| 摘要 |
PROBLEM TO BE SOLVED: To suppress occurrence of a color irregularity or a moire pattern included in an image and to form the image with high quality independent of an image signal by providing a control means for changing a half tone processing to be adapted to each color an image forming means based on a periodical structure which is detected by means of a detecting means or the like. SOLUTION: Screen angles of respective C, M and Y colors of an original image and three kinds of screen patterns are compared for every color and one kind of screen pattern with a largest screen angle difference is selected. When the selected screen patterns are different for every color, the screen pattern is selected in priority order of M, C and Y. Thus, when the screen pattern is selected, communication is executed between a CPU 120 controlling a reader part 1000 and a CPU 118 of a printer part. The CPU 118 changes shift quantity of a phase at every main scanning line of a screen clock based on information of the selected screen pattern. |
