Motoyoshi Isamu, Matoba Hiroaki
Human and Information Science Laboratory, NTT Communication Science Laboratories, NTT, Japan.
Vision Res. 2012 Jan 15;53(1):30-9. doi: 10.1016/j.visres.2011.11.010. Epub 2011 Nov 25.
In contrast to the classical findings of lightness constancy, recent psychophysical studies show the strong dependency of the perceived reflectance of a surface on the structure of the natural illumination. The present study examined this inconstancy for systematic variations in the light field and an image-based explanation for it. Observers matched the specular and diffuse reflectance of a three-dimensional object in a complex scene under a fixed light field to that in the scene under different light fields with variable mean, contrast, and gamma. For the both specular and diffuse components, the matched reflectance was relatively constant against changes in the mean illuminance but varied extensively with changes in the contrast and gamma of the light field. We found that the matching data were well predicted by the similarity of the subband histograms of the images. The results support the notion that early spatial filtering can provide a unified account of both the constancy in the perceived surface reflectance against mean illuminance and the inconstancy for higher-order illumination statistics.
与明度恒常性的经典研究结果不同，最近的心理物理学研究表明，表面的感知反射率强烈依赖于自然光照的结构。本研究针对光场的系统变化及其基于图像的解释，考察了这种非恒常性。观察者将复杂场景中固定光场下三维物体的镜面反射率和漫反射率与不同光场（具有可变均值、对比度和伽马值）场景中的进行匹配。对于镜面反射和漫反射分量，匹配的反射率相对于平均照度的变化相对恒定，但随光场对比度和伽马值的变化而大幅变化。我们发现，通过图像子带直方图的相似性可以很好地预测匹配数据。结果支持了这样一种观点，即早期空间滤波可以统一解释感知表面反射率相对于平均照度的恒常性以及高阶光照统计的非恒常性。
