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In the design of professional luminaires, improving visibility has always been a core target. Recently, it has become clearer that especially for consumer lighting, generating an appropriate atmosphere and pleasant feeling is of almost equal importance. In recent studies it has been shown that the perception of an atmosphere can be described by four variables: cosiness, liveliness, tenseness, and detachment. In this paper we compare the perception of these lighting characteristics when viewed in reality with the perception when viewing a simulated picture. Replacing reality by a picture on a computer screen such as an LCD monitor, or a piece of paper, introduces several differences. These include a reduced dynamic range, reduced maximum brightness and quantization noise in the brightness levels, but also in a different viewing angle, and a different adaption of the human visual system. Research has been done before to compare simulations with photographs, and simulations with reality. These studies have focused on 'physical variables', such as brightness and sharpness, but also on naturalness and realism. We focus on the accuracy of a simulation for the prediction of the actual goal of a lot of luminaires: atmosphere creation. We investigate the correlation between perceptual characteristics of the atmosphere of a real-world scene and a simulated image of it. The results show that for all 4 tested atmosphere words similar main effects and similar trends (over color temperature, fixtures, intensities) can be found in both the real life experiments and the simulation experiments. This implies that it is possible to use simulations on a screen or printout for the evaluation of atmosphere characteristics.

LED lighting can provide pleasant temporal dynamics, though the understanding of what constitutes pleasant has so far remained largely in the experiential domain of lighting designers. Only recently has research begun to uncover what affects preferences for dynamic lighting. Based on the insight that visible, yet subtle, dynamic lighting is desirable, an experiment was conducted which studied the influence of the speed and amplitude of periodic temporal color transitions on the thresholds for visibility and perceived subtlety. Using RGB LED lights to illuminate a wall in a living room setting, stimuli with periodic color transitions were presented to 40 observers, half of whom evaluated whether the dynamic transitions were visible, and half of whom evaluated whether the dynamics were subtle. The observers data were fit using psychometric surfaces over the independent variables speed and amplitude of transitions. The 2D contours at the middle of the height of these surfaces were taken as thresholds. Experimental confidence was estimated via parametric bootstrapping, showing significant effects of the location and direction in colorspace in which the transitions were made, further strengthening the need for a temporal difference based color space. Interestingly, a distinct difference between the threshold for visibility and the threshold for subtlety can be seen, allowing for the creation of transitions that are both visibly and yet subtly dynamic. The results indicated that observers are more sensitive to hue changes than to chroma changes, and observers are more sensitive to hue changes in the orange region than to those in the blue region. Additionally, questionnaire responses provided insight into interpretations of the wordsubtle, understood to be pleasant, gentle, and smooth, which are also terms used to describe desired characteristics of dynamic lighting.