Uttal W R, Baruch T, Allen L
Department of Industrial and Management Systems Engineering, Arizona State University, Temple 85287-5906, USA.
Percept Psychophys. 1995 Jul;57(5):668-81. doi: 10.3758/bf03213272.
This paper explores the ways in which combinations of image degradations affect discrimination. Nine experiments are described that examine the discriminability of visual images that are degraded with three types of information reducing transformations: random punctate visual interference, low-pass spatial frequency filtering, and local area (i.e., block) averaging. The results of these experiments characterize a powerful visual ability to discriminate highly degraded stimuli unless that ability is severely challenged by relatively high levels of random visual interference. Discriminative commutativity of the orders in which the other two degradations are imposed is demonstrated. That is, the order in which the degradations are applied does not affect the final discriminative outcome. This result is in contrast to predictions from relevant mathematics and direct examination of the images produced by both orders of degradation. The commutativity is attributed to the particularly strong effect of the low-pass spatial frequency filtering degradation on the discrimination process. This study also demonstrates that combinations of degradations in a discrimination task always result in a reduction in performance, and never in the improvement that has been reported for recognition. This difference is attributed to the fact that form discrimination is mediated mainly by local features and high-frequency spatial components, whereas recognition is mediated mainly by global features and low-frequency spatial components.
本文探讨了图像退化组合影响辨别力的方式。文中描述了九个实验，这些实验检验了通过三种信息缩减变换而退化的视觉图像的可辨别性，这三种变换分别是：随机点状视觉干扰、低通空间频率滤波和局部区域（即块）平均。这些实验的结果表明，存在一种强大的视觉能力，能够辨别高度退化的刺激，除非这种能力受到相对高水平随机视觉干扰的严重挑战。实验证明了施加另外两种退化的顺序具有辨别可交换性。也就是说，应用退化的顺序不会影响最终的辨别结果。这一结果与相关数学预测以及对两种退化顺序所产生图像的直接检查结果形成对比。这种可交换性归因于低通空间频率滤波退化对辨别过程的特别强烈影响。本研究还表明，辨别任务中退化的组合总是导致性能下降，而从未出现过如识别任务中所报道的性能提高情况。这种差异归因于这样一个事实，即形状辨别主要由局部特征和高频空间成分介导，而识别主要由全局特征和低频空间成分介导。
