Footsteps and Inchworms: Illusions Show That Contrast Affects Apparent Speed

A horizontal grey bar that drifts horizontally across a surround of black and white vertical stripes appears to stop and start as it crosses each stripe. A dark bar appears to slow down on a black stripe, where its edges have low contrast, and to accelerate on a white stripe, where its edges have high contrast. A light-grey bar appears to slow down on a white stripe and to accelerate on a black stripe. If the background luminances at the leading and trailing edges of the moving bar are the same, the bar appears to change speed, and if they are different the bar appears to change in length. A plaid surround can induce 2-D illusions that modulate the apparent direction, not just the speed, of moving squares. Thus, the motion salience of a moving edge depends critically on its instantaneous contrast against the background.

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Style

Presenting Science ◽

10.1093/oso/9780199549085.003.0008 ◽

2009 ◽

Author(s):

Cigdem Issever ◽

Ken Peach

Keyword(s):

Working Group ◽

Moving Objects ◽

Group Meeting ◽

High Contrast ◽

Low Contrast ◽

Dark Background ◽

Black And White ◽

Conscious Decision ◽

Colour Theory ◽

Working Group Meeting

The style of the talk should be chosen such that it supports the message, the occasion and your personality. The guiding rule should always be that the chosen style should not make the slides hard to read or distract the attention of the audience from the message. For example having an animation on the slide which runs all the time will most certainly catch the eye of the audience, because our eyes are programmed to look at moving objects. But this will make it impossible for the listener to follow your discussion on the rest of your slide while this animation is running. You can have different styles for different occasions. Figure 5.1 shows an example of a slide style for a working group meeting and in Fig. 5.2 for an invited seminar talk on the same topic. Style features which are important are the font style, the slide background and border, colours, plots, tables, pictures and animation. We will cover each of these in the sections below. The choice of the font should be a conscious decision and should not be just guided by your aesthetic feelings or the system default. There are several choices to be made under the font banner, and all are important. • Style: Serif or Sans Serif, • Appearance: normal, bold, italic, underlined or combined, • Size: small (8 pt), medium (12 pt), large (16 pt), huge (20 pt), vast (24 pt), • Colour: foreground (text) and background. Colour theory is quite complex, and beyond the scope of this book. However, a few simple ideas should help avoid most problems. The colour of the font and the colour of the background need to be considered together; it is better to choose colours that are readily distinguishable, with high contrast. A yellow (black) text on a white (dark) background is nearly invisible. Remember that your presentation may be printed on a black and white printer and colour-coded information may be lost if there is low contrast, and that between 5% and 8% of males and less than 1% of females are colour blind.

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Necker Cube Reversal: Sensory or Psychological Satiation?

Perceptual and Motor Skills ◽

10.2466/pms.1976.43.1.3 ◽

1976 ◽

Vol 43 (1) ◽

pp. 3-10 ◽

Cited By ~ 12

Author(s):

Henry G. Cornwell

Keyword(s):

Factorial Design ◽

Contrast Effect ◽

Repeated Measures ◽

Necker Cube ◽

Reversal Rate ◽

High Contrast ◽

Low Contrast ◽

Black And White ◽

High Figure

24 students, 5 male and 19 female, were used in a repeated-measures factorial design to test two theories of Necker cube reversal. It was hypothesized that cubes with complete contours and high figure-ground contrast would reverse at faster rates than cubes with incomplete contours and low contrast if a sensory satiation theory (Köhler & Wallach, 1944) is valid, but at the same rate if the satiation of an orientation theory (Orbach, Ehrlich, & Heath, 1963) is correct. High contrast was achieved with black contours on white grounds and vice versa, low contrast with gray contours on black and white grounds. Cubes with complete contours, and stimuli in which only the eight corners of the cube were visible through 18-mm holes superimposed upon the complete cube, provided the contour variable. The results showed a higher reversal rate for cubes with complete contours but no contrast effect. The results were interpreted as supporting a sensory satiation theory.

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Resistance Monitor and Control for Vacuum Evaporation of Metals and Carbon

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100092827 ◽

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.

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

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18157876 ◽

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.

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Adaptive Integration in the Visual Cortex by Depressing Recurrent Cortical Circuits

Neural Computation ◽

10.1162/neco.2008.06-07-546 ◽

2008 ◽

Vol 20 (7) ◽

pp. 1847-1872 ◽

Cited By ~ 24

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.

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

Medical Physics ◽

10.1002/mp.12224 ◽

2017 ◽

Vol 44 (9) ◽

pp. e153-e163 ◽

Cited By ~ 9

Author(s):

Damien Racine ◽

Anaïs Viry ◽

Fabio Becce ◽

Sabine Schmidt ◽

Alexandre Ba ◽

...

Keyword(s):

Spatial Resolution ◽

High Contrast ◽

Clinical Protocols ◽

Low Contrast ◽

Ct Scanners

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

Color and Imaging Conference ◽

10.2352/issn.2169-2629.2021.29.83 ◽

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.

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A Study of the Effect of Standard Laboratory Processing on Speed and Resolution of Three Black and White Aerial Films

The Canadian Surveyor ◽

10.1139/tcs-1983-0001 ◽

1983 ◽

Vol 37 (1) ◽

pp. 3-10

Author(s):

E. A. Fleming ◽

M. Landreville ◽

E. Nagy

Keyword(s):

Type A ◽

The Other ◽

Small Scale ◽

High Contrast ◽

Aerial Photo ◽

Standard Laboratory ◽

Average Gradient ◽

Black And White ◽

Contrast Range ◽

Film Speed

Three aerial films were tested using standard aerial photo laboratory processing procedures for three different chemistries. Relationships were established with respect to average gradient, speed, base plus fog, graininess and resolution for low, medium and high contrast targets. The films compared were Kodak Double-X type 2405, Kodak Plus-X type 2402 and Kodak Panatomic-X 2412. The processing was done in a Kodak Versamat processor using Type A, 885 and Versaflo chemistry. The results indicated that processing in 885 chemistry enhanced film speed. The versatility of Double-X in terms of speed and contrast range was demonstrated, however the resolution of Panatomic-X greatly exceeded that of either of the other two films and shows promise for small scale mapping photography.

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Dynamic shifts of the contrast-response function

Visual Neuroscience ◽

10.1017/s0952523800012232 ◽

1997 ◽

Vol 14 (3) ◽

pp. 577-587 ◽

Cited By ~ 10

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.

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