Webster M A, Miyahara E
Department of Psychology, University of Nevada, Reno 89557, USA.
J Opt Soc Am A Opt Image Sci Vis. 1997 Sep;14(9):2355-66. doi: 10.1364/josaa.14.002355.
Natural images have a characteristic spatial structure, with amplitude spectra that decrease with frequency roughly as 1/f. We have examined how contrast (pattern-selective) adaptation to this structure influences the spatial sensitivity of the visual system. Contrast thresholds and suprathreshold contrast and frequency matches were measured after adaptation to random samples from an ensemble of images of outdoor scenes or of synthetic images formed by filtering the amplitude spectra of noise over a range of spectral slopes. Adaptation selectively reduced sensitivity at low-to-medium frequencies, biasing contrast sensitivity toward higher frequencies. The pattern of aftereffects was similar for different natural image ensembles but varied with large changes in the slope of the noise spectra. Our results suggest that adaptation to the spatial structure in natural scenes may exert strong and selective influences on perception that are important in characterizing the normal operating states of the visual system.
自然图像具有独特的空间结构，其振幅谱随频率大致以1/f的规律下降。我们研究了对这种结构的对比度（模式选择性）适应如何影响视觉系统的空间敏感性。在适应了从室外场景图像集合或通过在一系列频谱斜率上对噪声的振幅谱进行滤波形成的合成图像中随机抽取的样本后，测量了对比度阈值、超阈值对比度和频率匹配。适应选择性地降低了低至中频的敏感性，使对比度敏感性偏向高频。不同自然图像集合的后效模式相似，但随噪声谱斜率的大幅变化而变化。我们的结果表明，对自然场景中空间结构的适应可能对感知产生强烈且选择性的影响，这对于表征视觉系统的正常运行状态很重要。
