JP2002152528A - Color correction driver and method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To properly correct tricolor signals in such a manner that a specific color, for instance grey, is properly corrected. SOLUTION: There are provided a color conversion unit 8 which converts image data (R0, G0 and B0) expressed by variables R, G and B into CMY data (C0, M0 and Y0) expressed by variables C, M and Y; and a color correction unit 11 which corrects the CMY data (C0, M0 and Y0) into corrected CMY data (C1, M1 and Y1). A plurality of test prints are made according to a plurality of corrected CMY data (C0+ΔCj, M0+ΔMj and Y0+ΔYj) obtained by changing the mixing ratios of the CMY data (C0, M0 and Y0) of a specific DUTY. The CMY data (C0, M0 and Y0) are corrected into one set of corrected CMY data (C0+ΔCk, M0+ΔMk and Y0+ΔYk) corresponding to one test print as the corrected CMY data (C1, M1, and Y1). Wherein, (j) denots an integer from 1 to (n), and (k) denotes one of the integers. According to the test results obtained by making the plurality of test prints with darkness corrected step by step, user can properly correct a specific color.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a color correction driver,
More particularly, the present invention relates to a color correction driver that corrects CMY data to perform color correction, and a color correction method.

[0002]

2. Description of the Related Art A color printer is a printing machine for printing an image on a prescribed sheet based on a prescribed mixing ratio of three primary color inks. A printer driver for controlling a mixture ratio is used to express a specified color on a prescribed sheet. In a color printer, paper is usually most standardly specified. Printing is performed with an appropriate color and density according to the specified paper. In practice, the prescribed paper is often not used, and even when the prescribed paper is used, the printing of the appropriate color and density is not performed by the ambient light. When the specified paper is not used, it is appropriate as intended for people who can visually recognize subtle colors due to differences in the colors of the paper itself, differences in ink absorption characteristics, and differences in ambient light. It is difficult to perform printing with an appropriate color and density. If the paper is colored rather than white, the color of the paper becomes the reference for white, so it may be preferable that the process black print result is also colored. A technique for selecting an appropriate density characteristic based on test printing is disclosed in
No. 00-62300.

[0003] It is required to correct three-color signals for a specific color. In particular, optimization of gray is required. Furthermore, an appropriate correction may be required for an arbitrary specific color.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a color correction driver and a color correction method for appropriately correcting three-color signals. It is another object of the present invention to provide a color correction driver and a color correction method in which correction of gray is optimized. Still another object of the present invention is to provide a color correction driver and a color correction method capable of appropriately correcting any specific color.

[0005]

Means for solving the problem are described as follows. The technical items appearing in the expression are appended with numbers, symbols, and the like in parentheses (). The numbers, symbols, and the like are technical items that constitute at least one embodiment or a plurality of the embodiments of the present invention, in particular, the embodiments or the examples. Corresponds to the reference numerals, reference symbols, and the like assigned to the technical matters expressed in the drawings corresponding to the above. Such reference numbers and reference symbols clarify the correspondence and bridging between the technical matters described in the claims and the technical matters of the embodiments or examples. Such correspondence / bridge does not mean that the technical matters described in the claims are interpreted as being limited to the technical matters of the embodiments or the examples.

[0006] The color correction driver according to the present invention includes a variable R,
Image data (R0, G0, B0) represented by G and B is converted to CMY data (C0, M) represented by variables C, M and Y.
(0, Y0) and a CMY data (C0, M0, Y0).
1, Y1). CMY data of the specified DUTY (C0,
A plurality of test prints are printed based on a plurality of corrected CMY data (C0 + ΔCj, M0 + ΔMj, Y0 + ΔYj) in which the mixture ratio of (M0, Y0) is changed. One corrected CMY data (C0 + Δ) corresponding to one test print
In Ck, M0 + ΔMk, Y0 + ΔYk, CMY data (C0, M0, Y0) is corrected CMY data (C1, M
1, Y1). j is an integer from 1 to n, and k is one of the integers.

The CMY data of the specified DUTY (C
The mixing ratio of (0, M0, Y0) is selected visually by the user or automatically by the optical device based on the result of the test printing. One group of corrected CMY data (C0 + ΔCj, M0 + ΔMj, Y0 + ΔYj) is 1
The reference colors (C0, M0, Y
0) little by little. Since the correction range is limited, the deviation is small. One selected (C0
+ ΔCj, M0 + ΔMj, Y0 + ΔYj), the subsequent printing is performed for the reference color that is the color to be corrected. Since the color to be corrected is specified, more appropriate color correction can be performed. The specified color to be corrected is not limited to a single color, and is not necessarily a specific color. In general, correction for gray is often performed. However, depending on the nature of a printed matter (a photograph of a red rose), the correction target is not limited to gray but red. Preferably, the correction function can be set by the user.

When the color to be corrected is gray, ΔYj
May be zero. For DUTY, gray 25% and gray 50% are often selected. Such%
Optionally, for example, based on 25% gray and 50% gray, test printing is performed in one or two ways at DUTY before and after that%. Looking at the results of such printing, the printing of the% that the user deems most appropriate is then performed. % Of DUs that users find most appropriate
TY is stored in the correction parameter storage unit (23).

The correction is functionalized. CU = C0 + ΔC
k, MU = M0 + ΔMk, CU, MU and Y
0 is represented by the following formula: CU '= CU * (C0 + M0 + Y0) / (CU + MU + Y0) MU' = MU * (C0 + M0 + Y0) / (CU + MU + Y0) YU '= Y0 * (C0 + M0 + Y0) / (CU + MU + Y0)' U ', Y0. In this case, Y0 has not been corrected.

Regarding C0, one corrected CMY data corresponding to one test print selected from a plurality of test prints printed based on a plurality of corrections in which the value of the specific DUTY is changed includes CMY data (C0, M0, Y0) can be corrected as corrected CMY data (C1, M1, Y1). CU 'is selected by the user as C0,
U ', MU, and Y0 are represented by the following formulas: CU' = CU 'MU' = {MU * (C0 + M0 + Y0) / (CU + MU)
+ Y0)｝ * CU '/ CU YU' = ｛Y0 * (C0 + M0 + Y0) / (CU + MU
+ Y0)｝ * CU '/ CU Further corrected to CU', MU ', YU'.
Such correction is not limited to C0, but is also possible for M0 and Y0, and correction for an arbitrary color is possible on the user side.

[0011] The color correction method according to the present invention uses the variables R, G,
Image data (R0, G0, B0) represented by B is converted to CMY data (C0, M0, Y) represented by variables C, M, and Y.
0), CMY data (C
0, M0, Y0), the three variables C0,
Changing the value of one or more selection variables selected from M0 and Y0 in a plurality of steps, and changing the values of the plurality of correction variables on the test print sheet based on the plurality of correction selection variables changed by the change. The method includes executing a test print in a stage, and selecting one correction selection variable from a plurality of correction selection variables from a print result obtained by the test print.

The specified CMY data (C0, M0, Y
It is preferable that the number of DUTY specified in 0) is plural. One of the DUTYs is 25% and the 25% multiple correction selection variable is 54 / 255-72 / 255. In the data, the concentration is defined in a scale of 0 to 255. DUTY
The other is 50%. Preferably, the 50% multiple correction selection variable is 120 / 255-136 / 255. Correction of color in this range is sufficient. In this case, the specified CMY data is preferably gray.

[0013]

FIG. 1 is a block diagram showing an embodiment of a color correction driver according to the present invention.
And an ink jet printer. The CPU 1 controls a printer driver 3 that drives an inkjet printer 2, as shown in FIG.
The CPU 1 sends a print command (signal) 4 to the printer driver 3.
To send to. The inkjet printer 2 sends the print data (signal) 5 to the inkjet printer 2.

The printer driver 3 includes an image data receiving unit 7 for receiving the RGB data 6 and a color conversion processing unit 8. The image data receiving unit 7 receives the RGB data 6 based on the print command 4. RGB data 6 is RGB
(R0, G0, B0). Image data receiving unit 7
Transmits the received RGB data 6 to the color conversion processing unit 8. The color conversion processing unit 8 converts the RGB (R0, G0, B0)
Is converted into CMY data 9 (R0, G0,
B0 → C0, M0, Y0). The color conversion processing unit 8
The CMY data 9 after the color conversion processing is output. The CMY data 9 is represented by CMY (C0, M0, Y0).

The printer driver 3 includes a density correction processing unit 1
1 is further provided. CMY (C0, M0, Y0) 9
Is input to the density correction processing unit 11. The density correction processing unit 11 corrects the density of CMY (C0, M0, Y0) 9 to obtain density-corrected data CMY (C1, M1, Y1) 1
2 is output. The density correction processing unit 11 includes a binarization processing unit 1
3 is connected. CMY (C1, M1, Y1) 12
Is input to the binarization processing unit 13. Binarization processing unit 13
Is the density corrected data CMY (C1, M1, Y1) 1
2 is binarized and binarized (C1, M1, Y1 → C
2, M2, Y2, K2). Binarization processing unit 13
Are binarized data CMYK (C2, M2, Y
2, K2) 14 is output. Binarized data CM
The YK (C2, M2, Y2, K2) 14 is sent to the inkjet printer 2 as print data 5 via the image data transmission unit 10.

FIG. 2 shows the details of the density correction processing section 11. The density correction processing section 11 includes a screen input control section 15. An operation instruction 1 is transmitted to the screen input control unit 15 via an operation device 16 including a mouse and a keyboard.
7 is input. The operation instruction 17 and operation information related to the operation are output from the screen input control unit 15 and displayed on the image display 18. The screen input control unit 15
An operation instruction 19 corresponding to an operation instruction 17 input by the operation device 16 is output.

The density correction processing section 11 further includes a test print output section 21, a density correction control processing section 22, and a correction parameter storage section 23. The operation command 19 is input to the test print output unit 21 and the density correction control processing unit 22. The correction parameters 24 are bidirectionally exchanged between the density correction control processing unit 22 and the correction parameter storage unit 23, and are stored in the correction parameter storage unit 23. Test print output unit 2
1 outputs the gray correction test pattern data 25 based on the received operation command 19.

The density correction control processing section 22 outputs density correction processing control data 26. The gray correction test pattern data 25 is input to the image conversion control unit 27 together with the density correction processing control data 26. The CMY data 9 output from the color conversion processing unit 8 is input to the image conversion control unit 27. Based on the gray correction test pattern data 25, the density correction processing control data 26, and the CMY data 9, the image conversion control unit 27 outputs the CMY (C1, M1, Y1) 12
Is generated and output.

The RGB data (R0, G0, B0) 6 is
It is expressed in a data format of an integer value of 0 to 255. C
The MY data (C0, M0, Y0) 9 is expressed in a data format of integer values from 0 to 255. Density correction processing unit 1
In 1, the test print output unit 21 executes a density correction test based on the density correction, and the parameters of the correction test are selectively stored in the correction parameter storage unit 23. The CMY data (C0, M0, Y0) 9 is stored in the density correction control processing unit 2
At 2, the density is corrected to CMY (C1, M1, Y1) 12. CMY (C1, M1, Y1) 12 is expressed in a data format of 0 to 255.

FIG. 3 shows an embodiment of a color correction method according to the present invention. The printer driver 3 is provided with a gray correction button (not shown). The gray correction button is pressed, and the execution of step S30 is started. The dialog box is an image display 18
Is displayed (step S31), and whether or not to print the gray correction test pattern shown in FIG. 4 is selected (step S32). Depending on the choice of performing a test print,
Printing of the gray correction test pattern shown in FIG. 4 is executed (step S33). This test printing is executed on a test sheet on which the inkjet printer 2 is mounted, based on the print data 5 sent from the image data transmission unit 10. This test printing is executed based on a test pattern sent from the test print output unit 21.

FIG. 4 shows a test print pattern sent from the test print output unit 21. The test print is based on the reference gray and the reference gray from C,
The mixture is executed in a different pattern with the mixture ratio of M and Y being slightly shifted. FIG. 4 shows a plurality of pattern groups 31 whose mixing ratios of C and M are slightly different from each other, with a print pattern having a DUTY of 25% as the center (Y is 64/256 and constant at 25%). Centering on the print pattern (Y is 128/256 and constant at 50%), C,
A plurality of pattern groups 32 with slightly different mixing ratios of M are shown.

The pattern shown in FIG. 5 corresponds to (2) in FIG.
2 shows an enlargement of an image of printing indicated by K, and is a pattern printed in pure black and 25% DUTY.
It is an illustration of printing of K by 5% DUTY. Such prints are printed in a color that is deemed suitable for 25% DUTY black. Printed matter on which printing equivalent to such printing has been performed may be attached to the product in advance, and the attached printed matter may be referred to. From the results of the printing of the patterns shown in FIGS. 4 and 5, a mixture ratio of CMY suitable for the printing paper is determined (step S).
34).

The selective determination of the density correction processing for the printing paper on which the test printing has been performed will be described next. Considering process black printing, process gray printing results that are originally not colored appear tinted due to differences in color between papers, differences in ink absorption characteristics, and differences in environment for each type of paper used. Would. If the paper has a color, the color of the paper is used as a reference for white, so that it may be preferable that the process black print result is also colored.

Based on such circumstances, the user visually judges and selects a preferable gray. At this time, 25% D of pure black which is not easily affected by paper etc.
It is easier to make a determination by referring to the UTY pattern (step S34).

FIG. 6 shows a method of density correction. According to the mixture ratio of CMY selected by the user based on the print test results of FIGS. 4 and 5, gray can be printed.
The density characteristics of C and M are respectively corrected. FIG. 6 shows output data (C1, M0) with respect to input data (C0, M0).
M1). With such functions CU = CU (C0) and MU = MU (M0), DUTY (C0, M0) as input data is changed to (CU, MU) selected by the user. Such a correction curve shown in FIG. 6 is partially linear,
It can be properly represented in part by non-linearity. If Y is not corrected, the correction equation is expressed by the following equation according to the functional relationship in the figure. CU = CU (C0), MU = MU (M0), YU = Y0

An example of a correction equation in the case where the correction is also performed for Y is shown by the following equation. CU '= CU ・ (C0 + M0 + Y0) / (CU + MU + Y0) MU' = MU ・ (C0 + M0 + Y0) / (CU + MU + Y0) CU '= Y0 ・ (C0 + M0 + Y0) / (CU + MU + Y0)

CU and MU are reference colors (C0 + M0 + Y
0) or (C0 + M0) is changed stepwise little by little. The plurality of corrected CMY data are (C0
+ ΔCj, M0 + ΔMj, Y0 + ΔYj). From the test results, one of them (C0 + ΔCk,
M0 + ΔMk, Y0 + ΔYk) are selected. ΔCk,
ΔMk and ΔYk can be arbitrarily selected, and it is preferable that these correction values are defined on the user side.

Alternatively, for one color of (C0 + M0 + Y0), for example, printing of 25% DUTY and printing of DUTY close to it are performed for C0 to obtain DUTY25.
Let the user choose what is preferred as the%
U '. In this case, the following expression is adopted as MU 'and YU' as an example. CU '= CU' MU '= {MU. (C0 + M0 + Y0) / (CU + MU
+ Y0)｝ · (CU '/ CU) YU' = {Y0 ・ (C0 + M0 + Y0) / (CU + M
(U + Y0)｝ · (CU ′ / CU) In step S35, one of such density corrections is adopted. The reference DUTY for performing the density correction is 25.
%, Any value can be adopted without being limited to 50%. In this case, the MU has been initially selected by the user or as a table value.

The confirmation of the process gray based on the test print result is made based on photographing data output from an optical photographing device that optically reads an image printed by the color conversion processing unit 8 without depending on visual recognition of a tester. This is possible by displaying the gray data thus obtained by numerical values. A wide variety of printing devices can be used.

FIG. 7 shows details of the color conversion processing section 8 of FIG. The screen input control unit 15, the operation device 16, the image display 18, the test print output unit 21, and the correction parameter storage unit 23 are provided in the density correction processing unit 1 shown in FIG.
The first screen input control unit 15, the operation device 16, the image display 18, the test print output unit 21, and the correction parameter storage unit 23 are used as they are. Color conversion processing unit 8
Further includes a color conversion processing unit 22 'and an image conversion control unit 27'. The color conversion processing unit 22 ′ outputs the RGB (R0, G
(0, B0) into CMY data (C0, M0, Y0). Image conversion control unit 2
Reference numeral 7 'denotes the CMY data (C0, C0, C0,
M0, Y0) and convert the CMY data (C0, M0,
(Y0) is transmitted to the density correction processing unit 11.

The image conversion control unit 27 'is provided with a color conversion processing unit 2
DUTY 25% gray (R0 = 64/255, G0 = 64/255, B0 = 6) in the color conversion table of 2 ′
4/255) (CU, MU, Y0) selected by the user based on the print result.
Change to 0). Similar conversion is performed for DUTY 50%. The color conversion table stores only discrete values and any RGB (R0, G0, B0)
If there is no value in the color conversion table corresponding to, the target color conversion processing can be performed by changing the data before and after. By providing such a color conversion processing unit 22 'in the color conversion processing unit, it is possible to correct not only gray, but also any color. In an actual driver, the color conversion processing unit and the density correction processing unit are configured by one circuit block. The density conversion can be performed by the color conversion processing unit. In this sense, the color conversion processing unit can have the same function as the density correction processing unit.

[0032]

The color correction driver and the color correction method according to the present invention can appropriately correct three-color signals from test results. Correction is optimized for a specific color, for example, gray.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing an embodiment of a color correction driver according to the present invention.

FIG. 2 is a circuit block diagram illustrating details of a density correction processing unit;

FIG. 3 is an operation flowchart showing an embodiment of a color correction method according to the present invention.

FIG. 4 is a table showing color correction.

FIG. 5 is a table showing another color correction;

FIG. 6 is a graph showing a correction function.

FIG. 7 is a circuit block diagram showing an embodiment of a name according to the present invention.

[Explanation of symbols]

 8 color conversion unit 11 color correction unit 23 correction parameter storage unit

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 2C262 AA24 AA26 AA27 AB11 BA02 BA09 BA20 BC19 EA02 FA13 5B057 AA11 BA02 CA01 CA08 CA12 CA16 CB01 CB08 CB12 CB16 CC01 CE17 CE18 CH01 CH07 5C077 LL12 MM27 MP08 PP31 PP32 PP33 PP33 PP08 5C079 HB01 HB02 HB12 KA04 LA31 LB01 MA10 MA11 MA19 NA03 PA03

Claims (11)

[Claims] 1. An image data (R0, G0, B0) represented by variables R, G, B is converted into C data represented by variables C, M, Y.
A color conversion unit for performing color conversion to MY data (C0, M0, Y0); and a color correction unit for performing color correction of the CMY data (C0, M0, Y0) to corrected CMY data (C1, M1, Y1). CMY data of the specified DYTY (C0, M0, Y
0), the plurality of corrected CMY data (C
0 + ΔCj, M0 + ΔMj, Y0 + ΔYj) and one corrected CMY data (C0 + ΔC) corresponding to one test print selected from a plurality of test prints printed based on the test prints.
k, M0 + ΔMk, Y0 + ΔYk), the CMY data (C0, M0, Y0) is added to the corrected CMY data (C
1, M1, Y1), wherein j and k are 1 to n. 2. The color correction driver according to claim 1, wherein ΔCj, ΔMj, and ΔYj can be set by a user. 3. The color correction driver according to claim 1, wherein said ΔYj is zero. 4. The color correction driver according to claim 1, wherein said DUTY is gray 25% and gray 50%, and said test printing is executed in two ways based on gray 25% and gray 50%. 5. CU = C0 + ΔCk, MU = M0 + ΔMk
Where CU, MU, and Y0 are represented by the following formula: CU ′ = CU * (C0 + M0 + Y0) / (CU + MU + Y0) MU ′ = MU * (C0 + M0 + Y0) / (CU + MU + Y0) YU ′ = Y0 * (C0 + M0 + Y0) / 5. The color correction driver according to claim 1, wherein the color correction driver is further corrected to CU ', MU', and Y0 represented by (CU + MU + Y0). 6. The method according to claim 6, wherein the CMY includes one corrected CMY data corresponding to one test print selected from a plurality of test prints printed based on a plurality of corrections in which a value of a specific DUTY is changed. Data (C0, M0,
Y0) is corrected as the corrected CMY data (C1, M1, Y1), and CU 'is selected by the user as C0. MU * (C0 + M0 + Y0) / (CU + MU
+ Y0)｝ * CU '/ CU YU' = ｛Y0 * (C0 + M0 + Y0) / (CU + MU
The color correction driver according to claim 1, wherein the color correction driver is further corrected to CU ', MU', and YU 'represented by (+ Y0)｝ * CU' / CU. 7. Image data (R0, G0, B0) represented by variables R, G, B are converted to C, M, Y represented by variables.
Color conversion into MY data (C0, M0, Y0), one or more selected from three variables C0, M0, Y0 of the specified DUTY of the specified CMY data (C0, M0, Y0) Changing the value of the selection variable in a plurality of stages; performing the multi-stage test printing on a test print sheet based on the plurality of correction selection variables in which the selection variable is changed by the change; the test Selecting one of the plurality of correction selection variables from a print result obtained by printing. 8. The specified CMY data (C0, M
8. The number of DUTY specified (0, Y0) is plural.
Color correction method. 9. One of the DUTYs is 25%, and the multiple correction selection variable of 25% is 54 / 255-54.
9. The color correction method according to claim 8, wherein the ratio is 72/255. 10. The multi-correction selection variable of 50% wherein the other one of the DUTY is 50%, is 120/255.
10. The color correction method according to claim 9, wherein 11. The color correction method according to claim 8, wherein said specified CMY data is gray.