Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1995-06-05
1998-05-05
Vu, Kim
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
358463, 358465, 348572, 341156, 341159, 341200, H04N 100
Patent
active
057483353
ABSTRACT:
An image reading apparatus such as a color copying apparatus has a plurality of sensing CCD chips for converting an image of an object into an electrical signal, each sensing CCD chip having a plurality of sensing elements. The apparatus also has a circuit for converting the electrical signal into digital data. A first adjusting circuit is provided for conducting either an operation for obtaining level matching of the electrical signal converted by the sensing chips, or an operation for controlling the gain of the electrical signal converted by the sensing chips. The apparatus further has a second adjusting circuit for effecting compensation for fluctuation of characteristics of the sensing elements of the sensing chips, by making use of the digital data converted by the converting circuit, the second adjusting circuit being adapted for effecting the compensation on the basis of electrical signals which are produced as a result of conversion by the sensing chips from two objects having different levels of density from each other, such as white and black levels. An analog-to-digital converter may also be provided to convert analog data into digital data. In that case, first adjusting means will adjust the analog data discretely, through a step smaller than the quantizing step used in the A/D conversion, and a second adjusting means may preferably further adjust the analog data in accordance with digital data obtained through the A/D conversion.
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Hasegawa Shizuo
Honma Toshio
Itagaki Hiroshi
Matsuoka Nobuo
Sasahara Kenji
Canon Kabushiki Kaisha
Vu Kim
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