EP0360518A1
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EP
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Improved video luminance self keyer
Assignee: Grass Valley Group Inc
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Filing: 1989-09-18
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Granted: —
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Expires: 2009-09-18
Abstract
Abstract A luminance video self keyer extracts (10), 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" (12,18) 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 (16) 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
EP
Data Source
google_patents
Last Synchronized
2026-11-09 15:23
CPC Classifications
H; H04; H04N; H04N5/00; H04N5/222; H04N5/262; H04N5/272; H04N5/275
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
60 words
A keyer comprising: means for extracting (10, 14) 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 (12, 18) the input video signal using the key signal and the clip level to produce a shaped input video signal.
Claim 2
Dependent Claim
60 words
A keyer comprising: means for extracting (10, 14) 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 (12, 18) 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 (16) the shaped input video signal with a secondary input video signal as a function of the key signal to produce an output video signal.
Claim 4
Dependent Claim
16 words
A keyer as recited in claim 1 further comprising means for inverting (40), the key signal.
Claim 5
Dependent Claim
48 words
A keyer as recited in claim 1 wherein the shaping means comprises: means for multiplying (18) the clip level with the key signal to produce a shape signal; and means for combining (12) 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
60 words
A keyer as recited in claim 3 wherein the inverting means comprises: means for inverting 40 the input video signal prior to input to the extracting means in response to an invert signal; and means for mixing 34 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
23 words
A keyer as recited in claim 6 further comprising means for inverting 32 the clip level prior to input to the shaping means.
Claim 9
Dependent Claim
76 words
A keyer as recited in claim 1 wherein the extracting means comprises: means for subtracting 42 the clip level from the input video signal; means for multiplying 44 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 46 the output of the multiplying means to a range between zero and one to produce the key signal.
References Cited (Backward Citations)
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