Contrast (vision)

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

Contrast sensitivity in children and adults.

Abstract: Contrast sensitivity functions to vertical sinusoidal gratings have been measured in 135 subjects ranging from 3 to 29 years of age. The reported contrast sensitivities for all spatial frequencies increased steadily with age, reaching adult levels during adolescence. The usefulness of these functions as a clinical test is discussed.

What limits performance in the amblyopic visual system: seeing signals in noise with an amblyopic brain.

Abstract: Amblyopia results in a loss of visual acuity, contrast sensitivity, and position acuity. However, the nature of the neural losses is not yet fully understood. Here we report the results of experiments using noise to try to better understand the losses in amblyopia. Specifically, in one experiment we compared the performance of normal, amblyopic, and ideal observers for detecting a localized signal (a discrete frequency pattern or DFP) in fixed contrast white noise. In a second experiment, we used visibility-scaled noise and varied both the visibility of the noise (from 2 to 20 times the noise detection threshold) and the spatial frequency of the signal. Our results show a loss of efficiency for detection of known signals in noise that increases with the spatial frequency of the signal in observers with amblyopia. To determine whether the loss of efficiency was a consequence of a mismatched template, we derived classification images. We found that although the amblyopic observers' template was shifted to lower spatial frequencies, the shift was insufficient to account for their threshold elevation. Reduced efficiency in the amblyopic visual system may reflect a high level of internal noise, a poorly matched position template, or both. To analyze the type of internal noise we used an "N-pass" technique, in which observers performed the identical experiment N times (where N = 3 or 4). The amount of disagreement between the repeated trials enables us to parse the internal noise into random noise and consistent noise beyond that due to the poorly matched template. Our results show that the amblyopes' reduced efficiency for detecting signals in noise is explained in part by reduced template efficiency but to a greater extent by increased random internal noise. This loss is more or less independent of external noise contrast over a log unit range of external noise.

Method and apparatus for central visual field mapping and optimization of image presentation based upon mapped parameters

Abstract: A method and apparatus for testing individuals having a sub-optimal central field of vision so as to identify areas within the visual field in which images can be perceived and for determining effects of contrast sensitivity and distortion within such areas such that visual images may be presented, after being enhanced so as to modify the images in accordance with tested parameters, so that the individual will perceive the images in an improved manner.

Spatial contrast sensitivity. Importance of controlling the patient's visibility criterion.

Abstract: • Clinical spatial contrast sensitivity measurements are typically made using psychophysical methods that do not specify the response criterion being used by the patient in judging grating visibility. Results of this report show the necessity of such methods for (1) maximizing detectability of early contrast sensitivity deficits by minimizing normal sample variance, and (2) ensuring that changes in an individual's contrast sensitivity reflect changes in vision and not simply fluctuations in the patient's criterion for judging grating visibility.