Patent ID: 7016552

Claim:
An image processing device comprising: a binary image generating part that generates binary image data from inputted image data; a Hough transform part that executes Hough transform to the binary image data generated by the binary image generating part to generate Hough space data; a frequency calculating part that executes a calculation to each of frequencies of a coordinate that represents distance and angle in the Hough space data, tallies the attained calculation result by each angle, and generates first frequency calculation data based on the tallied result; and an angle detecting part that calculates a skew angle of the image data inputted by an input part based on the first frequency calculation data generated by the frequency calculating part, wherein the angle detecting part detects at least two maximum values or maximal values from the first frequency calculation data, and when an angle from a difference of the angles that give the maximum values or the maximal values is about π/2 (rad), the angle detecting part detects one of the angles as the skew angle.