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System for generating a display of graphic objects over a video camera picture

  • US 4,591,897 A
  • Filed: 03/08/1984
  • Issued: 05/27/1986
  • Est. Priority Date: 03/08/1984
  • Status: Expired due to Term
First Claim
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1. A video display system for displaying a graphic object over a camera picture comprising a camera picture source of a first video signal representing a camera picture, a display means having a display screen and operable to produce an image on said display screen in a raster scan of said display screen and in response to an applied video signal, a memory, means to store data in said memory representing a graphic object to be displayed over said camera picture by said display means, said data identifying each edge point on said graphic object where said raster scan crosses the edge of said object in the display thereof by said display means, said data including a variable for each of said edge points varying in accordance with the slope that the edge of said object at such edge point makes with the scan line of said raster scan, and display creation means responsive to said first video signal from said camera picture source and responsive to the data stored in said memory to generate a second video signal and apply said second video signal to said display means to cause said display means to display the object represented by said data over said camera picture, said display creation means causing said second video signal to undergo a transition between said first video signal and a third video signal representing said graphic object at each of said edge points with the width of the transition varying in accordance with the slope that the object edge makes with the raster scan line at such edge point, said display means generating said second video signal within said transitions by mixing changing amounts of said first video signal with changing amounts of said third video signal.

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