Reading device, image forming apparatus, correction value calculating method, and storage medium storing program code

A method of calculating a correction value using a position reference member including a reference pattern having a line extending along a first direction of the position reference member, the position reference member movable in a second direction orthogonal to the first direction, and a reader including a plurality of sensor chips arranged along one direction of the reader, the method comprising:

• detecting, using the reader, the reference pattern having the line extending along the first direction of the reference pattern member, the reference pattern corresponding to each of the plurality of sensor chips arranged along the one direction in the reader, and each of the sensor chips having a length defined by a plurality of pixels;
• determining coordinates of at least two sensor chips in the second direction, among the plurality of sensor chips, based on the detected reference pattern of the position reference member;
• and
• correcting a position of a reading target in the second direction based on the coordinates determined for the at least two sensor chips of the reader in the second direction.