Todd James T, Norman J Farley, Mingolla Ennio
Ohio State University, USA.
Psychol Sci. 2004 Jan;15(1):33-9. doi: 10.1111/j.0963-7214.2004.01501006.x.
Visible surfaces in a natural environment often have multiple components of reflectance, including a diffuse component, by which light is scattered isotropically in all possible directions, and a specular component, by which light is reflected anisotropically within a limited range of directions. The research described in the present article was designed to investigate how these different components of reflectance influence the perception of lightness. Human observers were presented with shaded images of smoothly curved surfaces and asked to compare the relative lightness of different surface regions whose diffuse and specular components of luminance were independently manipulated. The results revealed that observers are able to discount the presence of specular highlights so that the relative lightness among different regions is determined almost entirely by the diffuse component of surface reflectance.
自然环境中的可见表面通常具有多种反射成分，包括漫反射成分，即光线在所有可能方向上各向同性地散射；以及镜面反射成分，即光线在有限的方向范围内各向异性地反射。本文所述的研究旨在探究这些不同的反射成分如何影响明度感知。向人类观察者展示平滑曲面的阴影图像，并要求他们比较不同表面区域的相对明度，这些区域的漫反射和镜面反射亮度成分是独立控制的。结果表明，观察者能够忽略镜面高光的存在，从而不同区域之间的相对明度几乎完全由表面反射率的漫反射成分决定。
