Results 241 to 250 of about 1,974,870 (293)

Storage of spatial-frequency information and spatial-frequency discrimination

Journal of the Optical Society of America A, 1985
The spatial frequencies of two gratings can be discriminated when they differ by about 5%. This discrimination threshold was found to be remarkably independent of interstimulus interval in a temporal two-alternative forced-choice procedure. Discrimination threshold between parallel gratings did not change over a 50:1 range of interstimulus intervals ...
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Frequency-Shaping with Spatial Compensators

Journal of Intelligent Material Systems and Structures, 2000
Practical realizations of adaptive structures should be designed and implemented to maximize performance, robustness and efficiency. A method of frequency-shaping the compensation of an adaptive structure is developed for increased performance, system robustness and efficiency. Robustness is defined as reduced coupling to out-of-bandwidth modes, where
G. Smith, Robert Clark
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Spatial Frequency—Contingent Color Aftereffects

Science, 1976
Two-dimensional Fourier analysis of checkerboards reveals that major components are at a 45° angle to the check edges. After adapting to chromatic checkerboards, subjects who viewed achromatic grating stimuli reported that complementary color aftereffects are aligned with spatial frequency components rather than with the edges in the pattern.
J G, May, H H, Matteson
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Spatial Frequency Channels

1984
Spatial frequency channels are systems sensitive to a limited range of spatial frequencies. In the human visual system these are considered to be a population of cells with similar tuning characteristics specifically sensitive to a restricted range of the contrast sensitivity function envelope. See bandpass filter .
Alan Bundy, Lincoln Wallen
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Interferometric spatial frequency modulation imaging

Optics Letters, 2018
Interferometric spatial frequency modulation for imaging (I-SPIFI) is demonstrated for the first time, to our knowledge. Significantly, this imaging modality can be seamlessly combined with nonlinear SPIFI imaging and operates through single-element detection, making it compatible for use in scattering specimens.
Nathan, Worts, Jeff, Field, Randy, Bartels, Jason, Jones, Jeff, Broderick, Jeff, Squier   +5 more
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Spatial-frequency discrimination in cats

Journal of the Optical Society of America A, 1986
Spatial-frequency discrimination thresholds were measured in two cats by using a two-alternative forced-choice procedure. A range of standard spatial frequencies centered around the peak of the cat's contrast-sensitivity function was sampled. For comparison, discrimination thresholds were also measured in two human observers at spatial frequencies ...
R, Blake, K, Holopigian, H R, Wilson
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Spatial frequencies and emotional perception

Reviews in the Neurosciences, 2013
It has been suggested that, during evolution, specific mechanisms developed in order to optimize the detection of threats and opportunities even in perceptually degraded conditions. A naturalistic example of perceptual degradation can be found in blurry images, which contain the coarsest elements of a scene (low spatial frequencies) but lack the fine ...
DE CESAREI, ANDREA, CODISPOTI, MAURIZIO
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Perceptual latency and spatial frequency

Vision Research, 1987
Subjects estimated the perceived onset of sinusoidal gratings by adjusting a visual probe so that grating and probe were phenomenally simultaneous. The first experiment found that perceptual latency increased by an average of 21 msec over a range of 0.5-9.0 c/deg, or approximately 5 msec per octave of spatial frequency.
D M, Parker, S, Dutch
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Spatial Frequency and Selective Attention to Spatial Location

Perception, 1987
The effect of spatial attention on the detectability of gratings of different spatial frequency was measured using a probe technique. Three experiments are reported in which the detectability of full-field probe gratings was measured while subjects analyzed stimuli presented in either the central or the peripheral visual field.
G L, Shulman, J, Wilson
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Spatial-Frequency Adaptation and Afterimages

Perception, 1977
The contribution of afterimages to spatial-frequency adaptation was studied by comparing a number of different fixation paradigms designed to maximize or minimize afterimages. While it is clear that adaptation is not an afterimage artifact, nevertheless afterimages are produced at low spatial frequencies and can considerably distort the results of ...
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