| 摘要 |
PROBLEM TO BE SOLVED: To improve the resolution of a monochrome image by printing the image in such a state that the printing position of one of two monochrome images, one is formed by superimposing three-primary-color dots and the other is formed of black dots, is shifted in the widthwise and/or lengthwise directions of a print objective medium on the basis of the other monochrome image and the two images overlap each other partly. SOLUTION: Controllers 31 and 32 produce dot images from print image data PTD for monochrome printing. A position-shifted dot image producing device produces a dot image that is an assembly of primary-color dots with the printing position of the black dot image shifted based on position shifting data. A two-sort-print execute controller transfers dot images of black, yellow, magenta and cyan to color image printing controllers respectively. Image printers perform printing in such a way that primary-color dots to form a monochrome image are printed 1/2 dot ahead of the black dots, that form the other monochrome image, in the specified direction and 1/2 dot behind in another direction. |
