Patent ID: 11936835
Assignee: CANON KABUSHIKI KAISHA
Field: Audio-visual technology (Electrical engineering)
Classification: CPC H  B | IPC B  H

Claim 14:
15. An image printing method for a printing apparatus with a printing unit configured to print an image with a plurality of chromatic inks and an achromatic ink, wherein the printing apparatus includes a first nozzle array including a plurality of nozzles for discharging first chromatic ink arranged in a predetermined direction, a second nozzle array including a plurality of nozzles for discharging second chromatic ink arranged in the predetermined direction, a third nozzle array including a plurality of nozzles for discharging third chromatic ink arranged in the predetermined direction, and a fourth nozzle array including a plurality of nozzles for discharging achromatic ink arranged in the predetermined direction, prints an image in a first area on a printing medium with use of a first nozzle group including at least one nozzle in the first nozzle array, a second nozzle group including at least one nozzle in the second nozzle array, a third nozzle group including at least one nozzle in the third nozzle array, and a fourth nozzle group including at least one nozzle in the fourth nozzle array, and prints an image in a second area different in position in the predetermined direction from the first area on the printing medium with use of a fifth nozzle group in the first nozzle array, the fifth nozzle group not including nozzles included in the first nozzle group, a sixth nozzle group in the second nozzle array, the sixth nozzle group not including nozzles included in the second nozzle group, a seventh nozzle group in the third nozzle array, the seventh nozzle group not including nozzles included in the third nozzle group, and an eighth nozzle group in the fourth nozzle array, the eighth nozzle group not including nozzles included in the fourth nozzle group,
the image printing method comprising:
converting a first combination including a color signal corresponding to the first chromatic ink, a color signal corresponding to the second chromatic ink, a color signal corresponding to the third chromatic ink and a color signal corresponding to the achromatic ink, which are input to be printed in the first area, into a second combination including a color signal corresponding to the first chromatic ink, a color signal corresponding to the second chromatic ink, a color signal corresponding to the third chromatic ink, and a color signal corresponding to the achromatic ink, and
converting a third combination including a color signal corresponding to the first chromatic ink, a color signal corresponding to the second chromatic ink, a color signal corresponding to the third chromatic ink, and a color signal corresponding to the achromatic ink, which are input to be printed in the second area, into a fourth combination including a color signal corresponding to the first chromatic ink, a color signal corresponding to the second chromatic ink, a color signal corresponding to the third chromatic ink, and a color signal corresponding to the achromatic ink,
printing an image to the first area based on the converted color signal corresponding to the first chromatic ink included in the second combination, the converted color signal corresponding to the second chromatic ink included in the second combination, the converted color signal corresponding to the third chromatic ink included in the second combination and the converted color signal corresponding to the achromatic ink included in the second combination, and
printing an image to the second area based on the converted color signal corresponding to the first chromatic ink included in the fourth combination, the converted color signal corresponding to the second chromatic ink included in the fourth combination, the converted color signal corresponding to the third chromatic ink included in the fourth combination and the converted color signal corresponding to the achromatic ink included in the fourth combination,
wherein, in a case where values of the color signals in the first combination equal the respective values of the color signals in the third combination, and
(1) the value of the color signal corresponding to the achromatic ink is larger than 0,
(2) at least two of the values of the color signals corresponding to the first, second and third chromatic inks are larger than 0, and
(3) the value of the color signal corresponding to the achromatic ink is smaller than a sum of the values of the color signals corresponding to the at least two of the first, second and third chromatic inks,
the converting is performed such that the value of the color signal corresponding to the achromatic ink in the second combination equals the value of the color signal corresponding to the achromatic ink in the first combination, and the value of the color signal corresponding to the achromatic ink in the fourth combination equals the value of the color signal corresponding to the achromatic ink in the third combination,
so that a difference between a color of the image printed in the first area and a color of the image printed in the second area is reduced and a difference between a frequency of the image printed in the first area and a frequency of the image printed in the second area is reduced.