JP4572354B2 - Color image data correction apparatus, color image data correction method, and color image data correction program - Google Patents

Description

The present invention relates to a color image data correction device, a color image data correction method, and a color image data correction program .

  In a color printer such as an inkjet printer, a color image is printed with three color inks of cyan (C), magenta (M), and yellow (Y), or four color inks in which black (K) is added thereto. To do.

By the way, the color image to be printed has the original intended color because the print head uses the color ink in the expected amount. descend.
For this reason, in the conventional color printer shown in Patent Document 1, the drive signal can be adjusted for each drive circuit that drives the print head, and the use amount of the color ink can be adjusted by setting the drive signal in a factory or the like. It has become.
Japanese Patent Publication No. 6-79853

In the conventional apparatus described above, the color misregistration is eliminated by performing factory adjustment for each color printer. However, when the color misregistration occurs due to aging or environmental change, the color misregistration cannot be adjusted.
The present invention has been made in view of the above problems, and is a color image data correction device and color image data capable of eliminating color misregistration corresponding to machine differences without depending on hardware. An object of the present invention is to provide a data correction method and a color image data correction program .

In order to achieve the above object, the invention according to claim 1 is characterized in that the predetermined element is based on multi-tone color image data obtained by color-separating a plurality of pixels in a dot matrix of a color image for each predetermined element color. A color image data correction device that corrects color misregistration in a printer by changing the color image data to a printer that prints the same color image by attaching a dot-shaped recording material for each color on a print medium. Te, the measured color data obtaining means for obtaining actual color data obtained by measuring the printed result of a predetermined images data including a plurality tone printed by the printer, is the standard print result of the predetermined image data Standard color data acquisition means for acquiring standard color data, and a color correction table for changing the color image data based on the correspondence between the measured color data and the standard color data Comprising a table creation means for creating, and the predetermined image data, the amount of change in color measurement result with respect to the change of the gradation value is compared with the outside the gray scale region by a predetermined change amount larger tone area A plurality of gradation values set at non-constant gradation intervals so as to be dense , and the measured color data acquisition means performs colorimetry on a print result of the printer at the plurality of gradation values It is as.

In the invention according to claim 1 configured as described above, the actually measured color data acquisition means is outside the gradation area in the gradation area where the change amount of the color measurement result with respect to the change of the gradation value is larger than the predetermined change amount. When the measured color data is obtained by measuring the print result obtained by printing the predetermined image data including a plurality of gradation values set at non-constant gradation intervals so as to be denser than the above, and obtaining the measured color data, the standard The color data acquisition means acquires color measurement data for the standard print result of the image data of the predetermined multiple gradation values as standard color data, and the table creation means is based on the correspondence between the actually measured color data and the standard color data. Color correction that calculates a correction correspondence for changing the color image data so as to obtain a print result of the standard color intended by the color image data, and changes the color image data based on the correspondence To form a Buru.

Color printers, dot-like recording medium the print medium on every iodine color based color images to grayscale color image data color separation of each pixel decomposed in a dot matrix of pixels to a predetermined element color Assuming that the same color image is printed by attaching it to the printer, a color correction table as described above is created by a computer, and the color image data is changed using the same color correction table. The color shift in is corrected.

The reason is as follows. First, while the measured color data to the printing result when the printer makes a print based on the image picture data of a predetermined multiple number tone value is measured, colorimetric data standard for the original standard print results It is acquired separately as color data. If these tone values match, if the tone values match, the desired color is reproduced and color correction is not necessary, but when the tone values are shifted, a desired print result is obtained. Even if the color image data generated as described above is output, a desired print result cannot be obtained. However, the correspondence between the gradation value of the standard color data that matches the measured color data and the gradation value measured by the measured color data acquisition means (hereinafter referred to as the colorimetric gradation value) is known. If so, by changing the color image data in advance so as to obtain the print result of the standard color intended by the color image data, the print result matches the standard color intended by the color image data.

As described above, the color correction table for changing the color image data based on the correspondence relationship between the actually measured color data and the standard color data has an inverse function, but there are various specific methods. As an example, the upper table creation means uses the correspondence between the gradation value of the standard color data that matches the measured color data and the gradation value for colorimetry as a parameter of a higher-order interpolation formula, the correction gradation value given in order to obtain the standard color tone values is calculated from the interpolation formula may be configured to perform association.

In this configuration , a desired gradation value is obtained by using the correspondence relationship between the gradation value of the standard color data that matches the actually measured color data and the gradation value for colorimetry as a parameter of a higher-order interpolation formula. The corrected gradation value given to obtain the standard color is calculated from the interpolation formula. For example, if utilizing the interpolation equation to Lagrange interpolation equation, the tone value of the standard color data and the color measurement gradation value matching the measured color data as a parameter, any actual measurement color data The gradation value to be given to obtain can be obtained.

As an example of another specific method for creating the color correction table, the table creation means may include a difference between a gradation value of standard color data that matches the measured color data and the gradation value for colorimetry. Based on this, a correction relationship that minimizes the overall error in an arbitrary gradation value is obtained, and a corrected gradation value that is given to obtain a desired standard color is obtained based on this correction relationship, and correlation is performed. It is good also as a structure.

In this configuration , the correction relationship in which the error in an arbitrary gradation value is totally minimized based on the difference between the gradation value of the standard color data that matches the measured color data and the gradation value for colorimetry. Ask for. For example, if determining the correction relationships using the least squares approximation equation, correcting relationship Sadamari very easy to obtain the color gradation value measurement should give to obtain any actual color data, and this Even if it is obtained simply as described above, it can be said that the total value of errors in all gradation values is the smallest when viewed comprehensively.

By the way, even if the amount of color ink used is correct, the physical property of the amount of color ink absorbed differs depending on the printing medium, and is influenced by it. For example, specifically, with a print medium in which color ink penetrates into the interior, such as paper, and a print medium in which color ink spreads on the surface with little penetration into the interior, such as an OHP film, The amount of correction for the error in the amount of color ink used varies slightly. Since the amount of correction is related to the amount of color ink used, it can be corrected by applying a certain coefficient.
For this reason, the table creation means has medium selection means for acquiring print medium selection information, and uses, as a parameter, the degree to which the print result changes from the standard color due to the difference in the print result due to the physical characteristics of the print medium. And it is good also as a structure reflected on the said correction | amendment correspondence based on the selection information of the printing medium acquired at the same time.

In this configuration , the elimination of the deviation in the amount of color ink used and the elimination of the influence on the printing result due to the physical characteristics of the printing medium are grasped as the same level concept, and the printing medium selection information is obtained by the medium selection means . Once acquired, the degree to which the print result changes from the standard color due to the difference in the print result due to the physical characteristics of the print medium is used as a parameter and reflected in the correction correspondence based on the acquired print medium selection information. .
That is, when a print medium is selected, correction is performed using parameters corresponding to physical characteristics such as the amount of color ink absorbed in the print medium. In the case of a print medium that tends to spread on the surface, the dot area on the print medium is reduced just by performing a minus correction in advance, which is improved. Of course, the reverse is also true.

If there are a large number of colorimetric gradation values, the correction can be made accurately, but the work for obtaining the measured color data is complicated and complicated. If the colorimetric gradation values are small, the correction cannot be performed accurately. However, the correction accuracy can be improved by suppressing the point even if the colorimetric gradation value is small.
As an example, the upper Symbol measured color data acquiring means and the standard color data acquisition means, as the plurality of color measurement tone values, the amount of change in color measurement result to the data change is large, and the obtained measured color data It is also possible to employ a configuration in which the setting is densely performed in a region where the quantization error based on the above does not increase.

  For example, if the change amount of the measured color data is constant in a certain gradation range, it is useless to obtain a plurality of colorimetric gradation values during that period. In other words, it can be said that it is desirable to select the colorimetric gradation value where the change in the colorimetric result is large relative to the amount of change in the colorimetric gradation value, but there is a slight error when the change is too large. There is also an adverse effect that is greatly reflected. In this way, even if it seems to be relatively standing, its harmony point is obtained, so the amount of change in the colorimetric result with respect to the data change is large, and the quantization error based on the acquired measured color data does not increase The gradation values for colorimetry are set densely.

By the way, the actually measured color data is measured by a colorimeter or the like, but this colorimeter may not be correct. Then, it is complicated to adjust the colorimeter each time, and there is a case where it is not known whether or not there is a deviation.
Therefore, the upper Symbol measured color data acquiring means and the standard color data acquisition means, together with the colorimetric data for the printed result to get the colorimetric data of the non-printed portion of the print medium, said table creation means, unprinted A configuration may be provided that includes actual color data correction means that corrects the deviation of the actual color data from the difference between the standard color data and the actual color data in the portion.

In this configuration , the measured color data acquisition unit and the standard color data acquisition unit acquire the color measurement data of the non-printed portion of the print medium together with the color measurement data for the print result. Originally, the measured color data of the non-printed part should be meaningless, but this corresponds to the fact that the colorimeter inherently reads the background color of the print medium itself, and is a standard measurement for the background color of the print medium. By comparing with the color data, it is possible to determine the presence or absence of a color shift in the colorimeter.

Under such a premise, the table creation means corrects the deviation of the measured color data itself by the measured color data correction means based on the difference between the standard color data and the measured color data in the non-printed portion.
Taking an inkjet printer as an example, a plurality of print modes can be selected using the same print head. An example is print resolution. When changing the resolution, the dot size may change, but the weight ratio and the area ratio are not directly proportional, so if you change the weight of the dots uniformly, color reproducibility will be improved. Naturally, changes will occur. That is, if you are a function that can change the print environment to the printer itself, deviation in each will be generated separately.

For this reason, the table creation means has print environment information acquisition means for acquiring, as a parameter, information on a print environment that affects a preset print result, and the printing based on the acquired parameter of the print environment information. It may be configured to calculate a correction correspondence relationship that can obtain a printing result of the standard color intended by the color image data while eliminating the influence on the result.

In this configuration , printing environment information that affects the printing result preset by the printing environment information acquisition unit is acquired as a parameter, and the influence on the printing result based on the acquired parameter of the printing environment information. The correction correspondence relationship for obtaining the print result of the standard color intended by the color image data is calculated while eliminating the above.
There are various specific methods for acquiring the measured color data. It may be acquired by communication, acquired by a data recording medium, or input from a keyboard. Further, in obtaining the actually measured color data, a step of outputting a printed matter may be included.

As an example, the upper Symbol measured color data acquisition means, the upper Kipu and patch print control means allowed to print the printed material of the color measurement tone values for printers, actually measured the actual measurement on the basis of the printed patches It is good also as a structure which has a data acquisition means which acquires color data.

In this configuration , the patch print control means causes the printer to print the colorimetric gradation value printed matter, and obtains the actually measured color data measured based on the patch printed by the data obtaining means . To do.
That is, it includes a series of processes from patch printing to actual color data acquisition.
When controlling the printing of patches, only the patches that are truly necessary are printed. In this case, a patch may be required for each of a plurality of printing environments. As an example, the upper Symbol patch printing unit, the patch at a plurality of printing environments that affect the print result may be configured to be printed on a single print medium.

In this configuration , patches in a plurality of printing environments are printed on a single print medium. In general, changing the printing environment also changes the printing medium, but printing on a single printing medium saves paper and improves workability.
Needless to say, the color image data correction apparatus as described above includes various modes such as being implemented in another apparatus or implemented together with another method. The present invention also provides a system including the above-described color image data correction device, a control method having steps corresponding to the configuration of the above-described device, a program for causing a computer to realize a function corresponding to the above-described device configuration, and the program recorded therein. It can also be realized as a computer-readable recording medium. The inventions of the system, the color image data correction method, the color image data correction program, and the medium on which the program is recorded also have the above-described operations and effects. Of course, the structure described in claim 2 can also be applied to the system, the method, the program, and the recording medium. The medium on which the program is recorded 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. In addition, even when the communication method is used as a supply method, the present invention is not changed.

The present invention as above mentioned can be realized as various embodiments, as an example, multi-gradation color image color separation of each pixel obtained by decomposing the color image in a dot matrix of pixels to a predetermined element color In order to output color image data for printing with a low gradation value required by a color printer that inputs data, attaches a dot-shaped recording material of a predetermined element color onto a print medium, and prints the same color image, A printing color for converting the color image data into the printing color image data by a computer using a color conversion table in which differences in element colors are associated between the color image data and the printing color image data An actual color measurement acquisition step for acquiring actual color measurement data for a print result based on color image data of a plurality of predetermined color measurement gradation values, and a medium on which an image data output program is recorded, and a standard The standard color data acquisition step for acquiring colorimetric data for the printing result, and the print result of the standard color intended by the color image data based on the correspondence relationship between the measured color data and the standard color data. A color correction correspondence calculating step for calculating a correction correspondence for changing the color image data, a table creating step for forming a color correction table for changing the color image data based on the correspondence, and the created it may be configured to and a color correction step of color correction to the printing color image data by superimposing applying a color correction table and the color conversion table from the color image data.

  In this example, the input color image data is multi-gradation data in which each pixel obtained by separating the color image into dot matrix pixels is color-separated into predetermined element colors, and dot-shaped recording of predetermined element colors is performed. When a color printer that prints the same color image by attaching a material to a print medium needs to be color image data for printing with a low gradation value, the color image data is used for the color image data for printing. The present invention is applied to a printing color image data output program for conversion to.

  Here, in the printing color image data output program, the actual colorimetric data for the print result based on the color image data of a plurality of predetermined colorimetric gradation values is acquired in the actual color data acquisition step, and the standard When the color measurement data for the standard print result is acquired in the color data acquisition step, the color correction correspondence calculation step calculates the standard color intended by the color image data based on the correspondence between the actually measured color data and the standard color data. In order to calculate a correction correspondence for changing the color image data so as to obtain a print result, the table creation step forms a color correction table for changing the color image data based on the correspondence, and this creation The color correction step is performed by superimposing the color correction table and the color conversion table on the color image data for printing. Color correction to the data.

That is, in addition to the normal conversion from color image data to printing color image data, the calculated correction correspondence is superimposed and applied. In this case, since the color correction table and the color conversion table need only be substantially superimposed, the application order is not particularly limited, and the tables may be applied separately or once the tables are joined. It may be applied to the method.
Of course, it is also possible to realize a printing apparatus including such a function, the input multi-gradation color image data color separation pixels that degrade color image in a dot matrix of pixels to a predetermined element color Color image data acquisition means, color printing means for printing the same color image by attaching a dot-shaped recording material on a print medium based on color image data for printing of low gradation values of predetermined element colors, Color conversion means for eliminating a difference in element colors between the color image data and the color image data for printing, and a difference in gradation values between the color image data and the color image data for printing are eliminated. Gradation converting means, colorimetric patch printing means for printing patches based on color image data of a plurality of predetermined colorimetric gradation values, and actual colorimetric data is acquired based on the printed patches. Patch colorimetric data acquisition A standard color data acquisition means for acquiring color measurement data for a standard print result based on the color image data, and a standard color intended by the color image data based on a correspondence relationship between the actually measured color data and the standard color data. Color correction correspondence calculating means for calculating a correction correspondence for changing the color image data so as to obtain a print result, and converting the correspondence from the color image data to the printing color image data. It is good also as a structure which comprises the color correction means to reflect.

Oite to the structure, type normal, multi-gradation color image data color separation of each pixel to decompose color image in a dot matrix of pixels by the color image data acquisition means to a predetermined element color, The color printing unit prints the same color image by attaching a dot-shaped recording material on the print medium based on the color image data for printing of a predetermined gradation color of a predetermined element color. Here, the color conversion unit eliminates the difference in element color between the color image data and the printing color image data, and the gradation conversion unit converts the color image data between the color image data and the printing color image data. Eliminate differences in tone values. On the other hand, the colorimetric patch printing unit prints a patch based on the color image data of a plurality of predetermined colorimetric gradation values, and the patch colorimetric data acquisition unit performs actual measurement based on the printed patch. When the color data is acquired, the standard color data acquisition unit acquires the color measurement data for the standard print result, so that the color correction correspondence calculating unit calculates the color image based on the correspondence between the actually measured color data and the standard color data. A correction correspondence for changing the color image data is calculated so that a print result of the standard color intended by the data can be obtained, and the color correction means converts the correspondence from the color image data to the printing color image data. Will be reflected in the conversion.

As described above, the present invention eliminates color misregistration corresponding to machine differences without depending on hardware by obtaining measured color data obtained by measuring the print result and performing predetermined calculations. Therefore, it is possible to provide a medium in which a color correction table creation program capable of creating a color correction table that can be used for recording is recorded. In addition, the accuracy can be improved while reducing the colorimetric gradation values.
According to the second aspect of the invention, the accuracy of color misregistration correction can be increased while reducing the colorimetric gradation values .

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a schematic flow of a color correction table creation program according to an embodiment of the present invention, and this color correction table creation program constitutes a part of a printing system. The printing system includes a personal computer main body (hereinafter referred to as a personal computer) and a printer. First, the configuration of the personal computer and the printer will be described.

FIG. 2 shows a schematic configuration of a typical personal computer 10.
The personal computer 10 includes a CPU 11 that is the center of arithmetic processing, and a secondary cache 13, a data bus unit 14, and a system controller 15 are connected to the CPU 11 via a CPU bus 12. In recent personal computers, the clock speed of the CPU bus 12 is increased in order to improve processing efficiency, and the slow memory 16 is accessed by the CPU 11 via the data bus unit 14 and the system controller 15. The memory 16 includes a RAM area as well as a ROM area such as a BIOS area.

  Similarly, the interfaces cannot be directly connected to the fast CPU bus 12, and a PCI bus 17, which is a general-purpose high-speed bus, is provided by the data bus unit 14 and the system controller 15. A common interface 18 for connecting a floppy disk is connected to the PCI bus 17 together with a communication interface such as a PS / 2 port, a parallel port, and a serial port that the personal computer 10 has directly, and high speed is particularly required. A bus master 19 is also connected for DMA transfer by connecting a hard disk or CD-ROM.

In addition to being able to connect the PCI device 21 directly to the PCI bus, an ISA bus 23, which is an old general-purpose bus with a narrow data width, is provided via an ISA bridge 22, and the ISA device 24 is connected via the ISA bus 23. It can be connected.
FIG. 3 shows peripheral devices for the personal computer 10. The keyboard 25 and mouse 26 are connected to the common interface 18 via the PS / 2 port, the printer 27 via the parallel port, and the modem 28 via the serial port. It is connected. The scanner 29 is connected to the PCI bus 17 via a SCSI card 21a as a PCI device 21. Various external devices can be connected to the SCSI card 21a, and a magneto-optical storage device 32 or the like is connected thereto. be able to. The display 31 is connected via the display controller card 21 b, and the hard disk 19 a and the CD-ROM drive 19 b are connected to the PCI bus 17 via the bus master 19.

Various devices are provided as the ISA device 24. However, if the PCMCIA card 24a is used, the PCMCIA card socket 33 can be connected, and the memory card 34 on which image data is recorded can be attached to easily input / output data. Become. The memory card 34 is a digital still camera 35, and it is easy to input data from other mobile personal computers.
In addition to these, the personal computer 10 can be connected to an external display via a video card, connected to a network via a LAN card, or connected to other external devices via an infrared communication device. It is also possible to do.

  The above is the schematic configuration of the hardware of the personal computer system. On the premise of such hardware, software is executed on the personal computer 10 in the form shown in FIG. That is, the BIOS 42 is executed based on the hardware 41, and the operating system 43 and the application 44 are executed in the upper layer. Basically, the operating system 43 accesses the hardware 41 via the BIOS 42 or directly, and the application 44 exchanges data with the hardware 41 via the operating system 43. For example, in order to read data from the hard disk 19 a, the hardware 41 is accessed via the operating system 43. In addition, various drivers for controlling the hardware 41 can be incorporated into the operating system 43, and the incorporated drivers become a part of the operating system 43 and execute various controls. Examples of drivers include a display driver that controls display on an external display via a video card, and a printer driver that executes print control on the printer 27.

On the other hand, the schematic configuration of the printer is shown in FIG. 5, and the configuration of the print head and the ink ejection principle are shown in FIGS. The printer 50 is a color ink jet printer, and is connected to the parallel port of the personal computer 10 in the same manner as the printer 27 described above.
The printer 50 is provided with a parallel interface 51 for connecting to the parallel port of the personal computer 10 and performs transmission and reception of commands and print data by parallel communication. The parallel communication is an interface capable of executing bidirectional communication such as a centronics method of unidirectional communication, nibble, ECB, and EPP. The parallel interface 51 is connected to the gate array 52, and is connected to the bus 54 via the gate array 52. A system ROM 56, a character generation ROM 57, and a D-RAM 58 are connected to the bus 54 together with the CPU 55. The CPU 55 executes a printer control program written in the system ROM 56 while using the D-RAM 58 as a work area and a buffer. Printing is performed using font data written in the character generation ROM 57.

A specific printing mechanism is electrically controlled through a gate array 52, and a paper feed motor is moved while a print head unit 61 is reciprocated (main scanning) by a carriage motor 59 with respect to printing paper. By feeding the printing paper (sub-scanning) 62, printing can be performed on almost the entire surface of the printing paper.
The print head unit 61 is composed of three print heads 61a. Each print head 61a has a fine pipe 61a3 extending from the color ink tank 61a1 to the nozzle 61a2, and an end portion of the pipe 61a3. Is formed with an ink chamber 61a4. A wall surface of the ink chamber 61a4 is formed of a flexible material, and a piezoelectric element 61a5 that is an electrostrictive element is provided on the wall surface. The piezo element 61a5 has a crystal structure distorted by applying a voltage and performs high-speed electro-mechanical energy conversion. As shown in FIG. 7, the distorted crystal structure distorts the wall surface of the ink chamber 61a4. Press to reduce the volume of the ink chamber 61a4. Then, a predetermined amount of color ink particles are ejected vigorously from the nozzle 61a2 communicating with the ink chamber 61a4. This pump structure is called a micro pump mechanism.

  In addition, two independent nozzles 61a2 are formed in one print head 61a, and color ink is independently supplied to the nozzles 61a2 in each column. Accordingly, the three print heads 61a each have two rows of nozzles, and it is possible to use six color inks to the maximum. In one example, two rows in the left printhead unit are used for black ink, only one row in the middle printhead unit is used for cyan ink, and two left and right rows in the right printhead unit are used. Can be used for magenta color ink and yellow color ink, respectively, and four color inks can be used, and if six color inks are used, the left column in the print head unit in the left column The right column is used for cyan ink, the right column is used for light magenta color ink while the right column is used for magenta ink while the right column is used for cyan ink, and the right column is used for black ink. In this case, the left column is used for light cyan ink while the right column is used for yellow ink.

In addition to these, the gate array 52 to which the print head unit 61 is connected is provided with a timer counter 63 that generates a clock used by the system, a nonvolatile EEPROM 64 that stores settings, and an operation panel 65.
By connecting the personal computer 10 and the printer 50 with the parallel connection cable 70, a schematic flow when the printing process is executed from the application 44 on the personal computer 10 is as shown in FIG.

  First, when color measurement data for a patch, which will be described later, is read in the actual measurement color data acquisition process of step 110, standard color measurement data for each patch is read in advance in step 120, and in step 130, the degree of coincidence between the two. Calculation is performed based on the degree of deviation, and a correspondence relationship for correcting the print data side in advance so that standard color reproduction is possible is calculated, and a color correction table that can easily use this correspondence relationship in step 140 is created. become. FIG. 8 shows a schematic flowchart rewritten for easy incorporation into the printer driver based on such a procedure, and FIG. 9 shows a correspondence relationship between processing and files. Hereinafter, each process will be described in more detail with reference to the flowchart.

First, printing is started by printing a patch to be measured. This is performed by the patch printing control process 200 shown in FIG.
In this printer driver, the printing mode and the number M0 of printing modes are acquired in step 202 to perform patch printing in each printing mode corresponding to the printer 50 having a plurality of printing modes. Specifically, it corresponds to a change in resolution, and according to the printer 50 corresponding to each mode of 720 DPI and 1440 DPI, a patch is printed at the same size and the same size for each mode. Become. The print mode itself may be acquired through parallel communication with the printer 50, or print mode data corresponding to a plurality of printers may be prepared in advance, and corresponding data may be read. The data to be read may be at least command data for setting a mode for the printer 50 and resolution information.

  Next, in step 204, “1” is set to a variable i as a loop counter, and in step 206, a paper feed command is issued and loop processing for repeating each mode is executed. A paper feed command is generated only once before each mode is repeated. As a result, only one sheet is replenished as shown in FIG. 11, and patches are printed repeatedly for each print mode. Become. In this example, it is assumed that only one sheet of paper is supplied because there are few print modes, but it is not necessary to supply different paper for each print mode. When the number of groups is large, a plurality of sheets can be used.

  In a loop process performed for each print mode, an i-th print mode setting command is generated in step 208 to instruct the printer 50 to change the print mode. The print mode setting command corresponds to the previously read command data, and in step 210, color patch print data corresponding to the resolution is transmitted. Since this printer 50 supports 720 DPI and 1440 DPI, the former is 720 × 1 ÷ 2.5 = 288 dot square in order to print a 1 cm square patch, and the latter is 1440 × 1 ÷ 2.5. = 576 dot angles. Since the color patch print data designates color ink in units of dots, the constituent dots are sent as corresponding to the difference in resolution.

  By the way, the color patches are a plurality of patches having a size of about 1 cm square as shown in FIG. 11, and printing is performed by changing the color for each patch. Of course, one patch uses only one color ink, and prints with different gradation values for each color ink. For example, printing is performed in order from low gradation (dark) to high gradation (light) using cyan ink, and the order is magenta ink, yellow ink, and black ink. Inkjet printers usually have two gradations, ie, whether or not to add dots, and in order to reproduce a high gradation value, halftone processing is performed by adjusting the number of dots applied per unit area.

In order to print in order from the low gradation (thin) to the high gradation (dark) as described above, it is possible or normal to print patches at a predetermined gradation interval in advance. However, in the present embodiment, the gradation value is determined by the following method.
First, FIG. 12 shows colorimetric data values as so-called tristimulus values (XYZ values) when all 256 gradations are printed using cyan ink. On the other hand, FIG. 13 shows how much the XYZ value changes every time one gradation value changes. As can be seen from FIG. 13, the XYZ value greatly changes due to the change of one gradation value up to the vicinity of the gradation value “50”. However, when the gradation value exceeds “50”, the amount of change becomes extremely small. That is. From such a relationship, if the gradation value exceeds “50”, the change amount is almost proportional to the gradation value regardless of which gradation value is selected. However, such a proportional relationship is maintained up to the vicinity of the gradation value “50”. I understand that there is no. Even if a large number of gradation values are selected with high gradation values, the correspondence relationship between the actually measured color data and the standard color data obtained therefrom is only a certain proportional relationship. On the other hand, if only a small number of gradation values are selected on the low gradation value side, errors are likely to occur in determining the correspondence between the measured color data and the standard color data.

However, if the XYZ value changes too much every time one gradation value changes, the error included in the measurement becomes large, resulting in a so-called quantization error as shown in FIG. Therefore, the interval for selecting the gradation value is widened again in an extremely low gradation region where the quantization error increases.
Based on the above policy, the interval is broadened in the region of extremely low gradation, and the interval is narrowed after this, and the interval is set wider from the middle gradation to the high gradation. Although it is not always necessary to select a uniform gradation value for each color ink, generally the same tendency is seen, so in this embodiment, a gradation value common to each color is selected. In the following, they are displayed as dg [1] to dg [n].

  In step 210, the color patch is printed for each print mode, and in step 212, the value of the loop counter is incremented by one. In step 214, the loop counter is compared with the print mode number M0 to determine whether all print modes have been completed. If all print modes have been completed, a paper discharge command is sent to the printer 50 in step 216, the printed color patch is discharged, and this patch print control process is ended.

Returning to FIG. 8, when the patch printing is finished, in step 300, colorimetry is waited. Colorimetry is a process of measuring each patch of a color patch with a colorimeter, and this is an operation performed by an operator without the help of this program.
The colorimeter needs to output colorimetric data in steps 500 and 600. FIG. 15 shows the processing flow in the colorimeter and FIG. 16 shows the data structure to be output.

When measuring with a colorimeter, color coordinates are first selected at step 302. Normally, an XYZ value or a Lab coordinate system is selected, but in the following description, it is assumed that the data is output in the CMY coordinate system so that the description does not go round.
If it is determined in step 304 that color measurement is to be started, it is determined in step 306 whether or not a new measurement is to be performed. If it is new, “0” is set to a variable i as a data counter in step 308. The read colorimetric value is substituted into the array variable DT [i], and thereafter, in step 310, the value of the variable i is incremented by “1”. Therefore, if “0” is set to the variable i as the data counter, it is overwritten regardless of the existing value.

Color measurement is performed by operating a color measurement switch (not shown), which generates a trigger. That is, a trigger is generated when the operator operates the switch to perform color measurement. Internally, the colorimetric value obtained by waiting for this trigger in step 312 is the i-th array variable DT [ i].
At this time, since the colorimeter itself performs measurement by a fixed sensor, the color space is fixed as XYZ, and is converted into a Lab coordinate system or the like according to the selected color coordinate space and output. . In the present embodiment, for the sake of simplification of explanation, for the time being, it becomes a CMY coordinate system value and is assigned to the array variable DT [i].

As long as the color patch remains, it is determined in step 316 that the color patch is added, and step 310 and the subsequent steps are repeated. That is, the colorimetric value is substituted into the array variable DT [i] while increasing the value of the variable i by “1”.
When all the color patches are measured, the current data counter value is substituted into the variable DTn in step 318, so that the variable DTn represents the number of colorimetric data.

  On the other hand, when the color measurement is completed, it is determined whether or not data transmission is performed in step 320 after determination in step 304. If data transmission is performed, the variable i as a loop counter is determined in step 322. “0” is set, and the color measurement data DT [i] is sequentially transmitted by the following loop processing. The data format at this time is shown in FIG. 16. As shown in FIG. 16, in step 324, the data number, the colorimetric data, and the separator are repeatedly transmitted. In step 326, the variable i of the loop counter is sequentially increased. In step 328, the loop is exited if it is determined that the variable DTn is exceeded.

  When the colorimeter performs this data transmission, the process on the personal computer 10 side corresponds to the colorimeter calibration data input process in step 500 and the colorimetric data input process in step 600 shown in FIG. In general, when data is input from an external device such as a colorimeter, serial communication is often performed by connecting to the serial port shown in FIG. Of course, a floppy disk drive may be attached to the colorimeter and data may be exchanged via the floppy disk.

By the way, in step 500, the colorimeter calibration data input process is executed, and before that, in step 400, the media information input process is executed, which will be described. First, in the media information input process, while displaying a screen for inquiring the operator of the type of print paper (media), information on what the print paper is is obtained after waiting for an input with the keyboard 25 or the mouse 26.
Accordingly, there are several types of print sheets to be displayed, and for the corresponding print sheets, colorimeter calibration data measured in advance by a standard colorimeter is prepared.

  On the other hand, the color patches are printed with 1 cm square patches arranged as shown in FIG. 11, but the first patch is a blank patch printed only on the frame, and this is the calibration of the colorimeter actually used. Patch. The colorimetric data obtained by measuring the calibration patch is colorimetric data [0] in the data format shown in FIG. 16. Strictly speaking, the input process of the colorimetric data [0] is performed in step 500. This corresponds to the color calibration data input processing, and the input processing after the color measurement data [1] corresponds to the color measurement data input processing in step 600.

  The colorimetric data [0] measured for the blank patch is not only the measured color data of the media, but also calibration data corresponding to the input media information if no reading error occurs in the colorimeter itself. Match. However, the colorimeter itself may change over time, and it is troublesome to perform special calibration in this case. As in this embodiment, if it is decided to measure the color of a blank patch first, and if calibration can be performed with the colorimetric data, the measurement is extremely simple, accurate, and without any consciousness. Color can be done. Blank patches are most conveniently placed at the very beginning for this purpose, but in some cases they can be scattered across multiple locations on the print paper, giving subtle differences in the colorimetric environment. The impact can also be measured.

The above calibration is executed in step 800 together with the calculation of the color correction correspondence. Here, as shown in FIG. 9, actual color data correction, color correction correspondence calculation / table creation, and media-specific LUT creation are executed.
First, in order to execute calibration as a premise, an actual color data correction process shown in FIG. 17 is executed. When the colorimeter calibration data measured by the standard colorimeter is specified based on the input media information as described above, a deviation from the colorimetric data [0] is obtained.

That is, if the standard white data prepared for the media is Cws, Mws, Yws and the colorimetric data [0] is Cwu, Mwu, Ywu, the values are set in step 802 and step 804, respectively. Read and set the ratio between the two as a uniform correction factor. That is, in order to obtain the corrected actual color data Cu1, Mu1, Yu1 obtained by performing correction based on calibration for the subsequent actual color data Cu0, Mu0, Yu0, as shown in step 806,
Cu1 = (Cws / Cwu) × Cu0 (Cu1> 255 then Cu1 = 255)
Mu1 = (Mws / Mwu) × Mu0 (Mu1> 255 then Mu1 = 255)
Yu1 = (Yws / Ywu) × Yu0 (Yu1> 255 then Yu1 = 255)
Asking. In actual work, Cws / Cwu, Mws / Mwu, Yws / Ywu corresponding to the correction coefficient are obtained, the actual color data is read from the actual color data file, multiplied by the correction coefficient, and the product is corrected. Write to

Next, the color correction correspondence is calculated using the actually measured color data file and the standard color data file prepared for each printing paper. FIG. 18 shows a flowchart when a Lagrangian interpolation formula is used in calculating the color correction correspondence, and FIG. 19 shows a specific part of a specific coding list.
First, the calculation of the color correction correspondence will be briefly described.
Prepare a standard printer with the same amount of color ink to be used, print color patches over all gradation values (256 gradations) using this standard printer, and provide a colorimeter with no measurement error. Prepare standard color data (DT [0] to DT [255]) using each color patch. In the following, data will be described as an integral unit, but each includes individual data about CMY.

On the other hand, the printer 50 to be actually calibrated prints a color patch with a plurality of gradation values (dg [1] to dg [n]) determined as described above, and measures the color. In addition to the actually measured color data (dt0 [0] to dt0 [n]), the above-described correction is performed to obtain corrected actually measured color data (dt1 [0] to dt1 [n]).
Then, this corrected measured color data (dt1 [0] to dt1 [n]) is compared with the standard color data (DT [0] to DT [255]) to find the combination with the least error, and the standard in that case Find the tone values (dg_s [1] to dg_s [n]) of the color data.

  Here, the relationship between the gradation values given for patch printing (dg [1] to dg [n]) and the gradation values (dg_s [1] to dg_s [n]) that match as described above is When the gradation values (dg [1] to dg [n]) of the printer 50 are printed, the gradation values (dg_s [1] to dg_s) printed by the standard printer are actually printed. [n]), which indicates that color misregistration has occurred.

とすると、ラグランジュ補間式となる。なお、右辺のΠ｛(x-xj)/(xi-xj)｝は、(x-xj)/(xi-xj)をj=i 以外の全てのｊについて掛け合わせたものを意味する。 However, if it is desired to reverse this correspondence and reproduce a desired color, the gradation value to be given may be corrected in advance. This is to obtain the correspondence for correction by calculation.
When this correspondence is obtained by calculation, a first method is a method using a high-order interpolation formula. If Lagrangian interpolation is used as this higher-order interpolation, if n points (dg [1], dg_s [1]) ... (dg [n], dg_s [n]) are given,
dg [i] = P (dg_s [i]) (i = 0,1, ... n-1)
N-1 degree polynomial satisfying
P (x) = (Fn-1) ・ x ** (n-1) + (Fn-2) ・ x ** (n-2) +… + F1 ・ x + F0
Is uniquely determined. This is expressed as a closed general formula,

Then, the Lagrange interpolation formula is obtained. Note that Π {(x-xj) / (xi-xj)} on the right side means a product of (x-xj) / (xi-xj) multiplied by all j except j = i.

Therefore, if this Lagrangian interpolation formula is used, the correction to be made to obtain the print result that matches the standard color data (DT [0] to DT [255]) at the desired gradation value (0 to 255) The gradation value (dg_L [0] to dg_L [255]) is known. This table represents the parameter table.
In the flowchart shown in FIG. 18, in step 820, the corrected actually measured color data (dt1 [0] to dt1 [n]) and the standard color data (DT [0] to DT [255]) are compared and the corresponding floors are compared. An operation for finding a tone value (dg_s [1] to dg_s [n]) is executed. In step 822, a gradation value (0 to 255) that does not cause a color shift using a Lagrange interpolation equation ( dg_L [0] to dg_L [255]). FIG. 19 shows a specific coding list. If dg is substituted for y, dg_s is substituted for x, and a desired gradation value is substituted for t, the corresponding gradation value is input to sum.

On the other hand, it is possible to obtain the color correction correspondence relationship other than using the higher-order interpolation formula as described above. FIG. 20 shows the gradation to be given in order to obtain the standard color data (DT [0] to DT [255]) at the desired gradation value (0 to 255) using the correction formula by obtaining the regression coefficient by the least square method. A flow for obtaining values (dg_r [0] to dg_r [255]) is shown.
The least squares method itself is the same as described above.
P (x) = (Fn-1) ・ x ** (n-1) + (Fn-2) ・ x ** (n-2) +… + F1 ・ x + F0
Is a process for obtaining a coefficient (Fn-1, Fn-2,... F1, F0) that minimizes the error when there is a relationship, and this coefficient is called a regression coefficient. A specific coding example is shown in FIG. In this case, the regression coefficients b1 and b0 are obtained by giving n sets (dg [1], dg_s [1])... (Dg [n], dg_s [n]) as a matrix x. In step 840, n groups (dg [1], dg_s [1])... (Dg [n], dg_s [n]) are prepared, and the regression coefficient b1 is determined in step 842 according to the coding list shown in FIG. , b0 is calculated. In step 846, based on the linear interpolation equation using the regression coefficients b1 and b0, the corrected gradation values (dg_R [0] to dg_R [255] that do not cause color shift in the desired gradation values (0 to 255). ]) Get.

  Referring to FIG. 9, when the color correction correspondence calculation and table creation are completed, a parameter table composed of the above correspondence is created, and subsequently, media-specific LUT creation is performed. This includes two elements. First, since a standard LUT is prepared as a color conversion table, the parameter table is applied to eliminate the color shift described above. When the parameter table is applied to output a certain gradation value in the standard LUT, the above parameter is used as an argument so that the color corresponding to the gradation value is actually output. Rewrite with the modified gradation values (dg_L [0] to dg_L [255] or dg_R [0] to dg_R [255]) written in the table.

  The second point is that an LUT is created for each medium. In this embodiment, only a standard LUT is provided, and instead of providing a media-specific LUT, correction information corresponding to other media and modes is provided as media-specific information. Specifically, it is a one-dimensional correction table similar to the parameter table as described above. This one-dimensional correction table takes into account the occurrence of color misregistration due to differences in the physical properties of the media, for example, the amount of color ink absorbed, and the correspondence relationship for correcting the tone values so as to eliminate the influence of these physical properties Is recorded. For example, if the medium is an OHP sheet, the dot area tends to be large because it spreads on the surface without being absorbed inside the medium, so the influence is subtracted as a gradation value over all gradations. become.

  In addition, there are other factors that cannot be corrected simply based on the correction relationship based on the matching of each gradation value as described above due to, for example, the difference in print mode, and a correction table is used to eliminate this. May be. In this case, a separate LUT is prepared for each printable mode. Furthermore, as another example, if only a single color is to be corrected, the above correction should be able to be completely corrected. However, it is empirically recognized that the correction amount becomes too large when mixed colors are used, and adjustment is made to reduce the correction amount. Is available.

  In the process for creating a media-specific LUT, the parameter table, the standard LUT, and the media-specific information are input, and the parameter table and the one-dimensional correction table for the media-specific LUT are applied to the standard LUT, thereby creating a plurality of media-specific LUT # 1. , # 2... That is, in the process for creating the LUT for each medium, the standard LUT value is rewritten based on the parameter table (dg_L [i], dg_R [i]) in step 902 as shown in FIG. Based on the information (MD [i]), the value of the standard LUT is rewritten again. Of course, it is possible to rewrite the standard LUT value only once after creating a correction table that combines the parameter table (dg_L [i], dg_R [i]) and the media-specific information (MD [i]). is there.

Returning to FIG. 8, through the above processing, all processing from patch printing control to creation of media-specific LUTs is completed, and a color conversion table for each media including a calibration function is created.
In the present invention, it is not essential to create a color conversion table called an LUT, and it is only necessary to create a color correction table for correcting such an LUT. Therefore, various implementations are included. A program for creating a color conversion table, as in the present embodiment, is one aspect thereof. In this sense, the program can be realized as an independently executable utility, but can also be realized as a printer driver for print processing.

  FIG. 23 shows an example of incorporation into a printer driver. In this printer driver, at the time of start-up or calling, it is determined whether or not printing processing is performed in step 1005. If not printing processing, patch printing to color correction table creation is performed in the same manner as described above (steps 1010 to 1030). ). Here, if the correspondence between each step in this process and the process shown in FIG. 8 is clarified, the patch printing process executed in step 1010 corresponds to the patch printing control in step 200, and is executed in step 1015. The actual color data acquisition process corresponds to the actual color data input process in step 600, the standard color data acquisition process performed in step 1020 corresponds to the standard color data read process in step 700, and the color correction performed in step 1025. The correspondence calculation processing and the table creation processing executed in step 1030 correspond to the actual color data correction / color correction correspondence calculation / table creation processing in step 800.

  When executing the printing process, color image data is input in step 1035 and color conversion is performed in step 1040. If the color image data has general RGB 256 gradations, the printer 50 requires CMYK 2 gradation printing color image data, so that color conversion and gradation conversion are required. In step 1040, the RGB 256 gradation color image data is converted into CMYK 256 gradation color image data. At this time, color conversion may be performed using the standard LUT as described above. In the next step 1045, the color image data of CMYK256 gradation is corrected using the color correction table created in step 1030. Also in this case, since a one-dimensional correction table is prepared for each color, color image data may be rewritten with reference to each table value using an output gradation value as an argument. Thereafter, in step 1050, CMYK256 gradation is halftoned to CMYK2 gradation, and in step 1055, the halftoned data is transmitted from the personal computer 10 to the printer 50 by parallel communication.

  On the other hand, when the CMYK two-tone printing color image data is input on the printer 50 side, the paper feed motor 62 feeds the paper while moving the print head unit 61 to the left and right by the carriage motor 59, and a desired print paper is obtained. While moving the print head unit 61 to the position, dots of color ink are adhered. At this time, although the color reproduction that the printing color image data is going to directly represent due to the individual difference of the print head unit 61 is not performed, this printing color image data eliminates the individual difference of the print head as described above. As a result, the color image data is corrected, and the print result itself has a color reproducibility corresponding to the color image data.

In the above, the processing of the present invention has been described on the premise of software processing, but it is also possible to realize it by a hardware configuration. FIG. 24 shows a schematic block diagram in the case of incorporation in a printer with a hardware configuration.
The printer 80 is realized by a color image data acquisition circuit 81 including an interface and a memory and a gate array circuit for changing the color space and gradation of the color image data as a configuration for realizing a general printing function. A color conversion circuit 82 and a gradation conversion circuit 83, and a color printing mechanism 84 realized with a mechanism mainly for driving and printing the print head while feeding printing paper. The color conversion circuit 83 includes a color correction circuit 85 for performing calibration when color conversion is performed, and a patch colorimetric data acquisition circuit 86 and a standard for creating a color correction table as correction information. A color data acquisition circuit 87 and a color correction correspondence calculation circuit 88 are also provided. The patch colorimetric data acquisition circuit 86 can be realized by a configuration in which data is acquired from outside by communication or data is acquired by a floppy disk or the like, and other than these, an arithmetic unit incorporating a gate array circuit or a microcomputer It is realized by using etc. On the other hand, color patches to be colorimetrically measured can be obtained by always performing the same control on the color printing mechanism 84, so that colorimetric patch printing control is performed by a gate array circuit or the like in order to perform routine operations. A circuit 89 is realized.

  In this way, the printer 50 prints color patches of a predetermined plurality of colorimetric gradation values, obtains measured color data obtained by measuring the color patches with the colorimeter, and supports all gradation values. If the corresponding color values are obtained and the corresponding gradation values are referred to, the correspondence relationship between the color measurement gradation value and the same gradation value can be obtained. It is possible to calculate a correction correspondence that can obtain a print result, and to create a color correction table according to this.

It is a flowchart which shows the general | schematic procedure of the color correction table preparation program concerning one Embodiment of this invention. It is a schematic block diagram of a personal computer. It is a schematic block diagram which shows the connection condition of the peripheral device to a personal computer. It is a figure which shows the structure of the software of a personal computer. It is a schematic block diagram of a printer. It is a schematic explanatory drawing of the print head unit in the color printer. FIG. 3 is a schematic explanatory diagram illustrating a state in which color ink is ejected by the print head unit. It is a general | schematic flowchart of this color correction table creation program. It is a figure which shows the file input / output in the same color correction table creation program. It is a flowchart of a patch printing control process. It is a figure which shows the printing condition of a color patch. It is a graph which shows the correspondence of the change of the measurement color data with respect to the change of a gradation value. It is a graph which shows the correspondence of the variation | change_quantity of the actual color data with respect to the unit variation | change_quantity of a gradation value. It is a graph which shows the correspondence of the quantization error which can arise for every gradation value. It is a main flowchart of a colorimeter. It is a figure which shows the data format of the actual color data which a colorimeter outputs. It is a flowchart of measured color data correction processing. It is a flowchart of the color correction corresponding | compatible relationship calculation process using a Lagrange interpolation calculation. It is a coding list of Lagrange interpolation calculation. It is a flowchart of the color correction corresponding relationship calculation process using the least square method. This is a least-squares coding list. It is a flowchart of LUT creation processing for each medium. 3 is a flowchart when the printer driver is incorporated. FIG. 3 is a block diagram when the printer is incorporated as a hardware circuit.

Explanation of symbols

10 ... PC 11 ... CPU
12 ... CPU bus 13 ... secondary cache 14 ... data bus unit 15 ... system controller 16 ... memory 17 ... PCI bus 18 ... common interface 19 ... bus master 19a ... hard disk 19b ... CD-ROM drive 21 ... PCI device 21a ... SCSI card 22 ISA bridge 23 ISA bus 24 ISA device 24 a PCMCIA card 25 keyboard 26 mouse 27 printer 28 modem 29 scanner 31 digital video camera 32 magneto-optical storage device 33 PCMCIA card socket 34 memory card 35 ... Digital still camera 41 ... Hardware 42 ... BIOS 43 ... Operating system 43a ... Printer driver 44 ... Application 50 ... Printer 50 ... Printer 51 ... Para Le inter Fi Es 52 ... Gate Array 54 ... Bus 55 ... CPU
56 ... System ROM
57 ... Character ROM
58 ... D-RAM
59 ... Carriage motor 61 ... Print head unit 61a ... Print head 61a1 ... Color ink tank 61a2 ... Nozzle 61a3 ... Pipe 61a4 ... Ink chamber 61a5 ... Piezo element 62 ... Paper feed motor 63 ... Timer counter 64 ... EEPROM
65 ... Operation panel 70 ... Parallel connection cable 80 ... Printer 81 ... Color image data acquisition circuit 82 ... Color conversion circuit 83 ... Gradation conversion circuit 84 ... Color printing mechanism 85 ... Color correction circuit 86 ... Patch colorimetric data acquisition circuit 87 ... Standard color data acquisition circuit 88 ... Color correction correspondence calculation circuit 89 ... Color measurement patch print control circuit

Claims (4)

Based on multi-tone color image data obtained by color-separating a plurality of pixels in a dot matrix form of a color image for each predetermined element color, a dot-shaped recording material for each predetermined element color is adhered onto a print medium. A color image data correction device for correcting color misregistration in the printer by changing the color image data for a printer that prints the same color image;
Actual color data acquisition means for acquiring actual color data obtained by measuring the print result of predetermined image data printed by the printer;
Standard color data acquisition means for acquiring standard color data which is a standard print result of the predetermined image data;
Table creating means for creating a color correction table for changing the color image data based on the correspondence between the measured color data and the standard color data;
Comprising
The predetermined image data has a non-constant gradation interval so that the change amount of the colorimetric result with respect to the change of the gradation value is denser in the gradation region that is larger than the predetermined change amount as compared with the outside of the gradation region. Contains multiple gradation values set in ,
The measured color data acquisition means is a color image data correction device for measuring the printing result of the printer at the plurality of gradation values . The image data is expressed in 256 tones,
The color image data correction device according to claim 1, wherein the measured color data acquisition unit measures the gradation values 0 to 50 more densely than the gradation values 50 to 255 when measuring the print result. Based on multi-tone color image data obtained by color-separating a plurality of pixels in a dot matrix form of a color image for each predetermined element color, a dot-shaped recording material for each predetermined element color is adhered onto a print medium. A color image data correction method for correcting a color shift in the printer by changing the color image data for a printer that prints the same color image,
An actual color data acquisition step of acquiring actual color data obtained by measuring the print result of the predetermined image data printed by the printer;
A standard color data acquisition step of acquiring standard color data which is a standard print result of the predetermined image data;
A table creating step for creating a color correction table for changing the color image data based on the correspondence between the measured color data and the standard color data;
Have
The predetermined image data has a non-constant gradation interval so that the change amount of the colorimetric result with respect to the change of the gradation value is denser in the gradation region that is larger than the predetermined change amount as compared with the outside of the gradation region. Contains multiple gradation values set in ,
The measured color data acquisition step is a color image data correction method for measuring colors of the printing results of the printer at the plurality of gradation values . Based on multi-tone color image data obtained by color-separating a plurality of pixels in a dot matrix form of a color image for each predetermined element color, a dot-shaped recording material for each predetermined element color is adhered onto a print medium. A color image data correction program for correcting color misregistration in the printer by changing the color image data for a printer that prints the same color image,
An actual color data acquisition function for acquiring actual color data obtained by measuring the print result of predetermined image data printed by the printer;
A standard color data acquisition function for acquiring standard color data which is a standard print result of the predetermined image data;
A table creation function for creating a color correction table for changing the color image data based on the correspondence between the measured color data and the standard color data;
Is realized on a computer,
The predetermined image data has a non-constant gradation interval so that the change amount of the colorimetric result with respect to the change of the gradation value is denser in the gradation region that is larger than the predetermined change amount as compared with the outside of the gradation region. Contains multiple gradation values set in ,
The measured color data acquisition function is a color image data correction program for measuring colors of the printing results of the printer at the plurality of gradation values .

Images