Image processing apparatus and image processing method

• US 10,127,481 B2
• Filed: 05/24/2016
• Issued: 11/13/2018
• Est. Priority Date: 05/27/2015
• Status: Active Grant

• Current Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Original Assignee: Canon Kabushiki Kaisha (Canon Inc.)
• Inventors: Kanda, Hidehiko, Kano, Yutaka, Komamiya, Eiji, Yazawa, Takeshi, Ohta, Ayako
• Primary Examiner(s): Luu, Matthew
• Assistant Examiner(s): Kemathe, Lily
• Application Number:
  US15/163,084
• Publication Number:
  US 20160350627A1
• Time in Patent Office: 903 Days
• CPC Class Codes: B41J 2/2132 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 Class Codes: G06K 15/107 Mask selection
• CPC Class Codes: G06K 15/1836 Rasterization
• CPC Class Codes: G06K 15/1843 Changing size or raster resolution

Abstract

With respect to an area quantized by using an area of part in a quantization pattern and also without using an area of the other part in the quantization pattern in quantized data, a mask pattern part corresponding to the area of the part among mask pattern parts constituted by dividing a mask pattern is applied.

Claims

1. An image processing apparatus for generating recording data used for each of a plurality of relative scanning operations of a recording head in an intersecting direction that intersects with a predetermined direction with respect to a unit area on a recording medium, the recording head including an ejection opening column having a plurality of ejection openings for ejecting ink arranged in the predetermined direction, the recording data specifying ejection or non-ejection of the ink to each of a plurality of pixel areas in the unit area on a recording medium corresponding to a plurality of pixels of the recording data, the image processing apparatus comprising:

one or more memories configured to store a dither pattern and a plurality of mask patterns corresponding to the plurality of relative scanning operations,

wherein each pixel area in the dither pattern has a respective threshold value for specifying ejection of ink to a corresponding pixel area on the recording medium,

wherein each pixel area in each of the plurality of mask patterns has respective information indicating permission or prohibition of ejection of ink to a corresponding pixel area on the recording medium,

wherein a number of pixel areas of the unit area corresponding to a conveyance amount between two sequential scanning operations is greater than a number of pixel areas in the dither pattern in the predetermined direction, the number of the pixel areas of the unit area corresponding to the conveyance amount being different from an integer multiple of the number of the pixel areas in the dither pattern in the predetermined direction, and

wherein the number of the pixel areas of the unit area corresponding to the conveyance amount is greater than a number of pixel areas in each of the plurality of mask patterns in the predetermined direction, the number of the pixel areas of the unit area corresponding to the conveyance amount being different from an integer multiple of the number of the pixel areas in the each of the plurality of mask patterns in the predetermined direction; and

one or more processors configured to execute the following steps of;

obtaining multi-value data corresponding to an image to be recorded in the unit area;

quantizing the multi-valued data by applying the dither pattern repeatedly in the predetermined direction to generate quantized data, wherein the quantizing the multi-valued data includes (i) generating a first area of the quantized data using a first part in the dither pattern without using a second part in the dither pattern, and (ii) generating a second area of the quantized data using the entire dither pattern, the second area of the quantized data being different from the first area of the quantized data; and

distributing the quantized data to the plurality of scanning operations by using the plurality of mask patterns to generate the recording data,

wherein each of the plurality of mask patterns is associated with the dither pattern, and

wherein the distributing the quantized data includes (i) applying, to the first area of the quantized data, a first part in each of the plurality of mask patterns without using a second part in the each of the plurality of mask patterns, and (ii) applying, to the second area of the quantized data, each of the plurality of mask patterns.

2. The image processing apparatus according to claim 1, further comprising:

a conveyance unit configured to convey the recording medium in the predetermined direction by a first distance during the plurality of scanning operations of the recording head,

wherein a length of the quantization pattern in the predetermined direction is different from an integer multiple of the first distance and is also different from one over an integer multiple of the first distance.

3. The image processing apparatus according to claim 2,

wherein the conveyance unit further conveys the recording medium in the predetermined direction by a second distance that is shorter than the first distance during the plurality of scanning operations of the recording head, and

wherein the length of the quantization pattern in the predetermined direction is different from an integer multiple of the second distance and is also different from one over an integer multiple of the second distance.

4. The image processing apparatus according to claim 3, wherein the conveyance unit conveys the recording medium by the first distance in a case where the recording head is located in a central part in the predetermined direction on the recording medium and conveys the recording medium by the second distance in a case where the recording head is located in an end part in the predetermined direction on the recording medium.

5. The image processing apparatus according to claim 1,

wherein a threshold for specifying ejection or non-ejection of the ink to each of the plurality of pixel areas is set with respect to each of the plurality of pixels in the dither pattern, and

wherein permission or prohibition of the ink ejection to each of the plurality of pixel areas is specified with respect to each of the plurality of pixels in each of the plurality of mask patterns.

6. The image processing apparatus according to claim 1,

wherein a threshold for specifying the number of times to perform the ink ejection to each of the plurality of pixel areas is set with respect to each of the plurality of pixels in the dither pattern, and

wherein the number of times to permit the ink ejection to each of the plurality of pixel areas is set with respect to each of the plurality of pixels in each of the plurality of mask patterns.

7. The image processing apparatus according to claim 1, wherein, in a case where a value indicated by the multi-value data is a first value, the dither pattern and a predetermined mask pattern among the plurality of mask patterns are determined in a manner that an arrangement of dots based on the recording data generated on the basis of the quantized data and the predetermined mask pattern does not exhibit white noise characteristics.

8. The image processing apparatus according to claim 7, wherein, in a case where the value indicated by the multi-value data is the first value, the dither pattern and the predetermined mask pattern are determined in a manner that the arrangement of the dots based on the recording data generated on the basis of the quantized data and the predetermined mask pattern does not exhibit red noise characteristics.

9. The image processing apparatus according to claim 8, wherein, in a case where the value indicated by the multi-value data is the first value, the dither pattern and the predetermined mask pattern are determined in a manner that the arrangement of the dots based on the recording data generated on the basis of the quantized data and the predetermined mask pattern exhibit blue noise characteristics.

10. The image processing apparatus according to claim 7, wherein, in a case where the value indicated by the multi-value data is a second value that is different from the first value, the dither pattern and the predetermined mask pattern are determined in a manner that the arrangement of the dots based on the recording data generated on the basis of the quantized data and the predetermined mask pattern does not exhibit the white noise characteristics.

11. The image processing apparatus according to claim 7, wherein, in a case where the value indicated by the multi-value data is the first value, the dither pattern and a second mask pattern that is different from the predetermined mask pattern among the plurality of mask patterns are determined in a manner that the arrangement of the dots based on the recording data generated on the basis of the quantized data and the second mask pattern does not exhibit the white noise characteristics.

12. The image processing apparatus according to claim 1, further comprising:

a memory that stores the dither pattern and the plurality of mask patterns.

13. The image processing apparatus according to claim 12,

wherein the memory further stores a plurality of mask pattern parts including the first part in the each of the plurality of mask patterns and the second part in the each of the plurality of mask patterns, and

the recording data are generated by using the plurality of mask pattern parts stored in the memory.

14. The image processing apparatus according to claim 12, wherein the plurality of mask patterns stored in the memory are divided to generate the plurality of mask pattern parts and the recording data are generated by using the plurality of generated mask pattern parts.

15. The image processing apparatus according to claim 1, wherein the dither pattern and each of the plurality of mask patterns have a mutually same size.

16. The image processing apparatus according to claim 1, further comprising:

the recording head.

18. The image processing apparatus according to claim 1, wherein the number of the pixel areas of the unit area corresponding to the conveyance amount is different from one over an integer multiple of the number of the pixel areas in the dither pattern in the predetermined direction.

19. The image processing apparatus according to claim 18,

wherein a second number of pixel areas of the unit area corresponding to a second conveyance amount between two sequential scanning operations is less than the number of the pixel areas of the unit area corresponding to the conveyance amount, and

wherein the second number of the pixel areas of the unit area corresponding to the second conveyance amount is different from an integer multiple of the number of the pixel areas in the dither pattern in the predetermined direction and is also different from one over an integer multiple of the number of the pixel areas in the dither pattern in the predetermined direction.

20. The image processing apparatus according to claim 19, wherein the conveyance amount is used for conveying the recording medium in a case where the recording head is located in a central part in the predetermined direction on the recording medium, and the second conveyance amount is used for conveying the recording medium in a case where the recording head is located in an end part in the predetermined direction on the recording medium.

17. An image processing method for generating recording data used for each of a plurality of relative scanning operations of a recording head in an intersecting direction that intersects with a predetermined direction with respect to a unit area on a recording medium, the recording head including an ejection opening column having a plurality of ejection openings for ejecting ink arranged in the predetermined direction, the recording data specifying ejection or non-ejection of the ink to each of a plurality of pixel areas in the unit area on a recording medium corresponding to a plurality of pixels of the recording data, the image processing method comprising:

at an image processing apparatus that includes one or more memories configured to store a dither pattern and a plurality of mask patterns corresponding to the plurality of relative scanning operations,

wherein each pixel area in the dither pattern has a respective threshold value for specifying ejection of ink to a corresponding pixel area on the recording medium,

wherein each pixel area in each of the plurality of mask patterns has respective information indicating permission or prohibition of ejection of ink to a corresponding pixel area on the recording medium,

wherein a number of pixel areas of the unit area corresponding to a conveyance amount between two sequential scanning operations is greater than a number of pixel areas in the dither pattern in the predetermined direction, the number of the pixel areas of the unit area corresponding to the conveyance amount being different from an integer multiple of the number of the pixel areas in the dither pattern in the predetermined direction, and

wherein the number of the pixel areas of the unit area corresponding to the conveyance amount is greater than a number of pixel areas in each of the plurality of mask patterns in the predetermined direction, the number of the pixel areas of the unit area corresponding to the conveyance amount being different from an integer multiple of the number of the pixel areas in the each of the plurality of mask patterns in the predetermined direction;

obtaining multi-value data corresponding to an image to be recorded in the unit area;

quantizing the multi-valued data by applying the dither pattern repeatedly in the predetermined direction to generate quantized data, wherein the quantizing the multi-valued data includes (i) generating a first area of the quantized data using a first part in the dither pattern without using a second part in the dither pattern, and (ii) generating a second area of the quantized data using the entire dither pattern, the second area of the quantized data being different from the first area of the quantized data; and

distributing the quantized data to the plurality of scanning operations by using the plurality of mask patterns to generate the recording data,

wherein each of the plurality of mask patterns is associated with the dither pattern, and

wherein the distributing the quantized data includes (i) applying, to the first area of the quantized data, a first part in each of the plurality of mask patterns without using a second part in the each of the plurality of mask patterns, and (ii) applying, to the second area of the quantized data, each of the plurality of mask patterns.