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

• Current Assignee: Futec, Inc.
• Original Assignee: Futec, Inc.
• Inventors: Nishio, Masami
• Primary Examiner(s): Couso, Jose L.
• Application Number:
  US07/636,127
• Time in Patent Office: 1,016 Days
• Field of Search: 382/8, 382/22, 382/34, 382/48, 358/101, 358/106, 358/107
• US Class Current: 382/112
• CPC Class Codes: G06T 2207/30164 Workpiece; Machine component
• CPC Class Codes: G06T 7/001 using an image reference approach
• CPC Class Codes: G06V 10/751 Comparing pixel values or logical combinations thereof, or feature values having positional relevance, e.g. template matching

Abstract

A method for matching patterns includes the steps of optically scanning a master image and a to-be-recognized image and outputting master image data and to-be-recognized image data, extracting master outline data representing an outline of the master image from the master image data, extracting to-be-recognized outline data representing an outline of a to-be-recognized image from the to-be-recognized image data, performing an enlargement process for the to-be-recognized outline data to enlarge the to-be-recognized outline, thereby forming to-be-recognized outline data, and collating the master outline data with the to-be-recognized outline data, and if a portion of the master outline projects from the to-be-recognized outline, determining that the to-be-recognized image has a short-defect indicating an omission of the image

Claims

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.

2. A method according to claim 1, wherein said collating step includes a step of checking whether the defect information is true defect information.

3. A method according to claim 1, wherein said collating step comprises a step of fetching the first outline data and the third outline data in synchronism with each other, and a step of comparing the first and third data with each other.

4. A method of matching patterns, which is used for detecting a defect in a printed pattern on printed matter, comprising:

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

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

a fourth step of subjecting to the first and second outline data an enlargement process to enlarge the outline of the reference printed pattern and the outline of the to-be-recognized printed pattern and to form third and fourth outline data corresponding respectively to an enlarged outline of the reference printed pattern and an enlarged outline of the to-be-recognized printed pattern;

a fifth step of collating the first outline data with the fourth outline data, to output first defect information indicating that the to-be-recognized printed pattern contains a short-defect indicating an omission of a part of the to-be-recognized printed pattern when the outline of the reference printed pattern mismatches with the outline of the enlarged to-be-recognized printed pattern; and

a sixth step of collating the third outline data with the second outline data, to output second defect information indicating that the to-be-recognized printed pattern contains a splashing defect indicating an inclusion of a printed pattern regardless of the to-be-recognized printed pattern when the outline of the enlarged reference printed pattern mismatches with the outline of the to-be-recognized printed pattern.

5. A method according to claim 4, wherein said fifth and sixth steps respectively include steps of checking whether the first and second defect information are true defect information.

6. A method according to claim 4, wherein said fifth step comprises a step of fetching the first outline data and the fourth outline data in synchronism with each other and comparing them with each other, and said sixth step comprises a step of fetching the third outline data and the second outline data in synchronism with each other and comparing them with each other.

7. An apparatus for matching patterns, which is used for detecting a defect in a printed pattern on printed matter, comprising:

pattern data output means for optically scanning a reference printed pattern having an outline and a to-be-recognized printed pattern having an outline and outputting first and second pattern data;

outline data output means for extracting and outputting first outline data representing the outline of the reference printed pattern from the first pattern data, and for extracting and outputting second outline data representing the outline of the to-be-recognized printed pattern from the second pattern data;

enlarged outline data output means for subjecting the second outline data to an enlargement process to enlarge the outline of the to-be-recognized printed pattern, and outputting third outline data representing an enlarged outline of the to-be-recognized printed pattern; and

collating means for 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.

8. An apparatus according to claim 7, wherein said collating means includes a determining circuit for checking whether the defect information is true defect information.

9. An apparatus according to claim 7, wherein said collating means comprises a pattern matching circuit for fetching the first outline data and the third outline data in synchronism with each other and comparing them with each other.

10. An apparatus according to claim 7, wherein said outline data output means has memory means for storing the first outline data, and said collating means comprises a pattern matching circuit for comparing the first outline data read out from said memory means with the third outline data input from said enlarged outline data output means in synchronism with the read operation of the first outline data.

11. An apparatus according to claim 7, wherein said image data output means comprises image sensor means for optically scanning a plurality of printed materials each having a predetermined printed pattern corresponding to the to-be-recognized printed pattern.

12. An apparatus for matching patterns, which is used for detecting a defect in a printed pattern on printed matter, comprising:

pattern data output means for optically scanning a reference pattern having an outline and a to-be-recognized pattern having an outline and outputting first and second pattern data corresponding respectively to the reference pattern and the to-be-recognized pattern;

outline data output means for extracting and outputting first outline data representing the outline of the reference pattern from the first pattern data, and for extracting and outputting second outline data representing the outline of the to-be-recognized pattern from the second pattern data;

enlargement means for subjecting the first and second outline data to an enlargement process to enlarge the outlines of the reference and to-be-recognized patterns and output third and fourth outline data corresponding respectively to enlarged outlines of the reference and to-be-recognized patterns;

first collating means for collating the first outline data with the fourth outline data, and outputting first defect information indicating that the to-be-recognized printed pattern contains a short-defect indicating an omission of a part of the to-be-recognized printed pattern when the outline of the reference printed pattern mismatches with the outline of the enlarged to-be-recognized printed pattern; and

second collating means for collating the third outline data with the second outline data, and outputting second defect information indicating that the to-be-recognized printed pattern contains a slashing defect indicating an inclusion of a printed pattern regardless of the to-be-recognized printed pattern when the outline of the enlarged reference printed pattern mismatches with the outline of the to-be-recognized printed pattern.

13. An apparatus according to claim 12, wherein said first and second collating means respectively include first and second determining circuits for checking whether the first and second defect information are true defect information.

14. An apparatus according to claim 12, wherein said first collating means comprises a first pattern matching circuit for fetching the first outline data and the fourth outline data in synchronism with each other and comparing them with each other, and said second collating means comprises a second pattern matching circuit for fetching the third outline data and the second outline data in synchronism with each other and comparing them with each other.

15. A method of matching patterns, which is used for detecting a defect in a pointed pattern on printed matter, comprising:

a first pattern matching process including a step of fetching master pattern data corresponding to a master pattern having an outline into outline extracting means, to extract master pattern outline data corresponding to the outline of the master pattern from the master pattern data, a step of storing the master pattern outline data obtained by the extraction into memory means, a step of extracting to-be-recognized pattern outline data corresponding to an outline of a to-be-recognized printed pattern from to-be-recognized printed pattern data corresponding thereto by said outline extracting means, a step of subjecting the extracted to-be-recognized pattern outline data to a pattern enlargement process to form enlarged to-be-recognized pattern outline data corresponding to an enlarged to-be-recognized pattern, and a step of collating the enlarged to-be-recognized outline data with the master pattern outline data; and

a second pattern matching process including a step of subjecting the master pattern outline data to the pattern enlargement process to form an enlarged master pattern outline data, a step of storing the master pattern outline data into second memory means, a step of extracting the to-be-recognized pattern outline data by said outline extracting means, and collating the to-be-recognized pattern outline data with the enlarged master pattern outline data,

wherein said first and second pattern matching processes are performed parallel to each other.

16. An apparatus for matching pattern, which is used for detecting a defect in a printed pattern or printed matter, comprising:

outline extracting means for independently fetching master pattern data and to-be-recognized pattern data corresponding respectively to a master pattern and a to-be-recognized pattern and extracting master pattern outline data and to-be-recognized pattern outline data corresponding to outlines of the master and to-be-recognized patterns, respectively, from master pattern data and to-be-recognized pattern data;

pattern enlargement processing means, connected to said outline extracting means, for subjecting the extracted master and to-be-recognized pattern outline data to an enlargement process to form enlarged master and to-be-recognized pattern outline data;

first memory means, for storing the master pattern outline data;

first pattern matching means, connected to output terminals of said first memory means and said pattern enlargement processing means, for collating the master pattern outline data with the enlarged to-be-recognized pattern outline data;

second memory means, connected to the output terminal of said pattern enlargement processing means, for storing the enlarged master pattern outline data; and

second pattern matching means, connected to output terminals of said second memory means and said outline extracting means, for collating the enlarged master patter outline data with the to-be-recognized pattern outline data obtained by said outline extracting means.