Color image reading apparatus having common circuitry for the color component signals

A color image reading apparatus comprising: reading means for reading a color image and dot sequentially outputting a plurality of analog color component signals; common amplifying means for sequentially amplifying the plurality of analog color component signals which are dot sequentially output from said reading means; common converting means for sequentially converting the plurality of analog color component signals, which are amplified by said common amplifying means, into a plurality of digital color component signals; separating means for separating the plurality of digital color component signals, which are converted by said common converting means, into digital color component signals of each color; and switching means for sequentially switching a gain of said common amplifying means in accordance with a color of the analog color signal to be amplified.

A color image reading apparatus comprising: reading means for reading a color image and dot sequentially outputting a plurality of analog color component signals; common setting means for sequentially setting a black level of the plurality of analog color component signals, which are dot sequentially output from said reading means, to a predetermined value; common correcting means for sequentially correcting a white level of the plurality of analog color signals whose black level was set to the predetermined value by said common setting means; common converting means for sequentially converting the plurality of analog color component signals, whose white level was corrected by said common correcting means, into a plurality of digital color component signals; and switching means for sequentially switching a correction ratio of said common correcting means in accordance with a color of the analog color component signal to be corrected.