JP5736810B2 - Print control apparatus, print control method, and print control program - Google Patents

Description

  The present invention relates to a print control apparatus, a print control method, and a print control program.

  Conventionally, calibration is performed in an ink jet printer to improve color reproducibility. When performing this calibration, a color chart for calibration is printed from the printer. Next, the color chart is color-measured to obtain a colorimetric value in the color space, and the color shift of the printer is corrected based on the colorimetric value.

  For example, in Patent Document 1, a color chart in which a plurality of patches having the same combination of ink color type and dot size type is arranged is printed. Then, for example, an average value of the colorimetric values of the patches having the same combination of the ink color type and the dot size type is obtained, thereby reducing the influence of the mechanical error in the printing apparatus and correcting the color misregistration. Yes.

JP 2007-216569 A

  However, in the case of the color chart described in Patent Document 1, a plurality of patches for each dot size type are printed for each ink color type. For this reason, the number of patches arranged on the color chart inevitably increases, and as a result, the color measurement time becomes longer and the amount of ink consumed for printing the color chart also increases.

  SUMMARY An advantage of some aspects of the invention is to solve at least a part of the problems described above, and the invention can be implemented as the following forms or application examples.

  Application Example 1 A print control apparatus that controls a printing apparatus that prints an image by forming a plurality of types of dots having different dot sizes on a printing medium, and the printing medium includes the printing medium based on predetermined image data. A print control apparatus, comprising: a patch printing unit that prints a patch for each dot type, wherein the patch printing unit controls the number of patches for each dot type according to the dot size.

  According to the above-described printing control apparatus, the patch printing unit controls the number of patches for each dot type according to the dot size, so that the number of patches suitable for each dot size can be printed. Accordingly, the number of patches in the entire color chart can be reduced as compared with the conventional color chart in which the number of patches for each dot type is the same, and as a result, the color measurement time can be shortened. Furthermore, the amount of ink consumed for printing the color chart can be reduced.

  Application Example 2 The print control apparatus, wherein the patch printing unit performs control so that the number of the patches decreases as the dot size decreases.

  According to the print control apparatus described above, control is performed such that the smaller the dot size, the smaller the number of patches. When the dot size is small, it is difficult to be affected by mechanical errors during printing, and therefore color measurement accuracy can be ensured even if the number of patches is reduced.

  Application Example 3 When the upper limit value of the amount of ink that can be ejected in the unit area of the print medium is an ink duty limit value, the patch printing unit has a smaller number of patches as the ink duty limit value is lower. The printing control apparatus according to claim 1, wherein the printing control apparatus is controlled so as to increase.

  According to the print control apparatus described above, control is performed so that the number of patches increases as the ink duty limit value decreases. When the ink duty limit value is low, it is easy to be affected by the background during color measurement, so that the color measurement accuracy can be ensured by increasing the number of patches.

  Application Example 4 A print control method for controlling a printing apparatus that prints an image by forming a plurality of types of dots having different dot sizes on a print medium, the print medium including the dot on the print medium based on predetermined image data A printing control method, comprising: a patch printing step for printing a patch for each dot type, wherein the number of patches for each dot type is controlled in accordance with the dot size in the patch printing step.

  According to the print control method described above, the number of patches suitable for each dot size can be printed in the patch printing process. Accordingly, the number of patches in the entire color chart can be reduced as compared with the conventional color chart in which the number of patches for each dot type is the same, and as a result, the color measurement time can be shortened. Furthermore, the amount of ink consumed for printing the color chart can be reduced.

  Application Example 5 A print control program for controlling a printing apparatus that prints an image by forming a plurality of types of dots having different dot sizes on a print medium, the print medium being loaded with the print medium based on predetermined image data Printing having a patch printing function for printing a patch for each dot type, and causing the computer to control the number of patches for each dot type in accordance with the dot size in the patch printing function Control program.

  According to the above print control program, the patch printing function can print the number of patches suitable for each dot size. Accordingly, the number of patches in the entire color chart can be reduced as compared with the conventional color chart in which the number of patches for each dot type is the same, and as a result, the color measurement time can be shortened. Furthermore, the amount of ink consumed for printing the color chart can be reduced.

The block diagram which shows schematic structure of a computer and a printer. The enlarged view of a nozzle and its internal structure. 1 is a schematic diagram of a system suitable for performing ID setting processing. FIG. The flowchart which showed the outline of the ID setting process which a computer performs. FIG. 3 is a diagram illustrating an example of a color chart according to the first embodiment. The flowchart which shows the detail of ID calculation processing. 6 is a flowchart illustrating processing for performing print control. The figure which shows an example of the color chart which concerns on 2nd Embodiment. The figure which shows an example of the color chart which concerns on 3rd Embodiment.

(First embodiment)
The print control apparatus according to the first embodiment will be described below with reference to the drawings.

<Schematic configuration of print control device>
First, a schematic configuration of a computer corresponding to the printing control apparatus according to the present embodiment and a printer as a printing apparatus controlled by the computer will be described.

FIG. 1 is a block diagram illustrating a schematic configuration of the computer 10 and the printer 20.
In the computer 10, the CPU 11 that is the center of the arithmetic processing controls the entire computer 10 via the system bus 10 a. Connected to the system bus 10a are a ROM 12, which is a non-rewritable semiconductor memory, a RAM 13, which is a rewritable semiconductor memory, various interfaces (I / F) 17a to 17c, a printer I / F 17d, a hard disk drive (HDDRV) 15, and the like. Has been. In addition, a hard disk (HD) 14 that is a magnetic disk is connected to the system bus 10a via an HDDRV15.

The HD 14 stores an operating system (OS), an application program (APL), a print control program for controlling the printer 20, and the like (not shown).
The HD 14 also includes an ID 14a as error information indicating the degree of color misregistration used for correcting color misregistration in the printer 20, a plurality of color correction data 14b, a dot allocation table 14c, selected color component data 14d, a standard A recording rate table TB and the like are stored. Details of the ID 14a, the color correction data 14b, the dot distribution table 14c, the selected color component data 14d, and the standard recording rate table TB will be described later.

  A display 18a that displays an image based on image data is connected to the I / F 17a. A keyboard 18b and a mouse 18c are connected to the I / F 17b as operation input devices.

The colorimeter 40 is connected to the I / F 17c (for example, USB I / F). The colorimeter 40 includes a color detection unit 40a. By directing the color detection unit 40a toward an object to be measured, the color measurement unit 40a has an L ^* a ^* b ^* color system defined by the International Commission on Illumination (CIE). The based color value L ^* a ^* b ^* can be input as a colorimetric value. The input colorimetric value can be output to the computer 10.
Here, the L ^* a ^* b ^* color space is a uniform color space that does not depend on the device. Note that the color space for color measurement in this embodiment may be a CIE-defined L ^* u ^* v ^* color space, a CIE-defined XYZ color space, an RGB color space, or the like. Further, color measurement of a color chart (an image in which a plurality of patches are collected) described later is not limited to the colorimeter 40, and a scanner or the like may be used.

  For example, the printer 20 is connected to the printer I / F 17d via a serial I / F cable. The print control program is executed when the APL print function is executed, and can perform bidirectional communication with the printer 20 via the printer I / F 17d. Then, the print control program receives image data from the APL via the OS, converts it into raster data, and sends it to the printer 20 as print data.

On the other hand, the printer 20 uses ink filled in each ink cartridge 28 corresponding to each color (in this embodiment, cyan (C), magenta (M), yellow (Y), and black (K)). A print image based on the print data is printed by forming dots by discharging from the print heads 29a to 29d and adhering to the print paper (print medium).
The type and number of inks used are not limited to those described above, and various inks such as light cyan, light magenta, light black, dark yellow, red, violet, and non-colored ink can be used. Various printers such as a bubble printer that generates bubbles in the ink passage and discharges the ink, and a laser printer that prints a print image on printing paper using toner ink can be employed. Furthermore, the ink used by the printer may be liquid or solid.

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

  The communication I / O 24 is connected to the printer I / F 17d in the computer 10. The printer 20 receives raster data for each color transmitted from the computer 10 via the communication I / O 24.

  The ASIC 26 outputs applied voltage data corresponding to raster data to the head drive unit 26a while transmitting and receiving a predetermined signal to and from the CPU 21. The head drive unit 26a generates an applied voltage pattern (drive waveform) to the piezo elements built in the print heads 29a to 29d from the applied voltage data, and ejects ink of each color from the print heads 29a to 29d 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. The ink cartridges 28 and the print head unit 29 are mounted on the carriage, and the ink cartridges 28 and the print head unit 29 reciprocate in the direction along the guide rail (main scanning direction). A paper feed mechanism 27b is connected to the I / F 27. The paper feeding mechanism 27b conveys the printing paper at a predetermined speed in a direction (sub scanning direction) substantially orthogonal to the main scanning direction by a paper feeding roller (not shown).

  Each of the print heads 29a to 29d is provided with a plurality of inkjet nozzles, and piezo elements are arranged corresponding to each of these nozzles. FIG. 2 is an enlarged view of the nozzle and its internal structure. As shown in the figure, 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 ink droplets Ip and is ejected from the tip of the nozzle Nz at a high speed and penetrates into the printing paper. Dots are formed and printing is performed.

  FIG. 2 shows a drive waveform V for forming a predetermined number of types of dots having different dot sizes (ink amount per dot; dot diameter may be used). The dots having different ink amounts are formed depending on whether or not the small waveforms v1 and v2 are generated in the predetermined period shown in FIG. 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 displayed. In the order of generation, the ink amount of the ejected dots increases stepwise.

  In the present embodiment, the printer 20 can generate three patterns of driving waveforms including the driving waveform V, and can form three types of large, medium, and small dots in each driving waveform by properly using small waveforms. . Therefore, each print head of the printer 20 ejects three types of large dots, medium dots, and small dots, for a total of nine types (large dots 1 to 3, medium dots 1 to 3, and small dots 1 to 3). Is possible. The raster data transmitted from the computer 10 to the printer 20 is added with identification information for identifying each dot type. When the printer 20 acquires raster data representing the dot type for each raster, the printer 20 forms a plurality of types of dots having different ink amounts on the printing paper in accordance with the raster data.

<ID setting process>
Next, the setting process of the ID 14a stored in the HD 14 in the computer 10 will be described.

  FIG. 3 is a schematic diagram of a system suitable for performing the ID setting process. As shown in the figure, a colorimeter 40 is connected to the computer 10, and a plurality of mass production printers 20b that are ID setting targets are sequentially connected to the computer 10. The computer 10 is connected to a reference printer 20a, a first comparison printer, and a second comparison printer as necessary. The reference printer 20a, the first comparison printer, and the second comparison printer are printers of the same type as the mass production printers 20b, and the configuration of the printer 20 shown in FIG. 1 is applied.

  The ID 14a is set for each mass production printer 20b in the manufacturing process of each mass production printer 20b, and is calculated using the color measurement result of each color chart A printed on each mass production printer 20b. The value calculated in this way is unique to each mass production printer 20b and represents the degree of deviation of the ink ejection amount with respect to the reference printer 20a.

  FIG. 4 is a flowchart showing an outline of the ID setting process executed by the computer 10. The processing shown in the figure is executed according to the above-described print control program.

  First, in step S200, the computer 10 specifies a selected color component. In this identification process, the reference printer 20a is connected to the computer 10 as shown in FIG. Then, the computer 10 controls the target reference printer 20a to print a color component selection patch in which the ink recording amount is changed in a plurality of stages on the printing paper. At this time, it is assumed that ink of a color corresponding to the print head is ejected from a predetermined print head of the reference printer 20a.

  The CPU 11 acquires predetermined patch image data representing a plurality of patches corresponding to a plurality of dot recording rates stored in advance in the HD 14, and temporarily stores it in the RAM 13. The patch image data is data in which a single color solid color patch is expressed in gradation by a number of pixels. The patch image data is subjected to predetermined halftone processing and rasterization processing, and the generated rasterized data is sent to the reference printer 20a, whereby a plurality of color component selection patches corresponding to the patch image data are obtained. Control is performed to cause the reference printer 20a to print.

In the reference printer 20a, for example, nine color component selection patches of 10% to 90%, in which the dot recording rate is changed in increments of 10%, are printed on the printing paper. Here, the dot recording rate is a ratio of the number of formed dots to the total number of pixels in a predetermined area on the printing paper, and is a kind of ink recording amount. Each color component selection patch is measured using the colorimeter 40, and the computer 10 inputs color measurement data of each color component selection patch from the colorimeter 40. Next, the computer 10 uses a plurality of color components L ^* a ^* constituting the color measurement data based on the color measurement data of each color component selection patch and the dot recording rate when each color component selection patch is printed ^. Among b ^*, the color component having the largest change with respect to the change in the dot recording rate is specified as the selected color component, and is stored in the HD 14 as the selected color component data 14d. The selected color component data 14d is used when calculating an ID (described later).

  In step S210, the standard dot recording rate is specified. The standard dot recording rate is a dot recording rate for printing each patch P1 (to be described later) constituting the color chart A, and can basically be ejected by each print head (ink type) and the print head. It is determined for each combination with a different dot type. Each standard dot recording rate is determined based on a guideline that the amount of change in colorimetric data due to variations in ink ejection amount is the largest dot recording rate.

Here, a method for specifying the standard dot recording rate will be described.
The computer 10 uses, for example, each of a large dot 1, a medium dot 1, and a small dot 1 from a single print head with respect to the first comparison printer, so that a dot recording rate (for example, 10%) in a plurality of stages. ˜90%), a control for printing a plurality of first comparison patches is performed. Similarly, for the second comparison printer, a plurality of second comparisons are performed from a single print head based on a plurality of dot recording rates using a large dot 1, a medium dot 1, and a small dot 1, respectively. Control to print the patch.
The first comparison printer is a machine body that ejects a larger amount of ink than the reference printer 20a in each print head. The second comparison printer is the same as the reference printer 20a in each print head. It is assumed that the machine has a smaller amount of ink to be ejected.

  Next, the computer 10 inputs colorimetric data obtained by colorimetry by the colorimeter 40 for each first comparison patch and each second comparison patch. Then, the computer 10 obtains the variation amount of the selected color component between the first comparison patch and the second comparison patch having the same dot type and dot recording rate for forming the patch.

  In general, the dot recording rate at which the variation amount of the selected color component is maximized becomes lower as the type of dot has a larger ink amount. Based on the transition of the variation amount of the selected color component for each dot type, the computer 10 identifies the dot recording rate at which the variation amount is the largest for each dot type, and these are designated as the first comparison patch and the second comparison patch. The standard dot recording rate for each dot type (in the above example, large dot 1, medium dot, and small dot) for the print head used for printing the patch for printing. Note that, for each combination of the remaining print heads and dot types, as described above, the variation amount of the selected color component is the largest using the print results of the first comparison printer and the second comparison printer. The dot recording rate is specified and used as the standard dot recording rate for each combination.

  As described above, in the present embodiment, even when the amount of ink ejected for each combination of the print head and the dot type corresponding to each ink type is slightly different, the standard dot in which the difference easily appears in the color measurement result. Find the recording rate. The computer 10 stores in the HD 14 a standard recording rate table TB that collectively describes the standard dot recording rates for each combination of the print head and the dot type specified as described above.

In step S220, the computer 10 controls the target mass production printer 20b to print the color chart A on the printing paper based on the standard dot recording rate. At this time, it is assumed that the corresponding types of ink (CMYK) are ejected from the print heads 29a to 29d of the mass production printer 20b that is the setting target of the ID 14a.
Note that the processing in step S220 corresponds to processing as a patch printing unit, a patch printing process, and a patch printing function.

  FIG. 5 is a diagram illustrating an example of the color chart A. As illustrated in FIG. As shown in the figure, the color chart A is configured by printing a plurality of patches P1 successively in each of the main scanning direction and the sub-scanning direction. Each patch P1 of the color chart A is a single color, and is printed with only one dot type using one print head. In FIG. 5, the first character of the name of each patch P1 indicates the ink type used for printing the patch P1, and the second and subsequent characters indicate the dot type. In addition, the numbers in parentheses under the name of each patch P1 indicate what number the patch P1 is printed with the same combination of ink type and dot type. That is, for the patch P1 with the same combination of ink type and dot type, the number in parentheses of the last printed patch P1 indicates the number of the same patch P1. For example, “C large dot (4)” indicates that the patch P1 is a large dot printed with C ink, and is printed last. It shows that four patches P1 exist in the combination of large C dots.

  In the case of the color chart A shown in FIG. 5, the patches P1 of CMYK color inks are arranged in the main scanning direction. In addition, a predetermined number of small, medium, and large dot types are arranged in the sub-scanning direction. Here, two small dots of each color ink are arranged in the sub-scanning direction, three medium dots of each color ink are arranged in the sub-scanning direction, and four large dots of each color ink are arranged in the sub-scanning direction. It is arranged one by one.

  When the patch P1 is arranged at only one position and printed for each combination of ink type and dot type, the ID is calculated using only the colorimetric result of this one patch P1, and the mass production printer 20b. It does not accurately represent the ink ejection performance. This is because the color measurement results differ because the printing position on the printing paper is different due to a mechanical error unique to each mass production printer 20b. On the other hand, in the present embodiment, as described above, a plurality of patches P1 having the same combination of ink type and dot type are arranged and printed at a plurality of positions on the printing paper. As a result, the ID is calculated using the colorimetric results of the patches P1 arranged at a plurality of positions, and the calculated ID value can more accurately represent the ink ejection performance of the mass production printer 20b.

  Further, in the present embodiment, for the patch P1 having the same combination of ink type and dot type, a larger number of patches P1 having a dot type smaller than a small number are arranged, and the number of patches P1 having a dot type larger than a medium. Many are arranged. That is, the smaller the dot size, the smaller the number of patches P1 to be printed. This is because the smaller the dot size on the printing paper, the less the influence of subtle mechanical errors unique to the mass production printer 20b when ejecting the dots.

  Thus, the overall colorimetric time for the color chart A can be shortened by controlling the number of patches P1 to be printed to be smaller as the dot size is smaller. Thereby, accuracy in calibration can be ensured and time required for calibration can be shortened. Furthermore, the amount of ink consumed for printing the color chart A can be reduced.

In step S <b ^> 230, the computer 10 measures the color of each patch P <b ^> 1 printed on the color chart A using the colorimeter 40, and inputs each colorimetric data (L ^* a ^* b ^* ) from the colorimeter 40. Then, the computer 10 stores the input colorimetric data of each patch P1 in the HD 14.

  In step S240, the computer 10 calculates an ID for each combination of ink type and dot type based on the input colorimetric data of each patch P1.

<ID calculation process>
FIG. 6 is a flowchart showing details of the ID calculation processing.
In step S241, the computer 10 selects the ID from all combinations of ink types and dot types (for example, when there are 4 types of ink and 3 types of dots, there are a total of 12 combinations). One combination to be calculated is determined.

  In step S242, the computer 10 acquires a selected color component from the color measurement data of the patch P1 related to the combination determined in step S241 from a predetermined storage area such as the HD14. For example, in the case of the combination of C ink and large dot 1, the selected color component of each patch P1 (C large dots (1) to (4)) is acquired.

  In step S243, the computer 10 calculates the average value of the selected color components of each patch P1 acquired in step S242. That is, the selected color component of each patch P1 is expected to have a different value because the printing position of the patch P1 is different from each other. By averaging these values, a mechanical error of the mass production printer 20b is obtained. It is possible to eliminate the influence of the difference in printing density caused by the above.

In step S244, the computer 10 calculates an ID based on the average value of the selected color components calculated in step S243. In the present embodiment, when the average value is D _ave , as an example, the average value is obtained by an expression of ID = int (α · D _ave + β). Here, int is a function that makes a numerical value with a decimal point an integer, and α and β are predetermined coefficients.

  In step S245, the computer 10 determines whether or not an ID has been calculated for all combinations of ink types and dot types. If there is a combination for which no ID has been calculated (step S245: NO), step 10245 is performed. Returning to S241, after updating the combination whose ID is to be calculated, the processing from step S242 is repeated. On the other hand, if the ID has been calculated for all the combinations (step S245: YES), the ID calculation process in FIG. 6 is terminated.

Returning to the flowchart of FIG. 4, in step S250, the computer 10 stores the calculated ID in the memory 31 of the print head unit 29 in the mass production printer 20b. As a result, the ID setting process for all combinations of the print heads 29a to 29d corresponding to each ink type and the dot type in the mass production printer 20b is completed. The generated ID includes only the selected color component specified as the color component having the greatest change with respect to the change in the ink recording amount from among the color components L ^* a ^* b ^{* in} the L ^* a ^* b ^* color space. This is error information calculated based on the size.

  In this embodiment, a plurality of mass production printers 20b are sequentially connected to the computer 10 and the ID setting process is performed for each mass production printer 20b. However, the processes in steps S200 and S210 in FIG. It is only necessary to perform the ID setting process once for the mass production printer 20b. In the ID setting process for the second and subsequent mass production printers 20b, the process may be started from step S220.

  The ID calculation method is not limited to the above-described calculation formula. For example, the ID may be calculated by comparing the average value with predetermined reference colorimetric data obtained in advance. Here, the reference color measurement data is a color measurement result of a patch that is preliminarily printed by the reference printer 20a by the computer 10 and used as a reference for color correction. In step S240, the average value obtained from the color measurement result of the color chart A and the reference color measurement data (selected color component of the reference color measurement data) are the same in ink type and dot type. In contrast, the ID is determined according to the magnitude of the difference. The ID determined in this way accurately represents the variation in the ink discharge amount of each mass production printer 20b with respect to the reference printer 20a.

<Print control processing>
FIG. 7 is a flowchart showing a process of correcting print data using the ID of the mass production printer 20b and performing print control based on the corrected print data. In the following, it is assumed that each of the print heads 29a to 29d of the mass production printer 20b to be subjected to print control is in a state of ejecting CMYK inks of the corresponding types.

  First, in step S305, the computer 10 determines whether or not an ID has been acquired from the mass production printer 20b. If the ID has already been acquired (step S305: YES), it is determined that it is not necessary to acquire the ID from the mass production printer 20b, and the process proceeds to step S320. On the other hand, if the ID has not been acquired (step S305: NO), the process proceeds to step S310.

  In step S310, the computer 10 creates an ID acquisition request and transmits it to the mass production printer 20b.

  In step S <b> 315, the mass production printer 20 b receives the acquisition request, reads out IDs corresponding to all combinations of ink colors and dot types from the memory 31 of the print head unit 29, and transmits them to the computer 10. The computer 10 acquires all IDs and stores them in the HD 14 as IDs 14a. As described above, since the ID is integrated with the mass production printer 20b, the user does not need to separately input an ID corresponding to the printer even if the printer to be used is changed.

In step S320, the computer 10 inputs image data made up of gradation data corresponding to a plurality of element colors for each of a plurality of pixels from a predetermined image input device, HD 14 or the like, and the image is input for each RGB. Conversion into RGB data in a wide RGB color space expressed by a plurality of pixels in gradation. At this time, data may be partially read, or only a pointer indicating a buffer area used for data transfer may be transferred.
Here, the input image data is data in which an image is expressed by gradation data for each of a large number of pixels in the form of a dot matrix, and image data composed of RGB defined in the sRGB color space, or YUV color specification. There are image data composed of YUV in the system. Since each component of the image data has various gradations, the image data is converted into RGB data of 256 gradations for each RGB in the wide RGB color space in accordance with the definition of sRGB or YUV color system. This RGB data is print data representing an image with a plurality of element colors RGB.

  In step S325, the computer 10 refers to the color conversion LUT while sequentially moving the target pixel using the gradation data of each pixel constituting the RGB data as a conversion target, and converts the RGB data into the usage amounts of the CMYK inks. Is converted into CMYK data composed of gradation data corresponding to the above.

  Here, the color conversion LUT is an information table that defines a correspondence relationship between the RGB data and the CMYK data in which the image is expressed by the same number of pixels for each CMYK with respect to a plurality of reference points. When CMYK data that matches the input RGB data is not stored in the color conversion LUT, CMYK data corresponding to a plurality of RGB data close to the input RGB data is acquired, and RGB data is obtained by interpolation such as volume interpolation. To CMYK data corresponding to The CMYK data is print data in which an image is expressed by gradation data for each of a plurality of pixels in a dot matrix like RGB data, and the usage amount of each ink ejected from the print heads 29a to 29d by the mass production printer 20b. It is assumed that the data is 256 gradation data for each of CMYK.

In step S330, the gradation data of each CMYK color constituting the CMYK data is obtained by referring to the dot allocation table 14c while sequentially moving the target pixel using the gradation data of each pixel constituting the CMYK data as a conversion target. A dot distribution process for converting (input gradation data) into dot amount data (output gradation data) represented by a plurality of dot types having different ink amounts is performed.
In this embodiment, color misregistration is compensated by correcting the dot amount data (print data) using the ID 14a. This dot distribution table 14c is an information table that defines the correspondence between input gradation data representing the amount of ink used in the mass production printer 20b and output gradation data representing the amount of dot formation for each type of dot. is there. The dot allocation table 14c is provided for each color, and stores output tone values representing the dot formation amount in each tone of the input tone values for each dot type.

  In step S335, the computer 10 sets the target ink color and dot type for correcting the dot amount data. For example, a different numerical value is associated with each combination of each ink color and each dot type, and the value of the pointer for storing this numerical value is sequentially updated. The combination of these may be set.

  In step S340, the computer 10 reads the ID 14a corresponding to the set combination of ink color and dot type from the HD 14, and the color correction data corresponding to the value of the ID 14a among the plurality of color correction data 14b stored in the HD 14. Identify and read.

  In step S345, the computer 10 reads out in step S340 while sequentially moving the target pixel using the gradation data of each pixel constituting the dot amount data corresponding to the set combination of ink color and dot type as the conversion target. By referring to the color correction data, the dot amount data of the target pixel is corrected, and corrected dot amount data is generated.

  In step S350, the computer 10 determines whether or not all combinations of each ink color and each dot type have been set. If not set (step S350: NO), steps S335 to S350 are repeated and set. If so (step S350: YES), the process proceeds to step S355.

  In step S355, the computer 10 performs predetermined halftone processing such as an error diffusion method, a dither method, and a density pattern method on the dot amount data for each dot size, and has the same number of pixels as the number of pixels of the CMYK data. Generate halftone data for each CMYK. The halftone data is data representing the dot formation status as the presence / absence of dot formation. For example, the gradation value “1” is binarized in correspondence with dot formation and the gradation value “0” is not dot formation. Two-level binary data can be obtained. Of course, it is good also as data of 4 gradations.

  In step S360, the computer 10 performs predetermined rasterization processing on the halftone data generated in step S355, rearranges them in the order used by the printer, and generates raster data for each CMYK.

  In step S365, the computer 10 outputs raster data to the mass production printer 20b. The mass production printer 20b obtains raster data representing an image, drives the print heads 29a to 29d on the basis of these data, ejects ink, adheres it to the print paper, and prints a print image corresponding to the RGB data. Form. Since the raster data is data in which color misregistration is compensated for each CMYK, the printed image is an image in which color misregistration is compensated.

(Second Embodiment)
Hereinafter, a print control apparatus according to the second embodiment will be described with reference to the drawings.

  The print control apparatus according to the second embodiment is different from the print control apparatus according to the first embodiment described above in the content of the color chart to be printed by the mass production printer 20b. The contents other than the contents of the color chart are the same as those of the print control apparatus according to the first embodiment.

  FIG. 8 is a diagram illustrating an example of a color chart B according to the second embodiment. In the color chart B shown in the figure, each patch P2 is a single color solid color and is printed with only one dot type using one print head, as in the color chart A according to the first embodiment. Has been. In FIG. 8, the name of each patch P2 is expressed in the same manner as each patch P1 in the color chart A.

  In the case of the color chart B, a plurality of patches P2 having the same combination of ink type and dot type are continuously arranged so as to be folded back from the main scanning direction to the sub scanning direction. In addition, the dot types of small, medium, and large are arranged so as to be continuous by a predetermined number. Here, 8 C small dots are continuously arranged, 12 C medium dots are continuously arranged, and 24 C large dots are continuously arranged. As described above, in the color chart B, as in the color chart A, the smaller the dot size, the smaller the number of patches P2 to be printed. Although not shown, the other ink colors are similarly arranged.

  In the color chart B of this embodiment, a plurality of patches P2 having the same combination of ink type and dot type are continuously arranged so as to be folded back from the main scanning direction to the sub scanning direction. Thereby, even when the speed at which the print head unit 29 reciprocates in the main scanning direction varies depending on each position in the main scanning direction, the average value of the color measurement data of each patch P2 continuous in the main scanning direction is calculated. As a result, it is possible to reduce the influence of uneven printing density in the main scanning direction.

(Third embodiment)
Hereinafter, a print control apparatus according to the third embodiment will be described with reference to the drawings.

  The print control apparatus according to the third embodiment is different from the print control apparatus according to the first embodiment described above in the content of the color chart to be printed by the mass production printer 20b. The contents other than the contents of the color chart are the same as those of the print control apparatus according to the first embodiment.

FIG. 9 is a diagram illustrating an example of a color chart C according to the third embodiment. The color chart C and the color chart A according to the first embodiment have different ink duty limit values when printing the respective color charts A and C. The ink duty limit value represents an upper limit value of the amount of ink that can be ejected in a unit area of the print medium.
In the present embodiment, an example in which the ink duty limit value in the color chart A is set to 70% when the ink duty limit value in the color chart A is set to 100% is shown. Further, in the color chart C, as in the color chart A according to the first embodiment, each patch P3 is a single color, and is printed with only one dot type using one print head. Yes. In FIG. 9, the name of each patch P3 is expressed in the same manner as each patch P1 in the color chart A.

  In the case of the color chart C, similarly to the color chart A, the patches P3 of CMYK color inks are arranged in the main scanning direction. In addition, a predetermined number of small, medium, and large dot types are arranged in the sub-scanning direction. Here, three small dots of each color ink are arranged in the sub-scanning direction, five medium dots of each color ink are arranged in the sub-scanning direction, and seven large dots of each color ink are arranged in the sub-scanning direction. It is arranged one by one. As described above, in the color chart C, as in the color chart A, the smaller the dot size, the smaller the number of patches P2 to be printed.

  Further, the ink duty limit value in the color chart C is 70%, which is lower than 100% of the ink duty limit value in the color chart A. Therefore, in the case of the color chart C, the number of patches P3 to be printed is larger for the patch P3 having the same combination of ink type and dot type than in the case of the color chart A. That is, the lower the ink duty limit value, the larger the number of patches P3 to be printed.

  In the color chart C of the present embodiment, when the background of the patch P3 is easily visible due to the low ink duty limit value, the influence of the background is measured in the color measurement of the patch P3 by increasing the number of patches P3 to be printed. It is possible to cope with a colorimetric error that is received, and to ensure accuracy in calibration.

  DESCRIPTION OF SYMBOLS 10 ... Computer, 10a ... System bus, 11 ... CPU, 12 ... ROM, 13 ... RAM, 14 ... HD, 14a ... ID, 14b ... Color correction data, 14c ... Dot allocation table, 14d ... Selected color component data, 15 ... HDDRV, 17a, 17b, 17c ... I / F, 17d ... Printer I / F, 18a ... Display, 18b ... Keyboard, 18c ... Mouse, 20 ... Printer, 20a ... Standard printer, 20b ... Mass production printer, 21 ... CPU, 22 ... ROM, 23 ... RAM, 24 ... communication I / O, 25 ... control IC, 25b ... ink path, 26 ... ASIC, 26a ... head drive, 27 ... I / F, 27a ... carriage mechanism, 27b ... paper feed Mechanism: 28 ... Ink cartridge, 28a ... Memory chip, 29 ... Print head unit, 2 A～29d ... print head, 31 ... memory, 32 ... bus, 40 ... colorimeter, 40a ... color detection unit, A, B, C ... color chart, P1, P2, P3 ... patch.

Claims (4)

A printing control device that controls a printing device that prints an image by forming a plurality of types of dots having different dot sizes on a printing medium,
A patch printing unit that prints a patch for each dot type on the print medium based on predetermined image data;
The print control apparatus, wherein the patch printing unit performs control so that the number of patches decreases as the dot size decreases . When the upper limit of the amount of ink that can be discharged in the unit area of the print medium is the ink duty limit value,
The print control apparatus according to claim 1 , wherein the patch printing unit performs control so that the number of patches increases as the ink duty limit value decreases. A printing control method for controlling a printing apparatus that prints an image by forming a plurality of types of dots having different dot sizes on a printing medium,
A patch printing step of printing a patch for each dot type on the print medium based on predetermined image data;
In the patch printing step, control is performed such that the number of patches decreases as the dot size decreases . A print control program for controlling a printing apparatus that prints an image by forming a plurality of types of dots having different dot sizes on a print medium,
Based on predetermined image data, it has a patch printing function for printing a patch for each dot type on the printing medium,
In the patch printing function, a printing control program causing a computer to perform control so that the number of patches decreases as the dot size decreases .

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