JP2001229367A - Method and device for generating color conversion definition and storage medium for color conversion definition generation program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To generate a color conversion definition which has a high precision up to the area boundary of a color reproducing area on the basis of pairs of known points having large numbers of degree of freedom by a method which is highly useful for various devices. SOLUTION: The color conversion definition is generated through an approximation stage (S101) where a prescribed number of lattice points are set and positions of lattice corresponding points corresponding to them respectively are calculated by linear approximation on the basis of plural prepared pairs of known points, a first correction stage (S103) where positions of lattice corresponding points are so corrected that a coordinate conversion relation corresponding to a pair of known points selectively acquired from plural pairs of known points may be reproduced, and a second correction stage (S104) where positions of lattice corresponding points corresponding to lattice points in a correction area are corrected by an extent of correction according to the extent of position correction in the first correction stage.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a set of grid point pairs consisting of a set of grid points in a first color space and corresponding grid points in a second color space. A color conversion definition creating method for creating a color conversion definition, a color conversion definition creating device, and a color stored with a color conversion definition creating program incorporated in a computer system to operate the computer system as the color conversion definition creating device The present invention relates to a conversion definition creating program storage medium.

[0002]

2. Description of the Related Art For example, a color scanner for reading a recorded image to obtain image data, a DSC (digital still camera) for forming an image of a subject on a solid-state image sensor and reading the image to obtain image data, and the like. Various types of input devices for inputting an image and obtaining image data are known. In these input devices, the image data is represented by data in a fixed range such as 0 to 255 for each of three colors, for example, R (red), G (green), and B (blue). There is naturally a limit to the colors that can be represented by numerical values within the fixed range for each of the B3 colors, and even if the original image has a very rich expression, it is necessary to use an input device to convert the image data into image data. After conversion, the image represented by the image data is limited to the colors in the color expression area represented by the cube or the rectangular parallelepiped in the R, G, and B color spaces.

[0003] Further, as for an output device for outputting an image based on image data, for example, a photographic printer, an electrophotographic printer for recording an image on a photographic paper by exposing the photographic paper with a laser beam and developing the photographic paper. Printers that record images on paper in a method such as the inkjet printing method or inkjet printing method, printing machines that create large quantities of printed matter by turning rotary presses,
CR that displays an image on a display screen based on image data
Various types of output devices such as an image display device such as a T display and a plasma display are known.
As for these output devices, similar to the above-described input devices, there are color expression regions corresponding to the respective output devices.
That is, the output device may be, for example, image data expressing R, G, and B colors, C (cyan), M (magenta), and Y.
Various colors can be represented based on image data representing four colors of (yellow) and K (black). The colors that can be represented are output device color spaces (for example, RGB space,
It is limited to a color expression region represented by a cube or a rectangular parallelepiped in a CMYK space or the like (for example, a color expression region represented by a numerical value in the range of 0 to 255 for each of R, G, and B).

[0004] Further, for example, even if there is certain image data (eg, image data representing (R, G, B) = (50, 100, 200)), the color of an image obtained based on the image data is output. Depends on device type. This point is the same between the input device and the output device, and (R, G, B) obtained with a certain input device = (5
0, 100, 200) using the image data as it is,
Even when an image is output from an output device, the color of the image input from the input device and the color of the image output from the output device generally do not match. Therefore, when an image is read by a certain input device to obtain image data, and based on the image data, when an original image is to be reproduced by a certain output device, the image data obtained by the input device is directly output to the output device. Rather than sending, it is necessary to convert the image data between them. Here, conversion is performed focusing on the color of the image, and this conversion of image data is referred to as color conversion. Also, an LUT (look-up table) or the like that defines the relationship between the image data before and after the color conversion is called a color conversion definition (color profile).
Creating the color conversion definition (color profile) is called profiling. In other words, this color conversion definition defines a coordinate conversion between two color spaces.

Further, as described above, the color expression area differs depending on each device, and even though the image data is numerically the same, the colors expressed in each device are different from each other. It is desired to construct a device-independent system in which an input device and an output device are interchangeable by mutually connecting a device and an output device. In such a device-independent system, when performing color conversion between devices, a device-independent common color space (Device In) is used.
dependent data space), for example, L ^* a ^*
b ^{* A} color conversion in which an image data in a color space dependent on an input device obtained by an input device is converted to image data in a common color space, and image data in the common color space, with a color space or the like in between. Is converted to image data in a color space depending on an output device. In this device-independent system, a color profile defining color conversion between a color space dependent on an input device and a common color space, and a color profile defining a color space dependent on an output device and a common color space. A color profile that defines the color conversion is created.

[0006] A color conversion definition (color profile) is generally created as a set of point pairs consisting of a set of points in one of two color spaces and a point in the other color space. Table 1 below shows an example of a color conversion definition created as a set of point pairs.

[0007]

[Table 1]

The color conversion definition shown in Table 1 is R
It defines color conversion between the GB color space and the L ^* a ^* b ^* color space. In the left column of Table 1, points in the RGB color space are indicated by coordinate values, and in the right column, ^Indicates a point in the L ^* a ^* b ^* color space as a coordinate value. Points shown in the same column in the left column and the right column correspond to each other. The points shown in the left column of Table 1 are the intersections of the grid lines that are orthogonal to each other in the RGB color space, and such intersections are referred to as grid points.
On the other hand, the points shown in the right column of Table 1 are points randomly distributed in the L ^* a ^* b ^* color space corresponding to the grid points in the RGB color space, and are referred to as grid corresponding points.

As shown in Table 1, practical color conversion definitions include grid points in one of two color spaces between which color conversion is defined, and grid points in the other color space. Need to be created as a set of grid point pairs consisting of a set of grid corresponding points. The manner in which color conversion is performed according to the color conversion definition created in this way will be described below.

FIG. 1 is a conceptual diagram illustrating color conversion according to the color conversion definition.

In this conceptual diagram, a grid point 1 in an RGB color space is shown.
And a grid corresponding point 2 in the L ^* a ^* b ^* color space are shown,
Also shown is a grid line 3 in the RGB color space and a curve 4 in the L ^* a ^* b ^* color space corresponding to the grid line. The correspondence between the grid point 1 and the grid corresponding point 2 and the correspondence between the grid straight line 3 and the curve 4 can be derived from the color conversion definition.

The image data to be subjected to color conversion is grid point 1
Is converted to image data representing a grid corresponding point 2 corresponding to the grid point 1, and if the image data to be subjected to color conversion is image data representing the grid corresponding point 2, Is naturally converted to image data representing the grid point 1 corresponding to the grid corresponding point 2.

The image data to be subjected to the color conversion is RGB.
In the case of image data representing a point 5 different from the grid point 1 in the color space, the volume is determined based on the grid points 1a around the point 5 and the grid corresponding points 2a corresponding to the respective grid points 1a. An interpolation operation, a triangular pyramid interpolation operation, a polynomial approximation calculation, and the like are performed, and L ^* a ^* b corresponding to point 5 in the RGB color space is obtained.
^* The position of point 6 in the color space is calculated, and the image data representing point 5 is converted to image data representing point 6. In the following, the position of a point in the color space and the point itself may be expressed as “calculate a point” without distinction.

Conversely, image data to be subjected to color conversion is
In the case of image data representing the point 6 in the L ^* a ^* b ^* color space, a convergence operation by the Newton method or another convergence operation is used, and the calculation result such as the above volume interpolation operation is converted to the point 6. The point 5 in the RGB color space is calculated as
The image data representing point 6 is converted to image data representing point 5. However, actually, prior to the color conversion for each image data, grid points in the L ^* a ^* b ^* color space are prepared, and grid corresponding points in the RGB color space are calculated by convergence calculation by the Newton method or the like. As a result, an inverse conversion definition that defines the color conversion from the L ^* a ^* b ^* color space to the RGB color space is created in advance, and the color conversion is performed by volume interpolation calculation or the like based on the inverse conversion definition. It is often said.

As profiling for creating the above-described color conversion definition (color profile), the following various profilings have been proposed. In general profiling, a known point in a first color space (for example, an RGB color space) is obtained by reading an image of a color chart with an input device, outputting the image with an output device, or measuring a color with a colorimeter. And a known point pair corresponding to the known point and a known point pair in a second color space (for example, an L ^* a ^* b ^* color space) are prepared. A conversion definition is created. However, in the following description, data representing a known point pair and a known point pair may be used without distinction. In addition, for convenience of description, the following description is given on the assumption that a color conversion definition that defines color conversion between the RGB color space and the L ^* a ^* b ^* color space is created.

In the first profiling, a grid point pair as shown in Table 1 is obtained as a known point pair, and a color conversion definition is created as a set of the obtained grid point pairs.
That is, it is necessary to prepare a color chart created so that the grid point pair itself can be obtained by measurement or the like.

In the second profiling, for example, a color conversion definition is created based on a set of known point pairs as shown in Table 2 below.

[0018]

[Table 2]

In the left column of Table 2, coordinates of a known point in the RGB color space are shown, and in the right column, L ^* corresponding to the known point is shown ^.
The coordinates of known corresponding points in the a ^* b ^* color space are shown. In both the known points and the known corresponding points shown in Table 2, the distribution of the points is an irregular distribution having no regularity like the above-described grid points.

In the second profiling, Table 2 shows
A color conversion definition is created based on a set of such known point pairs.
That said, this second profiling is
A known point pair as shown in FIG.^*a^*b^*
A grid point in some third color space different from the color space
Need to respond. And the third color sky
Intermediately, the above-described volume interpolation calculation and the like are performed, and R
GB color space and L^*a^*b ^*Define color conversion to and from color space
A set of grid point pairs is calculated, and a color conversion definition is created.
You.

In the third profiling, the correspondence between the space coordinates in the RGB color space and the space coordinates in the L ^* a ^* b ^* color space is approximated by, for example, a first-order polynomial as shown below.

[0022]

(Equation 1)

Then, the elements a11,
a12,..., a33, a34 are calculated based on a set of known point pairs as shown in Table 2 to obtain RGB.
The correspondence between the space coordinates of the color space and the space coordinates of the L ^* a ^* b ^* color space is calculated. Then, the elements a11, a12,
.., A33, a34 are calculated according to the coefficient matrix calculated, and a color conversion definition is created. RG
Polynomials that approximate the correspondence between the space coordinates of the B color space and the space coordinates of the L ^* a ^* b ^* color space include R ² , RG,
Polynomials including higher-order terms such as B ³ , R ² G, etc. are also conceivable.

The fourth profiling is based on the premise that a physical model represented by the following equation, which represents the physical relationship between the light emission luminance of the CRT and the spatial coordinates of the RGB color space, is established.

[0025]

(Equation 2)

Then, using the following equation derived from such a model and a set of known point pairs as shown in Table 2 above, the spatial coordinates of the RGB color space and L
The corresponding relationship with the space coordinates of the ^* a ^* b ^* color space is calculated.

[0027]

(Equation 3)

The elements a11, a12,
, A32, a33 are calculated, so that RGB
The correspondence between the space coordinates of the color space and the space coordinates of the L ^* a ^* b ^* color space is calculated. Then, the elements a11, a12,
.., A32, a33 are calculated according to the coefficient matrix for which the color matrix is calculated, and a color conversion definition is created.

[0029]

In preparing a known point pair for creating a profile, input and output of a color chart and color measurement are performed. Examples of the color chart include an IT8 chart and a Macbeth chart. It is desirable to be able to use an existing chart such as a chart in which patch rules are determined in advance, or a chart in which patches of important colors are focused. However, in the first profiling and the second profiling described above, in many cases, existing charts and the like cannot be used.

The known point pairs obtained by inputting / outputting a color chart and colorimetry are represented by spatial coordinates of an RGB color space and L ^*.
Since it represents the most accurate correspondence with the space coordinates of the a ^* b ^* color space, it is desirable to create a color conversion definition that reproduces this correspondence. However, in the third profiling described above, since the color conversion definition is created by approximation, there is a strong possibility that the created color conversion definition does not reproduce the exact correspondence represented by the pair of known points. On the other hand, in order to better reproduce the exact correspondence represented by the pair of known points, RGB
When a polynomial including a higher-order term is used as a polynomial that approximates the correspondence between the space coordinates of the color space and the space coordinates of the L ^* a ^* b ^* color space, the color conversion definition near the region boundary of the color expression region is obtained. There is a high possibility that a failure will occur in the correspondence represented by.

Further, it is desirable that profiling has high versatility for various devices. However, the above-described fourth profiling is profiling that can be applied only to a device for which a physical model is established. Little versatility.

As described above, all of the conventional profiling has advantages and disadvantages.

In view of the above circumstances, the present invention is a method for creating a color conversion definition that has a high degree of freedom of a known point pair as a premise for creating a color conversion definition and has high versatility for various devices.
Furthermore, a color conversion definition creating method capable of creating a high-precision color conversion definition up to an area boundary of a color expression area, a color conversion definition creating apparatus that executes such a color conversion definition creating method,
It is another object of the present invention to provide a color conversion definition creating program storage medium storing a color conversion definition creating program that causes a computer system to operate as such a color conversion definition creating device.

[0034]

According to a first aspect of the present invention, there is provided a color conversion definition creating apparatus, comprising: a plurality of grid lines intersecting in a grid in a predetermined first color space; Of a first color space and a second color space, each of which is a set of grid point pairs each including a set of grid points corresponding to grid points corresponding to grid points in a predetermined second color space. Each of the color conversion definitions that define the coordinate conversion between the two consists of a set of a known point in the first color space and a known corresponding point in the second color space corresponding to the known point. A method for creating a color conversion definition based on a plurality of pairs of known points, wherein a position of a predetermined number of grid points in a first color space is set, and a grid correspondence corresponding to each of the set grid points is set. The positions of the points in the second color space are represented by their grids in the second color space. The grid corresponding points corresponding to the grid points linearly arranged in the first color space are such that the distribution of the corresponding points approximates the distribution of the known corresponding points constituting each of the plurality of known point pairs. An approximation process of calculating under the condition that they are linearly arranged in the second color space, and a known point pair is selectively acquired from the plurality of known point pairs, and the position is set in the approximation process. One of the predetermined number of grid corresponding points corresponding to each of the predetermined number of grid points, one corresponding to each of one or more grid points including the closest grid point to the known point constituting the acquired known point pair The position of the above grid corresponding point in the second color space is corrected so that the coordinate conversion between the known point and the known corresponding point forming the acquired known point pair is reproduced by the color conversion definition. 1 correction process and known information obtained in the 1st correction process In the first correction process, of the grid corresponding points corresponding to the grid points existing inside the correction area obtained by the predetermined algorithm in the first color space so that only one known point constituting the pair exists therein, A second correction process of correcting the positions in the second color space of the grid corresponding points other than the position-corrected grid corresponding points by a correction amount according to the correction amount of the position corrected grid corresponding points. It is characterized in that a color conversion definition is created through the process.

This is a method for creating a color conversion definition which has a high degree of freedom of a known point pair as a premise for creating a color conversion definition and has high versatility for various devices. Possible color conversion definition creation methods include:
A method of creating a color conversion definition as a set of a known point pair and a grid point pair calculated based on the known point pair can be considered. However, it is necessary to calculate a large number of lattice point pairs such as the cube of the number of known point pairs or the fourth power, and it is difficult to store such a large number of lattice point pairs. When the acquisition of the known point pair and the calculation of the lattice point pair are alternately repeated, the known point pair acquired later contributes to the calculation of the lattice point pair only in a narrow area in the color space. I do.

On the other hand, in the color conversion definition creating method of the present invention, an approximate color conversion definition is once created in the approximation process.
Since the approximate color conversion definition is corrected according to the known point pair in the first correction process and the second correction process, the degree of freedom of the known point pair is high. In the approximation process, a predetermined number of grid points are set, so that the number of grid points can be suppressed to a desired number. In this approximation process, so-called first-order approximation is used, so that the distribution range of known points is , The breakdown of the color conversion definition is avoided. In the first correction process, the color conversion definition is performed so that the correspondence between the known points and the known corresponding points is reproduced. Therefore, the accuracy of the corrected color conversion definition is high.
Further, since the correction area to be corrected in the second correction process can be set sufficiently wide, the area where the known point pair contributes to the color conversion definition is wide.

Therefore, the color conversion definition creating method of the present invention
There is a high degree of freedom for known point pairs that are prerequisites for creating
Versatility for various devices is also high. Further, according to the color conversion definition creating method of the present invention, a highly accurate color conversion definition can be created over the entire color reproduction area of the device.

The color conversion definition creating method according to the present invention employs the first
Is a color space in which the color expression region of the device that mediates between the image and the image data is represented by a rectangular parallelepiped or a cube, and the lattice straight line is located on a ridge line of the color expression region in the first color space. It is desirable that they are parallel to each other.

Since the grid straight lines parallel to the ridge lines of the color expression area are orthogonal to each other, a practical color conversion definition is created.

Further, in the color conversion definition creating method according to the present invention, the known point pair includes a known point at the same position as the position of the grid point set in the approximation process. In the process, the position in the second color space of the grid corresponding point corresponding to the grid point at the same position as the position of the acquired known point forming the known point pair is determined by the known corresponding point forming the selected known point pair. The position may be corrected to the same position as the position in the second color space, or the known point pair includes a known point at a position different from the position set in the approximation process of the lattice point. Wherein the first correction step includes, among the predetermined number of grid corresponding points corresponding to each of the predetermined number of grid points whose positions have been set in the approximation step, a known point constituting the acquired known point pair, A certain number of grid points that surround the narrowest in the color space of The corresponding grid points corresponding to the record, may be intended to correct the position in the second color space.

That is, according to the color conversion definition creating method of the present invention, not only the case where the known point pair includes a known point at the same position as the position of the grid point, but also A highly accurate color conversion definition can be created even when a known point pair includes a known point.

Further, the color conversion definition creating method of the present invention
For each of the plurality of known point pairs, each of the known points forming each of the plurality of known point pairs is internally provided with one or more known points.
A method for creating a color conversion definition through a correction area calculation step of calculating so as to exist one by one, wherein the second correction step is obtained in the first correction step among correction areas calculated in the correction area calculation step. The position in the second color space of the grid corresponding point corresponding to the grid point existing in the correction area for the known point pair may be corrected, or the first correction process may be performed by the first correction process. Each time the correction process is performed, one known point pair is selectively acquired from the plurality of known point pairs to correct the position of the grid corresponding point, and the second correction process is performed by the first correction process. It is transmitted every time one known point pair is acquired in the correction process, and among the known points constituting the known point pair that has been acquired in the first modification process in the past, Only known points that make up the known point pair acquired during the correction process Obtains the correction area based on a predetermined algorithm so that resident, may be intended to correct the position in the second color space corresponding grid points corresponding to the lattice points present in the modified area.

According to the color conversion definition creating method through the correction area calculation step, it is easy to balance the areas where each known point pair affects the color conversion definition, and the color conversion definition for obtaining the correction area in the second correction step. According to the creation method, the correction area can be made larger than in the color conversion definition creation method that goes through the correction area calculation process.

A color conversion definition creating apparatus according to the present invention, which achieves the above object, comprises: a grid point where a plurality of grid lines crossing each other in a grid in a predetermined first color space; Defines a coordinate transformation between a first color space and a second color space, which is composed of a set of grid point pairs formed of a set of grid point corresponding points corresponding to grid points in the second color space Is defined as a plurality of known point pairs each consisting of a set of a known point in the first color space and a known corresponding point in the second color space corresponding to the known point. A color conversion definition creating apparatus for creating a position based on a predetermined number of grid points in a first color space, and a second color of a grid corresponding point corresponding to each of the set grid points; The position in space, the distribution of their grid corresponding points in the second color space, In order to approximate the distribution of the known corresponding points constituting each of the plurality of known point pairs, the grid corresponding points corresponding to the grid points linearly arranged in the first color space are defined in the second color space. An approximation process calculated under the condition that they are arranged in a straight line, and a known point pair is selectively obtained from the plurality of known point pairs, and a predetermined number of grid points whose positions are set in the approximation process are respectively Among the predetermined number of grid corresponding points corresponding to the one or more grid corresponding points respectively corresponding to the one or more grid points including the closest grid point to the known point forming the acquired known point pair. A first correction step of correcting the position in the second color space so that coordinate conversion between the known points and the known corresponding points forming the obtained known point pair is reproduced by the color conversion definition; (1) The existing points that constitute the pair of known points Among the grid corresponding points corresponding to the grid points existing inside the correction area obtained by the predetermined algorithm in the first color space so that only one point exists therein, the grid whose position has been corrected in the first correction process A color conversion definition is obtained through a second correction process of correcting the positions of the grid corresponding points other than the corresponding points in the second color space by a correction amount corresponding to the correction amount of the position corrected grid corresponding points. It is characterized in that it is created.

In order to achieve the above object, the present invention provides a color conversion definition creating program storage medium comprising: a plurality of grid lines crossing each other in a grid in a predetermined first color space; A coordinate conversion between a first color space and a second color space, which is a set of grid point pairs in a predetermined second color space, which is a set of grid point corresponding points corresponding to the grid points. Are defined as a plurality of known points each consisting of a set of a known point in the first color space and a known corresponding point in the second color space corresponding to the known point. A color conversion definition creating program storage medium storing a color conversion definition creating program created based on a pair, wherein a position in a first color space of each of a predetermined number of grid points is set, and the position is set. In the second color space of the grid corresponding point corresponding to each grid point The positions in the first color space are linearly adjusted so that the distribution of the grid corresponding points in the second color space approximates the distribution of the known corresponding points constituting each of the plurality of known point pairs. The approximation process of calculating under the condition that the grid corresponding points corresponding to the grid points arranged in a line are linearly arranged in the second color space, and a known point pair from the plurality of known point pairs Of the predetermined number of grid corresponding points corresponding to each of the predetermined number of grid points that are selectively acquired and whose positions have been set in the approximation process, the lattice point closest to the known point forming the acquired known point pair The positions in the second color space of the one or more grid corresponding points corresponding to the one or more grid points, respectively, include the coordinates between the known points forming the acquired known point pair and the known corresponding points. Fixed conversion to be reproduced by color conversion definition A first correction process to be performed, and a first correction process that exists within a correction area determined by a predetermined algorithm in the first color space so that only one known point that forms the known point pair obtained in the first correction process exists therein. The positions of the grid corresponding points in the second color space other than the grid corresponding points whose positions have been corrected in the first correction process among the grid corresponding points corresponding to And a second conversion process of correcting the color conversion definition by the correction amount according to the correction amount.

The color conversion definition creating program and the color conversion definition creating apparatus according to the present invention are only shown here in their basic form, but this is merely to avoid duplication. The color conversion definition creation program and the color conversion definition creation device of the present invention include not only the color conversion definition creation program and the color conversion definition creation device of the above-described basic form but also each of the above-described color conversion definition creation methods. And various types of color conversion definition creation programs and color conversion definition creation devices.

[0047]

Embodiments of the present invention will be described below.

FIG. 2 is an overall configuration diagram of an image input-color conversion-image output system to which one embodiment of the present invention is applied.

Here, a color scanner 10 is shown, and the color scanner 10 reads an original image 11 and generates RGB three-color image data. This R
The GB image data is input to the personal computer 20. In the personal computer 20, the image data obtained by the color scanner 10 is converted into image data of three colors of RGB for image output suitable for a color printer 30 described later. The image data for image output is input to the color printer 30, and the color printer 30
In, print output based on the input image data is performed, and a print image 31 is formed.

Here, the personal computer 20
Also serves as an embodiment of a color conversion definition creating apparatus according to the present invention. In this personal computer 20, a color conversion definition is created in advance, and image data obtained by the color scanner 10 is converted into an image for the color printer 30. When converting to data, the created color conversion definition is referred to. The color conversion definition and a method for creating the color conversion will be described later.

In the system shown in FIG. 2, a color scanner for reading an original image and generating image data is shown as an example of an input device for inputting an image and obtaining image data. In addition to a color scanner, for example, a DSC (digital still camera), a system that records an image on the reversal film by photographing using a reversal film, reads the recorded image with a color scanner or the like, and obtains image data, Any other device may be used as long as an image is input to obtain image data.

In the system shown in FIG. 2, the color printer 30 is shown as an example of an output device for outputting an image based on image data.
0 may be an electrophotographic color printer,
It may be an inkjet type color printer,
The printer may be of a type that exposes the photographic paper with the modulated laser beam and develops the photographic paper, and does not matter what the printing method is. The output device is not limited to a printer, but may be a printing machine or a CR that displays an image on a display screen.
An image display device such as a T display device or a plasma display device may be used.

However, here, a description will be given on the assumption that the system includes a color scanner 10 and a color printer 30 as examples of the input device and the output device.

A feature of the system shown in FIG. 2 as one embodiment of the present invention resides in the content of processing executed inside the personal computer 20, and the personal computer 20 will be described below.

FIG. 3 is an external perspective view of the personal computer 20 shown by one block in FIG. 2, and FIG. 4 is a hardware configuration diagram of the personal computer 20.

The personal computer 20 has a main body device 21, an image display device 22 for displaying an image on a display screen 22 a in response to an instruction from the main body device 21, and a main device 21 in response to a key operation. A keyboard 23 for inputting various types of information, and a mouse 2 for designating an arbitrary position on the display screen 22a to input an instruction corresponding to, for example, an icon displayed at the position.
4 is provided. The main unit 21 has a floppy disk loading port 21a for loading a floppy disk, and a CD-ROM for loading a CD-ROM.
It has a ROM loading port 21b.

As shown in FIG. 4, a main memory 21 which executes various programs and a program stored in a hard disk drive 213 are read out and expanded for execution by the CPU 211 inside the main unit 21 as shown in FIG.
2. A hard disk drive 213 storing various programs, data, etc., an FD drive 214 for loading the floppy disk 100 and accessing the loaded floppy disk 100, a CD-ROM 110 loaded, and the loaded CD-ROM 110 A CD-ROM drive 215 to be accessed, connected to the color scanner 10 (see FIG. 2), an input interface 216 for receiving image data from the color scanner 10, and connected to a color printer 30 (see FIG. 2). An output interface 217 for sending the image data, the image display device 22, the keyboard 23, and the mouse 24 shown in FIG.
5 are interconnected.

Here, the CD-ROM 110 stores a color conversion definition creating program for operating the personal computer 20 as a color conversion definition creating device. The CD-ROM 110 is loaded into the CD-ROM drive 215. Then, the color conversion definition creating program stored in the CD-ROM 110 is uploaded to the personal computer 20 and the hard disk drive 2
13 is stored. The CD-ROM 110 in which the color conversion definition creating program is stored is an embodiment of the color conversion definition creating program storage medium of the present invention, and the hard disk device 213 in which the color conversion definition creating program is uploaded and stored is also included. Is an embodiment of a color conversion definition creation program storage medium.

Next, a method of creating a color conversion definition by the color conversion definition creating program uploaded to the personal computer 20 will be described.

Here, the color scanner 10 and the color printer
Color space depending on each device such as the linter 30 (here
Then, an RGB color space) and a common color space (here, L^*a^*b^*
Color conversion definition that defines the color conversion between
It shall be created for each chair. Also, RGB color space
Is an example of a first color space according to the present invention, and L^*a^*b
^*The color space is an example of the second color space according to the present invention.

FIG. 5 is a flowchart showing an example of a color conversion definition creating method using a color conversion definition creating program executed in the personal computer 20.

Here, the approximation process (step S10)
1), the first correction process (step S103), and the second
A color conversion definition is created through a correction process (step S104). Here, in order to prepare a balanced correction area in advance, an approximation process (step S10) is performed.
After 1), a correction area calculation process (step S102) is provided.

The first correction process (step S103) and the second correction process (step S104) are processes that are repeated once for each pair of known points, and are performed based on a color chart or the like. (Step S1)
05). The color conversion definition is as shown in Table 1 above.
Although a set of lattice point pairs is created, a set of lattice point pairs corresponding to an approximate color conversion definition is created in the approximation process (step S101), and each time a first modification process or a second modification process is performed thereafter. Then, the grid point pairs forming the color conversion definition are corrected, and finally, a set of grid point pairs forming the high-precision color conversion definition is created.

Hereinafter, each of these steps will be sequentially described. However, in the following description, as described above, “find a point” without particularly distinguishing the position of the point in the color space from the point itself.
It may be expressed as etc.

FIG. 6 is an explanatory diagram of the approximation process.
6A shows the RGB color space two-dimensionally for convenience, and FIG. 6B shows the L ^* a ^* b ^* color space similarly two-dimensionally.

First, in the approximation process in step S101 in FIG. 5, the number of grid points 41 in the color representation area represented by the cube 40 in the RGB color space is set sufficiently large within the range permitted by the storage capacity of the personal computer. A grid corresponding point 42 in the L ^* a ^* b ^* color space corresponding to each of the grid points 41 is formed by a plurality of known point pairs as shown in Table 2 by the method described in the third profiling. Is calculated based on A set of grid point pairs including such grid points 41 and grid corresponding points 42 forms an approximate color conversion definition. However, in this approximation process, a first-order polynomial is always used, and the grid corresponding line 44 in the L ^* a ^* b ^* color space corresponding to the grid line 43 in the RGB color space is a straight line. As a result, the color expression area in the L ^* a ^* b ^* color space is approximated by the octahedron 45, and the breakdown of the color conversion definition near the peripheral surface of the color expression area is avoided.

FIG. 7 is an explanatory diagram of the correction area calculation process.

FIG. 7 shows the RGB values as in FIG.
The color space is shown two-dimensionally, and an example of known points 46 forming each of a plurality of known point pairs as shown in Table 2 is also shown.

In the correction area calculation process in step S102 in FIG. 5, a correction area 47 as described below is calculated for each known point 46 (ie, for each known point pair).

The correction area 47 calculated here is an example of the correction area according to the present invention, and is a spherical area centered on each known point 46, and the radius of the spherical area is different from other known points. Is calculated so as to be as large as possible as long as it is not included. Accordingly, the correction areas 47 may overlap each other, but there is always only one known point 46 in one correction area 47, and the correction areas 47 are well-balanced.

FIG. 8 is an explanatory diagram of the first correction process. As in FIG. 6, FIG. 8A shows an RGB color space, and FIG. 8B shows an L ^* a ^* b ^* color space of 2 colors. Dimensionally shown.

In the first correction process in step S103 of FIG. 5, one known point pair is selectively obtained from a plurality of known point pairs including the plurality of known points 46 illustrated in FIG. FIG. 8A shows known points 46 constituting the acquired known point pair, and also shows grid points 41 set in the approximation process. Here, the known point 46
Exists at the same position as the position of one grid point, that is, the known point 46 overlaps the grid point. FIG.
(B) shows the known corresponding points 48 constituting the acquired known point pair, and also shows the grid corresponding points 42 corresponding to the grid points at the same positions as the positions of the known points 46.

When the known point pair is acquired, the position of the grid corresponding point 42 corresponding to the grid point overlapping the known point 46 forming the known point pair constitutes the known point pair. The position is corrected to the same position as the position of the known corresponding point 48.
As a result, the grid line 44 corresponding to the grid line 43 in the RGB color space is corrected to a polygonal line.

Since the correspondence between the known point 46 and the known corresponding point 48 is a correspondence obtained by colorimetry or the like, these points are represented by the coordinates of the RGB color space and the L ^* a ^* b ^* color space. It represents the exact correspondence with the coordinates. Then, by correcting the position of the grid corresponding point 42 to the same position as the position of the known corresponding point 48, the color conversion definition reproduces the coordinate conversion between the known point 46 and the known corresponding point 48. Thus, an accurate correspondence relationship is reproduced around the known point 46 and the known corresponding point 48.

Here, a method of correcting the grid corresponding point 42 when the position of the known point 46 does not overlap with any of the grid points 41 will be described.

FIG. 9 is an explanatory diagram of a method of correcting grid corresponding points when the position of a known point does not overlap with any grid point.

FIG. 9A two-dimensionally shows a known point 46 and a lattice point 41 surrounding the known point 46. Since the lattice point 41 is actually located at the vertex of the cube 49, there are eight lattice points.
Two grid points 41 are shown. In FIG. 9B, a known corresponding point 48 and a grid corresponding point 42 corresponding to the known point 46 and the grid point 41, respectively, are shown two-dimensionally. Furthermore, in the FIG. 9 (B), the lattice corresponding point 42a after being modified as will be described below in accordance with the position of known corresponding points 48, the position correction amount d _i of each corresponding grid points 42 are illustrated ing.

Here, in correcting the grid corresponding point 42, first, based on the relative position of the known point 46 with respect to the cube 49 surrounded by the grid point 41, and the coordinates of each grid corresponding point 42 before correction. A so-called volume interpolation operation represented by the following equation is performed, and a calculation corresponding point 50 corresponding to the known point 46 is calculated.

[0079] _{L = L 1 V 1 + L} 2 V 2 + ... + L 8 V 8 a = a 1 V 1 + a 2 V 2 + ... + a 8 V 8 b = b 1 V 1 + b 2 V 2 + ... + b 8 V ₈ where V ₁ + V ₂ +... + V ₈ = 1 Here, L, a, and b are the coordinates of the calculation corresponding point 50,
L _i , a _i , and b _i (i = 1,..., 8) are the coordinates of each grid corresponding point 42 before correction. Also, V _i (i = 1,...,
8) is a coefficient of the volume interpolation operation, and the known point 46 is interposed between the grid points 41 corresponding to the grid corresponding points 42 in the divided area 51 in which the cube 49 is divided into eight based on the known points 46. Corresponds to the volume of the divided area 51 facing each other. However, these values are values standardized with the volume of the cube 49 as 1.

Next, a difference D between the known corresponding point 48 and the calculated corresponding point 50 is determined. Based on the difference D, the position correction amount d _i (i = 1,
.., 8) are calculated. The following equation is an example of an equation that matches the result of the volume interpolation operation based on the coordinates of each corrected grid corresponding point 42a with the known corresponding point 48.

D = d ₁ V ₁ + d ₂ V ₂ +... + D ₈ V ₈ where d _i = dV _i , (i = 1,..., 8) where d is a proportional coefficient. Coefficient of volume interpolation calculation V _i
Since (i = 1,..., 8) and the difference D are known, the proportional coefficient d and each position correction amount d _i (i = 1,..., 8) can be calculated.

Each position correction amount d calculated in this way
By correcting the position of each grid corresponding point 42 by _i (i = 1,..., 8), the color conversion definition reproduces the coordinate conversion between the known point 46 and the known corresponding point 48. . In other words, even when the known point 46 does not overlap the grid point 41, the position of the grid corresponding point 42 is set so that the coordinate conversion between the known point 46 and the known corresponding point 48 is reproduced by the color conversion definition. Can be modified.

In the following description, the known point 46 is the grid point 41
Only the case where they overlap will be described.

FIG. 10 is an explanatory diagram of the second correction process.
As in FIG. 6, FIG. 10A shows an RGB color space, and FIG.
(B) shows the L ^* a ^* b ^* color space two-dimensionally.

FIG. 10 (A) shows FIG. 8 (A) and FIG.
A known point 46 forming a known point pair acquired in the first modification process described with reference to (B) is shown, and the known region pair is calculated for the known region in the above described modified region calculation process. 47 is also shown.

In the second correction process, among the grid points 41 set in the approximation process, the grid points 4 existing in the correction area 47
The position of the grid corresponding point 42b corresponding to 1b is corrected.
However, since the position of the grid corresponding point 42a corresponding to the grid point overlapping the known point 46 has already been corrected in the first correction process, it is not subject to the position correction in the second correction process.

The correction amount of the position of each grid corresponding point 42b is equal to or smaller than the correction amount of the grid corresponding point 42a whose position has been corrected in the first correction process. Smaller away from. By correcting the position by such a correction amount, each grid corresponding point 42b
Is corrected to the position indicated by the black dot 42c in FIG. With such correction, the position correction in the first correction process is reflected on the entire correction area 47, and the accuracy of the color conversion definition is improved.

The first correction process and the second correction process described above include:
By repeating until a plurality of known point pairs are all acquired (see step S105 in FIG. 5), the shape of the grid corresponding line 44 is successively corrected, and finally, a polygonal line corresponding to the curve 4 shown in FIG. Is obtained, and a high-precision color conversion definition is created.

In the color conversion definition creating method of the present invention, the correction in the second correction process is performed after the acquisition and the correction in the first correction process for all the plurality of known point pairs. Is also good.

Next, another example of the color conversion definition creating method of the present invention which is different from the example shown in the flowchart of FIG. 5 will be described.

FIG. 11 is a flowchart showing another example of the color conversion definition creating method of the present invention.

In the example shown in FIG. 11, similar to the example shown in FIG. 5, the color conversion definition is performed through an approximation process (step S201), a first correction process (step S202), and a second correction process (step S203). Is created, and unlike the example shown in FIG. 5, the correction area calculation process is not performed.

Also, as in the example shown in FIG. 5, the first correction process (step S202) and the second correction process (step S203) are repeated until all of a plurality of known point pairs are obtained (step S204). .

Further, the approximation process (step S201) and the first correction process (step S20) shown in FIG.
The contents executed in 2) include an approximation process (step S101) and a first correction process (step S101) shown in FIG.
103) is exactly the same as the content executed in step 103), and a duplicate description will be omitted.

In the second correction process (step S203) shown in FIG. 11, first, a correction area is calculated as described later, and the position of a grid corresponding point corresponding to a grid point in the calculated correction area is determined as shown in FIG. (Step S10)
Modified as in 4).

Hereinafter, a method of calculating the correction area in the second correction process (step S203) shown in FIG. 11 will be described.

FIG. 12 is an explanatory diagram of a method of calculating a correction area in the second correction process.

FIG. 12 shows a plurality of known points 46a and 46b constituting a plurality of known point pairs acquired by repeating the first correction process a plurality of times. The correction area 47 is calculated as a spherical area centered on a known point 46a that forms a pair of known points acquired in the first correction process executed immediately before, and the radius of the correction area 47 is the center known point 46a. Is calculated so as to be as large as possible as long as it does not include other known points 46b except for. Since the correction area 47 calculated in this manner is wider than the correction area calculated in the correction area calculation step described with reference to FIG. 7, the correction area 47 is calculated in the first correction step according to the known point pair including the center known point 46a. The performed position correction is more widely reflected, and a highly accurate color conversion definition is created.

After the position of the grid corresponding point is corrected based on the correction area 47 calculated in the second correction step, the first correction step is repeated, and the known point 46c existing in the correction area 47 is determined. When a known point pair including the known point 46c is acquired, re-correction according to the known point pair including the known point 46c is performed on the grid corresponding point in the first correction process and the second correction process. However, even when re-correction is performed, the correction area 47 is calculated as described above, so that re-correction of a grid corresponding point whose position has already been corrected in the first correction process is avoided.

In each of the above-described examples of the color conversion definition creating method, a spherical correction area is employed. However, the shape of the correction area according to the present invention is not limited to a spherical shape.
The shape may be an ellipse, or a cube or a rectangular parallelepiped. In addition, the known point existing in the correction area does not necessarily need to be located at the center of the correction area, and may be located at a biased position in the correction area.

In each of the above examples, the correction area is calculated so as to be as large as possible unless other known points are included. In the color conversion definition creating method of the present invention, the size of the correction area is fixed. An upper limit may be determined.

Next, an embodiment of the color conversion definition creating program storage medium of the present invention will be described.

FIG. 13 is a diagram showing an embodiment of the color conversion definition creating program storage medium of the present invention.

In the above, with reference to FIG. 4, it has been described that each of the CD-ROM 110 and the hard disk device 213 storing the color conversion definition creating program is an embodiment of the color conversion definition creating program storage medium. In FIG. 13, a CD-ROM 110 storing a color conversion definition creating program 111 for operating the personal computer 20 shown in FIGS. It is illustrated as one embodiment of a program storage medium.

The color conversion definition creating program 111 stored in the CD-ROM 110 as an example of the color conversion definition creating program according to the present invention stores the color conversion definition by the color conversion definition creating method described with reference to FIG. A portion 11 for executing the approximation process, the correction region calculation process, the first correction process, and the second correction process shown in FIG.
2, 113, 114, and 115.

Next, with reference to FIGS. 14 to 18, variations of the scene to which the color conversion definition creating method of the present invention is applied will be described.

FIG. 14 is a diagram showing a scene where a color printer is used as a device.

FIG. 14 shows a color printer 301. The color printer 301 is an output device that receives an input of image data in the RGB data format and outputs an image.

When a color conversion definition is created, RGB chart data 303 representing an image of a color chart 302 is input to the color printer 301, and the color chart 302 is output. The RGB chart data 303 includes the coordinate values of the RGB color space, which represent the colors of the respective color patches 302a constituting the color chart 302, and these coordinate values correspond to the above-described known points. .

Each color patch 302a of the color chart 302 output from the color printer 301 is measured by the colorimeter 304 to obtain the chart colorimetric data 30.
5 is obtained. The chart colorimetric data 305 includes colorimetric values (L ^* a ^* b ^* values and XY) for each color patch 302a.
Z value), and these colorimetric values are L ^* a ^* b ^*
It is a coordinate value in a color space or an XYZ color space, and corresponds to the above-described known corresponding point.

[0111] Each coordinate value included in the RGB chart data 303 and each colorimetric value included in the chart colorimetric data 305 are associated with each other via each color patch 302a of the color chart 302. As a result, the above-described set of known point pairs is obtained.

On the basis of the set of known point pairs obtained in this way, a color defining the correspondence between the coordinate values in the L ^* a ^* b ^* color space or the XYZ color space and the coordinate values in the RGB color space. The conversion definition is created by the color conversion definition creation method (profiling) as described above.

Note that a general image may be used in place of the color chart 302 as long as the image portion corresponding to the color patch 302a is an image that can be specified. When such a general image is used,
Each coordinate value included in the RGB chart data 303 and each colorimetric value included in the chart colorimetric data 305 are associated with each other via each image portion. In the following description, only the case where the color chart 302 is used will be described, and the description of the case where a general image is used will be omitted.

FIG. 15 is a diagram showing a scene where a color scanner is used as a device.

FIG. 15 shows a color scanner 306. The color scanner 306 is an input device that reads a document image and generates image data in the RGB data format.

When a color conversion definition is created, an image of the color chart 302 is read by the color scanner 306, and scan data 307 is generated.
The scan data 307 includes a color chart 302
Represents the color of each color patch 302a constituting
The coordinate values in the GB color space are included, and these coordinate values correspond to the above-described known points.

As in the description with reference to FIG. 14, each color patch 302a of the color chart 302 is measured by the colorimeter 304 to obtain chart colorimetric data 305.

Then, the coordinate values included in the scan data 307 and the respective colorimetric values included in the chart colorimetric data 305 are associated with each other in the same manner as described above, so that the above-described set of known point pairs is obtained. Is obtained.

On the basis of the set of known point pairs obtained in this manner, a color defining the correspondence between the coordinate values in the L ^* a ^* b ^* color space or the XYZ color space and the coordinate values in the RGB color space. A conversion definition is created.

FIG. 16 is a diagram showing another scene in which a color scanner is used as a device.

In the scene shown in FIG. 16, similarly to the scene shown in FIG. 15, the image of the color chart 302 is read by the color scanner 306, and the scan data 3 is read.
07 is generated.

The dye density of each color patch 302a of the color chart 302 is measured by the densitometer 308, and chart density data 309 is obtained. The chart density data 309 includes a dye density value for each color patch 302a.
A coordinate value in the my color space, which corresponds to the above-described known corresponding point.

Then, the coordinate values included in the scan data 307 and the dye density values included in the chart density data 309 are associated with each other in the same manner as described above, whereby the above-described set of known points is obtained. Can be

Based on the set of known point pairs obtained in this way, a color conversion definition that defines the correspondence between the coordinate values in the cmy color space and the coordinate values in the RGB color space is created.

FIG. 17 is a diagram showing a scene in which a digital still camera is used as a device.

FIG. 17 shows a digital still camera 310.
An input device 10 captures a landscape or the like and generates image data in the RGB data format.

When a color conversion definition is created, the digital still camera 310 uses the color chart 30
2 is photographed, and photographing data 311 is generated. The photographing data 311 also includes the coordinate values of the RGB color space representing the colors of the respective color patches 302a constituting the color chart 302. In the same manner as described above, these coordinate values correspond to the known points described above. Is equivalent to

As in the description with reference to FIG. 14, each color patch 302a of the color chart 302 is measured to obtain chart colorimetric data 305.

The coordinate values included in the photographing data 311 and the respective colorimetric values included in the chart colorimetric data 305 are associated with each other in the same manner as described above, so that the above-described set of known point pairs is obtained. Is obtained, and a color conversion definition that defines the correspondence between the coordinate values in the L ^* a ^* b ^* color space or the XYZ color space and the coordinate values in the RGB color space is created.

FIG. 18 is a diagram showing a scene where an analog camera is used.

FIG. 18 shows an analog camera 312. When a color conversion definition is created, the color chart 302 is photographed by the analog camera 312 to obtain a photographic film 313. Then, the image shown on the photographic film 313 is read by the color scanner 306, and scan data 307 is generated. Alternatively, the pigment density of the photographing film 313 is measured by the densitometer 308 and the chart density data 3
09 is obtained. In other words, here, the analog camera 3
An input device is constituted by a combination of the color scanner 12 and the color scanner 306 or a combination of the analog camera 312 and the densitometer 308. The RGB color space coordinate values included in the scan data 307 and the dye density values included in the chart density data 309 all correspond to the above-described known points.

As in the description with reference to FIG. 14, each color patch 302a of the color chart 302 is measured to obtain chart colorimetric data 305. The colorimetric values included in the chart colorimetric data 305 correspond to the known corresponding points described above.

The RGB color space coordinate values included in the scan data 307 and the dye density values included in the chart density data 309 and the chart colorimetric data 305
Are associated with each other via the respective color patches 302a of the color chart 302, thereby obtaining the above-described set of known points.

On the basis of the set of known point pairs obtained in this manner, a color defining the correspondence between the coordinate values in the cmy color space and the coordinate values in the L ^* a ^* b ^* color space and the XYZ color space. A conversion definition is created, or coordinate values in the RGB color space,
A color conversion definition is created that defines the correspondence with the coordinate values in the L ^* a ^* b ^* color space and the XYZ color space.

The color conversion definition created in the scene shown in FIG. 18 is, for example, image data obtained by photographing a person with an analog camera 312 and reading a photographic film 313 by a color scanner 306, or the photographic film. Reference numeral 313 is used to obtain a colorimetric value of the skin color of the person based on the density data obtained by measurement by the densitometer 308.

[0136]

As described above, according to the present invention,
There is a high degree of freedom for known point pairs that are prerequisites for creating
A highly accurate color conversion definition can be created up to an area boundary of a color expression area by a color conversion definition creating method that is highly versatile for various devices. Therefore, when creating a color conversion definition, it is possible to use existing charts such as the IT8 chart and Macbeth chart in which patch rules are predetermined, and charts that focus on patches of important colors. it can.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram illustrating color conversion according to a color conversion definition.

FIG. 2 is an overall configuration diagram of an image input-color conversion-image output system to which an embodiment of the present invention is applied.

FIG. 3 is an external perspective view of the personal computer.

FIG. 4 is a hardware configuration diagram of a personal computer.

FIG. 5 is a flowchart showing a color conversion definition creating method by a color conversion definition creating program executed in a personal computer.

FIG. 6 is an explanatory diagram of an approximation process.

FIG. 7 is an explanatory diagram of a correction area calculation process.

FIG. 8 is an explanatory diagram of a first correction process.

FIG. 9 is an explanatory diagram of a method of correcting grid corresponding points when the position of a known point does not overlap with any grid point.

FIG. 10 is an explanatory diagram of a second correction process.

FIG. 11 is a flowchart showing another example of the color conversion definition creating method of the present invention.

FIG. 12 is an explanatory diagram of a method of calculating a correction area in a second correction process.

FIG. 13 is a diagram showing an embodiment of a color conversion definition creating program storage medium of the present invention.

FIG. 14 is a diagram illustrating a scene in which a color printer is used as a device.

FIG. 15 is a diagram illustrating a scene where a color scanner is used as a device.

FIG. 16 is a diagram showing another scene in which a color scanner is used as a device.

FIG. 17 is a diagram showing a scene in which a digital still camera is used as a device.

FIG. 18 is a diagram illustrating a scene where an analog camera is used.

[Explanation of symbols]

 Reference Signs List 10 color scanner 11 original image 20 personal computer 21 main unit 21a floppy disk loading slot 21b CD-ROM loading slot 22 image display device 22a display screen 23 keyboard 24 mouse 30 color printer 31 print image 40 cube 41, 41b grid points 42, 42a , 42b grid corresponding point 43 grid straight line 44 grid corresponding line 45 octahedron 46, 46a, 46b, 46c known point 47 modified area 48 known corresponding point 49 cube 50 calculation corresponding point 51 divided area 100 floppy disk 110 CD-ROM 111 color conversion Definition creation program 211 CPU 212 Main memory 213 Hard disk drive 214 FD drive 215 CD-ROM drive 301 Color printer 302 Color chart 302a Color Pitch 303 RGB chart data 304 colorimeter 305 chart color data 306 measured color scanner 307 scan data 308 densitometer 309 chart density data 310 digital still camera 311 photographing data 312 analog camera 313 photographing film

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) LA02 LB02 NA03 NA15 NA29 PA03 PA08

Claims (8)

[Claims] 1. A method according to claim 1, wherein a plurality of grid lines intersecting each other in a grid in a predetermined first color space intersect with each other, and a grid point in a predetermined second color space is connected to the grid point. A color conversion definition that defines a coordinate conversion between the first color space and the second color space, which is a set of grid point pairs including a set of corresponding grid point corresponding points, Color conversion definition creation based on a plurality of pairs of known points in the first color space and corresponding known points in the second color space and corresponding to the known points. A method for setting a position in the first color space of each of a predetermined number of grid points, and determining a position in the second color space of a grid corresponding point corresponding to each of the set grid points, The distribution of the grid corresponding points in the second color space is defined by the plurality of known point pairs, respectively. The grid corresponding points corresponding to the grid points linearly arranged in the first color space are linearly arranged in the second color space so as to approximate the distribution of the configured known corresponding points. An approximate process of calculating under the condition that there is a predetermined number of grid points whose positions are set in the approximation process by selectively obtaining a known point pair from the plurality of known point pairs. Out of the grid corresponding points of the one or more grid corresponding points respectively corresponding to one or more grid points including the closest grid point to the known point forming the acquired known point pair, A first correction step of correcting a position in a color space such that coordinate conversion between a known point and a known corresponding point forming the obtained known point pair is reproduced by a color conversion definition; The known points that make up the known point pair obtained in Of the corresponding grid corresponding point to the lattice points existing inside the correction area obtained by a predetermined algorithm in the first color space such that only one present in the section, the first
A second correction unit that corrects the positions in the second color space of the grid corresponding points other than the grid corresponding points whose positions have been corrected in the correction process by a correction amount according to the correction amount of the position corrected grid corresponding points; A color conversion definition creating method, wherein the color conversion definition is created through a correction process. 2. The first color space, wherein a color representation area of a device that mediates between an image and image data is represented by a rectangular parallelepiped or a cube, and the grid line is defined by the first color. 2. The color conversion definition creating method according to claim 1, wherein the color conversion definition is parallel to a ridge line of the color expression area in the space. 3. The known point pair includes a known point of the grid point at the same position as a position set in the approximation process, and the first correction process determines the acquired known point pair. The position in the second color space of the grid corresponding point corresponding to the grid point at the same position as the position of the known point to be formed is the position in the second color space of the known corresponding point forming the selected known point pair. 2. The color conversion definition creating method according to claim 1, wherein the correction is made to the same position as that of the color conversion definition. 4. The known point pair includes a known point of the grid point at a position different from a position set in the approximation step, and the first correction step includes a position in the approximation step. Among the predetermined number of grid corresponding points corresponding to each of the predetermined number of grid points for which
2. The color conversion definition creation according to claim 1, wherein the position of the grid corresponding point corresponding to each of a predetermined number of grid points that surrounds the narrowest in the color space is corrected in the second color space. Method. 5. A correction area calculating step of calculating the correction area for each of the plurality of known point pairs such that each of the known points constituting each of the plurality of known point pairs exists therein. A color conversion definition creating method, wherein the second correction step exists in a correction area for a known point pair obtained in the first correction step among correction areas calculated in the correction area calculation step. 2. The color conversion definition creating method according to claim 1, wherein the position of the grid corresponding point corresponding to the grid point to be corrected in the second color space is corrected. 6. The method according to claim 1, wherein the first correction step comprises obtaining one known point pair from the plurality of known point pairs each time the first correction step is performed, and obtaining a position of the grid corresponding point. Wherein the second correction step is such that the number of known points is 1 in the first correction step.
Of the known points constituting the pair of known points acquired in the first correction process in the past, and the known points acquired in the first correction process passed immediately before. Determine the correction area based on the predetermined algorithm so that only known points constituting a point pair exist inside,
2. The color conversion definition creating method according to claim 1, wherein a position in the second color space of a grid corresponding point corresponding to a grid point existing in the correction area is corrected. 7. A grid point in which a plurality of grid lines crossing each other in a grid pattern in a predetermined first color space cross each other, and a grid point in a predetermined second color space. A color conversion definition that defines a coordinate conversion between the first color space and the second color space, which is a set of grid point pairs including a set of corresponding grid point corresponding points, Color conversion definition creation based on a plurality of pairs of known points in the first color space and corresponding known points in the second color space and corresponding to the known points. An apparatus, wherein a position of each of a predetermined number of grid points in the first color space is set, and a position in the second color space of a grid corresponding point corresponding to each of the set grid points, The distribution of those grid corresponding points in the second color space is
In order to approximate the distribution of known corresponding points constituting each of the plurality of known point pairs, the grid corresponding points corresponding to the grid points linearly arranged in the first color space are the second color points. An approximation process of calculating under the condition that they are linearly arranged in space, and selectively acquiring a known point pair from the plurality of known point pairs, and a predetermined number of positions whose positions are set in the approximation process. One or more grids corresponding to one or more grid points each including one or more grid points closest to a known point forming the acquired known point pair, out of a predetermined number of grid corresponding points corresponding to the grid points, respectively. A first correction that corrects the position of the corresponding point in the second color space so that the coordinate conversion between the known point and the known corresponding point forming the obtained known point pair is reproduced by the color conversion definition. And obtaining in the first correcting step Among the grid corresponding points corresponding to the grid points existing inside the correction area obtained by the predetermined algorithm in the first color space so that only one known point constituting the known point pair exists therein, 1
A second correction unit that corrects the positions in the second color space of the grid corresponding points other than the grid corresponding points whose positions have been corrected in the correction process by a correction amount according to the correction amount of the position corrected grid corresponding points; A color conversion definition creating apparatus for creating the color conversion definition through a correction process. 8. A grid point where a plurality of grid lines crossing each other in a grid pattern in a predetermined first color space cross each other, and a grid point in a predetermined second color space. A color conversion definition that defines a coordinate conversion between the first color space and the second color space, which is a set of grid point pairs including a set of corresponding grid point corresponding points, Color conversion definition creation based on a plurality of pairs of known points in the first color space and corresponding known points in the second color space and corresponding to the known points. A color conversion definition creating program storage medium storing a program, wherein a position of each of a predetermined number of grid points in the first color space is set, and a grid corresponding point corresponding to each of the set grid points. The position in the second color space in the second color space. Distribution of their corresponding grid points,
In order to approximate the distribution of known corresponding points constituting each of the plurality of known point pairs, the grid corresponding points corresponding to the grid points linearly arranged in the first color space are the second color points. An approximation process of calculating under the condition that they are linearly arranged in space, and selectively acquiring a known point pair from the plurality of known point pairs, and a predetermined number of positions whose positions are set in the approximation process. One or more grids corresponding to one or more grid points each including one or more grid points closest to a known point forming the acquired known point pair, out of a predetermined number of grid corresponding points corresponding to the grid points, respectively. A first correction that corrects the position of the corresponding point in the second color space so that the coordinate conversion between the known point and the known corresponding point forming the obtained known point pair is reproduced by the color conversion definition. And obtaining in the first correcting step Among the grid corresponding points corresponding to the grid points existing inside the correction area obtained by the predetermined algorithm in the first color space so that only one known point constituting the known point pair exists therein, 1
A second correction unit that corrects the positions in the second color space of the grid corresponding points other than the grid corresponding points whose positions have been corrected in the correction process by a correction amount according to the correction amount of the position corrected grid corresponding points; A color conversion definition creation program storage medium, which stores a color conversion definition creation program for creating the color conversion definition through a correction process.