Document Detail

Color and luminance spatial tuning estimated by noise masking in the absence of off-frequency looking.
MedLine Citation:
PMID:  7869156     Owner:  NLM     Status:  MEDLINE    
We assessed the contribution of off-frequency looking for pattern detection and obtained bandwidths for chromatic and luminance mechanisms in conditions free from this effect. We used a simultaneous spatial masking technique with Gaussian enveloped sinusoidal test stimuli (0.5 cycle/deg) and filtered one-dimensional static-noise masks whose spectral power was uniformly distributed per octave. Stimuli were modulated in the chromatic (isoluminant red-green) or the luminance (yellow-black) domain. Color and luminance detection thresholds were compared for low-pass, high-pass, and notch- (band-stopped) filtered noise. We obtained the following results: (1) at high-noise spectral densities, masking by notched noise is greater than the summed masking of the high- and low-pass noise, indicating the presence of off-frequency looking for both color and luminance detection. There is no evidence for off-frequency looking at lower power densities. (2) Using notch-filtered noise, which avoids the problem of off-frequency looking, we found that color processing is subserved by bandpass channels with bandwidths similar to those revealed for luminance processing. (3) Both color and luminance mechanisms appear to have bandwidths proportional to their center frequency (constant in octaves). (4) The lower and upper sides of the color and luminance tuning functions were estimated individually by use of high-pass and low-pass noise of a low power density and are revealed to be asymmetric, with the lower side declining more steeply than the upper side.
M A Losada; K T Mullen
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of the Optical Society of America. A, Optics, image science, and vision     Volume:  12     ISSN:  1084-7529     ISO Abbreviation:  J Opt Soc Am A Opt Image Sci Vis     Publication Date:  1995 Feb 
Date Detail:
Created Date:  1995-03-27     Completed Date:  1995-03-27     Revised Date:  2006-11-15    
Medline Journal Info:
Nlm Unique ID:  9800943     Medline TA:  J Opt Soc Am A Opt Image Sci Vis     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  250-60     Citation Subset:  IM    
McGill Vision Research, Department of Ophthalmology, McGill University, Montreal, Canada.
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MeSH Terms
Color Perception / physiology*
Pattern Recognition, Visual / physiology
Sensory Thresholds / physiology

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

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