| 摘要 |
PURPOSE:To satisfactorily hold a color reproducibility, and to prevent a picture deterioration by mutually making different a striped screen angle against the halftone image of each color component except a black component, and setting a striped screen pitch so as to be almost equal. CONSTITUTION:Screen writing control means 3a-3d shift the writing timing of the striped screen at least for the color component halftone image except the black component halftone image formed by single color image forming units 1a-1d only in a constant amount normalized corresponding to each color component by each scanning line, and mutually make different the striped screen angle of each color component. On the other hand, screen frequency adjusting means 4a-4d adjust the striped screen spatial frequency in the main scanning direction for each color component, and sets the striped screen pitch for each color component halftone image so as to be almost equal. Thus, the color reproducibility can be satisfactorily held, and the picture deterioration such as the deterioration of the gradation can be validly prevented. |
