Patent ID: 8514460

Claim:
An image reader having a main scanning direction and a sub-scanning direction perpendicular to the main scanning direction, comprising: a platen unit that includes a document area where a document is placed and a reference pattern area on an outer periphery of the document area, wherein the reference pattern area includes reference patterns drawn at predetermined intervals in the sub-scanning direction; a scanning unit that optically scans the document area and the reference pattern area while the scanning unit moves in the sub-scanning direction and forms an image on an imaging device via a lens, from which the imaging device generates an electrical signal; an image data generation unit that generates image data from the electrical signal generated by the imaging device and stores the image data in an image memory; a drive unit that reciprocates the scanning unit in the sub-scanning direction; an image processing unit that performs predetermined image processing on the image data stored in the image memory; a scaling factor calculation unit that calculates correction scaling factors for scaling a plurality of image areas in the sub-scanning direction, each image area being separated by the interval in the sub-scanning direction between adjacent ones of the reference patterns, so that the interval in the sub-scanning direction between adjacent ones of the reference patterns drawn in the reference pattern area is equal to the interval in the sub-scanning direction between adjacent ones of the reference patterns read by the image data; a scaling factor storage unit that stores the correction scaling factor for each image area; and a control unit that causes the image processing unit to scale the image data of the document in the sub-scanning direction for each image area according to the correction scaling factor stored in association with each respective image area in the scaling factor storage unit.