Psychophysics with junctions in real images.
Psychophysics with junctions in real images.
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DOI：
10.1167/2.7.131
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发表时间：
2010-03
期刊：
影响因子：
1.7
通讯作者：
Josh H. McDermott
中科院分区：
文献类型：
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作者：
Josh H. McDermott
在图像轮廓的交叉处形成的连接被认为在视觉中起着重要和早期的作用。对交叉点的兴趣可以部分归因于这样的概念，即它们是容易检测的局部图像特征，但仍然提供关于世界上重要事件的有价值的信息，例如遮挡和透明度。在这里，我测试的概念，有本地定义的路口在真实的图像，可能会发现简单的，早期的视觉机制。人类观察者被用作测量真实的图像的局部区域中可用的视觉信息的工具。一组观察者被要求标记一组真实的图像中一个边缘遮挡另一个边缘的所有点。第二组观察者呈现这些图像的可变大小的圆形子区域，并被要求判断这些区域是否以遮挡点为中心。如果连接点可见，这项任务很容易，但我发现对于小区域，性能很差，直到观察者获得相当大的（直径约50像素）区域才接近天花板水平。对照实验排除了这种效应仅仅是由于多个尺度上的连接的可能性。本文报道的实验表明，尽管真实的图像中的一些连接是局部定义的并且可以用简单的机制检测到，但很大一部分需要使用更复杂和全局的过程。这就提出了在这种情况下可能无法在现场解释之前检测到交叉点的可能性。
Junctions, formed at the intersection of image contours, are thought to play an important and early role in vision. The interest in junctions can be attributed in part to the notion that they are local image features that are easy to detect but that nonetheless provide valuable information about important events in the world, such as occlusion and transparency. Here I test the notion that there are locally defined junctions in real images that might be detected with simple, early visual mechanisms. Human observers were used as a tool to measure the visual information available in local regions of real images. One set of observers was made to label all the points in a set of real images where one edge occluded another. A second set of observers was presented with variable-size circular subregions of these images, and was asked to judge whether the regions were centered on an occlusion point. This task is easy if junctions are visible, but I found performance to be poor for small regions, not approaching ceiling levels until observers were given fairly large (approximately 50 pixels in diameter) regions over which to make the judgment. Control experiments ruled out the possibility that the effects are just due to junctions at multiple scales. Experiments reported here suggest that, although some junctions in real images are locally defined and can be detected with simple mechanisms, a substantial fraction necessitate the use of more complex and global processes. This raises the possibility that junctions in such cases may not be detected prior to scene interpretation.