JPH11146207A - Color image correction chart - Google Patents

Abstract

(57) [Summary] [Problem] To match a desired target color with high accuracy in response to color reproduction accuracy and state variation of an image output device for forming a color image, difference in appearance due to an observation environment, and the like. An object of the present invention is to provide a color image correction chart that can easily and quickly correct a color image. A reduced color patch group CMYd and an increased color patch group CMYi are arranged for a gray color reference chart Gray as a target color, and the reduced color patch group CMYd has device data to be made equal to the target color at the center. And a color patch in which only the main color is reduced stepwise at a predetermined pitch so as to be symmetrical with the target color patch CMY0d, and a color patch in which only the complementary color is reduced stepwise at a predetermined pitch. And the increased color patch group CMYi includes a color patch in which only the main color is increased and a color patch in which only the complementary color is increased.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a correction chart for a color image when an image output device forms a color image based on device data.

[0002]

2. Description of the Related Art In an image output apparatus for outputting a color image to an output medium such as a printed matter, a hard copy, and a CRT,
The color image is reproduced by implementing halftone area modulation and density modulation on the output medium based on C, M, Y, K, and R, G, B device data. In this case, the color characteristics of the reproduced color image largely depend on the properties of the color material and the support (output paper, phosphor, etc.) used.

Various methods have been proposed for obtaining device data capable of obtaining a desired color image, corresponding to various image output apparatuses and output media as described above. For example, a method for obtaining the device data by performing direct mapping conversion using a color conversion table obtained in advance under a specific printer or printing conditions, such as a technique described in JP-A-3-131920, JP-A-4-3628
No. 69, a method of obtaining a maximum likelihood solution of a coefficient of a masking process so that the colorimetric values of different image output devices match, and using the coefficient to obtain the device data There is.

However, even when a color image is reproduced using color conversion data that has been subjected to high-precision color matching processing, an image having a sufficiently satisfactory color may not be obtained.

That is, even if the image output device for outputting a color image has the same model, output method, output condition, and the like, there is a difference between the devices and a change with time, so that it is not possible to match the target color with the target color. Even when the color conversion data that can be set is set, an error may occur in the color of the reproduced color image. To correct such an error, it is not very realistic to perform the measurement and the calculation again using the method as described above in view of the labor and time.

On the other hand, when a proof of a color image is obtained, a color material and a support always have the same spectral characteristics in a target output medium such as a printed matter, a hard copy, and a CRT, and an output medium forming a proof. For example, if the spectral distribution of the observation light source is different, the reproduced color will be different from the target color.

Further, since the color conversion data set for the image output device is obtained using, for example, a color matching function based on an average human visual characteristic, the color appearance may vary depending on individual differences. May be different.

In order to correct the color conversion data of each image output device so that the color appearances match in consideration of the differences in the image output devices and viewing conditions as described above, for example, Japanese Patent Application Laid-Open In an image output apparatus capable of simulating the finish of a printed matter on a CRT as in the method described in Japanese Patent Application Laid-Open No. 60-114862, the output results of each output medium are compared with each other to match the appearance by trial and error. However, this method requires considerable labor and skill to adjust the output.

[0009]

SUMMARY OF THE INVENTION The present invention has been made in order to solve the above-mentioned disadvantages, and has been made in view of the following problems. An object of the present invention is to provide a color image correction chart that can easily and quickly correct a color image so as to match a desired target color with high accuracy in response to a difference or the like.

[0010]

According to another aspect of the present invention, there is provided a color chart for correcting a color image when a color image is formed by an image output apparatus based on device data. A target color patch created by the image output device based on device data to be matched to a color, and only the main colors constituting the device data for creating the target color patch in a stepwise manner at a predetermined pitch. A plurality of main color color patches created by the image output device based on the plurality of increased and decreased device data, and complementary colors to the main colors constituting the device data for creating the target color patch Based on a plurality of device data obtained by gradually increasing and decreasing only the image output device at a predetermined pitch. By and a plurality of complementary color patches created, the plurality of primary color color patches and the plurality of complementary color patch, characterized in that it is arranged symmetrically about said target color patches.

In this case, in the color image correction chart created by the image output device to be corrected, the main color patch and the complementary color patch are symmetrically arranged around the target color patch, and the hue is the main color. Since the color patches are arranged so as to change stepwise at a predetermined pitch from the target color to the complementary color, when the color patch corresponding to the target color is selected, the main color of the device data to be corrected and the correction amount thereof Can be recognized.

Further, by arranging each color patch in a straight line, the range of the color image correction chart in the output medium can be reduced. With this configuration, for example, it is possible to always output a color image correction chart on a printed material and to perform correction processing arbitrarily.

Further, the correction amount for the device data can be grasped more quickly by representing the color patches constituting the color image correction chart with numerical values indicating the deviation amount of the device data from the target color patch and the colors corresponding thereto. It becomes possible.

The main colors are C, M, Y or R, G,
B, and by arranging them and their complementary colors on a diagonal of a hexagon, the correction amount of the main color of the device data to be corrected can be more easily grasped.

Further, the color image correction chart is prepared by gradually increasing only the main color color patch and the complementary color, which are created from device data obtained by gradually increasing the main color at a predetermined pitch, at a predetermined pitch. An increased color patch group in which the complementary color patches created from the increased device data are arranged symmetrically, and the main colors created from the device data obtained by gradually decreasing only the main colors at a predetermined pitch. A color patch consisting of a color patch and a complementary color patch created from device data obtained by gradually reducing only complementary colors at a predetermined pitch, and a reduced color patch group arranged symmetrically. By arranging adjacent ones having similar hues and different lightness, respectively, the errors of the hue and the lightness are determined at the same time. The correction amount can be easily determined.

[0016]

FIG. 1 is a block diagram showing the configuration of an embodiment to which a color image correction chart according to the present invention is applied. In this embodiment, an image output apparatus is provided so that a proof that is visually identical in color to a printed material under a user's viewing condition can be created for a desired target color (gray in this embodiment). This is to correct ten characteristics. The conditions that affect the visual color matching include, for example, viewing conditions such as a light source for illuminating the printed matter, coloring materials forming the printed matter, and visual characteristics of a person who observes the printed matter.

When a printed matter is prepared, a color image recorded on a document is read by an input device 12 such as a scanner, and device data C, M, Y, and C are formed of halftone data of each of C, M, Y, and K colors. K (hereinafter, referred to as device data CMYK as necessary) and supplied to the printed matter producing apparatus 14. Based on the device data CMYK, for example, the printed matter creating device 14
A four-screen halftone film of K is created, a printing plate is created from the halftone film, and a printed matter is created using the printing plate.

On the other hand, when the proof of the printed matter is created, the device data CMYK from the input device 12 is supplied to the print proof creating device 16 in the image output device 10. In the print proof creating device 16, as shown in FIG. 2, in order to predict color reproduction characteristics in a colorimetric space,
The device data CMYK is based on color conversion data 18 (hereinafter referred to as a color reproduction prediction LUT (lookup table) 18) set in consideration of printing conditions, and colorimetric value data L ^* , a ^* , b ^* (hereinafter, referred to as color data). It is converted to colorimetric value data Lab as necessary.)

The color reproduction prediction LUT 18 creates a color chart by the printed matter creating device 14 for each printing condition based on the device data CMYK, and measures the colorimetric value data L ^* , It can be obtained from a ^* and b ^* .

Next, the colorimetric value data Lab is converted into device data R, G, B (hereinafter, referred to as “device data”) by a data conversion LUT 22 set in consideration of the characteristics of the proof output device 20.
It is referred to as device data RGB as needed. ) And supplied to the proof output device 20. The proof output device 20 drives a laser beam or the like based on the device data RGB to output a proof corresponding to the printed matter.

Next, a method for correcting the printed matter and the proof so that the printed matter and the proof become equal in gray color using the color image correction chart CH shown in FIG. 3 under an arbitrary observation condition of the user will be described. This will be described according to the flowchart shown in FIG.

First, the color reproduction prediction LUT 1 is output by the color reproduction prediction LUT correction unit 24 in the print proof creation device 16.
8 is read (step S2). Here, the color reproduction prediction LUT 18 is assumed to be a function F below, and the relationship between the device data CMYK and the colorimetric value data Lab is represented by Lab = F (CMYK) (1).

Next, the relationship between the colorimetric value data Lab and the device data CMY when the device data K is set to 0 is calculated by using the inverse function F ^{-1 of the} equation (1) as follows: CMY = F ^-1 (Lab) (2) (step S4). Note that this inverse function F ^-1
Can be obtained from Expression (1) by, for example, inverse transformation using Newton's successive approximation method or the like. The inverse function F ^-1
Is set in the print proof creating device 16 as the data conversion LUT 26.

Next, a gray color reference chart, which is a reference reference chart of a target color having a predetermined gradation, is created (step S6). In this case, the K-plate printed matter created based on the device data K is almost completely achromatic as a color, and it is considered that the color hardly changes depending on the user's viewing conditions. , A gray reference chart can be created by the printed matter creating apparatus 14. The gray reference chart can be created by any other method.

On the other hand, device data CMY which is metametrically equal to the gray color of the gray color reference chart as the target color is calculated using the data conversion LUT 26 (step S8). This is set as CMY balance data CMY (gray). That is, when the gray reference chart is created by the printed matter creating apparatus 14 using the device data K,
The MY balance data CMY (gray) is represented by C = M = Y
= 0, the colorimetric value data Lab for the device data K is obtained from the equation (1), and the colorimetric value data Lab is obtained as CMY (gray) = F ⁻¹ (Lab) (3) it can. When the CMY balance data CMY (gray) is created by any other method that does not use the device data K, the colorimetric data Lab is measured, and the CMY balance data CMY (gray) is calculated by using the above equation (3). Can be determined using In this case, the CMY balance data CMY (gray)
Is the equivalent neutral concentration (END:
Equivarent Neutral Density) or Equivalent Neutral Ink Value (ENIV).

Next, the CMY balance data CMY (gr
a)), a plurality of neighborhood data obtained by slightly changing the device data CMY constituting the CMY balance data is obtained, and a CMY balance chart is output from the CMY balance data CMY (gray) and the plurality of neighborhood data by using the printed matter creating apparatus 14 ( Step S10).

FIG. 3 shows a gray reference chart Gray, which is the target color created as described above, and C
A reduced color patch group CMY which is a MY balance chart
6 shows a color image correction chart CH composed of a color patch group d and an increased color patch group CMYi. The color image correction chart CH includes a gray reference chart Gray, a reduced color patch group CMYd in which a plurality of color patches are arranged in a hexagonal shape, and an increased color patch group CMYi formed on the same recording medium. However, the gray reference chart Gray may be formed on another recording medium.

Here, color patches CMY0d and CMY0i (for example, C = 6) arranged at the center of the reduced color patch group CMYd and the increased color patch group CMYi.
0%, M = 50%, Y = 50%, CMY0d = CMY
0i) is a target color patch created from the CMY balance data CMY (gray).

In the reduced color patch group CMYd, the color patch CMY is placed above the color patch CMY0d.
A main color patch C-10 (for example, C = 50) in which only the main color device data C is reduced by 10% from 0d.
%, M = 50%, Y = 50%) and the color patch CMY
A main color patch C-20 (for example, C = 40) in which only the main color device data C is reduced by 20% from 0d.
%, M = 50%, Y = 50%). Below the color patch CMY0d, a complementary color patch R-10 in which the complementary color of the device data C is reduced by 10% from the color patch CMY0d (for example, C = 60%, M = 40%,
Y = 40%) and a complementary color patch R in which the complementary color of the device data C is reduced by 20% from the color patch CMY0d.
-20 (for example, C = 60%, M = 30%, Y = 30
%) Are arranged.

At the lower right corner of the color patch CMY0d, a main color patch M-1 in which only the main color device data M is reduced by 10% from the color patch CMY0d.
0 (for example, C = 60%, M = 40%, Y = 50%)
And a main color patch M-2 in which only the main color device data M is reduced by 20% from the color patch CMY0d.
0 (for example, C = 60%, M = 30%, Y = 50%) are arranged. Above the left side of the color patch CMY0d, a complementary color patch G-10 (for example, C = 50%, M = 50%, Y = 40%) in which the complementary color of the device data M is reduced by 10% from the color patch CMY0d. 20% of complementary color of device data M from color patch CMY0d
The reduced complementary color patch G-20 (for example, C = 4
0%, M = 50%, Y = 30%).

At the lower left of the color patch CMY0d, a main color color patch Y-1 in which only the main color device data Y is reduced by 10% from the color patch CMY0d.
0 (for example, C = 60%, M = 50%, Y = 40%)
And a main color patch Y-2 in which only the main color device data Y is reduced by 20% from the color patch CMY0d.
0 (for example, C = 60%, M = 50%, Y = 30%) are arranged. Above and to the right of the color patch CMY0d, a complementary color patch B-10 (for example, C = 50%, M = 40%, Y = 50%) in which the complementary color of the device data Y is reduced by 10% from the color patch CMY0d. 20% of complementary color of device data Y from color patch CMY0d
The reduced complementary color patch B-20 (for example, C = 4
0%, M = 30%, Y = 50%).

Further, between the main color patch C-20 and the complementary color patch B-20, the complementary color patch B-
20, between the main color patch M-20 and the complementary color patch R-20,
Complementary color patch R-20 and primary color patch Y-2
0, between the main color patch Y-20 and the complementary color patch G-20, and between the complementary color patch G-20 and the main color patch C-20, the intermediate color patch Md1 ( For example, C = 40%, M = 40%, Y =
50%), Md2 (for example, C = 50%, M = 30%,
Y = 50%), Md3 (for example, C = 60%, M = 30)
%, Y = 40%), Md4 (for example, C = 60%, M =
40%, Y = 30%), Md5 (for example, C = 50%,
M = 50%, Y = 30%), Md6 (for example, C = 40
%, M = 50%, Y = 40%).

The increased color patch group CMYi stores the device data of the main color and the complementary color by one more than the target color patch.
Color patches C + 10, B + 10, M + increased by 0%
10, R + 10, Y + 10, G + 10 and color patches C + 20, B + 20, M + 20, R + increased by 20%
20, Y + 20, G + 20 and their intermediate color patches Mi1 to Mi6 are arranged in the same manner as the reduced color patch group CMYd.

Therefore, the operator inputs the gray reference chart Gray created as described above, the reduced color patch group CMYd and the increased color patch group CM.
Yi is observed under the observation conditions under which the proof is to be confirmed, and a color patch that is visually the same color is selected in the gray reference chart Gray (step S1).
2).

In this case, if the printed matter and the proof are observed under exactly the same observation conditions as when the color reproduction prediction LUT 18 is defined, the gray color reference chart G
It is the center color patch CMY0d or CMY0i that visually matches the color of the ray (see FIG. 5A). However, when the observation conditions are different, the color patches C that visually match in color are different because the spectral characteristics of the illumination light source are different or the visual characteristics of the observer are different.
MY 'is usually a color patch CMY' at a position shifted from the center color patch CMY0d or CMY0i (see FIG. 5B). Therefore, the central color patch CMY
A deviation amount CMY (differ) of data between 0d or CMY0i and a color patch CMY ′ that matches the gray color reference chart Gray is obtained, and the CM
The Y balance data CMY (gray) is corrected.

Here, as shown in FIG. 3, the color image correction chart CH of the present embodiment is symmetrically arranged so that the main color and the complementary color increase or decrease in a stepwise manner. It is possible to instantly grasp which main color or which complementary color should be increased or decreased. Further, by using the reduced color patch group CMYd and the increased color patch group CMYi, it is possible to detect not only a hue but also a difference in lightness. For example, the color patch C-20 and the color patch R + 20 are very close in hue, but have significantly different lightness. In this case, by determining whether the CMY balance data CMY (gray) is closer to the decreasing color patch group CMYd or the increasing color patch group CMYi, it is determined whether the number of main colors is large or small, or
It is easy to determine whether there are many or few complementary colors.

Therefore, based on the result of the judgment as described above, CMY balance data CMY '(gray) which can make the printed matter and the proof color equal to the target color gray under different observation conditions is obtained. , G using the function G (step S14).

CMY ′ (gray) = G (CMY (gray), CMY (differ)) (4) Hereinafter, the CMY balance data CMY ′ (gray)
The method for obtaining the following will be described. In this case, the corrected C
The device data Cadj, Madj, and Yadj constituting the MY balance data CMY ′ (gray) are represented by a linear combination polynomial of the device data C, M, and Y constituting the CMY balance data CMY (gray) before correction, and Cadj = a0 + a1 · ^{C + a2 · C 2 + ...} + an · C n Madj = a0 + a1 · M + a2 · M 2 + ... + an · M n Yadj = a0 + a1 · Y + a2 · Y 2 + ... + an · Y n ... can be expressed as (5). Here, a0 to an are coefficients, and n is a natural number.

Therefore, the k point (k) of the CMY balance data CMY (gray) before correction for the device data C
Assuming that the device data of ≧ n + 1) is C1 to Ck, the corrected device data Cadj1 to Cadjk newly obtained from the above-mentioned shift amount CMY (differ).
Becomes a (5), Cadj1 = a0 + a1 · C1 + a2 · C1 2 + ... + an · C1 n ... Cadjk = a0 + a1 · Ck + a2 · Ck 2 + ... + an · Ck n ... (6). When the equation (6) is expressed by a determinant, it can be described as Y = X · A (7). In addition,

[0040]

(Equation 1)

Is as follows. Here, instead of once setting equation (6), the matrix of equation (8) may be directly set, or a look-up table may be set to find coefficient A.

The coefficient A that satisfies the relation of the equation (7) is obtained by using the least square method so that the error e shown in the following equation (9) is minimized. In equation (9), T represents transposition in which rows and columns of the matrix are interchanged.

E = (Y−X · A) ^T · (Y−X · A) (9) The condition for minimizing the error e is as follows: ∂e / ∂A = −2 × ^T · (Y−X A) = 0 (10) Therefore, the coefficient A can be obtained from the equation (10), and the corrected device data Cadj can be obtained by substituting the coefficient A into the equation (5).

Similarly, the corrected device data Ma
dj and Yadj can be obtained. From these data, the corrected CMY balance data C shown in FIG.
MY '(gray) is obtained.

The CMY balance data CMY '
(Gray) is a shift amount CMY (dif of one point between 0 and 100% obtained from the color image correction chart CH.
fer) and fixed 0% and 100% CMY balance data CMY (gray).

By the way, the C obtained as described above
When the correction of the color reproduction prediction LUT 18 for all colors is performed using the MY balance data CMY '(gray), the effect of the correction also occurs for colors other than the target color. Is performed so that the correction is performed on.

That is, the correction amount for the gray color is applied to the normal probability distribution process, and the weighting function H (μ, σ,
t),

[0048]

(Equation 2)

Is set. In equation (11), the probability density function φt is φt = 1 / (√ (2π) · σ) · exp (− (x−μ) ² / 2σ ² ) (12) where t is The degree and σ represent the standard deviation of the saturation, and μ represents the average value of the saturation. Therefore, the user sets μ = 0 since the saturation of the gray color is 0 in the equation (11), and sets the degree of correction weighting as the standard deviation value σ (step S16, see FIG. 6). ). Then, using the set average value μ and standard deviation value σ, a weighting function H (μ, σ, t) for the CMY balance data CMY ′ (gray) is obtained (step S18). Here, the saturation t is the device data CMY shown in the equation (1).
Color reproduction prediction LUT1 for converting K into colorimetric value data Lab
T = CH (F (CMYK))... (13) The function CH is as follows: CH = √ (a ^{* 2} + b ^{* 2} ) (14)

Using the weighting function H (μ, σ, t) obtained as described above, the CMY balance data CM
By performing weighting on Y ′ (gray),
New CMY balance data CMY "(gray) is obtained as CMY" (gray) = CMY '(gray) .H (μ, σ, t) (15). Then, the CMY balance data CM
From the Y ″ (gray) and the device data K, a corrected color reproduction prediction LUT 18 (function F ′) capable of obtaining colorimetric value data Labadj as Labadj = F ′ (CMYK) (16) is created. (Step S20).

The color reproduction prediction L created as described above
The UT 18 is set in the print proof creation device 16, and a proof is created using the color reproduction prediction LUT 18. In this case, since the proof is a gray color which is a desired target color corrected in accordance with the viewing conditions, a proof in which the visual color matching relationship with the gray color is compensated is obtained. In addition, when correcting the color reproduction prediction LUT 18, the gray color is weighted for correction using the probability density function φt composed of a Gaussian curve, and the weight for the surrounding colors is reduced. The correction can be performed only for the correction, and unnatural color reproduction due to the correction does not occur.

In the above-described embodiment, the target color to be corrected may be a color other than the gray color. For example, under the same measurement conditions as when the color reproduction prediction LUT 18 before correction was created, a reference chart serving as a reference for skin color and the like was created as a printed matter, and colorimetric value data Lab obtained by measuring the color of the reference chart was used. Using the color reproduction prediction LUT 18 before correction, CMY balance data to be made equal in color to the reference chart is calculated, and the CMY balance chart is output by the printed matter creating device 14 based on the CMY balance data and a plurality of data in the vicinity thereof. I do. Then, by comparing the reference chart and the CMY balance chart, a shift amount CMY (differ) is obtained, and (4)
Color reproduction prediction LU corrected according to equation (15) and equation (15)
What is necessary is just to ask for T18. Note that the average value μ of the saturation in the weighting function H (μ, σ, t) in Expression (15) may be set in accordance with the saturation of the target color as shown by a dotted line in FIG. .

Incidentally, the present invention is not limited to the case where the printed matter and its proof are made to be the same color as the target color.
As shown in FIGS. 7 and 8, a plurality of image output devices 30 including a printer 28 and a display 32 such as a CRT are provided.
The present invention can also be applied to a case in which color matching is realized in consideration of a machine difference between a plurality of image output devices 34 having the above, a difference in observation conditions, and the like.

For example, in the case of the image output device 30 shown in FIG.
A calibration chart and a reference plate are prepared for use, the device data having the same color as the reference reference chart and the metameric color are obtained using the color conversion data, and the output balance chart and the reference reference chart are compared. Thus, the color conversion data can be corrected. In this case, the deviation of the target color due to the machine difference among the plurality of printers 28 can be corrected very easily. Similarly, it is possible to correct the deviation of the target color in the color image displayed on the display 32.

The color image correction chart CH is
It can also be used as a means for adjusting printing conditions such as the amount of ink and printing pressure so that the printed matter matches the color of the desired reference reference chart. In this case, as described above, the color image correction chart CH can be used as an extremely simple correction means because it is possible to instantaneously determine which of the main color and its complementary color should be increased or decreased. .

It should be noted that the color image correction chart CH shown in FIG. 3 can be combined to form a configuration as shown in FIG. That is, the color image correction chart C shown in FIG.
H1 is composed of one color patch group CMYm in which the reduced color patch group CMYd and the increased color patch group CMYi shown in FIG.
In this case, the operator sets the gray reference chart G
It is possible to instantly determine which of the primary color and the complementary color should be increased or decreased in both the hue and the lightness of the target color patch with respect to the target color patch, and a color image correction chart. CH1
This also has the effect of reducing the area of the recording medium occupied by.

As shown in FIG. 10, each color patch constituting the color image correction chart CH shown in FIG. 3 is set so that the main color patch and the complementary color patch are symmetric about the target color patch. May be used as the color image correction chart CH2 arranged in a state in which is held. Further, as shown in FIG. 11, the color image correction chart CH1 shown in FIG. 9 may be a color image correction chart CH3 arranged in the same manner as in FIG.

Further, as shown in FIG. 12, the color patches on the diagonal line of the hexagon of the color image correction chart CH shown in FIG.
The color image correction chart CH4 may be linearly arranged by displaying a numerical value representing (Differ). In this case, the shift amount CMY (Differ)
Can be obtained directly, so that a quick and accurate correction operation can be performed.

In the case where the color patches are arranged linearly as in the above-described color image correction charts CH2, CH3 and CH4, the occupied area can be reduced. For example, as shown in FIG. And a color image correction chart C on the end of the color image output sheet S.
H5 is always output, and device data can be corrected at an arbitrary date and time.

[0060]

As described above, by using the color image correction chart according to the present invention, it is possible to cope with the color reproduction accuracy of an image output apparatus for forming a color image, fluctuations in state, differences in appearance due to an observation environment, and the like. In addition, it is possible to quickly and accurately obtain the correction amount of the device data based on the difference in the hue and the brightness, and easily form a color image that matches the desired target color with high accuracy.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of an embodiment in which a proof for a printed matter is visually made equal in color according to observation conditions.

FIG. 2 is a block diagram showing a configuration of a print proof creating apparatus shown in FIG.

FIG. 3 is a configuration diagram of a color image correction chart according to the present invention.

FIG. 4 is a flowchart of a gray color conversion accuracy correction method in the configuration shown in FIG. 1;

5A is an explanatory diagram of CMY balance data before correction, and FIG. 5B is an explanatory diagram of CMY balance data after correction.

FIG. 6 is an explanatory diagram of a weighting function for CMY balance data.

FIG. 7 is a configuration block diagram of another embodiment.

FIG. 8 is a configuration block diagram of still another embodiment.

FIG. 9 is a configuration diagram of another embodiment of a color image correction chart according to the present invention.

FIG. 10 is a configuration diagram of another embodiment of a color image correction chart according to the present invention.

FIG. 11 is a configuration diagram of another embodiment of a color image correction chart according to the present invention.

FIG. 12 is a configuration diagram of another embodiment of a color image correction chart according to the present invention.

FIG. 13 is an explanatory diagram in which a color image correction chart according to the present invention is formed on a recording medium.

[Explanation of symbols]

10, 30, 34 ... Image output device 12 ... Input device 14 ... Printed matter creation device 16 ... Print proof creation device 18 ... Color reproduction prediction LUT 20 ... Proof output device 22, 26 ... Data conversion LUT 24 ... Color reproduction prediction LUT correction unit 28 ... Printer 32 ... Display CH, CH1-CH5 ... Color image correction chart CMYd ... Decrease color patch group CMYi ... Increase color patch group CMYm ... Color patch group

Claims (7)

[Claims] 1. A correction chart for a color image when a color image is formed by an image output device based on device data, the chart being created by the image output device based on device data to be made equal to a target color. The target color patch, and the image output based on a plurality of device data obtained by gradually increasing and decreasing only the main colors constituting the device data for creating the target color patch at a predetermined pitch. A plurality of main color color patches created by the apparatus, and a plurality of main colors formed by gradually increasing and decreasing only complementary colors to the main colors constituting the device data for creating the target color patch at a predetermined pitch. Based on device data, a plurality of complementary color patches created by the image output device, A color image correction chart, wherein the plurality of main color patches and the plurality of complementary color patches are arranged symmetrically with respect to the target color patch. 2. The color image correction chart according to claim 1, wherein the target color patch, the main color patch, and the complementary color patch are arranged linearly. 3. The chart according to claim 1, wherein the main color patch and the complementary color patch each include a numerical value indicating an amount of deviation of device data from the target color patch. A color image correction chart formed by coloring with a color created by the image output device based on device data of a patch. 4. The chart according to claim 1, wherein the main colors are composed of C, M, and Y device data.
A color image correction chart, wherein the main color patch and the complementary color patch are arranged on a hexagonal diagonal centered on the target color patch. 5. The chart according to claim 1, wherein the main colors are R, G, and B device data,
A color image correction chart, wherein the main color patch and the complementary color patch are arranged on a hexagonal diagonal centered on the target color patch. 6. The chart according to claim 1, wherein the chart includes only the main color patch and the complementary color created from device data obtained by increasing only the main color stepwise at a predetermined pitch. A group of increased color patches in which the complementary color patches created from device data gradually increased at a pitch are arranged symmetrically, and a device obtained by gradually decreasing only the main color at a predetermined pitch. A reduced color patch group in which the main color color patch created from data and the complementary color patch created from device data obtained by gradually reducing only the complementary color at a predetermined pitch are arranged symmetrically. A color image correction chart characterized by being performed. 7. The chart according to claim 6, wherein the color patches forming the increasing color patch group and the decreasing color patch group are arranged such that the color patches having similar hues and different lightness are adjacent to each other. A color image correction chart characterized by being performed.