CONTRAST DISCRIMINATION BY THE HUMAN VISUAL-SYSTEM
CONTRAST DISCRIMINATION BY THE HUMAN VISUAL-SYSTEM
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DOI：
10.1007/bf00326678
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发表时间：
1981-01-01
影响因子：
1.9
通讯作者：
BURTON, GJ
中科院分区：
文献类型：
--
作者：
BURTON, GJ
在日常场景的视觉中，经常在阈上背景结构的存在下观察到需要检测的特征。这些特征的检测是一项对比度辨别任务，并且通常是后续识别过程所必需的。为了提供对该任务的描述，针对具有在空间和空间频率中均被定位的亮度分布的目标确定对比度辨别测量。该调查通过测量目标的不同基础对比度、尺寸、亮度和纵横比的对比度辨别水平，扩展了该主题的早期工作。对于所有的条件下，它示出的功能变化的对比度歧视水平与基础对比度可以描述，近似地，由一个单一的曲线与1缩放常数。该常数由目标的对比度阈值水平指定。提出了一个模型来描述对比度判别过程。该模型包含2个噪声源，1个噪声源的噪声水平与目标对比度成正比，另一个噪声源的噪声水平与目标的对比度阈值水平成正比。该模型的预测结果充分描述了对比度对基本对比度的区分实验数据，并拟合了对比度差异水平的区分概率数据。一个例子给出了一个简单的应用程序的模型，以确定的可辨别的步骤的数量作为一个函数的正弦光栅目标的空间频率的对比度。
In vision of everyday scenes, features requiring detection are frequently observed in the presence of suprathreshold background structures. Detection of such features is a contrast discrimination task and is often necessary for the subsequent process of recognition. To provide a description of this task, contrast discrimination measurements were determined for targets having luminance profiles which were localized in both space and spatial frequency. The investigation extends earlier work on this topic by measurement of contrast discrimination levels for different base contrasts, sizes, luminances and aspect ratios of the targets. For all conditions, it is shown that the functional variation of the contrast discrimination level with base contrast can be described, approximately, by a single curve with 1 scaling constant. This constant is specificed by the contrast threshold level of the target. A model is proposed to described the contrast discrimination process. The model contains 2 noise sources, 1 with noise level proportional to the target contrast, and the other with noise level proportional to the contrast threshold level of the target. Predictions from the model adequately describe the experimental data of contrast discrimination against base contrast, and also fit data on the probability of discrimination against the level of contrast difference. An example is given of a simple application of the model to the determination of the number of discriminable steps in contrast as a function of the spatial frequency of a sinusoidal grating target.