佐藤 浩一郎

In this study, to clarify factors related to impression evaluation of decorative films, we focused on spectral radiance ratio characteristics and attempted to clarify the relationship between these characteristics and impression evaluation. As a result, two characteristics: the "wavelength-dependent type", in which the spectral radiance ratio characteristic varies significantly with the magnitude of the wavelength, and the "angle-dependent type", in which it varies significantly with the angle of measurement, are each related to impression evaluation, such as depth perception. The former feature can be expressed as the difference between the maximum and minimum values of the spectral radiance ratio at highlights and was found to be related to saturation. On the other hand, the latter feature can be expressed by the difference between the maximum values of the spectral radiance ratios for semi-shades and shades, and was shown to be related to the difference in their luminance. Thus, the impression of the decorative film can be expressed by the spectral radiance ratio.

Previous studies have reported that depth perception is a major factor in the visual impression evaluation of various materials, such as wood and metal, and that the spectral radiance ratio may be involved in the depth perception evaluation of red materials. In this study, we focused on decorative films, that have been widely used in products in recent years and investigated the influence of their transparent layers and color on the spectral radiance ratio. As a result, it was confirmed that the thickness of the transparent layer on the surface of most decorative films has almost no effect on the spectral radiance ratio. It was also found that the spectral radiance ratio can be expressed in various colors, such as red, green, and blue. Furthermore, it was shown that the difference between the maximum and minimum values of the spectral radiance ratio under the highlight, which is close to the specular reflection light from the decorative films, has a high correlation with saturation and is related to impression evaluation.