Nieves Juan Luis, Nascimento Sérgio M C, Romero Javier
Department of Optics, University of Granada, 18071 Granada, Spain.
J Opt Soc Am A Opt Image Sci Vis. 2012 Feb 1;29(2):A240-6. doi: 10.1364/JOSAA.29.00A240.
Essential to sensory processing in the human visual system is natural illumination, which can vary considerably not only across space but also along the day depending on the atmospheric conditions and the sun's position in the sky. In this work, edges derived from the three postreceptoral Luminance, Red-Green, and Blue-Yellow signals were computed from hyperspectral images of natural scenes rendered with daylights of Correlated Color Temperatures (CCTs) from 2735 to 25,889 K; for low CCT, the same analysis was performed using Planckian illuminants up to 800 K. It was found that average luminance and chromatic edge contrasts were maximal for low correlated color temperatures and almost constants above 10,000 K. The magnitude of these contrast changes was, however, only about 2% across the tested daylights. Results suggest that the postreceptoral opponent and nonopponent color vision mechanisms produce almost constant responses for color edge detection under natural illumination.
自然光照对于人类视觉系统的感官处理至关重要，它不仅会因空间不同而有很大差异，而且会根据大气条件和太阳在天空中的位置随时间发生显著变化。在这项研究中，从相关色温（CCT）为2735至25889K的日光渲染的自然场景的高光谱图像中计算出源自三种感受器后亮度、红-绿和蓝-黄信号的边缘；对于低色温情况，使用高达800K的普朗克光源进行相同分析。研究发现，对于低相关色温，平均亮度和色度边缘对比度最大，而在10000K以上几乎保持恒定。然而，在测试的日光范围内，这些对比度变化的幅度仅约为2%。结果表明，感受器后对立和非对立颜色视觉机制在自然光照下对颜色边缘检测产生几乎恒定的响应。
