JP2003289446A - Method, apparatus and program for providing color reproduction characteristic - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color reproduction characteristics providing method, and a color reproduction characteristics providing apparatus capable of providing color reproduction characteristics by using an optional color chart, and a color reproduction characteristics providing program which makes a computer function like the color reproduction characteristics providing apparatus. <P>SOLUTION: Coordinates equivalent to respective grating points of first and second gratings are extracted from a plurality of coordinates denoted by a plurality of acquired pairs of data. A grating point having no coordinates represented by a pair of data corresponding to the coordinates equivalent to grating points is interpolated on the basis of the coordinates equivalent to the grating point of the first grating. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color reproduction characteristic creating method, a color reproduction characteristic creating apparatus, and a computer for creating a color reproduction characteristic representing a correspondence between coordinates in a device-dependent color space and device-independent colorimetric values. The present invention relates to a color reproduction characteristic creating program for operating the above as a color reproduction characteristic creating apparatus.

[0002]

2. Description of the Related Art Conventionally, an image (hereinafter referred to as an original image) is captured by an input device such as a color scanner or an electronic still camera to obtain image data, and based on the image data, a printing machine, a printer, or the like is used. The original image is reproduced by an output device such as a display screen to obtain a reproduced image. In this case, a color reproduction characteristic (profile) that associates the color on the original image with the color expression in the image data according to the input device, and the color expression and reproduction in the image data according to the output device such as a printing machine or a printer. The color reproduction characteristics (profile) that correlate with the colors on the image are obtained, and the image data obtained from the original image with the input device is converted into image data suitable for the output device based on both color reproduction characteristics (profile). The converted image is converted and the reproduced image is output based on the image data for the output device. By doing so, it is possible to obtain a reproduced image whose color matches the original document image.

The same is true between output devices. Next, an example thereof will be described.

Conventionally, in printing a color image using a printing machine, before printing, a color printer or the like was used to make the color of the image printed by the printing machine resemble the same color as possible. Proof images are being created. When creating a proof image with a printer, output the proof image and the color reproduction characteristics (print profile) that describes the relationship between the image data and the color of the actual printed material, corresponding to the printing machine that is going to print. The color reproduction characteristic (printer profile) that describes the relationship between the image data and the color of the proof image that is actually printed out, corresponding to the specified printer, and prints based on these print profiles and printer profile. Image data is converted into image data for a printer, and a proof image is created based on the converted image data for the printer. By doing so, it is possible to create a proof image whose color matches the actual printed matter.

In order to obtain a color-matched image as described above, the color reproduction characteristics (profile) of an input device such as a color scanner or an electronic still camera or an output device such as a printing machine or a printer are accurately measured. Need to ask. In obtaining the color reproduction characteristics (profile), for example, in the case of an input device, a color chart in which color patches are arranged is read by the input device and converted into image data, and a color space (device-dependent color) on the image data is read. Space; for example, C (Cyan: cyan), M (Magenta: magenta), Y (Yel)
4 for low: yellow) and K (black: black)
CMYK color space consisting of colors, or R (Red:
Red), G (Green: green), and B (Blue:
Coordinates (CMYK) of RGB color space consisting of 3 colors of (blue)
Value or RGB value), and the same color chart is measured with a spectrophotometer to measure color space (device-independent color space; for example, L ^* a ^* b ^* color space or X
Colorimetric value (L ^* a ^* b ^* value or XYZ of YZ color space)
Values, etc.) and the coordinates in the device-dependent color space and the colorimetric values in the device-independent color space are associated with each other to obtain the color reproduction characteristic (profile) of the input device.

Further, in obtaining the color reproduction characteristic (profile) of the output device, image data corresponding to a color chart in which color patches are arranged is created, and the color chart is output by the output device based on the image data. , The color chart is measured with a spectrophotometer,
By associating the coordinates of the color space (device-dependent color space) on the image data thus obtained with the colorimetric values of the colorimetric color space (device-independent color space), the color reproduction characteristics (profile ) Is required.

[0007]

However, in the color patches constituting the color chart used for obtaining the color reproduction characteristics (profile) of the input device and the output device in this way, there are colors that the user considers to be important. If it is not included, even if the image data is converted based on the color reproduction characteristic (profile), there is a possibility that the color considered important by the user may not be faithfully reproduced in the reproduced image or the proof image.

Therefore, the user changes the color patch into a color patch containing a color that the user considers important, and the color reproduction characteristic (profile) is determined based on the color chart in which the changed color patch is arranged. make,
If the image data is converted based on the color reproduction characteristic (profile), it is expected that colors that the user considers important in the reproduced image and the proof image will be faithfully reproduced.

However, the conventional color chart in which the color patches are arranged, which is used in obtaining the color reproduction characteristics (profile) of the above-mentioned input device and output device, has an ICC (International) chart.
Color Consortium: OS (OperationSy) advocated by the International Color Consortium
system) Standard color reproduction characteristics (profile) in the printing industry such as ICC profile conforming to the environment-independent color reproduction characteristics (profile) standard.
Is a color chart according to a conventional creation procedure that assumes creation of a color reproduction characteristic (profile) used for a specific device in conformity with a device manufacturer's own standard.

Therefore, the above-mentioned color chart after being changed in consideration of faithful reproduction of the color that the user thinks is important is different from the color chart assuming the above-described specific preparation procedure. Therefore, even if an attempt is made to create a color reproduction characteristic (profile) based on such a color chart and the specific creation procedure described above, the color measurement color space (device There arises a problem that it is impossible to create a color reproduction characteristic (profile) in which a colorimetric value of an independent color space is reflected.

In view of the above circumstances, the present invention provides a color reproduction characteristic creating method, a color reproduction characteristic creating apparatus, and a computer capable of creating color reproduction characteristics using an arbitrary color chart. It is an object of the present invention to provide a color reproduction characteristic creating program that operates as a device.

[0012]

According to a method of creating a color reproduction characteristic of the present invention which achieves the above object, an image is represented by coordinates of a device-dependent color space in which colors are defined and having primary color coordinate axes respectively corresponding to a plurality of primary colors. Reproduction characteristics that create a color reproduction characteristic that represents the correspondence between the coordinates of the device-dependent color space and the device-independent colorimetric value that represents the color of the image in the device that mediates between the image data and the image In the creation method, each pair data acquisition step of acquiring a plurality of pair data representing a pair of coordinates of the device-dependent color space and the colorimetric value, and a plurality of pair data acquired in the pair data acquisition step. Of a plurality of coordinates represented by, a group of coordinates corresponding to all grid points of the first grid extending in a grid shape in the directions of the primary color coordinate axes of the plurality of primary colors and intersecting each other is extracted, and one of the coordinates is extracted. In the first grid setting step of setting each pair of colorimetric values for each of the coordinates as the colorimetric value associated with each of the group of coordinates by the color reproduction characteristic, and in the paired data acquisition step. Among the plurality of coordinates represented by the obtained plurality of paired data, there is a grid line that passes through the on-axis coordinates existing on the primary color coordinate axes, and extends in a grid shape in the direction of the primary color coordinate axes of each of the multiple primary colors to mutually extend. The coordinates corresponding to the grid points of the second grid intersecting with are extracted from the plurality of coordinates represented by the plurality of paired data, and each colorimetric value forming the pair with respect to the extracted coordinates is described as the color reproduction characteristic. In the second grid setting step of setting as the colorimetric value associated with the extracted coordinates, and among the coordinates corresponding to the grid points of the second grid, the plurality of paired data acquired in the paired data acquisition step are Excludes multiple coordinates to represent The colorimetric value associated is the color reproduction characteristics with respect to target, and having an interpolation process of setting obtained by interpolation based on the colorimetric value set by the first grating setup process.

Here, "the coordinates of the device-dependent color space" means, for example, a CM in the case where the device is an output device that outputs an image based on color data of four CMYK colors.
CMYK values in the color space defined by YK4 colors, or RG in the color space defined by RGB3 colors if the device is an input device that obtains RGB3 color data from an image
B value, etc., while "device-independent colorimetric value" does not depend on a specific device, for example, L ^* a ^* b ^*.
Value or XYZ value.

According to the color reproduction characteristic creating method of the present invention, the coordinates corresponding to the grid points of the first grid and the second grid are extracted from the plurality of coordinates represented by the plurality of acquired paired data, For a grid point having no coordinate represented by the paired data corresponding to the coordinate corresponding to the grid point, the grid point is interpolated based on the coordinate corresponding to the grid point of the first grid. In addition to the color chart for creating the prescribed color reproduction characteristics described in the section "Issue to be addressed", any color such as a color chart in which color patches containing colors that the user considers important is arranged. Even if an arbitrary color chart in which the patches are arranged is used, it is possible to create a color reproduction characteristic in which the colors of the arbitrary color patches are accurately reflected.

Here, in the color reproduction characteristic creating method of the present invention, the second grid setting step uses, as the on-axis coordinates, on-axis coordinates that regularly exist on the primary color coordinate axes. It may be.

Here, "regularly" means that, for example, the coordinate values of the coordinates on the regular axis form a geometric progression or geometric progression.

By using such regular on-axis coordinates as the on-axis coordinates, it is possible to obtain the same effects as the above-described effects, and it is possible to create color reproduction characteristics using an arbitrary color chart. it can.

In the color reproduction characteristic creating method of the present invention, the colorimetric value set in the interpolation step is corrected based on the colorimetric value set in the second grid setting step.
It is preferable to have a correction process of.

According to the color reproduction characteristic creating method having the first correction process, the influence of the color measurement value set in the second grid setting process is reflected in the color measurement value set in the interpolation process. Therefore, it is possible to create more accurate color reproduction characteristics.

Further, in the color reproduction characteristic creating method of the present invention, among the plurality of coordinates represented by the plurality of paired data acquired in the paired data acquisition process, the coordinates outside the grid point of the second grid are surrounded. The colorimetric value set in the interpolation process for the coordinates corresponding to the grid point of the second grid, and the pair of colorimetric values for the coordinates outside the grid point of the second grid It is also a preferable form to have a second correction process for correcting the above based on.

According to the color reproduction characteristic creating method having the second correction process as described above, among the coordinates represented by the paired data acquired in the paired data acquisition process, a pair of coordinates that deviates from the grid point is measured. Since the influence of the color value is reflected in the colorimetric value set in the interpolation process for the coordinates corresponding to the grid points surrounding the coordinate, all the paired data acquired in the paired data acquisition process was reflected. It is possible to create desired color reproduction characteristics with higher accuracy.

Further, the color reproduction characteristic creating apparatus of the present invention which achieves the above object, includes image data representing an image in coordinates of a device-dependent color space in which colors are defined, each having primary color coordinate axes corresponding to each of a plurality of primary colors. In a device that mediates between the image, in a color reproduction characteristic creating device that creates a color reproduction characteristic that represents a correspondence between coordinates of the device-dependent color space and a device-independent colorimetric value that represents the color of the image, Each is a pair data acquisition unit that acquires a plurality of pair data representing a pair of the device-dependent color space and the colorimetric value, and a plurality of pair data represented by the plurality of pair data acquired by the pair data acquisition unit. From the coordinates, a group of coordinates corresponding to all grid points of the first grid extending in a grid shape in the directions of the primary color coordinate axes of the plurality of primary colors and intersecting each other is extracted, and the coordinates of each group are extracted. A first grating setting unit for setting each colorimetric values to be paired, as colorimetric values the color reproduction characteristic is associated to each their group of coordinates with respect to,
Among the plurality of coordinates represented by the plurality of paired data acquired by the paired data acquisition unit, there is a grid line passing through the on-axis coordinates existing on the primary color coordinate axes, and in the direction of the primary color coordinate axes of the multiple primary colors. Coordinates corresponding to grid points of a second grid extending in a grid shape and intersecting each other are extracted from a plurality of coordinates represented by the plurality of paired data, and each colorimetric value forming the pair with respect to the extracted coordinates. Of the coordinates corresponding to the grid points of the second grid, which are acquired by the paired data acquisition section. Interpolation that obtains and sets the colorimetric values associated with the color reproduction characteristics with respect to the coordinates other than the plurality of coordinates represented by the plurality of paired data by interpolation based on the colorimetric values set by the first grid setting unit. And a section.

Further, the color reproduction characteristic creating program of the present invention which achieves the above object is executed in a computer, and the computer is operated to define a device-dependent color space having a primary color coordinate axis corresponding to each of a plurality of primary colors. Reproduction characteristics that represent the correspondence between the coordinates of the device-dependent color space and the device-independent colorimetric value that represents the color of the image in the device that mediates between the image data that represents the image with the coordinates of the image and the image. Is a color reproduction characteristic creation program that operates as a color reproduction characteristic creation apparatus that creates a plurality of paired data each representing a pair of coordinates of the device-dependent color space and the colorimetric value. Department,
Of the plurality of coordinates represented by the plurality of paired data acquired by the paired data acquisition unit, all the grid points of the first grid that extend in a grid shape in the direction of the primary color coordinate axes of the plurality of primary colors and intersect each other. A first group of coordinates is extracted, in which a corresponding group of coordinates is extracted, and each pair of colorimetric values corresponding to each group of coordinates is set as a colorimetric value that the color reproduction characteristic associates with each group of coordinates. Lattice setting unit, having a grid line passing through each axial coordinate existing on the primary color coordinate axis among the plurality of coordinates represented by the plurality of paired data acquired by the paired data acquisition unit, each of the plurality of primary colors The coordinates corresponding to the grid points of the second grid extending in the grid direction in the direction of the primary color coordinate axes and intersecting each other are extracted from the plurality of coordinates represented by the plurality of pair data, and the above pair is set to the extracted coordinates. Make each colorimetric value A second grating setting unit characteristic is set as the colorimetric value associate with the extracted coordinates, the second
Of the coordinates corresponding to the grid points of the grid of, the colorimetric value that the color reproduction characteristics correspond to the coordinates except the plurality of coordinates represented by the plurality of paired data acquired by the paired data acquisition unit,
And an interpolating unit that is obtained and set by interpolation based on the colorimetric values set by the first grid setting unit.

The reproduction characteristic producing apparatus and the color reproduction characteristic producing program of the present invention include all aspects corresponding to various aspects of the color reproduction characteristic producing method of the present invention.

Further, the color reproduction characteristic creating program of the present invention is configured such that, when the color reproduction characteristic creating program is installed in a computer and operated, the computer operates as the color reproduction characteristic creating apparatus of the present invention. It was done.

Although the same name is given to each component in the color reproduction characteristic creating device and the color reproduction characteristic creating program, those components mean hardware and software in the color reproduction characteristic creating device, The color reproduction characteristic creation program means only software.

[0027]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below.

In the present embodiment, in order to make the color on the proof image printed out by the color printer match or sufficiently approximate to the color on the printed matter obtained by the printing machine,
An example of creating a profile which is an example of the color reproduction characteristic according to the present invention will be described.

FIG. 1 is an overall configuration diagram of a printing and proof image creating system in which a profile created by the present invention is adopted. First, the positioning of the present invention will be described with reference to FIG.

In the color scanner 10, the original image 11 is read and C representing the read original image 11 is read.
(Cyan: cyan), M (Magenta: magenta), Y (Yellow: yellow), and K (Bl).
Color separated image data of four colors of ack: black) is generated. The CMYK image data is input to the workstation 20. At the workstation 20, an operator performs electronic plate-making on the basis of the input image data to generate image data representing an image for printing. The image data for printing is input to the film printer 30 when printing is performed, and in the film printer 30, C image corresponding to the input image data is displayed.
A printing film original plate of each MYK plate is created.

A printing plate is prepared from this printing film original plate, and the prepared printing plate is mounted on the printing machine 40.
Ink is applied to the printing plate mounted on the printing machine 40, and the applied ink is transferred onto a printing sheet to form a print image 41 on the sheet.

A series of operations for producing a film original plate by the film printer 30, further producing a printing plate, mounting it on the printing machine 40, applying ink to the printing plate, and printing on a sheet are a large-scale work. It is a work and costly.
Therefore, before the actual printing work is performed, the proof image 61 is created by the printer 60 as follows, and the finish of the printed image 41 is predicted in advance.

When creating a proof image, the image data created by electronic printing on the workstation 20 is input to the personal computer 50.
The image data input to the personal computer 50 is so-called PDL (Page Descr).
It is descriptive language data described in the option language, and in the personal computer 50, so-called RIP (Raster Image Proce) is used.
CMYK expanded into a bitmap by
Converted to image data of four colors. The CMYK four-color image data is substantially the same as the printing image data input to the film printer 30.

The spectrocolorimeter 70 and the personal computer 80 shown in FIG. 1 are related to the creation of a profile.
Using this personal computer 80, a LUT (Loo that has been created in advance by the color reproduction characteristic creating method of the present invention).
A profile having a format of (k Up Table) is stored. The CMYK four-color printing image data described above is referred to by its profile inside the personal computer 50, and the C color matching the printer 60 is obtained.
Converted to image data of four colors of MYK. The CMYK four-color image data for the printer is input to the printer 60, and the printer 60 creates a proof image 61 based on the input CMYK four-color image data for the printer.

Here, the degree of color matching between the image 41 obtained by printing by the printing machine 40 and the proof image obtained by the printer 60 is determined by the profile in the personal computer 50. This profile is created for each printing condition for each printer.

Although only one printing machine is shown in FIG. 1, a plurality of printing machines may exist, or even one printing machine has different printing conditions. Alternatively, the profile is created in accordance with each of a plurality of printing conditions including the difference between the printing machines. That is,
The profile is created according to a combination of each printing condition and each printer (each printing condition when one printer has a plurality of printing conditions). The method of creating this profile will be described later.

By creating a proof image and confirming the proof image in this manner, the finish of printing can be predicted in advance.

Here, the feature of the printing and proof image creating system shown in FIG. 1 as one embodiment of the present invention is related to the processing contents executed in the personal computer 80. The personal computer 80 will be described.

FIG. 2 is an external perspective view of a spectrocolorimeter 70 shown by a block in FIG. 1 and a personal computer 80 constituting one embodiment of a color reproduction characteristic creating apparatus of the present invention.
FIG. 3 is a hardware configuration diagram of the personal computer 80.

Here, this personal computer 8
0 hardware and OS (Operation S)
system) and the color reproduction characteristic creating program installed and executed in the personal computer 80 constitute one embodiment of the color reproduction characteristic creating apparatus of the present invention.

A color chart 90 in which a plurality of color patches are arranged is placed on the spectrocolorimeter 70 shown in FIG. 2, and a colorimetric value (L in this case is L for each of the plurality of color patches forming the color chart 90). ^* a ^* b ^* ) is measured. The color measurement data representing the color measurement value of each color patch obtained by the color measurement by the spectrocolorimeter 70 is
It is input to the personal computer 80 via the cable 91.

The color chart 90 is created by printing with the printing machine 40 shown by one block in FIG. 1 or by printout with the printer 60, and the personal computer 80 displays the color chart 90. The personal computer 80 knows the color data (coordinates in the device color space; each value of CMYK or RGB) corresponding to each color patch that constitutes the personal computer 80.
Then, a print profile or a printer profile is created based on the color data of each color patch of the color chart 90 and the color measurement data obtained by the spectrocolorimeter 70. A detailed explanation of this point will be given later, and here,
Next, the hardware configuration of the personal computer 80 will be described.

As shown in FIG. 2, the personal computer 80 has a body structure 81, an image display device 82 for displaying an image on a display screen 82a in accordance with an instruction from the body device 81, and a body device. 81, a keyboard 83 for inputting various information according to key operation, and
By designating an arbitrary position on the display screen 82a,
A mouse 84 for inputting an instruction corresponding to, for example, an icon displayed at that position at the time of designation is provided.
This body device 81 has an FD loading port 81a for loading a flexible disk (FD) and a C externally.
CD-ROM loading port 81b for loading D-ROM
Have.

As shown in FIG. 3, a CPU 811, which executes various programs, and a program stored in the hard disk drive 813, which is read out from the main unit 81 and expanded for execution by the CPU 811, are stored in the main memory 81.
2. A hard disk device 813 in which various programs and data are stored, an FD drive 814 for loading the FD 100 and accessing the loaded FD 100, a CD-
The ROM 110 is loaded, and the loaded CD-ROM
A CD-ROM drive 815 that accesses 110, and an I / O interface 8 that is connected to the spectrocolorimeter 70 shown in FIGS. 1 and 2 and receives colorimetric data from the spectrocolorimeter 70.
16 is built in, and these various elements, and the image display device 82, keyboard 83, and mouse 84 which are also shown in FIG. 2 are connected to each other via a bus 85.

Here, the CD-ROM 110 stores a color reproduction characteristic creating program for operating the personal computer 80 as a color reproduction characteristic creating apparatus, and the CD-ROM 110 is loaded into the CD-ROM drive 815. The color reproduction characteristic creating program stored in the CD-ROM 110 is uploaded to the personal computer 80, and the hard disk device 8
13 is stored.

Next, a basic profile creating method will be described.

First, a method of creating a print profile will be described.

In the workstation 20 shown in FIG. 1, C which is sequentially changed to 0%, 10%, ..., 100%, for example.
Halftone dot data of four colors of MYK are generated, and a color chart 90 (see FIG. 2) based on the halftone dot data thus generated is created according to the printing procedure described above. The image 41 shown in FIG. 1 is not an image showing a color chart, but instead of this image 41, the color chart 9 shown in FIG.
It is assumed that the same color chart as 0 is printed, and each color patch forming the color chart is measured by the spectrocolorimeter 7
The color is measured at 0. By doing so, the CMYK values on CMYK4 colors of the color space, L ^* a ^* b ^* in the color space L ^* a ^* b ^*
A print profile that represents the correspondence with the values is constructed.

FIG. 4 is a conceptual diagram of a print profile.

Image data defined by CMYK is input to this print profile, and the image data of CMYK is converted into image data defined by L ^* a ^* b ^* . Here, the print profile for converting the image data defined by CMYK into the image data defined by L ^* a ^* b ^* is represented by T.

Next, a method of creating a printer profile will be described.

The method of creating this printer profile is as follows:
The method is the same as the method for creating a print profile, except that the output device that outputs the color chart is a printer, not a printing machine. That is, here, in the personal computer 50 shown in FIG.
The data is sequentially changed to 0%, 10%, ..., 100% for each color, the dot% data generated in this manner is sent to the printer 60, and the printer 60 prints out a color chart based on the dot% data. . The image 61 shown in FIG. 1 is not an image showing a color chart, but in the printer 60, instead of this image 61, for example, a color chart created by printing with the printing machine 40 to create a print profile. It is assumed that the same type of color chart is output, and the color patches constituting the color chart are measured by the spectrocolorimeter 70. By doing this, the CMYK
And CMYK values in a color space color 4, printer profile representing the correspondence between the L ^* a ^* b ^* values of the L ^* a ^* b ^* color space is constructed.

FIG. 5 is a conceptual diagram of a printer profile.

This printer profile contains CMYK
Is input, and the CMYK dot% data is converted into L ^* a ^* b ^* colorimetric data. Here, a printer profile (forward conversion printer profile) for converting the CMYK halftone data to L ^* a ^* b ^* colorimetric data is represented by P, and its inverse conversion, that is, L ^* a ^* b ^*.
The printer profile (reverse conversion printer profile) for converting the color measurement data of CMYK halftone data to P ^-1
It is represented by.

Although the printer 60 is described here as a printer that outputs an image based on CMYK halftone data, for example, a printer that outputs an image based on RGB data can also be used by the personal computer 50. , By generating the data defined in the RGB space and outputting the color chart, it is possible to similarly create a printer profile suitable for the printer.

However, it is assumed here that the printer 60 that outputs an image based on the CMYK halftone dot data is used.

FIG. 6 is a diagram showing a profile in which the print profile and the printer profile are combined.

With this profile, the CMYK halftone data for printing is converted into L ^* a ^* b ^* colorimetric data by the print profile T, and then the L ^* a ^* b ^* colorimetric data is inversely converted by a printer. It is converted into CMYK halftone dot data for the printer by the profile P ^-1 . Based on the CMYK halftone dot data for the printer thus generated, the printer 60 can output the proof image of the same color as the printing. The profile formed by combining the print profile T and the inverse conversion printer profile P ^-1 is for converting the image data defined in the CMYK color space for printing into the image data defined in the CMYK color space for the printer. is there.

Such a profile is created by the personal computer 80 constituting the printing and proof image creating system shown in FIG. 1, and the created profile is stored in the personal computer 50 constituting the printing and proof image creating system shown in FIG. After installation, the image data described in PDL input from the workstation 20 is converted into CMYK image data, and then the CMYK image data for printing is converted into CMYK image data for the printer using the profile. CMYK for the printer
By printing out an image based on the image data of, a proof image for the printed image is created.

However, as described in the section "Problems to be solved by the invention", the color patches that constitute the conventional color chart used for creating a profile include colors that the user considers important. If not, even if the image data is converted based on the profile, there is a possibility that the color that the user considers important in the reproduced image or the proof image may not be faithfully reproduced.

As described above, the conventional color chart is created on the basis of the dot% data of four CMYK colors which are sequentially changed to 0%, 10%, ..., 100%. The net% data is not freely selectable by the profile creator, but depends on the program tailored to the specific profile creation procedure. Therefore, a color chart in which the colors and positions of the color patches that make up the color chart are changed, for example, a color chart in which color patches that include colors that the user considers important are arranged, is different from the color chart that assumes a specific creation procedure. Even if an attempt is made to create a profile based on such a color chart and the specific creation procedure described above, the L ^* a ^* b ^* color space obtained by measuring the color chart is different. There arises a problem that a profile in which the above L ^* a ^* b ^* values are reflected cannot be created.

Therefore, next, the color reproduction characteristic creating method of the present invention, which is carried out by using the personal computer 80 shown in FIGS. 1, 2 and 3, can create a profile using an arbitrary color chart. One embodiment will be described.

FIG. 7 is a flow chart showing an embodiment of the color reproduction characteristic creating method of the present invention.

This color reproduction characteristic creating method is performed by using CMYK values (an example of coordinates of the device-dependent color space referred to in the present invention) of four CMYK color spaces and L ^* a ^* b ^* on the L ^* a ^* b ^* color space. ^A method for creating a color reproduction characteristic that creates a profile that represents a correspondence with a ^* value (an example of a device-independent colorimetric value according to the present invention), which is a data acquisition step (step S1) and a basic grid setting step (step). S2), unit grid setting step (step S3), interpolation step (step S4), first correction step (step S5), and second correction step (step S6).

Details of each step of the color reproduction characteristic creating method shown in FIG. 7 will be described later.

FIG. 8 is a diagram showing an embodiment of the color reproduction characteristic creating program of the present invention.

The color reproduction characteristic creating program 210 shown in FIG. 8 is stored in the CD-ROM 110 shown in FIG.

This color reproduction characteristic creating program 210
It is executed in the personal computer 80 shown in FIG. 1, FIG. 2 and FIG.
YK4 colors CMYK values of the color space (an example of coordinates of device dependent color space referred to in the present invention), L ^* a ^* b ^* in the color space L ^*
It is a color reproduction characteristic creating program that operates as a color reproduction characteristic creating apparatus that creates a profile showing a correspondence with a ^* b ^* values (an example of device-independent colorimetric values according to the present invention). The color reproduction characteristic creation program 210 includes a paired data acquisition unit 211, a basic grid setting unit 212, a unit grid setting unit 213, an interpolation unit 214, and a first correction unit 215.
And a second correction unit 216.

A pair data acquisition section 211, a basic grid setting section 212, which constitutes the color reproduction characteristic creating program 210,
Unit grid setting unit 213, interpolation unit 214, first correction unit 2
15 and each element of the second correction unit 216 are as shown in FIG. 7 when the color reproduction characteristic creating program 210 is installed and executed in the personal computer 80 shown in FIGS. 1, 2 and 3. In the color reproduction characteristic creating method shown, each pair of data acquisition process (step S
1), basic grid setting process (step S2), unit grid setting process (step S3), interpolation process (step S4),
It is each program part that executes the processing of each element of the first correction process (step S5) and the second correction process (step S6).

Detailed description of each element of the color reproduction characteristic creating program 210 will be given later.

FIG. 9 is a functional block diagram showing an embodiment of the color reproduction characteristic creating apparatus of the present invention.

The color reproduction characteristic creating apparatus 300 shown in FIG.
Is a personal computer 8 shown in FIGS. 1, 2 and 3.
0 is installed with the color reproduction characteristic creation program 210 shown in FIG.
Are implemented in the personal computer 80.

Color reproduction characteristic creating apparatus 300 shown in FIG.
Is a CMYK value in the CMYK four color space (an example of coordinates of the device-dependent color space in the present invention) and an L ^* a ^* b ^* value in the L ^* a ^* b ^* color space (device non-reference in the present invention). A color reproduction characteristic creating device for creating a profile representing a correspondence with an example of a dependent colorimetric value, which comprises:
The basic grid setting unit 312, the unit grid setting unit 313, the interpolation unit 314, the first correction unit 315, and the second correction unit 3
And 16 are provided.

A pair data acquisition section 311, a basic grid setting section 312, which are provided in the color reproduction characteristic creating apparatus 300,
Unit grid setting unit 313, interpolation unit 314, first correction unit 3
15 and each element of the second correction unit 316 are a paired data acquisition unit 211 as a software component that constitutes the color reproduction characteristic creation program 210 shown in FIG.
The basic lattice setting unit 212, the unit lattice setting unit 213, the interpolation unit 214, the first correction unit 215, and the second correction unit 21.
6 and the combination of the hardware of the personal computer 80 shown in FIGS. 1, 2 and 3 and the OS and application programs necessary for realizing the respective functions of the software components. .

Next, each step of the color reproduction characteristic creating method shown in FIG. 7 and the color reproduction characteristic creating program 210 shown in FIG.
Each of the program parts and each element of the color reproduction characteristic creating device 300 shown in FIG. 9 will be described.

Each program component of the color reproduction characteristic creating program 210 shown in FIG. 8 and each element of the color reproduction characteristic creating apparatus 300 shown in FIG. 9 have a one-to-one correspondence with each step of the color reproduction characteristic creating method shown in FIG. It corresponds to
Each step of the color reproduction characteristic creating method shown in FIG. 7 will be described to explain each program component of the color reproduction characteristic creating program 210 shown in FIG. 8 and each element of the color reproduction characteristic creating apparatus 300 shown in FIG. Will also serve as the explanation.

In the pair-data acquisition step (step S1) of the color reproduction characteristic creating method shown in FIG. 7, a color chart is constructed with colors that the user considers important, such as the color of human skin, when creating a profile. In order to include in the color patch, first, halftone% data of four colors of CMYK in which halftone% is changed at an arbitrary ratio is generated, and a color chart based on the halftone data thus generated is created. Next, the color chart is subjected to color measurement by the spectrocolorimeter 70 shown in FIGS.
CMYK color value of the color space (an example of coordinates of device dependent color space referred to in the present invention), L ^* a ^* b ^* in the color space L ^* a ^* b ^*
A plurality of pair data representing a pair with a value (an example of a device-independent colorimetric value according to the present invention) is acquired.

Here, in the basic profile creating method described with reference to FIGS. 4 to 6, a color chart depending on a program adapted to a specific creating procedure of the profile is displayed by the spectrocolorimeter 70. The color is measured. Since a plurality of paired data representing a pair of CMYK values and L ^* a ^* b ^* values obtained by measuring the color of this conventional color chart form a predetermined grid, this grid is used. As a premise, it is possible to create a profile that represents the correspondence between CMYK values and L ^* a ^* b ^* values.

However, in the pair data acquisition process (step S1) of the color reproduction characteristic creating method shown in FIG. 7, an arbitrary color chart that the user considers important is measured by the spectrocolorimeter 70 shown in FIGS. Since a plurality of paired data representing a pair of CMYK value and L ^* a ^* b ^* value is acquired by being colored, a plurality of paired data is acquired. The illustrated personal computer 80 cannot recognize the grid based on the plurality of paired data.

Therefore, in the following, the basic lattice setting process (step S2) and the unit lattice setting process (step S3).
A method for creating a profile based on a plurality of paired data acquired in the paired data acquisition process (step S1) by setting a predetermined lattice in step S1 will be described.

It should be noted that the printer 60 shown in FIG. 1 used for creating a proof image in this embodiment is CMY.
Although the printer outputs an image based on K halftone data, generally, the halftone data in each axial direction of the C-axis, M-axis, and Y-axis is reflected on the color reproduction characteristic, respectively.
The dot% data in the K-axis direction is the C-axis, M
It is not reflected in the same manner as the dot% data in each axis direction of the axis and Y axis. That is, in inverse proportion to the change in the value of the dot% data in the K-axis direction, the color reproduction area of the dot% data in the K-axis direction becomes narrow. Therefore, here, the network% data in the K-axis direction is converted into a series of network% such as 0%, 10%, ..., 100%.
A description will be given by fixing the data to data and replacing the CMYK four color space with a set of a series of CMY color spaces corresponding to such a series of halftone dot data.

Regarding the correspondence between the coordinates existing in the series of CMY color spaces and the colorimetric values among the coordinates of the color spaces of the four colors of CMYK, it corresponds to the respective coordinates in the series of CMY color spaces. The calculated colorimetric value is calculated as described later, and the calculated colorimetric value is interpolated between the CMY color spaces.

In the basic lattice setting process (step S2) and the unit lattice setting process (step S3) of the color reproduction characteristic creating method shown in FIG. 7, the basic lattice (the first lattice in the present invention is referred to as follows. C) corresponding to grid points of each example) and unit cell (an example of the second cell according to the present invention)
MY values are extracted from the plurality of CMY values represented by the plurality of paired data acquired in the paired data acquisition process (step S1).

FIG. 10 is a conceptual diagram showing the processing in the basic grid setting step (step S2) and the unit grid setting step (step S3) of the color reproduction characteristic creating method shown in FIG.

For convenience of description, CMY is used here.
A description will be given using a CM plane 900 in which halftone dot data in the Y axis direction of the color space is fixed, the C axis of the CMY color space is the horizontal axis, and the M axis of the CMY color space is the vertical axis.

Further, on the CM plane 900, a basic lattice 910 shown by a solid line in the figure and a broken line in the figure, which are obtained by a basic lattice setting process (step S2) and a unit lattice setting process (step S3) described later. A unit cell 920 indicated by is shown. Furthermore, this CM plane 900
, The grid points 911 indicated by black circles in the figure, the grid points 921 indicated by black squares in the figure, and x points in the figure as points corresponding to the paired data acquired in the data acquisition process (step S1).
Points 931 indicated by marks are shown. Here, a grid point 941 in which none of the grid points 911, 921, and 931 is shown represents a grid point for which no paired data acquired in the data acquisition process (step S1) exists. There is.

As shown in FIG. 10, in the basic grid setting process (step S2) of the color reproduction characteristic creating method shown in FIG.
C such that a group of CMY values corresponding to all grid points are all in the plurality of CMY values represented by the plurality of paired data acquired in the paired data acquisition process (step S1),
A grid on the MY color space is obtained, and such a grid is used as a basic grid 910 to extract a group of CMY values. In the example shown in FIG. 10, the CMY three-color halftone dot data is 0.
Coordinates of grid points 911 indicated by black circles in the figure are extracted, such as%, 20%, 60%, and 100%.

The basic lattice 910 is not determined before the basic lattice setting process (step S2) is executed, and the basic lattice 910 is recognized by executing the basic lattice setting process (step S2). To be done.

In the unit grid setting step (step S3) of the color reproduction characteristic creating method shown in FIG. 7, C among the plurality of CMY values represented by the plurality of paired data acquired in the paired data acquisition step (step S1) is used. CMY values that represent coordinates that are regularly present on each of the axes, the M axis, and the Y axis are determined, and the CMY values that extend through the coordinates in the directions of the C axis, the M axis, and the Y axis in a grid pattern are obtained. A lattice that intersects with each other is regarded as a unit lattice 920, and CMY corresponding to lattice points of the unit lattice 920.
The value is extracted. In the example shown in FIG. 10, the C axis, the M axis, and the Y axis
A grid passing through the coordinates existing in 10% steps on each axis is regarded as a unit grid 920, and grid points 92 shown by black squares in the figure.
The coordinate of 1 is extracted. The coordinates shown on the C-axis, the M-axis, and the Y-axis at every 10% are examples of the regular on-axis coordinates referred to in the present invention.

The unit lattice 920 is not determined before the unit lattice setting process (step S3) is executed, and the unit lattice 920 is recognized by executing the unit lattice setting process (step S3). To be done.

In addition, the profile created in this embodiment associates colorimetric values with all the lattice points of the unit lattice 920 including the basic lattice 910 recognized in this way.

Note that the coordinates of the point 931 indicated by the X mark in FIG. 10 are the basic lattice 910 and the unit described above among the plurality of CMY values represented by the plurality of paired data acquired in the paired data acquisition process (step S1). The CMY values that deviate from all the grid points of each grid 920 are represented, and the handling of the coordinates of the point 931 indicated by the X mark will be described later.

As described above, in the basic lattice setting process (step S2) and the unit lattice setting process (step S3) of the color reproduction characteristic creating method shown in FIG.
0 and unit grid 920, respectively, grid points 911 and 92
A CMY value corresponding to 1 is extracted. Then, in the basic lattice setting step (step S2) and the unit lattice setting step (step S3), each L ^* a ^* b ^* value paired with the extracted CMY value is the CMY extracted by the profile. It is set as the L ^* a ^* b ^* value associated with the value.

Here, when there are a plurality of paired data corresponding to one of the grid points 911 and 921 described above, the average value of a plurality of L ^* a ^* b ^* values in the plurality of paired data. Is used.

Next, in the interpolation process (step S4), among all the lattice points of the unit lattice 920, the profile is associated with the lattice point 941 for which the paired data acquired in the paired data acquisition process (step S1) does not exist. L ^* a ^*
The b ^* value is obtained and set by interpolation based on the L ^* a ^* b ^* value set at the grid point 911 of the basic grid 910. The calculation method of this interpolation will be described later.

FIG. 11 is a conceptual diagram showing the processing in the first correction process (step S5) of the color reproduction characteristic creating method shown in FIG.

In the first correction process (step S5), the paired data acquisition process (step S1) is performed in the cubic area surrounded by the eight lattice points 911 of the basic lattice 910.
Unit cell 920 corresponding to the paired data acquired by
If there is a grid point 921 (hereinafter, this grid point 921 is referred to as a grid point P in the description of FIG. 11), the L ^* a ^* b ^* value represented by the paired data is used to create another grid point. 941
(Hereinafter, in the description of FIG. 11, this grid point 941 is referred to as grid point Q), the L ^* a ^* b ^* value corresponding to the grid point 941 is corrected.

FIG. 11 shows a region 950 surrounded by eight lattice points 911 of the basic lattice 910 and a lattice existing in the region 950 corresponding to the paired data acquired by the paired data acquisition process (step S1). The point P is illustrated. L ^* a ^* b ^* values corresponding to the other lattice point Q indicated by the + sign in the region 950 are set L ^* a ^* b ^* values by interpolation process (step S4), and the grid point Q The L ^* a ^* b ^* values corresponding to are modified.

In correcting this, first, the CM of the lattice point P
The Y value and the CMY value and L ^* a ^* b ^* value of each of the eight lattice points 911 of the basic lattice 910 are used to calculate the same calculation method as the interpolation calculation method in the interpolation step (step S4) (described later). ), L ^* a ^* b for the grid point P
The interpolated value of the ^* value is obtained, and the difference ΔP between the interpolated value and the L ^* a ^* b ^* value of the paired data obtained by the measurement is obtained.
Then, using this ΔP, L ^* a ^* b ^{* of the} lattice point Q is
The correction amount ΔQ with respect to the value is obtained by the following equation (1).

ΔQ = ΔP · d1 / (d0 + d1) (1) Here, d1 indicates the distance from the lattice point Q to the lattice point 911 of the closest basic lattice 910, and d0 indicates the lattice point P.
And the grid point Q.

The correction amount ΔQ thus obtained is
The correction is performed by adding to the L ^* a ^* b ^* value corresponding to the grid point Q.

Incidentally, this first correction process (step S5)
Is not necessarily required in the present invention, but when the processing of the first correction step (step S5) is performed, L ^* based on the measurement set by the unit cell setting step (step S3) as described above is performed ^. effect of a ^* b ^* values, because it is reflected in the interpolated value of the set L ^* a ^* b ^* values by interpolation process (step S4), and it is possible to create a more accurate profile.

In addition, this first correction process (step S
In the explanation of 5), in the case where there is one grid point of the unit grid corresponding to the paired data acquired in the paired data acquisition step (step S1) in the area surrounded by the eight grid points of the basic lattice, L ^* corresponding to other grid points in the region
The example in which the a ^* b ^* values are modified has been explained, but within that area,
When there are a plurality of grid points corresponding to the paired data acquired in the paired data acquisition process (step S1),
For example, as described above, based on each of the plurality of grid points corresponding to the paired data acquired by the paired data acquisition step (step S1) with respect to the L ^* a ^* b ^* value of another grid point in the region. The correction amount ΔQ is calculated for each grid point, and the average value of the calculated plurality of correction amounts ΔQ is averaged,
The correction is performed by adding to the L ^* a ^* b ^* values corresponding to the other grid points in the region.

FIG. 12 is a conceptual diagram showing the processing in the second correction step (step S6) of the color reproduction characteristic creating method shown in FIG.

Among the plurality of CMY values represented by the plurality of paired data acquired in the paired data acquisition process (step S1), there may be CMY values outside the lattice points 921, 941 of the unit lattice 920. . In the second correction process (step S6), when there are CMY values that deviate from the grid points 921 and 941 of the unit grid 920, the L ^* a ^* b ^* value of the paired data having the CMY value is present. Is used to modify each L ^* a ^* b ^* value corresponding to each of the eight grid points 941 surrounding the CMY value.

Here, the grid points 9 of the unit grid 920 are used.
Lattice points 92 surrounding CMY values deviating from 21,941
An example will be described in which the L ^* a ^* b ^* values corresponding to the lattice points 921 of the unit lattice 920 corresponding to the paired data acquired in the paired data acquisition process in 1,941 are not corrected. The second correction process referred to in the invention is that the lattice points 92
The L ^* a ^* b ^* value corresponding to 1 may also be modified.

[0107] Here, for convenience, this point 9
The L ^* a ^* b ^* values corresponding to each of the four grid points 941 surrounding 31 are referred to as P1, P2, P3, and P4, and will be described below in two dimensions.

In FIG. 12, a region 960 surrounded by four lattice points 941 of the unit lattice 920 and a CMY value represented by the paired data existing in the region 960 and acquired by the paired data acquisition process (step S1). Corresponding to, in the figure ×
Points 931 indicated by marks are illustrated. P corresponding to each of the lattice points 941 indicated by + marks surrounding this point 931
1, P2, P3 and P4 are L ^* a ^* b ^* values set by the interpolation process (step S4), and these grid points 9
P1, P2, P3, P4 corresponding to each 41 are modified.

In correcting this, first, the CM at point 931
The Y value and the CMY value and L ^* a ^* b ^* value of each of the four grid points 941 of the unit grid 920 are used to generate a point 93
The interpolated value V of the L ^* a ^* b ^* value for 1 is obtained by the following equation (2). The equation (2) shows the calculation method of the interpolation in the above-mentioned interpolation process (step S4).

V = a0 · P0 + a1 · P1 + a2 · P2 + a3 · P3 (2) where a0 + a1 + a2 + a3 = 1 where a0, a1, a2, and a3 are units with the point 931 in the area 960 shown in FIG. 12 as an intersection. The area of each region when divided into four parallel to the grid lines of the grid 920 (hereinafter, this area is referred to as a weighting coefficient) is shown. Further, here, for the sake of convenience of description, since the description is made in two dimensions, the calculation method of the interpolation based on the four grid points 941 is shown.
Since it is a dimension, in that case, the calculation method of interpolation is based on the eight lattice points 941, and the weighting factor is the volume of each region.

Next, the interpolated value obtained by the above equation (2)
V and L of paired data obtained by measurement ^*a^*b^*Difference from the value
ΔV is required.

The difference ΔV thus obtained is P1, P2, P3, P4 corresponding to each lattice point 941.
The correction is made by adding to.

The second correction process (step S6)
Similarly to the first correction process (step S5), the second correction process (step S6) is not always necessary in the present invention, but if the process of the second correction process (step S6) is performed, the pair data acquisition process (step The L ^* a ^* b ^* value of the paired data having a CMY value out of the grid point of the paired data acquired in S1) is set by the interpolation process (step S4) for the grid point surrounding the CMY value. L ^* a ^*
Since it is reflected in the b ^* value, it is possible to create a desirable profile with higher accuracy in which all the paired data acquired in the paired data acquisition process are reflected.

In addition, this second correction process (step S
In the description of 6), in the area surrounded by the eight lattice points of the unit cell, there is a point outside the lattice point of the unit cell, which corresponds to the paired data acquired in the pair data acquisition step (step S1). In this case, an example in which each L ^* a ^* b ^* value corresponding to each of the eight lattice points surrounding the point is corrected has been described. However, the L ^* a ^* b ^* value is obtained in the area by the pair data acquisition process (step S1). When there are a plurality of points corresponding to the paired data and deviating from the lattice points of the unit grid, for example, as described above, the points correspond to the paired data acquired by the paired data acquisition step (step S1), L ^* a ^* corresponding to each of a plurality of points deviating from the grid point of the unit grid
The interpolated value V of the b ^* value is obtained for each point, and the difference ΔV between the interpolated value V obtained and the L ^* a ^* b ^* value of the paired data obtained by the measurement is obtained for each point, The average value obtained by averaging the differences .DELTA.V is added to each L ^* a ^* b ^* value corresponding to each of the eight grid points surrounding the plurality of points, so that the correction is performed.

In addition, this second correction process (step S
6), the obtained difference ΔV is the grid point 941.
The example in which the correction is performed by adding the L ^* a ^* b ^* values corresponding to the respective values has been described.
In the correction process of, the obtained difference ΔV is added only to the L ^* a ^* b ^* value corresponding to the lattice point 941 having the maximum corresponding weighting coefficient, and the obtained difference ΔV is associated with the corresponding weight. Each remaining grid point 94 except the grid point 941 having the smallest coefficient
And it is added to the L ^* a ^* b ^* values corresponding to 1, the difference ΔV obtained is the corresponding weighting factor is added to the L ^* a ^* b ^* values corresponding to the lattice points 941 of a predetermined value or more The correction may be performed by doing so.

As described above, according to the color reproduction characteristic creating method, the color reproduction characteristic creating apparatus, and the color reproduction characteristic creating program for operating the computer as such a color reproduction characteristic creating apparatus according to the present embodiment, the halftone dot By measuring the color chart based on the CMYK four-color halftone dot data in which R is changed at an arbitrary ratio, the CMYK values of the CMYK four-color color space and the L ^* a ^* on the L ^* a ^* b ^* color space are measured ^. A plurality of paired data representing a pair with a b ^* value is acquired, and any CM of the paired data is acquired.
The basic lattice and the unit lattice are recognized based on the YK value, and the CMYK values corresponding to the lattice points of the thus-recognized basic lattice and unit lattice are acquired by the pair data acquisition process (step S1). It is extracted from a plurality of CMYK values represented by a plurality of paired data. Further, in the interpolation process (step S4), CMY corresponding to the grid point
The L ^* a ^* b ^* value that the profile corresponds to the grid point for which there is no paired data corresponding to the K value is obtained by interpolation based on the L ^* a ^* b ^* value set at the grid point of the basic grid. Since it is set based on, it is not premised that a predetermined grid is formed from a plurality of acquired paired data, such as a color chart in which color patches containing colors that the user considers important are arranged. By using an arbitrary color chart in which arbitrary color patches are arranged, it is possible to create a profile in which the colors of the arbitrary color patches are accurately reflected.

The profile thus obtained is installed in the personal computer 50 constituting the printing and proof image creation system shown in FIG. 1, and the CMYK image data for printing is used for the printer CMYK. Image data. The printer 60 prints out an image based on the CMYK image data for the printer, thereby creating a proof image in which the colors of the printed image are reproduced.

In the description of the above embodiment, one basic lattice was found in the basic setting process of the color reproduction characteristic creating method shown in FIG. 7, but in the first lattice setting process of the present invention, Multiple basic lattice candidates may be found. Hereinafter, various aspects of a method of dealing with a case where a plurality of basic lattice candidates are found in the first lattice setting process according to the present invention will be described. Note that, in the following, the elements of the above-described embodiment will be used as they are, and description will be omitted.

First, when a plurality of basic lattice candidates are found in the basic lattice setting process of the color reproduction characteristic creating method shown in FIG. 7, one basic lattice is selected from the plurality of basic lattice candidates, The corresponding method set as the basic grid will be described with reference to FIGS. 13 and 14.

13 and 14 are diagrams showing an example of a plurality of basic lattice candidates found in the basic lattice setting step (step S2) of the color reproduction characteristic creating method shown in FIG.

For convenience of explanation, CMY is used here.
A description will be given using a C-M plane 400 in which halftone dot data in the Y axis direction of the color space is fixed, the C axis of the CMY color space is the horizontal axis, and the M axis of the CMY color space is the vertical axis.

In FIG. 13, the basic lattice setting process (step S2) of the color reproduction characteristic creating method shown in FIG. 7 is executed, whereby the basic lattice 410 shown by the solid line in the figure is selected as the first candidate of the basic lattice. A recognized example is shown in FIG.
The points corresponding to the paired data acquired by the data acquisition process (step S1) shown in FIG.
Coordinates of grid points 411 indicated by black circles in the figure are extracted.

Further, in FIG. 14, the basic grid setting process (step S2) of the color reproduction characteristic creating method shown in FIG. 7 is executed, so that the basic grid shown by the solid line in FIG. An example in which 510 is recognized is shown, and as the points corresponding to the paired data acquired in the data acquisition process (step S1) shown in FIG. 7, CMY three-color halftone% data is 0%, 40%, and 80%. , 100%, the coordinates of the grid point 511 indicated by a black circle in the figure are extracted.

When one basic lattice is selected from a plurality of basic lattice candidates, the number of lattices of each of the plurality of basic lattices is compared, and the one having the largest number of lattices is selected. Here, if the number of basic lattices to be compared is the same, the one with a narrower lattice spacing on the highlight side is selected.

Here, in general, the "highlight side" is C
Area with small CMY values in MY color space, or RGB
It refers to a region with a large RGB value in the color space. On such a highlight side, CMY values or RGB
Since the color changes greatly even if the value slightly changes, it is possible to obtain a more accurate color reproduction characteristic by creating the color reproduction characteristic based on the basic lattice having a narrow lattice spacing on the highlight side.

In the examples shown in FIGS. 13 and 14, the number of the basic lattices 410 shown in FIG. 13 and the basic lattice 5 shown in FIG.
Since the number of grids of 10 is the same, the basic grid is selected based on the grid spacing on the highlight side.

In the examples shown in FIGS. 13 and 14, the lattice spacing of the basic lattice 410 shown in FIG. 13 is 0%, 20%, 60%,
In contrast to 100%, the basic lattice 51 shown in FIG.
The grid spacing of 0 is 0%, 40%, 80%, and 100%. Since the grid spacing on the highlight side of the basic grid 410 shown in FIG. 13 is narrower, this basic grid 410 is selected and set. It

Next, when a plurality of basic grid candidates are found in the basic grid setting process of the color reproduction characteristic creating method shown in FIG. 7, all of the plurality of basic grid candidates are set as basic grids. The method will be described with reference to FIGS.

15 and 16 are diagrams showing another example of a plurality of basic lattice candidates found in the basic lattice setting step (step S2) of the color reproduction characteristic creating method shown in FIG.

For convenience of explanation, CMY is used here.
A description will be given using a C-M plane 600 in which halftone dot data in the Y axis direction of the color space is fixed, the C axis of the CMY color space is the horizontal axis, and the M axis of the CMY color space is the vertical axis.

In FIG. 15, the basic grid setting step (step S2) of the color reproduction characteristic creating method shown in FIG. 7 is executed to show another example of the first candidate of the basic grid, which is shown by a solid line in the figure. An example in which the basic lattice 610 is recognized is shown. As points corresponding to the paired data acquired in the data acquisition process (step S1) shown in FIG. 7, CMY three-color halftone dot% data is 0%, 10%, 20%, 40%, 70%
The coordinates of the grid point 611 indicated by black circles in the figure are extracted. Further, the unit cell 620 shown by the broken line in the figure is recognized by executing the unit cell setting step (step S3) shown in FIG. 7, and the paired data acquired by the data acquisition step (step S1) shown in FIG. As the points corresponding to, the coordinates of grid points 621 indicated by black squares in the figure, which are present at 10% intervals on each of the C-axis, M-axis, and Y-axis, are extracted.

In FIG. 16, the basic grid setting process (step S2) of the color reproduction characteristic creating method shown in FIG. An example in which the basic lattice 710 shown in is recognized is shown, and the data acquisition process (step S
As points corresponding to the paired data acquired by 1),
CMY 3 color halftone dot data is 0%, 20%, 70%, 10
Coordinates of the grid point 711 indicated by a black circle in the figure, which is 0%, are extracted. Similar to the example shown in FIG. 15, FIG. 16 also shows a unit cell 620 indicated by a broken line in the figure and a lattice point 621 indicated by a black square in the figure.

Note that, in FIGS. 15 and 16, grid points in which neither black circles nor black squares are shown are grid points for which there is no paired data acquired in the data acquisition process (step S1).

When the L ^* a ^* b ^* values that the profile corresponds to such grid points for which no paired data exists are obtained and set by the interpolation process (step S4) shown in FIG. 7, they are set. Of the basic lattices,
The above-described interpolation calculation is executed based on the lattice point of the basic lattice having the smaller volume of the cubic region surrounded by the eight lattice points of the basic lattice to which the lattice point to be interpolated belongs.

In the examples shown in FIGS. 15 and 16, the grid point 641_1 is shown as a + mark in the figures as a first example of the grid point where no paired data exists. Here, this grid point 641_
As a volume of a cubic area surrounded by eight lattice points of the basic lattice to which 1 belongs, a volume of a cubic area surrounded by eight lattice points of the basic lattice 711 shown in FIG.
Since the cubic area surrounded by the eight lattice points of the basic lattice 611 shown in FIG. 15 has a smaller volume, the basic lattice 61 shown in FIG.
The above-described interpolation calculation is executed based on the eight grid points of 1.

The second grid point for which no paired data exists
As an example, the grid point 641_2 is indicated by a + mark in the figure.
In this case, the volume of the cubic area surrounded by the eight lattice points of the basic lattice 611 shown in FIG. 15 is defined as the volume of the cubic region surrounded by the eight lattice points of the basic lattice to which this lattice point 641_2 belongs. 16 has a smaller volume than the cubic area surrounded by the eight lattice points of the basic lattice 711 shown in FIG. 16, the eight lattices of the basic lattice 711 shown in FIG. Based on the points, the interpolation calculation described above is performed.

In the corresponding method described with reference to FIGS. 15 and 16, of the plurality of set basic lattices, the lattice points to be interpolated are surrounded by eight lattice points of the basic lattice. Although an example in which the interpolation calculation is executed based on the basic lattice with the smaller volume of the cubic area is shown, in the present invention, for each of the plurality of basic lattices set for the lattice point where no pair data exists. A corresponding method may be adopted in which the interpolated value is calculated based on the calculated interpolated value and the average value of the calculated interpolated values is used as the interpolated value of the grid point.

In the description of this embodiment, as an example of the plurality of primary colors in the present invention, C (C
yan: cyan), M (magenta: magenta),
Although an example of three colors of Y (Yellow: yellow) is shown,
The plurality of primary colors referred to in the present invention are R, which are three primary colors of additive color mixture.
(Red: red), G (green: green), B (blue)
e: blue), or the combination of any primary colors is not limited to three colors.

In this embodiment, the CMYK color space and L
^The present invention relates to a method of creating a profile that handles conversion between the ^* a ^* b ^* color space, but the present invention is not limited to this, and the RGB color space and the XYZ color space, or the CMYK color space.
It can also be applied when creating a profile that defines the relationship between the color space or RGB color space and the L ^* a ^* b ^* color space or the like.

Further, in the description of the present embodiment, as an example of the coordinate on the regular axis referred to in the present invention, the coordinate in 10% increments on each of the C-axis, the M-axis and the Y-axis is shown. In the second grid setting process according to the invention, the coordinate values of the on-axis coordinates are, for example, 5%, 10%, 20%, 40%, ... The unit cell may be obtained, or the unit cell may be obtained simply by using on-axis coordinates that exist on the axis without regularity.

[0141]

As described above, according to the present invention,
A color reproduction characteristic creating method, a color reproduction characteristic creating apparatus capable of creating a color reproduction characteristic using an arbitrary color chart,
And a color reproduction characteristic creating program for operating a computer as such a color reproduction characteristic creating apparatus.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a printing and proof image creation system that employs a profile created by the present invention.

FIG. 2 is an external perspective view of a spectrocolorimeter shown by a block in FIG. 1 and a personal computer that constitutes an embodiment of a color reproduction characteristic creating apparatus of the present invention.

FIG. 3 is a hardware configuration diagram of the personal computer shown in FIG.

FIG. 4 is a conceptual diagram of a print profile.

FIG. 5 is a conceptual diagram of a printer profile.

FIG. 6 is a diagram showing a profile in which a print profile and a printer profile are combined.

FIG. 7 is a flowchart showing an embodiment of a color reproduction characteristic creating method of the present invention.

FIG. 8 is a diagram showing an embodiment of a color reproduction characteristic creating program of the present invention.

FIG. 9 is a functional block diagram showing an embodiment of a color reproduction characteristic creating device of the present invention.

10 is a conceptual diagram showing processing in a basic lattice setting process (step S2) and a unit lattice setting process (step S3) of the color reproduction characteristic creating method shown in FIG. 7.

11 is a conceptual diagram showing a process in a first correction process (step S5) of the color reproduction characteristic creating method shown in FIG.

FIG. 12 is a conceptual diagram showing a process in a second correction step (step S6) of the color reproduction characteristic creating method shown in FIG. 7.

13 is a diagram showing an example of a first candidate of a basic lattice found in a basic lattice setting process (step S2) of the color reproduction characteristic creating method shown in FIG.

14 is a diagram showing an example of a second candidate of the basic lattice found in the basic lattice setting step (step S2) of the color reproduction characteristic creating method shown in FIG.

15 is a diagram showing another example of the first candidate of the basic lattice found in the basic lattice setting process (step S2) of the color reproduction characteristic creating method shown in FIG.

16 is a diagram showing another example of the second candidate of the basic lattice found in the basic lattice setting step (step S2) of the color reproduction characteristic creating method shown in FIG.

[Explanation of symbols]

10 Color Scanner 11 Original Image 20 Workstation 30 Film Printer 40 Printing Machine 41 Printed Image 50 Personal Computer 60 Printer 61 Proof Image 70 Spectral Colorimeter 80 Personal Computer 81 Main Unit 81a FD Loading Port 81b CD-ROM Loading Port 811 CPU 812 Main memory 813 Hard disk device 814 FD drive 815 CD-ROM drive 816 I / O interface 82 Image display device 82a Display screen 83 Keyboard 84 Mouse 85 Bus 90 Color chart 91 Cable 100 FD 110 CD-ROM 210 Color reproduction characteristic creation program 300 colors Reproduction characteristics creating device 211, 311 Pair data acquisition unit 212, 312 Basic lattice setting unit 213, 313 Unit lattice setting unit 214, 314 Interpolation unit 2 5,315 The first correcting unit 216, 316, the second correction unit 900,400,600 C-M plane 910,410,510,610,710 primitive lattice 911,921,941,411,511,611,6
21,641_1, 641_2, 711 Lattice points 920, 620 Unit lattice 931 Points 950, 960 Area

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2C262 AB11 BA01 BA09 BC15 BC19                 5B057 AA11 BA02 CA01 CA08 CA12                       CA16 CB01 CB08 CB12 CB16                       CC01 CE17 CE18 CH07 CH08                 5C077 LL11 MM27 MP08 PP33 PP36                       PP37 PQ12 PQ23                 5C079 HB03 HB08 HB11 LB02 MA05                       MA10 MA11 NA03 NA29 PA02                       PA03

Claims (5)

[Claims] 1. A device-dependent color in a device that mediates between image data representing an image in coordinates of a device-dependent color space that defines a color and having primary color coordinate axes corresponding to each of a plurality of primary colors. In a color reproduction characteristic creating method for creating a color reproduction characteristic that represents a correspondence between space coordinates and a device-independent colorimetric value that represents the color of the image, each of the coordinates of the device-dependent color space and the colorimetric value A pair data acquisition step of acquiring a plurality of pair data representing a pair of, and among the plurality of coordinates represented by the plurality of pair data acquired in the pair data acquisition step, in the direction of the primary color coordinate axes of each of the plurality of primary colors. A group of coordinates corresponding to all the lattice points of the first lattice extending in a lattice shape and intersecting each other is extracted, and each colorimetric value forming the pair is calculated with respect to each of the coordinates of the group. The group A first grid setting step for setting colorimetric values to be associated with the respective coordinates; and on each axis existing on the primary color coordinate axis among the plurality of coordinates represented by the plurality of paired data acquired in the paired data acquisition step. A plurality of pairs of data having a grid line passing through the coordinates, the coordinates corresponding to the grid points of the second grid extending in the grid shape in the directions of the primary color coordinate axes of the plurality of primary colors and intersecting each other are represented by the plurality of paired data. A second grid setting step of extracting from the coordinates, and setting each colorimetric value forming the pair with respect to the extracted coordinates as a colorimetric value associated with the extracted coordinates by the color reproduction characteristic; Of the coordinates corresponding to the grid points of the grid, the colorimetric values associated with the color reproduction characteristics with respect to the coordinates excluding the plurality of coordinates represented by the plurality of paired data acquired in the paired data acquisition process are Set in the grid setting process A color reproduction characteristic creating method, which comprises: an interpolation process of obtaining and setting the colorimetric value based on the obtained colorimetric value. 2. A first correction process for correcting the colorimetric value set in the interpolation process based on the colorimetric value set in the second grid setting process. 1. The method for creating color reproduction characteristics described in 1. 3. Corresponding to a grid point of the second grid surrounding coordinates outside the grid point of the second grid among the plurality of coordinates represented by the plurality of pair data acquired in the pair data acquisition process. A second correction step of correcting the colorimetric value set for the coordinate in the interpolation step based on the colorimetric value forming the pair for the coordinate deviating from the grid point of the second grid. The method for creating a color reproduction characteristic according to claim 1, further comprising: 4. A device-dependent color in a device that mediates between image data representing an image in coordinates of a device-dependent color space that defines a color and having primary color coordinate axes corresponding to each of a plurality of primary colors. In a color reproduction characteristic creating device that creates color reproduction characteristics that represent correspondence between space coordinates and device-independent colorimetric values that represent the color of the image, respectively, the device-dependent color space coordinates and the colorimetric values are provided. A pair data acquisition unit that acquires a plurality of pair data representing a pair of, and among the plurality of coordinates represented by the plurality of pair data acquired by the pair data acquisition unit, in the direction of the primary color coordinate axes of each of the plurality of primary colors. A group of coordinates corresponding to all the lattice points of the first lattice extending in a lattice shape and intersecting each other is extracted, and each colorimetric value forming the pair is calculated with respect to each of the coordinates of the group. The group of seats A first grid setting unit which is set as a colorimetric value associated with each of the coordinates; and on-axis coordinates existing on the primary color coordinate axes among a plurality of coordinates represented by the plurality of pair data acquired by the pair data acquisition unit. A plurality of coordinates represented by the plurality of paired data, the coordinates corresponding to the grid points of the second grid extending in a grid shape in the direction of the primary color coordinate axes of the plurality of primary colors and intersecting each other. A second grid setting unit that sets each colorimetric value that forms a pair with respect to the extracted coordinates as a colorimetric value associated with the extracted coordinates by the color reproduction characteristics; Of the coordinates corresponding to the grid points of the grid, the colorimetric values associated with the color reproduction characteristics with respect to the coordinates other than the plurality of coordinates represented by the plurality of paired data acquired by the paired data acquisition unit are set to the first grid. Based on the colorimetric value set in the setting section An apparatus for producing color reproduction characteristics, comprising: 5. An image processing system, which is executed in a computer, for displaying the image in the coordinates of a device-dependent color space that defines a color and has primary color coordinate axes corresponding to each of a plurality of primary colors. Reproduction characteristic creation device that operates as a color reproduction characteristic creation device that creates a color reproduction characteristic that represents a correspondence between coordinates of the device-dependent color space and a device-independent color measurement value that represents the color of the image It is a program, each pair data acquisition unit for acquiring a plurality of pair data representing a pair of coordinates of the device-dependent color space and the colorimetric value, a plurality of pairs acquired by the pair data acquisition unit From a plurality of coordinates represented by the data, a group of coordinates corresponding to all grid points of the first grid extending in a grid shape in the directions of the primary color coordinate axes of the plurality of primary colors and intersecting each other are extracted. A pair of colorimetric values forming a pair for each of the coordinates of the group as a colorimetric value associated with each of the coordinates of the group of color reproduction characteristics; Among the plurality of coordinates represented by the plurality of paired data acquired by the data acquisition unit, there is a grid line that passes through the on-axis coordinates existing on the primary color coordinate axes, and the grid shape is formed in the direction of the primary color coordinate axes of each of the multiple primary colors. Coordinates corresponding to the grid points of the second grid extending to and intersecting each other are extracted from a plurality of coordinates represented by the plurality of pair data, and each colorimetric value forming the pair with respect to the extracted coordinates, A second grid setting unit that sets the color reproduction characteristic as a colorimetric value associated with the extracted coordinates; and a plurality of coordinates acquired by the paired data acquisition unit among the coordinates corresponding to the grid points of the second grid. Zodiac excluding multiple coordinates represented by the paired data of A color reproducibility characteristic having a colorimetric value associated with the target by the color reproducibility characteristic by interpolation based on the colorimetric value set by the first grid setting section. Creation program.