JP2008072602A - Color adjustment on printing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve efficiency of calibration and color matching. <P>SOLUTION: A calibration means performs calibration for obtaining a color reproduced by a printer in a predetermined standard color. After the calibration, a color matching means performs color matching so that the color reproduced by the printer agrees with the desired target color. Namely, as a condition for color matching, the calibration is required. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to color adjustment for a printing apparatus.

Printer calibration is performed to compensate for differences in color reproducibility between printer bodies. Specifically, calibration is performed by adjusting the output characteristics of the ink so that the reproduced color of the calibration target machine approaches the reproduced color of the standard machine (for example, see Patent Document 1). At that time, a patch of a plurality of colors is printed, the amount of deviation of the colorimetric value of the patch from the target reproduction color of the standard machine is grasped, and the ink output characteristics are corrected so as to compensate for the amount of deviation. By performing such calibration, it is possible to match the reproduction color of the calibration target machine with the reproduction color of the standard machine.
On the other hand, color matching of a printer is performed by adjusting an ICC profile or the like so that a color reproduced by the printer matches a desired target color (see, for example, Patent Document 2). Also in color matching, a patch of a plurality of colors is printed, a deviation amount of the colorimetric value of the patch with respect to the target color is grasped, and an output characteristic of the ink is corrected by an ICC profile or the like so as to compensate for the deviation amount. For example, if the reproduction color of the printer is matched with the reproduction color of the screen printing machine as a target, the result of the color when output by the screen printing machine can be confirmed in advance by printing with the printer.
JP 2005-204053 A JP 2003-298862 A

Although both the printer calibration and the color matching described above have similar properties in that the reproduced color of the printer can be adjusted, there has been no method for comprehensive management so that these can be performed efficiently. For example, even when an ICC profile is created in which a desired target color can be reproduced by the printer by performing color matching with a certain printer, the other color is reproduced by the other printer in order to reproduce the target color. It is necessary to perform color matching again on the printer and create an ICC profile for the other printer. This is because even if the model is the same, there are variations in the reproduced color for each printer body. Also, even when an ICC profile is created in which a desired target color can be reproduced by the printer by performing color matching on a certain printer, if the reproduction color of the printer changes over time, It is necessary to recreate the ICC profile by performing color matching again with the printer. That is, color matching has to be performed each time there is a change in the reproduced color on the same machine or a change in the reproduced color between a plurality of machines. Since color matching generally requires that high-dimensional color spaces be associated with each other, there is a problem that processing that requires a large burden must be performed each time the reproduced color of the printer fluctuates.
The present invention has been made in view of the above-described problems, and an object thereof is to efficiently perform printer calibration and color matching.

  In order to achieve such an object, according to the first aspect of the present invention, first, the calibration unit performs calibration for matching the color reproduced by the printing apparatus with a predetermined standard color. Here, the standard color may be a predetermined color, and the color reproduced by the standard machine of the printing apparatus is generally used as the standard color. By performing calibration with a plurality of printing apparatuses, it is possible to compensate for variations in reproduced colors among the printing apparatuses. In addition, by performing calibration at a plurality of times with the same printing apparatus, it is possible to compensate for variations in reproduced colors over time in the same printing apparatus.

  The color matching means performs color matching that matches the color reproduced by the printing apparatus with a desired target color on the condition that calibration has been performed. That is, it is necessary to perform calibration as a condition for performing color matching. Since the color matching is performed after the variation in the reproduction color of the printing apparatus is compensated in advance, the color matching itself can be prevented from receiving the variation in the reproduction color. Therefore, the effect of color matching does not extend only to a specific machine body at a specific time, but extends to any printing apparatus calibrated in advance to the same standard color. Therefore, for example, an ICC profile created by performing color matching can be effectively used in another calibrated printing apparatus, and color matching does not have to be performed in another printing apparatus.

  Both the calibration means and the color matching means adjust the reproduction color on the recording medium by adjusting a profile that defines the amount of ink that the printing apparatus discharges to the recording medium. That is, the printing apparatus of the present invention forms an image corresponding to image data on a recording medium by ejecting ink onto the recording medium. For this reason, the calibration unit and the color matching unit can adjust the reproduced color on the recording medium by adjusting the profile that defines the amount of ink ejected by the printing apparatus onto the recording medium. As a desirable configuration, if the profiles adjusted by the calibration means and the color matching means are independent from each other, the profiles adjusted by the color matching means can be handled independently. Therefore, the profile can be duplicated so that it can be used in another calibrated printing apparatus, and color matching in the other printing apparatus can be omitted.

  According to a second aspect of the present invention, the color matching unit prints a plurality of color patches covering the entire color space by the printing apparatus. Then, based on the color measurement results of these patches, the first ink amount profile that defines the spatial correspondence between the predetermined color space and the ink amount space is adjusted. The change in color due to the color mixture of a plurality of inks has a non-linear element and also affects the interaction caused by the color mixture of the plurality of inks. It is necessary to prescribe in. According to the first ink amount profile, an image can be formed by generating an ink amount corresponding to arbitrary image data whose color is specified in a predetermined color space. Since the amount of ink generated at that time can be adjusted, the color matching means can adjust the reproduced color of the printing apparatus. Since colors of patches of a plurality of colors covering the entire color space are measured, it is possible to grasp a color tendency when a plurality of inks are mixed in various composition ratios, and a guideline for adjusting the first ink amount profile is provided. Obtainable.

  On the other hand, the calibration unit also adjusts the profile based on the color measurement result of the color reproduced by the printing apparatus. The second ink amount profile adjusted here is a correction amount for each ink amount of each ink. The profile is defined. That is, the second ink amount profile is a profile that defines how much ink amount should be increased or decreased as a correction amount when a certain ink amount of a certain ink is input. For example, if the standard color has a linear output characteristic, the calibration is performed so that the second ink amount profile defines a correction amount that can realize a linear output characteristic with respect to the input value of the ink amount. Adjustment means. Here, in order to obtain a colorimetric result by printing a plurality of color patches in which the ink amount of each ink is changed independently, and to obtain the color measurement result, an appropriate correction amount is set for each ink amount of each ink. Obtainable. In addition, since each ink amount is handled independently, calibration is realized by processing with less burden than color matching that requires adjustment of the correspondence between high-dimensional color spaces.

  In this way, the processing load is greatly different between calibration and color matching, and the overall processing is performed by first performing color matching on the condition that calibration with a low processing load is performed. Efficiency can be improved. In other words, it is possible to prevent color matching with a heavy processing load from being performed unnecessarily and impairing efficiency by using calibration as a condition.

  Furthermore, the invention described in claim 3 assumes a case where adjustment data adjusted by the color matching means is created by performing the calibration and the color matching in a printing apparatus. In this case, normally, in order to reproduce the target color in another printing apparatus, it is necessary to perform the color matching in another printing apparatus, but the calibration is performed in the other printing apparatus. The adjustment data can be used also in the other printing apparatus. That is, if the above calibration is executed in both printing apparatuses, the variation in color reproducibility between the two should be compensated, and the color matching performed in one printing apparatus on the other is It can be considered that the printing apparatus is similarly effective. Therefore, by making the adjustment data created by color matching usable in both printing apparatuses, it is possible to accurately reproduce the target color without performing color matching in both printing apparatuses.

  Further, even when adjustment data of the first ink amount profile is created by performing the calibration and the color matching in a certain printing apparatus, the color reproduction of the same printing apparatus due to factors over time or the like It is also possible that the sex has fluctuated. In that case, since the adjustment data that has been once created effectively also lacks accuracy, in the invention according to claim 4, the adjustment data can be used on condition that calibration is performed again. . That is, if the calibration is executed both immediately before the color matching in the past and at the present time, variations in color reproducibility between the past and the current should be compensated. It can be considered that the adjustment data effectively created in the color matching performed is also effective in the current printing apparatus. Therefore, it is possible to accurately reproduce the target color without performing color matching again.

  Of course, the above invention can be realized not only by the apparatus but also by the color adjustment method as in claim 5, and by a color adjustment program for executing processing according to the method as in claim 6. It can also be realized. In addition, the apparatus, method, and program according to the present invention may be executed independently, and, for example, other apparatuses, methods, and programs are incorporated in a device such as the print control system according to claims 7 to 9. The idea of the invention is not limited to this, such as being implemented together with a program, and includes various aspects and can be changed as appropriate. Since the seventh to ninth aspects also have special technical features for performing color matching on the condition that calibration has been performed, similar effects can be obtained. For example, the effect of the present invention can be similarly obtained in a color matching apparatus that determines whether or not color matching can be performed depending on whether calibration is performed in advance. Similarly, the effects of the present invention can be similarly obtained in a calibration apparatus or the like in which the availability of adjustment data is determined on the condition that calibration has been performed.

  Further, it can be provided as a recording medium on which the program of the present invention is recorded. The recording medium for this program may be a magnetic recording medium, a magneto-optical recording medium, or any recording medium that will be developed in the future. In addition, the duplication stages such as the primary duplication product and the secondary duplication product are equivalent without any question. Further, even when a part is software and a part is realized by hardware, the idea of the invention is not completely different, and a part is stored on a recording medium and is appropriately changed as necessary. It may be in the form of being read. In addition, not all functions are necessarily realized by a single program, but may be realized by a plurality of programs. In this case, what is necessary is just to make each function implement | achieve in a some computer.

Here, embodiments of the present invention will be described in the following order.
(1) Color adjustment system:
(2) Various management processes:
(3) About calibration:
(4) About color matching:

(1) Color Adjustment System FIG. 1 shows a schematic configuration of a color adjustment system and a print control system according to an embodiment of the present invention. Note that the color adjustment system and the print control system of the present invention need only be able to perform color adjustment for the printing apparatus, and need not include the printing apparatus as a component. In the figure, the color adjustment system 100 is composed of a computer 10 and a server 70 that are connected to each other via the Internet INT so as to communicate with each other. A standard printer 71 and a colorimeter 72 are connected to the server 70. Based on the patch data B15a2, the standard printer 71 prints a calibration color patch in advance, and the colorimetric value of this color patch is acquired by the colorimeter 72. The colorimetric values are stored as standard color data 73 represented by CIELAB values (L ^* a ^* b ^* values) and XYZ values, for example, and can be transmitted to the computer 10. A printer 40 is connected to the computer 10, and a digital screen printer 60 capable of executing printing based on image data output from the computer 10 via a recording medium or a LAN is provided. The digital screen printer 60 performs a large amount of printing with a plate created according to the image data 15a to be printed.

  FIG. 2 is a block diagram showing a schematic configuration of the computer 10 and its peripheral devices. The computer 10 includes a CPU (not shown) serving as the center of arithmetic processing, a ROM, a RAM, and the like as a storage medium, and can execute a predetermined program using peripheral devices such as the HDD 15. An operation input device such as a keyboard 31 and a mouse 32 is connected to the computer 10 via a serial communication I / O 19a, and a display 18 is also connected via a video board (not shown). Further, it is connected to the printer 40 via a USB I / O 19b.

  In addition, the colorimeter 50 is connected via the USB I / O 19b. The printer 40 according to the present embodiment includes a mechanism in which an ink cartridge that fills a plurality of colors of ink is detachable for each color, and each ink of CMYKlclm (cyan, magenta, yellow, black, light cyan, light magenta) is included in this mechanism. Mount the cartridge. The printer 40 can form a large number of colors by combining these ink colors, thereby forming a color image on the print medium. In this embodiment, the printer 40 can eject ink droplets with three different ink amounts, and can express four gradations for one pixel. In this specification, paying attention to the size of ink droplets, each ink droplet is called a large, medium, and small dot. The printer 40 in the present embodiment is an ink jet printer, but the present invention can be applied to various printers such as a laser method in addition to the ink jet method.

Furthermore, a configuration using six colored inks of CMYKlclm is not essential, and a configuration using four colors of CMYK or seven colors of CMYKlclmDY (dark yellow) may be used. Of course, other colors such as R (red) and V (violet) may be used instead of the lclm ink, and a dark and light ink may be used for the K ink. In the colorimeter 50, the printed material is irradiated with a known light source and the reflected light is detected to detect the spectral reflectance of the printed material, and its color value, for example, CIELAB value (L ^* a ^* b ^* value) or XYZ. A value can be output.

  In this embodiment, the CIELAB value of the patch printed by the printer 40 is measured and output as colorimetric data to the USB I / O 19b. Further, the connection interface between the computer 10 and the printer 40 and the connection interface between the computer 10 and the colorimeter 50 need not be limited to those described above, and various connection modes such as a parallel interface, SCSI connection, and wireless connection can be adopted. The same applies to any connection mode to be developed in the future.

  In the computer 10, a printer driver (PRTDRV) 21, an input device driver (DRV) 22, and a display driver (DRV) 23 are incorporated in the OS 20. The display DRV 23 is a driver that controls display of images, printer property screens, and the like on the display 18, and the input device DRV 22 receives code signals from the keyboard 31 and mouse 32 input via the serial communication I / O 19 a. Thus, the driver receives a predetermined input operation.

  The PRTDRV 21 can execute printing by performing predetermined processing on an image for which a print instruction has been issued from an application program (not shown) or a patch image described later. The PRTDRV 21 includes an image data acquisition module 21a, a color conversion module 21b, a large / medium / small dot generation module 21c, a halftone processing module 21d, and a print data generation module 21e in order to execute printing. When the above-described printing instruction is given, the PRTDRV 21 is driven, and the PRTDRV 21 sends data to the display DRV 23 to give information indicating printing conditions such as a printing medium, image quality, and printing speed, and an instruction for executing a calibration operation. A UI (not shown) to be input is displayed.

  When the user inputs information necessary for printing through the UI by operating the keyboard 31, mouse 32, etc., and issues a print execution instruction, each module of the PRTDRV 21 is activated. Processing is performed on each pixel data of the image data, and print data is generated. The generated print data is output to the printer 40 via the USB I / O 19b, and the printer 40 executes printing based on the print data.

  More specifically, the image data acquisition module 21a acquires image data 15a indicating an image to be printed. At this time, if there is an excess or deficiency in the number of pixels of the image data 15a, resolution conversion processing is performed as appropriate in order to secure the pixels necessary for printing. This image data 15a is dot matrix data in which each color component of RGB (red, green, blue) is expressed in gradation to define the color of each pixel. In the present embodiment, each color has 256 gradations, and the sRGB standard. The image data adopts a color system according to the above. Two types of patch data A15a1 and patch data B15a2 for printing color patches are prepared as part of the image data 15a. The standard printer 71 and the printer 40 print a calibration patch based on the patch data A15a1, and the digital screen printer 60 and the printer 40 print a color matching patch based on the patch data B15a2. Since the calibration patch is a patch for grasping the output characteristics of each ink, the patch data A15a1 is CMYKlclm color system image data indicating gradation of each component of CMYKlclm. Since the color matching patch is a patch for evaluating the output ICC profile 15c, the patch data B15a2 is sRGB color system image data.

  The color conversion module 21b is a module that converts a color system indicating the color of each pixel, and appropriately refers to the input ICC profile 15b recorded in the HDD 15 to make the sRGB color system of the image data 15a (15a2) non-device dependent. Conversion to the CIELAB color system which is a color system. Further, the color conversion module 21b refers to the output ICC profile 15c recorded in the HDD 15 as needed, and the image data 15a (15a2) converted into the CIELAB color system is the component of the ink color (CMYKlclm) mounted in the printer 40. Convert to CMYKlclm color system. The input ICC profile 15b and the output ICC profile 15c are tables describing the correspondence relationship between the sRGB color system and the CMYKlclm color system, which are device-independent, for a plurality of colors.

  Accordingly, with respect to an arbitrary color expressed in the sRGB color system, the CIELAB color system corresponding to the arbitrary color is obtained by interpolation when the surrounding color and the sRGB color defined in the input ICC profile 15b are referred to. If the CIELAB color specified in the output ICC profile 15c is referred to, it corresponds to the arbitrary color by interpolation calculation. The color of the CMYKlclm color system can be specified, and color conversion can be performed. Since the patch data A15a1 for printing the calibration patch is CMYKlclm color system image data, it is input to the large / medium / small dot generation module 21d as it is without exceptional color conversion. The output ICC profile 15c is a profile that defines the ink amount including the correction amount of CMYKlclm that is finally ejected, and corresponds to the second ink amount profile of the present invention. Although a default output ICC profile 15c is prepared in advance, an output ICC profile 15c capable of reproducing a certain target color by the printer 40 is created as adjustment data by performing color matching processing described later. That is, a plurality of output ICC profiles 15c are prepared according to the target color.

  The CMYKlclm color system data is image data in which each color of CMYKlclm is expressed with 256 gradations, and each gradation value corresponds to the ink amount of each pixel and each color. That is, a state in which each color ink is not recorded is expressed with a gradation value of 0, and a state in which each color ink is recorded to the maximum with a gradation value of 255 is expressed. For the gradation values 0 to 255, various configurations such as linearly corresponding to the gradation value change and the ink amount change, or linearly corresponding to the gradation value change and the lightness change can be adopted.

  The printer 40 according to the present embodiment can eject large, medium, and small dots as described above, and the large, medium, and small dot generation module 21c indicates the recording amount of large, medium, and small dots for each color based on the 256-level CMYKlclm data. Convert to data. That is, the HDD 15 stores a large / medium / small distribution table 15d in which each gradation value of CMYKlclm is associated with a gradation value indicating the recording amount of large / medium / small dots. With reference to the table 15d, each gradation value of CMKYlclm is converted into a gradation value of large, medium and small dots for each color.

  In this embodiment, the number of gradations of large, medium, and small dots is larger than the number of gradations of CMYKlclm, and is expressed by 12 bits (4096 gradations). In the gradation value of large, medium, and small dots, a state in which large, medium, and small dots are not recorded is represented by a gradation value 0, and a state in which large, medium, and small dots are recorded to the maximum is represented by a gradation value 4095. In the gradation values 0 to 4095, the gradation value change and the dot number change of the large, medium, and small ink droplets correspond linearly, or the lightness change in the state where the gradation value change and the large, medium, and small inks are recorded. Various configurations such as linearly corresponding to the above can be adopted.

  The gradation values of large, medium and small dots can be determined by various methods. For example, a gradation change of CMYKlclm is expressed only by a large dot by associating a gradation value of only a large dot with a gradation value 0 to 255 of CMYKlclm, and then a part of the large dot is expressed with an equivalent brightness. It can be determined by replacing with small dots or medium dots. In this determination, the recording amount of large, medium, and small dots is determined so that banding and bleeding do not occur during the above replacement.

  The large / medium / small sorting table 15 d recorded in advance in the HDD 15 is data determined for the standard printer 71. That is, the manufacturer of the printer 40 prepares the standard printer 71 in advance at the manufacturing stage of the printer 40, and the output color of the individual printer 40 when printing is performed with reference to the large / medium / small sorting table 15d. Adjust the ink discharge amount so that it is almost equivalent to the output color of the standard machine. In the present embodiment, the large / medium / small sorting table 15 d is recorded on a predetermined recording medium when the individual printer 40 is shipped, and is copied from the recording medium to the HDD 15 when installed on the computer 10. In the present embodiment, the default large / medium / small distribution table 15d is referred to in the initial state, but the large / medium / small distribution table 15d adjusted by calibration is referred to after calibration processing described later.

  FIG. 3 is a diagram showing an example of the large / medium / small distribution table 15d. In the drawing, large, medium, and small sorting standard machine data of a certain color is shown, the horizontal axis indicates the CMYKlclm gradation value, and the vertical axis indicates the recording amount of large, medium, and small ink droplets. In FIG. 2, the ink recording amount is shown by both the gradation value and the dot recording rate (%), the vertical axis on the right side is the gradation value (0 to 4095), and the vertical axis on the left side is the dot recording rate. It is. Here, the “dot recording rate” means a ratio of pixels in which dots are formed among pixels in the region when a uniform region is reproduced according to a certain gradation value. Since the CMYKlclm ink amounts finally discharged by the printer 40 are defined by the large / medium / small distribution table 15d, the large / medium / small distribution table 15d corresponds to the second ink amount table of the present invention.

  In the present embodiment, as described above, high-precision color reproduction is realized by using the fact that the number of large, medium, and small dots is larger than the number of gradations of CMYKlclm. That is, if the number of gradations of CMYKlclm is the same as the number of gradations of large, medium, and small dots, the minimum change of large, medium, and small dots corresponding to the minimum change “1” of the CMYKlclm gradation value is also “1”. . However, if the number of gradations of large, medium, and small dots is greater than the number of gradations of CMYKlclm, the minimum change “1” of the large, medium, and small dots can correspond to a smaller change than the minimum change “1” of the CMYKlclm gradation value. Therefore, highly accurate color reproduction can be realized by correcting the gradation value of CMYKlclm below the decimal point.

  The halftone processing module 21d refers to the gradation values of the large, medium, and small dots generated as described above, and realizes recording corresponding to the ink amount corresponding to each gradation value by the printer 40 for each pixel. Perform halftone processing to reduce the number of gradations. That is, halftone image data specifying the ejection / non-ejection of ink and the amount of ink to be ejected (either large, medium, or small) is generated for each pixel. The print data generation module 21e receives the halftone image data, rearranges the data in the order used by the printer 40, and sequentially outputs the halftone image data to the printer 40 in units of data used in one main scan.

  That is, in the printer 40, an ejection nozzle row is mounted as an ink ejection device, and a plurality of ejection nozzles are arranged in parallel in the sub-scanning direction in the nozzle row. used. Therefore, the data to be used at the same time among the data arranged in the main scanning direction is rearranged in order so that the printer 40 can simultaneously buffer the data. The print data generation module 21e generates print data by adding predetermined information such as image resolution to the rearranged data, and outputs the print data to the printer 40 via the USB I / O 19b. When all the data necessary to form an image is transferred by the printer 40, the image is formed on the print medium by the printer 40.

  In addition to the above modules, the PRTDRV 21 incorporates a color matching module 21f, a calibration module 21g, and a color adjustment management module 21h. The color matching module 21f, the calibration module 21g, and the color adjustment management module 21h do not need to be incorporated in the PRTDRV 21 and may be realized by independent applications. The color adjustment management module 21h is a module that controls the color matching module 21f and the calibration module 21g. Details of the color matching process and the calibration process executed by the color matching module 21f and the calibration module 21g will be described in detail later. First, the purpose and effect of the color matching process and the calibration process will be schematically described.

  FIG. 4 schematically compares color matching and calibration. In the figure, the upper part shows the outline of the calibration process, and the lower part shows the outline of the color matching process. The calibration process is executed by printing calibration patches with the standard printer 71 and the printer 40 based on the patch data A15a1 and comparing the colorimetric values of the calibration patches. The patch data A15a1 is CMYKlclm color system image data, and according to the patch data A15a1, a calibration patch representing a one-dimensional gradation of 32 gradations is printed for each component of CMYKlclm. Since the colorimetric values of the calibration patches by the standard printer 71 are prepared in advance as standard color data 73, the standard color data 73 received from the server 60 and the colorimetric values of the calibration patches by the printer 40 are Will be compared.

  Originally, since the printing was performed based on the same patch data A15a1, the two colorimetric values should match, but there may be a color difference between the two due to an error in the printer 40 or the printing medium. Therefore, in the calibration process, adjustment data is created based on the comparison result between the two, and the adjustment data is fed back to the large / medium / small distribution table 15d. According to the large / medium / small distribution table 15 d, the amount of ink ejected can be adjusted, so that the color that the printer 40 finally reproduces can be adjusted to match the standard color data 73. By performing the above calibration, the reproduced color of the printer 40 can be matched with the reproduced color of the printer 71, and an error of the reproduced color unique to the printer 40 can be prevented.

  In particular, the CMYKlclm ink can be accurately grasped because the CMYKlclm ink components depend on the printer 40 because the error is corrected and corrected for each component of CMYKlclm by a calibration patch representing a one-dimensional gradation of 32 gradations. Since the large / medium / small distribution table 15d to be adjusted is also independent for each CMYKlclm component, it can be adjusted according to the output characteristics of each ink component. The large / medium / small distribution table 15d may be overwritten each time calibration is performed, or the large / medium / small distribution table 15d for each calibration is sequentially stored, and the latest one is used by the large / medium / small dot generation module 21c. You may be made to do.

  The color matching process is executed by printing a color matching patch using the digital screen printer 60 and the printer 40 based on the patch data B15a2 and comparing the colorimetric values of the color matching patch. The patch data B15a2 is image data of the sRGB color system or the CMYK color system, and the color matching patch based on the patch data B15a2 is printed by the printer 40 while performing color conversion with reference to the default output ICC profile 15c. Is done. The colors of the color matching patches are selected so as to cover the entire gamut of the digital screen printer 60 and the printer 40 substantially uniformly, and the reproduction colors of the digital screen printer 60 and the printer 40 are compared for the entire gamut. Is done. Specifically, the correspondence between the colorimetric values of the digital screen printer 60 and the printer 40 is compared in the CIELAB color space, which is a non-device-dependent color space. As a result of this comparison, an output ICC profile 15c in which the ink amount that can realize the reproduction color of the digital screen printer 60 is newly created and stored in the HDD 15. As described above, although the calibration process and the color matching process are common in that the patch is output / colorimetrically, the adjustment target is different, and the characteristics of the patch printed according to each purpose are greatly different. Hereinafter, various management processes in which the color adjustment management module 21h comprehensively manages the calibration process and the color matching process will be described in detail.

(2) Various Management Processing FIG. 5 shows the flow of calibration management processing executed by the color adjustment management module 21h. When the color adjustment management module 21h receives an instruction to execute calibration in step S100, the color adjustment management module 21h causes the calibration module 21g to execute a calibration process described later in step S110. When the calibration process is executed, the large / medium / small sorting table 15d is updated, and the reproduction color of the printer 40 matches the standard printer 71. In step S120, the HDD 15 stores calibration history data 15e storing the fact that the color adjustment management module 21h has performed calibration and the date and time of calibration. When the calibration history data 15e is already stored by the calibration process performed in the past, the calibration history data 15e is updated with the latest information. As a result, the date and time of the last calibration process is recorded in the calibration history data 15e.

  FIG. 6 shows the flow of print management processing executed by the color adjustment management module 21h. In step S200, a print instruction is accepted. When the print instruction is received, in step S210, the color adjustment management module 21h acquires the calibration history data 15e, and determines whether to permit the use of the output ICC profile 15c. Here, the date and time of the last calibration process is compared with the current date and time, and it is determined whether or not a predetermined effective period has elapsed. When the valid period has not elapsed, the use of the output ICC profile 15c is permitted, and when the valid period has elapsed, the use of the output ICC profile 15c is not permitted. The effective period is set on the basis of the temporal change characteristic of the reproduced color of the printer 40. For example, a period in which an allowable limit of color difference occurs is statistically investigated, and the period can be set as the effective period.

  When permitting use of the output ICC profile 15c, designation of the output ICC profile 15c used for printing is accepted in step S220. Since the output ICC profile 15c is created for each target color by a color matching process described later, one corresponding to a desired target color can be selected with a predetermined UI. If the calibration process is performed within a predetermined effective period, the use is permitted for all the output ICC profiles 15c in step S210. Therefore, the selected output ICC profile is selected regardless of which output ICC profile 15c is selected. 15c can be used. In step S230, the printing process is actually executed. Specifically, the image data acquisition module 21a, the color conversion module 21b, the large / medium / small dot generation module 21c, the halftone processing module 21d, the print data generation module 21e, and the printer 40 are driven, and the printing process is performed by the above-described series of procedures. Let it run. At that time, since the color conversion module 21b refers to the output ICC profile 15c selected in step S220, the desired target color can be reproduced.

  On the other hand, if the use of the output ICC profile 15c is not permitted in step S210, the calibration module 21g is caused to execute the calibration process in step S240, and the calibration is performed at the date and time as in steps S110 and S120 of FIG. Update history data 15e. Then, the process returns to step S210, and it is determined again whether or not the use of the ICC profile 15c is permitted. Basically, since the calibration history data 15e has been updated by the previous calibration process, the use of the output ICC profile 15c is permitted. As described above, by using the calibration management process and the print management process shown in FIGS. 5 and 6, the use of the output ICC profile 15c is permitted on the condition that the calibration is performed within the valid period. Can do.

  In other words, the output ICC profile 15c can be used only in the printer 40 in which the valid period has not elapsed since the calibration, or in the printer 40 in which the valid period has once been calibrated but has been calibrated again. Therefore, it is possible to accurately reproduce a desired target color without being affected by a machine error or a time-dependent error of the reproduction color of the printer 40. For example, when the output ICC profile 15c created using the digital screen printer 60 as the target color is selected, the proofing of the printable result in the digital screen printer 60 can be easily realized by the printer 40.

  In this embodiment, the use permission / prohibition of the output ICC profile 15c is determined based on the timing of calibration performed in the past. However, the use permission / prohibition is determined based on the coincidence between the calibration condition and the printing condition. Also good. For example, a print sheet on which a calibration patch is printed is recorded in the calibration history data 15e, and the use of the output ICC profile 15c is permitted only when the print sheet matches the print sheet specified by the print instruction. It may be. In this way, it can be ensured that the calibration for the printing paper instructed to be printed has been performed, and accurate color reproduction can be guaranteed on the printing paper. In the calibration management process and the print management process shown in FIGS. 5 and 6, the output ICC profile 15c as the adjustment data of the ink amount profile created by the color matching is used on the condition that the calibration has been performed. Therefore, it can be said that the color adjustment management module 21h that executes these processes specifically realizes the calibration apparatus of the present invention.

  FIG. 7 shows the flow of color matching management processing executed by the color adjustment management module 21h. In step S300, the color adjustment management module 21h receives an instruction to execute color matching. In step S310, the color adjustment management module 21h acquires the calibration history data 15e, and determines whether calibration has been performed within the valid period. When the calibration is performed within the effective period, the execution of the color matching process is permitted, and when the calibration is not performed within the effective period, the execution of the color matching process is not permitted. The valid period used in step S310 can be the same as that in step S210 described above. Of course, it is possible to set different effective periods.

  If it is determined in step S310 that the execution of the color matching process is permitted, the color adjustment management module 21h causes the color matching module 21f to execute a color matching process described later in step S320. On the other hand, if it is determined in step S310 that the execution of the color matching process is permitted, the calibration module 21g is caused to execute the calibration process in step S330 in the same manner as in steps S110 and S120 in FIG. The calibration history data 15e is updated. Then, the process returns to step S310, and it is determined again whether or not the execution of the color matching process is permitted. Basically, since the calibration history data 15e has been updated by the previous calibration process, the execution of the color matching process is permitted. As described above, by performing the calibration management process and the color matching management process shown in FIGS. 5 and 7, the execution of the color matching process is permitted on the condition that the calibration is performed within the effective period. Can do.

  That is, it is possible to execute the color matching process only in the printer 40 in which the valid period has not elapsed since the calibration, or in the printer 40 in which the valid period has been once calibrated but has been calibrated again. Therefore, it is possible to realize a color matching process that is not affected by a machine error or a time-dependent error of the reproduced color of the printer 40. Accordingly, the output ICC profile 15c created by the color matching process can also be prevented from being affected by the machine error or the time-dependent error of the reproduced color of the printer 40. In the color matching management process shown in FIG. 7, the color matching process for adjusting the output ICC profile 15c as the first ink amount profile can be executed on the condition that the calibration has been performed. It can be said that the color adjustment management module 21h that executes the above has specifically realized the main part of the color adjustment system and color matching apparatus of the present invention. If the color matching management process as described above is assumed, an output ICC profile 15c that does not depend on the reproduction color characteristics of each printer 40 can be created, and the created output ICC profile 15c is highly versatile.

  That is, since the output ICC profile 15c is guaranteed to have been created for the printer 40 that has just been calibrated and the reproduction color matches that of the standard printer 71, the output ICC profile 15c is the same as that of the standard printer 71 and reproduction color. It can be said that it can be used without any loss of accuracy in any printer that meets the above. Since the reproduction color can be matched with the reproduction color of the standard printer 71 by performing the calibration process in any printer in advance, the output ICC profile 15c created by a certain printer can be used accurately in virtually any printer. It can be said that it can be. Therefore, the output ICC profile 15c created for a certain printer can be exported or copied for use by another printer.

  FIG. 8 schematically shows how the output ICC profile 15c is exported and used. In the figure, printers 40a and 40b are provided for two computers 10a and 10b connected via the Internet INT, respectively. Both the computers 10a and 10b are assumed to have the specific configuration shown in FIG. Here, it is assumed that the output ICC profile 15c for a certain target color is created by the processing according to FIG. 7 in the computer 10a. Since it is ensured that the calibration of the printer 40a is executed within the effective period by step S310, the ICC profile 15c is adapted to the standard printer 71 without being affected by the machine error or the time error of the printer 40a. It becomes.

  The output ICC profile 15c created by the computer 10a is exported to another computer 10b, and the print management processing shown in FIG. 6 is executed by the computer 10b. In the print management process shown in FIG. 6, in step S210, the use of the imported output ICC profile 15c is permitted on the condition that the calibration of the printer 40b is executed within the valid period. Accordingly, when the output ICC profile 15c is used, the printer 40b is created so as to be compatible with the standard printer 71 in order to reproduce the same color as the standard printer 71 without being affected by the machine error and the time error. The target color can be accurately reproduced based on the ICC profile 15c.

  As described above, even when the creation and use of the output ICC profile 15c is performed by different printers 40a and 40b, by executing the calibration process for both the creation and use of the output ICC profile 15c, Both printers 40a and 40b can share the output ICC profile 15c with high accuracy. When color matching is performed without performing calibration, an original adjustment component for matching the adjustment amount of the generated output ICC profile 15c with the target color and an adjustment component for matching the reproduced color with the standard printer 71 are obtained. It will be included. Such an output ICC profile 15c is usable only for the printer. On the other hand, if the calibration is conditioned prior to the color matching, the adjustment component for matching the reproduced color with the standard printer 71 can be excluded from the adjustment amount of the output ICC profile 15c, so that it does not depend on the printer. A highly versatile output ICC profile 15c can be created. Therefore, it is not necessary to perform color matching every time each target color is set in each printer, and the burden of color matching processing can be reduced. As will be described later, since the processing load of the color matching process is larger than that of the calibration process, the effect of the present invention that can suppress the undue execution of the color matching process is great.

  The large / medium / small sorting table 15d is adjusted by calibration, and the output ICC profile 15c is adjusted (created) by color matching. As described above, since the ink amount profiles adjusted by both processes are independent from each other, only the highly versatile output ICC profile 15c independent of the printer can be handled independently, and export and copying can be easily performed. be able to.

(3) Calibration Process Next, the above-described calibration process will be described in detail based on the flow shown in FIG. The PRTDRV 21 includes a calibration module 21g. The calibration module 21g can be instructed from the printer property screen or can be activated by a command from the color adjustment management module 21h. When the calibration module 21g is activated, patch data A15a1 is first acquired from the HDD 15 in step S400.

  In step S405, the gradation value of each ink color is grasped from the patch data A15a1, print data for executing printing with the gradation value is generated, and the patch is printed. The patch data A15a1 is CMYKlclm color system image data, and is transferred to the large, medium, and small dot generation module 21c without color conversion, and the large, medium, and small dot generation module 21c receives the received patch data A15a1 and the above-described patch data A15a1. With reference to the large / medium / small distribution table 15d, print data expressing the color of the patch with the gradation values of large / medium / small dots is generated. The patch data A15a1 is converted into print data by processing in the halftone processing module 21d and the print data generation module 21e. As a result, the printer 40 prints a plurality of calibration patches.

  FIG. 10 shows an example of a calibration patch. In the figure, a gradation of 32 gradations in which the density is gradually changed for each ink of CMYKlclm is formed by the calibration patch. For example, in a calibration patch for C ink, the dot recording rate for C ink gradually changes, and the dot recording rate for other MYKlclm ink components is zero. The user measures the color of each printed calibration patch using the colorimeter 50. In step S110, the calibration module 21g outputs control data for outputting colorimetric data via the USB I / O 19b, and the colorimeter 50 measures the CIELAB value of each patch according to the control data. Output color data. The calibration module 21g acquires the color measurement data.

  The calibration module 21g compares the colorimetric data with the standard color data 73 received from the server 60, and outputs a color as close as possible to the color to be output in the CMYKlclm gradation value defined by the patch data A15a1. Thus, the large, medium, and small dot gradation values are corrected, and the large, medium, and small distribution table 15d is created. First, in step S415, an interpolation function for obtaining a CIELAB value for an arbitrary CMYKlclm gradation value in an individual printer is calculated. The standard color data 73 is not limited to the data received from the server 70 during the calibration process, and may be stored in the HDD 15 when the PRDRV 21 is installed, for example.

  This interpolation function is a function created by referring to the correspondence relationship between the CMYKlclm gradation values and CIELAB values defined by the patch data A15a1 shown in the colorimetric data, and between the gradation values of each CMYKlclm. Is a function that approximately describes the correspondence between the two. Various methods can be employed as a method for calculating this function. For example, a function form of a higher-order function using a gradation value or CIELAB value as a variable is determined in advance, and the CIELAB value is calculated from the CIELAB value at each gradation value. It is possible to determine a function by calculating a coefficient of a higher order function. Of course, since the colorimetric data includes a colorimetric error, the degree of change of the function is made as smooth as possible without accurately correlating each gradation value with the CIELAB value, or obtained by using each CIELAB value and the interpolation function. Various configurations such as a configuration in which an error from a given value is minimized as a whole can be adopted. When the interpolation function is obtained, data indicating the interpolation function is stored in a RAM (not shown) or the like.

  In step S420, the standard color data 73 recorded in advance in the HDD 15 is acquired. In steps S425 to S445, a color to be output is specified by the CMYKlclm gradation value defined by the patch data A15a1, and a CIELAB value for outputting the output color by the individual printer 40 is calculated. At the same time, the large, medium, and small dot gradation values for obtaining the output of the CIELAB value are acquired. The acquired large, medium, and small dot gradation values are associated with CMYKlclm gradation values.

  More specifically, the CIELAB value corresponding to a certain CMYKlclm gradation value is acquired by referring to the standard color data 73 in step S425. In steps S425 to S450, the process proceeds with the CMYKlclm tone value as a processing target. In step S425, a CIELAB value that has a minimum color difference with respect to the acquired CIELAB value is calculated from the CIELAB values obtained by the interpolation function. That is, a color that is the closest to the output color at the target gradation value in the standard color data 73 and that can be output by the individual printer 40 is acquired for each ink color.

FIG. 11 is an explanatory diagram for explaining the processing here. In the figure, the horizontal axis is the a ^* value in the L ^* a ^* b ^* color space, and the vertical axis is the b ^* value. That is, the CIELAB values (L ^* a ^* b ^* values) in the L ^* a ^* b ^* color space, which is a three-dimensional color space, are projected onto the a ^* b ^* plane. Further, in the figure, as an example, a state in which the color values of C ink are plotted is shown. White circles in the figure are projection values of the colorimetric data, and are color values corresponding to the gradation values “7, 14,..., 252” in order from the white circle close to the origin O along the curve. The black circles in the figure are the projection values of the standard color data 73, and are the color values corresponding to the gradation values “7, 14,... 252” in order from the black circle close to the origin O along the curve.

  In the enlarged view A of FIG. 11, the white circles shown as the colorimetric data are CIELAB values of colors printed by the individual printers 40 based on the gradation values 77 and 84, and the nearby curve is calculated by the above interpolation function. CIELAB values are projected. Similarly, a black circle shown as the standard color data 73 is a CIELAB value (Vs) of a color printed by a standard printer with a gradation value 77.

  When the individual printer 40 outputs a color by changing the gradation value for each color, the CIELAB value is substantially equal to the CIELAB value calculated by the interpolation function (located on the projection curve in FIG. 11). . Therefore, in order to eliminate the color shift by correcting each color, a CIELAB value as close as possible to the value Vs is extracted from the CIELAB values calculated by the interpolation function. For this reason, in step S425, a CIELAB value calculated by an interpolation function and a CIELAB value that has a minimum color difference (minΔE) with respect to the value Vs is calculated. Since the interpolation function uses only the target ink gradation value (only C ink gradation in FIG. 11) as a variable, the number of parameters for determining the interpolation function is small, and the processing load when determining the interpolation function is reduced. Less is enough.

  In step S430, a gradation value corresponding to the CIELAB value that is the minimum color difference is acquired based on the interpolation function. In the example shown in FIG. 11, this gradation value is 80.24. In the present embodiment, since the interpolation function is continuously defined, a value equal to or less than an integer value can be defined, and a gradation value including a value after the decimal point is calculated. At this time, in order to output the correction value of the gradation value in the individual printer 40, that is, the color to be output with the gradation value 77, the gradation value is corrected by 3.24. , 80.24. In the present embodiment, the gradation value of large, medium, and small dots is 4096 gradations, the CMYKlclm gradation value is 256 gradations, and the former is calculated up to two digits after the decimal point because the resolution is 16 times that of the latter. However, the number of digits adopted after the decimal point can be appropriately changed depending on the resolution.

  When the gradation value is found, the standard color data 73 is acquired in step S435, and the large, medium, and small dot gradation values corresponding to the gradation value are acquired in step S440. In step S445, the acquired gradation values of large, medium, and small dots are associated with the gradation values to be processed in step S425 and subsequent steps and stored in a RAM (not shown). That is, the gradation values are associated with each other so that ink droplets are output according to the large, medium, and small dot gradation values acquired in step S440.

  Here, by extracting the gradation values of large, medium, and small dots corresponding to the CMYKlclm gradation values after the decimal point, it is possible to correct color misalignment with high accuracy and to prevent occurrence of gradation collapse and tone jump. This will be described with reference to an enlarged view B of FIG. The enlarged view B shows an example in which the color to be output at the gradation value 77 corresponds to the gradation value 80.24 in the individual printer 40 as in the above example. The straight line shown in the enlarged view shows the gradation value of the medium dot defined by the standard color data 73. When only the integer value of the CMYKlclm gradation value is considered, the gradation value of the medium dot is Only the value b1 or b2 corresponding to the CMYKlclm gradation value 80 or 81 can be selected.

  However, the exact color to be output with the gradation value 77 corresponds to the CMYKlclm gradation value 80.24. In this embodiment, since the number of gradations of the large, medium, and small dots is 4096, an intermediate value between the values b1 and b2 can be selected, and a more accurate gradation value of the large, medium, and small dots can be selected. It can be associated with the gradation value 77. In other words, if only integer values are considered as CMYKlclm gradation values, correct gradation values of large, medium, and small dots cannot be selected by correction, and colors that should not be output in the same color are output to the same color. Distortions such as output of different colors for the same color occur, resulting in gradation collapse and tone jump. In this embodiment, gradation collapse and tone due to such causes are generated. No jump occurs.

  Further, the gradation values of large, medium, and small dots that can be selected are gradation values determined in advance in the standard color data 73. That is, one of the recording amount balances of large, medium, and small dots previously defined in the standard color data 73 is selected. In the standard color data 73, in consideration of many conditions for printing a high-quality image, the balance and recording amount of large, medium, and small dots are determined by adjusting in very detail. Accordingly, when correcting the color misregistration, the standard color data 73 is ignored and, for example, a correction that increases the recording amount of small dots and decreases the recording amount of medium dots by focusing on matching the CIELAB values in FIG. Etc., the image quality may be degraded. However, in this embodiment, since the gradation values of large, medium, and small dots defined in the standard color data 73 are used as they are, color correction can be performed without degrading the image quality.

  As described above, when the gradation values of the large, medium, and small dots are associated with the target gradation values in step S445, in step S450, all of the plurality of target gradation values have been processed as processing targets. In step S450, the processes in and after step S425 are repeated until it is determined that the processing has been completed for all of the plurality of target gradation values. If it is determined in step S450 that the processing has been completed for all of the plurality of CMYLlclm tone values, the correspondence stored in the RAM (not shown) is updated to the HDD 15 as the adjusted large / medium / small distribution table 15d.

  In the large / medium / small distribution table 15d created as described above, a plurality of target gradation values and large / medium / small dot gradation values are associated with each color, and the associated large / medium / small dot gradation values are associated with each other. According to this, it is possible to output a color as close as possible to the color to be output according to the target gradation value. Therefore, the large, medium, and small dot generation module 21c refers to the large, medium, and small sorting table 15d to convert any CMYKlclm gradation value into a large, medium, and small dot gradation value, thereby causing color misregistration between the individual printer 40 and the standard printer 71. Printing can be executed while correcting the above.

  In this embodiment, the color misregistration is eliminated by correcting each ink color, but the correction target is data for large / medium / small distribution, and the CMYKlclm floor defined in the output ICC profile 15c. The tone value is not changed, and the correspondence relationship between the CMYKlclm tone value and the tone value of the large, medium, and small dots is changed. Therefore, it is possible to prevent the occurrence of gradation collapse and tone jump. Further, it is configured so that the number of gradations of large, medium, and small dots is larger than the number of gradations of the CMYKlclm gradation value, and the gradation change corresponding to the decimal point of the CMYKlclm gradation value is also considered. Therefore, it is possible to correct the color misregistration with high accuracy. The above processing is executed in the calibration processing performed in step S110 in FIG. 5, step S240 in FIG. 6, and step S330 in FIG.

(4) Color Matching Processing FIG. 12 shows the flow of color matching processing. The PRTDRV 21 includes a color matching module 21f, and the color matching module 21f can be activated by instructing the execution of color matching from the property screen of the printer. When the color matching module 21f is activated, patch data B15a2 is first acquired from the HDD 15 in step S500. In step S505, the gradation value of each ink color is grasped from the patch data B15a2, print data for executing printing with the gradation value is generated, and the patch is printed. The color of the color matching patch is set so as to cover the entire color space substantially uniformly in order to accurately perform the interpolation calculation described later.

When the patch data B15a2 is sRGB color system image data, the color conversion module 21b performs sRGB → L ^* a ^* b ^* conversion with reference to the input ICC profile 15b. The sRGB value corresponding to each i-th patch (i = 1 to n, where n is the total number of patches) is represented as (R _pi , G _pi , B _pi ), and the CIELAB conversion value is represented as a patch correspondence value (L _pi , _api , _bpi ). Further, the gradation value of each ink is grasped by referring to the output ICC profile 15c and performing L ^* a ^* b ^* → CMYKlclm conversion. The ink gradation values obtained by converting the patch correspondence values (L _pi , a _pi , b _pi ) are defined as (C _pi , M _pi , Y _pi , K _pi , lc _pi , lm _pi ). The output ICC profile 15c is an ink tone value (C _gj , M _gj , Y _gj , K _gj , lc) corresponding to each grid point (L _gj , a _gj , b _gj ) that covers the entire CIELAB color space in a grid pattern. _gj , lm _gj ). Accordingly, for the patch corresponding values (L _pi , a _pi , b _pi ) that are not present at the respective grid points (L _gj , a _gj , b _gj ), the ink gradation values (C _pi , M _pi , Y _pi , K) are obtained by interpolation. _pi , lc _pi , lm _pi ). Note that j is an integer from 1 to m, and m represents the total number of grid points defined in the output ICC profile 15c.

The gradation values (C _pi , M _pi , Y _pi , K _pi , lc _pi , lm _pi ) of each ink obtained by the above color conversion are passed to the large / medium / small dot generation module 21 c, and The dot generation module 21c refers to the large / medium / small distribution table 15d adjusted by the pre-calibration process, and generates print data that expresses the color of the patch with the gradation values of large / medium / small dots. This print data is further converted by the processing in the halftone processing module 21d and the print data generation module 21e. As a result, the printer 40 prints a plurality of color matching patches. In step S <b> 510, each color matching patch printed by the printer 40 is measured by the colorimeter 50. In step S510, the color matching module 21f outputs control data for outputting colorimetric data via the USB I / O 19b, and the colorimeter 50 measures the CIELAB value indicating each patch according to the control data. Output color data. The color matching module 21f acquires the color measurement data. The colorimetric value of each patch acquired here is expressed as (L _pmi , a _pmi , b _pmi ).

In step S515, the patch data B15a2 is output to the digital screen printing machine 60, and the color matching patch is printed by the digital screen printing machine 60. In step S520, the color matching patch printed by the digital screen printer 60 is measured by the printing colorimeter 50. The colorimetric values acquired here are _expressed as target colorimetric values (L _pti , a _pti , b _pti ). In step S525, ink gradation values (C _pxi , M _pxi , Y _pxi , K _pxi , lc _pxi , lm _pxi ) such that the target colorimetric values (L _pti , a _pti , b _pti ) can be reproduced by the printer 40. ) Is calculated.

FIG. 13 schematically illustrates the calculation process in step S525. Ink tone values corresponding to the patch for each color matching in step _{S510 (C pi, M pi,} Y pi, K pi, lc pi, lm pi) and colorimetric the colorimetric values _{(L pmi, a pmi, b} pmi ), The spatial positional relationship between them can be grasped as shown in FIG. In FIG. 13, the CM plane and the a ^* b ^* plane are projected to simplify the drawing, and i = 1 to 4th color matching patches are plotted. Here, when the target colorimetric values (a _pt1 , b _pt1 ) of the first patch exist in the area surrounded by the four points of the colorimetric values (a _pmi , b _pmi ) on the a ^* b ^* plane, a ^* b ^{* The} surrounding ink tone values (C) are weighted according to the positional relationship between the four colorimetric values (a _pmi , b _pmi ) and the target colorimetric values (a _pt1 , b _pt1 ) on the plane. _pi, by adding the M _pi), it is possible to calculate ink gradation value corresponding to the target color measurement value (a _pt1, b _pt1) a (C _px1, M _px1). Actually, three-dimensional volume interpolation is performed instead of a plane. Ink gradation values (C _pxi , M _pxi , Y _pxi , K _pxi , lc _pxi , lm _pxi ) are calculated for all patches (i = 1 to n) in the same procedure as above.

Ink gradation values (C _pxi , M _pxi , Y _pxi , K _pxi , lc _pxi , lm _pxi) that can obtain the same reproduction color as each color matching patch printed by the digital screen printer 60 as described above. ) Can be specified, the ink gradation values (C _pxi , M _pxi , Y _pxi , K _pxi , lc _pxi , lm _pxi ) and the patch correspondence values (L _pi , a temporary profile is created in which a _pi , b _pi ) are associated with each color matching patch. This temporary profile defines the correspondence between CIELAB values and CMYKlclm values for each color matching patch color, and the digital screen printer 60 performs color conversion of the patch data B15a2 based on the temporary profile. The printer 40 can obtain reproduced colors that are the same color as the printed color matching patches. In step S535, the CMYKlclm value corresponding to each grid point (L _gj , a _gj , b _gj ) defined in the output ICC profile 15c is calculated based on the correspondence defined in the temporary profile.

FIG. 14 schematically illustrates the calculation process in step S535. Since the temporary profile is obtained in advance, as shown in FIG. 14, for the color of the color matching patch, the patch correspondence values (L _pi , a _pi , b _pi ) obtained in the color conversion process and the ink gradation values (C _pxi) , M _pxi , Y _pxi , K _pxi , lc _pxi , lm _pxi ) can be grasped in the CIELAB color space and the CMYKlclm color space. Also in FIG. 14, the CM plane and the a ^* b ^* plane are projected to simplify the drawing, and i = 1 to 4th color matching patches are plotted. Here, the first (j = 1) grid point gradation value ( _{ag 1} , b _g1 ) exists in an area surrounded by four points of the patch correspondence values (a _pi , b _pi ) on the a ^* b ^* plane. In this case, the surrounding ink is weighted according to the positional relationship between the patch correspondence values (a _pi , b _pi ) of the four points on the a ^* b ^* plane and the grid point gradation values (a _g1 , b _g1 ). By adding the gradation values (C _pi , M _pi ), the ink gradation values (C _g1 , M _g1 ) corresponding to the lattice point gradation values (a _g1 , b _g1 ) can be calculated. Actually, volume interpolation based on a three-dimensional spatial positional relationship is performed instead of a plane. Ink gradation values (C _gj , M _gj , Y _gj , K _gj , lc _gj , lm _gj ) are calculated for all grid points (j = 1 to m) by the same procedure as above. Thus, each value constituting the output ICC profile 15c can be calculated.

In step S540, the new output ICC profile 15c storing the ink gradation values (C _gj , M _gj , Y _gj , K _gj , lc _gj , lm _gj ) calculated in step S535 is stored in the HDD 15 as adjustment data. To finish the color matching process. The color difference average between the colorimetric values (L _pmi , a _pmi , b _pmi ) acquired in step S510 and the target colorimetric values (L _pti , a _pti , b _pti ) acquired in step S520 is calculated. The output ICC profile 15c with higher accuracy may be created by repeating steps S500 to S540 until the color difference average falls below a predetermined threshold. By performing color conversion with reference to the output ICC profile 15c, the printer 40 can realize the same reproduction color as that of the digital screen printer 60. In color matching processing as in steps S525 and S535, since the correspondence in the color space needs to be specified by three-dimensional interpolation, the processing load is large. Further, when the color matching is repeatedly performed as described above to obtain the high-precision output ICC profile 15c, the processing burden is further increased.

It is a block diagram which shows schematic structure of a color adjustment system. It is a block diagram which shows schematic structure of a computer. It is a figure which shows the example of a large / medium / small distribution table. It is a comparison explanatory drawing of color matching and calibration. It is a flowchart of a calibration management process. 10 is a flowchart of print management processing. It is a flowchart of a color matching management process. It is a block diagram which shows the application structure of a color adjustment system. It is a flowchart of a calibration process. It is a figure which shows the example of the patch for calibration. It is explanatory drawing explaining the process at the time of correcting a color. It is a flowchart of a color matching process. It is explanatory drawing explaining spatial interpolation. It is explanatory drawing explaining spatial interpolation.

Explanation of symbols

  10 (10a, 10b) ... Computer, 15a ... Image data, 15a1 ... Patch data A, 15a2 ... Patch data B, 15b ... Input ICC profile, 15c ... Output ICC profile (adjustment data), 15d ... Large, medium and small sorting table, 15e ... Calibration history data, 21 ... PTDRV, 21a ... Image data acquisition module, 21b ... Color conversion module, 21c ... Large / medium / small dot generation module, 21d ... H / T processing module, 21e ... Print data generation module, 21f ... Color matching Module, 21g ... Calibration module, 21f ... Color adjustment management module, 40 (40a, 40b) ... Printer, 50 ... Colorimeter, 60 ... Digital screen printer, 70 ... Server, 71 ... Standard printer, 72 ... Colorimetry Machine 73 ... standard color data

Claims (9)

In a color adjustment system that adjusts a color that a printing device reproduces on a recording medium in accordance with image data,
Calibration means for performing calibration for matching the reproduction color by the printing apparatus with a predetermined standard color;
A color adjustment system comprising color matching means for performing color matching that matches a color reproduced by the printing apparatus with a desired target color on the condition that the calibration is performed. The color matching means is
Using the first ink amount profile that defines the spatial correspondence between the predetermined color space and the ink amount space, a plurality of color patches covering the entire color space are printed by the printing apparatus, and the color measurement result is displayed. And adjusting the first ink amount profile based on
The calibration means includes
Using the second ink amount profile that defines the correction amount for each ink amount, a plurality of color patches in which the ink amount of each ink is independently varied in the ink amount space are printed by the printing device, The color adjustment system according to claim 2, wherein the second ink amount profile is adjusted based on a color measurement result. When adjustment data of a profile adjusted by the color matching means is created by performing the calibration and the color matching in a certain printing apparatus, and the calibration is performed in another printing apparatus In addition,
The color adjustment system according to claim 1, wherein the adjustment data is usable in the other printing apparatus. When adjustment data of a profile adjusted by the color matching means is created by performing the calibration and the color matching in a certain printing apparatus, and the calibration is performed again,
The color adjustment system according to claim 1, wherein the adjustment data is usable in the printing apparatus. In a color adjustment method in which a printing apparatus adjusts a color reproduced on a recording medium according to image data,
Calibration for performing calibration to match the reproduction color by the printing apparatus with a predetermined standard color;
And color matching that matches the reproduced color by the printing device with a desired target color on the condition that calibration for matching the reproduced color by the printing device with a predetermined standard color is performed. Color adjustment method. In a color adjustment program for causing a computer to execute a function of adjusting a color reproduced on a recording medium by a printing apparatus according to image data,
A calibration function for performing calibration to match the reproduction color by the printing apparatus with a predetermined standard color;
A color adjustment program for causing a computer to execute a color matching function for performing color matching that matches a reproduced color by the printing apparatus with a desired target color when the calibration is performed. A plurality of printing devices including one printing device, a first processing means for converting the first image data into second image data in a predetermined color space, and the second image data for the first printing. A print control system comprising second processing means for converting to third image data that can be printed by the apparatus, and for obtaining a print result substantially the same as a desired target,
Calibration means for performing calibration for adjusting the second processing means for the first printing apparatus so as to obtain a printing result substantially the same as that of the printing apparatus other than the first printing apparatus;
On condition that the second processing means is adjusted by the calibration means, the first processing means is provided to the first printing apparatus so as to obtain a printing result substantially the same as a desired target. A printing control system comprising color matching means for performing color matching to be adjusted. The calibration means includes
Based on the third image data obtained by converting the second image data, the result of printing by the first printing device is obtained by converting the same second image data by a predetermined printing device. Adjustment is performed so that a printing result substantially the same as the result of printing based on the third image data is obtained,
The color matching means is
Based on the result of printing by the first printing apparatus based on the third image data obtained by converting the first image data, and the same first image data by another printing apparatus as the target The print control system according to claim 7, wherein adjustment is performed so that a print result substantially the same as a print result is obtained. The color matching means is
The same processing as that of the first processing unit adjusted by the color matching unit executed on the condition that the calibration unit is executed on a printing apparatus other than the first printing apparatus is performed. The print control system according to claim 8, wherein the first processing unit in the first printing apparatus is adjusted.

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