Morgan M J, Watt R J
Vision Res. 1984;24(12):1911-9. doi: 10.1016/0042-6989(84)90025-7.
Discrete spatial sampling of sinusoidal gratings has a detrimental effect upon vernier acuity for such stimuli if the sampling rate is less than 20 c/deg. We have examined the possibility that interpolation failure is due to masking by spatial frequency components near to the signal frequency. In an explicit masking paradigm, vernier acuity for a sine wave grating was found to be adversely affected by the presence of a masking grating falling within a critical band of frequencies near the test target. In the sampled stimulus, removal of sampling replicas similar in frequency to the test improved acuity, but the extent of the residual interference by high frequency components could not be predicted from the masking data. The high frequency interference effect depended on fixed phase relations between frequency components, creating narrow bright bars in the spatial luminance profile, and was greatly reduced by phase randomizing the sampling replicas. Various explanations of this nonlinear behaviour are discussed, including the Marr-Hildreth theory of edge detection.
如果采样率低于20周/度，对正弦光栅进行离散空间采样会对这类刺激的游标视力产生不利影响。我们研究了插值失败是否是由于信号频率附近的空间频率成分造成的掩蔽。在一个明确的掩蔽范式中，发现正弦波光栅的游标视力会受到落在测试目标附近关键频率带内的掩蔽光栅的不利影响。在采样刺激中，去除与测试频率相似的采样复制品可提高视力，但高频成分的残余干扰程度无法从掩蔽数据中预测。高频干扰效应取决于频率成分之间的固定相位关系，在空间亮度分布中产生狭窄的亮条，通过对采样复制品进行相位随机化可大大降低这种效应。讨论了这种非线性行为的各种解释，包括马尔-希尔德雷思边缘检测理论。
