Patent ID: 8077349

Claim:
An image processing apparatus comprising: an image data input unit that scans an original document in a main scanning direction and generates image data of the original document based on the scanned original document, the original document having a leading edge, a trailing edge, and a side edge disposed between the leading edge and the trailing edge; a density variation detection unit that detects density variation at the leading edge, the trailing edge, and the side edge of the original document in the image data generated by the image data input unit in a sub-scanning direction of the image data that is substantially perpendicular to the main scanning direction; and a position/size detection unit that detects a first position of a leading edge side end pixel at an outermost position of the side edge in a leading end portion of the image data that includes data scanned before the leading edge of the original document and a second position of a trailing edge side end pixel at an outermost position of the side edge in a trailing end portion of the image data that includes data scanned after the trailing edge of the original document based on the density variation detected by the density variation detection unit; and an image processing unit that calculates an inclination of the original document from the first position and the second position detected by the position/size detection unit and corrects the inclination.