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US4097898A
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Method and apparatus for linearly filtering two-dimensional signals
Assignee: Optische Industrie de Oude Delft NV
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Filing: 1976-12-30
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Granted: 1978-06-27
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Expires: 1996-12-30
Abstract
Abstract A method of linearly filtering spatially two-dimensional signals. The signal to be filtered is applied to an electronic imaging system. For providing a scanning movement, the signal is deflected in the electronic imaging system and swept over at least one mask in which a desired corrective filter function is established in the form of a specific transmission characteristic. The light passed by the mask is detected by means of at least one photodetector placed behind the mask. The output signal of the photodetector is a representation of the filtered two-dimensional signal as a function of the time.
Inventors
- 👤 Ronald Jan Geluk
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 23:38
CPC Classifications
G; G02; G02B; G02B26/00; G02B26/08; G02B26/10; G02B26/103; G02B27/00; G02B27/58; G06; G06E; G06E3/00; G06E3/001; G06V; G06V10/00; G06V10/88
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
110 words
A method of linearly filtering spatially a two-dimensional image comprising applying the two-dimensional image to an electronic image scanning system to generate a scanned image; dividing the scanned image into two scanned image portions; filtering the separate scanning image portions by two masks, respectively, one mask including the positive part of a desired filter function and the other mask including the negative part of a desired filter function; detecting the light passed through the masks by respective photodetectors to generate respective output signals; substracting one of the output signals from the other output signal to thereby generate a filtered signal; and reproducing the filtered signal into a filtered two-dimensional image.
Claim 2
Independent Claim
110 words
A method of linearly filtering spatially a two-dimensional image comprising applying the two-dimensional image to an electronic image scanning system to generate a scanned image; dividing the scanned image into two scanned image portions; filtering the separate scanning image portions by two masks, respectively, one mask including the positive part of a desired filter function and the other mask including the negative part of a desired filter function; detecting the light passed through the masks by respective photodetectors to generate respective output signals; substracting one of the output signals from the other output signal to thereby generate a filtered signal; and reproducing the filtered signal into a filtered two-dimensional image.
Claim 3
Dependent Claim
28 words
A method as claimed in claim 1 wherein the dividing is performed by an otpical system including a beam splitter which projects respective beams on the two filters.
Claim 4
Dependent Claim
19 words
A method as claimed in claim 1 wherein the dividing is performed by an assembly of concentric light guides.
Claim 5
Independent Claim
107 words
An apparatus for linearly filtering spatially a two-dimensional image comprising electronic image scanning means for converting the two dimensional image into a scanned image; means for dividing the scanning image into two separate scanned image portions; two masks, one mask including a positive part of a filter function and the other mask including a negative part of a filter function, interposed in the respective paths of the scanned image portions; two photodetectors behind the respective two masks to sense light transmitted therethrough; and reproducing means connected to the photodetectors so that one photodetector output is substracted from the other photodetector output for generating a filtered two-dimensional image.
Claim 6
Independent Claim
107 words
An apparatus for linearly filtering spatially a two-dimensional image comprising electronic image scanning means for converting the two dimensional image into a scanned image; means for dividing the scanning image into two separate scanned image portions; two masks, one mask including a positive part of a filter function and the other mask including a negative part of a filter function, interposed in the respective paths of the scanned image portions; two photodetectors behind the respective two masks to sense light transmitted therethrough; and reproducing means connected to the photodetectors so that one photodetector output is substracted from the other photodetector output for generating a filtered two-dimensional image.
Claim 7
Dependent Claim
30 words
An apparatus as claimed in claim 4 wherein the dividing means includes an optical system with a beam splitter for projecting the two scanned image portions on the respective masks.
Claim 8
Dependent Claim
13 words
An apparatus as claimed in claim 4 wherein the photodetectors are photomultiplier tubes.
Claim 9
Dependent Claim
26 words
An apparatus as claimed in claim 4 wherein the dividing means includes an assembly of light guides having different diameters and extending partly one inside another.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1981-06-26 | 1981-12-26 | 1982-06-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1985-06-26 | 1985-12-26 | 1986-06-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1989-06-26 | 1989-12-26 | 1990-06-27 | $7700.00 | Window Closed / Lapsed |