JPH10243246A - Color point corresponding method and recording medium recording computer program for executing processing therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide as much as possible a high-quality color point corresponding result. SOLUTION: A straight line ht, parallel to a saturation axis passing through a color point P and a straight line gh parallel to an axis L*, are sought. An intersection At of L*-axis and straight line ht and an inter-section Bt of the peripheral edge of crossing plane area Jt and straight line ht are found. Intersections Ct and Dt between the peripheral edge of crossing planar area Jt and the straight line gt are found. A ratio (m) between the lengths of line segments AtP and AtBt and a ratio (n) between the lengths of line segments CtP and CtDt are found. While assuming a color point P' in a crossing planar area Js, a straight line hs, parallel to a saturation axis passed through the color point P' and a straight line gs parallel to the L*-axis, are found. An intersection As between the L*-axis and the straight line hs and an intersection Bs between the peripheral edge of crossing planar area Js and the straight line hs are found and intersections Cs and Ds between the peripheral edge of crossing planar area Js and the straight line gs are found. A ratio m' between the lengths of line segments AsP' and AsBs and a ratio n' between the lengths of the line segments CsP' and CsDs are found. The color point P' is rearranged, so as to establish the conditions m'=m and n'=n, and the color point P is made to correspond to the color point P'.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for associating a color point belonging to a first color solid with a color point belonging to a second color solid with respect to first and second color solids existing in a color space. And a color point associating technique.

[0002]

2. Description of the Related Art In the field of printing and plate making, when a large amount of printed matter is printed by a printing machine on the basis of image data, there is a demand for knowing how the print result will be before printing. . Therefore, before printing a large amount, as a simulation, a small amount of printing is performed using a simple proofing machine such as a thermal sublimation printer or an ink jet printer, and the result of the printing is checked in advance.

A device such as the above-described printing machine is hereinafter referred to as a target device, and a device such as the above-described simple proofing machine is hereinafter referred to as a simulating device.

Now, an appropriate color space (for example, L
^(* a ^* b ^* color space), if all colors that can be reproduced by a certain device are plotted as color points, a solid is created in that color space. The solid is a color solid (gamut) unique to the device,
It represents the range of colors that can be reproduced by the device, and the three-dimensional surface corresponds to the limit of colors that can be reproduced by the device.

Therefore, each of the above-described target device and the simulated device has a unique color solid. Now, assuming that the color solid of the simulated device includes all the color solids of the target device, all colors reproduced by the target device can be reproduced by the simulated device as they are.

[0006] However, it is rare that such an inclusive relation is established, and some colors reproduced by the target device cannot be reproduced by the simulated device.

Therefore, if the image data (ie, color data) given to the target device is given to the simulating device as it is when performing the above-mentioned simulation, the print result (especially the printed color) will be what. A problem arises in that it is not possible to correctly confirm in advance.

Therefore, in such a case, all colors reproduced by the target device are simulated while substituting colors that cannot be reproduced by the simulated device with colors that are least noticeable to humans. Each color is associated with one of the colors reproduced by the device. Such correspondence of color points is generally called gamut mapping.

As such a color point matching method, perceptual matching is conventionally known, for example, the method described in Japanese Patent Publication No. 7-48869 and the method disclosed in
No. 288,662 and JP-A-61-28.
No. 8690, for example.

[0010]

In the conventional color point matching method using perceptual matching described above, for example, "a vivid color is vividly expressed while making use of a subtle change in color". Without consideration,
Since the color points are associated with each other so as to mechanically compress the color range, a high-quality (that is, human-preferred) association result is not always obtained.

FIG. 18 shows intersection plane regions Jty and Jsy obtained by intersecting each color solid of the target device and the simulated device with an isohue plane passing through the yellow color point, and passing through each color solid and the purple color point. It is explanatory drawing which respectively shows the crossing surface area | region Jtp obtained by crossing with the same hue surface, Jsp.

In conventional perceptual matching, for example, FIG.
As shown in FIG. 8, on the equi-hue plane passing through the yellow color point, the brightest yellow color point Ty belonging to the intersection plane area Jty of the target device becomes the brightest yellow color point belonging to the intersection plane area Jsy of the simulation device. When the parameter Q1 is selected so as to be associated with the color point Sy of the target device, the most vivid purple color point Tp belonging to the intersection plane area Jtp of the target device on the equi-hue plane passing through the purple color point is determined by the simulation device. Among the color points belonging to the intersection plane area Jsp of
It is associated with the dull purple color point Sk, and as a result of the association, the quality is lowered.

Conversely, on the equi-hue surface passing through the purple color point,
When the parameter Q2 is selected such that the brightest purple color point Tp belonging to the intersection plane area Jtp of the target device is associated with the brightest purple color point Sp belonging to the intersection plane area Jsp of the simulated device, Is the most vivid yellow color point Ty belonging to the intersection plane area Jty of the target device on the equi-hue plane passing through the yellow color point,
Of the color points belonging to the intersection plane area Jsy of the simulated device, the color points are associated with the whitish yellow color point Sw, and in this case, the quality is also reduced as a result of the association.

An object of the present invention is to solve the above-mentioned problems of the prior art and to provide a color point matching technique capable of obtaining a matching result with the highest possible quality.

[0015]

Means for Solving the Problems and Actions and Effects Therefor, to achieve at least a part of the above-mentioned object, a first invention is ^{directed to} a first and a second invention which exist in an L ^* a ^* b ^* color space. A color point association method for associating a first color point belonging to the first color solid with a second color point belonging to the second color solid, for the color solid of (a), L ^* a ^* b
Setting a uniform hue plane that includes the L ^* axis and passes through the first color point in the ^* color space; and (b) a second hue obtained by the intersection of the first color solid and the same hue plane. (C) obtaining a second intersecting plane area, a second intersecting plane area obtained by intersecting the second color solid and the isohue plane, and (c) forming the L ^* axis on the isohue plane. Is parallel to a saturation axis disposed so as to be orthogonal to the first color point, and is parallel to the L ^* axis and the first straight line passing through the first color point. (D) obtaining a first intersection point obtained by intersecting the L ^* axis with the first straight line; and (e) obtaining a second intersection point obtained by intersecting the L ^* axis with the first straight line. 1. the periphery of the intersection plane area;
Determining an intersection obtained by intersecting the first straight line as a second intersection; and (f) intersecting the periphery of the first intersection plane region with the second straight line. And (g) dividing the first line segment having each of the first and second intersection points as an end point into the first color point. The first color point and the second line segment when the first color point internally divides a second line segment having the third and fourth intersections as end points.
And (h) determining the internal division ratio of
Imagining the second color point in the intersection plane area of (i), and (i) on the iso-hue plane, parallel to the saturation axis and passing through the second color point A third straight line, parallel to the L ^* axis, and the second straight line;
Obtaining a fourth straight line passing through the color points of
(J) a step of obtaining a fifth intersection obtained by the intersection of the L ^* axis and the third straight line; and (k) a periphery of the second intersection plane region and the third straight line. A step of obtaining an intersection obtained by intersection as a sixth intersection; and (l) determining two intersections obtained by intersection of the periphery of the second intersection plane region with the fourth straight line. And (m) a third internal division when the second color point internally divides a third line segment having the fifth and sixth intersections as end points. Calculating a ratio and a fourth internal division ratio when the second color point internally divides a fourth line segment having the seventh and eighth intersections as endpoints, respectively, (n ) The third internal ratio is the first internal ratio;
The second color point is rearranged so that the fourth internal division ratio is equal to the second internal division ratio, and the first color point is associated with the second color point. And a step.

As described above, in the first invention, the position of the first color point in the first crossing plane region on the isohue plane having the L ^* axis and the saturation axis orthogonal to each other as coordinate axes is determined. A first internal division ratio when the first color point internally divides a line segment parallel to the saturation axis, and a second internal ratio when the first color point internally divides a line segment parallel to the L ^* axis. It is expressed by the internal division ratio of 2. On the other hand, the position of the imaginary second color point in the second intersecting plane region is defined as a third internal division ratio when the second color point internally divides a line parallel to the saturation axis. , L ^* axis is represented by a fourth internal division ratio when the second color point internally divides the line segment. Then, the second color points are rearranged such that the third internal division ratio is equal to the first internal division ratio and the fourth internal division ratio is equal to the second internal division ratio. One color point is associated. Here, the internal division ratio when a certain line segment is internally divided by a certain internal division point refers to a ratio representing the relative position of the internal division point with respect to the line segment. In addition to the ratio of the length between one end point and the interior division point of the line segment to the length between the other end point and the interior division point, the ratio between the one end point of the line segment and the interior division point And the length of the entire line segment.

Therefore, according to the first aspect, like the conventional perceptual matching, simple color point correspondence such as compression toward an arbitrary point on the L ^* axis or compression in the saturation direction is performed. Since no color points are assigned and color points are associated in accordance with the shape of each intersection plane area, appropriate color point association can be performed for each hue, resulting in a high-quality association result. Can be obtained.

In the color point matching method according to the first invention,
In the step (e), a peripheral edge of the first intersecting plane region;
Instead of the intersection obtained by the intersection of the first straight line and the first straight line, the color point which is parallel to the L ^* axis and is the most color point among the color points existing in the first intersection plane region An intersection obtained by intersecting a first reference straight line passing through a color point with high saturation and the first straight line is obtained as the second intersection, and in the step (k),
The second intersection plane is parallel to the L ^* axis instead of the intersection obtained by intersecting the periphery of the second intersection plane area with the third straight line. An intersection obtained by intersecting a fourth reference straight line passing through the color point having the highest saturation among the color points existing in the region and the third straight line is obtained as the sixth intersection. You may do it.

As described above, instead of using the end point of the line segment parallel to the saturation axis as a point on the periphery of the intersection plane area, it is also possible to use a point on a straight line parallel to the L ^* axis and passing through the highest saturation color point. Since the color points are associated with each other in accordance with the shape of the intersection plane region, appropriate color point association can be performed for each hue, and a high-quality association result can be obtained.

In the color point matching method according to the first invention,
In the step (f), a peripheral edge of the first intersecting plane region;
2 obtained by intersecting with the second straight line
Instead of the two intersections, a color point having the highest lightness among the color points parallel to the saturation axis and present on the L ^* axis in the first intersection plane region is defined as 2nd passing
And a third reference straight line passing through the reference point and the color point having the lowest brightness, and the second straight line, to obtain two intersections obtained by intersecting with each other, as the third and fourth intersections, In the step (l), instead of the two intersections obtained by intersecting the periphery of the second intersection plane region and the fourth straight line, the fourth intersection is parallel to the saturation axis. And a fifth reference straight line passing through a color point having the highest lightness among color points existing on the L ^* axis in the second intersection plane region and a sixth reference line passing through a color point having the lowest lightness.
And the fourth straight line may intersect with each other to obtain two intersections as seventh and eighth intersections.

As described above, instead of using the end point of the line segment parallel to the L ^* axis as a point on the periphery of the intersection plane area, a point on a straight line parallel to the saturation axis and passing through the highest lightness color point and the lowest lightness Color points corresponding to a point on a straight line passing through the color points are also associated with the shape of the intersecting plane area, so that appropriate color point association can be performed for each hue, resulting in high quality correspondence. The result can be obtained.

According to a second aspect of the present invention, for the first and second color solids existing in the L ^* a ^* b ^* color space, the first color point belonging to the first color solid is changed to the second color solid. Second belonging to color solid
A color point associating method for associating with a color point of
(A) In the L ^* a ^* b ^* color space, including the L ^* axis,
Setting an equal hue plane passing through the first color point;
(B) a first intersecting plane area obtained by intersecting the first color solid and the isohue plane, and a second intersecting plane area obtained by intersecting the second color solid and the isohue plane. And (c) the first achromatic color point, which is the color point having the highest lightness, and the lightness point having the highest lightness among the color points existing on the L ^* axis in the first intersection plane area. A first reference point located between the low color point and the second achromatic color point is set, and among the color points existing on the L ^* axis in the second intersection plane area, (D) setting a second reference point located between a third achromatic point, which is a color point having a high lightness, and a fourth achromatic point, which is a color point having the lowest lightness;
A first true maximum chroma color point having the highest saturation among the color points existing in the first intersection plane region, and a first true maximum chroma color point located near the first true maximum chroma color point Is determined as a first maximum saturation color point, and a first line segment connecting the first maximum saturation color point and the first reference point is obtained. And a second true highest chroma color point having the highest chroma among the color points existing in the second intersection plane area, and
One of the second pseudo maximum chroma color points located in the vicinity of the second true maximum chroma color point is set as the second maximum chroma color point, and the second maximum chroma color point is Calculating a second line segment connecting the second reference point and the second reference point; and (g) on the iso-hue plane, in parallel to a saturation axis arranged orthogonal to the L ^* axis. A first reference straight line passing through the first achromatic point and a second reference straight line passing through the second achromatic point; A first selection reference straight line located on the same side as the color point;
^* Are parallel to the axis, and a first straight line passing through the first color point, and obtaining a first intersection point obtained by the intersection, (h) said first segment And the first
And (i) when the first color point internally divides a third line segment having the first and second intersection points as end points. And (j) an achromatic point existing on the first selection reference line among the first and second achromatic points, and a first reference point. And (k) obtaining a first internally dividing point that internally divides a fourth line segment having the respective endpoints at the first internally dividing ratio, and (k) on the same hue plane, The third achromatic point which is parallel to
Of the reference straight line and the fourth reference straight line passing through the fourth achromatic point, a second selection reference straight line located on the same side as the first selection reference straight line with respect to the second line segment Obtaining a third intersection obtained by intersecting a second straight line that is parallel to the L ^* axis and passes through the second maximum chroma color point; (l A) a fifth line segment having, as end points, the achromatic point existing on the second selection reference straight line and the second reference point among the third and fourth achromatic color points. A step of obtaining a second internally dividing point internally divided by the first internally dividing ratio; and (m) a sixth line segment having the second highest chroma color point and the third intersection as end points. Obtaining a third internally dividing point that internally divides by the first internally dividing ratio;
(N) a first half line that starts from the first internally dividing point and passes through the first color point and a periphery of the first intersection plane area intersects a first half line; And (o) a second line when the first color point internally divides a seventh line segment having the first interior division point and the fourth intersection point as end points. A step of calculating an internal dividing ratio; and (p) a second half line starting from the internal dividing point of 2 and passing through the third internal dividing point, and a peripheral edge of the second intersection plane area; Determining a fifth intersection obtained by the intersection of
(Q) obtaining a fifth internally dividing point which internally divides an eighth line segment having the second internally dividing point and the fifth intersection point as end points at the second internally dividing ratio; And associating the first color point with the subdivision point as the second color point.

As described above, in the second invention, the color point having the highest saturation in the first intersection plane area and the reference point existing on the L ^* axis (the true maximum saturation color) And a line segment connecting the first color point and the pseudo-highest saturation color point), the first intersection point area is bisected by the line segment, and the first color point is located in the area where the first color point is located. Is defined as the first internal division ratio when the first color point internally divides the line segment parallel to the L ^* axis, and the line segment connecting the reference point and the color point on the periphery of the intersection area. It is expressed by a second internal division ratio when the first color point is internally divided. On the other hand, the second
, A line segment connecting a reference point on the L ^* axis and a color point having the highest saturation (a true maximum saturation color point or a pseudo maximum saturation color point) in the intersection plane region. Is set, and the second intersection plane area is bisected by the line segment. In the area on the same side as the side where the first color point is located, 2 parallel to the L ^* axis is set.
The two line segments are internally divided at the same internal division ratio as the first internal division ratio, and the intersection between the straight line connecting the two internal division points and the periphery of the second intersection plane area is obtained. An internal dividing point which internally divides a line connecting the dividing point with the same internal dividing ratio as the second internal dividing ratio is found, and the internal dividing point is set as the second color point, and the first color point is associated with the internal dividing point. I have.

Therefore, in the second invention, similarly to the first invention, as in the case of the conventional perceptual matching, compression is performed aiming at an arbitrary point on the L ^* axis or compression is performed in the saturation direction. Since color point matching according to the shape and the like of each intersection area is performed without performing simple color point matching such as performing color matching, appropriate color point matching can be performed for each hue. It is possible to obtain a high-quality matching result.

Further, in the color point associating method according to the second aspect of the present invention, the step (d) includes, among the color points existing in the first intersection plane area, as the first maximum chroma color point. And using the color point with the highest saturation among the color points present in the second intersection plane area as the second highest saturation color point. You may do it.

This is because the processing is easier if the color point having the highest saturation is actually used as the highest saturation color point in the intersecting plane area.

Further, in the color point associating method according to the second aspect of the present invention, (r) a first true maximum saturation color point having the highest saturation among the color points existing in the first intersection plane area. Is set in the vicinity of the first pseudo maximum chroma color point, and the second pseudo color point having the highest chroma among the color points existing in the second intersection plane area is set.
And a step of setting a second pseudo maximum saturation color point located near the true maximum saturation color point of step (d). The method may include a step of using one pseudo maximum chroma color point and using the second pseudo maximum chroma color point as the second maximum chroma color point.

Depending on the shape of the intersecting area, etc., a higher quality matching result can be obtained by using the pseudo-maximum chroma color point as the maximum chroma color point instead of using the true maximum color point. This is because there is a case that is done.

The second using such a pseudo maximum chroma color point
In the color point associating method according to the invention, the step (r)
Is (r-1) parallel to the L ^* axis, and
A third straight line passing through a color point having a saturation lower by a predetermined ratio than the saturation of the first true maximum saturation color point;
Obtaining the sixth and seventh intersections obtained by intersection with the periphery of the intersection plane region of, and imagining a third reference point on a line segment connecting the sixth and seventh intersections; -2) L
^A fourth straight line parallel to the axis and passing through a color point having a saturation lower by a predetermined ratio than the saturation of the second true maximum saturation color point; Eighth and ninth intersections obtained by intersection with the periphery of the intersection plane area are obtained, and a fourth reference point is imagined on a line connecting the eighth and ninth intersections, (r− 3) A ninth line segment whose ends are the tenth and eleventh intersections obtained by intersecting the first and second reference straight lines with the third straight line is referred to as the third reference point. And (r-4) a first internal division ratio obtained by crossing the third and fourth reference straight lines and the fourth linear line.
A tenth line segment having the second and thirteenth intersections as endpoints,
Obtaining a fourth internal division ratio when the fourth reference point is internally divided; and (r-5) a difference between the third internal division ratio and the fourth internal division ratio is minimized. And (r-6) a fifth straight line passing through the first reference point and the rearranged third reference point. , A fourteenth intersection obtained by intersecting a sixth straight line that is parallel to the L ^* axis and that passes through the first true saturation color point.
And (r-7) a seventh straight line passing through the second reference point and the rearranged fourth reference point. A fifteenth intersection obtained by intersecting an eighth straight line that is parallel to the L ^* axis and that passes through the second true maximum chroma color point is obtained. Setting the intersection as the second pseudo maximum chroma color point.

As described above, by setting the pseudo maximum chroma color point, an appropriate association result can be obtained.

According to a third aspect of the present invention, for the first and second color solids existing in the L ^* a ^* b ^* color space, the first color point belonging to the first color solid is converted to the second color solid. Second belonging to color solid
A computer-readable recording medium recording a computer program for associating with the color point of,
In the L ^* a ^* b ^* color space, a function of setting an isohue plane including the L ^* axis and passing through the first color point, and an intersection of the first color solid and the isohue plane A function for obtaining an obtained first intersection plane area, a second intersection plane area obtained by intersecting the second color solid and the isohue plane, and the L ^* axis on the isohue plane. Is parallel to the saturation axis arranged so as to be orthogonal to
The first and the straight line passing through the first color point, is parallel to the L ^* axis, and a second straight line passing through the first color point, and a function of determining each, the L ^* A function for obtaining a first intersection obtained by an intersection of an axis and the first straight line, and an intersection obtained by intersecting the periphery of the first intersection plane region with the first straight line. A function to be determined as an intersection of two, a periphery of the first intersection plane area,
2 obtained by intersecting with the second straight line
A function for obtaining three intersections as third and fourth intersections, and a first function when the first color point internally divides a first line segment having the first and second intersections as end points. Ratio and the third
And a second line segment having the fourth intersection point as an end point,
A second internal division ratio when the color point is internally divided, and the second internal division ratio in the second intersection plane region.
And a third straight line that is parallel to the saturation axis and passes through the second color point on the iso-hue plane and the L ^* axis. A function to determine a fourth straight line that is parallel and passes through the second color point, and a function to determine a fifth intersection obtained by the intersection of the L ^* axis and the third straight line. A function to determine an intersection obtained by intersecting the peripheral edge of the second intersection plane region and the third straight line as a sixth intersection point, a peripheral function of the second intersection plane region, The two intersections obtained by the intersection of the straight line of
And the function obtained as the eighth intersection, and the fifth and sixth functions
A third internal division ratio when the second color point internally divides a third line segment having each of the intersections as end points, and a fourth line having each of the seventh and eighth intersections as an end point And a function for determining a fourth internal division ratio when the second color point internally divides the second internal color point. The third internal division ratio is the first internal division ratio and the fourth internal division ratio. The second internal division ratio is equal to the second internal division ratio.
The gist is that a computer program for causing a computer to realize the function of associating the first color point with the second color point after rearranging the color point is recorded.

As a recording medium, a flexible disk, CD-ROM, magneto-optical disk, IC card,
Various computer-readable media such as a ROM cartridge, a punched card, a printed matter on which a code such as a barcode is printed, an internal storage device (memory such as RAM and ROM) and an external storage device of the computer can be used.

When a computer program recorded on such a recording medium is executed by a computer,
First, on an iso-hue surface having the L ^* axis and the saturation axis orthogonal to each other as coordinate axes, a first internal division when the first color point internally divides a first line segment parallel to the saturation axis. A ratio, and a second internal division ratio when the first color point internally divides a second line segment parallel to the L ^* axis;
Respectively. Next, a third internal division ratio when the virtual second color point internally divides the third line segment parallel to the saturation axis,
And a fourth internal division ratio when the second color point internally divides the fourth line segment parallel to the L ^* axis. Then, the second color points are rearranged such that the third internal division ratio is equal to the first internal division ratio and the fourth internal division ratio is equal to the second internal division ratio. One color point is associated.

Therefore, according to the third aspect, the same effects as those of the first aspect can be obtained.

In a fourth aspect of the present invention, for the first and second color solids existing in the L ^* a ^* b ^* color space, a first color point belonging to the first color solid is set to the first color solid. A computer-readable recording medium recording a computer program for associating with a second color point belonging to two color solids, wherein the L ^* a ^* b ^* color space includes an L ^* axis,
A function of setting an iso-hue plane passing through the first color point, a first intersection plane area obtained by intersection of the first color solid and the iso-hue plane, the second color solid, and the like. A function for respectively obtaining a second intersection plane area obtained by intersection with a hue plane, and a function for obtaining a color point having the highest lightness among color points existing on the L ^* axis in the first intersection plane area. A certain first
And a first reference point located between the achromatic color point and the second achromatic color point, which is the color point having the lowest lightness, is set on the L ^* axis in the second intersection plane area. Among the existing color points, a second reference point located between a third achromatic point, which is the color point with the highest brightness, and a fourth achromatic point, which is the color point with the lowest brightness, is set. A function and a first line segment connecting the first highest saturation color point existing in the first intersection plane area and the first reference point are obtained, and the first line segment is obtained in the second intersection plane area. A function for obtaining a second line segment connecting an existing second highest chroma color point and the second reference point; and a color arranged so as to be orthogonal to the L ^* axis on the iso-hue surface. Of the first reference straight line passing through the first achromatic point and the second reference straight line passing through the second achromatic point, As a boundary a line segment, a first selection reference straight line located on the same side as the first color point, the L ^*
A function for determining a first intersection obtained by intersecting a first straight line that is parallel to an axis and passes through the first color point; And a function for obtaining a second intersection obtained by intersection with a straight line of the first color point when the first color point internally divides a third line segment having the first and second intersections as end points. And an achromatic point existing on the first selection reference straight line and the first reference point among the first and second achromatic color points, as end points. A function of obtaining a first internally dividing point that internally divides a fourth line segment to be divided by the first internally dividing ratio, and on the isohue surface, being parallel to the saturation axis, and Of the third reference straight line passing through the third achromatic point and the fourth reference straight line passing through the fourth achromatic point, the fourth reference straight line is bounded by the second line segment. A second selection reference line positioned on the same side as the selected reference line is parallel to the L ^* axis, and a second straight line passing through the second maximum chroma color point, cross And a function for obtaining a third intersection obtained by performing the above operation, and among the third and fourth achromatic points, an achromatic point existing on the second selection reference straight line, and the second reference point. , And a function for obtaining a second internally dividing point that internally divides a fifth line segment having the end points at the first internally dividing ratio,
A function of obtaining a third internally dividing point that internally divides a sixth line segment having the highest saturation color point and the third intersection as end points at the first internally dividing ratio, A function for obtaining a fourth intersection obtained by intersecting a first half line passing through the first color point with a perimeter of the first intersection plane region, starting from the interior division point A function of calculating a second internal division ratio when the first color point internally divides a seventh line segment having the first internal division point and the fourth intersection point as end points; And a fifth intersection point obtained by intersecting a second half line passing through the third interior division point with the peripheral edge of the second intersection plane area is determined. Function and the second
A fifth internal dividing point which internally divides an eighth line segment having the internal dividing point and the fifth intersection point as end points at the second internal dividing ratio is determined, and the fifth internal dividing point is obtained by The gist is that a computer program for causing a computer to realize the function of associating the first color point with the second color point is recorded.
When the computer program recorded on such a recording medium is executed by the computer, first, in the first intersection plane area, the reference point existing on the L ^* axis and the highest saturation in the intersection plane area are obtained. A first line segment connecting the color point (the true maximum chroma color point or the pseudo maximum chroma color point) is set, and the first intersection plane region is bisected by the first line segment.
A first internal division ratio when the first color point internally divides the third line segment parallel to the L ^* axis in the region where the color point is located;
A second internal division ratio when the first color point internally divides a seventh line segment connecting the reference point and the color point on the periphery of the intersection plane area is determined. On the other hand, even within the second intersection area, L ^*
A second line segment connecting the reference point existing on the axis and the color point having the highest saturation (true highest saturation color point or pseudo maximum saturation color point) in the intersection plane area is set, and the second line segment is set. The second intersection plane area is bisected by the line segment, and the fifth line segment and the sixth line segment parallel to the L ^* axis are divided into the first region in the region on the same side as the side where the first color point is located. , And the intersection between the second half line connecting the two internally dividing points and the periphery of the second intersection plane area is obtained, and the intersection and the fifth line segment are obtained. Finds an internal dividing point that internally divides an eighth line segment connecting the internal dividing point with the internal dividing ratio equal to the second internal dividing ratio, and uses the internal dividing point as a second color point as a first color point. Are associated with each other.

Therefore, according to the fourth aspect, the same effects as those of the second aspect can be obtained.

[0037]

Other Embodiments of the Invention The present invention can also adopt the following other embodiments. A first aspect is an aspect as a program supply device that supplies, via a communication path, a computer program that causes a computer to realize the functions of the respective steps of the above-described invention. In such an embodiment, the above-described color point association method can be realized by placing the program on a server or the like on a network, downloading the necessary program to a computer via a communication path, and executing the program.

[0038]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples. 1 and 2 are flowcharts showing a processing procedure in a color point matching method as a first embodiment of the present invention, and FIG. 3 is a color point for implementing the color point matching method shown in FIGS. FIG. 3 is a block diagram showing an associating device.

The color point associating device shown in FIG. 3 includes a computer main body 20 such as a workstation, a hard disk device 30, an input device 40 such as a keyboard and a mouse for an operator to input instructions, and an image processing device. A display device 50 such as a CRT for displaying, a CD-ROM device 60, and a communication device 7 such as a modem or a network card.
0 is provided.

Of these, the computer body 20 is a CP that executes various processes according to a computer program.
U22, a memory 24 for temporarily storing computer programs and data obtained during the processing, a hard disk device 30, an input device 40, a display device 50, and a CD.
An I / O circuit 26 for exchanging data with the ROM device 60, the communication device 70, and the like.

In the memory 24, which is an internal storage device, a computer program for causing the CPU 22 to realize each processing function in the color association method shown in FIGS. 1 and 2 is stored as the computer program. The CPU 22 implements the above-described processing functions of the computer program by sequentially reading and executing the computer programs stored in the memory 24.

On the other hand, the CD-ROM device 60 has a CD-RO in which the computer program and various data are recorded.
M62 is attached, and the communication device 70 has a network 72
Is connected to the server 80 via the. The server 80 has a function as a program supply device that supplies the computer program to a computer via the network 72.

The computer program stored in the memory 24 is provided in a form recorded on a computer-readable recording medium such as the CD-ROM 62 described above. The computer program recorded on the recording medium is read by a reading device such as the CD-ROM device 60, and is transferred to and stored in the hard disk device 30 as an external storage device. Then, the data is transferred to the memory 24 which is an internal storage device as needed at the time of activation or the like. Alternatively, the read computer program may be directly transferred to the memory 24 without passing through the hard disk device 30.

The computer program may be supplied to the computer from the server 80, which is a program supply device, via the network 72.

In this specification, a computer is
The concept includes a hardware device and an operation system, and means a hardware device that operates under the control of the operation system. In the case where an operation system is unnecessary and a hardware device is operated by an application program alone, the hardware device itself corresponds to a computer. The hardware device includes at least a microprocessor such as a CPU 22 and a reading device such as a CD-ROM device 60 for reading a computer program recorded on a recording medium. The computer program includes a program code for causing such a computer to realize each of the processing functions. Some of the above functions are not application programs,
It may be realized by an operation system.

In this embodiment, the use of a CD-ROM as a "recording medium" for recording a computer program in a computer-readable manner has been described.
Various computer-readable media such as a C card, a ROM cartridge, a punched card, a printed matter on which a code such as a bar code is printed, a computer internal storage device (memory such as RAM and ROM), and an external storage device are used. it can.

Next, the method of associating color points according to the present embodiment will be described with reference to FIGS. As shown in FIG. 1, in the present embodiment, first, a color solid It of the target device and a color solid Is of the simulated device are prepared in the L ^* a ^* b ^* color space (step S20).

FIG. 4 is an explanatory diagram for explaining the same hue plane setting processing shown in step S22 of FIG. L ^* a ^* b ^*
FIG. 4A shows the color solid It of the target device among the color solids prepared in the color space. The color solid It of the target device is a hexahedron having eight vertices. Of the eight vertices, W and K on the L ^* axis are white and black color points, respectively. , M, Y and R, G, B represent cyan, magenta, yellow and red, respectively.
Green and blue color points. On the other hand, the color solid Is of the simulated device also has a different shape from the color solid It of the target device, but forms a hexahedron having eight vertices.

The color solids of the target device and the simulated device can be obtained as follows. First, color data of an arbitrary color is input to each device, and printing for that color is performed by each device. Next, the printed color is measured by a colorimeter to obtain L ^* , a ^* , and b ^* color data of the printed color. Then, based on the obtained L ^* , a ^* , b ^* color data, the color points are plotted in the L ^* a ^* b ^* color space. Thus, by sequentially plotting the color points for various colors in the same manner, a color solid unique to each device is generated in the L ^* a ^* b ^* color space.

The data of the color solid It of the target device and the color solid Is of the simulated device prepared as described above are stored in the hard disk device 30 shown in FIG.

Next, consider a case where an arbitrary color point P belonging to the color solid It of the target device is associated with a color point P 'belonging to the color solid Is of the simulated device. Therefore, in the present embodiment, first, the CPU 22 passes through the color point P with respect to each of the color solids It and Is of the target device and the simulated device stored in the hard disk device as shown in FIG. And L
A color plane ω including the ^* axis is set (step S22). In FIG. 4, me is a direction representing a change in lightness (lightness direction).
, Sa denotes the direction (saturation direction) representing the change in saturation, si
Indicates a direction (hue direction) indicating a change in hue. That is, the above-mentioned color plane ω forms an equal hue plane having the same hue as the color point P.

When the iso-hue plane ω is set as described above, the iso-hue plane ω intersects the color solid It of the target device and the color solid Is of the simulated device. Then, in the present embodiment, next, the CPU 22 determines the intersection plane region Jt obtained by the intersection of the iso-hue plane ω and the color solid It of the target device, and the intersection of the iso-hue plane ω and the color solid Is of the target device. Intersection area Js obtained by
Are obtained (step S24). Figure 4
(B) shows only the intersection plane region Jt (the region indicated by oblique lines) of the target device.

FIG. 5 shows the thus obtained intersection plane region Jt of the target device and the intersection plane region Js of the simulated device on the equal hue plane ω. FIG. 5 is an explanatory diagram showing the intersection plane regions Jt and Js obtained in step S24 of FIG.

Here, since the equal hue plane ω is a plane along the lightness direction me and the saturation sa as is clear from FIG. 3B, the L ^* axis (in other words, , A lightness axis representing a change in lightness) and a saturation axis representing a change in saturation.
It can be represented as a color plane with two coordinate axes. Note that the saturation of a certain color point on the iso-hue surface ω is L ^{* of the} color point ^.
Assuming that the coordinate values in the a ^* b ^* color space are (L, a, b),
Expressed as the square root of a ² + b ² .

Next, in this embodiment, on the iso-hue plane ω, as shown in FIG. 5 (a), the CPU 22 adjusts a straight line ht passing through the color point P in parallel with the saturation axis and an L ^* axis. Parallel and color point P
, And a straight line gt passing through (step S2)
6). Then, an intersection point At between the L ^* axis and the straight line ht and an intersection Bt between the periphery of the intersection plane area Jt of the target device and the straight line ht are obtained (steps S28 and S3).
0), and 2 between the periphery of the intersection plane area Jt and the straight line gt.
The two intersections Ct and Dt are obtained (step S3).
2).

Next, in the present embodiment, the CPU 22 obtains the length m of the line segment AtP and the line segment AtBt according to the equation (1) (step S34).

[0057]

(Equation 1)

Further, the CPU 22 obtains the length ratio n of the line segment CtP and the line segment CtDt according to the equation (2) (step S34).

[0059]

(Equation 2)

Next, in this embodiment, as shown in FIG.
In the intersecting plane area Js of the simulated device, a color point P ′ to be associated with the color point P is temporarily assumed (step S36), and the CPU 22 performs the processing shown in FIG. Thus, a straight line hs parallel to the saturation axis and passing through the assumed color point P 'and a straight line gs parallel to the L ^* axis and passing through the color point P' are obtained (step S38). Then, an intersection As between the L ^* axis and the straight line hs and an intersection B between the periphery of the intersection plane Js of the simulation device and the straight line hs
s are obtained (steps S40 and S42), and two intersections Cs and Ds between the periphery of the intersecting plane area Js and the straight line gs are obtained (step S44).

Next, in the present embodiment, the CPU 22 obtains the length ratio m 'of the line segment AsP' and the line segment AsBs according to the equation (3) (step S46).

[0062]

(Equation 3)

Further, the CPU 22 obtains the length ratio n 'of the line segment CsP' and the line segment CsDs according to the equation (4) (step S46).

[0064]

(Equation 4)

Finally, in this embodiment, the CPU 22 uses the ratios obtained in steps S34 and S46 to set the ratio m 'equal to the ratio m (m' = m) and to set the ratio n 'to the ratio n. The color points P 'assumed in step S36 are rearranged so as to be equal (n' = n). Then, the color point P is associated with the color point P ′.

In this manner, for each color point existing in the cross-plane area Jt of the target device, the color point to which the color point is associated is derived, so that the color point existing in the cross-plane area Jt of the target device on the uniform hue plane ω is obtained. All the color points to be processed are the intersection plane area Js of the simulated device.
Is associated with any of the color points that exist within.

Then, after the association of the color points on the iso-hue plane ω is completed, the color points on the other iso-hue planes are similarly associated with each other. I do. Then, by associating color points with respect to all equal hue planes in the L ^* a ^* b ^* color space,
All the color points belonging to the color solid It of the target device are associated with any of the color points belonging to the color solid Is of the simulation device.

When the color points belonging to the color solid It of the target device and the color points belonging to the color solid Is of the simulated device have been associated with each other as described above, the correspondence is determined, for example, for color conversion. It is stored in a lookup table or the like. When the image data (color data) to be given to the target device is given to the simulation device, the image data is once input to the color conversion look-up table. Color conversion, and then give it to the simulated device.

As described above, in the present embodiment, the position of the color point P in the cross-plane area Jt on the iso-hue plane having the L ^* axis and the saturation axis as coordinate axes is determined by the line parallel to the saturation axis. The internal division ratio m when the color point P internally divides the component AtBt and the internal division ratio n when the color point P internally divides the line segment CtDt parallel to the L ^* axis, and the virtual color point The position of P ′ in the intersecting plane region Js is defined as the internal division ratio m ′ when the color point P ′ internally divides the line segment AsBs parallel to the saturation axis, and the line segment CsDs parallel to the L ^* axis. It is represented by an internal division ratio n ′ when the color point P ′ is internally divided. The color point P ′ to be associated is rearranged so that the respective ratios become equal (m ′ = m, n ′ = n).

Therefore, according to the present embodiment, as in the case of conventional perceptual matching, simple color point correspondence such as compression toward an arbitrary point on the L ^* axis or compression in the saturation direction is performed. Are performed, and color points are associated according to the shape of each intersecting plane region Jt, Js of the target device and the simulated device. Therefore, accurate color point association is performed for each hue. Therefore, a high-quality matching result can be obtained.

Next, a second embodiment of the present invention will be described. FIGS. 6 and 7 are flowcharts showing the processing procedure in the color point association method according to the second embodiment of the present invention. In the present embodiment, as shown in FIG.
The processing from 50 to S58 is performed in step S shown in FIG.
This is the same as the processing from 20 to S28. Therefore, the processing after step S60 will be described. In addition, as an apparatus for implementing the color point association method of the present embodiment,
Since it is the same as the color point associating device shown in FIG. 3, its description is omitted. However, the memory 24 which is an internal storage device
Stores a computer program for causing the CPU 22 to realize each processing function in the color association method shown in FIGS. 6 and 7 as a computer program. The CPU 22 implements the above-described processing functions of the computer program by sequentially reading and executing the computer programs stored in the memory 24.

FIG. 8 is an explanatory diagram for explaining a color point associating method according to the second embodiment. In the present embodiment, as shown in FIG. 8, instead of using the end point of the line segment parallel to the saturation axis as a point on the periphery of the intersection plane area, the end point of the line is parallel to the L ^* axis and passes through the highest saturation color point Vt. It is a point on a straight line. Therefore, step S
After the processing of step S58, the CPU 22 obtains a straight line qt parallel to the L ^* axis and passing through the maximum chroma color point Vt on the iso-hue plane ω (step S6).
0). In this embodiment, the highest chroma color point Vt refers to a color point having the highest chroma among the color points existing in the intersection plane area Jt of the target device.

Next, the intersection Bvt of the straight line qt and the straight line ht
(Step S62), the line segment AtP and the line segment AtBv
The length ratio of t is set to m (step S66). The intersections Ct and Dt and the ratio n are the same as in the first embodiment (steps S64 and S66).

Next, in this embodiment, as shown in FIG. 7, the processing from steps S68 to S72 is the same as the processing from steps S36 to S40 shown in FIG. Therefore, the processing after step S74 will be described. Therefore, first, the CPU 22 obtains a straight line qs parallel to the L ^* axis and passing through the maximum chroma color point Vs on the iso-hue surface ω as shown in FIG. 8B (step S74).
In this embodiment, the highest saturation color point Vs refers to the color point having the highest saturation among the color points existing in the intersection plane region Js of the simulation device.

Next, the intersection Bvs between the straight line qs and the straight line hs
(Step S76), the line segment AsP 'and the line segment AsB
The ratio of the length of vs is set to m '(step S80). At this time, the intersections Cs and Ds and the ratio n ′ are the same as in the first embodiment (steps S78 and S80).

The process of rearranging the color point P '(step S82) is the same as the process of step S48 in the first embodiment.

Next, a third embodiment of the present invention will be described. FIGS. 9 and 10 are flowcharts showing the processing procedure in the color point association method according to the third embodiment of the present invention. In the present embodiment, as shown in FIG. 9, the processing from steps S90 to S100 is the same as the processing from steps S20 to S30 shown in FIG. Therefore,
The processing after step S100 will be described. In addition,
An apparatus for performing the color point association method of the present embodiment also includes:
Since it is the same as the color point associating device shown in FIG. 3, its description is omitted. However, the memory 24 which is an internal storage device
9 and 10 as computer programs
Each processing function in the color association method shown in FIG.
A computer program for realizing the above is stored. The CPU 22 implements the above-described processing functions of the computer program by sequentially reading and executing the computer programs stored in the memory 24.

FIG. 11 is an explanatory diagram for explaining a color point associating method according to the third embodiment. In this embodiment, FIG.
, Instead of using the end point of a line segment parallel to the L ^* axis as a point on the periphery of the intersection plane area, a straight line parallel to the saturation axis and passing through the highest lightness color point Wt or the lowest lightness color point Kt The point is. Therefore, after ending the processing of step S100, the CPU 22 sets the
As shown in (a), the highest lightness color point Wt parallel to the saturation axis
, And a straight line st that is also parallel to the saturation axis and passes through the lowest lightness color point Kt (step S).
102). Here, the highest lightness color point Wt refers to the color point having the highest lightness among the color points existing in the intersection plane Jt of the target device, and the lowest lightness color point Kt is the color point having the lowest lightness. Say

Next, the intersection Cwt between the straight line rt and the straight line gt
, And the intersections Dkt of the straight line st and the straight line gt are obtained (step 104), and the line segments CwtP and CwtDkt are obtained.
Is set to n (step S106). In the present embodiment, the ratio m is the same as in the first embodiment (step S106).

Next, in this embodiment, as shown in FIG.
The processing from steps S108 to S114 is the same as the processing from steps S36 to S42 shown in FIG. Therefore, the processing after step S116 will be described. Therefore, first, as shown in FIG. 11B, the CPU 22 determines, on the iso-hue surface ω, a straight line rs parallel to the saturation axis and passing through the maximum brightness color point Ws, and a minimum brightness parallel to the saturation axis. A straight line ss passing through the color point Ks is obtained (step S116). Here, the highest lightness color point Ws refers to the color point having the highest lightness among the color points existing in the intersection plane Js of the simulation device, and the lowest lightness color point Ks is the color having the lowest lightness. Say the point.

Next, the intersection Cws of the straight line rs and the straight line gs
, And the intersection Dks between the straight line ss and the straight line gs is obtained (step 118), and the line segment CwsP ′ and the line segment CwsDk are obtained.
The length ratio of s is set to n ′ (step S120). In this embodiment, the ratio m is the same as in the first embodiment (Step S120).

The process of rearranging the color point P '(step S122) is the same as the process of step S48 in the first embodiment.

As described above, in the second and third embodiments, instead of using the end point of the line segment parallel to the saturation axis or the L ^* axis as a point on the periphery of the intersection plane area, the L ^* axis is used. A point on a straight line that passes in parallel and passes through the highest chroma color point, or a straight line that passes in parallel with the chroma axis and passes through the highest lightness color point or the lowest lightness color point, and these line segments are internally divided by the color points P and P ′. The color point p 'is rearranged based on the internal division ratio at that time.

Therefore, also in this embodiment, as in the first embodiment, simple color point correspondence is not performed, and it is determined according to the shape of the intersection plane regions Jt and Js of the target device and the simulated device. Since the associated color points are associated with each other, a high-quality association result can be obtained.

Next, a fourth embodiment of the present invention will be described. FIGS. 12, 13 and 14 are flowcharts showing processing procedures in the color point association method according to the fourth embodiment of the present invention. In the present embodiment, as shown in FIG. 12, the processing from steps S130 to S134 is performed as shown in FIG.
Are the same as the processes from steps S20 to S24 shown in FIG. Therefore, the processing after step S136 will be described. Note that an apparatus for implementing the color point association method of the present embodiment is the same as the color point association apparatus shown in FIG. 3, and a description thereof will be omitted. However, in the memory 24 which is an internal storage device, as a computer program,
A computer program for causing the CPU 22 to realize each processing function in the color association method shown in FIGS. 12, 13, and 14 is stored. CPU 22
Implements the processing functions of the computer program by sequentially reading and executing the computer programs stored in the memory 24.

FIG. 15 is an explanatory diagram for explaining a color point associating method according to the fourth embodiment. In the present embodiment, after the processing of step S124 is completed, the CPU 22 sets the reference point Mt on the L ^* axis for the intersection plane Jt of the target device as shown in FIG. )
And a reference point Ms for the intersecting plane region Js of the simulated device are set (step S136). At this time, as the reference points Mt and Ms, for example, in each of the intersection plane regions Jt and Js, the middle points of the line segments WtKt and WsKt connecting the highest lightness color points Wt and Ws and the lowest lightness color points Kt and Ks, respectively. Set.

Next, in this embodiment, the CPU 22 obtains a line segment MtVt connecting the reference point Mt and the maximum chroma color point Vt in the intersection plane area Jt, and also determines the reference point Ms in the intersection plane area Js. A line segment M connecting the highest saturation color point Vs
sVs is obtained (step S138).

Subsequently, the CPU 22 sets the color point P to the line segment MtVt in the intersection plane area Jt of the target device.
It is determined whether or not there is a lower region (that is, a region with low lightness) with (step S140). As a result of the determination, if the color point P exists in the lower region, the process proceeds to step S142 shown in FIG. 13, and if it exists in the upper region (region with high brightness), the process proceeds to step S164 shown in FIG.

Now, assuming that the color point P exists in an area below the line segment MtVt as shown in FIG. 15A, the CPU 22 executes a straight line parallel to the saturation axis and passing through the minimum lightness color point Kt. An intersection Ut of the straight line gt passing through the color point P parallel to st and the L ^* axis is determined (step S142), and an intersection Ht of the line segment MtVt and the straight line gt is determined (step S142).
144).

Then, the CPU 22 obtains the ratio e of the length of the line segment PUt and the line segment HtUt according to the equation (5) (step S146).

[0091]

(Equation 5)

Next, the CPU 22 calculates the line segment Mt on the L ^* axis.
An internal dividing point Q that internally divides Kt by the ratio e obtained in step S146 is obtained (step S148).

Subsequently, as shown in FIG. 15B, the CPU 22 executes a straight line ss parallel to the saturation axis and passing through the lowest lightness color point Ks and a straight line parallel to the L ^* axis and passing through the highest saturation color point Vs. tt
Is determined (step S150). Then, an internal division point Q ′ which internally divides the line segment MsKs on the L ^* axis by the ratio e obtained in step S146 is obtained (step S152), and the line segment VsKvs on the straight line tt is also internally obtained by the ratio e. The subdivision point Z to be divided is obtained (step S15)
4).

Next, in the present embodiment, the CPU 22
As shown in FIG. 5A, an intersection T between the half line ut starting from the interior division point Q and passing through the color point P and the periphery of the intersection plane region Jt of the target device is obtained (step S15).
6) and, according to equation (6), the line segment QP and the line segment QT
Is determined (step S158).

[0095]

(Equation 6)

On the other hand, similarly, on the simulated device side, the CPU 22 obtains the intersection S between the half line us starting from the interior division point Q 'and passing through the interior division point Z and the intersection plane area Js (step S1). S160). Then, the line segment Q'S is
An internal dividing point P 'that is internally divided by the ratio f obtained in step S158 is obtained, and the color point P is associated with the internal dividing point P' (step S162).

The CPU 22 determines in step S140 shown in FIG. 12 that the color point P exists in the area above the line segment MtVt, and determines in step S140 shown in FIG.
When the process proceeds to 164, the processing procedure is as follows.

That is, the CPU 22 determines that not the straight line st passing through the lowest lightness color point Kt but the straight line r passing through the highest lightness color point Wt
An intersection Xt between t and a straight line gt passing through the color point P is determined (step S164), and the line segment PHt and the line segment X are calculated according to the equation (7).
The length ratio e of tUt is determined (step S168).

[0099]

(Equation 7)

Next, the CPU 22 calculates the line segment Wt on the L ^* axis.
An internal dividing point Q that internally divides Mt by the ratio e obtained in step S168 is obtained (step S170).

Subsequently, the CPU 22 sets the minimum lightness color point Ks
Is obtained, instead of the straight line ss passing through, the intersection Wvs of the maximum lightness color point Ws and the straight line tt passing through the maximum chroma color point Vs (step S172). Then, the line segment WsMs on the L ^* axis is
An internal dividing point Q 'which internally divides by the ratio e obtained in step S168 is obtained (step S174), and an internal dividing point Z which similarly divides the line segment WvsVs on the straight line tt by the ratio e is obtained (step S176). .

When the processing in step S176 is completed, the flow advances to the processing in step S156 shown in FIG.

As described above, in the present embodiment, in the intersecting plane region Jt of the target device, the line segment M connecting the reference point Mt existing on the L ^* axis and the maximum chroma color point Vt is obtained.
tVt is set, and the intersecting plane region Jt is bisected by the line segment. Then, in the region where the color point P exists,
A line connecting the position of the color point P to an internal division ratio e when the color point P internally divides a line segment parallel to the L ^* axis, and a reference point Mt and a color point T on the periphery of the intersection plane area Jt. Is expressed by an internal division ratio f when the color point P is internally divided. On the other hand, a line segment MsVs connecting the reference point Ms existing on the L ^* axis and the maximum chroma color point Vs is set in the cross-plane region Js of the simulation device, and the cross-plane region Js is defined by the line segment. Bisect. And the color point P
In the area on the same side as the side on which the line exists, the line segment parallel to the L ^* axis is internally divided at the same internal division ratio as the internal division ratio e, and the reference point M
A line segment connecting s and a color point S on the periphery of the intersection area Js is found as an internal dividing point which is internally divided at the same internal dividing ratio as the internal dividing ratio f. P is made to correspond.

Therefore, in this embodiment, as in the case of the first embodiment, compression is performed aiming at an arbitrary point on the L ^* axis or compression is performed in the saturation direction, as in the case of the conventional perceptual matching. Since color point matching according to the shape and the like of each intersection area is performed without performing simple color point matching such as performing color matching, appropriate color point matching can be performed for each hue. It is possible to obtain a high-quality matching result.

According to the present embodiment, the calculation result does not easily converge and the calculation does not take a long time, and the color point P ′ to which the color point P is associated can be obtained at an early stage. it can.

In the present embodiment, the highest saturation color point Vt, Vs is defined as the color point with the highest saturation in each cross-plane area Jt, Js (hereinafter, the true maximum saturation color point). ) Was used, but a pseudo maximum chroma color point set as follows may be used.

FIG. 16 is a flowchart showing a processing procedure for setting the pseudo maximum chroma color point, and FIG. 17 is an explanatory diagram for explaining the pseudo maximum chroma color point setting processing shown in FIG.

The pseudo-maximum-saturation color point setting process shown in FIG.
This is performed during a period from 134 to step S138.

In the setting process shown in FIG.
22 is parallel to the L ^* axis, as shown in FIG.
Intersections α and β between a straight line vt passing through a color point having a saturation that is lower than the saturation of the true maximum saturation color point Vt by a specified ratio and the periphery of the intersection plane area Jt of the target device are determined. A reference point Nt is temporarily assumed on the connected line segment αβ (step S180). That is, the above-mentioned line segment αβ is a lightness range that can be expressed when the achromatic color approaches the achromatic color by a specified ratio from the saturation of the true maximum saturation color point Vt, and within this lightness range, the reference point Nt is virtually set. I do.

Similarly, the CPU 22 also operates on the simulated device side as shown in FIG.
^* The intersection points α ′ and β ′ between the straight line vs that passes through a color point that is parallel to the axis and has a saturation that is lower than the saturation of the true maximum saturation color point Vs by a specified ratio and the periphery of the intersection area Js Then, a reference point Ns is temporarily assumed on a line segment α′β ′ connecting these intersections (step S182). Also in this case, the line segment α'β '
Is a lightness range that can be expressed when approaching an achromatic color by a specified ratio from the saturation of the true maximum saturation color point Vs. In this lightness range, the reference point Ns is imagined.

Next, the CPU 22 determines, for the target device side, the intersection Et, of the straight line rt, st and the straight line vt,
A length ratio i between a line segment EtYt connecting Yt and a line segment NtYt connecting the reference point Nt and the intersection Yt is obtained according to the equation (8) (step S184).

[0112]

(Equation 8)

Similarly, on the simulated device side, the CPU 22 calculates a line segment EsYs connecting the intersection points Es and Ys between the straight lines rs and ss and the straight line vs and a line segment NsYs connecting the reference point Ns and the intersection point Ys. The length ratio i ′ is calculated by equation (9).
(Step S186).

[0114]

(Equation 9)

Next, the CPU 22 determines in step S184,
The reference points Nt and Ns are rearranged within the above-described lightness range so that the absolute value | i−i ′ | of the difference between the ratios i and i ′ obtained in 186 is minimized (step S18).
8).

Thereafter, the CPU 22 sets the intersection of the straight line ct passing through the reference points Q and Nt and the straight line dt passing through the true maximum saturation color point Vt as the pseudo maximum saturation color point Vt '(step S190). The intersection of the straight line cs passing through the reference point Q 'and Ns and the straight line ds passing through the true maximum chroma color point Vs is set as the pseudo maximum chroma color point Vs' (step S192).

The pseudo maximum chroma color point V thus set
By using t ′ and Vs ′ as the maximum saturation color points instead of the true maximum saturation color points Vt and Vs, gradation and the like can be more appropriately associated with each other, and the association result is less likely to cause problems. Become.

The present invention is not limited to the examples and embodiments described above, but can be implemented in various modes without departing from the scope of the invention.

[Brief description of the drawings]

FIG. 1 is a flowchart illustrating a first half of a processing procedure in a color point association method according to a first embodiment of the present invention.

FIG. 2 is a flowchart illustrating the latter half of the processing procedure in the color point association method according to the first embodiment of the present invention.

FIG. 3 is a block diagram showing a color point associating device for implementing the color point associating method shown in FIGS. 1 and 2;

FIG. 4 is an explanatory diagram for explaining an equal hue plane setting process shown in step S22 of FIG. 1;

FIG. 5 is an explanatory diagram showing intersection plane areas Jt and Js obtained in step S24 of FIG. 1;

FIG. 6 is a flowchart illustrating a first half of a processing procedure in a color point association method according to a second embodiment of the present invention.

FIG. 7 is a flowchart illustrating a latter half of a processing procedure in a color point association method according to a second embodiment of the present invention.

FIG. 8 is an explanatory diagram illustrating a color point association method according to a second embodiment.

FIG. 9 is a flowchart illustrating a first half of a processing procedure in a color point association method according to a third embodiment of the present invention.

FIG. 10 is a flowchart illustrating a latter half of a processing procedure in a color point association method according to a third embodiment of the present invention.

FIG. 11 is an explanatory diagram for describing a color point association method according to a third embodiment.

FIG. 12 is a flowchart illustrating a first half of a processing procedure in a color point association method according to a fourth embodiment of the present invention.

FIG. 13 is a flowchart illustrating a latter half of a processing procedure in a color point association method according to a fourth embodiment of the present invention.

FIG. 14 is a flowchart illustrating a part of a processing procedure in a color point association method according to a fourth embodiment of the present invention.

FIG. 15 is an explanatory diagram for describing a color point association method according to a fourth embodiment.

FIG. 16 is a flowchart illustrating a processing procedure for setting a pseudo maximum chroma color point.

FIG. 17 is an explanatory diagram for describing the pseudo-maximum chroma color point setting process shown in FIG. 16;

FIG. 18 is a cross-plane area Jty, Jsy obtained by intersecting each color solid of the target device and the simulated device with an equal hue plane passing through a yellow color point, and an equal hue passing through each color solid and a purple color point. It is explanatory drawing which shows the crossing surface area | region Jtp obtained by crossing a surface, Jsp, respectively.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 20 ... Computer main body 22 ... CPU 24 ... Memory 26 ... I / O circuit 30 ... Hard disk device 40 ... Input device 50 ... Display device 60 ... CD-ROM device 62 ... CD-ROM 70 ... Communication device 72 ... Network 80 ... Server Is ... Color solid of the simulated device It ... Color solid of the target device Js ... Intersection area of the target device Jt ... Intersection area of the simulation device Ks, Kt ... Lowest brightness color point Vs' ... Pseudo maximum saturation color point Vs ... True maximum chroma color point Vt ': Pseudo maximum chroma color point Vt: True maximum chroma color point Ws, Wt: Highest brightness color point ω: Equal hue plane

Claims (9)

[Claims] 1. A method according to claim 1, wherein the first and second color solids existing in the L ^* a ^* b ^* color space are the first and second color solids belonging to the first color solid.
A color point corresponding to the second color solid belonging to the second color solid, wherein: (a) in the L ^* a ^* b ^* color space, the L ^* axis is Including
Setting a uniform hue plane passing through the first color point; and (b) a first intersection plane area obtained by intersecting the first color solid and the uniform hue plane and the second color solid. And a second intersecting plane area obtained by intersecting with the iso-hue plane. (C) On the iso-hue plane, a saturation axis is arranged to be orthogonal to the L ^* axis. A first straight line that is parallel to the first color point and passes through the first color point, and a second straight line that is parallel to the L ^* axis and passes through the first color point. (D) obtaining a first intersection point obtained by intersecting the L ^* axis and the first straight line; and (e) a peripheral edge of the first intersection plane region; Obtaining an intersection obtained by intersecting with the straight line as a second intersection; (f) the first intersection And the peripheral edge of Samen region, and the second straight line, the two intersections obtained by crosses third
And (g) a first internal division ratio when the first color point internally divides a first line segment having the first and second intersections as end points. When,
(H) calculating a second internal division ratio when the first color point internally divides a second line segment having the third and fourth intersections as end points; (2) imagining the second color point in the intersection plane region of (2), and (i) setting the second color point parallel to the saturation axis on the iso-hue plane. A third straight line passing through,
Determining a fourth straight line that is parallel to the L ^* axis and passes through the second color point, respectively, (j) by intersecting the L ^* axis with the third straight line Obtaining a fifth intersection obtained; and (k) obtaining an intersection obtained by intersecting the periphery of the second intersection plane region with the third straight line as a sixth intersection. (1) Two intersections obtained by the intersection of the periphery of the second intersection plane region and the fourth straight line are defined as a seventh intersection.
And (m) a third internal division ratio when the second color point internally divides a third line segment having the fifth and sixth intersections as end points. When,
Obtaining a fourth internal division ratio when the second color point internally divides a fourth line segment having the seventh and eighth intersections as end points, respectively; After rearranging the second color points such that the internal ratio of 3 is equal to the first internal ratio and the fourth internal ratio is equal to the second internal ratio, Associating the first color point with the second color point. 2. The color point associating method according to claim 1, wherein, in the step (e), a periphery of the first intersection plane region is
Instead of the intersection obtained by the intersection of the first straight line and the first straight line, the color point which is parallel to the L ^* axis and is the most color point among the color points existing in the first intersection plane region An intersection obtained by intersecting a first reference straight line passing through a color point with high saturation and the first straight line is obtained as the second intersection, and in the step (k), The periphery of the intersection plane area of No. 2;
In place of the intersection obtained by the intersection of the third straight line and the third straight line, the most color point among the color points parallel to the L ^* axis and existing in the second intersection plane region A color point associating method, wherein an intersection obtained by intersecting a fourth reference straight line passing through a color point with high saturation and the third straight line is obtained as the sixth intersection. 3. The color point associating method according to claim 1, wherein in the step (f), a periphery of the first intersection plane region is
2 obtained by intersecting with the second straight line
Instead of the two intersections, a color point having the highest lightness among the color points parallel to the saturation axis and present on the L ^* axis in the first intersection plane region is defined as 2nd passing
And a third reference straight line passing through the reference point and the color point having the lowest brightness, and the second straight line, to obtain two intersections obtained by intersecting with each other, as the third and fourth intersections, In the step (l), a peripheral edge of the second intersecting plane region;
2 obtained by intersecting with the fourth straight line
Instead of the two intersection points, a color point having the highest lightness among the color points existing on the L ^* axis in the second intersection plane area, which is parallel to the saturation axis, 5th passing
And a sixth reference straight line passing through the reference straight line and the color point having the lowest brightness and the fourth straight line, and two intersections obtained by intersecting the fourth straight line are obtained as seventh and eighth intersections. Color point associating method. 4. The first and second color solids existing in the L ^* a ^* b ^* color space are defined by the first and second color solids belonging to the first color solid.
A color point corresponding to the second color solid belonging to the second color solid, wherein: (a) in the L ^* a ^* b ^* color space, the L ^* axis is Including
Setting a uniform hue plane passing through the first color point; and (b) a first intersection plane area obtained by intersecting the first color solid and the uniform hue plane and the second color solid. And a second intersecting plane area obtained by intersecting with the same hue plane. (C) Of the color points present on the L ^* axis in the first intersecting plane area, Setting a first reference point located between a first achromatic color point which is a color point having a high lightness and a second achromatic color point which is a color point having a lowest lightness; Among the color points present on the L ^* axis in the area, the position is located between the third achromatic point, which is the color point having the highest brightness, and the fourth achromatic color point, which is the color point having the lowest brightness. Setting a second reference point to perform, and (d) a first highest chroma color point existing in the first intersection plane region and the first reference point Calculating a first line segment connecting the second highest saturation color point existing in the second intersection plane area and the second reference point; and (G) a first reference straight line, which is parallel to a saturation axis arranged to be orthogonal to the L ^* axis and passes through the first achromatic point, on the isohue plane; A second selection straight line passing through a second achromatic point, a first selection reference straight line located on the same side as the first color point with respect to the first line segment, and the L ^* axis Determining a first intersection obtained by intersecting a first straight line that is parallel to the first color point and passes through the first color point; and (h) determining the first line segment and the first line segment. A step of obtaining a second intersection obtained by intersection with the first straight line; and (i) a third line having the first and second intersections as end points. Calculating a first internal division ratio when the first color point is internally divided; and (j) present on the first selection reference straight line among the first and second achromatic color points. (K) obtaining a first internally dividing point that internally divides a fourth line segment having the achromatic color point and the first reference point as endpoints at the first internally dividing ratio. On the equi-hue surface, a third reference straight line parallel to the saturation axis and passing through the third achromatic point and a fourth reference straight line passing through the fourth achromatic point And a second selection reference straight line located on the same side as the first selection reference straight line with respect to the second line segment, and the L ^*
Determining a third intersection obtained by intersecting a second straight line that is parallel to the axis and passes through the second maximum chroma color point; (l) the third and the third Among the fourth achromatic points, a fifth line segment having endpoints of the achromatic point existing on the second selection reference straight line and the second reference point is the first internal segment. Determining a second internally dividing point internally divided by a ratio; and (m) forming a sixth line segment having the second highest chroma color point and the third intersection as end points, respectively. A step of obtaining a third internally dividing point that is internally divided at an internally dividing ratio; (n) a first half line that starts from the first internally dividing point and passes through the first color point; Obtaining a fourth intersection obtained by intersecting the periphery of the first intersection plane region; and (o) a seventh intersection having the first interior division point and the fourth intersection respectively as end points. A step of calculating a second internal division ratio when the first color point internally divides the line segment; and (p) starting from the second internal division point and passing through the third internal division point. A step of obtaining a fifth intersection obtained by intersecting a second half line and the periphery of the second intersection plane region; and (q) the second intersection point and the fifth intersection. Are obtained by dividing the eighth line segment having the respective end points with the second internally dividing ratio, and the fifth internally divided point is defined as the second color point by the first internally divided point. Associating color points; and a color point association method. 5. The color point associating method according to claim 4, wherein the step (d) includes the step of determining a color point existing in the first intersection plane area as the first maximum chroma color point. Using the color point with the highest saturation among them, and using the color point with the highest saturation among the color points present in the second intersection plane area as the second highest saturation color point. Color point correspondence method to be provided. 6. The color point associating method according to claim 4, wherein: (r) a first true maximum saturation color having the highest saturation among the color points existing in the first intersection plane region. A first pseudo-highest-saturation color point located near the point is set, and a second true highest-saturation color point having the highest saturation among the color points existing in the second intersection plane region is set. The method further comprises the step of setting a second pseudo maximum chroma color point located in the vicinity, and the step (d) includes the step of setting the first pseudo maximum chroma point as the first maximum chroma color point. A color point associating method, comprising: using a set color point and using the set second pseudo highest chroma color point as the second highest chroma color point. 7. The color point associating method according to claim 6, wherein the step (r) comprises: (r-1) parallel to the L ^* axis, and the first true maximum color. Sixth and seventh points obtained by intersection of a third straight line passing through a color point having a saturation lower by a predetermined ratio than the saturation of the degree color point and the periphery of the first intersection plane region. Determining a point of intersection and imagining a third reference point on a line segment connecting the sixth and seventh points of intersection; and (r-2) parallel to the L ^* axis, and The fourth straight line passing through a color point having a saturation lower by a predetermined ratio than the true maximum saturation color point has and a peripheral edge of the second intersection plane area. And obtaining a ninth intersection, and imagining a fourth reference point on a line connecting the eighth and ninth intersections; and (r-3) the first and second references. Tenth and eleventh and the the line third linear obtained by crossing
(R-4) obtaining a third internal division ratio when the third reference point internally divides a ninth line segment having the intersection point of each of the ninth line segment as an end point; Twelfth and thirteenth obtained by intersection of a straight line and the fourth straight line
Calculating a fourth internal division ratio when the fourth reference point internally divides a tenth line segment having the intersection point of each as an end point; and (r-5) the third internal division ratio A step of rearranging the third and fourth reference points so that a difference from the fourth internal division ratio is minimized; and (r-6) rearranged with the first reference point. A fifth straight line passing through the third reference point intersects with a sixth straight line that is parallel to the L ^* axis and passes through the first true chroma color point. Obtaining a fourteenth intersection obtained by the above, and setting the fourteenth intersection as the first pseudo maximum chroma color point; and (r-7) the rearranged with the second reference point. A seventh straight line passing through a fourth reference point intersects with an eighth straight line that is parallel to the L ^* axis and passes through the second true saturation color point. Obtaining a fifteenth intersection obtained as a result, and setting the fifteenth intersection as the second pseudo maximum chroma color point. 8. The first and second color solids existing in the L ^* a ^* b ^* color space are defined by the first and second color solids belonging to the first color solid.
A computer program for recording a computer program for associating the color point of the second color point with the second color point belonging to the second color solid, wherein in the L ^* a ^* b ^* color space, A function of setting an iso-hue plane including the ^* axis and passing through the first color point; a first intersection plane area obtained by intersection of the first color solid and the iso-hue plane; A function for respectively obtaining a second intersecting plane area obtained by intersecting the color solid and the isohue plane; and a function of calculating a saturation axis arranged orthogonal to the L ^* axis on the isohue plane. Parallel to each other and the first
A first straight line passing through the color point is parallel to the L ^* axis, and a second straight line passing through the first color point, and a function of determining each, and the L ^* axis above A function of obtaining a first intersection obtained by intersection with a first straight line; and an intersection obtained by intersection of the periphery of the first intersection plane area with the first straight line is referred to as a second intersection. And a function to determine two intersections obtained by the intersection of the periphery of the first intersection plane area and the second straight line as third and fourth intersections; A first internal division ratio when the first color point internally divides a first line segment each having a second intersection as an end point, and a second internal division ratio where each of the third and fourth intersections is an end point. A second internal division ratio when the first color point internally divides the line segment, and a second intersection A function of imagining the second color point in the region; and a third straight line parallel to the saturation axis and passing through the second color point on the iso-hue plane; Said L
^A fourth straight line that is parallel to the ^* axis and passes through the second color point, and a fifth straight line obtained by the intersection of the L ^* axis and the third straight line. A function for obtaining an intersection, a function for obtaining, as a sixth intersection, an intersection obtained by intersecting the periphery of the second intersection plane area and the third straight line, A function for obtaining, as seventh and eighth intersections, two intersections obtained by intersecting a peripheral edge and the fourth straight line; and a third line having the fifth and sixth intersections as end points. A third internal division ratio when the second color point internally divides the second color point, and a fourth line segment having each of the seventh and eighth intersections as an end point. And a function for respectively obtaining a fourth internal division ratio when the third internal division ratio is equal to the first internal division ratio and the fourth internal division ratio. As internal division ratio respectively equal to said second internal ratio, after re-arranging the second color point, the color point of the second first
A recording medium on which a function for associating the color point of and a computer program for causing a computer to realize. 9. The method according to claim 1, wherein the first and second color solids existing in the L ^* a ^* b ^* color space belong to the first color solid.
A computer program for recording a computer program for associating the color point of the second color point with the second color point belonging to the second color solid, wherein in the L ^* a ^* b ^* color space, A function of setting an iso-hue plane including the ^* axis and passing through the first color point; a first intersection plane area obtained by intersection of the first color solid and the iso-hue plane; A function for respectively obtaining a second intersecting plane area obtained by intersecting the color solid and the iso-hue plane; and a lightness among the color points existing on the L ^* axis in the first intersecting plane area. Setting a first reference point located between a first achromatic color point, which is a high color point, and a second achromatic color point, which is a color point having the lowest lightness, and the second intersection plane area of the color points present on the L ^* axis of the inner, first a high color point most luminosity And a function of setting a second reference point located between the achromatic color point and the fourth achromatic color point, which is the color point having the lowest lightness. A first line segment connecting the highest saturation color point and the first reference point is obtained, and a second highest saturation color point and the second reference point existing in the second intersection plane area are obtained. And a function for obtaining a second line segment connecting the first and second lines, and on the equal hue plane, the first axis is parallel to a saturation axis arranged so as to be orthogonal to the L ^* axis, and
Of the first reference straight line passing through the achromatic point and the second reference straight line passing through the second achromatic point, on the same side as the first color point with the first line segment as a boundary A first intersection point obtained by intersecting a first selection reference straight line that intersects with a first straight line that is parallel to the L ^* axis and passes through the first color point. A function for obtaining a second intersection obtained by intersecting the first line segment and the first straight line; and a third line segment having the first and second intersections as end points. A function for calculating a first internal division ratio when one color point is internally divided; and an achromatic point existing on the first selection reference straight line among the first and second achromatic points; Said first reference point;
A function for obtaining a first internally dividing point that internally divides a fourth line segment having each of the end points at the first internally dividing ratio, and on the same hue plane, being parallel to the saturation axis. And a third reference straight line passing through the third achromatic point and a fourth reference straight line passing through the fourth achromatic point. A second selection reference straight line located on the same side as the reference straight line intersects with a second straight line that is parallel to the L ^* axis and passes through the second highest chroma color point. A function for obtaining a third intersection obtained by: a color point existing on the second selection reference line among the third and fourth achromatic points; and a second reference point;
A function for obtaining a second internally dividing point that internally divides a fifth line segment having each of the end points at the first internally dividing ratio, and the second highest color saturation point and the third intersection point A function of obtaining a third internally dividing point that internally divides a sixth line segment each having an end point at the first internally dividing ratio, and the first internally dividing point as a starting point, and the first color A first half line passing through a point, a periphery of the first intersection plane region,
And a function for obtaining a fourth intersection obtained by intersection of the first color point, and the first color point internally divides a seventh line segment having the first intersection point and the fourth intersection point as end points. A function of obtaining a second internal dividing ratio at the time; a second half line starting from the second internal dividing point and passing through the third internal dividing point; and a periphery of the second intersecting plane region When,
And a function for obtaining a fifth intersection obtained by the intersection of the second intersection and an eighth line segment having the second interior division point and the fifth intersection point as end points at the second internal division ratio. A fifth subdivision point to be obtained, and using the fifth subdivision point as the second color point
A recording medium on which a function for associating the color point of and a computer program for causing a computer to realize.