US4947255A
Expired / Lapsed
US
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Video luminance self keyer
Assignee: Grass Valley USA LLC
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Filing: 1988-09-19
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Granted: 1990-08-07
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Expires: 2008-09-19
Abstract
Abstract An improved luminance video self keyer extracts a key signal from an unshaped input video signal as a function of a low and a high clip level. The input video signal is subsequently "shaped" as a function of the key signal and the low clip level. The result is a shaped video signal and an associated key signal that are combined with a secondary video signal without resorting to double multiplication of the input video signal by its associated key signal to produce a desired combination of the two video signals.
Inventors
- 👤 Richard A. Jackson
- 👤 Richard S. Bannister
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 19:47
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/222; H04N5/262; H04N5/272; H04N5/275
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
56 words
A keyer comprising: means for extracting a key signal from an input video signal as a function of a clip level that defines one extreme of a transition region for the key signal; and means for shaping the input video signal using the key signal and the clip level to produce a shaped input video signal.
Claim 2
Dependent Claim
56 words
A keyer comprising: means for extracting a key signal from an input video signal as a function of a clip level that defines one extreme of a transition region for the key signal; and means for shaping the input video signal using the key signal and the clip level to produce a shaped input video signal.
Claim 3
Dependent Claim
37 words
A keyer as recited in claim 1 further comprising means for combining the shaped input video signal with a secondary input video signal that is a function of the key signal to produce an output video signal.
Claim 4
Dependent Claim
15 words
A keyer as recited in claim 1 further comprising means for inverting the key signal.
Claim 5
Dependent Claim
46 words
A keyer as recited in claim 1 wherein the shaping means comprises: means for multiplying the clip level with the key signal to produce a shape signal; and means for combining the shape signal with the input video signal to produce the shaped input video signal.
Claim 6
Dependent Claim
46 words
A keyer as recited in claim 4 wherein the combining means comprises: means for subtracting the shape signal from the input video signal; and means for limiting the video signal from the subtracting means to allowable video signal limits to produce the shaped input video signal.
Claim 7
Dependent Claim
58 words
A keyer as recited in claim 3 wherein the inverting means comprises: means for inverting the input video signal prior to input to the extracting means in response to an invert signal; and means for mixing the input video signal with the clip level as a function of the invert signal prior to input to the shaping means.
Claim 8
Dependent Claim
22 words
A keyer as recited in claim 6 further comprising means for inverting the clip level prior to input to the shaping means.
Claim 9
Dependent Claim
73 words
A keyer as recited in claim 1 wherein the extracting means comprises: means for subtracting the clip level from the input video signal; means for multiplying the output of the subtracting means by a gain signal that defines the opposite extreme of the transition region with respect to the clip level; and means for limiting the output of the multiplying means to a range between zero and one to produce the key signal.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-08-06 | 1994-02-05 | 1994-08-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-08-06 | 1998-02-05 | 1998-08-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-08-06 | 2002-02-05 | 2002-08-07 | $7700.00 | Window Closed / Lapsed |