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Method of matching patterns and apparatus therefor

  • US 5,253,306 A
  • Filed: 12/31/1990
  • Issued: 10/12/1993
  • Est. Priority Date: 01/12/1990
  • Status: Expired due to Term
First Claim
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1. A method of matching patterns, which is used for detecting a defect in a printed pattern on printed matter, comprising the steps of:

  • a step of optically scanning a reference printed pattern having an outline and a to-be-recognized printed pattern having an outline to obtain first and second pattern data corresponding respectively to the reference printed pattern and the to-be-recognized printed pattern;

    a step of extracting master first outline data representing the outline of the reference printed pattern from the first pattern data;

    a step of extracting second outline data representing the outline of the to-be-recognized image from the second pattern data;

    a step of subjecting the second outline data to an enlargement process, for enlarging the outline of the to-be-recognized printed pattern, and for forming third outline data corresponding to an enlarged to-be-recognized outline; and

    a step of collating the first outline data with the third outline data, to output defect information indicating that the to-be-recognized printed pattern contains a defect when the outline of the reference printed pattern mismatches with the outline of the enlarged to-be-recognized printed pattern.

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