Abstract

Psychophysical evidence indicates that, in the human retina, the size of the spatial-summation area decreases as illuminance increases. Such a relationship would be beneficial for the detection of spatial contrast in the presence of photon noise. We analyze an image-processing mechanism in which the area of a strictly positive point-spread function varies inversely with local illuminance while its volume remains constant. In addition to its expected effect of improving spatial resolution as illuminance increases, this mechanism also yields center-surround antagonism and all other manifestations of bandpass filtering and accounts for Ricco’s law and Weber’s law—including the failures of both laws as a function of test conditions. The relationship between this mechanism and lateral inhibition is analyzed.

© 1985 Optical Society of America

Photon noise and constant-volume operators

John I. Yellott
J. Opt. Soc. Am. A 4(12) 2418-2446 (1987)

The area of complete scotopic spatial summation enlarges with age

Brooke E. Schefrin, Michelle L. Bieber, Ryan McLean, and John S. Werner
J. Opt. Soc. Am. A 15(2) 340-348 (1998)

Forward and inverse model for the intensity-dependent spread filter

Shahriar Najand, Douglas Blough, and Glenn Healey
J. Opt. Soc. Am. A 13(7) 1305-1314 (1996)

Spatial summation in human cone mechanisms from 0° to 20° in the superior retina

Vicki J. Volbrecht, Erin E. Shrago, Brooke E. Schefrin, and John S. Werner
J. Opt. Soc. Am. A 17(3) 641-650 (2000)

Effect of eccentricity on spatial summation and acuity

Robert A. Smith and Peter F. Cass
J. Opt. Soc. Am. A 6(10) 1633-1639 (1989)