Contrast (vision)

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

The hot fringes of consciousness: Perceptual fluency and affect

Abstract: High figure-ground contrast usually results in more positive evaluations of visual stimuli. This may either reflect that high figure-ground contrast per se is a desirable attribute or that this attribute facilitates fluent processing. In the latter case, the influence of high figure-ground contrast should be most pronounced under short exposure times, that is, under conditions where the facilitative influence on perceptual fluency is most pronounced. Supporting this hypothesis, ratings of the prettiness of visual stimuli increased with figure-ground contrast under short exposure times (.3, 1, and 3 seconds, respectively). This positive influence of figure-ground contrast was eliminated under an exposure time of 10 seconds. We conclude that stimuli with high figure-ground contrast are more appealing because they are easier to process, not because high figure-ground contrast per se is a desirable attribute. We discuss this finding in the context of William James’ notion that the fringe of consciousness includes vague contextual feelings at the periphery of the focus of attention and suggest that perceptual fluency is one of these feelings.

Method, apparatus and recording medium for image processing

Abstract: The sense of contrast perceived by a viewer of an image is quantified and adequate image processing is carried out on image data based on the sense of contrast. Contrast-sense quantification means generates unsharp image data of the image data and then generates a histogram of the unsharp image data. Since the histogram of the image data includes lightness information of details of the image, a distribution width thereof does not represent the contrast perceived by the viewer of the image as a whole. However, since the histogram of the unsharp image data excludes information of the details, a distribution width of the unsharp image data represents the contrast of the overall image. The distribution width of the histogram of the unsharp image data is found as the sense of contrast and input to processing means. In the processing means, tone conversion processing is carried out on the image data by changing a tone conversion LUT based on the sense of contrast, and processed image data are obtained.

Mesopic contrast sensitivity in the presence or absence of glare in a large driver population

Abstract: To evaluate mesopic contrast sensitivity in conditions of glare and no glare in a vehicle driver population, and to explore the effects of age, habitual spectacle correction, photopic visual acuity and driving exposure. A cross-sectional study was performed on 297 drivers stratified by age into six groups. The mesopic contrast sensitivity was measured in the absence or presence of glare using the Mesotest II (Oculus, Germany) in each subject both with habitual and best spectacle correction. A questionnaire on the subject’s driving habits was completed. There were no significant differences between contrast sensitivity measured with habitual or best spectacle correction. In conditions of no glare, the mesopic contrast sensitivity gradually got worse from 51 to 60 years onwards, and from 41 to 50 years onwards in the presence of glare. In both conditions, the total decrease in contrast sensitivity was 0.3 log units. The with-glare and without-glare mesopic contrast sensitivity improved as photopic visual acuity increased. Forty-five per cent of drivers who reported difficulties in driving at night were unable to perform any of the tests with glare, compared to 20% without glare. However, the effect of driving habits on contrast sensitivity was only significant in the oldest age group. The mesopic contrast sensitivity and glare sensitivity seem to be stable until the age of 50 years, from which point they start to decline at a rate of 0.1 log contrast sensitivity loss per decade. Drivers with poor visual acuity and/or older drivers who avoided night driving presented worse mesopic contrast sensitivity and greater glare sensitivity.

Contrast sensitivity and the detection of moving patterns and features.

Abstract: Theories based on optimal sampling by the retina have been widely applied to visual ecology at the level of the optics of the eye, supported by visual behaviour. This leads to speculation about the additional processing that must lie in between—in the brain itself. But fewer studies have adopted a quantitative approach to evaluating the detectability of specific features in these neural pathways. We briefly review this approach with a focus on contrast sensitivity of two parallel pathways for motion processing in insects, one used for analysis of wide-field optic flow, the other for detection of small features. We further use a combination of optical modelling of image blur and physiological recording from both photoreceptors and higher-order small target motion detector neurons sensitive to small targets to show that such neurons operate right at the limits imposed by the optics of the eye and the noise level of single photoreceptors. Despite this, and the limitation of only being able to use information from adjacent receptors to detect target motion, they achieve a contrast sensitivity that rivals that of wide-field motion sensitive pathways in either insects or vertebrates—among the highest in absolute terms seen in any animal.