Patent ID: 8467111

Claim:
An image reading apparatus comprising: an image reading unit that includes a light source and a light receiving unit receiving light, and that reads an image of a document sheet having a plurality of image reading conditions set in advance, the light being emitted from the light source and reflected on the document sheet; a first light quantity information acquiring unit that acquires, as a plurality of pieces of first light quantity information a plurality of pieces of information on a quantity of light emitted from the light source to a first white reference plate and received by the light receiving unit for each one of the plurality of reading conditions respectively; a second light quantity information acquiring unit that acquires, as second light quantity information for at least one fewer reading condition than a total number of the plurality of reading conditions, information on a quantity of light emitted from the light source to a second white reference plate and received by the light receiving unit; a third light quantity information acquiring unit that acquires the second light quantity information for a reading condition other than the at least one fewer reading condition, by using the plurality of pieces of first light quantity information acquired by the first light quantity information acquiring unit; and a controller that controls reading the image of the document sheet differently for each one of the plurality of reading conditions respectively, wherein the first light quantity information acquiring unit exposes the first white reference plate for each one of the plurality of reading conditions respectively.