Image reading device, image forming apparatus, and image reading method

An image reading method performed by an image reading device

• the image reading device including
• a plurality of reading devices arranged in a main scanning direction perpendicular to a sub-scanning direction in which a reading target is transported, and
• a plurality of position reference members each including a reference pattern as a reference for correcting relative positions of a plurality of pixels in each of the plurality of reading devices or relative positions of the plurality of reading devices,
• the plurality of position reference members partially overlapping the plurality of reading devices, and being configured to move in the sub-scanning direction relative to the plurality of reading devices, and
• the plurality of position reference members including
• one or more first position reference members for correcting the relative positions of the plurality of reading devices, the number of the one or more first position reference numbers being less than the number of the plurality of reading devices by one, and
• a plurality of second position reference members for correcting the relative positions of the plurality of pixels in each of the plurality of reading devices, the number of the plurality of second position reference members being equal to the number of the plurality of reading devices, and
• the image reading method comprising:
• reading the plurality of position reference members with the plurality of reading devices to obtain a reading result;
• and
• calculating a correction value corresponding to a deviation of the relative positions of the plurality of pixels in each of the plurality of reading devices and a correction value corresponding to a deviation of the relative positions of the plurality of reading devices, while switching between the one or more first position reference members and the plurality of second position reference members.