| 摘要 |
In a printing apparatus that enables at least three different types of dots to be created in different ink weights by at least two different inks having an identical hue but different densities, the halftone processing is carried out in an appropriate sequence and according to an appropriate technique, which are determined by taking into account both the dispersibility of dots and the processing speed. The method of the present invention determines the on-off state of six different types of dots, which have different ink densities and ink weights, in the sequence of the large deep dot, the medium deep dot, the small deep dot, the large light dot, the medium light dot, and the small light dot. The dots created by an identical ink are subjected to the determination for the on-off state in a consecutive manner. A dither method that utilizes the recording ratio set for each type of dot according to the tone data is adopted in the determination for the on-off state of the dot. The method determines the on-off state of a target dot, based on a corrected recording ratio. The corrected recording ratio is obtained by adding the recording ratios of all the dots previously subjected to the determination for the on-off state to the recording ratio of the target dot. For example, the sum of the recording ratios of the large deep dot, the medium deep dot, and the small deep dot and the recording ratio of the large light dot is used in the determination for the on-off state of the large light dot. This arrangement of the present invention effectively prevents the different types of dots, especially the dots created by the identical ink, from being created in an identical pixel in an overlapping manner. One modified structure determines the on-off state of the small light dot by an error diffusion method. This improves the picture quality of the resulting printed image.
|
