A Variant of the Anomalous Motion Illusion Based upon Contrast and Visual Latency

Perception ◽  
10.1068/p5362 ◽  
2007 ◽  
Vol 36 (7) ◽  
pp. 1019-1035 ◽  
Author(s):  
Akiyoshi Kitaoka ◽  
Hiroshi Ashida
Keyword(s):  
Critical Factor ◽  
Luminance Contrast ◽  
High Contrast ◽  
Illusory Motion ◽  
Low Contrast ◽  
Motion In Depth ◽  
Contrast Pattern ◽  
Pulfrich Effect ◽  
Series Of Experiments ◽  
Visual Delay

We examined a variant of the anomalous motion illusion. In a series of experiments, we ascertained luminance contrast to be the critical factor. Low-contrast random dots showed longer latency than high-contrast ones, irrespective of whether they were dark or light (experiments 1–3). We conjecture that this illusion may share the same mechanism with the Hess effect, which is characterised by visual delay of a low-contrast, dark stimulus in a moving situation. Since the Hess effect is known as the monocular version of the Pulfrich effect, we examined whether illusory motion in depth could be observed if a high-contrast pattern was projected to one eye and the same pattern of low-contrast was presented to the other eye, and they were binocularly fused and swayed horizontally. Observers then reported illusory motion in depth when the low-contrast pattern was dark, but they did not when it was bright (experiment 4). Possible explanations of this inconsistency are discussed.

Visual thresholds to low-contrast pattern displacement, color contrast, and luminance contrast stimuli in Parkinson's disease

1994 ◽  
Vol 9 (5) ◽  
pp. 563-570 ◽  
Author(s):  
Bernhard A. Haug ◽  
Claudia Trenkwalder ◽  
Geoffrey B. Arden ◽  
Wolfgang H. Oertel ◽  
Walter Paulus
Keyword(s):  
Parkinson’S Disease ◽  
Parkinson's Disease ◽  
Luminance Contrast ◽  
Color Contrast ◽  
Low Contrast ◽  
Contrast Pattern

Resistance Monitor and Control for Vacuum Evaporation of Metals and Carbon

1976 ◽  
Vol 34 ◽  
pp. 572-573
Author(s):  
Russell L. Steere ◽  
Eric F. Erbe ◽  
J. Michael Moseley
Keyword(s):  
Electronic Device ◽  
Point Sources ◽  
High Contrast ◽  
Variable Resistor ◽  
Quality Of Results ◽  
Low Contrast ◽  
Evaporation Source ◽  
And Control ◽  
At Will

We have designed and built an electronic device which compares the resistance of a defined area of vacuum evaporated material with a variable resistor. When the two resistances are matched, the device automatically disconnects the primary side of the substrate transformer and stops further evaporation.This approach to controlled evaporation in conjunction with the modified guns and evaporation source permits reliably reproducible multiple Pt shadow films from a single Pt wrapped carbon point source. The reproducibility from consecutive C point sources is also reliable. Furthermore, the device we have developed permits us to select a predetermined resistance so that low contrast high-resolution shadows, heavy high contrast shadows, or any grade in between can be selected at will. The reproducibility and quality of results are demonstrated in Figures 1-4 which represent evaporations at various settings of the variable resistor.

scholarly journals Minimum Detectable Change of Visual Acuity Measurements Using ETDRS Charts (Early Treatment Diabetic Retinopathy Study)

2021 ◽  
Vol 18 (15) ◽  
pp. 7876
Author(s):  
María Carmen Sánchez-González ◽  
Raquel García-Oliver ◽  
José-María Sánchez-González ◽  
María-José Bautista-Llamas ◽  
José-Jesús Jiménez-Rejano ◽  
...  
Keyword(s):  
Visual Acuity ◽  
Diabetic Retinopathy ◽  
Early Treatment ◽  
High Reliability ◽  
Minimal Detectable Change ◽  
High Contrast ◽  
Detectable Change ◽  
Low Contrast ◽  
Minimum Detectable Change ◽  
The Mean

In our work, we determined the value of visual acuity (VA) with ETDRS charts (Early Treatment Diabetic Retinopathy Study). The purpose of the study was to determine the measurement reliabilities, calculating the correlation coefficient interclass (ICC), the value of the error associated with the measure (SEM), and the minimal detectable change (MDC). Forty healthy subjects took part. The mean age was 23.5 ± 3.1 (19 to 26) years. Visual acuities were measured with ETDRS charts (96% ETDRS chart nº 2140) and (10% SLOAN Contrast Eye Test chart nº 2153). The measurements were made (at 4 m) under four conditions: Firstly, photopic conditions with high contrast (HC) and low contrast (LC) and after 15 min of visual rest, mesopic conditions with high and low contrast. Under photopic conditions and high contrast, the ICC = 0.866 and decreased to 0.580 when the luminosity and contrast decreased. The % MDC in the four conditions was always less than 10%. It was minor under photopic conditions and HC (5.83) and maximum in mesopic conditions and LC (9.70). Our results conclude a high reliability of the ETDRS test, which is higher in photopic and high contrast conditions and lower when the luminosity and contrast decreases.

scholarly journals Adaptive Integration in the Visual Cortex by Depressing Recurrent Cortical Circuits

2008 ◽  
Vol 20 (7) ◽  
pp. 1847-1872 ◽  
Author(s):  
Mark C. W. van Rossum ◽  
Matthijs A. A. van der Meer ◽  
Dengke Xiao ◽  
Mike W. Oram
Keyword(s):  
Visual Cortex ◽  
Physiological Data ◽  
High Contrast ◽  
Cortical Circuits ◽  
Response Latencies ◽  
Low Contrast ◽  
Visual Areas ◽  
Higher Visual Areas ◽  
Recurrent Connections

Neurons in the visual cortex receive a large amount of input from recurrent connections, yet the functional role of these connections remains unclear. Here we explore networks with strong recurrence in a computational model and show that short-term depression of the synapses in the recurrent loops implements an adaptive filter. This allows the visual system to respond reliably to deteriorated stimuli yet quickly to high-quality stimuli. For low-contrast stimuli, the model predicts long response latencies, whereas latencies are short for high-contrast stimuli. This is consistent with physiological data showing that in higher visual areas, latencies can increase more than 100 ms at low contrast compared to high contrast. Moreover, when presented with briefly flashed stimuli, the model predicts stereotypical responses that outlast the stimulus, again consistent with physiological findings. The adaptive properties of the model suggest that the abundant recurrent connections found in visual cortex serve to adapt the network's time constant in accordance with the stimulus and normalizes neuronal signals such that processing is as fast as possible while maintaining reliability.

scholarly journals Objective comparison of high-contrast spatial resolution and low-contrast detectability for various clinical protocols on multiple CT scanners

2017 ◽  
Vol 44 (9) ◽  
pp. e153-e163 ◽  
Author(s):  
Damien Racine ◽  
Anaïs Viry ◽  
Fabio Becce ◽  
Sabine Schmidt ◽  
Alexandre Ba ◽  
...  
Keyword(s):  
Spatial Resolution ◽  
High Contrast ◽  
Clinical Protocols ◽  
Low Contrast ◽  
Ct Scanners

How Good is Too Good? A Subjective Study on Over Enhancement of Images

2021 ◽  
Vol 2021 (29) ◽  
pp. 83-88
Author(s):  
Sahar Azimian ◽  
Farah Torkamani Azar ◽  
Seyed Ali Amirshahi
Keyword(s):  
Image Quality ◽  
High Contrast ◽  
Current Image ◽  
Low Contrast ◽  
Image Dataset ◽  
Long Time ◽  
Reference Images ◽  
Subjective Study ◽  
Contrast Image

For a long time different studies have focused on introducing new image enhancement techniques. While these techniques show a good performance and are able to increase the quality of images, little attention has been paid to how and when overenhancement occurs in the image. This could possibly be linked to the fact that current image quality metrics are not able to accurately evaluate the quality of enhanced images. In this study we introduce the Subjective Enhanced Image Dataset (SEID) in which 15 observers are asked to enhance the quality of 30 reference images which are shown to them once at a low and another time at a high contrast. Observers were instructed to enhance the quality of the images to the point that any more enhancement will result in a drop in the image quality. Results show that there is an agreement between observers on when over-enhancement occurs and this point is closely similar no matter if the high contrast or the low contrast image is enhanced.

Dynamic shifts of the contrast-response function

1997 ◽  
Vol 14 (3) ◽  
pp. 577-587 ◽  
Author(s):  
Jonathan D. Victor ◽  
Mary M. Conte ◽  
Keith P. Purpura
Keyword(s):  
Gain Control ◽  
Human Vision ◽  
High Contrast ◽  
Contrast Level ◽  
Low Contrast ◽  
Contrast Gain ◽  
Contrast Response Function ◽  
Stimuli Response ◽  
Response Phase ◽  
Contrast Response

AbstractWe recorded visual evoked potentials in response to square-wave contrast-reversal checkerboards undergoing a transition in the mean contrast level. Checkerboards were modulated at 4.22 Hz (8.45-Hz reversal rate). After each set of 16 cycles of reversals, stimulus contrast abruptly switched between a “high” contrast level (0.06 to 1.0) to a “low” contrast level (0.03 to 0.5). Higher contrasts attenuated responses to lower contrasts by up to a factor of 2 during the period immediately following the contrast change. Contrast-response functions derived from the initial second following a conditioning contrast shifted by a factor of 2–4 along the contrast axis. For low-contrast stimuli, response phase was an advancing function of the contrast level in the immediately preceding second. For high-contrast stimuli, response phase was independent of the prior contrast history. Steady stimulation for periods as long as 1 min produced only minor effects on response amplitude, and no detectable effects on response phase. These observations delineate the dynamics of a contrast gain control in human vision.

scholarly journals Outline and surface disruption in animal camouflage

2008 ◽  
Vol 276 (1657) ◽  
pp. 781-786 ◽  
Author(s):  
Martin Stevens ◽  
Isabel S Winney ◽  
Abi Cantor ◽  
Julia Graham
Keyword(s):  
Body Shape ◽  
Luminance Contrast ◽  
The Body ◽  
Maximum Effect ◽  
High Contrast ◽  
High Luminance ◽  
Effective Surface ◽  
Avian Predators ◽  
Disruptive Coloration ◽  
Visual Mechanism

Camouflage is an important strategy in animals to prevent predation. This includes disruptive coloration, where high-contrast markings placed at an animal's edge break up the true body shape. Successful disruption may also involve non-marginal markings found away from the body outline that create ‘false edges’ more salient than the true body form (‘surface disruption’). However, previous work has focused on breaking up the true body outline, not on surface disruption. Furthermore, while high contrast may enhance disruption, it is untested where on the body different contrasts should be placed for maximum effect. We used artificial prey presented to wild avian predators in the field, to determine the effectiveness of surface disruption, and of different luminance contrast placed in different prey locations. Disruptive coloration was no more effective when comprising high luminance contrast per se , but its effectiveness was dramatically increased with high-contrast markings placed away from the body outline, creating effective surface disruption. A model of avian visual edge processing showed that surface disruption does not make object detection more difficult simply by creating false edges away from the true body outline, but its effect may also be based on a different visual mechanism. Our study has implications for whether animals can combine disruptive coloration with other ‘conspicuous’ signalling strategies.

A triphenylamine-based benzoxazole derivative as a high-contrast piezofluorochromic material induced by protonation

2014 ◽  
Vol 50 (20) ◽  
pp. 2569-2571 ◽  
Author(s):  
Pengchong Xue ◽  
Peng Chen ◽  
Junhui Jia ◽  
Qiuxia Xu ◽  
Jiabao Sun ◽  
...  
Keyword(s):  
Red Shift ◽  
High Contrast ◽  
Low Contrast

A triphenylamine-based benzoxazole derivative (BVDP) as a typical D–π–A molecule could be used as a low contrast piezofluorochromic material with a spectral red-shift of 29 nm. However, whenBVDPbound a proton to formBVDP+H, a high contrast piezofluorochromism (Δλ= 75 nm) could be observed.

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