Patent attributes
In conventional image reading in a large-sized scanner using plural CIS sensors, overall linearity of an original is poor, and a shift occurs particularly at connection portions of the CIS sensors in the read image. To solve this, an image reading apparatus in which CISs are arranged zigzag, and an original is read while conveying the original by a conveyance roller in a direction different from an arrayed direction of the reading elements of the CIS sensors performs following correction. That is, a shift from an image position in a calibration sheet corresponding to a rotation angle of the conveyance roller for at each position of the CIS sensors is detected from image data obtained by reading the calibration sheet while conveying the calibration sheet by the conveyance roller. The shift is corrected.
