Contrast sensitivity to radial frequencies modulated by Jn and jn Bessel profiles
Braz. j. med. biol. res
;
35(11): 1357-1366, Nov. 2002. ilus, graf
Article
in English
| LILACS
| ID: lil-326248
RESUMO
We measured human contrast sensitivity to radial frequencies modulated by cylindrical (Jo) and spherical (j o) Bessel profiles. We also measured responses to profiles of j o, j1, j2, j4, j8, and j16. Functions were measured three times by at least three of eight observers using a forced-choice method. The results conform to our expectations that sensitivity would be higher for cylindrical profiles. We also observed that contrast sensitivity is increased with the j n order for n greater than zero, having distinct orderly effects at the low and high frequency ends. For n = 0, 1, 2, and 4 sensitivity tended to occur around 0.8-1.0 cpd while for n = 8 and 16 it seemed to shift gradually to 0.8-3.0 cpd. We interpret these results as being consistent with the possibility that spatial frequency processing by the human visual system can be defined a priori in terms of polar coordinates and discuss its application to study face perception
Full text:
Available
Index:
LILACS (Americas)
Main subject:
Photic Stimulation
/
Sensory Thresholds
/
Contrast Sensitivity
Type of study:
Diagnostic study
Limits:
Adult
/
Humans
Language:
English
Journal:
Braz. j. med. biol. res
Journal subject:
Biology
/
Medicine
Year:
2002
Type:
Article
/
Congress and conference
/
Project document
Affiliation country:
Brazil
Institution/Affiliation country:
Universidade Federal de Pernambuco/BR
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