Patent ID: 8482818

Claim:
An image reading apparatus comprising: a original platen on which an original document is placed; a light source configured to emit light toward the original document on said original platen; a sensor configured to read an image of the original document on said original platen; a reading unit configured to execute (i) a Light-on reading processing for turning on said light source and causing said sensor to read the original document on said original platen at a first resolution, and (ii) a Light-off reading processing for turning off said light source and causing said sensor to read the original document on said original platen at a second resolution; an image processing unit configured to remove an influence of external light included at a reading position outside the original document in a Light-on mode image read by the Light-on reading processing, in accordance with an influence of external light included at a reading position outside the original document in a Light-off mode image read by the Light-off reading processing; and a specifying unit configured to specify a boundary between an inside and an outside of the original document on said original platen based on a modified Light-on mode image in which said image processing unit has removed the influence of external light.