Convert a dot area ratio of a target process color using a fluorescent color for higher brightness and saturation

Patent metadata

Field	Value
Publication number	US-11818320-B2
Application number	US-202117230916-A
Country	US
Kind code	B2
Filing date	Apr 14, 2021
Priority date	Apr 17, 2020
Publication date	Nov 14, 2023
Grant date	Nov 14, 2023

Abstract

An image processing apparatus includes control circuitry. The control circuitry is configured to: acquire first image data to be subjected to color conversion; and convert the first image data acquired, into second image data in which a dot area ratio of a target process color of process colors indicated by the first image data is distributed into a distributed dot area ratio of a fluorescent color different from the target process color and a distributed dot area ratio of the target process color.

First claim

The invention claimed is:

1. An image processing apparatus, comprising control circuitry configured to:
acquire first image data to be subjected to color conversion, wherein the first image data comprises CMYK image data; and
convert the first image data into second image data in which a dot area ratio of a target process color of process colors indicated by the first image data is distributed into a distributed dot area ratio of a fluorescent color different from the target process color and a distributed dot area ratio of the target process color, wherein a ratio between the distributed dot area ratio of the fluorescent color and the distributed dot area ratio of the target process color in the second image data is (1−α):α (0<distribution factor α<1), where the dot area ratio of the target process color indicated by the first image data is 1;
wherein the target process color has a same color system as a color system of the fluorescent color;
wherein the dot area ratio of the target process color is included in a first profile in which color values of a color space are associated with dot area ratios of the process colors;
wherein the control circuitry is configured to:
generate a second profile in which a combination of the distributed dot area ratio of the target process color and the distributed dot area ratio of the fluorescent color is associated with the color values of the color space;
convert the dot area ratios of the process colors indicated by the first image data to converted color values of the color space using the first profile; and
convert the converted color values to the dot area ratios of the process colors, including the distributed dot area ratio of the target process color and the distributed dot area ratio of the fluorescent color, using the second profile, to convert the first image data into the second image data.

2. The image processing apparatus according to claim 1 ,
wherein the target process color has an absorption spectrum peak closest to an absorption spectrum peak of the fluorescent color among the process colors.

3. The image processing apparatus according to claim 1 ,
wherein the distribution factor α is a fixed value.

4. The image processing apparatus according to claim 3 ,
wherein the distribution factor α is 0.4.

5. The image processing apparatus according to claim 1 ,
wherein the control circuitry is configured to calculate a saturation from a color value of the color space included in the first profile, and determine the distribution factor α according to the saturation.

6. An image processing apparatus, comprising control circuitry configured to:
acquire first image data to be subjected to color conversion; and
convert the first image data into second image data in which a dot area ratio of a target process color of process colors indicated by the first image data is distributed into a distributed dot area ratio of a fluorescent color different from the target process color and a distributed dot area ratio of the target process color;
wherein the control circuitry is configured to calculate the distributed dot area ratio of the target process color and the distributed dot area ratio of the fluorescent color, using a distribution that changes based on a saturation indicated by the first image data within a predetermined range between a first predetermined saturation value and a second predetermined saturation value, the distribution factor having a positive correlation with the saturation
wherein the distribution factor is fixed outside of the predetermined range.

7. The image processing apparatus according to claim 6 , wherein the control circuitry is configured not to distribute the dot area ratio of the target process color to the distributed dot area ratio of the fluorescent color when the saturation is less than the first predetermined saturation value.

8. The image processing apparatus according to claim 6 ,
wherein the control circuitry is configured to derive the saturation directly from Lab values.

9. The image processing apparatus according to claim 1 ,
wherein the fluorescent color is fluorescent magenta.

10. An image processing method, comprising:
acquiring first image data to be subjected to color conversion, wherein the first image data comprises CMYK image data; and
converting the first image data to second image data in which a dot area ratio of a target process color of process colors indicated by the first image data is distributed into a distributed dot area ratio of a fluorescent color different from the target process color and a distributed dot area ratio of the target process color;
wherein a ratio between the distributed dot area ratio of the fluorescent color and the distributed dot area ratio of the target process color in the second image data is (1−α):α (0<distribution factor α<1), where the dot area ratio of the target process color indicated by the first image data is 1;
wherein the target process color has a same color system as a color system of the fluorescent color;
wherein the dot area ratio of the target process color is included in a first profile in which color values of a color space are associated with dot area ratios of the process colors;
wherein the converting further comprises:
generating a second profile in which a combination of the distributed dot area ratio of the target process color and the distributed dot area ratio of the fluorescent color is associated with the color values of the color space;
converting the dot area ratios of the process colors indicated by the first image data to converted color values of the color space using the first profile; and
converting the converted color values to the dot area ratios of the process colors, including the distributed dot area ratio of the target process color and the distributed dot area ratio of the fluorescent color, using the second profile.

11. A non-transitory storage medium storing computer-readable code which, when executed by one or more processors, cause the processors to execute:
acquiring first image data to be subjected to color conversion, wherein the first image data comprises CMYK image data; and
converting the first image data to second image data in which a dot area ratio of a target process color of process colors indicated by the first image data is distributed into a distributed dot area ratio of a fluorescent color different from the target process color and a distributed dot area ratio of the target process color;
wherein a ratio between the distributed dot area ratio of the fluorescent color and the distributed dot area ratio of the target process color in the second image data is (1−α):α (0<distribution factor α<1), where the dot area ratio of the target process color indicated by the first image data is 1;
wherein the target process color has a same color system as a color system of the fluorescent color;
wherein the dot area ratio of the target process color is included in a first profile in which color values of a color space are associated with dot area ratios of the process colors;
wherein the converting further comprises:
generating a second profile in which a combination of the distributed dot area ratio of the target process color and the distributed dot area ratio of the fluorescent color is associated with the color values of the color space;
converting the dot area ratios of the process colors indicated by the first image data to converted color values of the color space using the first profile; and
converting the converted color values to the dot area ratios of the process colors, including the distributed dot area ratio of the target process color and the distributed dot area ratio

Assignees

• Matsushima Yuki
• Sawada Takuroh
• Ricoh Co Ltd

Inventors

• Matsushima Yuki
• Sawada Takuroh

Classifications

• H04N1/6025 Primary

  using look-up tables · CPC title

• G01J3/52

  using colour charts · CPC title

• H04N1/6008 Primary

  with primary colour signals, e.g. RGB or CMY(K) · CPC title

• H04N1/54 Primary

  Conversion of colour picture signals to a plurality of signals some of which represent particular mixed colours, e.g. for textile printing · CPC title

• H04N1/6075

  Corrections to the hue · CPC title