Information reading apparatus

Details Information reading apparatus Information reading apparatus

1985-08-23

1988-11-08

Boudreau, Leo H.

Image analysis

Histogram processing

For setting a threshold

358163, 382 54, G06K 938

Patent

active

047838361

ABSTRACT:
In an information reading apparatus in which picture image data of manuscript read with a manuscript reader is converted into a digital signal including picture image data or shading correction reference density data of the manuscript, and the digital signal is converted into a logarithmic value. A memory device is used for storing the shading correction reference density data which has been converted into a logarithmic value and a subtractor is provided for subtracting data stored in the memory device at the time of no light input from picture image data and shading correction reference density data so as to effect a base level correction of the both data. A shading correction circuit is provided for effecting a shading correction based on the picture image data and the shading correction reference density data whose level have been corrected by the subtractor.

REFERENCES:
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patent: 4128830 (1978-12-01), Weythman
patent: 4355228 (1982-10-01), Sama et al.
patent: 4520395 (1985-05-01), Abe
patent: 4524388 (1985-06-01), Abe et al.
patent: 4554583 (1985-11-01), Saitoh et al.
patent: 4613269 (1986-09-01), Wilder et al.
Larson et al., Calculus with Analytic Geometry, page 320, 1980.

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