Publications by authors named "Osamu Masuda"

In a previous study based on monitor simulations of artistic paintings, it was found that the average correlated color temperature (CCT) of daylight preferred by a large set of observers to illuminate paintings was around 5100 K. The goal of the present study was to test if this result holds in real viewing conditions, i.e.

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Light sources with three spectral bands in specific spectral positions are known to have high-color-discrimination capability. W. A.

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Spectral optimization for naturalness and preference was carried out empirically in a set of psychophysical experiments in which observers adjusted the spectral composition of the illumination to render commercial food counters containing a variety of fruits and vegetables as well as meat and fish. The scenes were simulated with high chromatic precision on a calibrated computer monitor from data obtained by hyperspectral imaging. The illuminants were daylight-like and their metamers, representing a set of nearly arbitrary spectra.

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The optimal spectral profiles of lighting for naturalness, individual preference, and chromatic diversity were estimated with psychophysical experiments in which observers selected illuminants from a set of metamers of D65 to render outdoor and indoor scenes. For naturalness, the illuminant selected was more spectrally structured than daylight and had a low color rendering index. For preference, the illuminant was similar but produced colors a little more saturated.

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The spectrum of modern illumination can be computationally tailored considering the visual effects of lighting. We investigated the spectral profiles of the white illumination maximizing the theoretical limits of the perceivable object colors. A large number of metamers with various degrees of smoothness were generated on and around the Planckian locus, and the volume in the CIELAB space of the optimal colors for each metamer was calculated.

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We measured the temporal summation properties of paired flashes to investigate the temporal responses of the chromatic channel in peripheral vision in comparison with those of the luminance channel. The size of the stimulus was scaled according to the cortical magnification factor. The temporal response was biphasic to complementary-chromatic pulse pairs, and was accelerated in peripheral vision in the same way as luminance pulse pairs.

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