JP2007266842A - Color correction device, color correction method, and color correction program - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem wherein it is difficult for a user to obtain his/her ideal color printing result, and delicate variation exists in colors at printing result for each group of printing equipments different in a date of manufacturing for parts. <P>SOLUTION: While acquiring colorimetric result of patch printed respectively by a plurality of printing equipments based on a common tone data, representative colorimetric result for representing each colorimetric result is computed based on each of the colorimetric result. According to a value of the representative colorimetric result, a correction rule of tone data is determined for correcting color shift between printing result by the plurality of printing equipments and printing result by a desired reference printing equipment used a color correction reference. Using the determined correction rule, tone data representing an arbitrary image is corrected, and a printing equipment which printed the patch is directed to perform printing based on the tone data after the correction. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a color correction apparatus, a color correction method, and a color correction program for correcting the color of a print image by a printing apparatus.

Conventionally, when an image is printed on a printing apparatus having a print head that ejects ink dots based on image data that represents the image with gradation values for each pixel, the dots ejected by the print head of the printing apparatus Information (head ID) representing the deviation between the ink amount of the ink and the dot ink amount as the design standard is acquired, and the image data is corrected with the correction information corresponding to the deviation, and the corrected image data is obtained. Based on the printing. In other words, the head ID is prepared in advance for each printing apparatus at the manufacturing stage, and the gradation value of the image data is increased or decreased according to the value of the head ID at the time of printing, so that the ink amount of the dots to be ejected is increased. Even if a print head having a deviation from the design standard is used, an ideal color can be printed to some extent.
As such a type of color correction technology, an inkjet printer including an information retrieval device that reads droplet volume information related to an inkjet print head, which compensates for manufacturing tolerances using this volume information is known. (See Patent Document 1).

As another method for color correction of printed matter, the amount of ink used in the ink cartridge is acquired during the printing process, the degree of ink variation is obtained from the amount used, and the correction according to the degree of variation is performed. A technique for correcting the print density by correcting the color conversion table LUT using a coefficient is known (see Patent Document 2). According to this technique, it is possible to prevent variations in print density that occur due to changes in ink density over time.
Japanese Patent Laid-Open No. 10-119315 Japanese Patent Laid-Open No. 2002-292836

In the conventional color correction, the color used as a reference for color correction is basically determined by the manufacturer of the printing apparatus, and correction information etc. is set so that the reference color is reproduced in the print result. In each printing apparatus, image data and the like are corrected.
However, if the ideal color that the user wants to use as the reference for color correction is different from the standard color determined by the manufacturer, that is, the color reproducibility of the printing device that is ideal for the manufacturer and the color that is ideal for the user If there is a difference, the conventional color correction has a disadvantage that printing of the color that the user really wants cannot be performed. Furthermore, there are cases where the user has a plurality of printing apparatuses, and for the plurality of printing apparatuses, a color reproducibility that is different from the ideal color reproducibility desired by the manufacturer is desired.

  Further, each printing apparatus mass-produced every day has a deviation from the standard in its color reproduction capability for each individual machine. For this reason, the above-described setting of the head ID and the like is performed for each printing apparatus. However, the mass-produced printing apparatuses have some common features such as the manufacturing time and the procurement time of the parts used. The color reproducibility tends to be different for each group. However, such a peculiar shift in the group unit of the printing apparatus is not completely eliminated even if the color correction for each individual machine described above is executed, and in this respect, a highly accurate color in the printed matter. It was hard to say that the correction was realized.

  SUMMARY An advantage of some aspects of the invention is that it provides a color correction device, a color correction method, and a color correction program capable of realizing a desired color reproduction with extremely high accuracy in a print result. To do.

  In order to achieve the above object, the color correction apparatus according to the present invention corrects color misregistration in a print image that is printed on the basis of predetermined gradation data by a printing apparatus including a print head that ejects dots. Here, the calculation means obtains the color measurement results of the patches respectively printed based on the common gradation data for a plurality of printing apparatuses, and the representative representing each color measurement result based on each color measurement result Calculate the color measurement result. The plurality of printing apparatuses referred to here means each printing apparatus belonging to a certain group when printing apparatuses that are mass-produced are grouped according to predetermined conditions. For example, the grouping can be performed according to the manufacturing time of the printing apparatus. The representative color measurement result is a value representing the tendency of color shift of each print result by the plurality of printing apparatuses, and the representative color measurement result is stored as data in each of the plurality of printing apparatuses. The correction rule determining means is a gradation for correcting color misregistration between a printing result by the plurality of printing devices and a printing result by a desired reference printing device as a color correction reference according to the value of the representative colorimetry result. Determine correction rules for data.

  The desired reference printing device may be, for example, a printing device as a product design standard determined in advance by the manufacturer of the printing device, or a printing device selected by the user according to his / her preference. There may be. Then, the printing control unit corrects the gradation data representing an arbitrary image using the determined correction rule, and the printing control unit prints the patch based on the corrected gradation data. The arbitrary image is printed. Here, various methods for calculating the representative color measurement results can be considered. As an example, the calculation means averages the color measurement results of the patches printed on the plurality of printing apparatuses, and the average value is also used as the representative color measurement result. Good.

  As described above, according to the present invention, one index value called a representative colorimetric value is calculated based on the printing results of a plurality of printing apparatuses, and a gradation data correction rule is determined based on the representative colorimetric value. Therefore, even when each of the plurality of printing apparatuses is subjected to color correction, a common representative color value and correction rule can be used, and the color correction processing for the plurality of printing apparatuses is made efficient. In addition, since the determined correction rule is to correct color misregistration with a desired reference printing apparatus, the color that the user really wants is reproduced in the print result based on the corrected gradation data. It will be.

  Here, there may be variations in the ink amount of the ejected dots for each print head included in each of the plurality of printing apparatuses, and it is necessary to consider the influence of such variations in order to achieve ideal color reproducibility in the printed matter. There is. Therefore, when the patch is printed on each of the plurality of printing devices, the calculation unit obtains a deviation between the ink amount of dots ejected by the print head included in each printing device and the design reference amount of the ink amount of dots, The common gradation data may be corrected according to each acquired deviation. That is, the patch is printed in a state in which the color shift of the printed matter due to the influence of the shift of the dot ink amount for each printing apparatus is corrected. For this reason, the color measurement results of the patches printed by a plurality of printing apparatuses are basically close to each other. Accordingly, the representative color measurement result calculated from each color measurement result is also a value representing the tendency of color misregistration of each print result by the plurality of printing apparatuses almost accurately, and using such a representative color measurement result, A correction rule that is more suitable for correcting color misregistration in the plurality of printing apparatuses can be determined.

  Even in the case of mass production of the same type of printing apparatus, the production lots of predetermined parts constituting the printing apparatus may be different due to differences in parts procurement units and production timing. In addition, between printing apparatuses having different production lots for a given part, the degree of color shift from the reference color in the printed matter is different. On the other hand, between printing apparatuses having the same production lot for the given part, printed matter There is a tendency that the degree of color misregistration with the reference color is similar. Therefore, as another configuration of the present invention, the calculation unit may calculate a representative color measurement result based on a color measurement result of a patch printed on a plurality of printing apparatuses having a common manufacturing lot of a predetermined part. . The representative colorimetric result calculated from the colorimetric results of each patch printed on a plurality of printing devices with the same manufacturing lot is a color shift from the reference color of each printing result by the plurality of printing devices with the same manufacturing lot. It is a value that expresses the tendency of Therefore, using such a representative color measurement result, it is possible to determine a correction rule that is extremely suitable for correcting color misregistration of each printing result by a plurality of printing apparatuses having the same manufacturing lot.

  Among the various parts of the printing apparatus, the performance of the print head greatly affects the color of the printed matter, and the performance varies depending on the production lot of the print head. Therefore, the calculation unit may print the patches on a plurality of printing apparatuses having a common print head manufacturing lot, and calculate the representative color measurement results based on the color measurement results of the patches. That is, the printing apparatuses are grouped according to whether or not the print head production lots are common, and one representative color measurement result is set for each group. By using such representative color measurement results, it is possible to determine an optimal correction rule for correcting color misregistration that appears in a similar tendency in the print results of a plurality of printing apparatuses belonging to the group.

  The color correction device is provided in the comparative printing device in which color misregistration occurs between a color measurement result and a printing result of a plurality of reference patches printed on the reference printing device based on specific gradation data and a printing result by the reference printing device. A correction rule for gradation data obtained from the result of comparison with the colorimetric results of a plurality of comparison patches printed based on gradation data of a plurality of stages including specific gradation data, and the common gradation data Based on the color measurement results of the patches printed on the reference printing device and the comparative printing device based on the above, a correction rule determination function that can determine a correction rule according to the value of any representative color measurement result is generated in advance However, it may be provided in a predetermined storage area. Then, the correction rule determination means determines the correction rule by referring to the correction rule determination function. That is, the representative color measurement result calculated by the calculation means is input to the correction rule determination function, and a correction rule corresponding to the representative color measurement result is acquired. According to this configuration, in each of a plurality of printing apparatuses having the same representative color measurement result, a correction rule for correcting gradation data is simplified so that a printing result having a color equivalent to the printing result by the reference printing apparatus can be printed. Can be obtained.

  When the printing apparatus can eject a plurality of dot types having different ink amounts per droplet, when the printing apparatus performs printing based on gradation data representing an image, the gradation data is It is necessary to convert the data into dot type gradation data expressing the recording amount for each of a plurality of dot types. Therefore, as one of the specific methods when correcting the gradation data according to the correction rule, the print control unit corrects only the gradation data for each dot type related to a specific dot type among the dot types. May be performed. In this manner, by dividing whether or not correction is performed for each gradation data for each dot type, the degree of color correction in the print result can be finely controlled.

So far, the invention has been described by the category of color correction apparatus, but the contents of the color correction apparatus can be grasped as procedures executed by each means, and as a result, can be grasped as an invention of a color correction method.
Similarly, the contents of the color correction apparatus can be grasped as an invention of a color correction program that causes a computer to execute the procedure executed by each means.

Embodiments of the present invention will be described in the following order.
(1) Outline of color correction device (2) Generation of correction rule determination function (3) ID setting for mass production printer (4) Print control processing (5) Change of standard printer

(1) Outline of Color Correction Device FIG. 1 shows a computer 10 or the like corresponding to a color correction device according to the present invention.
In the computer 10, the CPU 11 which is the center of the arithmetic processing controls the entire computer 10 via the system bus 10a. The bus 10 a is connected to a ROM 12 that is a non-rewritable semiconductor memory, a RAM 13 that is a rewritable semiconductor memory, and various interfaces (I / F) 17 a to 17 d, and a magnetic disk via a hard disk drive (HDDRV) 15. A hard disk (HD) 14 is also connected.

  The HD 14 stores an operating system (OS), an application program (APL), and the like, which are appropriately transferred to the RAM 13 by the CPU 11 and executed. The HD 14 stores the color correction program of the present invention, and the HD 14 stores correction rule determination functions F and F ′, a color conversion lookup table (LUT) 14a, a dot distribution table 14b, and the like. It is a storage area.

The colorimeter 40 is connected to the I / F 17a (for example, USB I / F). The colorimeter 40 directs the color detection unit 40a to the object to be colorimetrically measured so as to be in the L ^* a ^* b ^* color system (hereinafter, “ ^* ” is omitted) defined by the International Lighting Commission (CIE). The values of a plurality of color components L, a, and b based on it can be acquired as colorimetric data, and the acquired colorimetric data can be output to the computer 10. Here, the Lab color space is a uniform color space independent of the device. Of course, color space colorimetry, CIE defines the L ^* u ^* v ^* color space, XYZ color space of the CIE defined, it may be an RGB color space or the like. Note that patch colorimetry described later is not limited to using the colorimeter 40, and a scanner or the like may be used.

  A display 18a for displaying an image corresponding to the data based on the image data is connected to the I / F 17b. A keyboard 18b and a mouse 18c are connected to the input I / F 17c as operation input devices, and are connected to the printer I / F 17d. For example, the printer 20 is connected via a serial I / F cable.

  The printer 20 is a printing apparatus controlled by the computer 10, and the configuration thereof is a mass production printer 20b described later, a reference printer 20a serving as a design standard for the mass production printer 20b, a first comparison printer, and a second comparison printer. And in common. Therefore, in FIG. 1, one printer 20 is shown as a representative of the above-mentioned printers. The printer 20 fills a plurality of ink cartridges 28 respectively corresponding to a plurality of ink types (in this embodiment, cyan (C), magenta (M), yellow (Y), and black (K) inks are used). The ejected ink is ejected as dots (ink droplets) from a plurality of nozzle rows 29a to 29d provided corresponding to the respective ink types in the print head 29, so that a print image corresponding to the image data on the print paper To print. However, the type and number of inks used are not limited to the above types, and various inks such as light cyan, light magenta, light black, dark yellow, red, violet, and non-colored ink can be used. In addition, various printers such as a bubble type printer that generates bubbles in the ink passage and discharges ink, and a laser printer that prints a print image on printing paper using toner ink can be employed. The ink used by the printer may be liquid or solid

In the printer 20, a CPU 21, a ROM 22, a RAM 23, a communication I / O 24, a control IC 25, an ASIC 26, an I / F 27 and the like are connected via a bus 32, and the CPU 21 controls each unit according to a program written in the ROM 22.
The print head 29 includes a nonvolatile semiconductor memory 31. The memory 31 can be an EEPROM or the like, and records a lot ID or the like acquired in an ID setting process described later. Each cartridge 28 is provided with a memory chip 28a made of, for example, RAM, and each memory chip 28a is electrically connected to the control IC 25.

  The communication I / O 24 is connected to the printer I / F 17d of the computer 10, and the printer 20 receives the raster data for each ink type transmitted from the computer 10 via the communication I / O 24. The ASIC 26 outputs applied voltage data corresponding to the raster data to the head driving unit 26a while transmitting / receiving a predetermined signal to / from the CPU 21. The head drive unit 26a generates an applied voltage pattern (drive waveform) to the piezo elements built in the nozzle arrays 29a to 29d of the print head 29 from the applied voltage data, and the ink of each ink type is applied to the print head 29. Are ejected in dot units.

  A carriage mechanism 27 a is connected to the I / F 27. The carriage mechanism 27 a is a drive device that reciprocates a carriage (not shown) along a guide rail (not shown) provided in the printer 20. Each ink cartridge 28 and print head 29 are mounted on the carriage, and as a result, each ink cartridge 28 and print head 29 reciprocate along the guide rail. The paper feeding mechanism 27b conveys the printing paper at a predetermined speed in a direction substantially perpendicular to the reciprocating direction of the carriage by a paper feeding roller (not shown).

Each of the nozzle rows 29a to 29d is a set of a plurality of inkjet nozzles (simply referred to as nozzles), and a piezoelectric element is arranged corresponding to each of the nozzles.
As shown in FIG. 2, the piezo element PE is installed at a position in contact with the ink passage 25b that guides ink to the nozzle Nz, and when a voltage having a predetermined time width is applied between the electrodes provided at both ends of the piezo element PE. Then, the voltage is extended for the time of voltage application, and one side wall of the ink passage 25b is deformed. As a result, the volume of the ink passage 25b contracts in accordance with the expansion of the piezo element PE, and the ink corresponding to the contraction becomes an ink droplet Ip and is ejected from the tip of the nozzle Nz at high speed.

  This figure shows an example of a drive waveform V for forming a predetermined number of types of dots having different dot sizes (ink amount per dot, or dot diameter), and a small waveform v1 for a predetermined period. , V2 are formed depending on whether or not the ink amount is generated. Here, as the voltage difference between the small waveforms increases, the degree of expansion and contraction of the piezo element increases. When only the small waveform v1 is generated, when only the small waveform v2 is generated, both the small waveforms v1 and v2 are changed. In the order of generation, the ink amount of the ejected dots increases stepwise. That is, in this embodiment, the printer 20 can eject three types of dots, small dots, medium dots, and large dots, from each nozzle by properly using the generation of the small waveforms v1 and v2. The raster data transmitted from the computer 10 to the printer 20 is added with identification information for identifying the dot type. When the raster data representing the dot type is input for each raster, the printer 20 corresponds to the raster data. A plurality of types of dots having different ink amounts are formed on the printing paper.

(2) Generation of Correction Rule Determination Function In this embodiment, the computer 10 first performs a process of generating the correction rule determination function F in order to correct the color misregistration of the printed matter by the mass production printer 20b. The correction rule determination function F is a function for determining a correction rule according to the value of the printer ID (lot common printer ID) set for each mass production printer 20b.
FIG. 3 schematically shows an example of a system suitable for generation of the correction rule determination function F and ID setting processing for the mass production printer 20b described later. According to the figure, a colorimeter 40 is connected to the computer 10. Further, a reference printer 20a, a first comparison printer, a second comparison printer, and a mass production printer 20b are connected to the computer 10 as appropriate.

FIG. 4 is a flowchart showing the content of the generation process of the correction rule determination function F executed by the computer 10. This process is executed according to the color correction program.
In step S (hereinafter, step notation is omitted) 100, the computer 10 in the state where the reference printer 20a is connected, at least based on the reference patch image data (tone value n0). ) To print a reference patch including a patch of only a specific ink type corresponding to the print paper on the printing paper. The reference patch image data is image data in which the ink recording amount for each ink type (CMYK) for each pixel is expressed in gradation (expression by 256 gradations from 0 to 255), and at least by the gradation value n0. This is data representing patches based only on the specific ink type. In the present embodiment, the reference patch image data is data representing a C single color patch corresponding to at least the gradation value n0. The gradation value n0 corresponds to specific gradation data described in the claims.

  The computer 10 reads the reference patch image data stored in advance in the HD 14 from the HD 14, and performs predetermined halftone processing and rasterization processing on the reference patch image data, and generates the generated raster data. By sending the data to the reference printer 20a, the reference printer corresponding to the image data for reference patch is printed on the reference printer 20a. In step S <b> 110, the color measurement is performed on the reference patch printed on the printing paper by the colorimeter 40, and the computer 10 inputs the colorimetric data (Lab value) obtained by the color measurement from the colorimeter 40. The color measurement data of the reference patch is stored in the HD 14. As described above, since the reference printer 20a is a machine that serves as a design reference for the mass production printer 20b, the color measurement data of the reference patch printed by the reference printer 20a is the reference color for color correction.

  In S120, the computer 10 is connected to each of the first comparison printer and the second comparison printer based on the comparison patch image data in a state where the computer 10 is connected to the first comparison printer and the second comparison printer. Thus, a process of printing a plurality of patches only with the specific ink type corresponding to the gradation values of a plurality of stages on the printing paper is performed. The comparison patch image data is image data in which the ink recording amount for each ink type is expressed in gradation for each pixel, and image data in which a plurality of patches of only the specific ink type are expressed by a plurality of gradation values. It is. The plurality of gradation values include the specific gradation value n0.

  In the case of the above-mentioned multiple levels of gradation values, it may mean all the gradations of 256 gradations, or may be a plurality of gradation values within a predetermined range including the gradation value n0. Further, the first comparison printer is a printer of the same type as the reference printer 20a, but is a machine body in which the amount of ink of ejected dots tends to be larger than that of the reference printer 20a. The second comparison printer is It is assumed that the printer is the same type as the reference printer 20a, but the machine body has a tendency that the ink amount of ejected dots is smaller than that of the reference printer 20a.

Hereinafter, the patch printed on the first comparison printer is called a first comparison patch, and the patch printed on the second comparison printer is called a second comparison patch.
In S <b> 130, the plurality of first comparison patches and the plurality of second comparison patches printed on the printing paper are respectively measured by the colorimeter 40, and the computer 10 measures the colorimetric data ( (Lab value) is input from the colorimeter 40. The color measurement data of the first comparison patch and the second comparison patch are stored in the HD 14.

  In S140 and S150, the computer 10 sets a set of colorimetric data having the same gradation value of the image data at the time of printing among the colorimetric data of the reference patch, the first comparison patch, and the second comparison patch. Using the extracted colorimetric data, IDs (printer IDs) of the reference printer 20a, the first comparison printer, and the second comparison printer are generated. There are various ID generation methods for the reference printer 20a, the first comparison printer, and the second comparison printer. However, the color measurement data of the reference patch and the first comparison patch related to the common gradation value. The color measurement data and the color measurement data of the second comparison patch may be normalized based on a predetermined arithmetic expression, respectively, or only a specific component value among the Lab values of each color measurement data may be normalized. The result may be the printer ID.

  In this embodiment, as a simple method, a specific component value (from the color measurement data of the reference patch, the color measurement data of the first comparison patch, and the color measurement data of the second comparison patch related to the common gradation value is described. In the case of a C single color patch, for example, only the b component) is extracted, and the extracted component value itself is used as the printer ID. In the following, the printer ID of the generated reference printer 20a is called ID_st, the printer ID of the first comparison printer is called ID_1, and the printer ID of the second comparison printer is called ID_2. Further, the above-described common gradation values for the reference patch, the first comparison patch, and the second comparison patch to which the colorimetric data of the generation sources of ID_st, ID_1, and ID_2 are given are appropriately set to the common gradation value ncom. Is written.

  The computer 10 stores ID_st, ID_1, and ID_2 in the HD 14. Since each of these printer IDs is based on the color measurement result of the patch printed by the same type printer based on the common gradation value ncom, it is ideal that they match each other. However, as described above, since the first comparison printer and the second comparison printer are different from the reference printer 20a in the ink ejection capability, ID_st, ID_1, and ID_2 all have different values. In other words, each deviation of ID_1 and ID_2 with respect to ID_st represents a deviation from the reference machine of the color reproduction capability of each of the first comparison printer and the second comparison printer.

  In S160, the computer 10 compares the colorimetric data of the reference patch relating to the specific gradation value n0 and the colorimetric data of the plurality of first comparison patches, thereby comparing the reference patch relating to the gradation value n0. A gradation value correction rule necessary for causing the first comparison printer to print a patch that can obtain colorimetric data equivalent to the colorimetric data is obtained. Similarly, by comparing the colorimetric data of the reference patch relating to the gradation value n0 with the colorimetric data of the plurality of second comparison patches, it is equivalent to the colorimetric data of the reference patch relating to the gradation value n0. The gradation value correction rule necessary for printing the patch from which the colorimetric data is obtained by the second comparison printer is obtained.

  FIG. 5 schematically shows how to determine the correction rule in S160. That is, as shown in the figure, the color difference ΔE (color difference in the Lab color space) is measured between the color measurement data of the reference patch A relating to the gradation value n0 and the color measurement data of the plurality of first comparison patches B. At the same time, the gradation value (referred to as gradation value n1) applied to the first comparison patch B that gives the smallest color difference ΔE among the obtained color differences ΔE is associated with the gradation value n0. As a result, the relationship between the gradation value n0 and the gradation value n1 is a correction rule for the first comparison printer. Similarly, the color difference ΔE between the colorimetric data of the reference patch corresponding to the gradation value n0 and the colorimetric data of the plurality of second comparison patches is obtained, and the second comparison is used for minimizing the color difference ΔE. The gradation value applied to the patch (referred to as gradation value n2) is associated with the gradation value n0. As a result, the relationship between the gradation value n0 and the gradation value n2 is a correction rule for the second comparison printer.

  Note that the common gradation value ncom when the reference patch, the first comparison patch, and the second comparison patch from which ID_st, ID_1, and ID_2 are generated are printed, and the specific gradation value n0. May or may not match. However, when the gradation value n0 is the only common value among the gradation values at the time of printing of the reference patch, the first comparison patch, and the second comparison patch (when there is only one reference patch). The gradation value n0 also becomes the common gradation value ncom.

  In S170, the computer 10 refers to the correspondence relationship between each ID generated in S140 and S150 and the correction rule generated in S160, so that an arbitrary printer ID is used as an input value for the specific gradation value n0. A correction rule determining function F capable of determining the corrected tone value is obtained by calculation. The arbitrary printer ID referred to here is generated based on the colorimetric data of the plain patch based on the specific ink type printed by the printer of the same type as the reference printer 20a based on the common gradation value ncom. Say the printer ID.

FIG. 6 shows the correction rule determination function F.
In the figure, the printers for the reference printer 20a, the first comparison printer, and the second comparison printer are arranged on a plane in which the horizontal axis is the printer ID value and the vertical axis is the gradation value from 0 to 255. The coordinate points P0 to P2 are plotted by associating ID (ID_st, ID_1, ID_2) with the corrected gradation value for the specific gradation value n0. A straight line obtained by approximation by the least square method with reference to the positions of the coordinate points P0 to P2 is set as a correction rule determination function F.

  When the correction rule determination function F is obtained as described above, the computer 10 stores the function F in the HD 14 in S180. The correction rule determination function F can be obtained by various calculation methods such as spline interpolation using the coordinate points P0 to P2 as reference points in addition to the approximation by the least square method. In the above description, the number of comparison printers is two, but the number is not limited. That is, more comparison printers having a color reproduction capability that is different from the reference printer 20a are prepared, and the comparison patches are printed based on the comparison patch image data, and obtained based on the color measurement results. By referring to the correction rule relating to each printer ID and the gradation value n0, it is possible to more accurately obtain the corrected gradation value for the specific gradation value n0 using an arbitrary printer ID as an input value. The correction rule determination function F can be acquired.

  As described above, the correction rule determination function F shows the correspondence between an arbitrary printer ID and the correction rule for the specific gradation value n0. Image data in a printer having the same printer ID In the correction processing of the image data when printing is performed based on the above, a correction rule for each gradation value is required. Therefore, in the present embodiment, the computer 10 obtains a correction rule for each gradation value as follows.

  FIG. 7 shows a correction function that defines a correction rule for each gradation value (0 to 255 gradations) determined according to each printer ID. In the figure, correction functions f0 to f3 corresponding to the respective printer IDs are shown on a plane in which the horizontal axis is the gradation value before correction and the vertical axis is the gradation value after correction. For example, the correction function f3 is obtained as follows. When the computer 10 obtains a value of ID_3 as an arbitrary printer ID, the computer 10 inputs the ID_3 to the correction rule determination function F, thereby acquiring the corrected gradation value n3 for the uncorrected gradation value n0. Then, the point Q3 specified on the plane of FIG. 7 by the acquired corrected gradation value n3 and the uncorrected gradation value n0 and the origin 0 are connected by a straight line. As a result, the straight line becomes the correction function f3 corresponding to ID_3.

(3) Setting ID for Mass Production Printer After generating the correction rule determination function F as described above, the computer 10 performs a predetermined ID setting process for each mass production printer 20b.
8 and 9 are flowcharts showing an example of ID setting processing executed by the computer 10. This process is executed according to the color correction program.
In S200, the computer 10 selects one mass production printer 20b to be processed. The selection here refers to the case where one of the computers 10 is selected in a situation where the computer 10 is connected to a plurality of mass production printers 20b, or the operator sequentially connects the mass production printers 20b one by one. The process includes a case where the computer 10 recognizes the mass production printer 20b connected at that time.

  In S205, the computer 10 inputs the lot information of the selected mass production printer 20b. The lot information means a production lot of a predetermined part constituting the mass production printer 20b, and as an example, in the present embodiment, means a production lot of the print head 29 mounted on each mass production printer 20b. The lot information is information for distinguishing the predetermined parts that are mass-produced for each group having the same manufacturing conditions (for example, when assembled and manufactured at the same time based on materials purchased at the same time). is there.

  The lot information may be recorded in advance in a predetermined storage area provided in the mass production printer 20b, such as the memory 31 provided in the print head 29, or may be recognized by a worker at a predetermined location on the housing of the mass production printer 20b. May be recorded. When lot information is recorded in a predetermined storage area such as the memory 31, the computer 10 obtains the lot information by communication via the printer I / F 17d. On the other hand, when lot information is recorded at a predetermined location of the housing of the mass production printer 20b, the computer 10 can obtain the lot information in accordance with the lot information input operation by the operator.

  In S210, the computer 10 determines whether or not the input lot information is specific lot information. In other words, by determining whether the input lot information matches the specific lot information, the mass production printer 20b sharing the specific lot information is extracted from a large number of mass production printers 20b. If the determination is “No”, the computer 10 returns to the process of S200 and newly selects one mass production printer 20b.

  On the other hand, if “Yes” is determined in S210, the computer 10 sends a patch based on the specific ink type (ID generation patch) to the mass production printer 20b based on the image data for ID generation patch. Is printed on the printing paper (S215). The image data for ID generation patch is image data expressing gradation of ink recording amount for each ink type for each pixel, and the reference patch, the first comparison patch, the generation source of the ID_st, ID_1, and ID_2, This is image data representing a patch of only the specific ink type by the common gradation value ncom when the second comparison patch is printed.

  In this embodiment, when the mass production printer 20b performs printing based on the ID generation patch image data, the ID generation patch image data is shifted from the design standard of the ink amount of the dots ejected by the mass production printer 20b. Correct according to. In each mass production printer 20b, a head ID representing a deviation of the ink amount from the design standard is recorded in the memory 31 of the print head 29 in advance. The head ID is of a different type from the ID set for the mass production printer 20b in the ID setting process in FIGS. 8 and 9, and is obtained in advance as follows. That is, a dot of a predetermined size is ejected to the print head 29 mounted on the mass production printer 20b that is the target of setting the head ID, and the weight of the ejected dot is measured. Then, the measured weight is compared with the weight of the dot of the predetermined size discharged on the print head (print head mounted on the reference printer 20a) as a design standard, and the difference is normalized, for example. ID.

  In S215, the computer 10 acquires the head ID from the memory 31 of the print head 29 through communication with the mass production printer 20b, and corrects the image data for ID generation patch according to the acquired head ID value. Specifically, the computer 10 stores correction information corresponding to the size of each head ID that can take various values in advance in the HD 14, and an ID generation patch is obtained based on the correction information corresponding to the acquired head ID. The gradation value (gradation value ncom) of each pixel expressing a patch in the image data for correction is corrected. That is, when the head ID indicates that the ink amount of the dots ejected by the mass-production printer 20b is deviated from the reference, the gradation value is determined by correction information corresponding to the magnitude of the deviation. If the correction is made to reduce ncom and the head ID indicates that the ink amount of the dots ejected by the mass-production printer 20b is deviated from the reference, the magnitude of the deviation is large. Correction for increasing the gradation value ncom is performed by correction information corresponding to the above.

The correction information may be a correction coefficient that is uniquely determined according to the value of the head ID, or a gradation value before correction such as a γ curve and a value after correction that are determined according to the value of the head ID. It may be information defining a correspondence relationship with the gradation value.
In S220, the printed ID generation patch is measured by the colorimeter 40, and the computer 10 inputs the color measurement data of the ID generation patch obtained by the color measurement.

  In S225, the computer 10 predefines the processing for acquiring the color measurement data of the ID generation patch printed based on the image data for ID generation patch by the mass production printer 20b whose lot information is the specific lot information. It is determined whether or not the predetermined number (for example, several tens) has been completed. If the predetermined number has not been reached, the process returns to S200, and one new mass production printer 20b is selected, and the processes in S205 and subsequent steps are repeated. On the other hand, when the predetermined number is reached, the process proceeds to S230.

  In S230, the computer 10 generates a printer ID from the color measurement data of each ID generation patch printed on the predetermined number of mass production printers 20b by the same method as the processing in S140 and 150 of FIG. The average value of each printer ID is calculated. In this embodiment, the specific component value itself in the colorimetric data of each patch is used as a printer ID. Therefore, in S230, the specific component value is extracted from the colorimetric data for each patch for generating ID, and the average value for the plurality of extracted specific component values is calculated. Since the acquired average value is an average value of printer IDs of a plurality of mass production printers 20b having the same lot information, it is called a lot common printer ID (simply referred to as a lot ID). The lot ID corresponds to the representative color measurement result referred to in the claims.

  The ID generation patch printed on the mass production printer 20b based on the ID generation patch image data causes an error in the ink discharge amount of the print head 29 of the mass production printer 20b due to the effect of the correction of the image data using the head ID. The color is compensated for color misregistration. Therefore, the color measurement data of the ID generation patch has a value close to the color measurement data of the reference patch printed by the reference printer 20a in order to generate the ID_st. However, on the other hand, the factor affecting the color of the printed matter is not only the deviation of the ink amount of the dots ejected by the print head 29. For this reason, it is difficult to obtain an ideal color (a color output from the reference printer 20a) completely in the printing result only by correcting the image data according to the head ID.

  That is, the difference between the ID_st and the printer ID generated from the color measurement data of the ID generation patch printed on one mass production printer 20b is the dot discharged from the print head 29 in the one mass production printer 20b. It can be said that the degree of color misregistration of a printed matter due to a defect other than the ink amount deviation is expressed. If printing that corrects the color misregistration due to such a defect other than the ink amount deviation can be performed, the one mass production printer 20b. In this case, an extremely ideal color printing result can be obtained. Further, it can be said that the contents and extent of problems other than the deviation in the ink amount tend to be similar between the mass production printers 20b sharing the lot information. In other words, as the above problems, there may be a deviation from the ideal position of the dot landing position on the printing paper, a difference from the ideal shape of the dot shape when ejected on the printing paper, Such a defect appears in the same tendency if the mass production printer 20b has the same lot information (printing head manufacturing lot).

  That is, in the mass production printer 20b having the same lot information, it can be said that the correction amount of the image data necessary for eliminating the color misregistration due to the trouble other than the misregistration of the ink amount is almost the same. Therefore, in the present invention, the lot ID is obtained as one printer ID representing the printer ID of each of a plurality of mass production printers 20b having the same lot information. Such a deviation of the lot ID from the ID_st indicates the degree of color misregistration that each mass production printer 20b that owns the lot ID causes in the printing result due to a defect other than the deviation of the ink ejection amount of the print head 29. Show.

  Turning to the description of FIG. This figure shows processing for setting the calculated lot ID in each mass production printer 20b. In S235, the computer 10 selects one mass production printer 20b to be processed as in S200. The aircraft selected here includes the aircraft selected in S200. In S240, as in S205, the lot information of the selected mass production printer 20b is input. In S245, as in S210, it is determined whether the input lot information is the specific lot information.

If “Yes” is determined in S245, the computer 10 sets the lot ID calculated in S230 for the mass production printer 20b selected in S235 (S250). That is, the computer 10 copies the lot ID calculated in S230 and records it in the memory 31 of the mass production printer 20b.
In S255, the computer 10 determines whether the lot ID has been set for all the mass production printers 20b sharing the specific lot information (for example, several hundreds), and there is an unset number. In this case, the process returns to S235 and a new mass production printer 20b is selected. On the other hand, when it is determined that the lot ID has been set for all the mass production printers 20b sharing the specific lot information, the flowchart is ended.

As described above, in the present embodiment, based on the color measurement results of the ID generation patches printed on some of the mass production printers 20b among the mass production printers 20b grouped into one group based on the specific lot information, One lot common printer ID is generated, and the generated lot ID is set to all mass production printers 20b belonging to the group.
In the above description, the specific meaning of the lot information of the mass production printer 20b is the production lot of the print head 29, but the meaning of the lot information is not limited to this. In other words, there are factors other than the lot difference of the print head 29 that affect the color of the print product. For example, the color of the print product is also affected by the uneven speed of the reciprocating movement of the print head 29 and the paper feed accuracy of the print paper. It can change. Therefore, a production lot for the carriage mechanism 27a that realizes the reciprocation of the print head 29 and the paper feed mechanism 27b that controls the paper feed of the printing paper may be handled as the lot information.

(4) Print Control Processing Next, the processing in which the computer 10 controls the mass production printer 20b in which the lot ID is set as described above to execute printing will be described focusing on image data correction processing.
FIG. 10 is a flowchart showing the contents of print control processing executed by the computer 10. This process is executed in a state where the computer 10 and the mass production printer 20b are connected.

  First, in S300, the computer 10 acquires a head ID and a lot ID from the mass production printer 20b. Specifically, the computer 10 creates an acquisition request for the head ID and the lot ID and transmits the request to the mass production printer 20b. Then, the mass production printer 20b receives the acquisition request, reads the head ID and the lot ID from the memory 31 of the print head 29, and transmits them to the computer 10. The computer 10 acquires the head ID and lot ID and stores them in the HD 14. As described above, since the head ID and the lot ID are integrated with the mass production printer 20b, the user does not need to separately input an ID corresponding to the printer even if the mass production printer 20b to be used is changed.

  In S <b> 305, the computer 10 inputs image data representing an image to be printed from a predetermined image input device, the HD 14, or the like. The image data is data representing an image with gradation data for each of a plurality of pixels, and is image data composed of RGB defined in the sRGB color space or image data composed of YUV in the YUV color system. Etc. Of course, data conforming to the Exif 2.2 standard (Exif is a registered trademark of the Japan Electronics and Information Technology Industries Association), data corresponding to Print Image Matching (PIM: PIM is a registered trademark of Seiko Epson Corporation), or the like may be used. Since each component of the image data has various gradation numbers, the image data is converted into RGB data in which each RGB value of each pixel is expressed in 256 gradations in accordance with definitions such as sRGB and YUV color system.

In S310, the computer 10 reads the color conversion LUT 14a from the HD 14, and refers to the color conversion LUT 14a to express the RGB data as a gradation expression (256 gradations) for each CMYK ink type for each pixel. ) To be image data (CMYK data).
FIG. 11 simply shows the structure of the color conversion LUT 14a. As shown in the figure, the color conversion LUT 14a is an information table that defines a substantially equal color correspondence between RGB values and CMYK values for N reference points (RGB values). Therefore, when the reference point that matches the RGB value of one pixel that is the target of color conversion is defined in the color conversion LUT 14a, the computer 10 determines the CMYK value corresponding to the matching reference point from the color conversion LUT 14a. The pixel value after the read color conversion is used. On the other hand, when a reference point that matches the RGB value of one pixel that is the target of color conversion is not defined in the color conversion LUT 14a, interpolation is performed using each CMYK value corresponding to a plurality of reference points close to the RGB value. A CMYK value for one pixel is calculated by calculation or the like, and this calculation result is used as a pixel value after color conversion. Such color conversion is performed for all the pixels constituting the image data.

In S315, the computer 10 corrects the image data (CMYK data) obtained as a result of the color conversion according to the head ID of the mass production printer 20b acquired in S300. That is, the computer 10 acquires correction information corresponding to the head ID from the HD 14 and corrects the gradation value (CMYK value) of each pixel constituting the CMYK data by using the correction information. This corrected image data is expressed as C′M′Y′K ′ data for convenience.
Here, if the mass production printer 20b performs printing based on the C′M′Y′K ′ data, it is considerably different from the color obtained when the reference printer 20a performs printing based on the CMYK data before correction. A printed matter with a close color can be obtained. However, as described above, in addition to the ink discharge amount deviation in the print head 29, there are other factors in the mass production printer 20b that cause color misregistration in the printed matter. Such factors differ between the mass production printers 20b having different lot information. ing.

  Therefore, in S320, the computer 10 corrects the C′M′Y′K ′ data according to the lot ID of the mass production printer 20b acquired in S300. That is, the computer 10 inputs the lot ID to the correction rule determination function F, and acquires the corrected gradation value (the gradation value n4) for the gradation value n0 corresponding to the lot ID. Next, similarly to the generation of each correction function shown in FIG. 7, the coordinate point specified by the pre-correction gradation value n0 and the post-correction gradation value n4 is the post-correction gradation value with the pre-correction gradation value as the horizontal axis. A gradation value is plotted on a plane having a vertical axis, and a straight line obtained by connecting the plotted coordinate point and the origin 0 is used as a correction function. And the gradation value of each pixel which comprises C'M'Y'K 'data is each corrected by the correction function acquired in this way. This corrected image data is expressed as C "M" Y "K" data for convenience.

  Next, in S325, the computer 10 refers to the dot allocation table 14b to obtain the gradation value for each ink type in each pixel of the C "M" Y "K" data for a plurality of different ink amounts. A dot distribution process for converting the gradation value for each dot type representing the ink recording amount for each dot type is executed.

FIG. 12 simply shows the structure of the dot distribution table 14b in the upper part.
The dot distribution table 14b includes an input gradation value representing an ink recording amount for each ink type used in the mass production printer 20b, and a dot type (in this embodiment, three types of large dots, medium dots, and small dots). ) Is an information table that defines the correspondence with the output gradation value representing the ink recording amount for each. In the table 14b, output tone values for each dot type are stored in correspondence with each tone of the input tone value. Therefore, the computer 10 refers to the dot distribution table 14b and distributes the gradation values for each CMYK in each pixel of the C "M" Y "K" data to the gradation values for each of the small, medium, and large dots. , An output tone value si for small dots, an output tone value mi for medium dots, and an output tone value li for large dots, respectively. As a result, in each pixel, image data expressing the ink recording amount for each ink type and each dot type in gradation is generated.

  In S330, the computer 10 performs predetermined halftone processing such as an error diffusion method, a dither method, and a density pattern method on the image data for each ink type and each dot type after the above-described dot distribution processing, and the CMYK data Data having the same number of pixels as the number of pixels, and halftone data that defines one of four states, large dots, medium dots, small dots, and no dots for each ink type, are generated for each pixel. In S335, the computer 10 performs a predetermined rasterizing process on the generated halftone data and rearranges the generated halftone data in the order used by the mass production printer 20b to generate raster data for each CMYK. In S340, the mass production printer 20b. In response to this, the raster data is output and the flowchart is terminated. Then, the mass production printer 20b obtains the raster data, drives the print head 29 based on the raster data, ejects ink to adhere to the print paper, and print image corresponding to the image data acquired in S305. Form.

  As described above, according to the present invention, when the computer 10 prints an arbitrary image on a certain mass production printer 20b, the head ID possessed by the mass production printer 20b is targeted for the image data defining the recording amount for each ink type. Further, correction is performed according to a correction rule (correction function) for each gradation value generated based on the lot ID owned by the same mass production printer 20b and the correction rule determination function F. As a result, a mass production printer 20b having a different color lot from the printing result by the reference printer 20a, which is slightly generated even when printing is performed after correction according to the head ID, is performed. The color misregistration that appears with a different tendency every time is surely corrected, and a printed matter having an extremely close color can be output by each mass production printer 20b.

  In the above description, the correction target corresponding to the lot ID is the image data after the color conversion process and before the dot distribution process. However, the correction may be performed for other timing or other data in the print control process. . As an example, the computer 10 corrects the output gradation value for each dot type output as a result of distribution by the dot distribution table 14b. In this case, the computer 10 skips the process of S320 after S315. In step S325, a dot distribution process is executed by the dot distribution table 14b for the C′M′Y′K ′ data. Then, the output gradation value si for small dots, the output gradation value mi for medium dots, and the output gradation value li for large dots, which are output as a result of the dot distribution process for each ink type, are targeted. Then, correction is performed in accordance with the correction function acquired based on the lot ID obtained from the mass production printer 20b and the correction rule determination function F. Also by this method, the mass production printer 20b corrects both the color misregistration caused by the deviation from the reference of the ink discharge amount of the print head 29 and the color misregistration specific to the lot information that it has, and is ideal. Printed material with the correct color is output.

  As shown in the lower part of FIG. 12, according to the correction function acquired based on the lot ID obtained from the mass production printer 20b and the correction rule determination function F, the small dot stored in the dot distribution table 14b is stored. The output tone value si, the medium tone output tone value mi, and the large dot output tone value li itself may be corrected. In other words, the output gradation value si ′ for small dots, the output gradation value mi ′ for medium dots, and the output gradation value li ′ for large dots obtained by correction according to the correction function are used as the dot distribution table 14b. And the table 14b may be reconstructed.

  When correcting the output tone value for each dot type according to the lot ID, only the output tone value for a specific dot type is used instead of correcting the output tone value for all small, medium and large dots. It may be corrected. For example, only the output tone value si for small dots is corrected. When printing an image by ejecting ink, there is an upper limit (ink duty) of the total amount of ink ejected per predetermined area of the printing paper, and the above-mentioned upper limit is set so that the amount of ink actually ejected does not exceed the upper limit. The dot distribution table 14b defines output tone values for each dot type. Here, when the output tone value for each of the small, medium, and large dots of each ink type is corrected, depending on the degree of correction, the amount of ejected ink exceeds the ink duty, and as a result, the image quality is degraded. there is a possibility. In particular, when a large dot or medium dot tone value that has a large influence on image quality by one dot is corrected, such a possibility increases.

  Therefore, as described above, as an example, the correction target corresponding to the lot ID is only the small dot output tone value si among the output tone values for each of the small, medium, and large dots. As a result, it is possible to prevent image quality degradation that may occur when the output tone value si for small dots, the output tone value mi for medium dots, and the output tone value li for large dots are corrected. However, in this case, some changes are necessary for the generation method of the correction rule determination function F and the generation method of the lot ID. That is, in S100 and 120 of FIG. 4, the reference printer 20a and the reference patch to be printed by each comparison printer are printed by ejecting only small dots, respectively, and the mass production printer 20b is printed in S215 of FIG. The ID generation patch to be printed is printed by ejecting only small dots. As a result, the correction function determined based on the lot ID and the correction rule determination function F corrects the print result obtained by causing the reference printer 20b to eject small dots and the image data corresponding to the head ID. Thus, the color deviation from the printing result obtained by discharging the small dots to the mass production printer 20b is corrected over the entire gradation range. The computer 10 corrects the output gradation value si for small dots obtained by the dot distribution process using the correction function thus obtained.

(5) Change of reference printer So far, the color correction processing for making the color reproducibility by the mass production printer 20b equivalent to the color reproducibility by the reference printer 20a has been described. The reference printer 20a, which is a design reference machine for the mass production printer 20b, is basically a machine having color reproducibility ideal for the manufacturer of the mass production printer 20b. However, depending on the user, the color reproducibility by the reference printer 20a is not necessarily ideal. Therefore, in the following, a case will be described in which the printer used as a reference for color correction is changed according to the user's preference, and the color reproducibility by the change destination printer is realized in another printer.

FIG. 13 is a flowchart showing the contents of the reference printer changing process executed by the computer 10. The reference printer changing process is a process for newly creating a correction rule determining function.
First, in S400, in a state where a printer (new reference printer) newly selected as a reference machine for color correction by the user is connected to the computer 10, the computer 10 sends the reference patch image data to the new reference printer. Based on the above, a process of printing a patch (referred to as a new reference patch) on printing paper is performed. As a result, a new reference patch including at least a patch based on the specific ink type corresponding to the specific gradation value n0 is printed.

The new reference printer here is assumed to be one of mass-produced printers 20b having the same type as the reference printer 20a. That is, when the user has a plurality of mass production printers 20b, one of the mass production printers 20b is selected as a new reference printer, and a new reference patch is printed.
In S410, the new reference patch printed on the printing paper is color-measured by the colorimeter 40, and the computer 10 inputs the colorimetric data (Lab value) obtained by the colorimetry from the colorimeter 40. Since the new reference printer 20a is a machine newly selected as a reference machine for color correction, the color measurement data of the new reference patch becomes a reference color for subsequent color correction.

  In S420, the computer 10 generates the printer ID of the new reference printer using the color measurement data of the new reference patch related to the common gradation value ncom among the color measurement data of the new reference patch. That is, similar to the processing described in S140 and S150 of FIG. 4, only specific component values are extracted from the calorimetric data of the new reference patch related to the common gradation value ncom, and this component value itself is used as the printer ID. And Hereinafter, the printer ID of the new reference printer is referred to as ID_nst.

  In S430, the computer 10 calculates the color difference ΔE by comparing the calorimetric data of the new reference patch related to the specific gradation value n0 with the calorimetric data of the plurality of first comparison patches. The gradation value (referred to as gradation value n5) applied to the first comparison patch that gives the smallest color difference ΔE among the color differences ΔE is associated with the gradation value n0. Similarly, the color difference ΔE is calculated by comparing the color measurement data of the new reference patch related to the specific gradation value n0 with the color measurement data of the plurality of second comparison patches, and each color difference ΔE is calculated. Among these, the gradation value (referred to as gradation value n6) applied to the second comparison patch that gives the minimum color difference ΔE is associated with the gradation value n0.

  That is, when the new reference printer is a color correction reference machine, the relationship between the gradation value n0 and the gradation value n5 is the correction rule for the first comparison printer, and the gradation value n0 and the gradation value are the same. The relationship with n6 is a correction rule for the second comparison printer. Since the color measurement data of the plurality of first comparison patches and the color measurement data of the plurality of second comparison patches are already stored in the HD 14 as described above, the computer 10 stores the stored color measurement data. Use the data that is present.

  In S440, the computer 10 inputs an arbitrary printer ID by referring to the correspondence relationship between the ID_nst generated in S420, ID_1 and ID_2 already generated and stored in the HD 14, and the correction rule generated in S430. As a value, a correction rule determination function F ′ capable of determining a corrected gradation value for the specific gradation value n0 is obtained by calculation.

FIG. 14 shows how the correction rule determination function F ′ is generated. That is, basically as in the case where the correction rule determination function F is generated, the new reference printer and the first comparison printer are arranged on a plane having the horizontal axis as the printer ID value and the vertical axis as the gradation value. , Plotting the coordinate points specified by the correspondence between each printer ID (ID_nst, ID_1, ID_2) for the second comparison printer and the corrected gradation value for the specific gradation value n0. A straight line obtained by approximation by the least square method with reference to the position of the coordinate point is set as a correction rule determination function F ′.
When the correction rule determining function F ′ is obtained as described above, the computer 10 stores the function F ′ in the HD 14 in S450.
As described above, the correction rule determination function F ′ when the new reference printer is used as the reference machine for color correction is generated.

  Thereafter, when the computer 10 performs print control processing for an arbitrary mass production printer 20b, the computer 10 obtains a head ID and a lot ID possessed by the arbitrary mass production printer 20b, and expresses an arbitrary image. The data (CMYK data) is corrected according to the head ID and corrected according to the lot ID. Of course, the correction according to the lot ID in this case is that the lot ID is input to the correction rule determination function F ′ and the gradation value after correction for the gradation value n0 (referred to as gradation value n7). The coordinate point specified by the pre-correction gradation value n0 and the post-correction gradation value n7 is plotted on a plane with the pre-correction gradation value as the horizontal axis and the corrected gradation value as the vertical axis, The correction is performed using a correction function obtained by connecting the plotted coordinate points and the origin 0.

  As described above, when printing is performed by an arbitrary mass production printer 20b, the image data is corrected using the lot ID possessed by the arbitrary mass production printer 20b and the newly generated correction rule determining function F ′. As a result, in the printing result of the same mass production printer 20b, the same color as the printing result of the new reference printer is reproduced. That is, according to the present invention, when the user has a plurality of mass production printers 20b, the correction rule determination function F ′ can be generated by using one of the mass production printers 20b as a new reference printer. In the other mass production printer 20b having the ID, the color reproducibility can be matched with the color reproducibility of the new reference printer by using the lot ID and the correction rule determination function F ′.

The block diagram which shows a computer and a printer. The figure which expands and shows a nozzle and its internal structure. The figure which shows an example of the system suitable for implementation | achievement of this invention. The flowchart which showed the content of the production | generation process of a correction rule determination function. The figure which showed roughly a mode that a correction rule was calculated | required. The figure which showed the correction rule determination function. The figure which showed the correction function according to each printer ID. The flowchart which showed a part of content of ID setting process. The flowchart which showed a part of content of ID setting process. The flowchart which showed the content of the printing control process. The figure which showed the data structure of the color conversion LUT. The figure which showed the data structure of the dot allocation table. 6 is a flowchart showing the contents of a reference printer change process. The figure which showed the other correction rule determination function.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Computer, 11 ... CPU, 12 ... ROM, 13 ... RAM, 14 ... Hard disk (HD), 14a ... Color conversion LUT, 14b ... Dot allocation table, 20 ... Printer, 20a ... Standard printer, 20b ... Mass production printer, 29 ... print head, 31 ... non-volatile semiconductor memory, 40 ... colorimeter

Claims (9)

A color correction device that corrects color misregistration in a print image that is printed based on predetermined gradation data in a printing device including a print head that discharges dots,
Acquires color measurement results of patches printed on multiple printing devices based on common gradation data, and calculates representative color measurement results representing each color measurement result based on each color measurement result Calculating means for
In accordance with the value of the representative colorimetry result, a gradation data correction rule for correcting color misregistration between a printing result by the plurality of printing devices and a printing result by a desired reference printing device as a color correction reference is set. A correction rule determining means for determining;
Printing control means for correcting gradation data representing an arbitrary image using the determined correction rule and causing the printing apparatus that has printed the patch to print based on the corrected gradation data; A color correction device characterized by the above.   The calculation unit acquires and acquires a deviation between a dot ink amount ejected by a print head included in each printing device and a design reference amount of the dot ink amount when each of the plurality of printing devices prints a patch. The color correction apparatus according to claim 1, wherein the common gradation data is corrected according to each of the deviations, and printing is performed based on the corrected gradation data.   3. The representative color measurement result according to claim 1, wherein the calculation means calculates a representative color measurement result based on a color measurement result of a patch printed on a plurality of printing apparatuses having a common manufacturing lot of a predetermined part. The color correction apparatus according to any one of the above.   The color correction apparatus according to claim 3, wherein the calculation unit causes a plurality of printing apparatuses having a common print head manufacturing lot to print a patch.   The said calculation means averages the colorimetry result of the patch printed on said several printing apparatus, This average value is made into a representative colorimetry result, The claim 1 characterized by the above-mentioned. Color correction device.   The reference printing device includes the specific gradation data in the color measurement result of the reference patch that is printed based on the specific gradation data, and the comparison printing device that causes a color shift in the printing result by the reference printing device. Correction rules for gradation data acquired from the result of comparison with the colorimetric results of a plurality of comparison patches printed based on gradation data of multiple stages, and the reference printing device and comparison based on the common gradation data A correction rule determining function capable of determining a correction rule according to a value of an arbitrary representative color measurement result based on the color measurement result of each patch printed on the printer for printing. 6. The color correction apparatus according to claim 1, wherein the correction rule is determined by referring to the rule determination function.   The print control means, when converting the gradation data expressing the arbitrary image into dot type gradation data expressing the recording amount for each of a plurality of dot types having different ink amounts per droplet, The color correction apparatus according to claim 1, wherein the correction is performed only for the dot type gradation data relating to a specific dot type among the dot types. A color correction method for correcting a color misregistration in a print image to be printed based on predetermined gradation data in a printing apparatus including a print head that discharges dots,
Acquires color measurement results of patches printed on multiple printing devices based on common gradation data, and calculates representative color measurement results representing each color measurement result based on each color measurement result A calculation step to perform,
In accordance with the value of the representative colorimetry result, a gradation data correction rule for correcting color misregistration between a printing result by the plurality of printing devices and a printing result by a desired reference printing device as a color correction reference is set. A correction rule determination step to be determined;
A printing control step of correcting gradation data representing an arbitrary image using the determined correction rule, and causing the printing apparatus that has printed the patch to print based on the corrected gradation data. A color correction method characterized by the above. A color correction program for causing a computer to execute a process of correcting color misregistration in a print image to be printed based on predetermined gradation data in a printing apparatus including a print head that discharges dots,
Acquires color measurement results of patches printed on multiple printing devices based on common gradation data, and calculates representative color measurement results representing each color measurement result based on each color measurement result A calculation function to
In accordance with the value of the representative colorimetry result, a gradation data correction rule for correcting color misregistration between a printing result by the plurality of printing devices and a printing result by a desired reference printing device as a color correction reference is set. A correction rule determination function to be determined;
Using the determined correction rule, the gradation data representing an arbitrary image is corrected, and a printing control function for causing the printing apparatus that has printed the patch to print based on the corrected gradation data is executed. A color correction program characterized by that.

Images