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Method of tracing contour and a system therefor

  • US 4,956,869 A
  • Filed: 02/10/1988
  • Issued: 09/11/1990
  • Est. Priority Date: 02/20/1987
  • Status: Expired due to Term
First Claim
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1. A method of tracing a contour to obtain contour coordinates by extracting segments of a contour of a figure from a sampled image, comprising the steps of:

  • scanning said figure along sequential scanning lines in a single scanning direction;

    detecting at least one image transition point for each sequential scanning line through said figure;

    extracting segments of the contour of the figure by comparing a detected relationship between the position of an image transition point of each scanning line and the position of an image transition point of the adjacent preceding scanning line to a plurality of basic patterns representing different positional relationship and selecting a basic pattern corresponding to each detected relationship along the contour of the figure;

    combining selected basic patterns into a basic pattern sequence on the basis of the positions of the detected image transition points; and

    converting said basic pattern sequence into a sequence of contour coordinates.

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