Image reading apparatus

Claim 1

An image reading apparatus comprising: (a) image reading means for reading an image in a reading area including an inside and an outside of an original document area to obtain image data; (b) a memory for storing the image data obtained by the image reading means; (c) edge detecting means for detecting a plurality of edges in the original document area according to the image data obtained by the image reading means, wherein said detecting means detects a first difference in values on coordinates between two adjacent edges of the plurality of edges, determines an inclination of the two adjacent edges based on the first difference, judges whether the inclination has an inclination angle of less than 45°, and then selects edges having the inclination angle of less than 45° by applying a first template matching to the judgment result, and wherein said detecting means detects a second difference in values on coordinates between two adjacent first differences, determines a singular edge point which does not designate the edge of the original document by applying a second template matching different from the first template matching, and then eliminates the singular edge point from the selected edges having the inclination angle of less than 45°; (d) calculating means for calculating an inclination angle of an original document based on the selected edges; and (e) correcting means for correcting the inclination angle of the original document based on the inclination angle calculated by the calculating means with respect to at least the image data in the original document area among the image data stored in the memory.