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Proceedings Paper

Implementing early visual processing in analog VLSI: light adaptation
Author(s): James Mann
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Paper Abstract

A circuit which emulates the functioning of cone photoreceptors in the vertebrate retina has been designed and tested. Cone photoreceptors exhibit a local adaptation to background illumination over many orders of magnitude while retaining a high degree of instantaneous contrast sensitivity. This behavior permits visual discrimination of objects against difficult lighting situations such as bright backgrounds. This effort includes an examination of the trade-offs in various photodetection techniques available to the designer in silicon. Photodetection is followed by separate filter and gain stages which provide the appropriate temporal behavior. The filters and gain are independently tunable to permit extensions in operation to those environments which may fall outside the capability of human vision. The circuit also includes a UV writable floating gate which uses a locally generated error signal to provide cancellation of circuit offsets due to process variability.

Paper Details

Date Published: 9 July 1991
PDF: 9 pages
Proc. SPIE 1473, Visual Information Processing: From Neurons to Chips, (9 July 1991); doi: 10.1117/12.45545
Show Author Affiliations
James Mann, Lincoln Lab./MIT (United States)

Published in SPIE Proceedings Vol. 1473:
Visual Information Processing: From Neurons to Chips
Bimal P. Mathur; Christof Koch, Editor(s)

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