Patent ID: 8059135

Claim:
An image output apparatus, comprising: an image conversion unit that converts image data into an output image of intermediate gradation using a line screen for forming pixel points in stripes, the image data including a plurality of color elements; an element angle storing unit that stores the angle information of line segments of the image data for each color; a jaggy judging unit that judges whether or not jaggies will appear on the outline of the output image based on the angle information of the line segments stored in the element angle storing unit; and a screen angle setting unit that substantially changes the screen angle of the line screen if jaggies are judged to appear by the jaggy judging unit such that the angle difference between the screen angle of the line screen for each color element and the angle of the line segments for each color element is equal to or above a specified threshold value, wherein, if a first screen angle is set for a first color element and a second screen angle is set for a second color element in the case of outputting a color image, the screen angle setting unit changes the screen angle of the first color element from the first screen angle to the second screen angle when the jaggy judging unit judges that jaggies will appear in an image relating to the first color element while judging that jaggies will not appear in an image relating to the second color element.