Results 291 to 300 of about 3,408,895 (339)
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Ophthalmology, 1989
The detection of small luminance differences between objects and their backgrounds is an important tool for navigating in the visual environment. Many visual system disorders cause patients to complain that their vision is cloudy or blurred, or that the borders of objects are blurred, even though they retain 20/20 Snellen acuity.
Mark J. Kupersmith +2 more
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The detection of small luminance differences between objects and their backgrounds is an important tool for navigating in the visual environment. Many visual system disorders cause patients to complain that their vision is cloudy or blurred, or that the borders of objects are blurred, even though they retain 20/20 Snellen acuity.
Mark J. Kupersmith +2 more
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Evaluating contrast sensitivity
SPIE Proceedings, 2006The problem for proper rendering of spatial frequencies in digital imaging applications is to establish the relative contrast sensitivity of observers at suprathreshold contrast levels in typical viewing environments. In an experimental study two methods of evaluating spatial contrast sensitivity were investigated, using targets of graded tonal ...
Saori Kitaguchi +2 more
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Jogging and contrast sensitivity
Acta Ophthalmologica, 1988Abstract. Threshold contrast sensitivity was measured using sinusoidal gratings with the method of increasing contrast both before and after jogging in fresh air. The mean contrast sensitivity of 11 subjects was higher after jogging at all three spatial frequencies studied (1, 6 and 19 c/deg). The differences were statistically significant. The effect
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Contrast sensitivity in asymmetric glaucoma
International Ophthalmology, 1984We measured central contrast sensitivity in both eyes of 27 patients with asymmetric glaucomatous visual field loss or optic disc cupping. In 15 patients contrast sensitivity was less in the eye that by perimetry or ophthalmoscopy was the more severely damaged. In 10 patients contrast sensitivity was the same in the two eyes.
M A, Motolko, C D, Phelps
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Contrast sensitivity in Parkinson's disease
Neurology, 1986We studied contrast-sensitivity function in 39 patients with Parkinson's disease. Sixty-four percent of the patients showed contrast-sensitivity loss in one or both eyes. The abnormality was not related to the first symptom or the severity of disease.
C, Bulens +3 more
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Clinical contrast sensitivity chart evaluation
Ophthalmic and Physiological Optics, 1992Three different types of contrast sensitivity chart were used on normal patients by six optometrists in clinical practice. The charts were the Vistech, the Pelli ‐Robson and the Cambridge low‐contrast gratings test. We examine the data in terms of the differences between optometrists and the variation of contrast sensitivity with the age of the patient.
D B, Elliott, D, Whitaker
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1984
The contrast sensitivity function is a normalised description of a system’s sensitivity to spatial frequencies in terms of the contrast required to perform some perceptual task. For detection tasks, the human C.S.F. peaks at around 3–5 cycles/deg and reaches zero at about 60 cycles/deg. See modulation transfer function .
Alan Bundy, Lincoln Wallen
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The contrast sensitivity function is a normalised description of a system’s sensitivity to spatial frequencies in terms of the contrast required to perform some perceptual task. For detection tasks, the human C.S.F. peaks at around 3–5 cycles/deg and reaches zero at about 60 cycles/deg. See modulation transfer function .
Alan Bundy, Lincoln Wallen
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Microprocessor-controlled contrast sensitivity measurements
Medical and Biological Engineering and Computing, 1979A system is described for automatic measurement of contrast sensitivity functions (c.s.f.). The measuring technique is based on the Von Bekesy tracking method. One c.s.f. can be measured in 10 min. The stimuli (sinewave gratings) are generated on a t.v. monitor screen.
C J, Keemink +2 more
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Iodinated contrast sensitivity in ERCP
The American Journal of Gastroenterology, 2000Iodine contrast media are detectable in the bloodstream after ERCP, and sensitivity reactions have been described. The risk is very small, and the phenomenon is therefore difficult to study. This review discusses the possible need for preventative strategies, and recommends that endoscopists consider the issue and define their own policies.
P, Draganov, P B, Cotton
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