A comparison of pedestal effects in first- and second-order patterns.
A comparison of pedestal effects in first- and second-order patterns.
复制标题
一阶和二阶模式中基座效应的比较。
作者：
Pi;Chien
人类视觉系统对图像中的亮度（一阶）和对比度（二阶）调制都很敏感。线性-非线性-线性模型通常用于解释二阶模式的视觉加工。在这里，我们使用了模式掩蔽范式比较一阶和二阶视觉机制，并表征其背后的非线性特性。载体是高频水平光栅（8 c/°）或二进制随机点图案;它们被添加到垂直低频（2 c/°）正弦光栅（一阶刺激）或乘以它（二阶刺激）。除了对比度（在第一阶基座中）或调制深度（在第二阶基座中）之外，用其空间特性与目标的空间特性相匹配的基座测量目标的增量辨别阈值。阈值函数显示了一个典型的一阶和二阶刺激的北斗形状。一阶刺激与不同类型的载体和二阶刺激与光栅载体的结果很好地解释了分裂抑制模型，其中易化输入除以宽带抑制输入的总和。随机点载体的二阶刺激的结果解释了一个修改的分裂抑制模型，调制深度操作。我们的研究结果表明，分裂抑制需要解释视觉歧视的一阶和二阶模式。然而，这两种类型的模式和载体的分裂抑制的来源和非线性可能是不同的。
The human visual system is sensitive to both luminance (first-order) and contrast (second-order) modulations in an image. A linear-nonlinear-linear model is commonly used to explain visual processing of second-order patterns. Here we used a pattern-masking paradigm to compare first-order and second-order visual mechanisms and to characterize the nonlinear properties underlying them. The carriers were either a high-frequency horizontal grating (8 c/°) or a binary random dot pattern; they were either added to a vertical low-frequency (2 c/°) sinusoidal grating (first-order stimuli) or multiplied by it (second-order stimuli). The incremental discrimination threshold of the target was measured with pedestals whose spatial properties matched those of the target, with the exception of contrast (in the first-order pedestal) or modulation depth (in the second-order pedestal). The threshold function showed a typical dipper shape for both first- and second-order stimuli. The results for the first-order stimuli with different types of carrier and the second-order stimuli with a grating carrier were well explained by a divisive inhibition model in which the facilitatory input was divided by the sum of broadband inhibitory inputs. The results for the second-order stimuli with a random-dot carrier were explained by a modified divisive inhibition model that operated on modulation depth. Our results suggest that divisive inhibition is required to explain visual discrimination in both first- and second-order patterns. However, the source and nonlinearity of the divisive inhibition may be different for these two types of patterns and carrier.
影响因子：
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作者：
LEGGE, GE;FOLEY, JM
通讯作者：
FOLEY, JM
纹理分离的非线性。
DOI：
10.1002/9780470514610.ch16
发表时间：
1994
期刊：
Ciba Foundation symposium
影响因子：
--
作者：
Graham,N
通讯作者：
Graham,N