US 11,948,026 B2
Dither pattern forming method, image processing apparatus, and image processing method
Junichi Nakagawa, Tokyo (JP); Hirokazu Tanaka, Inagi (JP); Tsukasa Doi, Tokyo (JP); Mayuko Yamagata, Inagi (JP); and Satoshi Seki, Kawasaki (JP)
Assigned to CANON KABUSHIKI KAISHA, Tokyo (JP)
Filed by CANON KABUSHIKI KAISHA, Tokyo (JP)
Filed on Apr. 26, 2022, as Appl. No. 17/729,212.
Application 17/729,212 is a division of application No. 16/921,189, filed on Jul. 6, 2020, granted, now 11,334,778.
Claims priority of application No. 2019-131987 (JP), filed on Jul. 17, 2019.
Prior Publication US 2022/0253656 A1, Aug. 11, 2022
Int. Cl. G06K 15/02 (2006.01)
CPC G06K 15/1876 (2013.01) [G06K 15/1822 (2013.01); G06K 15/1878 (2013.01)] 20 Claims
OG exemplary drawing
 
1. An image printing apparatus comprising:
a storing unit configured to store a dither pattern having a quantization resolution in which a plurality of thresholds are set corresponding to pixel positions;
a quantization unit configured to compare a threshold in the dither pattern, the threshold corresponding to a processing target pixel in image data, with a multi-value gradation value of the processing target pixel to generate quantization data having the quantization resolution; and
a control unit configured to perform a predetermined control in which an image is printed by moving a printing unit and a printing medium relative to each other in a predetermined direction, based on the quantization data generated by the quantization unit, at a printing resolution higher than the quantization resolution in at least one of the predetermined direction and a direction crossing the predetermined direction,
wherein the dither pattern is formed in line with the following steps and then stored in the storing unit:
a generation step of generating an extended pattern corresponding to the printing resolution, a part of a plurality of subpixels included in the extended pattern being determined as dot-arrangeable-subpixels in which dots are allowed to be printed and the other part of the plurality of subpixels included in the extended pattern being determined as dot-not-arrangeable-subpixels in which dots are not allowed to be printed according to the predetermined control;
a selecting step of selecting a number of the dot-arrangeable-subpixels which number corresponds to a predetermined gradation value from among the plurality of the dot-arrangeable-subpixels in the extended pattern, so that an arrangement of the selected dot-arrangeable-subpixels has a predetermined dispersibility; and
a setting step of specifying, from a plurality of pixels in the dither pattern having the quantization resolution, pixels which correspond to the dot-arrangeable-subpixels selected in the extended pattern having the printing resolution, and setting thresholds to the specified pixels.