We analyze the effect of perturbations on the estimation of Depth from Defocus (DFD) implemented by changing the focus setting (e.g., axially moving the sensor). The analysis yields the optimal change of focus setting, and the spatial frequencies for which estimation is most robust. For stable estimation at all spatial frequencies, the change in focus setting should be less than twice the depth...

When reading, low-level visual properties of text are acquired from central vision during brief fixational pauses, but the effectiveness of these properties may differ in older age. To investigate, a filtering technique displayed the low, medium, or high spatial frequencies of text falling within central vision as young (18-28 years) and older (65+ years) adults read. Reading times for normal t...

The existence of a second-order motion system distinct from both the first-order and feature tracking motion systems remains controversial even though many consider it well established. In the present study, the texture contribution to motion was measured within and beyond the spatial acuity of attention by presenting the stimuli in the near periphery where the spatial resolution of attention i...

It has been suggested that visual scene recognition is mainly based on spatial frequency (Fourier) analysis of the image. This analysis starts with processing low spatial frequencies (LSF), followed by processing high spatial frequencies (HSF). Within the framework of the spatial frequency analysis, the right/left hemisphere would be predominantly involved in LSF/HSF analysis, respectively. The...

Theories on visual perception agree that scenes are processed in terms of spatial frequencies. Low spatial frequencies (LSF) carry coarse information whereas high spatial frequencies (HSF) carry fine details of the scene. However, how and where spatial frequencies are processed within the brain remain unresolved questions. The present review addresses these issues and aims to identify the cereb...

It is widely believed that local and global levels of visual stimuli are better processed in the left and right cerebral hemispheres, respectively. One classic explanation for this observation is the spatial frequency hypothesis proposed by Sergent (1982), which states that the left hemisphere is more efficient at processing high spatial frequencies, whereas the right hemisphere is better with ...

We used filtered random dot kinematograms and natural images to examine how motion detection depends the relative locations of structures defined at low and high spatial frequencies. The upper displacement limit of motion (D(max)), the lower displacement limit (D(min)) and motion coherence thresholds were unaffected by the degree of spatial coincidence between high and low spatial frequency str...

The spatial autocorrelation of allelic frequencies and geographical distances were studied at a natural population of Codium fragile in Korea. Within the C. fragile population, a strong spatial structure was observed for allozyme markers, indicating a very low amount of migration among subpopulations. The species showed a significant positive spatial autocorrelation as measured by Moran's I. Ge...