Combining digital video key signals
First Claim
1. Video signal processing apparatus having means for manipulating digital video signals and digital key signals, including means for combining said digital key signals to form a composite digital key signal, comprising:
- selection means;
first switchable inverting means;
second switchable inverting means;
third switchable inverting means;
means for supplying a first digital key signal to said first selection means via said first switchable inverting means;
means for supplying a second digital key signal to said first selection means via said second switchable inverting means;
comparison means;
means for supplying said first digital key signal via said first switchable inverting means to said comparison means;
means for supplying said second digital key signal via said second switchable inverting means to said comparison means to produce a selection signal;
said selection means operating in response to said selection signal to produce a composite digital key signal, said composite digital signal being supplied to said third switchable inverting means to produce an output signal.
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Accused Products
Abstract
A mixer for combining digital video signals allows four real-time signals to be combined. At each layer, a digital key signal may be generated from the input video signal using chroma or luminance keying. In addition, the video signal may be combined with drop shadows, a border and a fill to produce first-stage composite video and composite key signals. A composite key signal is produced by supplying two key signals to a comparator and a selector via respective switchable invertors. The comparator produces a selection signal which is supplied to the selector via a switchable invertor. The selector switches an input signal to produce an output signal which is supplied to an output port via a switchable converter.
34 Citations
8 Claims
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1. Video signal processing apparatus having means for manipulating digital video signals and digital key signals, including means for combining said digital key signals to form a composite digital key signal, comprising:
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selection means; first switchable inverting means; second switchable inverting means; third switchable inverting means; means for supplying a first digital key signal to said first selection means via said first switchable inverting means; means for supplying a second digital key signal to said first selection means via said second switchable inverting means; comparison means; means for supplying said first digital key signal via said first switchable inverting means to said comparison means; means for supplying said second digital key signal via said second switchable inverting means to said comparison means to produce a selection signal; said selection means operating in response to said selection signal to produce a composite digital key signal, said composite digital signal being supplied to said third switchable inverting means to produce an output signal. - View Dependent Claims (2, 3, 4, 6)
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5. A method of processing digital video key signals, comprising the steps of:
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supplying a first digital key signal to a selection means via a first switchable inverting means, supplying a second digital key signal to said selection means via a second switchable inverting means, supplying said first digital key signal to a comparison means via said first switchable inverting means, supplying said second digital key signal to said comparison means via said second switchable inverting means, operating said selection means in response to an output from said comparison means and conveying an output digital signal from said selection means to an output port via a third switchable inverting means. - View Dependent Claims (7, 8)
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Specification