JP2003244461A - Color gamut calculation method and apparatus therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a color gamut calculation method and an apparatus therefor in which a sectional area cutting a color solid on an arbitrary plane can be easily calculated at high speed. <P>SOLUTION: In the color gamut calculation method for calculating the sectional area of the prescribed color solid defined within a color space, a polygonal plane is specified within the color solid (S202), a plurality of vectors extended along the polygonal plane approximately vertically to the respective sides of that plane are set (S203), intersections of the plurality of vectors and the outer periphery of the color solid are found (S204), and these intersections are mutually connected to calculate the sectional area of the color solid (S206). <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color gamut calculation method and apparatus, and more particularly to a color gamut calculation method and apparatus for calculating a cross-sectional area in a color solid.

[0002]

2. Description of the Related Art Generally, in a computer system or the like, when a color image displayed on a color monitor is printed by a color printer, the display color on the color monitor and the color reproduction area by the printer are greatly different from each other. A technique for perceptually matching the color specifications between the displayed color image and the printed image is required. As a technique for absorbing such a difference in perceptual tint of a color image displayed / output between display media having different color gamuts, gamut mapping (mapping one color gamut into another color gamut) is performed. gamut mapping) technology exists.

Here, in this gamut mapping, in order to achieve good perceptual color matching, the difference in color reproduction range in the color monitor or color printer is calculated in advance, and based on the calculation result. Must control the mapping. As a typical method of calculating the difference in the color reproduction range, there is a method of calculating an arbitrary cross-sectional area in a color solid.

As a method of calculating the cross-sectional area, C
In AD (Computer Aided Design) or the like, there is an algorithm for calculating a line of intersection between an object and a plane by a polygon or free-form surface expression. According to these intersection line calculation algorithms, the intersection line with the polygon or the free-form surface can be calculated relatively accurately.

[0005]

In gamut mapping, a large number of cross-sectional areas need to be calculated in one mapping, so that an algorithm as fast as possible is required. However, the algorithm used in the above-mentioned CAD or the like is not so fast. On the other hand, in the calculation processing of the cross-sectional area by gamut mapping,
It is not required to be as accurate as the intersection line calculation algorithm in CAD or the like. As described above, there is a big difference between the performance of the intersection line calculation algorithm in CAD and the like and the performance of the intersection line calculation algorithm required by gamut mapping. There is a problem in calculating an arbitrary cross-sectional area in the color solid in gamut mapping by using.

The present invention has been made in view of the above conventional example, and an object of the present invention is to provide a color gamut calculation method and apparatus capable of simply and rapidly calculating a cross-sectional area obtained by cutting a color solid in an arbitrary plane. .

[0007]

In order to achieve the above object, a color gamut calculation device of the present invention has the following configuration.
That is, a color gamut calculation device for calculating a cross-sectional area of a predetermined color solid defined in a color space, comprising means for defining a polygonal plane in the color solid, and each side of the polygonal plane. A means for setting a plurality of vectors extending along the plane substantially perpendicular to, a cross point detecting means for obtaining a cross point between each of the plurality of vectors and the outer periphery of the color solid, and connecting the cross points with each other. And a cross-sectional area calculating means for calculating the cross-sectional area.

In order to achieve the above object, the color gamut calculation device of the present invention has the following configuration. That is, a color gamut calculation device for calculating a cross-sectional area of a predetermined color solid defined in a color space, wherein a plane connecting one point in the color space and a plurality of points on the outer circumference of the color solid is defined. Means for defining, means for setting a plurality of vectors extending in the outer peripheral direction from a point in the color space in the plane, and intersection point detection for obtaining an intersection of each of the plurality of vectors and the outer periphery of the color solid And a cross-sectional area calculation unit that calculates the cross-sectional area by connecting the intersections.

In order to achieve the above object, the color gamut calculation method of the present invention comprises the following steps. That is, a color gamut calculation method for calculating a cross-sectional area of a predetermined color solid defined in a color space, the step of defining a polygonal plane in the color solid, and each side of the polygonal plane. A step of setting a plurality of vectors extending along the plane substantially perpendicular to, a crossing point detection step of obtaining a crossing point of each of the plurality of vectors and the outer periphery of the color solid, and connecting the crossing points with each other. And a cross-sectional area calculating step of calculating the cross-sectional area.

In order to achieve the above object, the color gamut calculation method of the present invention comprises the following steps. That is, a color gamut calculation method for calculating a cross-sectional area of a predetermined color solid defined in a color space, wherein a plane connecting one point in the color space and a plurality of points on the outer circumference of the color solid is defined. A step of defining, a step of setting a plurality of vectors extending from the point in the color space in the plane in the outer peripheral direction in the plane, and an intersection point detection for obtaining an intersection point of each of the plurality of vectors and an outer periphery of the color solid And a cross-sectional area calculation step of calculating the cross-sectional area by connecting the intersections.

[0011]

Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

<First Embodiment> FIG. 1 is a block diagram showing the schematic arrangement of an image processing apparatus for calculating a gamut cross-sectional area according to an embodiment of the present invention.

In the figure, 101 is a CPU, 102 is a main memory, and has a RAM. 103 is a display unit such as a color monitor, 104 is an output unit such as a color printer,
Reference numeral 105 is an HDD, 106 is a ROM, 107 is an I / O circuit, and 108 is an input unit such as a keyboard and a mouse.
In addition to this configuration, it is desirable to have a network interface so that communication with a LAN, the Internet, or the like can be performed.

In the above structure, the CPU 101 is
According to the programs and data stored in the OM 102 and the HDD 105, a gamut cross-sectional area calculation process described later is executed. Also, these ROM 106 or HDD 1
In 05, Lab of the result of measuring the color chart / patch image etc.
It is assumed that the value is stored. When executing the program, the program stored in the HDD 105 is temporarily loaded into the main memory 102 and executed under the control of the CPU 101. This main memory 102 is a CPU
It is also used as a work memory for temporarily storing various data when the control processing by 101 is executed.

[First Embodiment] The calculation processing of the gamut cross-sectional area according to the first embodiment will be described below with reference to the flowchart of FIG.

FIG. 2 is a flow chart showing the gamut cross-section area calculation processing executed by the image processing apparatus according to the first embodiment. The program for executing this processing is the HDD.
It is stored in 105 and is loaded into the main memory 102 and executed by the CPU 101.

First, in step S201, from the Lab data stored in the ROM 106 or HDD 105, polyhedron (polygon) data representing the gamut surface is generated.

FIG. 3 is a diagram showing an example of this polyhedron data.

In FIG. 3, reference numeral 30 denotes a polyhedron represented in the L * a * b * space, 31 denotes a point in the L * a * b * space, and 32 denotes a hue, which will be described later. Arbitrary points P and 33 that are shown respectively indicate points representing black.

Next, in step S202, by designating one point P on the surface of this polyhedron, as shown in FIG. 4, points (white (point 31) -P (point 32) -black (point 33)) are selected. A triangle 40 connecting the three points is defined. This triangle 40 shows the equal hue plane in this L * a * b * space. Next, in step S203, the triangle 4
A vector 42 perpendicular to the side 41 connecting the point 31 (white) of 0 and the point P32 is generated at equal intervals as shown in FIG. It is assumed that these vectors 42 are located on the same infinite plane as the triangle 40 in the L * a * b * space. Next, in step S204, these vectors 42
And the intersection with the outer periphery of the polyhedron 30 shown in FIG. Next, the process proceeds to step S205, and it is confirmed whether or not the calculation process of the intersection with the outer periphery of the polyhedron 30 is completed for all of these vectors 42, and if not completed, the process returns to step S204. When all the intersections are calculated in step S205, the process proceeds to step S206, and all the intersections 43 (FIG. 6) obtained in step S204 are connected to the points 31 and P by a straight line.

This is shown in FIG. In FIG.
A straight line 44 connecting these points is shown by a chain line,
As a result, it is possible to acquire the cross-section line from the point 31 indicating white to the point P (32).

Next, from this point P (32) to a point 3 indicating black.
Similarly, the cross-section line 45 up to 3 can be acquired by performing the same processing as the side 41 on the side connecting the point 33 and the point P. As a result, point 31 (white) -point P (3
2) -The calculation processing of the cross-sectional area of the equal hue defined by the point 33 (black) is completed.

In the first embodiment, the vertical vectors 42 are generated at equal intervals from the sides of the triangle 40 showing the equal hue plane, but the intervals of these vectors 42 may be unequal. Absent. Further, the line connecting the vector 42 and the intersection of the outer periphery of the polyhedron is not limited to a straight line, and a curve such as a spline may be used. Further, as a means for expressing the gamut surface, a triangular patch or a free-form surface may be used in addition to the polyhedron.

In this way, in L * a * b * space, a triangle of equal hue is defined, and the intersection point of the vector perpendicular to the boundary (side) of the triangle and the outer periphery of the polyhedron expressing the gamut surface is By connecting points on the axis L * indicating white and black, it is possible to obtain a gamut cross section line of an arbitrary hue.

[Second Embodiment] In the first embodiment described above, the process of calculating the gamut cross-sectional area of equal hue has been described. In the second embodiment, the equal lightness (L *) is obtained.
Calculate the gamut cross-section area at.

The method of calculating the gamut cross-sectional area of equal brightness according to the second embodiment will be described below with reference to the flowchart of FIG.

FIG. 7 shows L according to the second embodiment of the present invention.
It is a flowchart which shows the calculation process of the gamut cross-section area | region where brightness is equal in the * a * b * area. The hardware configuration of the image processing apparatus according to the second embodiment is the same as that of the first embodiment described above, and the program for executing this processing is stored in the HDD 105, and the main memory 1
02 and is executed by the CPU 101.

First, in step S701, a polyhedron representing a gamut surface is generated from L * a * b * data as in the first embodiment.

FIG. 8 shows a polyhedron 8 representing a gamut surface.
It is the figure which looked at 0 from the upper part (white) side of the L ingredient.

Next, in step S702, the lightness at which the polyhedron 80 is cut is designated by the L * value. Next, proceeding to step S703, in the L * a * b * space, the hexagonal surface 90 having the specified lightness (L * value) is set as shown in FIG. This plane 90 is perpendicular to the L * axis and is a *, b *.
Parallel to the axis.

FIG. 9 shows a hexagonal equi-brightness surface 90 cut at the lightness (L * value) in the three-dimensional space indicated by L *, a *, and b *.

Next, in step S704, a vector located on the same infinite plane as the hexagonal equi-brightness surface 90 and perpendicular to each side of the hexagon is generated as shown in FIG. Next, in step S705, the intersections of these vectors and the outer periphery of the polyhedron 80 are calculated, as in the first embodiment described above.

Next, in step S706, it is confirmed whether or not the calculation for obtaining the intersection with the outer periphery of the polyhedron 80 has been completed for all these vectors, and if not completed, step S705 is repeated. If the calculation for obtaining the intersection is completed, the process proceeds to step S07, the calculated intersections are connected by a straight line, and the calculation process of the gamut cross-sectional area at the specified brightness is completed.

In FIG. 10, a plurality of vectors perpendicular to each side of the hexagonal equi-brightness surface 90 are defined.
By connecting the intersections of these vectors and the outer periphery of the polyhedron 80, the gamut cross-sectional area at the specified lightness (L * value) is defined. It should be noted that the intervals of the vectors perpendicular to each side in FIG. 10 do not have to be constant.

With the above method, it is possible to calculate the gamut cross-sectional area at equal brightness.

[Embodiment 3] Embodiments 1 and 2 above
In the above, the method of calculating the gamut cross-sectional area with the constraint conditions of equal hue and equal lightness is described, but in the third embodiment, an arbitrary cross-sectional area is calculated.

The calculation processing of an arbitrary gamut cross sectional area according to the third embodiment will be described below with reference to the flowchart of FIG.

FIG. 11 shows a third embodiment of the present invention.
It is a flowchart which shows the calculation process of the gamut cross-section area | region in L * a * b * area. The hardware configuration of the image processing apparatus according to the third embodiment is the same as that of the first embodiment, and the program for executing this processing is HD.
It is stored in D105, is loaded into the main memory 102, and is executed by the CPU 101.

First, in step S1101, a polyhedron representing a gamut surface is generated from Lab data as in the first and second embodiments. Next, step S110.
Go to 2 and specify 3 points on this polyhedron. here,
The plane including these three points becomes the cut surface of the gamut.

FIG. 12 is a diagram showing an example of points 121, 122, 123 located on the polyhedron 120. Figure 1
2 is a view of the polyhedron 120 expressing the gamut surface as seen from the upper (white) side of the L component.

Next, in step S1103, these 3
A triangle 130 formed by connecting points (121, 122, 123) is defined as shown in FIG.

Next, in step S1104, a vector which is located on the same infinite plane as this triangle 130 and which is vertical from each side of this triangle 130 is generated as shown in FIG. And each of these vectors and polyhedron 1
An intersection with the outer circumference of 20 is obtained, and the intersections are connected to each other to calculate the gamut cross-sectional area shown in FIG. This processing is executed in steps S1105 to S1107 in FIG. 11, and since these processings are the same as the processings in the above-described first and second embodiments, description thereof will be omitted.

Although the interval between the plurality of vertical vectors shown in FIG. 14 has been described as constant, it may not be constant.

In the first to third embodiments described above, polygons such as triangles or hexagons are arranged in the L * a * b * space, and a vector and a color solid perpendicular to each side of the polygon are arranged. Although the gamut cross-sectional area is defined by obtaining the intersection with the outer circumference of, the gamut cross-sectional area can be defined by the same means by arranging geometric figures other than polygons, for example, ellipses. FIG. 18 shows an ellipse 150 defined in the L * a * b * space. A plurality of tangent lines are defined on the circumference of an elliptical shape as shown in the figure, and as shown in FIG. 19, the gamut cross-sectional area is calculated by finding the intersection of the vector perpendicular to each tangent line and the outer circumference of the color solid.

By the above method, it is possible to calculate the cut surface of the gamut with an arbitrary plane.

[Fourth Embodiment] In the first to third embodiments, a polygon such as a triangle or a hexagon is arranged in the L * a * b * space, and a vector perpendicular to each side of the polygon. The cross section area of the gamut was defined by finding the intersection point of the and the outer circumference of the color solid. On the other hand, in the fourth embodiment, a vector is generated without using the above-described polygon and the gamut cross-sectional area is calculated.

The method for calculating the gamut cross-sectional area in this embodiment will be described below.

FIG. 15 shows the fourth embodiment of the present invention.
It is a flowchart which shows the calculation process of the gamut cross-section area | region in L * a * b * area. The hardware configuration of the image processing apparatus according to the fourth embodiment is the same as that of the first embodiment, and the program for executing this processing is HD.
It is stored in D105, is loaded into the main memory 102, and is executed by the CPU 101.

First, in step S1501, polyhedron data is generated based on Lab data, as in each of the above embodiments. Next, proceeding to step S1502, arbitrary two points are designated on this polyhedron.

FIG. 16 shows an example of the polyhedron 160 and designated two points 151 and 152.

Next, in step S1503, the designated points 151 and 152 and the origin 17 of the L * a * b * space are set.
Define a plane defined by 0 (FIG. 17) (point whose Lab value is (0,0,0)). Next, proceeding to step S1504, a vector located on this plane is generated as shown in FIG.

In FIG. 17, from the origin 170 to the point 16
Straight lines 171 and 172 connecting 1, 162 are defined respectively, and a plurality of vectors passing through the origin 170 are generated on the plane formed by the origin 170 and the points 161 and 162.

Next, in step S1505, the intersections of these vectors and the outer periphery of the polyhedron 160 are calculated. Then, the gamut cross-sectional area is calculated by connecting these intersections and the origin. This processing is executed in steps S1506 to S1507 in FIG. 15, and since the processing is the same as the processing in the first to third embodiments described above, the description thereof will be omitted.

In the fourth embodiment, the color three-dimensional cross sectional area is calculated by the plane defined by the designated two points on the polyhedron and the origin. However, the present invention is not limited to this and, for example, on the polyhedron. It is also possible to calculate the color three-dimensional cross-sectional area by the plane defined by any three points.

In the fourth embodiment, the vectors from the origin are generated at equal angular intervals, but they may be set at unequal angular intervals.

(Other Embodiments) As described above, the object of the present invention is to provide a storage medium having a program code of software for implementing the functions of the embodiments to a system or apparatus, and to provide a computer of the system or apparatus. It is also achieved by (or CPU or MPU) reading and executing the program code stored in the storage medium. In this case, the program code itself read from the storage medium realizes the functions of the above-described embodiments, and the storage medium storing the program code constitutes the present invention. As a storage medium for supplying such a program code, for example, a floppy disk, hard disk, optical disk, magneto-optical disk, CD-ROM, CD-R, magnetic tape, non-volatile memory card, ROM, etc. may be used. You can

Further, by executing the program code read by the computer, not only the functions of the above-described embodiment are realized, but also the OS (operating system) running on the computer is operated based on the instruction of the program code. This also includes the case where the system) performs a part or all of the actual processing and the processing realizes the functions of the above-described embodiments.

Further, after the program code read from the storage medium is written in the memory provided in the function expansion board inserted into the computer or the function expansion unit connected to the computer, based on the instruction of the program code. , The CPU included in the function expansion board or function expansion unit performs a part or all of the actual processing,
It also includes the case where the functions of the above-described embodiments are realized by the processing.

As described above, radial vectors are generated from a point in the L * a * b * space along a desired plane, intersections between these vectors and the outer circumference of the color solid are obtained, and these intersections are connected. Thus, the cross-sectional area of the color solid can be easily calculated.

As described above, according to the present embodiment, the intersection point between the plurality of vectors having the constraint condition on the L * a * b * space and the outer circumference of the color solid representing the gamut surface is calculated. However, by connecting these intersections, it becomes possible to calculate an arbitrary gamut cross-sectional area quickly and easily.

In the above embodiment, the Lab space has been described as an example of the color space that defines the colors, but the present invention is not limited to this. For example, the RGB color system, the CMY color system, the XYZ color system. It may be a color system such as a color system or a Luv color system.

[0062]

As described above, according to the present invention, there is an effect that a cross-sectional area obtained by cutting a color solid on an arbitrary plane can be calculated easily and at high speed.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an image processing apparatus according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a gamut cross-sectional area calculation process according to the first embodiment of the present invention.

FIG. 3 is a diagram showing an example of polyhedral data expressing a gamut defined in an L * a * b * space according to the first embodiment.

FIG. 4 is a diagram showing an example of triangular surfaces of equal hue for cutting a polyhedron expressing a gamut defined in the L * a * b * space according to the first embodiment.

FIG. 5 is a diagram showing vectors perpendicular to sides on a triangular surface according to the first embodiment.

FIG. 6 is a diagram illustrating a section line from a point indicating white to a point P on a designated polyhedron according to the first embodiment.

FIG. 7 is a flowchart illustrating a gamut cross-sectional area calculation process according to the second embodiment of the present invention.

FIG. 8 is a diagram showing an example of polyhedral data expressing a gamut defined in an L * a * b * space according to the second embodiment.

FIG. 9 is a diagram showing an example of a hexagon that cuts a gamut at a specified L * value in the second embodiment.

FIG. 10 is a diagram illustrating a vector located on the same infinite plane as a hexagon and perpendicular to each side in the second embodiment.

FIG. 11 is a flowchart illustrating a gamut cross-sectional area calculation process according to the third embodiment of the present invention.

FIG. 12 is a diagram showing three points designated as a polyhedron expressing a gamut defined in an L * a * b * space according to the second embodiment.

13 is a diagram showing a triangle connecting the three points in FIG.

FIG. 14 is a diagram showing a vector which is located on the same infinite plane as the triangle of FIG. 13 and which is perpendicular to each side.

FIG. 15 is a flowchart illustrating a gamut cross-sectional area calculation process according to the fourth embodiment of the present invention.

FIG. 16 is a diagram showing an example of two points designated as a polyhedron expressing a gamut surface according to the fourth embodiment.

FIG. 17 is a diagram showing an example of vectors generated radially from the origin of the L * a * b * space along the cutting plane according to the fourth embodiment.

FIG. 18 is a diagram showing an example of an ellipse for cutting a gamut.

19 is a diagram showing a vector which is located on the same infinite plane as the ellipse of FIG. 18 and which is perpendicular to the tangent to the circumference.

Continued front page    F-term (reference) 5B050 BA07 BA09 EA09 EA27 EA28                       FA02 FA09                 5B057 CB01 CB08 CB13 CB17 CC04                       CE17 CE18                 5C077 LL18 MP08 PP36 PP37 PQ12                       TT02                 5C079 HB08 HB11 LA02 LB02 MA11                       MA17 NA03 NA11 PA03

Claims (28)

[Claims] 1. A color gamut calculation method for calculating a cross-sectional area of a predetermined color solid defined in a color space, the method comprising: defining a polygonal plane in the color solid; A step of setting a plurality of vectors extending along the plane substantially perpendicularly to each side of, an intersection point detecting step of obtaining an intersection point of each of the plurality of vectors and the outer periphery of the color solid, and the intersection points And a cross-sectional area calculating step of calculating the cross-sectional area by tying together the color gamut calculation method. 2. A color gamut calculation method for calculating a cross-sectional area of a predetermined color solid defined in a color space, comprising: defining an elliptical plane in the color solid; A step of setting a plurality of vectors extending along the plane substantially perpendicular to the tangent line, an intersection point detecting step of obtaining an intersection point of each of the plurality of vectors and the outer periphery of the color solid, and the intersection points And a cross-sectional area calculating step of connecting the cross-sectional areas to calculate the cross-sectional area. 3. The color solid is represented by a polygon, a triangular patch, or a free-form surface.
Or the color gamut calculation method described in 2. 4. The color gamut calculation method according to claim 1, wherein the planes are planes having the same hue. 5. The color gamut calculation method according to claim 1, wherein the plane is a plane having the same lightness. 6. The plane is a plane formed by points indicating white and black on the lightness axis and points on the outer periphery of the color solid, and in the cross-sectional area calculation step, the white and black are defined. The color gamut calculation method according to any one of claims 1 to 4, wherein a point shown and the intersection are connected. 7. The color gamut calculation method according to claim 1, wherein the plane is a plane formed by a hexagon passing through a point having a predetermined lightness on the lightness axis. 8. The color gamut calculation method according to claim 1, wherein the plane is a plane defined by a triangle formed by connecting arbitrary three points on the outer periphery of the color solid. 9. A color gamut calculation method for calculating a cross-sectional area of a predetermined color solid defined in a color space, wherein one point in the color space and a plurality of points on the outer circumference of the color solid are calculated. A step of defining a connecting plane, a step of setting a plurality of vectors extending in the outer peripheral direction from a point in the color space in the plane, and an intersection of each of the plurality of vectors and the outer periphery of the color solid. A color gamut calculation method comprising: a crossing point detection step for obtaining; and a cross-sectional area calculation step for connecting the crossing points to calculate the cross-sectional area. 10. The color gamut calculation method according to claim 9, wherein the color solid is represented by a polygon, a triangular patch, or a free-form surface. 11. The color space is an RGB color system, CMY.
11. The color gamut calculation method according to claim 1, which is represented by any one of a color system, an XYZ color system, a Luv color system, and a Lab color system. 12. The color gamut calculation method according to claim 1, wherein in the step of setting the plurality of vectors, the plurality of vectors are arranged and set at substantially equal intervals. 13. The step of setting the plurality of vectors, wherein the plurality of vectors are set radially from points in the color space along the plane. The color gamut calculation method according to item 1. 14. A program for executing the color gamut calculation method according to claim 1. Description: 15. A computer-readable storage medium having the program according to claim 14 stored therein. 16. A color gamut calculation device for calculating a cross-sectional area of a predetermined color solid defined in a color space, comprising means for defining a polygonal plane in the color solid, and the polygonal plane. Means for setting a plurality of vectors extending along the plane substantially perpendicularly to each side of, a crossing point detection means for obtaining a crossing point between each of the plurality of vectors and the outer periphery of the color solid, and the crossing points And a cross-sectional area calculating unit that calculates the cross-sectional area by connecting to each other. 17. A color gamut calculation device for calculating a cross-sectional area of a predetermined color solid defined in a color space, comprising means for defining an elliptical plane in the color solid, and a plurality of the elliptical plurality. Means for setting a plurality of vectors extending along the plane substantially perpendicular to the tangent line, intersection point detecting means for obtaining an intersection point between each of the plurality of vectors and the outer periphery of the color solid, and the intersection points A cross-sectional area calculation unit that connects the cross-sectional areas to each other to calculate the cross-sectional area. 18. The color gamut calculation device according to claim 16, wherein the color solid is represented by a polygon, a triangular patch, or a free-form surface. 19. The plane according to claim 16, wherein the planes have the same hue.
The color gamut calculation device according to item. 20. The plane according to claim 16, wherein the plane is a plane having the same brightness.
The color gamut calculation device according to item. 21. The plane is a plane formed by points indicating white and black on the lightness axis and points on the outer periphery of the color solid, and the cross-sectional area calculation means defines the white and black. The color gamut calculation device according to any one of claims 16 to 19, wherein a point shown and the intersection are connected. 22. The color gamut calculation device according to claim 16, wherein the plane is a hexagonal plane that passes through a point having a predetermined lightness on the lightness axis. 23. The color gamut calculation device according to claim 16, wherein the plane is a plane defined by a triangle formed by connecting arbitrary three points on the outer periphery of the color solid. 24. A color gamut calculation device for calculating a cross-sectional area of a predetermined color solid defined in a color space, wherein one point in the color space and a plurality of points on the outer circumference of the color solid are defined. Means for defining a connecting plane, means for setting a plurality of vectors extending in the outer peripheral direction from a point in the color space in the plane, an intersection of each of the plurality of vectors and the outer periphery of the color solid A color gamut calculation device comprising: an intersecting point detecting unit for obtaining; and a cross sectional region calculating unit for connecting the intersecting points to calculate the cross sectional region. 25. The color gamut calculation device according to claim 24, wherein the color solid is represented by a polygon, a triangular patch, or a free-form surface. 26. The color space is an RGB color system, CMY.
The color gamut calculation device according to any one of claims 16 to 25, which is represented by any one of a color system, an XYZ color system, a Luv color system, and a Lab color system. 27. The color gamut calculation device according to claim 16, wherein the means for setting the plurality of vectors arranges and sets the plurality of vectors at substantially equal intervals. 28. The means for setting the plurality of vectors sets the plurality of vectors radially from a point in the color space along the plane. The color gamut calculation device according to item 1.