Occlusions and their relationship with the distribution of contrasts in natural images
Occlusions and their relationship with the distribution of contrasts in natural images
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DOI：
10.1016/s0042-6989(00)00099-7
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发表时间：
2000-01-01
期刊：
影响因子：
1.8
通讯作者：
Grzywacz, NM
中科院分区：
文献类型：
--
作者：
Balboa, RM;Grzywacz, NM
最近提出的一种用于早期视觉处理的类似信息论的假设（最小局部粗糙假设）解释了水平细胞强度的自适应行为。已经证明，要使这一点成立，一个点被遮挡边界穿过的概率必须作为对比度的函数超线性增加（即，具有正二阶导数）。我们通过分析自然图像中对比度的分布及其与遮挡边界的关系来测试这种条件。我们发现自然图像中对比度的分布作为对比度的函数呈指数下降。此外，自然图像中一个点被遮挡边界穿过的概率总是随着对比度的增加而增加，直到达到 1。这种上升往往是超线性的，并且噪声的添加（在低强度下）增加了超线性，将曲线的上升部分移向更高的对比度。这些发现支持了最小局部粗糙假说，该假说提出早期视网膜处理的主要作用之一是根据先前关于自然图像的知识从视觉世界中提取最佳边缘、对比度和亮度属性。 (C) 2000 Elsevier Science Ltd. 保留所有权利。
An Information-Theory-like hypothesis recently proposed for early visual processing (the Minimal Local-Asperity hypothesis) accounts for the adaptive behavior with intensity of horizontal cells. It has been shown that for this to hold, the probability that a point is traversed by an occluding border must increase supralinearly (that is, with a positive second derivative) as a function of contrast. We test this condition by analyzing the distribution of contrasts and their relationship with occluding borders in natural images. We find that the distribution of contrasts in natural images falls exponentially as a function of contrast. Moreover, the probability that a point is traversed by an occluding border in natural images always rises with contrast until reaching one. This rise tends to be supralinear and addition of noise (at low intensities) increases the supralinearity, shifting the rising portion of the curve towards higher contrasts. These findings lend support to the Minimal Local-Asperity hypothesis, which proposes that one of the main roles of early retinal processing is to extract optimally edge, contrast, and luminance attributes from the visual world based on previous knowledge about natural images. (C) 2000 Elsevier Science Ltd. All rights reserved.