Image reading apparatus, control method, and control program

A control method of an image reading apparatus including a first unit fixed to the image reading apparatus, a second unit movable between a first position facing the first unit and a second position facing the first unit and more separated from the first unit than the first position, an image capturing device, provided in one of the first unit or the second unit for capturing a first image and a second image, a reference member provided in another one of the first unit or the second unit, and a driving device for moving the second unit between the first position and the second position, the method comprising:

• determining whether or not a foreign object appears in the first image;
• and
• determining whether the foreign object exists on a side of the image capturing device or on a side of the reference member, based on an absolute value of a difference between a gradation value in a region where the foreign object appears within the first image, and a gradation value in a region where the foreign object appears within the second image when the foreign object appears in the first image,
• wherein the first image is an image of the reference member captured when the second unit is at one of the first position or the second position, and the second image is an image of the reference member captured when the second unit is provided at another one of the first position or the second position.

A computer-readable, non-transitory medium storing a computer program, wherein the computer program causes an image reading apparatus including a first unit fixed to the image reading apparatus, a second unit movable between a first position facing the first unit and a second position facing the first unit and more separated from the first unit than the first position, an image capturing device, provided in one of the first unit or the second unit for capturing a first image and a second image, a reference member provided in the other of the first unit or the second unit, and a driving device for moving the second unit between the first position and the second position, to execute a process, the process comprising:

• determining whether or not a foreign object appears in the first image;
• and
• determining whether the foreign object exists on a side of the image capturing device or on a side of the reference member, based on an absolute value of a difference between a gradation value in a region where the foreign object appears within the first image, and a gradation value in a region where the foreign object appears within the second image when the foreign object appears in the first image,
• wherein the first image is an image of the reference member captured when the second unit is at one of the first position or the second position, and the second image is an image of the reference member captured when the second unit is provided at another one of the first position or the second position.