Mather G
School of Biology, University of Sussex, Brighton, UK.
Perception. 1997;26(9):1147-58. doi: 10.1068/p261147.
Images of three-dimensional scenes inevitably contain regions that are spatially blurred by differing amounts, owing to depth-of-focus limitations in the imaging apparatus. Recent perceptual data indicate that this blur variation acts as an effective cue to depth: if one image region contains sharply focused texture, and another contains blurred texture, then the two regions may be perceived at different depths, even in the absence of other depth cues. Calculations based on the optical properties of the human eye have shown that variation in blur as a function of depth follows the same course as variation in binocular disparity with depth. Computational modelling has shown that the effect of blur on single-step edges is very similar to its effect on random fractal patterns, because the two stimuli have similar Fourier amplitude spectra. Blur discrimination thresholds for the two stimuli were also very similar, and could be predicted by a model based on high-spatial-frequency discrimination. A comparison of blur discrimination thresholds with the range of binocular stereopsis indicates that blur and disparity cues cover different distance ranges: stereopsis is most effective for distances relatively close to fixation, while blur information should be more effective for larger distances.
由于成像设备的景深限制，三维场景的图像不可避免地包含空间模糊程度不同的区域。最近的感知数据表明，这种模糊变化是一种有效的深度线索：如果一个图像区域包含清晰聚焦的纹理，而另一个区域包含模糊的纹理，那么即使在没有其他深度线索的情况下，这两个区域也可能被感知为处于不同的深度。基于人眼光学特性的计算表明，模糊随深度的变化与双眼视差随深度的变化遵循相同的规律。计算模型表明，模糊对单步边缘的影响与其对随机分形图案的影响非常相似，因为这两种刺激具有相似的傅里叶振幅谱。这两种刺激的模糊辨别阈值也非常相似，并且可以通过基于高空间频率辨别的模型进行预测。将模糊辨别阈值与双眼立体视觉范围进行比较表明，模糊和视差线索覆盖不同的距离范围：立体视觉对于相对靠近注视点的距离最有效，而模糊信息对于更大的距离应该更有效。
