Contrast (vision)

About: Contrast (vision) is a research topic. Over the lifetime, 10379 publications have been published within this topic receiving 221480 citations.

Automatic contrast control for liquid crystal displays

Abstract: An LCD with automatic contrast control is provided. A light sensor is mounted over a test pixel which is separate form the main viewing area of the LCD for taking luminance measurements for "ON", "OFF", and "surround" pixel states for a series of candidate operating voltages. The pixel contrast ratio and background contrast ratio are computed for each candidate voltage and the voltage resulting in the best contrast is selected as the operating voltage for the entire LCD.

Clinical suppression and amblyopia.

Abstract: In individuals with abnormal binocular vision, such as strabismics and anisometropes, it is common for all or part of one eye's view to be suppressed so binocular confusion and diplopia are eliminated. We examined the relation between the depth of suppression (the amount by which the monocular contrast increment threshold for an eye was elevated by stimulation in the contralateral eye) and the degree of amblyopia (difference in monocular contrast thresholds for the two eyes). There was a significant negative correlation between suppression and amblyopia, so that clinical suppressors with no amblyopia exhibited deep suppression (ie, large threshold elevation) while observers with amblyopia exhibited weaker or no suppression. This negative correlation was found when the two eyes viewed orthogonally oriented contours as well as identically oriented contours. These results suggest that when an eye is amblyopic there is no longer a need for strong suppression of that eye by the contralateral eye.

The effect of early cataracts on glare and contrast sensitivity. A pilot study.

Abstract: • To establish the effect of cataracts on glare and contrast sensitivity, we graded type and amount of lens opacity in 110 subjects who underwent two glare tests (Brightness Acuity Tester and Berkeley glare test) and two contrast sensitivity tests (a sine-wave test and Pelli-Robson chart). Twenty-seven subjects (25%) had clear lenses (mean visual acuity of 20/20) and 83 subjects (75%) had early lens opacities (mean visual acuity of 20/40) in otherwise normal eyes. Multiple regression techniques were used to control for the effects of age and visual acuity. Glare test scores were significantly lower for nearly all patients with lens opacities than for patients with clear lenses and were the lowest for patients with lenses with posterior subcapsular opacity. Contrast sensitivity scores were lower for all patients with lens opacities than for patients with clear lenses at high frequencies only; all lens opacity groups scored similarly with each other. These results indicate reduced visual function among patients with cataracts whose visual acuity is only minimally impaired.

Transfer of Spatial Chromaticity-Contrast at Threshold in the Human Eye*

Abstract: Color-discrimination data are compared with the predictions of a generalized fluctuation theory for visual threshold behavior. Our observations for the tritanopic component of vision at low luminances are in good agreement with the expectations from this theory. We measured just-noticeable differences of hue with equiluminous square-wave test objects, which were modulated only in chromaticity. A chromaticity-contrast sensitivity function was introduced for the description of these results, in analogy of the luminance-contrast sensitivity function. Observations were made for different spatial frequencies at four reference wavelengths and at several luminance levels. The results do not show an attenuation of the low frequencies such as appears in the luminance-threshold contrast modulation. We infer from this that spatial interactions are different in the chromaticness and brightness channels of the visual system. Furthermore a decrease of the luminance level causes an increase of the neural integrative interaction of the color signals. We divided the measured chromaticity-contrast sensitivity function into an optical and a nervous component. A calculation for the optical part is given.