Patent ID: 8456678

Claim:
An image reading apparatus comprising: a document reading unit configured to read a document; a generation unit configured to generate gradation pattern data expressed with gradation for correcting a reading characteristic of the document reading unit; a display unit configured to display the gradation pattern data generated by the generation unit, wherein the display unit is electronic paper of which display contents are rewritable; a pattern reading unit configured to read the gradation pattern data displayed by the display unit; a display control unit configured to control displaying to the display unit, wherein the display control unit controls a voltage applied to the display unit to interpolate a difference of optical path lengths between a length when reading a document by the document reading unit and a length when reading the displayed gradation pattern data by the pattern reading unit; and a correction unit configured to correct the reading characteristic of the document reading unit, based on the gradation pattern data generated by the generation unit and the gradation pattern data read by the pattern reading unit.