9. A method according to claim 6, wherein address words of the third sequence 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.
10. A method according to claim 9, wherein the address words of the third sequence that define locations of the input scene having the first-mentioned selected spatial relationship with said predetermined location are modified by adding each of them to the first-mentioned offset word and the address words of the third sequence that define locations to the input scene having the second selected spatial relationship with said predetermined location are modified by subtracting each of them from the second offset word.