Image analysis – Histogram processing – For setting a threshold
Patent
1991-10-29
1994-09-13
Boudreau, Leo H.
Image analysis
Histogram processing
For setting a threshold
382 14, 382 25, 395912, G06K 900
Patent
active
053475917
ABSTRACT:
A printed board, on which a wiring pattern and a through hole to be inspected are provided, is scanned pixel by pixel and is read optically. The data obtained by scanning is converted into an electric signal to obtain image data. On the basis of the image data thus obtained, a pattern image representing the wiring pattern an a hole image representing the through hole are obtained. A center and a radius of the hole image are obtained from the image data. Then, a plurality of ring-shaped masks are obtained by magnifying the hole image at a plurality of magnifications. The size of the pattern image is normalized by the size of the hole image, and the, respective areas of overlapped regions between a plurality of the ringshaped masks and the pattern image are detected. Since these areas are obtained with an isotropic method, they do not depend on the directions of a line entering a land. By simulation, correspondence between the area of the overlapped regions and a relative positional relation between the wiring pattern and the through hole is obtained in advance. On the basis of this known correspondence, a relative positional relation between the wiring pattern and the through hole is evaluated by utilizing a neural network that has been taught such known correspondence.
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Hoki Tetsuo
Onishi Hiroyuki
Boudreau Leo H.
Dainippon Screen Mfg. Co,. Ltd.
Johns Andrew W.
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