Variance of high contrast textures is sensed using negative half-wave rectification.

Variance of high contrast textures is sensed using negative half-wave rectification.

MedLine Citation:	PMID: 10814756 Owner: NLM Status: MEDLINE
Abstract/OtherAbstract:	A rectifying transformation is required to sense variations in texture contrast. Various theoretical and practical considerations have inclined researchers to suppose that this rectification is full-wave, rather than half-wave. In the studies reported here, observers are asked to judge which of two texture patches has higher texture variance. Textures are composed of small squares, with each square being painted with one of nine different luminances. Different texture variances are achieved by manipulating the histograms of the texture patches to be compared. When the nine luminances range linearly from 0 to 160 cd/m(2), the transformation mediating judgments of texture variance takes the form of a negative half-wave rectifier: texture variance judgments are determined exclusively by the frequencies of luminances below mean luminance in the textures being compared. However, when the nine luminances range linearly from 60 to 100 cd/m(2), two of three observers use a full-wave rectifying transformation in making texture variance judgments; the third observer continued to use a negative half-wave rectifier. The unexpectedly asymmetric roles played by low versus high luminances in texture variance judgments suggest that the off-center system may play a dominant role in human perception of texture contrast.

Authors:	C Chubb; J H Nam
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Publication Detail:	Type: Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, Non-P.H.S.
Journal Detail:	Title: Vision research Volume: 40 ISSN: 0042-6989 ISO Abbreviation: Vision Res. Publication Date: 2000
Date Detail:	Created Date: 2000-08-04 Completed Date: 2000-08-04 Revised Date: 2006-11-15
Medline Journal Info:	Nlm Unique ID: 0417402 Medline TA: Vision Res Country: ENGLAND
Other Details:	Languages: eng Pagination: 1677-94 Citation Subset: IM
Affiliation:	Department of Cognitive Sciences, Institute for Mathematical Behavioral Sciences, University of California at Irvine, Irvine, CA 92697-5100, USA. cfchubb@uci.edu
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MeSH Terms
Descriptor/Qualifier:	Contrast Sensitivity / physiology* Humans Lighting Mathematical Computing*

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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