The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 19, 1994
Filed:
Sep. 20, 1991
Alpha Image Limited, , GB;
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.