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Proceedings Paper

Simultaneous blur contrast
Author(s): Shernaaz M. Webster; Michael A. Webster; John Taylor; Jaikishan Jaikumar; Richa Verma
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Paper Abstract

How well-focused an image appears can be strongly influenced by the surroundings context. A blurred surround can cause a central image to appear too sharp, while sharped surrounds can induce blur. We examined some spatial properties and stimulus selectivities of this 'simultaneous blur contrast.' Observers adjusted the focus of a central test image by a 2AFC staircase procedure that varied the slope of the image amplitude spectrum. The test were surrounded by 8 identical images with biased spectra, that were presented concurrently with the test for 0.5 sec on a uniform gray background. Contrast effects were comparable in magnitude for image sizes ranging from 1-deg to 4-deg in visual angle, but were stronger for test that were viwe4 in the periphery rather than fixated directly. Consistent biases were found for different types of grayscale images, including natural images, filtered noise, and simple edges. However, effects were weaker when surrounds and tests were drawn from different images, or differed in contrast-polarity or color, and thus do not depend on blur or on average spatial- frequency content per se. These induction effects may in part reflect a manifestation of selective contrast gain control

Paper Details

Date Published: 8 June 2001
PDF: 9 pages
Proc. SPIE 4299, Human Vision and Electronic Imaging VI, (8 June 2001); doi: 10.1117/12.429511
Show Author Affiliations
Shernaaz M. Webster, Univ. of Nevada/Reno (United States)
Michael A. Webster, Univ. of Nevada/Reno (United States)
John Taylor, Univ. of Nevada/Reno (United States)
Jaikishan Jaikumar, Medical Research Foundation (India)
Richa Verma, Medical Research Foundation (India)


Published in SPIE Proceedings Vol. 4299:
Human Vision and Electronic Imaging VI
Bernice E. Rogowitz; Thrasyvoulos N. Pappas, Editor(s)

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