EP0070174A2
Expired / Lapsed
EP
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Digital chroma-key apparatus
Assignee: Sony Corp
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Filing: 1982-07-09
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Granted: —
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Expires: 2002-07-09
Abstract
Abstract In a digital chroma-key apparatus, a digital keying signal is generated by a keying signal processor 15 in response to specified chroma information of a first digital video signal (FG. VID) designating a foreground scene and the first digital video signal is switched into a second digital video signal (BG. VID) designating a background scene in accordance with level of the digital key signal. The digital key signal is adjusted in timing or compensated in level at portions of leading and trailing edges thereof so as to expand or compress the area of chroma-key.
Inventors
- 👤 Kaichi Yamamoto
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-03 14:52
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/64; H04N9/74; H04N9/75
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
69 words
A digital chroma-key apparatus comprising means for generating keying signal in response to specified chroma information of a first digital video signal, and means for mixing said first digital video signal with a second digital video signal in accordance with said digital keying signal characterised by means for adjusting said digital keying signal so as to expand or compress the leading and/or trailing edges of said digital keying signal.
Claim 2
Dependent Claim
69 words
A digital chroma-key apparatus comprising means for generating keying signal in response to specified chroma information of a first digital video signal, and means for mixing said first digital video signal with a second digital video signal in accordance with said digital keying signal characterised by means for adjusting said digital keying signal so as to expand or compress the leading and/or trailing edges of said digital keying signal.
Claim 3
Dependent Claim
51 words
A digital chroma-key apparatus according to claim 1, in which said adjusting means comprises means for detecting the leading and trailing edges of said digital key signal and level control means for amplifying or attenuating levels of the leading and trailing edges in response to commands of expansion or compression, respectively.
Claim 4
Dependent Claim
37 words
A digital chroma-key apparatus according to claim 2, in which said level control means comprises a memory which, in use, stores amplified or attenuated data to be read out therefrom at said leading edge and trailing edge.
Claim 5
Dependent Claim
45 words
A digital chroma-key apparatus according to claim 3, in which said memory is composed of a pair of random access memories which respectively store leading edge data and trailing edge data, said random access memories being operative in accordance with outputs of said detecting means.
Claim 6
Dependent Claim
61 words
A digital chroma-key apparatus according to claim 3 or 4, in which said detecting means comprises delay means for delaying said digital keying signal by a predetermined period and comparator for comparing said digital keying signal and said delayed digital keying signal from said delay means, the output of said comparator, in use, indicating said leading edge and said trailing edge.
Claim 7
Dependent Claim
72 words
A digital chroma-key apparatus according to claim 1, in which said adjusting means comprises means for detecting rate of change in said digital keying signal, means for generating coefficient in accordance with output of said detecting means and multiplier for multiplying said coefficient with said keying signal to produce an amplified or attenuated digital keying signal at said leading edge and trailing edge in response to commands of expansion or compression, respectively.
Claim 8
Dependent Claim
52 words
A digital chroma-key apparatus according to claim 6, in which said generating means comprises read only memory which, in use, stores a set of coefficients corresponding to said rate of change, said rate of change being supplied to said read only memory as address data to read out said corresponding coefficient therefrom.
Claim 9
Dependent Claim
75 words
A digital chroma-key apparatus according to claim 1, in which said adjusting means comprises means for forming first and second digital keying signal which respectively have delay amounts corresponding to an integral multiple of the sampling period,means for detecting leading and trailing edges of said digital keying signal and means for selecting one of said first and second digital keying signal in response to output of said detecting means and commands of expansion or compression.
References Cited (Backward Citations)
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