Williams D, Sekiguchi N, Brainard D
Center for Visual Science, University of Rochester, NY 14627-0270.
Proc Natl Acad Sci U S A. 1993 Nov 1;90(21):9770-7. doi: 10.1073/pnas.90.21.9770.
This paper evaluates the role of various stages in the human visual system in the detection of spatial patterns. Contrast sensitivity measurements were made for interference fringe stimuli in three directions in color space with a psychophysical technique that avoided blurring by the eye's optics including chromatic aberration. These measurements were compared with the performance of an ideal observer that incorporated optical factors, such as photon catch in the cone mosaic, that influence the detection of interference fringes. The comparison of human and ideal observer performance showed that neural factors influence the shape as well as the height of the foveal contrast sensitivity function for all color directions, including those that involve luminance modulation. Furthermore, when optical factors are taken into account, the neural visual system has the same contrast sensitivity for isoluminant stimuli seen by the middle-wavelength-sensitive (M) and long-wavelength-sensitive (L) cones and isoluminant stimuli seen by the short-wavelength-sensitive (S) cones. Though the cone submosaics that feed these chromatic mechanisms have very different spatial properties, the later neural stages apparently have similar spatial properties. Finally, we review the evidence that cone sampling can produce aliasing distortion for gratings with spatial frequencies exceeding the resolution limit. Aliasing can be observed with gratings modulated in any of the three directions in color space we used. We discuss mechanisms that prevent aliasing in most ordinary viewing conditions.
本文评估了人类视觉系统各个阶段在空间模式检测中的作用。采用一种心理物理学技术，对颜色空间中三个方向的干涉条纹刺激进行对比敏感度测量，该技术避免了包括色差在内的眼睛光学系统造成的模糊。将这些测量结果与一个理想观察者的表现进行比较，该理想观察者纳入了影响干涉条纹检测的光学因素，如视锥镶嵌中的光子捕获。人类与理想观察者表现的比较表明，神经因素影响所有颜色方向（包括那些涉及亮度调制的方向）中央凹对比敏感度函数的形状和高度。此外，当考虑光学因素时，神经视觉系统对中波敏感（M）和长波敏感（L）视锥细胞看到的等亮度刺激以及短波敏感（S）视锥细胞看到的等亮度刺激具有相同的对比敏感度。尽管为这些颜色机制提供输入的视锥亚镶嵌具有非常不同的空间特性，但后期的神经阶段显然具有相似的空间特性。最后，我们回顾了视锥采样对于空间频率超过分辨率极限的光栅会产生混叠失真的证据。在我们使用的颜色空间中三个方向的任何一个方向上调制的光栅都能观察到混叠现象。我们讨论了在大多数普通观看条件下防止混叠的机制。
