Patent ID: 7643179

Claim:
An image forming apparatus for recording images, comprising: an image processing unit to create image data for output including toner image data on four colors of yellow, cyan, magenta, and black such that toner images have line-shaped periodic structures; and an image forming unit to form the toner images using coloring materials of the four colors and superposing the toner images on a recording medium, wherein the line-shaped periodic structures of the toner images of the four colors are determined based on a combination of periodic structures having screen ruling and screen angles specified in table 1 below: TABLE 1 No. ruling angles a0x a0y a1x a1y 0 180.3 33.7 3 2 3 −2 1 180.3 146.3 −3 2 3 2 2 200.0 0.0 3 0 0 −3 3 200.0 90.0 0 3 3 0 where four values of a0x, a0y, a1x, and a1y correspond to x component, y component of a main vector and x component, y component of a sub-vector, respectively, and the four colors are designated to No. 0 to No. 3.