Image analysis – Histogram processing – For setting a threshold
Patent
1995-05-02
1997-12-16
Coles, Sr., Edward L.
Image analysis
Histogram processing
For setting a threshold
382270, 358464, 358465, G06K 938
Patent
active
056994540
ABSTRACT:
An image processing apparatus includes a detecting section for detecting a density value as a threshold value for suppressing an effect from a background from image data composed of plural picture element data obtained by digitizing each picture element of the image and a density converting section for outputting the image data after converting density values of the picture element data whose density values are below the threshold value into a predetermined value indicating white when the density value of the picture element data is below the threshold value. The detecting section computes a degree of separation indicating a ratio of a between-class dispersion to a within-class dispersion of two classes divided by the threshold value by sequentially varying the density value. Then, the density value corresponding to a gravitational center of a differential histogram showing the respective differences in degree of separation from a density Tm which maximizes the degree of separation to a highest density Te. The apparatus enables an effective threshold value to be set even with respect to the image data wherein a difference in density level between the background and the image is not significant, thereby enabling the removal of the background from such image data.
REFERENCES:
patent: 5138671 (1992-08-01), Yokoyama
patent: 5157740 (1992-10-01), Klein et al.
patent: 5351313 (1994-09-01), Bessho et al.
patent: 5400415 (1995-03-01), Kobayashi
Nakai Yoshiyuki
Taniguchi Keiji
Yamamoto Youichi
Brinich Stephen
Coles Sr. Edward L.
Conlin David G.
Michaelis Brian L.
Sharp Kabushiki Kaisha
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