JP2009033239A5

JP2009033239A5 -

Info

Publication number: JP2009033239A5
Application number: JP2007192223A
Authority: JP
Filing date: 2007-07-24
Publication date: 2010-03-18
Anticipated expiration: 2027-07-24

Claims

A device for creating a color conversion lookup table for converting an input color coordinate system coordinate value into an ink color system ink amount composed of a plurality of types of ink including achromatic ink and chromatic ink. ,
A gray gradation characteristic generating unit that generates a gray gradation characteristic that expresses a gray gradation using only the achromatic ink;
As an initial value associated with each of a plurality of input color system color points that are predetermined color points of the input color system, an initial value of the ink color system and a device corresponding to the input color system An initial value setting unit for setting a device independent color system color point position which is a color point of the independent color system;
Ink of the ink color system corresponding to the plurality of device-independent color system color points after the smoothing process is executed while performing a process of smoothing the distribution of the plurality of device-independent color system color points from an initial position. A smoothing processing unit for determining the amount;
A table creation unit that creates a color conversion lookup table for converting the coordinate value of the input color system into the ink amount of the ink color system based on the result of the smoothing process;
With
For the input color system gray color point group, which is a set of color points expressed by the gray gradation, the table creation unit is a color based on the gray gradation characteristic generated by the gray gradation characteristic generation unit. A lookup table creation device for creating a conversion lookup table.

The lookup table creation device according to claim 1,
The ink color system includes a plurality of types of achromatic inks having different densities,
The gray-scale characteristic generation unit generates a gray-scale characteristic that expresses a gray gradation using only the plurality of types of achromatic inks.

The lookup table creation device according to claim 1 or 2, further comprising:
A color system conversion unit for converting the ink amount of the ink color system into a coordinate value of a device independent color system;
The initial value setting unit uses the color system conversion unit to convert the initial value of the ink color system associated with each of the plurality of input color system color points into the device independent color system. A lookup table creation device that determines initial positions of the plurality of device independent color system color points by converting them into coordinate values.

The lookup table creation device according to claim 3,
The smoothing processing unit and the initial value setting unit are:
(I) The initial value setting unit corresponds to the input color system gray color point group by referring to the gray gradation characteristics using the gray color value of the input color system gray color point group. Determining an ink amount of the achromatic ink;
(Ii) the initial value setting unit converting the ink amount of the achromatic ink into coordinate values of color points of the device independent color system using the color system conversion unit;
(Iii) The smoothing processing unit performs the smoothing on the color points of the device independent color system corresponding to the ink amount of the achromatic ink, thereby determining the position of the device independent color system gray color point group. And determining, using the color system conversion unit, an optimum value of the ink amount of the ink color system corresponding to the device independent color system gray color point group;
A look-up table creation device that executes local smoothing processing including:

The lookup table creation device according to claim 4,
In the local smoothing process relating to the input color system gray color point group, the smoothing processing unit is configured to perform the color specification for the paper black point having the highest density in the input color system gray color point group. A lookup table creation device that executes the local smoothing process so that a color point of the device independent color system corresponding to the paper black point is as dark as possible using a system conversion unit.

The lookup table creation device according to claim 5,
The input color system is the RGB color system,
The look-up table creation device, wherein the gray gradation in the color space of the input color system is in the vicinity of a straight line in which an R value, a G value, and a B value, which are three input values of the RGB color system, are equal to each other.

The lookup table creation device according to claim 4,
In the local smoothing process related to the input color system gray color point group, the smoothing processing unit is configured to perform the highest density gray point having the highest density in the input color system gray color point group. Ink amount of the ink color system corresponding to the highest density gray point obtained by referring to gray gradation characteristics, and the device independent color space obtained by conversion by the device independent color system conversion unit from the ink amount A look-up table creation device that executes the local smoothing process while restraining the position of a system color point from moving.

The lookup table creation device according to claim 7,
The input color system is the CMYK color system,
The lookup table creation device, wherein the gray gradation in the color space of the input color system is near the K axis of the CMYK color system.

The lookup table creation device according to claim 8, wherein
The input color system includes a plurality of K layers in which the K value is constant and the C value, the M value, and the Y value each take a value within a predetermined definition range,
The smoothing processing unit, for the color points other than the input color system gray color point group among the input color system color points on each K layer, the local color system related to the input color system gray color point group. The smoothing process is performed by allowing the change of the chromatic color ink amount while fixing the ink amount of the achromatic color among the ink amounts of the ink color system determined by the smoothing process. Uptable creation device.

The lookup table creation device according to any one of claims 1 to 9,
The smoothing processing unit
The color point on the outer shell surface of the three-dimensional color solid of the RGB color system or the color point on the outer shell surface of a plurality of three-dimensional color solids having a constant K value in the CMYK color system. Execution process,
After the smoothing process on the color points on the outer shell surface, the smoothing is performed on the other color points existing inside the outer shell surface while restraining the color points on the outer shell surface from moving. A lookup table creation device that executes processing.

A method for creating a color conversion lookup table for converting an input color system coordinate value into an ink color system ink amount composed of a plurality of types of ink including achromatic ink and chromatic ink. ,
(A) generating a gray gradation characteristic that expresses a gray gradation using only the achromatic ink;
(B) As an initial value associated with each of a plurality of input color system color points that are predetermined color points of the input color system, the initial value of the ink color system and the input color system A step of setting a device independent color system color point position which is a color point of a corresponding device independent color system;
(C) performing the process of smoothing the distribution of the plurality of device independent color system color points from the initial position, and the ink color corresponding to the plurality of device independent color system color points after the smoothing process; Determining a system ink amount, and creating a color conversion lookup table for converting the coordinate value of the input color system into the ink amount of the ink color system based on the result of the smoothing process; ,
With
The step (c) is based on the gray gradation characteristics generated by the gray gradation characteristic generation unit for the input color system gray color point group which is a set of color points expressed by the gray gradation. A lookup table creation method including a step of creating a color conversion lookup table.

Creates a color conversion lookup table to convert the input color system coordinate values into an ink color system ink amount composed of multiple types of ink including achromatic ink and chromatic ink. A program that
(A) the computer generating a gray gradation characteristic that expresses a gray gradation using only the achromatic ink; and
(B) The computer uses an initial value of the ink color system as an initial value associated with each of a plurality of input color systems color points that are predetermined color points of the input color system, and the input A step of setting a device independent color system color point position that is a color point of a device independent color system corresponding to the color system;
(C) The computer executes a process of smoothing the distribution of the plurality of device independent color system color points from an initial position, and corresponds to the plurality of device independent color system color points after the smoothing process. A color conversion lookup table for determining an ink amount of the ink color system and converting a coordinate value of the input color system into an ink amount of the ink color system based on a result of the smoothing process; Creating a process;
Is a program for causing the computer to execute
The step (c) is based on the gray gradation characteristics generated by the gray gradation characteristic generation unit for the input color system gray color point group which is a set of color points expressed by the gray gradation. A lookup table creation program including a step of creating a color conversion lookup table.