Pattern outline tracking method and apparatus

[54] PATTERN OUTLINE TRACKING METHOD AND APPARATUS

[75] Inventors: Kazuhiko Saka, Joyo; Atsushi

Hisano, Nagaokakyo; Michitaka
Kato, Kyoto; Toshimichi Masaki,
Takatsuki; Nobuo Nakatsuka, Kyoto,
all of Japan

[73] Assignee: Omron Tateisi Electronics Co.,
Kyoto, Japan

[21] Appl. No.: 760,607

[22] Filed: Jul. 30, 1985

[30] Foreign Application Priority Data

Jul. 31, 1984 [JP] Japan 59-162264

[51] Int. CI.4 G06K 9/30; G06K 9/46

[52] U.S. CI. 382/22; 382/25;

382/27; 382/60

[58] Field of Search 382/60, 22, 27, 50,

382/25, 8, 9

[56] References Cited

U.S. PATENT DOCUMENTS

3,643,215 2/1972 Ingham 382/37

3,737,854 6/1973 Klemt 382/50

4,091,394 5/1978 Kashioka et al 382/22

4,115,761 9/1978 Ueda 382/37

4,295,121 10/1981 Enser 382/9

4,435,835 3/1984 Sakow 382/48

4,468,704 8/1984 Stoffel 358/282

4,504,971 3/1985 Nadler 382/9

4,510,616 4/1985 Lougheed 382/25

4,520,505 5/1985 Yamamoto 382/54

4,555,798 11/1985 Broadbent 382/27

4,561,106 12/1985 Yoshida 382/25

4,566,128 1/1986 Araki 382/60

4,593,325 6/1986 Kannapell 382/50

4,624,013 11/1986 Urushibata 382/9

4,628,532 12/1986 Stone 382/25

OTHER PUBLICATIONS

"Digital Contour Following", IBM Technical Disclosure Bulletin, vol. 17, No. 12, May 1975, J. L. Crawford & G. W. Volkman, pp. 3691-3692.

Primary Examiner—Leo H. Boudreau
Assistant Examiner—A. Anne Skinner
Attorney, Agent, or Firm—Stevens, Davis, Miller &
Mosher

[57] ABSTRACT

A pattern outline tracking system provides the functions that include scanning an object to be recognized and providing a series of analog video signals, comparing a video signal level with the specific, variable threshold level and providing a binary signal consisting of a sequence of serial bits, holding the binary signal bits as the input image pattern in an image memory, deriving partial patterns sequentially from the serial binary signal bits, each of the partial patterns consisting of a matrix of vertical and horizontal lines each containing specific numbers of pixels, matching the partial patterns against the corresponding reference patterns containing the previously defined starting points to be tracked, holding the address in the image memory for the certain pixel within the partial pattern identified in the matching step as the possible point address for the tracking operation, and tracking the outline of the input image pattern on the image memory in accordance with the possible point address.

6 Claims, 8 Drawing Figures