Results 261 to 270 of about 320,340 (290)

Polarization Contrast Vision in Octopus

Journal of Experimental Biology, 1996
ABSTRACT While the ability to analyze polarized light is widespread among animals, its contribution to form vision has not yet been documented. We tested the hypothesis that polarization vision can be used for object discrimination, by training octopuses to distinguish between targets on the basis of the presence or absence of a pattern ...
N, Shashar, T W, Cronin
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[Experience in contrast vision testing].

Klinische Monatsblatter fur Augenheilkunde, 2012
Since July 2011 driving licensing in Germany requires contrast vision to be tested. Recommendations are available for testing under mesopic conditions only. This study is aimed to provide recommendations for photopic testing.169 persons were tested both under mesopic (Mesotest) and photopic (Optovist) conditions.With the Mesotest the setting without ...
H, Wilhelm, D, Hofmann, S, Roelcke, R, Quast   +3 more
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Vision channels, contrast sensitivity, and functional vision

SPIE Proceedings, 2004
The neurophysiology and psychophysics of vision provide the basis for vision channels. Vision channels are the foundation of understanding spatial vision. This understanding has led to the development of a general model of visual perception and tests of functional vision.
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Characteristic of Contrast Vision

1987
Six typical threshold contrast-sensitivity functions, frequently found in our ophthalmological practice, are analyzed, using the concept of spatial filtering in order to understand how we see the everyday world in the case of normal and abnormal vision.
Maria L. F. De Mattiello, Alejandro Gonella, Ernesto Mazzeo   +2 more
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Spatial Vision and Aging. I: Contrast Sensitivity

Journal of Gerontology, 1980
Contrast sensitivity functions (CSFs) were measured for two groups of healthy observers, a younger group with mean age 18.5 years and an older group with mean age 73 years. Although the two groups had virtually identical sensitivities to high spatial frequencies (gratings with narrow bars), the younger observers were three times more sensitive at low ...
R, Sekuler, L P, Hutman
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Insect vision: Contrast perception under fluctuating light

Current Biology, 2023
Natural light levels vary tremendously, both over the day and from minute to minute, creating a formidable challenge for animals that rely on vision to survive. New work in fruit flies demonstrates the neural mechanisms that produce luminance-invariant perceptions of visual contrast.
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Vision Evaluation Using Contrast Sensitivity Functions

Optometry and Vision Science, 1983
The use of Contrast Sensitivity Functions (CSF's) in vision evaluation has been explored for several years. Although theoretically superior to Snellen acuity and similar measures, the use of CSF is not widespread. A review of some of the clinical conditions in which CSF's have been used is followed by a discussion of the problems involved in their ...
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Temporal properties of spatial contrast vision

Vision Research, 1987
The temporal characteristics of spatial contrast vision at and above threshold were assessed psychophysically using sinusoidal gratings and a contrast-matching method. Temporal frequency response curves became flatter as contrast level increased. An impulse response model was fitted to these flicker data, and used to make predictions about temporal ...
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Photopic contrast sensitivity without foveal vision

Optics Letters, 1978
Sine-wave contrast sensitivity is greatly reduced when the subject is prevented from using his fovea by a stabilized obscuration. For example, with a 3° obscuring stripe, his sensitivity is one third of normal. However, the foveal-deprivation effect seems to be independent of the spatial frequency of the stimulus, which provides an important constraint
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[Contrast sensitivity and vision].

Ceskoslovenska oftalmologie, 1993
From results of the contrast sensitivity test (n = 65, r = 0.834) it is possible to estimate visual acuity with considerable provedes, however, in addition also information on vision at low contrast conditions and on vision of large objects. It may therefore be expected that in future the two-dimensional visuogram will replace in clinical practice the ...
J, Peregrin, D, Hejcmanová, J, Svĕrák
openaire   +1 more source