Justus Liebig University Giessen, Giessen, Germany.
Department of Experimental Psychology, University of Oxford, Oxford, UK.
J Vis. 2023 Jul 3;23(7):8. doi: 10.1167/jov.23.7.8.
When we look at an object, we simultaneously see how glossy or matte it is, how light or dark, and what color. Yet, at each point on the object's surface, both diffuse and specular reflections are mixed in different proportions, resulting in substantial spatial chromatic and luminance variations. To further complicate matters, this pattern changes radically when the object is viewed under different lighting conditions. The purpose of this study was to simultaneously measure our ability to judge color and gloss using an image set capturing diverse object and illuminant properties. Participants adjusted the hue, lightness, chroma, and specular reflectance of a reference object so that it appeared to be made of the same material as a test object. Critically, the two objects were presented under different lighting environments. We found that hue matches were highly accurate, except for under a chromatically atypical illuminant. Chroma and lightness constancy were generally poor, but these failures correlated well with simple image statistics. Gloss constancy was particularly poor, and these failures were only partially explained by reflection contrast. Importantly, across all measures, participants were highly consistent with one another in their deviations from constancy. Although color and gloss constancy hold well in simple conditions, the variety of lighting and shape in the real world presents significant challenges to our visual system's ability to judge intrinsic material properties.
当我们观察一个物体时，我们可以同时看到它的光泽度或哑光度、亮度和颜色。然而，在物体表面的每个点上，漫反射和镜面反射都以不同的比例混合在一起，导致了显著的空间色度和亮度变化。更复杂的是，当物体在不同的照明条件下观察时，这种模式会发生剧烈变化。本研究的目的是使用一组捕获不同物体和照明属性的图像集，同时测量我们判断颜色和光泽度的能力。参与者调整参考物体的色调、亮度、彩度和镜面反射率，使其看起来与测试物体具有相同的材料。关键的是，两个物体在不同的照明环境下呈现。我们发现，色调匹配非常准确，除了在色觉非典型的照明下。彩度和亮度恒常性通常较差，但这些失败与简单的图像统计数据很好地相关。光泽恒常性尤其差，而这些失败仅部分可以通过反射对比度来解释。重要的是，在所有测量中，参与者在偏离恒常性方面彼此之间高度一致。尽管颜色和光泽度恒常性在简单条件下表现良好，但在现实世界中，光照和形状的多样性对我们视觉系统判断内在物质属性的能力提出了重大挑战。
