Image reading apparatus, image reading method, and non-transitory computer readable medium

An image reading method comprising:

• reading an image from a recording medium via a first optical imaging system and a second optical imaging system, the first optical imaging system and the second optical imaging system being disposed such that respective reading regions partially overlap each other in a principal scanning direction on a reading surface;
• calculating a sum of a distance over which a first image captured by the first optical imaging system is displaced in the principal scanning direction with respect to a reference point and a distance over which a second image captured by the second optical imaging system is displaced in the principal scanning direction with respect to the reference point, the reference point being included in a region in which the reading regions overlap each other on the reading surface;
• calculating a first distance, over which the first image is displaced in the principal scanning direction, and a second distance, over which the second image is displaced in the principal scanning direction, by weighting the sum by a first reading angle, at which the first optical imaging system reads the reference point, and by a second reading angle at which the second optical imaging system reads the reference point;
• and
• correcting a position of the first image in the principal scanning direction using the first distance, and correcting a position of the second image in the principal scanning direction using the second distance,
• wherein calculating the first distance further comprises weighting the sum by a ratio of the first reading angle to a sum of the first reading angle and the second reading angle.

A non-transitory computer readable medium storing a program causing a computer to execute a process comprising:

• reading an image from a recording medium via a first optical imaging system and a second optical imaging system, the first optical imaging system and the second optical imaging system being disposed such that respective reading regions partially overlap each other in a principal scanning direction on a reading surface;
• calculating a sum of a distance over which a first image captured by the first optical imaging system is displaced in the principal scanning direction with respect to a reference point and a distance over which a second image captured by the second optical imaging system is displaced in the principal scanning direction with respect to the reference point, the reference point being included in a region in which the reading regions overlap each other on the reading surface;
• calculating a first distance, over which the first image is displaced in the principal scanning direction, and a second distance, over which the second image is displaced in the principal scanning direction, by weighting the sum by a first reading angle at which the first optical imaging system reads the reference point, and by a second reading angle at which the second optical imaging system reads the reference point;
• and
• correcting a position of the first image in the principal scanning direction using the first distance, and correcting a position of the second image in the principal scanning direction using the second distance,
• wherein calculating the first distance further comprises weighting the sum by a ratio of the first reading angle to a sum of the first reading angle and the second reading angle.