED light sources for use in offices, commerce and homes. The present paper introduces the most important aspects of home lighting and provides recommendations for optimum spectra in the home environment. Visual experiments were carried out in a real scale kitchen/dining room and in a living room environment with the participation of nearly 100 observers. Results have been evaluated with the help of the analytic hierarchy process (AHP) and a modified Thurstone method. As a result of the investigation, optimal spectral power distributions for the home environment are described.

CIE colorimetry breaks down when lights produced by narrow band RGB-LEDs are matched with broadband lights. A colour matching experiment was set up and matches in a number of parts of the chromaticity diagram have been made, to determine the magnitude of the discrepancy. Differences between visual and instrumental matches increase as one moves in the chromaticity diagram from yellowish white lights toward greenish and bluish lights.CIE TC 1-36 recently suggested newly defined cone fundamentals: Applying a transformation of these to a space similar to the CIE XYZ space enables a much better prediction of the matches to be made. The difference between the visual match and its instrumental prediction decreases by a factor of two or even more.The use of a cone fundamental based colorimetric system is recommended for LED colorimetry.

Colour rendering for picture gallery lighting means colour fidelity, showing the colours of the pictures as seen by the painter in the light he used in creating the pictures. As up to the beginning of the 20th century illuminance high enough for good colour vision was possible only in daylight, daylight would be the optimum illuminant. For art preservation and energy saving reasons this is not feasible. Museums often use light of 3500 K correlated colour temperature (CCT). A method is described that takes chromatic adaptation into consideration to determine the spectral power distribution producing least colour distortion of object colours while changing from a higher adaptation luminance at 6500 K to 3500 K illumination at a lower adaptation luminance. The method can be used for any CCT and adaptation luminance values.

This paper provides recommendations for optimum LED light spectra in shop environments. The main aspects of the research were to elaborate the optimal LED spectral power distribution for the lighting of different colour textiles, fruits and vegetables, meat and bakery products. The spectrum was tailored towards different colour quality metrics such as the colour rendering index and the colour quality scale. Small scale investigations with eye-tracker studies were carried out by Osram Opto Semiconductors at the University of Regensburg and full scale experiments were conducted at the University of Pannonia during the project in order to determine which metric correlates best to the preference of the observers. Results of the psychophysical have been evaluated with the help of analytic hierarchy process and a modified Thurstone method. As a result of the investigation, optimal spectral power distributions for shop environment are described.

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The European Union has financed a 3-year research project to establish optimal spectral power distributions of LED light sources for use in offices, commerce and homes. This paper summarizes the general questions relevant to colour preference investigations and introduces the investigations performed in the three laboratories that participated in the research. Subsequent papers will deal with details of the investigations and provide recommendations for optimum spectra in different indoor applications.

ObjectiveThe aim of this in vitro study is to evaluate the masking ability of polymer‐infiltrated ceramic‐network materials (PICN) with different translucencies and thicknesses on multiple types of substrates.Materials and MethodsCeramic samples were prepared of VITA ENAMIC blocks in two different translucencies (2M2‐T, 2M2‐HT) in a thickness range of 0.5–2.5 mm (±0.05 mm). Layered specimens were obtained using composite substrates in nine shades and transparent try‐in paste. Spectral reflectance of specimens was measured using a Konica Minolta CM‐3720d spectrophotometer and D65 standard illumination. CIEDE2000 color difference (ΔE00) between two samples was evaluated using 50%:50% perceptibility and acceptability thresholds. Specular component of the reflection was examined with Specular Component Excluded (SCE) and Included (SCI) settings. Statistical evaluation was performed by linear regression analysis, Kruskal–Wallis test, and multiplicative effect analysis.ResultsAn increase in thickness of 0.5 mm reduces ΔE00 of HT samples to 73.5%, of T samples to 60.5% (p < 0.0001). Five substrates with HT specimens, and three substrates with T specimens had significantly different results from average (p < 0.05). There is a significant difference between SCE and SCI data depending on the wavelength (p < 0.0001).ConclusionsMasking ability of PICN materials is influenced by the thickness and translucency of the ceramic, and by the substrate. Reflection of the examined PICN material is characterized by both diffuse and specular reflection.Clinical SignificanceAlthough PICN materials have been available on the market for 10 years now, there is a lack of information regarding their masking ability. Acquiring in‐depth data and thereby practical experience of the factors affecting the esthetics of PICN materials is essential for creating perfectly lifelike restorations.

An earlier paper has described a new method to optimise the spectral power distribution of solid state lighting systems used in museums. This paper will discuss the question of the selection of the test samples used for the spectral power distribution optimisation for the illumination of renaissance paintings. For fine tuning the spectrum the help of museum curators was needed, who remember the appearance of the pictures under traditional light sources and who were able to advise lighting engineers to tune the spectrum to obtain a pleasing appearance. The paper will show the results obtained by testing the optimum spectrum in the museum. Part 1 of the present publication dealt with a new method to optimise the spectral power distribution of Solid State Lighting systems used in museums. Part 2 will discuss the question of test samples for the illumination of renaissance paintings and will show results obtained by testing the optimum spectrum in the museum.