PRINTING METHOD, PRINTING APPARATUS, CORRESPONDING TABLE CREATING METHOD AND PROGRAMS

• US 20090225379A1
• Filed: 01/28/2009
• Published: 09/10/2009
• Est. Priority Date: 01/28/2008
• Status: Active Grant

• Current Assignee: Seiko Epson Corporation (Seiko Group)
• Original Assignee: Seiko Epson Corporation (Seiko Group)
• Inventors: Maki, Yoichiro
• Granted Patent: US 8,040,563 B2
• Time in Patent Office: Days
• US Class Current: 358/520
• CPC Class Codes: H04N 1/6025 using look-up tables
• CPC Class Codes: H04N 1/6072 adapting to different types of images, e.g. characters, graphs, black and white image portions

Abstract

A method for printing an image includes: generating a third table in which a second table, indicating a relationship between one of a plurality of brightness values and an amount of ink of an achromatic color for representing the one of the brightness values, is embedded in the first table, indicating a relationship between a color defined by each of the first lattice points and amounts of the ink of the achromatic color and ink of chromatic colors; converting first RGB components of the image data corresponding to a character area into the RGB components defined by the some of the lattice points based on brightness values of the RGB components of the image data, thereby generating modified image data; converting the RGB components of the modified image data into amounts of the ink o; and printing the image in accordance with the converted amounts.

Claims

1. A method for printing an image by using ink of at least one achromatic color and at least three chromatic colors based on RGB image data obtained from a printed image, the method comprising:

setting a plurality of first lattice points in an RGB color solid defined by RGB components of the RGB image data;

storing a first table indicating a relationship between a color defined by each of the first lattice points and amounts of the ink of the achromatic color and the ink of the chromatic colors;

storing a second table indicating a relationship between one of a plurality of brightness values and an amount of the ink of achromatic color for representing the one of the brightness values;

storing information indicating a relationship between the brightness values and some of the first lattice points located at a ridge area including a ridge line of the RGB color solid at which two of the RGB components take either maximum values or minimum values thereof;

generating a third table in which the second table is embedded in the first table based on the information;

extracting a character area in which a character is printed from the printed image;

converting first RGB components of the image data corresponding to the extracted character area into the RGB components defined by the some of the lattice points based on brightness values of the RGB components of the image data, thereby generating modified image data;

converting the RGB components of the modified image data into amounts of the ink of a chromatic color and the ink of chromatic colors based on the third table; and

printing the image in accordance with the converted amounts of the ink of achromatic color and the ink of chromatic colors.

2. The method according to claim 1, wherein

in a case where second RGB components of image data corresponding to an area other than the character area are located within the ridge area, the second RGB components are converted into third RGB components located outside of the ridge area.

3. The method according to claim 1, wherein

the two of the RGB components are an R component and a G component.

6. A computer program product storing a computer program configured to causing a computer to execute the method as set forth in claim 1.

4. A printing apparatus for printing an image by using ink of at least one achromatic color and at least three chromatic colors based on RGB image data obtained from a printed image, the printing apparatus comprising:

a first storage, configured to set a plurality of first lattice points in an RGB color solid defined by RGB components of the RGB image data, and configured to store a first table indicating a relationship between a color defined by each of the first lattice points and amounts of the ink of the achromatic color and the ink of the chromatic colors;

a second storage, configured to store a second table indicating a relationship between one of a plurality of brightness values and an amount of the ink of achromatic color for representing the one of the brightness values;

a third storage, configured to store information indicating a relationship between the brightness values and some of the first lattice points located at a ridge area including a ridge line of the RGB color solid at which two of the RGB components take either maximum values or minimum values thereof;

a generator, configured to generate a third table in which the second table is embedded in the first table based on the information;

a extractor, configured to extract a character area in which a character is printed from the printed image;

a first converter, configured to convert first RGB components of the image data corresponding to the extracted character area into the RGB components defined by the some of the lattice points based on brightness values of the RGB components of the image data, thereby generating modified image data,

a second converter, configured to convert the RGB components of the modified image data into amounts of the ink of achromatic color and the ink of chromatic colors based on the third table; and

a printer, configured to print the image in accordance with the converted amounts of the ink of achromatic color and the ink of chromatic colors.

5. A method for creating a table indicating a relationship between first gradation values and second gradation values, the first gradation values including at least one achromatic color component and at least three chromatic color components used in printing an image, the second gradation values including RGB respective components, the method comprising:

setting a plurality of first lattice points in an RGB color solid defined by RGB components;

storing a first table indicating a relationship between a color defined by each of the first lattice points and the first gradation values;

storing a second table indicating a relationship between one of a plurality of brightness values and a gradation value of the achromatic color component for representing the one of the brightness values;

storing information indicating a relationship between the brightness values and some of the first lattice points located at a ridge area including a ridge line of the RGB color solid at which two of the RGB components take either maximum values or minimum values thereof; and

generating a third table in which the second table is embedded in the first table based on the information.

7. A computer program product storing a computer program configured to causing a computer to execute the method as set forth in claim 5.