Xerography as a Model of the Visual System

1969 ◽  
Vol 29 (2) ◽  
pp. 543-545
Author(s):  
Willard L. Brigner
Keyword(s):  
Visual System ◽  
Brightness Contrast ◽  
Simultaneous Brightness Contrast

Xerography has been suggested as a model of the perceptual processes of the visual system. The adequacy of the model was tested in two areas, simultaneous brightness contrast and geometric illusions. Results fail to support the model.

Illusory Reversal of Brightness Contrast

1968 ◽  
Vol 27 (3_suppl) ◽  
pp. 1169-1170 ◽  
Author(s):  
Whitman Richards
Keyword(s):  
Visual System ◽  
Visual Angle ◽  
Low Frequency ◽  
Brightness Contrast ◽  
Linear Behavior ◽  
Non Linear

An illusion analogous to Cornsweet's is used to demonstrate how the non-linear behavior of the visual system can be used to obscure low-frequency gradients. The result is a reversal of brightness—from light to dark—as the visual angle of the display is changed.

Simultaneous brightness contrast in stereoscopic space

1974 ◽  
Vol 14 (10) ◽  
pp. 983-II ◽  
Author(s):  
Thomas Gibbs ◽  
R.B. Lawson
Keyword(s):  
Brightness Contrast ◽  
Simultaneous Brightness Contrast

The influence of stimulus and background colour on signal visibility in the lizard Anolis cristatellus

2001 ◽  
Vol 204 (9) ◽  
pp. 1559-1575 ◽  
Author(s):  
L.J. Fleishman ◽  
M. Persons
Keyword(s):  
Visual System ◽  
Brightness Contrast ◽  
System Response ◽  
Signal Design ◽  
Light Conditions ◽  
Chromatic Contrast ◽  
Long Wavelength ◽  
Peak Sensitivity ◽  
Multi Linear Regression ◽  
To Receive

Anoline lizards communicate with visual displays in which they open and close a colourful throat fan called the dewlap. We used a visual fixation reflex as an assay to test the effects of stimulus versus background chromatic and brightness contrast on the probability of detecting a moving coloured (i.e. dewlap-like) stimulus in Anolis cristatellus. The probability of stimulus detection depended on two additive visual-system channels, one responding to brightness contrast and one responding to chromatic contrast, independent of brightness. The brightness channel was influenced only by wavelengths longer than 450nm and probably received input only from middle- and/or long-wavelength photoreceptors. The chromatic contrast channel appeared to receive input from three, or possibly four, different classes of cone in the anoline retina, including one with peak sensitivity in the ultraviolet. We developed a multi-linear regression equation that described most of the results of this study to a reasonable degree of accuracy. In the future, this equation could be used to predict the relative visibility of different-coloured stimuli in different habitat light conditions, which should be very useful for testing hypotheses that attempt to relate habitat light conditions and visual-system response to the evolution of signal design.

scholarly journals The Additivity of Contrast in the Human Eye

1959 ◽  
Vol 43 (1) ◽  
pp. 109-126 ◽  
Author(s):  
Mathew Alpern ◽  
Herbert David
Keyword(s):  
Brightness Contrast ◽  
Contrast Effects ◽  
Test Patch ◽  
Human Eye ◽  
Simultaneous Brightness Contrast ◽  
Excitation State

Using the method of binocular brightness matching, simultaneous brightness contrast effects were measured on two observers. The effects of a given pattern were invariably smaller than the summation of the effects of the pattern's components. This failure of additivity was valid both for patterns with isolated components as well as for those with components exactly contiguous with one another. This failure was more pronounced the farther the inducing patterns were from the test patch. These findings are interpreted as indicating that in the human (just as in the Limulus) eye, the amount of inhibition exerted by a given region on its neighbors depends upon the inhibition exerted against it as well as its excitation state.

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