Image processing apparatus, image processing method, and inkjet printing apparatus

Patent metadata

Field	Value
Publication number	US-11052671-B2
Application number	US-201816214880-A
Country	US
Kind code	B2
Filing date	Dec 10, 2018
Priority date	Dec 15, 2017
Publication date	Jul 6, 2021
Grant date	Jul 6, 2021

Abstract

For a multi-pass printing, an image of a unit area is printed by M printing scans of M print regions of first and second nozzle arrays. Each of N pieces of column data is printed by a different printing scan. Ejection data for the first nozzle array is generated using a first mask pattern and ejection data for the second nozzle array is generated using a second mask pattern different from the first mask pattern, for each of the N pieces of column data. On that basis, the first mask pattern and the second mask pattern have a complementary relationship in each of the M print regions. Further, in each of the first mask pattern and the second mask pattern, a combination of print regions, of the M print regions, for printing dots at the same position on the print medium has a mutually complementary relationship.

First claim

What is claimed is:

1. An image processing apparatus generating ejection data for printing an image in a unit area of the print medium by repeating a printing scan and a conveyance operation alternately,
the printing scan being an operation of using a first nozzle array and a second nozzle array, each having a predetermined number of nozzles arrayed in a predetermined direction, the first nozzle array and the second nozzle array being arrayed in a direction intersecting the predetermined direction with nozzles of the first nozzle array corresponding in position in the predetermined direction with nozzles of the second nozzle array, and each nozzle being configured to eject the same kind of ink, and scanning the first nozzle array and the second nozzle array in a first scanning direction and a second scanning direction opposite to the first direction intersecting the predetermined direction while causing each nozzle to eject the ink toward the print medium,
the conveyance operation being an operation of conveying the print medium by a distance corresponding to each of M print regions obtained by dividing a predetermined number of nozzles of a nozzle array into M regions in the predetermined direction, M being an integer of four or more, in a conveying direction intersecting the direction of the printing scan,
the image in the unit area of the print medium being printed by M printing scans, and
the image processing apparatus comprising:
a column data generation unit configured to generate N pieces of column data that are binary dot data based on multi-level image data, N being an integer between four and M inclusive, such that some of the N pieces of column data indicates dot printing on the same pixel in a predetermined area of the print medium; and
an ejection data generation unit that generates ejection data for the first nozzle array using a first mask pattern that defines, in advance, print-permitted pixels at which dot-printing is permitted and print-not-permitted pixels at which dot-printing is not permitted with respect to the M print regions of the first nozzle array and the N pieces of column data, and generates ejection data for the second nozzle array using a second mask pattern, different from the first mask pattern, that defines, in advance, print-permitted pixels at which dot-printing is permitted and print-not-permitted pixels at which dot-printing is not permitted with respect to the M print regions of the second nozzle array and the N pieces of column data, so as to generate the ejection data for the first nozzle array and the ejection data for the second nozzle array, using different pieces of the column data of the N pieces of column data for respective different printing scans for the predetermined area of the print medium, and using the same pieces of the column data for the same printing scan,
wherein (i) a first part of the first mask pattern corresponding to at least one region of the M print regions of the first nozzle array used for one or more predetermined print scans in a first direction of the scanning direction for a first region and a first part of the second mask pattern corresponding to the at least one region of the M print regions of the first nozzle array used for the one or more predetermined print scans in the first direction for the first region have a complementary relationship,
(ii) a second part of the first mask pattern corresponding to another at least one region of the M print regions of the first nozzle array used for another predetermined print scan in the first direction for the first region and the first part of the first mask pattern have a complementary relationship, and
(iii) a second part of the second mask pattern corresponding to at least one region of the M print regions of the second nozzle array used in the one or more predetermined print scans in the first direction for the first region and the first part of the second mask pattern have a complementary relationship, and
wherein the ejection data generation unit generates the ejection data for the first nozzle array and the second nozzle array for the one or more predetermined print scans and the other scan in the first direction for the first region using the pieces of column data of the N pieces of column data which indicate dot forming on at least one same position.

2. The image processing apparatus according to claim 1 , wherein the column data generation unit determines dot-printing or dot-not-printing for each pixel, such that dots are printed with one on top of the other at the same pixel position on the print medium, regardless of tone level of the image data.

3. The image processing apparatus according to claim 1 , wherein the column data generation unit determines dot-printing or dot-not-printing for each pixel such that an area where dots are printed with one on top of the other at the same pixel position on the print medium and an area where dots are separately printed at different pixel positions on the print medium appear, regardless of tone level of the image data.

4. The image processing apparatus according to claim 1 , wherein in the first mask pattern and the second mask pattern, each of the M print regions has a print permission rate of 50%.

5. The image processing apparatus according to claim 1 , wherein each of the M and the N is four.

6. The image processing apparatus according to claim 1 , wherein the M is eight, and the N is four.

7. The image processing apparatus according to claim 1 , further comprising a printing unit that prints an image on the print medium using the first nozzle array and the second nozzle array according to the ejection data generated by the ejection data generation unit.

8. The image processing apparatus according to claim 1 , wherein the first nozzle array and the second nozzle array can print the same pixel areas on the print medium by one printing scan.

9. The image processing apparatus according to claim 1 , wherein binary dot data corresponding to a group of multiple pixels having a width of one pixel in the scanning direction and arranged continuously in the conveying direction is defined as one piece of column data.

10. An image processing method of generating ejection data for printing an image in a unit area of the print medium by repeating a printing scan and a conveyance operation alternately,
the printing scan being an operation of using a first nozzle array and a second nozzle array, each having a predetermined number of nozzles arrayed in a predetermined direction, the first nozzle array and the second nozzle array being arrayed in a direction intersecting the predetermined direction with nozzles of the first nozzle array corresponding in position in the predetermined direction with nozzles of the second nozzle array, and each nozzle being configured to eject the same kind of ink, and scanning the first nozzle array and the second nozzle array in a first scanning direction and a second scanning direction opposite the first direction intersecting the predetermined direction while causing each nozzle to eject the ink toward the print medium,
the conveyance operation being an operation of conveying the print medium by a distance corresponding to each of M print regions obtained by dividing a predetermined number of nozzles of a nozzle array into M regions in the predetermined direction, M being an integer of four or more, in a conveying direction intersecting the direction of the printing scan,
the image in the unit area of the print medium being printed by M printing scans, and
the image processing method comprising:
a column data generation step of generating N pieces of column data that are binary dot data based on multi-level image data, N being an int

Assignees

• Canon Kk

Inventors

• Kawafuji Hiroshi

Classifications

• G06K15/107

  Mask selection · CPC title

• B41J2/52

  Arrangement for printing a discrete number of tones, not covered by group B41J2/205, e.g. applicable to two or more kinds of printing or marking process (B41J2/525 takes precedence) · CPC title

• B41J2/2132 Primary

  Print quality control characterised by dot disposition, e.g. for reducing white stripes or banding (methods for local corrections by dot omission, image edge enhancement, or multi-pass mask selection G06K15/102; colour conversion H04N1/40) · CPC title

• G06K15/102

  using ink jet print heads · CPC title

• H04N1/4055

  producing a clustered dots or a size modulated halftone pattern · CPC title