Patent US3813486A successfully refreshed from Google Patents.
US3813486A
Expired / Lapsed
US
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Image analysis
Assignee: Image Analysing Computers Ltd
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Filing: 1970-10-28
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Granted: 1974-05-28
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Expires: 1990-10-28
Abstract
Abstract The invention concerns image analysis systems employing a source of scanned video signal and threshold detector means for generating a binary signal whose value depends on the fulfilment or otherwise of the detection criterion. Means are provided for accumulating at least the low frequency content of the video signal and deriving therefrom a correcting voltage for application to the detector means to reduce variations between the peak value of the video signal corresponding to the background of the image and the threshold level of said detector means.
Inventors
- 👤 W Knowles
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 17:15
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/403; H04N5/00; H04N5/14
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
156 words
In an image analysis system employing a source of scanned video signal and threshold detector means for generating a binary signal whose value depends on the fulfillment or otherwise of the detection criterion, the improvement comprising a peak value integrating circuit having one time constant for a rising video signal and a different time constant for a falling video signal to produce a correcting voltage which is proportional to the peak of the video signal, means for supplying the correcting voltage to the detector means as the threshold voltage therefor, the variations in the correcting voltage serving to compensate for shading distortion in the video signal amplitude, means for increasing the time constant of said integrating circuit to a high value, and means for detecting the duration of an iNtersection of a line scan with a feature and for activating the means for increasing the integrating circuit time constant for the duration of each such intersection.
Claim 2
Dependent Claim
156 words
In an image analysis system employing a source of scanned video signal and threshold detector means for generating a binary signal whose value depends on the fulfillment or otherwise of the detection criterion, the improvement comprising a peak value integrating circuit having one time constant for a rising video signal and a different time constant for a falling video signal to produce a correcting voltage which is proportional to the peak of the video signal, means for supplying the correcting voltage to the detector means as the threshold voltage therefor, the variations in the correcting voltage serving to compensate for shading distortion in the video signal amplitude, means for increasing the time constant of said integrating circuit to a high value, and means for detecting the duration of an iNtersection of a line scan with a feature and for activating the means for increasing the integrating circuit time constant for the duration of each such intersection.
Claim 3
Dependent Claim
46 words
An image analysis system according to claim 1 further comprising means for delaying the unmodified video signal by a time interval equal to the rise time of the signal path containing the so-called integrating circuit and means for supplying the delayed video signal to the detector.
Claim 4
Dependent Claim
58 words
An image analysis system according to claim 2 further comprising a subsidiary threshold detector having a preset threshold for detecting the amplitude excursions of the video signal which exceed the preset threshold to generate a binary output signal one of the two values of which are operative to activate the means for increasing the ingetrating circuit time constant.
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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) | 1977-05-27 | 1977-11-26 | 1978-05-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-05-27 | 1981-11-26 | 1982-05-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-05-27 | 1985-11-26 | 1986-05-28 | $7700.00 | Window Closed / Lapsed |