Document Detail

Spatial-frequency tuning of sustained nonoriented units of the red-green channel.
MedLine Citation:
PMID:  9459791     Owner:  NLM     Status:  MEDLINE    
The existence of nonoriented cells but not of sustained orthogonal masking for achromatic stimuli led to an investigation of the spatial-frequency (SF) tuning of sustained nonoriented color units. For this purpose the Red-Green channel was isolated by the minimum flicker and hue cancellation techniques. Chromatic contrast sensitivity functions (CSF's), threshold elevation (TE) curves, and contrast nonlinearities (TE-versus-mask-contrast curves) were measured with spatially localized vertical color tests and sinusoidal orthogonal color masks by the method of constant stimuli under Gaussian temporal presentation. Results show that (1) color CSF's are a low-pass function of SF, whereas TE curves are a bandpass function of mask SF, and (2) a minimum of six SF-tuned color mechanisms (one low pass and five bandpass functions of SF, with peak SF's of 0.13, 0.5, 2, 4, and 8 cycles per degree and bandwidths of 3.9, 4.4, 2.9, 2.1, 1.1, and 1.2 octaves), similar to oblique-masking color mechanisms, are extracted by the multiple-mechanisms model. These data imply that (1) most of the SF tuning of the broadly oriented color units is already present in the circularly symmetric units, and (2) the latter may be an input to the former.
R L Vimal
Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of the Optical Society of America. A, Optics, image science, and vision     Volume:  15     ISSN:  1084-7529     ISO Abbreviation:  J Opt Soc Am A Opt Image Sci Vis     Publication Date:  1998 Jan 
Date Detail:
Created Date:  1998-02-19     Completed Date:  1998-02-19     Revised Date:  2007-11-14    
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:  1-15     Citation Subset:  IM    
Vision Research Institute, Lexington, Massachusetts 02173, USA.
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MeSH Terms
Color Perception / physiology*
Contrast Sensitivity / physiology
Models, Biological
Perceptual Masking / physiology
Sensory Thresholds / physiology
Grant Support

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