Digital video effects system employing a chroma-key tracking technique

Claim 1

A tracking system for producing special effects on a television picture, said television picture comprised of a first picture and a second picture inserted into said first picture, said first and second pictures being represented by first and second video signals respectively, said system comprising: means for producing a key signal representing a key frame to be positioned on said first picture; means for removing electrical noise signals from said key signal to produce a noise-removed key signal; means responsive to said noise-removed key signal for producing a position signal representing a position of a circumscribed frame of said key frame, said position signal including two horizontal position signal values and two vertical position signal values; means for producing a compressed second video signal representing a compressed second picture in response to said second video signal and said position signal; means responsive to said two horizontal position signal values and two vertical position signal values for producing a frame signal, said frame signal being applied to said removing means; and means responsive to said key signal for selectively combining said first video signal and said compressed second video signal, whereby said special effects are produced.