US Patent 7525693 Image reading apparatus and image reading method

There is provided a technique that, when shading compensation is performed in an image reading apparatus, is less prone to be influenced by a smudge or the like adhered to a document glass or a white reference plate to be read by an optical reading system, and hence is able to contribute to an improvement in the quality of read images. Provision is made for an optical system control part that operates to make an optical reading system read a white reference plate through a document glass in a first predetermined range in a direction of movement of the optical reading system when an image of a document placed on the document glass is read by driving the optical reading system to move in a predetermined direction at the time of shading compensation, and make the optical reading system read the white reference plate through the document glass by the optical reading system in a second predetermined range in the direction of movement of the optical reading system when an image of a moving document is read by the optical reading system that is stopped at a predetermined position; and a compensation part that performs shading compensation based on image information obtained by the optical reading system reading the white reference plate in the predetermined ranges.