Miyahara E, Smith V C, Pokorny J
Visual Sciences Center, University of Chicago, Illinois 60637.
J Opt Soc Am A. 1993 Apr;10(4):545-53. doi: 10.1364/josaa.10.000545.
Chromatic discrimination thresholds were measured with and without surrounds along two cardinal axes of chromaticity space. On one axis the level of short-wavelength-sensitive (SWS)-cone excitation was varied for constant long-wavelength-sensitive (LWS)-cone and medium-wavelength-sensitive (MWS)-cone excitations, and on the other axis there were equal and opposite changes in LWS-cone and MWS-cone excitations for constant levels of SWS-cone excitation. Results for two of three observers showed that with a dark surround, discrimination mediated by SWS cones was regulated by the level of SWS-cone excitation of the starting chromaticity, showing a function with the form of a threshold-versus-radiance function. For an equiluminant white or yellow surround, the discrimination for all three observers showed a minimum at the level of SWS-cone excitation of the surround, giving a V-shaped function for the white surround. An additional experiment with dimmer white surrounds indicated that while the minimum remained at the white point, the function gradually changed toward the shape with a dark surround. Discrimination thresholds mediated by LWS and MWS cones with a dark surround showed a minimum near the LWS-cone excitation of equal-energy white, giving a V-shaped function. The effect of yellow and white surrounds was to deepen the V. The data can be described by a model of chromatic discrimination incorporating a threshold term, a cone gain control, and an opponent gain control into two equations, one for SWS-cone discrimination and one for LWS-cone and MWS-cone discrimination.
在色度空间的两个主轴上，分别测量了有无背景光时的颜色辨别阈值。在一个轴上，对于恒定的长波敏感（LWS）锥和中波敏感（MWS）锥激发，短波敏感（SWS）锥的激发水平发生变化；在另一个轴上，对于恒定的SWS锥激发水平，LWS锥和MWS锥的激发有等量且相反的变化。三名观察者中有两名的结果表明，在黑暗背景下，由SWS锥介导的辨别受起始色度的SWS锥激发水平调节，呈现出阈值与辐射函数形式的函数关系。对于等亮度的白色或黄色背景，所有三名观察者的辨别在背景的SWS锥激发水平处显示出最小值，白色背景呈现出V形函数。一项关于较暗白色背景的额外实验表明，虽然最小值仍在白点处，但函数逐渐向黑暗背景的形状变化。在黑暗背景下，由LWS和MWS锥介导的辨别阈值在等能白色的LWS锥激发附近显示出最小值，呈现出V形函数。黄色和白色背景的效果是加深V形。这些数据可以通过一个颜色辨别模型来描述，该模型在两个方程中纳入了一个阈值项、一个锥增益控制和一个对立增益控制，一个用于SWS锥辨别，另一个用于LWS锥和MWS锥辨别。
