McCourt M E, Blakeslee B
Department of Psychology, North Dakota State University, Fargo 58105-5075.
J Opt Soc Am A Opt Image Sci Vis. 1994 Jan;11(1):14-24. doi: 10.1364/josaa.11.000014.
The effect that induced gratings [Vision Res. 22, 119 (1982)] exert on the perceived contrast of standard gratings situated within a 0.5 degrees test field was assessed for two observers by a contrast-matching procedure. Five levels of inducing-grating contrast, CI, ranged from 0.0 to 0.75. Functions relating matching contrast, CM, to standard-grating contrast, CS, were obtained at four levels of inducing-grating contrast across a range of standard contrasts, -0.90 < or = CS < or = +0.90, where the sign denotes the spatial phase of the standard relative to the inducing grating. The matching functions possessed three distinct limbs separated by two inflection points; the limb between the inflection points represents a region of high contrast gain. Another measure, canceling contrast, was obtained at the four levels of inducing contrast by variation of CS until the test field appeared spatially homogeneous. Induction magnitude measured in terms of canceling contrast, CC, grew approximately linearly with CI, such that CC = 0.819 (CI). Induction magnitude determined from matching-contrast data obtained for homogeneous test fields (i.e., CM for CS = 0.0) grew as a decelerating function of inducing-grating contrast, such that CM = 0.308(CI]1.8 + 0.096), effectively asymptoting at a contrast of approximately 0.275 for CI > or = 0.50. When the difference between the absolute values of matching and standard contrast, magnitude of CM-magnitude of CS, is plotted against the ratio of standard to inducing-grating contrast, CS/CI, the resulting functions are generally biphasic, revealing regions of both contrast overmatching (i.e., magnitude of CM > magnitude of CS) and contrast undermatching, magnitude of CM < magnitude of CS. A four parameter model is presented that accounts for many features of the raw matching functions and that is mathematically similar to Semmelroth's account of the crispening effect in brightness matching [J. Opt. Soc. Am. 60, 1685 (1970)]. The model describes matching contrast, CM, as the weighted sum of two nonlinear contrast-response functions whose inputs are CS and CS-CI. The results are discussed relative to the crispening effect (the effect of contrast adaptation on perceived contrast) and to similarities and differences in luminance and contrast-domain visual processing.
通过对比匹配程序，针对两名观察者评估了诱导光栅[《视觉研究》22, 119 (1982)]对位于0.5度测试视野内的标准光栅的感知对比度所产生的影响。诱导光栅对比度CI有五个水平，范围从0.0到0.75。在一系列标准对比度 -0.90 ≤ CS ≤ +0.90（其中符号表示标准光栅相对于诱导光栅的空间相位）下，在四个诱导光栅对比度水平上获得了将匹配对比度CM与标准光栅对比度CS相关联的函数。匹配函数具有由两个拐点分隔的三个不同分支；拐点之间的分支代表高对比度增益区域。通过改变CS直到测试视野在空间上看起来均匀，在四个诱导对比度水平上获得了另一个测量值，即抵消对比度。以抵消对比度CC衡量的诱导幅度随CI近似线性增长，使得CC = 0.819(CI)。从均匀测试视野获得的匹配对比度数据（即CS = 0.0时的CM）确定的诱导幅度作为诱导光栅对比度的减速函数增长，使得CM = 0.308(CI)^1.8 + 0.096，对于CI ≥ 0.50，在对比度约为0.275时有效渐近。当将匹配对比度与标准对比度的绝对值之差（CM的幅度 - CS的幅度）相对于标准光栅与诱导光栅对比度之比CS/CI作图时，所得函数通常是双相的，揭示了对比度过度匹配（即CM的幅度 > CS的幅度）和对比度不足匹配（CM的幅度 < CS的幅度）区域。提出了一个四参数模型，该模型解释了原始匹配函数的许多特征，并且在数学上类似于Semmelroth对亮度匹配中锐化效应的描述[《美国光学学会杂志》60, 1685 (1970)]。该模型将匹配对比度CM描述为两个非线性对比度响应函数的加权和，其输入分别为CS和CS - CI。相对于锐化效应（对比度适应对感知对比度的影响）以及亮度和对比度域视觉处理中的异同对结果进行了讨论。
