Image analysis – Histogram processing – For setting a threshold
Patent
1990-04-11
1991-09-17
Boudreau, Leo H.
Image analysis
Histogram processing
For setting a threshold
382 16, 382 22, 382 62, 382 65, 235448, G06K 700, G06K 948, G06K 704
Patent
active
050502310
ABSTRACT:
A relief image scanner scans successive linear areas on an information-carrying medium such as a plastic card, illuminating each area from two different directions. The reflected light is converted to first gray-level data when the illumination is from one direction, and to second gray-level data when the illumination is from the other direction. The second gray-level data are subtracted from the first gray-level data; then the difference, and its additive inverse, are compared with a threshold to detect edges of relief patterns on the card, and pairs of edges are connected to create an accurate, distortion-free image of the relief. Additional facilities may be provided to extract edge skeletons before joining the edges, and to capture printed information by binarizing the gray-level data.
REFERENCES:
patent: 3774015 (1973-11-01), Lockard
patent: 4628195 (1986-12-01), Baus
patent: 4845770 (1989-07-01), Koshida
patent: 4878125 (1989-10-01), Katayama et al.
Kitagawa Tohru
Sakai Shunji
Sekiguchi Takehito
Watanabe Naohiro
Boudreau Leo H.
Fallon Steven P.
OKI Electric Industry Co., Ltd.
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