Document Detail

Contrast detection in luminance and chromatic noise.
MedLine Citation:
PMID:  1432339     Owner:  NLM     Status:  MEDLINE    
We measured detection thresholds for a vertically oriented 1.2-cycle-per-degree sine-wave grating embedded in spatiotemporal broadband noise. Noise and signal were modulated in different directions in color space around an equal-energy white point. When signal and noise were modulated in the same direction, we observed a linear relationship between noise spectral density and signal energy at threshold. The slope of this function was the same whether the modulation was along a luminance axis or a red-green axis. If the signal was on one axis and the noise was on the other, no masking was observed. These results support the notion of two independent and equally efficient mechanisms tuned to these directions. We then measured threshold elevations for masks with both chromatic and luminance components. When signal and noise were modulated along the same line (for example, bright red and dark green), thresholds were elevated. When we inverted the phase of the chromatic component of the noise relative to the luminance component (bright green and dark red), the masking effect disappeared, even though the amount of noise in the putative luminance and chromatic mechanisms was exactly the same as before. This implies that detection performance is limited by mechanisms sensitive to both luminance and chromatic contrast signals. We characterized these mechanisms by their spectral tuning curves.
K R Gegenfurtner; D C Kiper
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, Non-P.H.S.; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of the Optical Society of America. A, Optics and image science     Volume:  9     ISSN:  0740-3232     ISO Abbreviation:  J Opt Soc Am A     Publication Date:  1992 Nov 
Date Detail:
Created Date:  1992-12-04     Completed Date:  1992-12-04     Revised Date:  2007-11-14    
Medline Journal Info:
Nlm Unique ID:  8402086     Medline TA:  J Opt Soc Am A     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  1880-8     Citation Subset:  IM    
Howard Hughes Medical Institute, New York University, New York 10003.
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MeSH Terms
Color Perception / physiology*
Contrast Sensitivity / physiology*
Perceptual Masking*
Sensory Thresholds
Grant Support

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

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