JP2001136401A - Color separated image correction method, chart ink jet printer, color separated image correction device and recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a method for properly utilizing a specific color over a color gamut wider than a conventional CMYK color gamut that is in combination with a color reproduction method within the conventional CMYK color gamut. SOLUTION: Relating to the color separated image correction device that corrects a color separated image electric signal and reproduces an object color by using cyan C, magenta M, yellow Y, high saturation color material and black K, it is provided with processing means 20, 30 that combine a plurality of sets of color gamut produced by the black K and the three colors to obtain the combination of color materials used actually, and an instruction means 60 that received an instruction of at least either of how to use the specific color and the setting method of the black K so as to obtain combinations of the color materials used for the image output.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color separation image correction method, a chart, an ink jet printer, a color separation image correction device, and a recording medium, and more particularly, to a color for reproducing a target color in an image output device using a high chroma color material. It relates to improvement in determining the material.

[0002]

2. Description of the Related Art In a printer using a so-called high-saturation color material (special color) other than the usual color materials such as yellow Y, magenta M, cyan C, and sum K, the number of color materials is large and colors for reproducing a target color are used. There was a problem that it was difficult to determine the proportion of wood.

Further, there has been a demand for a method capable of estimating the characteristics of a printer having a large number of color materials with the number of measurements within a practical range. In addition, it is easy to increase the number of color materials in an ink jet printer, and a method that can obtain many color materials by a systematic method has been desired.

(1) The technique described in Japanese Patent Application No. 5-36814 discloses a method for correcting a color separation image of a printer using CMYK as a color material. The prior color gamut is represented by three colors including K. In this case, a combination of CMYK with respect to a target color is obtained by dividing the image into dimensional color gamuts and adding restrictions. This is because there is no combination that uniquely reproduces an arbitrary color while the four colors of CMYK remain.

(2) A description of the color gamut of a printer using a combination of orange O and green G as a high-saturation color material (special color) in addition to the four colors of CMYK is described as "HIFI Color Printing within a Color Manager".
t System '' M. Mahy and DDBear, The Fifth Color Ima
ging Conference: Color Science, Systems, and Appli
cations, pp. 277-283 (1997). In this paper, an analytical model is used to estimate the colorimetric characteristics.

(3) Japanese Patent Application Laid-Open No. 2-86388 discloses that when CMYK is used as a coloring material, the number of measurement points is reduced as the amount of K increases.

(4) Regarding a method for adjusting colorimetry in the case of a three-color printer, see "Colorimetric calibration in
electronic imaging devices using a look-up-table m
odeland interpolations '' Po-Chieh Hung, Journal of
Electronic Imaging 2 (1), 53-61 (1993).

(5) In addition, regarding the method of outputting the entire color gamut composed of the color gamut of CMYK and the color gamut of the other three colors as much as possible using a special color as much as possible and using as little as possible a special color, A proposal is made as Japanese Patent Application No. 10-196004.

(6) In order to limit the amount of color material, a method of determining the upper limit of an actual color material using a function of N inputs and N outputs is disclosed in Japanese Patent Application No. Hei 10-196005.
No. is proposed.

(7) Further, a combination of CMYK and a special color is used for a minimum HiFi color (Min HFC) and a maximum H.
PC Hung Colo for iFi color (Max HFC)
rimetric Calibration for High Quality Color Printe
rs, PPIC / JH: Pan-Pacific Imaging Conference / Japan
Hardcopy '98 pp.147-150 (1998).

[0011]

The prior arts described above have the following problems, respectively. Above (1)
In the method of (1), the usable object is limited to a printer of four colors, and it is impossible to cope with a case where a high-saturation color material (special color) other than CMY is used.

In the method (2), CMYKOG
Since any four colors are taken out of the above and the color gamut is calculated and the color material to be used is determined, the execution conditions are not disclosed even though the candidates become complicated. In addition, since the estimation of the colorimetric characteristics uses an analysis model, only a clear area modulation type such as offset printing is targeted, and it cannot be practically applied to an ink jet printer or the like. .

In the method (3), a case of a four-color printer is described. However, if the number of color materials is increased, the number of measurement points is increased, which is not practical. In the above-mentioned method (4), an example of a three-color printer is described. However, if the number of color materials is increased, the number of measurement points for performing colorimetric adjustment increases, which is not practical.

In the method (5), CMY
Other than K, the color gamut was combined with the three color gamut, and some color gamut could not be used. As for the method (6), a method of applying the method to a combination of CMYK and a spot color is not specifically described.

In the method (7), CMY
Combination of K, RMYK, GCYK, BMCK, or RYK, YGK, GCK, CBK, BMK, MR
Min HFC, Max each limited to the combination of K,
HFC was released, but could not freely choose how to use K.

That is, from the above, the color reproduction cannot be simplified by the color reproduction using the special color. The color material amount can be freely limited by the color reproduction using the special color. None ・ A large number of colorimetric points were required for characterization ・ Color material could not be set in consideration of remaining color material in color reproduction using special colors ・ Durable Ink-jet printers using pigments had a narrow color gamut.Use of light-colored inks for each color could expand the color gamut, but the problem was that the head became large and the amount of calculation for color reproduction was enormous. Has occurred.

An object of the present invention is to combine a conventional color reproduction method in the CMYK color gamut to realize an appropriate special color utilization method for a wider color gamut.

[0018]

The present invention for solving the above problems is as described below. (1) The invention according to claim 1 corrects a color separation image signal input as an electric signal and reproduces a target color using cyan C, magenta M, yellow Y, a high-saturation color material (special color) and Sumi K. A color separation image correction method for
And a step of combining a plurality of color gamuts generated by the three chromatic colors to obtain a combination of actually used color materials, and a step of providing one or both of a special color use method and a K setting method. And a color separation image correcting method for obtaining a combination of color materials used for image output.

According to a twentieth aspect of the present invention, the target color is changed to cyan C, magenta M, yellow Y, a high-saturation color material, and a
A color separation image correction device for reproducing using
K and a plurality of color gamut generated by three chromatic colors are combined to obtain a combination of actually used color materials, and an instruction on at least one of a special color use method and a K setting method is provided. A color separation image correction device, comprising: a designating means provided to obtain a combination of color materials used for image output.

In the present invention, the color gamut in the case of using a special color is decomposed into a color gamut of a combination of four color gamuts, so that a method for a conventional four-color printer can be used.
By giving the setting of K to each color gamut or the setting of the method of using the special color, the degree of freedom of the combination of the color materials can be increased.

(2) The invention according to claim 2 is the color separation image correcting method according to claim 1, wherein the generated color gamut includes a CMYK color gamut. The color separation image correcting apparatus according to claim 20, wherein the color gamut generated by the processing means includes a CMYK color gamut.

According to the present invention, in addition to the above (1), it is possible to create a color gamut that cannot be reproduced only by using a color gamut using a special color, and it is also possible to use a conventional low-cost CMYK color material. .

(3) The invention according to claim 3 is characterized in that the generated color gamut includes a color gamut formed by a combination of at least one spot color and two other colors. Item 10 is a color separation image correcting method according to Item 1.

According to a twenty-second aspect of the present invention, the color gamut generated by the processing means includes a color gamut formed by a combination of at least one spot color and two other colors. Item 20. A color separation image correcting apparatus according to item 20.

In the present invention, in addition to the above (1), CMY
The same colorimetric points as in the K color gamut can be supplied, and colorimetry can be simplified. (4) The invention according to claim 4 is characterized in that the generated color gamut includes a color gamut formed by a combination of at least two spot colors and one other color.
It is a color separation image correction method described above.

According to a twenty-third aspect of the present invention, the color gamut generated by the processing means includes a color gamut based on a combination of at least two spot colors and one other color. Item 20. A color separation image correcting apparatus according to item 20.

According to the present invention, in addition to the above (1), it is possible to realize an efficient combination capable of reproducing colors near high brightness and high saturation. (5) The color separation image correcting method according to any one of claims 1 to 4, wherein the invention according to claim 5 includes a step of limiting a color material amount.

According to a twenty-fourth aspect of the present invention, in the color separation image correcting apparatus according to any one of the twentieth to twenty-third aspects, the processing means has a means for limiting a color material amount. is there.

According to the present invention, in addition to the above (1) to (4), the color material amount can be limited, so that the color material amount can be limited in accordance with the maximum color material amount of the printer or the image receiving medium. (6) The invention according to claim 6 is a method for setting a color material,
3. The color separation image correcting method according to claim 2, wherein a usage of K near gray and a usage of a special color near high saturation can be designated.

According to a twenty-fifth aspect of the present invention, as the color material setting method specified by the specifying means, it is possible to specify how to use K near gray and how to use a special color near high saturation. 22. A color separation image correcting apparatus according to claim 21, wherein:

According to the present invention, the color material can be freely set. That is, since the usage of K near gray can be designated, gray can be stabilized. In addition, since the usage of a spot color near high saturation can be specified, the use of the spot color can be reduced in view of cost. For this reason, usages such as Max Black and Min HFC are also possible.

(7) The invention according to claim 7 is provided with a plurality of color conversion tables created according to claim 6,
7. The color separation image correcting method according to claim 6, wherein switching is performed according to a remaining amount of the color material.

According to a twenty-sixth aspect of the present invention, the processing means includes a plurality of color conversion tables created by the processing of the twenty-fifth aspect, and switches according to the remaining amount of the color material.
26. The color separation image correcting apparatus according to claim 25, wherein:

According to the present invention, it is possible to change the efficient use of the coloring material depending on the remaining amount of the coloring material. (8) The invention according to claim 8 is provided with a plurality of color conversion tables created according to claim 6, wherein the color conversion table is switched according to the type of picture of the input color separation image signal. It is a color separation image correction method described above.

According to a twenty-seventh aspect of the present invention, the processing means includes a plurality of color conversion tables created according to the twenty-fifth aspect, and switches according to the type of picture of the input color separation image signal. 26. A color separation image correcting apparatus according to claim 25.

According to the present invention, it is possible to change the efficient use of the color material in accordance with the pattern of the input color separation image signal. (9) The invention according to claim 9, wherein smoothing is performed on the color conversion table generated according to any one of claims 1 to 6. This is a decomposition image correction method.

According to a twenty-eighth aspect of the present invention, the processing means performs smoothing on the color conversion table generated by the processing of the twentieth to twenty-fifth aspects. A color separation image correcting apparatus according to any one of the above.

According to the present invention, it is possible to reduce an abrupt change in the amount of color material at a connection portion between color gamuts, and to suppress the occurrence of a false contour due to a change in a printer. (10) The color separation image correcting method according to the ninth aspect, wherein the error generated by the smoothing is corrected by another color conversion table.

The invention according to claim 29 is the color separation image correcting apparatus according to claim 28, wherein said processing means corrects an error generated by smoothing using another color conversion table.

According to the present invention, the color error due to the smoothing is adjusted again by printing, so that the color can be reproduced smoothly and with less colorimetric error. (11) An invention according to claim 11 is a colorimetric chart, wherein the chart is created by outputting a combination of colors produced by the color separation image correcting method according to any one of claims 1 to 5. It is a characteristic chart.

According to the present invention, a chart utilizing a special color can be created by expanding the chart for four colors, so that a color measurement method for four colors can be used. (12) The twelfth aspect of the present invention is a colorimetric chart, which is an output of a combination of colors produced by the color separation image correcting method according to any one of the first to fifth aspects, wherein the colors are duplicated. It is a chart characterized by being created excluding a part.

According to the present invention, not only can a chart using a special color be created by expanding the chart for four colors, but also because the overlapping portion is excluded, the colorimetry can be simplified.

(13) According to the thirteenth aspect of the present invention, the color separation image signal input as an electric signal is corrected so that the target colors are cyan C, magenta M, yellow Y, a high-saturation color material (special color) and a summit K. It is a colorimetric chart to be reproduced by using, and is characterized by being created without overlapping portions.

In the present invention, the colorimetry can be simplified because the overlapping portion is excluded. (14) According to the fourteenth aspect of the present invention, the target color is reproduced using cyan C, magenta M, yellow Y, a high-saturation color material (special color) and Sumi K by correcting the color separation image signal input as an electric signal. A chart for colorimetry,
This chart is characterized in that a chart including a spot color has fewer color charts than a chart not including a spot color.

According to the present invention, the colorimetric measurement can be simplified because there is a portion where the number of color charts is smaller in the chart including the spot color than in the chart not including the spot color. (15) An ink jet printer according to a fifteenth aspect of the present invention is adjusted by the color separation image correcting method according to any one of the first to tenth aspects.

The present invention can be realized by providing a head for a special color in addition to CMYK, and stable color reproduction can be performed. (16) The ink-jet printer according to claim 16, wherein the ink-jet printer uses a coloring material made of a pigment.

According to the present invention, it is possible to reproduce color in a sufficient color gamut even if a pigment having durability but having a narrow color gamut is used. (17) The ink jet printer according to claim 15, wherein at least two types of color materials are used for K.

According to the present invention, by adding the minimum amount of ink and head, it is possible to reduce the rough feeling in the vicinity of gray which is most noticeable. (18) The ink jet printer according to claim 17, wherein the ink is adjusted to use K as much as possible.

According to the present invention, by adding the minimum amount of ink and head, it is possible to stably reduce the roughness in the vicinity of gray which is most noticeable. In addition, it is possible to use a minimum of special colors for a wide color gamut.

(19) According to a nineteenth aspect of the present invention, in parallel with the execution of the color separation image correcting method, the color coordinates after color gamut mapping are held, and the color coordinates of another device for reproducing the color coordinates are stored. 11. The color separation image correcting method according to claim 1, wherein a combination of color material amounts is obtained.

According to the present invention, it is possible to create a proof table without decomposing into a color for a color material, and it is possible to reduce the amount of calculation at that time. (20) The invention according to claim 30 is to correct a color separation image signal input as an electric signal to reproduce a target color by using cyan C, magenta M, yellow Y, a high chroma color material (special color) and Sumi K. A computer-readable recording medium on which a color separation image correction processing program for performing a color separation image correction process is stored.
Combining a plurality of color gamuts generated by the three chromatic colors to determine a combination of actually used color materials; and providing one or both of a special color use method and a K setting method. A computer-readable recording medium characterized by comprising:

In the present invention, the color gamut in the case where a special color is used is decomposed into a color gamut of a combination of four color gamuts, so that a method for a conventional four-color printer can be used.
By giving the setting of K to each color gamut or the setting of the method of using the special color, the degree of freedom of the combination of the color materials can be increased.

[0053]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A color separation image correction method, chart, ink jet printer, color separation image correction device and recording medium according to an embodiment of the present invention will be described with reference to the drawings.

First, with reference to FIG. 1, a description will be given of an entire color-separated image correcting apparatus 1 for executing the color-separated image correcting method according to the embodiment of the present invention. In the embodiment shown here, three colors of red R, green G, and blue B are used as high-saturation color materials (special colors) in addition to cyan C, magenta M, yellow Y, and sum K.
Note that the high-saturation color material is not limited to the colors shown here and the number of colors.

Here, reference numeral 10 denotes an address signal forming means for forming an address signal corresponding to an input level for each of three types of input signals supplied from the outside, and each color (each component) of the input signal. Each of them is configured by lookup tables 11 to 13. It should be noted that a 1-bit distribution signal is supplied to each of the lookup tables 11 to 13 from the controller 50 as control means.

The three types of input signals here are CMY
In addition to color separation image signals such as RGB and RGB, L * a * b * and XYZ may be used. A color reproduction information storage means 20 divides a color space formed by three types of input signals input for color reproduction into a plurality of space areas, and stores color reproduction information for a combination in the space areas. I have.
Here, three types of input signals are converted to CMY including three special colors.
To output as KRGB total 7 color signals, CMYKR
It is configured by lookup tables 21 to 27 corresponding to GB.

The weighting coefficient storage means 25 stores weighting information for each of a plurality of pieces of color reproduction information selected from the color reproduction information storage means 20 based on the input color separation image signal. Output the weight coefficient.

Numeral 30 denotes processing means comprising a multiplying means and a dividing means. The processing means 30 multiplies the color reproduction information from the color reproduction information storage means 20 by the weight coefficient from the weight coefficient storage means 25, and accumulates the value. By doing so, each of the CMYKRGB corrected color separation image signals to be finally obtained is obtained. Therefore, the multipliers 31a to 37a
And accumulators 31b to 37b.

An output means 40 latches each of the corrected color separation image signals (cumulative calculation power) from the processing means 30.
Latched by 1 to 47 and output. The latch pulse required at this time is generated by the controller 50. The user's instruction is input to the controller 50 via the instruction means 60.

Here, as a method of obtaining data to be stored in the color reproduction information storage means 20 of FIG.
A division method of selecting a proper three or four colors from the colors to form a plurality of divided color gamuts, and reproducing colors using a combined color gamut obtained by combining these is used.

In this case, even if the same color is reproduced, a combination that reproduces as much as possible using a special color is used as the maximum color.
m HFC (hereinafter referred to as Max HFC) and a combination that reproduces as little as possible using special colors is called Minimum HFC (hereinafter referred to as Min HFC).
Call. This is a four-color reproduction problem, a known technique.
Maximum Black (hereinafter, Max Black) and Minimum Black
(Hereinafter referred to as Max Black).

Color reproduction of spot color: A typical method of selecting a spot color is to add a primary color of a secondary color such as BGR in addition to CMYK. As the number of colors increases, there is a problem that the number of colorimetric points (characterization data) for obtaining colorimetric characteristics increases exponentially. When the special color is BGR, the total number of colors is seven.
Requires a multiplied colorimetric point.

For example, if there are intermediate levels of 5 points for each color, then ⁷ = 78125 for 7 colors, which is not a practical colorimetric point even if an automatic measuring device is used. Further, in this case, a combination using all colors at the same time is included. However, when one color of each color is 100%, using a total ink amount of 700 is not practical because of a problem such as a drying time of the recording paper. Absent.

In the specification of the present application, the expression “M ^N ” means that M is the Nth power. Therefore, a divided color gamut is created as a combination of up to four colors,
It is considered that the entire color gamut is configured by this combination. However, it is known that even if the maximum ink amount is 400%, it is still too large in consideration of drying and ink absorption amount. 3 for printing
It is said that the ink jet printer uses a medium having a small absorption capacity, ie, about 200%.
Since the color material amount limitation can be used for four colors including K, a division method based on a combination of K and three chromatic colors will be considered.

Assuming that there are a total of N colors including the achromatic color K, the number of combinations M by the division method is represented by M = ((N−1)!) / ((N−4)! 3!).

When BGR is used as a special color, N = 7
Thus, there are 20 divided color gamuts. Among them, C
The one that can reproduce the color gamut near high brightness by the MYK color gamut and other combinations (referred to as a hi-fi color gamut) is YRM
K, YGCK, MBCK, RKGK, GCBK, BMR
K, from each divided color gamut.

In order to clarify the color gamut of a special color, a color material having the reflectance of the CMYK primary colors of printing and the reflectance of the BGR primary colors of the CRT is assumed. Calculates the characteristics of the printer using the spot color as C
Examination using each color material of MYKRGB revealed the following.

Here, the combination that can secure the maximum color gamut when combined is as follows: a composite color gamut A obtained by combining YRMK, YGCK, and MBCK divided color gamuts; and a division of RKGK, GCBK, and BMRK. It was clear that these were two, a synthesized color gamut B obtained by synthesizing color gamut.

These YRMK, YGCK, MBCK
Color gamut A obtained by synthesizing the divided color gamut of RKGK, G
Synthetic color gamut B obtained by synthesizing the divided color gamut of CBK and BMRK
In the above, it was found that a high lightness color gamut could be reproduced in the three color gamut, but a low lightness color gamut could not be completely reproduced. In order to reproduce the entire color gamut, more divided color gamuts are required, but since the purpose of using special colors is to expand the color gamut of high lightness and high saturation parts and the slight difference in dark areas, A description will be given of a composite color gamut using the three color gamuts.

Next, in deciding which of the two types of combined gamut to use, the following characteristics of the divided gamut are taken into consideration: When specifying Min Black in the hi-fi gamut, which divided gamut is specified Also degenerate (to be described later), so that the color gamut is only in the vicinity of the high chroma, and thus requires the CMYK color gamut of low chroma. The combined color gamut A has the same boundary as the CMYK color gamut when Min HFC is used. For example, there is a surface having four vertices of WYM-YM, while the combination of the combined color gamut B is used. There is no combination corresponding to this aspect. The composite color gamut B has fewer color patches in common with the CMYK color gamut than the composite color gamut A, so it is difficult to reduce the number of colorimetric points.

From the above properties, a combined color gamut A in which three color gamuts of four colors using spot colors are combined, and CMY
It is desirable to use a combined color gamut that can be formed by a total of four color gamuts in combination with the K color gamut.

Procedure: Here, Max Black / Min
The procedure of spot color reproduction without limiting Black and Max HFC / Min HFC is shown below.

Step 1: First, a chart (color patch) for the composite color gamut A is created. Here, the basic CMYK color gamut, YRMK, YGC
A chart composed of a combined color gamut A obtained by combining the divided color gamuts of K and MBCK is created. Here, FIG.
FIG. 3 shows a YRMK chart, FIG. 4 shows a YGCK chart, and FIG. 5 shows an MBCK chart.
FIG. By using such a chart, a chart using a special color can be created by extending the conventional chart for four colors, so that a color measurement method for four colors can be used.

Step 2: Colorimetric values are obtained for grid points in the three color gamuts of the CMYK color gamut and the composite color gamut A. Here, the number of grid points in each color gamut is 312 (= 5 ³ +5 ³ +3 ³ +3 ³ +2
³ ) Use degree. That is, since the number of measurement points is large at all the grid points in the charts of FIGS.
With respect to the chart (3), 312 colorimetric values are obtained as shown in FIG. The same applies to the other color gamuts shown in FIGS.

To reduce the number of measurement points, the number of color steps (color patches) is reduced as the color becomes darker (see FIG. 6). Overlapping color patches are deleted (not shown) between the divided gamut charts (FIGS. 2 to 5). Reduce the number of steps when increasing features. For example, in FIG. 3, R has 5 steps (R = 0,64,128,192,255).
It is reduced to steps (R = 0,128,255) (see FIG. 7).

In this case, it is possible to not only create a chart using a special color by expanding the chart for four colors, but also eliminate overlapping portions and reduce the number of special color steps, thereby simplifying color measurement. can do.

Step 3: Interpolate each data,
LUT model for 4 color solids (LU with LCC output, coordinates of uniform color space with n ⁴ system value inputs)
T) is created.

[0078] Step 4: (the system value of m ³ input, with LCC output) LUT model of the device to be a target to create a.

Step 5: Each LCC value of the target device is searched for four color gamuts, and the outermost value of a compression straight line (radiation from the L * axis) for performing color gamut mapping is obtained.

Step 6: According to the color gamut mapping method,
A mapping destination LCC value corresponding to the LCC value of the target horizontal unit is determined.

Step 7: A combination of primary color amounts corresponding to each color gamut (hereinafter referred to as primary color amounts) is obtained. At the same time, the inside and outside of the color gamut are determined.

Step 8: (a) In case of Min HFC: If the color is in the CMYK color gamut,
This primary color amount is given. If the color is out of the CMYK color gamut, it must be in any of the hi-fi color gamut. (B) In the case of Max HFC: Select a hi-fi color gamut that falls within the color gamut and give its chromaticity point. Any hi-f in the shadow part
If it does not belong to the i color gamut, the primary color amount of the CMYK color gamut is given. The calculation in each divided color gamut is Min Black, Max B
According to the designation of lack, the primary color amount is calculated.

Step 9: This is performed for all the lattice points of the LUT model of the target device, and a device link profile for creating a relationship from the target device to the output device is created.

The color reproduction information for spot color reproduction obtained as described in the above steps 1 to 9 is stored in the color reproduction information storage means 20 (look-up table 2).
1 to 27).

By performing the above procedure, the color gamut in the case where a special color is used is decomposed into a color gamut of a combination of four color gamuts, so that a conventional method for a four-color printer can be used. . By giving the setting of K to each color gamut or the setting of the method of using the special color, the degree of freedom of the combination of the color materials can be increased.

As described above, by including both a color gamut using a special color and a conventional CMYK color gamut, a color gamut that cannot be reproduced only by using a color gamut using a special color can be created. In addition, it becomes possible to use the conventional low-cost CMYK color material.

Note that the color gamut generated in the present embodiment includes a color gamut formed by a combination of at least one spot color and the other two colors (the composite color gamut A described above).
The same colorimetric points as in the CMYK color gamut can be supplied, and colorimetry can be simplified.

Further, the color gamut generated in another embodiment includes a color gamut formed by a combination of at least two special colors and one other color (the above-described combined color gamut B). An efficient combination that can reproduce colors near high brightness and high saturation can be realized.

Further, in the present embodiment, the provision of the step or means for limiting the amount of the color material allows the amount of the color material to be limited, and the limitation of the amount of the color material in accordance with the maximum amount of the color material of the printer or the image receiving medium. Becomes possible.

Further, the present embodiment is characterized in that the use of K near gray and the use of a special color near high saturation can be designated as the color material setting method. In other words, the usage of K can be selected for each of the CMYK color gamut and each hi-fi color gamut, and further, the CMYK color gamut, hi-f
There are variations depending on how the i color gamut is used.

That is, a method of using K in the CMYK color gamut (Max Black / Min Black
/ Smoothest Black) ・ How to use K for each hi-fi color gamut (Max Black / Min Blac)
k)-There are many options for combining the above color gamuts (Max HFC / Min HFC) by combining them. Practically, handling of K near gray,
It may also be sufficient to provide options for each of the treatments of the spot color near high saturation. FIG. 8 summarizes the handling options.

Here, patterns 1 to 4 can be considered by the user's designation via the instruction means 60 (see FIG. 1). In this embodiment, the color material can be freely set. That is, since the usage of K near gray can be designated, gray can be stabilized. In addition, since the usage of a spot color near high saturation can be specified, the use of the spot color can be reduced in view of cost. For this reason, usages such as Max Black and Min HFC are also possible.

Further, in the embodiment of the present invention, a plurality of color conversion tables (LUTs in FIG. 1) created for setting the color materials as described above are provided, and are switched according to the remaining amount of the color materials. , Is characterized. For example, if two types of R1 (first red) and R2 (second red) are used,
Two color solids of YR1MK and YR2MK are generated. At this time, since the two color solids obviously overlap, it is necessary to determine which color gamut to use when reproducing the color coordinates of that part. In this case, a priority is assigned to one of them, and if both are included in the color solid, a combination of colors having a higher priority is assigned. Practically, it is conceivable to use a method in which the color material price is prioritized, or two types of LUTs with different priorities are created and switched according to the remaining amount of the color material. As a result, it is possible to change the efficient use of the coloring material according to the remaining amount of the coloring material.

Further, in the embodiment of the present invention, a plurality of color conversion tables (LUTs in FIG. 1) created for setting the above color materials are provided, and the inputted color separation image signal is provided. It is also possible to switch according to the type of picture. Here, the “picture” means the size of the high chroma area included in the image. For example, if there are many gray components, use CMYK color materials,
If the color saturation is high, a special color material is used. As a result, it is possible to change the efficient use of the color material in accordance with the pattern of the input color separation image signal.

Further, in the embodiment of the present invention, a plurality of color conversion tables (LUTs in FIG. 1) created for setting the above color materials are provided, and smoothing is performed. And

That is, in this method, the problem of the division method remains as it is, and a smooth change in the amount of primary colors at the combined color gamut boundary is not guaranteed. In the case of four colors, all characteristics could be measured, so that the connection between color solids could be made smooth while guaranteeing the target color by the Smoothest Black method. However, in the case of hi-fi printing, since the number of color materials is too large to measure all characteristics, the target color cannot be maintained.

First, the divided CMYK color gamut and hi-f
Consider the application of Smoothest Black in the i gamut. CMYK
Although Smoothest Black can be applied to the color gamut, it cannot be applied within the hi-fi color gamut due to the following problem. That is, in the hi-fi color gamut, Min B
The color gamut volume during lack is greatly reduced.

FIG. 9 shows this situation. In the CMYK color gamut, since the color gamut is convex, both Min Black and Max Black have the same volume (FIGS. 9A and 9B), but the color gamut shape is concave
The same volume is not guaranteed in the hi-fi color gamut (Fig. 9 (b)
(C)).

For this reason, although Smoothest Black can be applied to the CMYK color gamut at the time of Min HFC, smooth connection is not guaranteed in the hi-fi color gamut and between the CMYK color gamut.
Therefore, the color change when the completed LUT was simply directly smoothed was examined. Then, this output is averaged with respect to the color conversion table by the following equation.

[0100]

(Equation 1)

Here, S is the output of the LUT and CMYKBG
R. k, j, i are the coordinates of the grid of the LUT, and the range is 0 to L-1 (L is the number of grid points of the LUT).
However, when k + kk, j + jj, i + ii is less than 0 or exceeds L-1, data in the axial direction does not participate as averaged data. This prevents the color gamut from being reduced.

From the output of the LUT averaged by the above equation, the color coordinates are calculated using the above-described printer model.
Compare with color coordinates calculated from original LUT. FIG. 10 shows the number of times of averaging, changes in the primary color amounts of the white-black, cyan-red magenta-green, and yellow-blue gradations (only yellow-blue) and the increase in error due to smoothing.

Looking at this, a large error has occurred partially. It is considered that the reason for this is that an erroneous color was originally calculated in the vicinity of blue, and that the smoothing had the effect of eliminating this erroneous color. However, excluding this singular point, in the printer system, when a maximum color difference of about 5 is allowed, the change in the primary color amount becomes clearly smooth as shown in FIG. If it is necessary to correct this error, the accuracy can be improved by using the LUT created here as a “connection function” and reprinting to create a fine adjustment LUT. In such an embodiment,
Sudden change in color material amount at the connection between color gamuts is reduced,
It is possible to suppress the occurrence of the false contour due to the fluctuation of the printer.

Here, the “connection function” is the one shown in FIG.
As shown in (1), a connection function with a small number of variables is determined in advance to construct an imaginary three-color or four-color printer, to which a conventional color reproduction method is applied.

That is, in the example shown in FIG. 12, reference numeral 100 denotes a final profile for converting an input signal (L * a * b *, RGB, XYZ, etc.) into a corrected color separation image signal (CMYKRGB). Yes, a profile holding unit 110 that holds a profile as a conversion table,
And an LUT 120 having a connection function. Also,
200 is an N-color printer, here CMYKRG
The image is formed using the seven color materials B. And
The connection function 120 and the printer 200 constitute a virtual printer 300.

<Other Embodiments> Application to Inkjet Printer: Providing a special color head in addition to CMYK by providing the above-described color separation image correction method or color separation image correction apparatus to an ink jet printer. And stable color reproduction can be performed.

Further, in the ink jet printer to which the present invention is applied, it is preferable to use a coloring material made of a pigment.
In this case, even if a pigment having durability but having a narrow color gamut is used, color reproduction can be performed in a sufficient color gamut.

In the ink jet printer to which the present invention is applied, it is preferable to use at least two types of color materials for K. By doing so, it is possible to reduce the feeling of roughness near gray which is most noticeable by adding a minimum amount of ink and head.
Also, in such an ink jet printer, MaxBla
It is preferable that K is adjusted to use K as much as possible, such as ck. This makes it possible to stably reduce the roughness near gray which is most noticeable by adding a minimum amount of ink and head. In addition, it is possible to use a minimum of special colors for a wide color gamut. Further, the same effect can be obtained by using two types of color materials for a high-density spot color (for example, B) in addition to or instead of K.

Application to Color Proof: In the present invention, the color coordinates after color gamut mapping are held in parallel with the execution of the above-described color separation image correction processing, and the color coordinates are reproduced. It is also preferable to determine the combination of the color material amounts of the devices (CRT display and printer). According to this method, it is possible to create a proof table without separating the color into colors for color materials, and it is possible to reduce the amount of calculation at that time. For example, conventionally, L * a * b * is converted into data of N colors (for example, 7 colors), and data of three colors of RGB is further obtained from the data of N colors. L * 'a *' b * 'generated by performing color gamut mapping of * a * b * is held, and RGB values may be obtained from the L *' a * 'b *' for a CRT display.

Application to processing program: The above-described color separation image correction processing program, that is, the color separation image signal input as an electric signal is corrected to change the target color to cyan C, magenta M, yellow Y, A color separation image correction processing program for reproducing using a high saturation color material (special color) and Sumi K, wherein the color separation image correction processing program includes a plurality of colors generated by K and three chromatic colors. A step of obtaining a combination of actually used color materials by combining gamut and a method of using a special color
And a step in which either or both of the above setting methods are given also constitute a part of the present invention.

[0111]

According to the present invention described in detail above, the following effects can be obtained. (1) In the first and twentieth aspects of the present invention, a method for a conventional four-color printer is used to decompose a color gamut when a special color is used into a color gamut of a combination of four color gamuts. Can be. By giving the setting of K to each color gamut or the setting of the method of using the special color, the degree of freedom of the combination of the color materials can be increased.

(2) According to the second and twenty-first aspects of the present invention, it is possible to create a color gamut that cannot be reproduced only by using a color gamut using a special color.
Color materials can be used.

(3) According to the third and twenty-second aspects of the present invention, the same colorimetric points as those in the CMYK color gamut can be supplied, and the colorimetry can be simplified. (4) According to the inventions described in claims 4 and 23, an efficient combination capable of reproducing colors near high brightness and high saturation can be realized.

(5) According to the fifth and twenty-fourth aspects of the present invention, the color material amount can be limited, so that the color material amount can be limited in accordance with the maximum color material amount of the printer or the image receiving medium. (6) According to the inventions described in claims 6 and 25, the color material can be freely set. That is, K around gray
Can be specified, so that gray can be stabilized. In addition, since the usage of a spot color near high saturation can be specified, the use of the spot color can be reduced in view of cost. For this reason, MaxBlack and Min HF
You can also use it as C.

(7) According to the seventh and twenty-sixth aspects of the present invention, it is possible to change the efficient use of the coloring material depending on the remaining amount of the coloring material. (8) According to the invention of claims 8 and 27, it is possible to change the efficient use of the color material according to the picture of the input color separation image signal.

(9) According to the ninth and twenty-eighth aspects of the present invention, it is possible to reduce a sudden change in the amount of color material at a connection portion between color gamuts and to suppress the occurrence of a false contour due to a change in a printer. Will be possible.

(10) According to the tenth and twenty-ninth aspects of the present invention, the color error due to the smoothing is adjusted again by printing, so that the color can be reproduced smoothly and with less colorimetric error.

(11) According to the eleventh aspect, a chart utilizing a special color can be created by expanding the chart for four colors, so that a color measurement method for four colors can be used.

(12) According to the twelfth aspect of the present invention, not only can a chart using a special color be created by expanding the chart for four colors, but also the overlapping portion is removed, so that the colorimetry is simplified. can do.

(13) In the invention according to the thirteenth aspect, since the overlapping portion is excluded, the colorimetry can be simplified. (14) In the invention according to the fourteenth aspect, since there are portions where the number of color charts is smaller in the chart including the spot color than in the chart not including the spot color, the color measurement can be simplified.

(15) According to the invention, the ink jet printer can be realized by providing a special color head in addition to CMYK, and stable color reproduction can be performed.

(16) According to the sixteenth aspect of the present invention, in an ink jet printer, even if a pigment having durability but a narrow color gamut is used, color reproduction can be performed in a sufficient color gamut. .

(17) According to the seventeenth aspect of the invention, in the ink jet printer, it is possible to reduce roughness in the vicinity of gray which is most noticeable by adding a minimum amount of ink and a head.

(18) According to the eighteenth aspect of the present invention, in the ink jet printer, it is possible to stably reduce the roughness in the vicinity of gray which is most noticeable by adding a minimum amount of ink and a head. In addition, it is possible to use a minimum of special colors for a wide color gamut.

(19) According to the nineteenth aspect, it is possible to create a proof table without decomposing into a color for a color material, and it is possible to reduce the amount of calculation at that time.

(20) In the invention according to claim 30, in order to decompose a color gamut when a special color is used into a color gamut of a combination of four color gamuts, it is possible to use a conventional method for a four-color printer. it can. By giving the setting of K to each color gamut or the setting of the method of using the special color, the degree of freedom of the combination of the color materials can be increased.

[Brief description of the drawings]

FIG. 1 is a color separation image correction method according to an embodiment of the present invention;
FIG. 2 is a block diagram showing, for each functional block, an electrical configuration of a chart, an ink jet printer, a color separation image correcting device, and a device used for a recording medium.

FIG. 2 is an explanatory diagram showing an example of a chart according to the embodiment of the present invention.

FIG. 3 is an explanatory diagram showing an example of a chart according to the embodiment of the present invention.

FIG. 4 is an explanatory diagram showing an example of a chart according to the embodiment of the present invention.

FIG. 5 is an explanatory diagram showing an example of a chart according to the embodiment of the present invention.

FIG. 6 is an explanatory diagram showing an example of a chart according to the embodiment of the present invention.

FIG. 7 is an explanatory diagram showing an example of a chart according to the embodiment of the present invention.

FIG. 8 is an explanatory diagram showing an example of a combination of color materials in the embodiment of the present invention.

FIG. 9 is an explanatory diagram schematically showing a state of a color gamut volume in the embodiment of the present invention.

FIG. 10 is an explanatory diagram showing how errors increase due to smoothing in the embodiment of the present invention.

FIG. 11 is an explanatory diagram showing a state of an error change due to the number of smoothings in the embodiment of the present invention.

FIG. 12 is an explanatory diagram illustrating a connection function according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Address signal formation means 20 Color reproduction information storage means 25 Weight coefficient storage means 30 Processing means 40 Output means 50 Controller 60 Instruction means

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C262 AA24 AB17 BA12 BA14 BA19 BA20 BC01 BC19 EA10 EA11 5C074 AA02 AA10 BB16 DD24 DD28 EE20 FF15 5C077 LL01 LL19 MM27 MP08 PP02 PP33 PP37 PP38 PP39 PQ08 PQ23 SS05B 0505 LA21 LA24 LA31 LB01 MA04 NA03

Claims (30)

[Claims] 1. A color separation image for correcting a color separation image signal input as an electric signal to reproduce a target color using cyan C, magenta M, yellow Y, a high-saturation color material (special color) and Sumi K. A correction method comprising: combining K and a plurality of color gamuts generated by three chromatic colors to obtain a combination of actually used color materials; and selecting either a special color usage method or a K setting method. Or a step of providing both, and determining a combination of color materials used for image output. 2. The color separation image correcting method according to claim 1, wherein the generated color gamut includes a CMYK color gamut. 3. The generated color gamut includes at least one color gamut.
2. The color separation image correcting method according to claim 1, wherein a color gamut based on a combination of a color special color and two other colors is included. 4. The generated color gamut has at least two colors.
2. The color separation image correction method according to claim 1, wherein a color gamut based on a combination of a color special color and one other color is included. 5. The color separation image correcting method according to claim 1, further comprising a step of limiting a color material amount. 6. The color separation image correction method according to claim 2, wherein a method of using K near gray and a method of using a special color near high saturation can be designated as a color material setting method. . 7. The color separation image correcting method according to claim 6, further comprising a plurality of color conversion tables created according to claim 6, wherein the color conversion table is switched according to the remaining color material. 8. The color-separated image correction according to claim 6, comprising a plurality of color conversion tables created according to claim 6, wherein the color-separated image signal is switched according to the type of picture of the input color-separated image signal. Method. 9. The color separation image correcting method according to claim 1, wherein smoothing is performed on the color conversion table generated according to any one of claims 1 to 6. 10. The color separation image correcting method according to claim 9, wherein an error generated by said smoothing is corrected by another color conversion table. 11. A colorimetric chart, wherein:
A chart created by outputting a combination of colors created by the color separation image correcting method according to claim 5. 12. A colorimetric chart according to claim 1, wherein:
A chart which is an output of a combination of colors created by the color separation image correcting method according to any one of claims 5 to 9, wherein the chart is created without overlapping portions. 13. A colorimetric device for correcting a color separation image signal input as an electric signal to reproduce a target color by using cyan C, magenta M, yellow Y, a high-saturation color material (special color) and Sumi K. 3. The chart according to claim 1, wherein the chart is created without overlapping portions. 14. A colorimeter for correcting a color separation image signal input as an electric signal to reproduce a target color using cyan C, magenta M, yellow Y, a high chroma color material (special color) and Sumi K. 3. The chart according to claim 1, wherein the chart including the spot color has fewer color charts than the chart not including the spot color. 15. An ink jet printer adjusted by the color separation image correcting method according to any one of claims 1 to 10. 16. The ink-jet printer according to claim 1, wherein a color material based on a pigment is used.
5. The inkjet printer according to 5. 17. The ink jet printer according to claim 15, wherein at least two types of color materials are used for K. 18. The ink jet printer according to claim 17, wherein the printer is adjusted to use K as much as possible. 19. In parallel with the execution of the color separation image correction method, color coordinates after color gamut mapping are held, and a combination of color material amounts of other devices for reproducing the color coordinates is obtained. The color separation image correcting method according to claim 1, wherein: 20. A color separation image correcting apparatus for correcting a color separation image signal input as an electric signal and reproducing a target color by using cyan C, magenta M, yellow Y, a high chroma color material, and sumi K. A processing means for combining a plurality of color gamuts generated by K and three chromatic colors to obtain a combination of actually used color materials; and at least one of a method of using a special color or a method of setting K And an instructing means for receiving the instruction of (1), wherein a combination of coloring materials used for image output is obtained. 21. A color gamut generated by said processing means,
3. A color gamut of CMYK is included.
0. A color separation image correction device according to item 0. 22. The color gamut generated by the processing means includes:
21. The color separation image correcting apparatus according to claim 20, wherein a color gamut based on a combination of at least one spot color and two other colors is included. 23. A color gamut generated by the processing means,
21. The color separation image correcting apparatus according to claim 20, wherein a color gamut based on a combination of at least two spot colors and one other color is included. 24. The apparatus according to claim 20, wherein said processing means has means for limiting an amount of a color material.
3. The color separation image correcting device according to any one of 3. 25. The method according to claim 21, wherein the setting method of the color material specified by the specifying means can specify how to use K near gray and how to use a spot color near high saturation. The color separation image correction device according to the above. 26. The processing means comprises a plurality of color conversion tables created by the processing of claim 25.
26. The color separation image correcting device according to claim 25, wherein the switching is performed according to the remaining amount of the color material. 27. The apparatus according to claim 25, wherein said processing means comprises a plurality of color conversion tables created according to claim 25, and switches according to the type of picture of the input color separation image signal. Color separation image correction device. 28. The color processing method according to claim 20, wherein said processing means performs smoothing on the color conversion table generated by the processing according to any one of claims 20 to 25. Decomposition image correction device. 29. The color-separated image correcting apparatus according to claim 28, wherein said processing means corrects an error generated by smoothing by using another color conversion table. 30. A color separation image for correcting a color separation image signal input as an electric signal to reproduce a target color using cyan C, magenta M, yellow Y, a high-saturation color material (special color) and Sumi K. A computer-readable recording medium on which a correction processing program is recorded, wherein the color-separated image correction processing program combines K and a plurality of color gamuts generated by three colors of chromatic colors,
A computer-readable recording medium comprising: a step of obtaining a combination of color materials actually used; and a step of providing one or both of a special color use method and a K setting method.