Image processing apparatus, method, and product for reducing color unevenness based on edge information

Patent metadata

Field	Value
Publication number	US-11247482-B2
Application number	US-202016929792-A
Country	US
Kind code	B2
Filing date	Jul 15, 2020
Priority date	Jul 31, 2019
Publication date	Feb 15, 2022
Grant date	Feb 15, 2022

Abstract

An image processing apparatus includes a processing unit that converts first input image data for a first region and second input image data for a second region to reduce a difference between first region recorded image density and second region recorded image density, and generates dot position data of a dot to be generated in each of the first and second regions based on the dot data after the conversion processing. The acquisition unit acquires edge information indicating a first object pixel edge of an image pixel for the first region and a second object pixel edge of an image pixel for the second region. Based on the acquired edge information, conversion and generation processing are performed in such a manner that a color signal of an edge pixel is increased/reduced to a degree lower than a degree to which a color signal of a non-edge object pixel is increased/reduced.

First claim

What is claimed is:

1. An image processing apparatus, wherein the image processing apparatus is configured to perform image processing for recording an image in a first region on a recording medium using a first nozzle group including a part of a plurality of nozzles arranged in a nozzle array in which the plurality of nozzles are configured to provide ink, and to perform image processing for recording an image in a second region different from the first region using a second nozzle group including a nozzle different from the part of the plurality of nozzles in the first nozzle group, the image processing apparatus comprising:
a processing unit configured to perform conversion processing to convert first input data of the image to be recorded in the first region and second input data of the image to be recorded in the second region to reduce a difference between a density of the image recorded in the first region using the first nozzle group with respect to an input of a predetermined color signal and a density of the image recorded in the second region using the second nozzle group with respect to the input of the predetermined color signal, and configured to perform generation processing for generating dot data indicating a position of a dot to be generated in each of the first region and the second region based on the dot data after the conversion processing; and
an acquisition unit configured to acquire edge information indicating a pixel corresponding to a first edge of an object in the image to be recorded in the first region and indicating a pixel corresponding to a second edge of the object in the image to be recorded in the second region,
wherein, based on the acquired edge information, the processing unit performs the conversion processing and the generation processing in such a manner that a color signal of an edge pixel corresponding to an edge is increased/reduced to a degree lower than a degree to which a color signal of a non-edge pixel corresponding to a non-edge of the object is increased/reduced.

2. The image processing apparatus according to claim 1 , wherein, in a case where a conversion for outputting a color signal having a value smaller than a value of the input predetermined color signal is carried out in the conversion processing, the processing unit performs conversion processing to convert data, from data on the edge pixel and indicating that the dot is not generated, to data indicating that the dot is generated by the generation processing based on the converted data and the acquired edge information.

3. The image processing apparatus according to claim 1 , wherein the processing unit performs processing such that the edge pixel in an output color signal has a value greater than a value of the non-edge pixel in a case where a conversion by the conversion processing for outputting a color signal having a value smaller than a value of the input predetermined color signal is carried out based on the acquired edge information.

4. The image processing apparatus according to claim 1 , wherein the edge information is acquired based on data before the conversion processing is carried out by the conversion unit.

5. The image processing apparatus according to claim 1 , wherein the processing unit performs conversion processing to convert data of the image to be recorded in the first region based on information indicating an ejection characteristic of the first nozzle group and convert data of the image to be recorded in the second region based on information indicating an ejection characteristic of the second nozzle group.

6. The image processing apparatus according to claim 5 , wherein the information indicating the ejection characteristic of the first nozzle group is acquired based on a result of measurement of a measurement image recorded using the first nozzle group, and the information indicating the ejection characteristic of the second nozzle group is acquired based on a result of measurement of the measurement image recorded using the second nozzle group.

7. The image processing apparatus according to claim 1 , wherein the conversion processing unit converts data, from data on the edge pixel and indicating that the dot is not generated, to data indicating that the dot is generated in the generation processing with a predetermined probability.

8. The image processing apparatus according to claim 1 , wherein data output from the conversion processing is ternary or more multi-valued data.

9. The image processing apparatus according to claim 1 , wherein the part of the plurality of nozzles in the first nozzle group is not included in the second nozzle group.

10. The image processing apparatus according to claim 1 , further comprising a recording head provided with a nozzle array including the first nozzle group and the second nozzle group.

11. A method for an image processing apparatus, wherein the image processing apparatus is configured to perform image processing for recording an image in a first region on a recording medium using a first nozzle group including a part of a plurality of nozzles arranged in a nozzle array in which the plurality of nozzles are configured to provide ink, and to perform image processing for recording an image in a second region different from the first region using a second nozzle group including a nozzle different from the part of the plurality of nozzles in the first nozzle group, the method comprising:
performing conversion processing to convert first input data of the image to be recorded in the first region and second input data of the image to be recorded in the second region to reduce a difference between a density of the image recorded in the first region using the first nozzle group with respect to an input of a predetermined color signal and a density of the image recorded in the second region using the second nozzle group with respect to the input of the predetermined color signal, and performing generation processing for generating dot data indicating a position of a dot to be generated in each of the first region and the second region based on the dot data after the conversion processing; and
acquiring edge information indicating a pixel corresponding to a first edge of an object in the image to be recorded in the first region and indicating a pixel corresponding to a second edge of the object in the image to be recorded in the second region,
wherein, based on the acquired edge information, processing includes performing the conversion processing and performing the generation processing in such a manner that a color signal of an edge pixel corresponding to an edge is increased/reduced to a degree lower than a degree to which a color signal of a non-edge pixel corresponding to a non-edge of the object is increased/reduced.

12. The method according to claim 11 , wherein, in a case where a conversion for outputting a color signal having a value smaller than a value of the input predetermined color signal is carried out in the conversion processing, performing includes performing conversion processing to convert data, from data on the edge pixel and indicating that the dot is not generated, to data indicating that the dot is generated by the generation processing based on the converted data and the acquired edge information.

13. The method according to claim 11 , wherein performing includes performing processing such that the edge pixel in an output color signal has a value greater than a value of the non-edge pixel in a case where a conversion by the conversion processing for outputting a color signal having a value smaller than a value of the input predetermined color signal is carried out based on the acquired

Assignees

• Canon Kk

Inventors

• Nakagawa Junichi
• Yanai Yumi

Classifications

• G06K15/027

  Test patterns and calibration (arrangements for controlling or analysing printing mechanisms of typewriters or selective printing units B41J29/393 takes precedence; colour correction using test pattern analysis in general H04N1/6033) · CPC title

• B41J2/2139 Primary

  Compensation for malfunctioning nozzles creating dot place or dot size errors (generating single droplets or particles on demand by pressure, e.g. electromechanical transducers B41J2/045) · CPC title

• G06K15/1874

  with provisions for treating some of the print data differently · CPC title

• H04N1/605

  for controlling ink amount, strike-through, bleeding soakage or the like · CPC title

• H04N1/6033

  using test pattern analysis (H04N1/6055 takes precedence) · CPC title