Radiant energy – Photocells; circuits and apparatus – Photocell controlled circuit
Patent
1990-11-30
1992-02-04
Nelms, David C.
Radiant energy
Photocells; circuits and apparatus
Photocell controlled circuit
250214R, H01J 4014
Patent
active
050862197
ABSTRACT:
A computer vision edge-detection circuit uses two independent resistive networks to smooth the voltages supplied by an array of logarithmic photoreceptors. The voltages on the two networks are substracted and exclusive-or circuitry is used to detect zero-crossings. In order to facilitate thresholding of the edges, an additional current is computed at each node indicating the strength of the zero-crossing. This is particularly important for robust real-world performance where there will be many small zero-crossings induced by noise. Implementation of the present invention using analog VLSI techniques makes it feasible, and, in fact, practical to provide a large plurality of such photoreceptors on a single integrated circuit chip. Such chips can provide image acquisition and edge-detection with noise elimination in one chip in real time.
REFERENCES:
patent: 3845319 (1974-10-01), Walter
patent: 4142105 (1979-02-01), Erdmann
patent: 4697088 (1987-07-01), Bishop
Mead, Carver, Analog VLSI and Neural Systems, N.Y. Addison-Wesley, 1989, pp. 69-84, 88-89, 99, 116-121, 123-124, 260-261, 272-275, 277-278, 339-351.
Bair Wyeth
Koch Christof
California Institute of Technology
Lee John R.
Nelms David C.
Tachner Leonard
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