Optical ranked-order filtering using threshold decomposition
US4949389A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 9, 1987 |
| Grant date | Aug 14, 1990 |
| Priority date | — |
| Expiry date | Oct 9, 2007 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03H2001/0066
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A hybrid optical/electronic system performs median filtering and related ranked-order operations using threshold decomposition to encode the image. Threshold decomposition transforms the nonlinear neighborhood ranking operation into a linear space-invariant filtering step followed by a point-to-point threshold comparison step. Spatial multiplexing allows parallel processing of all the threshold components as well as recombination by a second linear, space-invariant filtering step. An incoherent optical correlation system performs the linear filtering, using a magneto-optic spatial light modulator as the input device and a computer-generated hologram in the filter plane. Thresholding is done electronically. By adjusting the value of the threshold, the same architecture is used to perform median, minimum, and maximum filtering of images. A totally optical system is also disclosed.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.