JP2006231520A - Inkjet printer and program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain inkjet printer capable of easily performing color matching. <P>SOLUTION: A test pattern is printed by ejecting ink of each color with a density corresponding to a halftone from an ink head 16 in a carriage 15. The colorimetry of a pattern image of each color is performed by means of a chromatometer 17, so that a color difference from a reference colorimetric value can be computed. A corresponding relationship between the color difference and the correction value of a head voltage is predetermined, and the correction value is determined from the color difference according to the corresponding reference. The predetermined correction value is displayed as a recommended value on a display part 7, and the head voltage is changed when OK is input into an input part 6. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an ink jet printing apparatus and a program for forming an image by ejecting a plurality of colors of ink onto the surface of a medium.
[0002]
[Prior art]
Conventionally, ink jet printing apparatuses have been widely used for printing documents and images as printers. In recent years, printing on the surface of clothing has also been performed. In the ink jet method, an image can be easily formed even on a medium such as a fabric or a knitted fabric having a surface with an uneven surface rather than paper.
[0003]
In an ink jet printing apparatus, a head is provided for each color ink. Ink ejection is performed by a piezoelectric method in which a piezoelectric body is electrically driven to generate pressure, and a bubble method in which bubbles are generated by local boiling due to electrical heat generation in the ink and performed at that pressure. There is. Regardless of the method used, the amount of ink discharged is constant even if the head's electrical drive conditions do not change due to nozzle clogging caused by drying or deterioration of the head, or changes in ink temperature or quality. The colors in the displayed image may vary. Even if the ink ejection amount is constant, the color may vary in the finally displayed image if the ink density is different.
[0004]
When an ink jet printing apparatus is applied to printing on clothing or the like, an image to be printed is important as a design. Therefore, in mass production, it is necessary to suppress variation in color in order to stabilize quality. As a method of suppressing color variation, an endless belt-like test recording member that circulates in the ink jet recording apparatus is provided, test recording is performed for each color on the test recording member, and an image sample is formed. It has been proposed to visually recognize an image on a test recording member (see, for example, Patent Document 1). In a general color printing apparatus, a plurality of heads are operated at a fixed multi-gradation, for example, 8 gradations, and 625 colors are printed except for the vicinity of the maximum value or the minimum value of the gradation. The color variation is suppressed by creating a look-up table (LUT) and selecting a desired color.
[0005]
[Patent Document 1]
Japanese Patent Laid-Open No. 6-328724
[Problems to be solved by the invention]
In the configuration disclosed in Patent Document 1, it is described that a bubble-type ink jet recording apparatus forms a test pattern, compares it with an image sample, and adjusts thermal energy for thermoelectric conversion based on the comparison result. Yes. For example, paragraph [0028] describes that “the image density is changed and adjusted to a normal image density by changing the temperature, applied pulse width, or applied voltage of the recording head”. However, even if a difference in color is found by comparing the test pattern and the image sample, it is not known how much adjustment should be made.
[0007]
In the method of selecting a desired color from the look-up table, a large number of colors must be printed and selected. In addition, since selection must be made from among the colors included in the lookup table by visual recognition, an intermediate color or the like cannot be selected. For this reason, there is a possibility that colors vary depending on the difference between the colors in the lookup table.
[0008]
An object of the present invention is to provide an ink jet printing apparatus and a program capable of easily matching colors.
[0009]
[Means for Solving the Problems]
The present invention relates to an inkjet printing apparatus that prints an image on a medium surface by ejecting a plurality of predetermined colors of ink by electrical driving of a head provided for each color.
Driving means capable of driving each of the plurality of heads with a predetermined multi-tone, and correcting an ink ejection amount corresponding to the tone value by changing an electrical driving condition;
Control means for controlling the driving means to discharge the inks of the plurality of colors to different positions on the surface of the test medium with respective predetermined test gradations;
A colorimetric means for measuring the color of the image of the surface of the test medium with each color ink ejected at the test gradation;
Storage means for storing a correspondence relationship between correction values of electrical driving conditions with respect to a color difference from a reference value of a measured value of an image formed by ejecting ink for each color head;
The measurement result of the test gradation image formed on the surface of the test medium is input from the color measurement means, and the correspondence stored in the storage means is referenced based on the color difference from the reference value of the measurement result. In addition, the ink jet printing apparatus includes correction means for obtaining a correction value of the driving condition of the ink head of each color.
[0010]
In the invention, the test gradation is an intermediate gradation.
In the present invention, a plurality of the test gradations are set,
The correction means is characterized in that the correction value is obtained with respect to an average value of color differences for the plurality of set test gradations.
[0011]
In the present invention, a plurality of the test gradations are set,
The correction means obtains the correction value with respect to the minimum value of the color difference for the plurality of set test gradations.
[0012]
In the invention, it is preferable that the correction unit corrects an electrical driving condition of the driving unit with the correction value.
[0013]
In the invention, the correction unit displays the correction value, and corrects an electrical driving condition of the driving unit with a correction value input after the display.
[0014]
Furthermore, the present invention is an inkjet printing apparatus that prints an image on the surface of a medium by ejecting a plurality of predetermined colors of ink by electrical driving of a head provided for each color, and driving the head that ejects ink of each color. A program for causing a computer to function to output data for correcting conditions,
An input means for inputting a measurement value obtained by measuring the color of an image formed on the surface of the test medium when each of the plurality of heads is driven at a predetermined test gradation;
A calculation means for calculating a color difference between a preset reference value and an input measurement value;
Storage means for preliminarily obtaining and storing a correspondence relationship of correction values of electrical driving conditions with respect to a color difference from a reference value of a measurement value of an image formed by ejecting ink for each color head;
A program for operating a computer so as to include correction means for obtaining a correction value corresponding to the color difference calculated by the calculation means with reference to the correspondence relationship stored in the storage means.
[0015]
DETAILED DESCRIPTION OF THE INVENTION
FIG. 1 shows a schematic configuration of an ink jet printing apparatus 1 according to an embodiment of the present invention as viewed from the side rear side. The ink jet printing apparatus 1 includes a printer 2 and a control apparatus 3, and can print image data created by the design apparatus 4 or the like on a cloth or the like. As the ink, for example, disperse dye ink is used for polyester or the like, and reactive dye ink is used for cotton or wool according to the material of the fabric. Input / output to the printer 2 can be performed via the input unit 6 and the display unit 7 of the input / output panel 5. The fabric or the like that is the material to be printed is placed on the installation surface 11 at the top of the print table 10.
[0016]
Guide rails 12 and 13 are arranged on both sides of the print base 10. The guide rails 12 and 13 support the carriage beam 14. The carriage beam 14 can be reciprocated along the guide rails 12 and 13 in the X direction, which is the longitudinal direction thereof. A carriage 15 is mounted on the carriage beam 14 so as to be able to reciprocate in the Y direction which is the longitudinal direction thereof. An ink head 16 is accommodated in the carriage 15. The ink head 16 includes eight piezo-type heads capable of ejecting cyan, magenta, yellow, and black CMYK four colors as ink jets for each dark or light color. A colorimeter 17 is also mounted on the side surface of the carriage 15, and the color of an image formed with ink ejected from the ink head 16 can be measured. The ink ejected from the ink head 16 is supplied from the ink tank 18 arranged side by side on the back side of the print table 10 to the carriage 15. The ink tanks 18 are arranged for the aforementioned eight colors, and a cleaning liquid tank 19 for supplying a cleaning liquid for cleaning the ink head 16 is also arranged.
[0017]
Design data for printing by the ink jet printing apparatus 1 can be created by the design apparatus 4. The design device 4 includes a computer 20 and a display 21. The image data created by the design device 20 can be transferred to the control device 3 of the ink jet printing apparatus 1 via a wired or wireless communication path, or can be temporarily written to a flexible disk (FD), a magneto-optical disk (MO), or the like. It is recorded on a recording medium such as a simple optical disc, and is read by the control device 3 and input.
[0018]
In the ink jet type ink head 16, the electric voltage such as the driving voltage is changed due to aging deterioration of the piezo element, nozzle clogging, ink drying, ink viscosity and piezo element characteristic change due to temperature change, ink quality change, and the like. Even if the general driving conditions are the same, the ink discharge amount is not constant. In the ink jet printing apparatus 1 of the present embodiment, a test pattern is printed by the ink head 16, an image of each color is measured by the colorimeter 17, and the driving condition is corrected based on the measurement result. The colorimeter 17 can be built in the carriage 15 or installed outside the printer 2.
[0019]
FIG. 2 shows an example of the test pattern 30. Such a test pattern is printed on the surface of a medium such as test paper. The material to be printed can also be used as a test medium. The ink head 16 is electrically driven by a drive circuit capable of changing the ink discharge amount with 8 bits, that is, 255 gradations. This gradation drive is performed by changing the pulse width of a pulse for driving the piezo element. The density of the image to be printed is changed based on the error diffusion method, the dots formed by ink ejection are dispersed, and multiple gradations are displayed as a whole of multiple dots, and the gradation difference between individual dots can be reduced. it can.
[0020]
As described above, since the inks of eight colors obtained by adding the difference in density to the four colors of CMYK are used, the pattern image corresponds to eight colors. In the present embodiment, for example, a pattern image is formed with two intermediate gradations of 96 gradations and 64 gradations out of 255 gradations. That is, in 96 gradations, eight pattern images 31DC, 31DM, 31DY, 31DK, 31LC, 31LM, 31LY, 31LK of dark cyan, dark magenta, dark yellow, dark black, light cyan, light magenta, light yellow, and light black are used. Respectively. Similarly, in 64 gradations, eight pattern images 32DC, 32DM, 32DY, 32DK, 32LC, 32LM, 32LY, dark cyan, dark magenta, dark yellow, dark black, light cyan, light magenta, light yellow, and light black are used. Each of 32LK is formed. The specific 96 or 64 gradation values may be other values. In addition, although it is possible to use one intermediate gradation instead of two kinds of gradations, or three or more gradations, it is preferable to test with two gradations in terms of both labor and accuracy.
[0021]
FIG. 3 shows a schematic electrical configuration of the ink jet printing apparatus 1 of FIG. The control device 3 includes a control unit 40 that performs overall control as the printer 2, a storage unit 41 that stores data, and a communication unit 42 that performs data communication with the outside. The control device 3 further includes a power supply circuit 43 and a drive circuit 44. The drive circuit 44 electrically drives a piezo element 45 provided for each color in the ink head 16 in the carriage 15. Data for gradation display is created by the control unit 40 and given to the drive circuit 44. The drive condition can be corrected by adjusting the voltage to the drive circuit 44 that drives each piezo element 45 from the power supply circuit 43. For the movement of the carriage 15, a controller 46 is provided in the control device 3, and an X motor 47 that moves the carriage beam 14 along the guide rails 12 and 13 and a Y motor 48 that moves the carriage 15 along the carriage beam 14 are provided. Can be controlled.
[0022]
The control unit 40 also has a function of controlling input by an input operation performed on the input unit 6 of the input / output panel 5 and output by the display unit 7 of the input / output panel 5. Furthermore, a function for obtaining a correction value of a voltage for adjusting the power supply circuit 43 with reference to the storage unit 41 based on the measurement result from the colorimeter 17 is also provided.
[0023]
FIG. 4 shows a schematic color matching procedure by the control unit 40 of FIG. In step s0, for example, when a specific switch provided in the input unit 6 is operated, the procedure is started. In step s1, a voltage adjustment dialog is displayed on the display unit 7. In the voltage adjustment dialog, enter the ink type. In step s2, the calorimeter 17 is calibrated. For example, in the L *, a *, and b * colorimetry systems, the reference color is calibrated.
[0024]
In step s3, sample printing for printing the test pattern 30 and the like in FIG. 2 is performed. In step s4, the pattern images 31DC, 31DM, 31DY, 31DK, 31LC, 31LM, 31LY, 31LK, 32DC, 32DM, 32DY, 32DK, 32LC, 32LM, 32LY, and 32LK of the sample printed test pattern 30 are viewed. The operator determines whether it is OK. If it is determined that the color is not preferable, for example, it is determined that the color is not OK, the process proceeds to step s5, and the colorimetry 17 performs colorimetry of 16 colors of CMYK while moving the carriage 15 so that the colorimetry can be performed. .
[0025]
The color measurement of each pattern image 31DC, 31DM, 31DY, 31DK, 31LC, 31LM, 31LY, 31LK, 32DC, 32DM, 32DY, 32DK, 32LC, 32LM, 32LY, 32LK is performed a plurality of times while changing the position. It is preferable. If a plurality of color measurement results are subjected to statistical processing such as average value calculation, the influence of print unevenness can be avoided.
[0026]
In step s6, a color difference with respect to the reference color is calculated from the color measurement result, a recommended value as a correction value to be given to the power supply circuit 43 is set based on the correspondence stored in the storage unit 41, and the display unit 7 indicate. In step s7, it is determined whether or not the operator who has seen the recommended value displayed on the display unit 7 inputs the voltage change OK to the input unit 6. If the voltage change is OK, the recommended voltage is set in the power supply circuit 43 in step s8, the process returns to step s3, and the result of the sample print is confirmed. If it is determined in step s4 that the color of the sample print is OK, the procedure ends in step s9. When it is determined in step s7 that the voltage change is not OK, the procedure is ended in step s9.
[0027]
In the above procedure, the result of the sample print in step s4 is determined by a person such as an operator. However, after the sample print in step s3, the process proceeds to the colorimetry in step s5. It is also possible to automatically change the voltage up to s8. In step s7, after the recommended voltage is displayed, when the operator performs an input operation to change the recommended value from the input unit 6, the changed recommended voltage may be set in step s8. Further, instead of correcting the voltage of the power supply circuit 43, the pulse width of a pulse for driving the piezo element 45 may be corrected.
[0028]
FIG. 5 shows an example of statistical data stored in advance in the storage unit 41 of FIG. FIG. 5A shows the actual measurement result for the dark cyan density for the 96 gradation pattern image 31DC. The change in the L * value when the head voltage is changed from the standard voltage in the positive or negative direction is measured. FIG. 5B shows statistical data calculated by averaging the actually measured data of FIG. If the L * value is taken on the y axis and the head voltage correction value is taken on the x axis, it can be seen that the piezo element 45 of the dark cyan head has the correction characteristic of the following equation (1). The storage unit 41 stores data of the formula (1).
y = 8.875x + 44.0 (1)
[0029]
In the L * a * b * colorimetry system, the L * value is the value of the brightness of the object and ranges from 0 (black) to 100 (white). Further, a * indicates a positive degree of red and a negative degree of green. b * indicates a positive degree of yellow and a negative degree of blue. Further, an Lch system that converts the L * value into the L value and the a * value and b * into the following equations (2) and (3) is also used.
c = √ (a * × a * + b * × b *) (2)
h = atan (b * / a *) × 180.0 / π (3)
[0030]
For example, assuming that the voltage applied to the piezo element 45 of the head of dark cyan ink is 23.5 V, and the sample print at step s3 in FIG. 4 is measured at step s5, L * value is obtained at 96 gradations. , A * value and b * value are 52.197, -26.812 and -22.281, respectively, and at 64 gradations, the L * value, a * value and b * value are 70.775 and -31. 787, -25.475. In the equation (1), the standard L * value is 44.0, and the L * value for 96 gradations is 52.197 as described above, so the color difference for the L * value is 8.197. Thus, x = 8.917 ÷ 8.875 = 0.9236.
[0031]
Assuming that the statistical data of y = 7.762x + 68.01 is obtained in the same calculation as described above for 64-gradation printing, the color difference is 70.775−68.01 = 2 from y = 70.775. .765, and x = 2.765 ÷ 7.762 = 0.3562.
[0032]
Since L * is higher than the standard, the head voltage applied from the power supply circuit 43 to the piezo element 45 of the dark cyan head should be lowered by 0.6399 V which is the average value of 96 gradations and 64 gradations. I understand. Actually, the correction may be performed in units of 0.1V, and the head voltage may be reduced by 0.6V to 22.9V.
[0033]
Such correction based on the color difference based on the L * value is effective for the C, M, and K heads. For the Y head, the c value is more preferable than the L * value because the slope of the straight line becomes more prominent, and the same calculation may be performed by using the c value.
[0034]
FIG. 6 shows an example of a screen that displays a recommended value for voltage change for color difference adjustment displayed in step s7 of FIG. As the calculation standard, “average” instructs to take the average of 96 gradations and 64 gradations as described above, and “minimum value priority” instructs to give priority to the one having a smaller color difference. Even if the color differences at a plurality of test gradations fluctuate, the correction value is obtained for the minimum value, so that excessive correction can be prevented.
[0035]
As described above, the inkjet printing apparatus 1 according to the present embodiment ejects a plurality of predetermined ink colors by electrically driving a head provided for each color, and prints an image on the medium surface. The driving circuit 44, which is a driving unit capable of correcting the ink discharge amount corresponding to the gradation value by changing the electrical driving condition, and the driving circuit 44 can be controlled. Then, the control unit 40 as control means for ejecting the plurality of colors of ink to different positions on the surface of the test medium with predetermined test gradations, and the inks of the respective colors ejected with the test gradations The color from the reference value of the measured value of the image formed by ejecting ink with respect to the colorimeter 17 as a color measuring means for measuring the color of the image of the surface of the test medium according to each of the above and the head of each color On the other hand, the storage unit 41 as a storage unit that stores the correspondence relationship between the correction values of the electrical driving conditions, and the test gradation image formed on the surface of the test medium from the colorimeter 17. Control as correction means for inputting the measurement result and referring to the correspondence stored in the storage unit 41 based on the color difference from the reference value of the measurement result to obtain the correction value of the drive condition of the ink head of each color Part 40.
[0036]
In this embodiment, the piezo elements 45 of the heads of the respective colors are respectively driven by the drive circuit 44 to form a single color image of the test gradation on the surface of the test medium, and the colorimeter 17 Measure the color of the image. The correction value of the electrical drive condition for the color difference from the reference value of the measurement value of each color image is stored in the storage unit 41, and the control unit 40 as the correction unit measures the measurement result of the colorimeter 71. Since the correction value corresponding to the color difference is obtained with reference to the storage unit 41 based on the color difference obtained from the above, what kind of correction is to be performed can be specifically obtained. Since the color difference is measured by the colorimeter 17, it can be measured more accurately than visual recognition, even with a difference that is invisible to the human eye.
[0037]
Furthermore, the present invention is installed in the computer 20 or the like of the design apparatus 4 in FIG. 1, and a plurality of predetermined colors are ejected by the electrical drive of a head provided for each color, and an image is printed on the surface of the medium. It can also be realized as a program for causing the computer 20 to function so as to output data for correcting the driving conditions of the head that ejects ink of each color in the ink jet printing apparatus.
[0038]
This program includes an input means for inputting a measurement value obtained by measuring the color of an image formed on the surface of a test medium when driving a plurality of heads with predetermined test gradations, and a reference value set in advance. The calculation means for calculating the color difference from the input measurement value and the correction value of the electrical driving condition for the color difference from the reference value of the measurement value of the image formed by ejecting ink for each color head. Storage means for obtaining and storing the correspondence relationship in advance, and correction means for obtaining a correction value corresponding to the color difference calculated by the calculation means with reference to the correspondence relationship stored in the storage means, The computer 20 is operated. When a measurement value obtained by measuring the color of an image formed on the surface of a test medium when a plurality of heads are driven with predetermined test gradations is input to the computer 20 on which the program operates, a preset reference is set. A color difference between the value and the input measurement value is calculated, and a correction value for the electrical driving condition can be obtained based on the stored correspondence relationship.
[0039]
Note that changing the driving conditions based on the above-described concept can be similarly applied to ink jet printing apparatuses other than the piezoelectric type, such as a bubble type.
[0040]
【The invention's effect】
As described above, according to the present invention, a plurality of color inks, each color head is driven by the driving means, and a single-color image of the test gradation is formed on the surface of the test medium. Measure the color. The correction value of the electrical driving condition for the color difference from the reference value of the measured value of each color image is stored in the storage means, and the correction means is based on the color difference obtained from the measurement result of the color measuring means. Since the correction value corresponding to the color difference is obtained by referring to the storage means, it is possible to specifically obtain what kind of correction is performed and to easily match the colors. Since the color difference is measured by the colorimetric means, it can be measured more accurately than visual recognition, even with a difference that cannot be recognized by the human eye.
[0041]
In addition, according to the present invention, the electrical drive condition is corrected with an intermediate gradation as the test gradation, so that the difference between the maximum gradation and the vicinity of the minimum gradation is not a conspicuous gradation, and the difference is Color variations can be adjusted with a conspicuous gradation.
[0042]
Further, according to the present invention, since the correction value is obtained for the average value of the color differences measured at a plurality of test gradations, the overall color variation can be suppressed.
[0043]
Further, according to the present invention, even if the color difference at a plurality of test gradations fluctuates, the correction value is obtained for the minimum value, so that excessive correction can be prevented.
[0044]
Further, according to the present invention, the correction means corrects the electrical drive condition of the drive means for driving the head with the obtained correction value, so that the correction based on the color difference can be automatically performed.
[0045]
Further, according to the present invention, the correction means displays the obtained correction value, and corrects the electrical drive condition of the drive means with the correction value input by the operation after the display or the like. The correction value can also be corrected.
[0046]
Further, according to the present invention, when a measurement value obtained by measuring the color of an image formed on the surface of the test medium is input to the computer when each of the plurality of heads is driven at a predetermined test gradation, the preset value is set in advance. The color difference between the reference value and the input measurement value is calculated, and the correction value of the electrical drive condition can be obtained based on the stored correspondence relationship. Brief description of]
FIG. 1 is a perspective view showing a schematic configuration of an ink jet printing apparatus 1 according to an embodiment of the present invention.
FIG. 2 is a diagram illustrating an example of a test pattern 30 for performing color matching in the ink jet printing apparatus 1 of FIG.
FIG. 3 is a block diagram showing a schematic electrical configuration of the ink jet printing apparatus 1 of FIG. 1;
4 is a flowchart showing a schematic color matching procedure by the control unit 40 of FIG. 3;
FIG. 5 is a graph showing an example of statistical data stored in advance in a storage unit 41 of FIG. 3;
6 is a diagram showing an example of a screen that displays a recommended value for voltage change for color difference adjustment displayed in step s7 of FIG. 4; FIG.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Inkjet printing apparatus 2 Printer 3 Control apparatus 4 Design apparatus 6 Input part 7 Display part 10 Print stand 15 Carriage 16 Ink head 17 Colorimeter 18 Ink tank 20 Computer 30 Test pattern 31DC, 31DM, 31DY, 31DK, 31LC, 31LM , 31LY, 31LK, 32DC, 32DM, 32DY, 32DK, 32LC, 32LM, 32LY, 32LK Pattern image 40 Control unit 41 Storage unit 43 Power supply circuit 44 Drive circuit 45 Piezo element

Claims (7)

In an ink jet printing apparatus that prints an image on the surface of a medium by ejecting a plurality of predetermined colors of ink by electrical driving of a head provided for each color,
Driving means capable of driving each of the plurality of heads with a predetermined multi-tone, and correcting an ink ejection amount corresponding to the tone value by changing an electrical driving condition;
Control means for controlling the driving means to discharge the inks of the plurality of colors to different positions on the surface of the test medium with respective predetermined test gradations;
A colorimetric means for measuring the color of the image of the surface of the test medium with each color ink ejected at the test gradation;
Storage means for storing a correspondence relationship between correction values of electrical driving conditions with respect to a color difference from a reference value of a measured value of an image formed by ejecting ink for each color head;
The measurement result of the test gradation image formed on the surface of the test medium is input from the color measurement means, and the correspondence stored in the storage means is referenced based on the color difference from the reference value of the measurement result. And a correction means for determining a correction value of the driving condition of the head of each color ink.   2. The ink jet printing apparatus according to claim 1, wherein the test gradation is an intermediate gradation. A plurality of the test gradations are set,
The ink jet printing apparatus according to claim 1, wherein the correction unit obtains the correction value with respect to an average value of color differences for the plurality of test gradations set. A plurality of the test gradations are set,
3. The ink jet printing apparatus according to claim 1, wherein the correction unit obtains the correction value with respect to the minimum value of the color difference for the plurality of set test gradations.   The ink jet printing apparatus according to claim 1, wherein the correction unit corrects an electrical driving condition of the driving unit with the correction value.   The inkjet type according to claim 1, wherein the correction unit displays the correction value, and corrects an electrical driving condition of the driving unit with a correction value input after the display. Printing device. Data that corrects the driving conditions of the head that ejects ink of each color in an ink jet printing device that prints an image on the surface of a medium by ejecting multiple predetermined colors of ink by electrical driving of the head provided for each color A program for operating a computer to output
An input means for inputting a measurement value obtained by measuring the color of an image formed on the surface of the test medium when each of the plurality of heads is driven at a predetermined test gradation;
A calculation means for calculating a color difference between a preset reference value and an input measurement value;
Storage means for preliminarily obtaining and storing a correspondence relationship of correction values of electrical driving conditions with respect to a color difference from a reference value of a measurement value of an image formed by ejecting ink for each color head;
A program for operating a computer so as to include correction means for obtaining a correction value corresponding to the color difference calculated by the calculation means with reference to the correspondence relationship stored in the storage means.

Images