Patent Document ID: 4689682
Application ID: 06922589

Base Claim:
1. A method of deriving an output video signal from an input video signal that is representative of an input scene, comprising writing the input video signal into a frame buffer, generating a sequence of address words, comparing each address word with a reference word that defines a predetermined location of the input scene, modifying at least those address words that define locations of the input scene having a selected spatial relationship with said predetermined location by combining each of them with an offset word, whereby a modified sequence of address words is generated, and using the modified sequence of address words to read the video signal from the frame buffer.

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Claim 4:
4. A method according to claim 1, wherein address words that define locations of the input scene having a second selected spatial relationship with said predetermined location, the second selected spatial relationship and the first-mentioned selected spatial relationship being mutually exclusive, are modified by combining each of them with a second offset word.