JP2003179764A - Color correction table fomring method and apparatus, control program and storage medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve color reproducibility by controlling a smoothing condition for each of plural positions on color space. <P>SOLUTION: When a color correction table is formed by performing smoothing, smoothing conditions respectively corresponding to the multiple positions on the color space are set, and then the smoothing is performed according to the smoothing conditions. <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 correction table creating method and apparatus, a control program, and a storage medium.

[0002]

2. Description of the Related Art Generally, when an image displayed on a monitor is printed out from a printer in a computer system or the like, the color gamuts of the monitor and the printer are largely different from each other. A so-called color matching process is required to adjust so that the values become substantially equal. As the color matching processing, for example, a color correction method is known in which an interpolation calculation is performed by referring to a color correction lookup table (hereinafter, color correction table) in consideration of color characteristics of a monitor and a printer.

However, in the process of creating the color correction table, various noises may be generated and mixed into the values of the created color correction table. For example, color measurement is generally performed in order to know the actual characteristics of the printer, but the measurement error during color measurement may cause the noise. Other causes of noise include a quantization error when quantizing the calculation processing result. If the noise generated due to the above reason is mixed in the color correction table, the change in the value of the table becomes not smooth. As a result, the gradation change is not smooth in the color-corrected image, and when the image is printed by a printer, problems such as false contours are likely to occur.

Therefore, in order to remove the noise of the color correction table, conventionally, the value of the color correction table has been smoothed by using a shift invariant filter.

[0005]

However, when the same smoothing processing is performed on all the values of the color correction table as in the above-mentioned conventional technique, the values of the areas where smoothing is not required so much are smoothed. The value will change from the value before conversion processing. As an example of the area in which the smoothing is not required so much, it is judged in the color correction table that the value is already changed smoothly before the smoothing processing, or the smoothing is performed from a colorimetric or subjective viewpoint. For example, a region where it is desired to suppress the fluctuation of the value due to the processing is included. Further, even when it is judged from the image printed by the printer that it is desirable to intensively execute the smoothing process only on a specific area in the color space, it is difficult to realize it by the above-mentioned conventional technique. As a result, the smoothness due to the smoothing cannot be changed for each color region, and it has been impossible to create a color correction table for obtaining an image of which image quality is more preferable for the user.

The present invention has been made to solve the above problems, and it is possible to improve color reproducibility by making it possible to control a smoothing condition for each of a plurality of positions in a color space. To aim.

[0007]

As one means for achieving the above object, the color correction table creating method of the present invention has the following configuration.

In a color correction table creating method for creating a color correction table by performing smoothing, smoothing conditions corresponding to a plurality of positions in a color space are set, and smoothing is performed according to the smoothing conditions. Is characterized by.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below with reference to the drawings.

<First Embodiment> FIG. 1 is a block diagram showing the arrangement of an image processing apparatus to which the color adjusting apparatus according to this embodiment is applied. A color monitor 20 for displaying an image and an image on a recording medium are shown. The printer 27 for printing is shown connected to the image processing apparatus 28. As components of the image processing device 28, 21 is a video signal generation unit for converting image data into a video signal, 22 is a memory for storing image data, and 23 is a color in which correspondence between monitor display and print color is stored. Correction table, 24 is color correction table 2
3, a color matching processing unit for matching monitor display and print colors, 25 a smoothing unit for smoothing the data stored in the color correction table 23, and 26 converting image data into printer drive signals. Is an output image processing unit for

In this embodiment, the image data to be processed is data digitized by an image input device such as a digital camera or a scanner, or data generated as computer graphics (CG). It is assumed that the corresponding pixel value is previously stored in the image memory 22. Specifically, each pixel value has an 8-bit value of red (R), green (G), and blue (B).

In this embodiment, the color monitor 20 is a display device such as a CRT or LCD. The printer 27 is of an inkjet type, and ejects and fixes cyan (C), magenta (M), yellow (Y), and black (K) ink droplets on the output paper, and expresses the density of the color by its density. I shall. The color monitor 20 and the printer 27 are not limited to such a form, and the printer 27 may be of another type such as an electrophotographic type or a thermal transfer type.

In the present embodiment, the color correction table 2
Reference numeral 3 is a table for performing color correction processing for considering the output characteristics of the printer 27 with respect to input RGB values.
The correspondence between the color coordinate data of grid points regularly arranged in the B color space and the color coordinate data after the color correction processing is stored. FIG. 2 is a schematic diagram showing grid points before color correction processing in the RGB color space. In FIG. 2, R
The number of grid points is 7 for each of the axes G, B, and black (Bk), green (G), red (R), cyan (C), magenta (M), and white (W). R, G, and RGB coordinates of the sample points according to the grid numbers. FIG. 3 is a diagram showing details of the color correction table 23. As shown in the figure, the R / G / B value step is shown at the head of the table, and subsequently the color correction data is stored. FIG. 4 shows a schematic diagram of the grid points after the color correction processing by the color correction data 23. In FIG. 4, RGB (R) values after color correction of sample points corresponding to black (Bk), green (G), red (R), cyan (C), magenta (M), and white (W), and samples by grid numbers The grid coordinates of the points are marked.

In the image processing apparatus shown in FIG. 1, the image data stored in the image memory 22 is supplied to the color matching processing section 24. Color matching processing unit 24
In (1), color matching is performed on the image displayed on the color monitor 20 via the video signal generation unit 21 and the output image printed by the printer 27 via the output image processing unit 26. Specifically, the output value corresponding to each pixel value of the image data is obtained by interpolating with reference to the color correction table 23. After that, the output image processing unit 26 controls the ejection of each ink of CMYK with respect to the input RGB pixel values, so that the printer 27 reproduces a desired color on the recording medium.

In the present embodiment, when the user determines that the gradation is not good for one or more hues from the output image printed as described above, the smoothing section 25 performs color correction. It is characterized in that the table 23 is subjected to smoothing processing to enable color matching processing desired by the user.

The processing in the smoothing section 25 will be described below.

FIG. 5 is a block diagram showing a detailed structure of the smoothing unit 25. In the figure, reference numeral 10 denotes a parameter designating unit in which a user sets a smoothing condition when the RGB values stored in the color correction table 23 are moved by the smoothing process, for example, a limit value of a color change amount in each hue. It Reference numeral 11 denotes a change amount limit value calculation unit, which calculates a change amount limit value at each grid point on the color space corresponding to all grids of the color correction table 23 from the change amount limit value for each hue designated by the parameter designation unit 10. To calculate. A change amount limit value table 12 stores the values calculated by the change amount limit value calculation unit 11. A temporary smoothing unit 13 smoothes the RGB values stored in the color correction table 23 by filtering or the like. A change amount calculation unit 14 calculates a color difference ΔE between the RGB value smoothed by the temporary smoothing unit 13 and the RGB value before smoothing. A correction unit 15 corrects the RGB value calculated in the temporary smoothing 13 based on ΔE calculated in the change amount calculation unit 14 and stores the RGB value in the color correction table 23.

FIG. 6 is an example of a user interface (UI) in the parameter designation section 10. The user uses this UI to specify the change amount limit value of the RGB value before and after smoothing using the color difference ΔE. The variation limit value is a plurality of representative colors, that is, red (R), green (G), blue (B), cyan (C), magenta (M), and yellow (Y) hues as shown in FIG. Shall be specified.

FIG. 7 is a diagram showing details of the change amount limit value table 12. As shown in the figure, the change amount limit value table 12 stores the change amount limit value corresponding to each grid point of the color correction table 23.

The smoothing process in the color adjusting device 28 of this embodiment will be described in detail below with reference to the flowchart of FIG.

First, in step S100, the parameter designating unit 10 designates the above-described variation limit value for each hue. Next, in step S101, the change amount limit value calculation unit 11 calculates the change amount limit value corresponding to each grid point of the color correction table 23 by the method described later based on the value specified in step S100, and the change amount is calculated. Limit value table 12
To store. Then, in step S102, the temporary smoothing unit 13
In, the smoothing process (hereinafter referred to as temporary smoothing) in the RGB color space is performed on each value stored in the color correction table 23. The temporary smoothing process may be performed by averaging RGB values of grid points adjacent to each other in the directions of the RGB axes,
It may be performed by using a filter such as Gaussian.

In step S103, the change amount calculation unit 14
Is R after the provisional smoothing processing obtained in step S102.
A color difference ΔE between the GB value and the RGB value before the temporary smoothing process is calculated. ΔE corresponding to the RGB values before and after smoothing is calculated as follows. First, on a computer system, patch coordinate images before and after smoothing are created using color coordinate data of grid points regularly arranged in the RGB color space as color patches, and the patch images are output by the printer 27 and output. To obtain the L * a * b * value corresponding to each patch. Based on this color measurement result, L * a * b * values corresponding to the RGB values of the color correction table 23 before and after smoothing are obtained by interpolation, and the color difference is calculated from these two L * a * b * values. Calculate ΔE. ΔE corresponding to the RGB values before and after smoothing is or CIECAM97s
It is obtained by using the RGB-Lab conversion calculation in consideration of the perceptual adaptation defined in.

In step S104, the correction section 15 compares the color difference ΔE calculated in step S103 with the corresponding change amount limit value in the change amount limit value table 12, and the Δ
If E is larger than the limit value, the process proceeds to step S105, and if not, the process proceeds to step S106. Step S1
In 05, the correction unit 15 corrects the RGB values after provisional smoothing so that the color difference ΔE becomes equal to or less than the change amount limit value. FIG. 9 shows a color before smoothing (RGB
Value) P ₀ , color Ptemp after temporary smoothing, color P ′ after correction
Shows the relationship. As shown in FIG. 9, the correction unit 15 determines that the color P ′ after correction is the color P ₀ before smoothing and the color Ptem after temporary smoothing.
The above-mentioned correction processing is performed so that it is located on the line with p as the end point. Subsequently, the correction unit 15 stores the corrected RGB value in the color correction table 23 in step S106. In step S107, it is confirmed whether the smoothing process has been completed for all the values in the correction table 23, and if not completed, the processes of steps S102 to S107 are repeated. If finished, the smoothing process of the color correction table 23 is finished.

Next, a procedure for creating a change amount limit value table in the change amount limit value calculation section 11 will be described with reference to the drawings. First, in the RGB space, white (W) -representative color (RGBCMY) -black (B) shown in FIG.
The corresponding change amount limit value ΔE is stored in the change amount limit value table 12 for the lattice points located on the six hue planes of k). As the variation limit value corresponding to the grid point on the hue plane, the value designated by the parameter designating unit 10 is used. That is, in each of the hue planes of W-RGBCMY-Bk, the same variation limit value is set for all grid points on the same hue plane. However, W, R, G, B, C, M, Y,
The change amount limit value corresponding to each vertex of Bk is 0.

In this embodiment, the change amount limit value can be set for RGBCMY which is the primary color of the RGB color space indicated by RGB which is the input value of the color correction table.

Next, based on this change amount limit value, WR
The change amount limit value ΔE is obtained for the lattice point in the middle area of the GBCMY-Bk hue plane. As an example of the region, FIG. 11 shows a tetrahedral region sandwiched between the WR-Bk hue plane and the YY-Bk hue plane. For any grid point P in the tetrahedral area, the change amount limit value is calculated by the following procedure. When the grid coordinate of the arbitrary grid point P is (rp, gp, bp), first, on the line parallel to the RY line passing through the grid point P, W of the grid point P
The distance Dr from the -R-Bk hue plane and the distance Dy from the WY-Bk hue plane are calculated by the following formulas. Dr = gp-bp Dy = rp-gp

Next, the change amount limit value Ep at the grid point P is calculated by linearly interpolating the change amount limit value Er of the WR-Bk hue plane and the W-Y-Bk hue face Ey as follows. To do. Ep = Er + (Ey-Er) * Dr / (Dy + Dr)

Similarly, the lattice points in the other regions are also obtained by linearly interpolating the two change amount limit values on the adjacent hue planes. The variation limit value table 12 is created by the above method. Since it is not preferable in terms of color reproduction that the achromatic color is corrected to the chromatic color by the smoothing, the variation limit value is set to 0 for the grid points on the W-Bk line (gray).

As described above, according to this embodiment,
The user can specify the limit value for the fluctuation of the value due to the smoothing. Therefore, it is possible to control the smoothing amount according to the position in the color space, a region where smoothing is not required so much, a region where it is desired to suppress the fluctuation of the value due to the smoothing process from a colorimetric or subjective viewpoint. With respect to, the smoothing amount can be limited, and the color reproducibility can be improved as compared with the conventional case.

Further, since the smoothing amount between two adjacent hues is obtained by interpolation, problems such as pseudo contours due to smoothing hardly occur even when the two hue smoothing amounts are greatly different, and an appropriate smoothing condition is set. It is possible to set.

Further, since the smoothing amount is specified by using the distance (ΔE) in the CIE-Lab space, it becomes possible to set the smoothing amount according to the output device, the paper, etc. as a value closer to perception.

<Second Embodiment> The second embodiment of the present invention will be described below.
Will be described.

In the above-described first embodiment, an example in which the smoothing amount is designated for each of the six hues has been shown, but in the second embodiment, the six hues are further divided into two parts, a light part and a dark part,
White (W) -representative color (RGBCMY), representative color (R
It is characterized in that change amount limit values in smoothing can be designated at 12 positions of (GBCMY) -black (Bk). FIG. 12 is an example of a user interface (UI) in the parameter designation unit 10 of the second embodiment.
The user uses this UI to set the change amount limit value W-
R, WG, WB, WC, WM, WY, RB
k, G-Bk, B-Bk, C-Bk, M-Bk, Y-B
Specify for each region of k.

The method of creating the change amount limit value table 12 in the second embodiment will be described in detail below with reference to the flowchart of FIG. The configuration of the image processing apparatus in the second embodiment is the same as that in the first embodiment described above.

First, in step S200, corresponding change amount limit values are stored in the change amount limit value table 12 for the lattice points located on the 12 lines W-RGBCMY and RGBCMY-Bk in the RGB space. 1
The change amount limit value corresponding to the lattice point on the two-hue surface is specified by the parameter specifying unit 10 as described above.

Next, in step S201, the representative color 6
Lines connecting colors (R-Y, Y-G, G-C, C-B,
For the lattice points on B-M and M-R), the corresponding change amount limit value is set. FIG. 14 shows a line connecting the six representative colors. Hereinafter, a method of calculating the variation limit value Ep corresponding to the grid point P on the RY line will be described. The change amount limit values corresponding to the grid points on the other lines are also obtained by the same means.

First, the distances (number of grid points) Dr and Dy of the grid point P from R and Y are obtained. Then do the following calculations,
A change amount limit value Ep of the grid point P is calculated. Ep = Ermin + (Eymin−Ermin) * Dr
/ (Dr + Dy) Ermin = min (Ewr, Erk) Eymin = min (Ewy, Eyk) Here, Ewr, Erk, Ewy, and Eyk are WR and RB designated by the parameter designating unit 10, respectively.
The change amount limit values corresponding to k, W-Y, and Y-Bk are shown.
Min (α, β) is a function that selects a smaller value from α and β.

Further processing proceeds to step S202, where R
For the grid points located on the surface of the GB color space (cube region) (the change amount limit value is not set in steps S200 and S201), the corresponding change amount limit value is set. In step S202, the setting is performed for two representative colors adjacent to W as shown in FIG. 15, or for 12 regions formed by two adjacent representative colors and Bk. Hereinafter, a method of calculating the variation limit value Ep corresponding to the lattice point Ps on the RM-Bk plane (inside the triangle) will be described with reference to FIG. 16. First, in the B-axis direction, the distance (number of grid points) Dmk of the point Ps from the M-Bk line and the distance Drk from the R-Bk line are obtained. In FIG. 16, Ps and Dm
The relationship between k and Drk is shown. Then, the following calculation is performed to calculate the change amount limit value Eps corresponding to the grid point Ps. Eps = Emk + (Erk-Emk) * Dmk / (Dr
k + Dmk) Here, Emk represents a change amount limit value corresponding to M-Bk designated by the parameter designating unit 10. Similarly, for other points on the surface, two adjacent representative colors and W /
It is obtained by linearly interpolating the change amount limit values corresponding to the two lines having Bk as an end point.

After the change amount limit values are set for the grid points on the surface of the RGB color space in this way, the change amount limit value of the representative color (RGBCMY) -intermediate gray (Gm) line shown in FIG. 17 is set in step S203. To do. The intermediate gray (Gm) represents an intermediate grid point on the gray line. That is, when the number of grid points in each axial direction is N, the grid coordinates of Gm are (N / 2, N / 2, N / 2). As the change amount limit value corresponding to the RGBCMY-Gm lines, the change amount limit value of the W-RGBCMY line and the change amount limit value of the RGBCMY-Bk line in the same hue are compared, and the smaller value is used. For example, R-G
The change amount limit value corresponding to the grid point on the m line is set to the minimum value of the WR line limit value and the R-Bk line limit value designated by the parameter designation unit 10. .

Next, in step S204, W shown in FIG.
-RGBCMY-Gm surface and Gm-RGBCMY-B
Change amount limit values are set for grid points on the k plane (inside the triangle). Hereinafter, the lattice point P on the Gm-R-Bk plane
A method of calculating the variation limit value Ei corresponding to i will be described.
First, as shown in FIG. 19, the angles ωgm and ωk of the grid point Pi from the R-Gm line and the R-Bk line are calculated. Then, the following calculation is performed to obtain the change amount limit value Ei corresponding to the grid point Pi. Ei = Ergm + (Erk−Ergm) * ωgm / (ω
gm + ωk)

Ergm represents a variation limit value corresponding to the R-Gm line set in step S203. Similarly, for other grid points on the Gm-RGBCMY-Bk plane, Gm-RGBCMY lines and RGBCM
The change amount limit value is calculated based on the angle ratio from the Y-Bk line. For the grid points on the W-RGBCMY-Gm plane, the W-RGBCMY line and RGBCMY-G
Based on the angle ratio from the m line, the change amount limit value is calculated by the same method.

Finally, in step S205, the correspondence is made between W-adjacent two-color representative colors-Gm, and Gm-two adjacent-color representative colors-Bk with respect to the grid points inside the 12 tetrahedral regions. Set the change amount limit value. Figure 2
0 is a diagram showing the 12 tetrahedral regions. Less than,
A method of calculating the variation limit value Ecb corresponding to an arbitrary grid point Pcb in the tetrahedron region having Gm, C, B, and Bk as vertices will be described with reference to FIG. First, the grid point P
a line L parallel to the G axis, passing through cb, and Gm-B-Bk
Intersection points P1 and P2 with the hue plane and the Gm-C-Bk hue plane are obtained. The grid coordinates of the grid point Pcb are (rc, g
c, bc), the grid coordinates of the intersection points P1 and P2 are (rc, rc, bc) and (rc, bc, b), respectively.
c).

Then, the intersections P1 and P2 of the grid points Pcb
Distances D1 and D2 from are calculated by the following equations. D1 = gc-rc D2 = bc-gc

Then, by linearly interpolating the change amount limit values E1 and E2 at the intersection points P1 and P2 as follows,
The change amount limit value Ecb at the point Pcb is calculated. Ecb = E1 + (E2-E1) * D1 / (D1 + D2)

Similarly, the points in the other areas are obtained by linearly interpolating the two change amount limit values on the adjacent hue planes, and the change amount limit value table 12 creation process is terminated.

As described above, according to the second embodiment, the user can specify the smoothing amount in the six hues by further dividing the smoothing amount into the bright part and the dark part, so that the smoothing can be controlled more finely with respect to the color correction table 23. It becomes possible to carry out the conversion processing. Further, when a value larger than 0 is designated as a change amount limit value for a certain region and a change amount limit value 0 is designated for a neighboring region, the change amount limit value larger than 0 is propagated to the neighboring region. Color correction table 23
In the case of the region where it is desired to suppress the fluctuation of the value, it is possible to perform an operation such as fixing the value only in the region.

In the first and second embodiments described above, when the change amount limit value table is set, the change amount limit value in the area between adjacent hues is set with respect to the distance and angle from each grid point. Although an example of linearly changing is described above, this may be changed non-linearly.

In the above-described first and second embodiments, the user specifies the change amount limit value for each of the six hues or for each of the light and dark parts of the six hues.
For example, a method may be used in which the change limit value is specified by further dividing the hue and the lightness, or the change limit value is specified according to the saturation.

<Third Embodiment> The third embodiment of the present invention will be described below.
Will be described. In addition, in the present embodiment, the substantially same configurations as those of the first and second embodiments are designated by the same reference numerals, and detailed description thereof will be omitted.

FIG. 22 is a block diagram showing the arrangement of the image processing apparatus according to this embodiment. The image processing apparatus according to the third embodiment is obtained by adding a preview image creation unit 221 to the image processing apparatus according to the first and second embodiments, and displays the smoothing processing effect of the smoothing unit 25 on a monitor. The feature is that it can be confirmed by.

FIG. 23 is a view showing a basic example of a preview screen displayed on the color monitor 20 which is created by the preview image creating section 221. In this preview screen, an image obtained by converting the original image using the color correction table 23 temporarily smoothed by the temporary smoothing unit 13 on the left is shown on the right after temporary smoothing using the change amount limit value table 12. An image obtained by converting the original image is displayed with reference to the color correction table 23 in which the RGB values of are corrected. Here, the user can specify an arbitrary original image on the UI.

As described above, by displaying the preview screen in which the color correction table after the temporary smoothing and after the change amount limit value is applied is displayed on the image, the effect of the smoothing amount adjustment in each of the above-described embodiments is displayed. Can be easily confirmed on the image display.

<Fourth Embodiment> The fourth embodiment of the present invention will be described below.
Will be described.

In each of the above-described embodiments, the smoothing amount is specified for each predetermined area on the color space. However, in this embodiment, the user can specify the color to be smoothed and the influence range. And The configuration of the image processing apparatus according to the fourth embodiment is similar to that of the third embodiment described above.

FIG. 24 is an example of a user interface in the parameter designating section 10 of the fourth embodiment.
In FIG. 24, 2401 is a correction target RGB value,
The color for which the change amount limit value is specified by smoothing is RGB
It is an item set by coordinates. A change amount limit value 2402 is an item for setting the change amount limit value in the correction target RGB value as the color difference ΔE. Reference numeral 2403 denotes an influence range, which is an item for setting a range of a spherical region centered on the correction target RGB value. When the check box 2404 indicating “Specify RGB values from image” is checked, the preview screen or the original image shown in FIG. 23 is displayed, and the user clicks a point on the image with the mouse to set the correction target RGB. Set the value. Figure 25
Is the set correction target RG in the RGB color space.
It is a conceptual diagram explaining B value and an influence range. In the same figure, 2501 indicates the coordinates of the set correction target RGB values, and a spherical influence range 2502 is set around this correction target RGB value in accordance with the set influence range.

FIG. 26 is a graph showing the relationship between the distance d from the correction target RGB value in the RGB color space and the variation limit value. As shown in FIG. 26, the smoothing unit 25 reduces the change amount limit value as the distance from the correction target RGB value increases, and reduces the change amount limit value at the boundary of the influence range to the minimum smoothed RGB value. to correct. Note that FIG. 26 shows an example in which the change amount limit value changes linearly with respect to the distance from the corrected RGB value, but it may of course be changed non-linearly as shown in FIG. 27, for example. Also, the range of influence 25
As the area 02, for example, an ellipsoidal or rectangular parallelepiped area may be used instead of the spherical area.

As described above, according to this embodiment,
The user can specify the color to be smoothed and the range of influence,
More free control becomes possible. Further, since the color to be smoothed can be selected from the image, it is possible to more intuitively and accurately specify the color to be smoothed.

<Other Embodiments> The present invention is based on the first embodiment described above.
The present invention is not limited to the fourth embodiment, and the following modifications are possible, for example.

In each of the above-described embodiments, the change amount limit value uses the distance in the Lab color space, that is, the color difference ΔE, but it may be defined as the distance in another color space such as the RGB color space.

In each of the above-described embodiments, the smoothing process of the data stored in the color correction table is performed by RGB.
Although it is performed in the color space, it can be performed in other color spaces such as Lab, CMY, and XYZ.

Further, in each of the above-described embodiments, the variation limit value is used as the smoothing condition, but other parameters for controlling the degree of smoothing processing may be used. For example, the coefficient used for the smoothing process may be controlled.

In each of the above-described embodiments, the user manually sets the change amount limit value, but a preset change amount limit value may be used.

Even when the present invention is applied to a system composed of a plurality of devices (for example, host computer, interface device, reader, printer, etc.), a device composed of one device (for example, copying machine, facsimile). Device).

Further, an object of the present invention is to supply a storage medium storing a program code of software for realizing the functions of the above-described embodiments to a system or apparatus, and to supply a computer (or CPU) of the system or apparatus.
Needless to say, this is also achieved by the 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 the program code, for example, a floppy (R) disk, a hard disk, an optical disk, a magneto-optical disk, a CD-RO.
M, CD-R, magnetic tape, non-volatile memory card,
A ROM or the like can be used.

Further, by executing the program code read by the computer, not only the functions of the above-described embodiments are realized, but also the OS (operating system) running on the computer based on the instruction of the program code. It is needless to say that this also includes the case where the above) performs a part 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, It goes without saying that a case where the CPU or the like included in the function expansion board or the function expansion unit performs some or all of the actual processing and the processing realizes the functions of the above-described embodiments is also included.

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, It goes without saying that a case where a CPU or the like included in the function expansion board or the function expansion unit performs some or all of the actual processing and the processing realizes the functions of the above-described embodiments is also included.

[0070]

As described above, according to the present invention,
The smoothing condition can be controlled for each of the plurality of positions in the color space. Therefore, for a position on a certain color space, the pseudo contour can be suppressed by smoothing processing, and for a position on a certain color space, it is possible to prevent the color reproducibility from changing more than necessary. It is possible to improve the sex.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of an image processing apparatus to which a color adjusting apparatus according to an embodiment is applied.

FIG. 2 is a schematic diagram showing a grid point arrangement before color correction processing in an RGB color space.

FIG. 3 is a diagram showing an example of data held in a color correction table.

FIG. 4 is a schematic diagram showing a grid point arrangement after color correction processing in an RGB color space.

FIG. 5 is a block diagram showing a configuration of a color adjustment device according to an embodiment.

FIG. 6 is a diagram showing an example of a UI for designating a smoothing parameter.

FIG. 7 is a flowchart showing a smoothing process.

FIG. 8 is a diagram showing an example of data held in a change amount limit value table.

FIG. 9 is a diagram showing a relationship of colors before, after smoothing processing, and after smoothing processing in an RGB space.

FIG. 10 is W-RGBCMY-B in RGB space.
It is a figure which shows the hue plane of k.

FIG. 11 is a diagram showing a tetrahedral region sandwiched between a WR-Bk hue plane and a W-Y-Bk hue plane.

FIG. 12 is a diagram showing an example of a UI for designating a smoothing parameter in the second embodiment.

FIG. 13 is a flowchart showing a process of creating a change amount limit value table.

FIG. 14 is a diagram showing a line connecting RGBCMY.

FIG. 15 is a diagram showing two representative colors adjacent to W, and twelve faces formed by two representative colors adjacent to each other and Bk.

FIG. 16 is a diagram illustrating a method of calculating a change amount limit value corresponding to a lattice point Ps on the RM-Bk plane.

FIG. 17 is a diagram showing RGBCMY-Gm lines.

FIG. 18 is a W-RGBCMY-Gm plane and Gm-RG.
It is a figure which shows BCMY-Bk.

FIG. 19 is a diagram illustrating a method of calculating a variation limit value corresponding to a lattice point Pi on a Gm-R-Bk plane.

FIG. 20: W-representative colors of two adjacent colors-Gm and Gm
-Representative colors of two adjacent colors-A diagram showing the inside of a tetrahedral region having Bk as a vertex.

FIG. 21 is a diagram illustrating a method of calculating a change amount limit value corresponding to a lattice point Pcb in a tetrahedral area having Gm, C, B, and Bk as vertices.

FIG. 22 is a block diagram showing the configuration of an image processing apparatus to which the color adjusting apparatus according to the embodiment is applied.

FIG. 23 is a diagram showing an example of a preview screen.

FIG. 24 is a diagram showing an example of a UI for designating a smoothing parameter in the third embodiment.

FIG. 25 is a diagram illustrating a smoothing target color and an influence range on an RGB color space.

FIG. 26 is a diagram showing an example of a relationship between a distance from a smoothing target RGB value and a change amount limit value.

FIG. 27 is a diagram showing an example of a relationship between a distance from a smoothing target RGB value and a variation limit value.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Shigetasu Nagoshi             Kyano, 3-30-2 Shimomaruko, Ota-ku, Tokyo             Within the corporation F term (reference) 5B057 CA01 CA08 CA16 CB01 CB08                       CB16 CE05 CE17 CE18 CH07                 5C077 LL01 LL02 MP08 PP02 PP32                       PP33 PP37 PP47 PP51 PQ12                       PQ23 TT02                 5C079 HB01 HB02 HB12 LA10 LA14                       LB02 MA04 MA11 NA02 NA03                       PA03

Claims (18)

[Claims] 1. A color correction table creating method for creating a color correction table by performing smoothing, wherein smoothing conditions corresponding to a plurality of positions in a color space are set and smoothing is performed in accordance with the smoothing conditions. A method for creating a color correction table characterized by the above. 2. The color correction table creating method according to claim 1, wherein the smoothing condition is a color change amount before and after smoothing at a plurality of positions in the color space. 3. The color correction table creating method according to claim 2, wherein the color change amount is a color difference. 4. The color correction table creating method according to claim 2, wherein the color change amount is obtained based on each colorimetric value before and after the smoothing. 5. The color correction table creating method according to claim 1, wherein the plurality of positions are positions on the color space corresponding to a plurality of representative colors. 6. The input values to the color correction table are RGB
The representative colors are red, green, blue,
The color correction table creating method according to claim 5, wherein the color correction table is cyan, magenta, and yellow. 7. The color correction table creating method according to claim 1, wherein the plurality of positions are respective grid points on the color space. 8. The method of creating a color correction table according to claim 7, wherein the smoothing condition for each grid point of the color correction table is obtained based on the smoothing condition corresponding to the plurality of representative colors. 9. The color correction table creating method according to claim 8, wherein the smoothing condition for each grid point is a limit value of a color change amount before and after smoothing. 10. The smoothing condition setting for each grid point is based on the smoothing condition for each grid point in the color correction table, between white and each of the plurality of representative colors, and each of the plurality of representative colors. The limit value of the grid points existing between the black and the black is determined, and based on the smoothing condition for each grid point of the color correction table, it exists on the hue plane composed of the white, the black, and the plurality of representative colors. To determine the limit value of the grid point to
10. The method for creating a color correction table according to claim 9, wherein a limit value of grid points existing between two hue planes is determined. 11. The color correction table creating method according to claim 1, wherein smoothing is not performed at grid points on the achromatic color axis in the color correction table. 12. A color correction table creating apparatus for creating a color correction table by performing smoothing, means for setting smoothing conditions corresponding to a plurality of positions in a color space, and smoothing according to the smoothing conditions. Means for doing
A color correction table creating device comprising: 13. A control program for realizing the color correction table creating method according to claim 1 by a computer. 14. A storage medium for storing the control program according to claim 11. 15. The method of creating a color correction table according to claim 9, wherein the limit value changes linearly or non-linearly according to a distance or an angle from the grid point. 16. The table creating method according to claim 1, wherein the smoothed image is output to a preview screen creating unit that creates a preview screen displaying the result of the smoothing. 17. The table creating method according to claim 1, wherein the plurality of positions are determined by an instruction of an operator. 18. The table creating method according to claim 1, wherein the range of influence of the smoothing is determined by an operator's instruction.