JP7352350B2 - Inkjet printer color matching method and inkjet printer color matching device - Google Patents

Description

The present invention relates to a color matching method for an inkjet printer and a color matching device for an inkjet printer.

2. Description of the Related Art Conventionally, techniques for color matching between multiple inkjet printers have been known. Even if inkjet printers of the same model are used, their color development differs depending on, for example, ICC (International Color Consortium) profiles and other settings, and individual differences between inkjet printers. Color matching is performed, for example, when it is desired to directly transfer the color development of one inkjet printer to another inkjet printer.

For example, Patent Document 1 discloses a method of performing color matching in an inkjet printer using an option that emphasizes perception and an option that emphasizes colorimetric values. In the method disclosed in Patent Document 1, when there is a large difference between the color reproduction range of the first printer and the color reproduction range of the second printer, color matching is performed using a perception-oriented option. Furthermore, if the difference between the color reproduction range of the first printer and the color reproduction range of the second printer is small, color matching is performed using an option that emphasizes colorimetric values. In the method disclosed in Patent Document 1, color matching is performed using an ICC profile in any option.

Japanese Patent Application Publication No. 2002-118759

Differences in color development between multiple inkjet printers may be due to differences in set ICC profiles or due to other causes. If the cause of the difference in color development is a difference in ICC profile, it is effective to perform color matching using the ICC profile. In such cases, it is often impossible to match the colors even if adjustments are made for each ink color. Conversely, if the cause of the difference in color development is a cause other than the difference in ICC profiles, it is efficient to perform color matching for each ink color. However, in the method disclosed in Patent Document 1, the only color matching method is a method using an ICC profile, which may not necessarily be efficient.

The present invention has been made in view of this point, and its purpose is to provide a method for more efficiently performing color matching in an inkjet printer. Another object of the present invention is to provide a color matching device that can more efficiently match the colors of an inkjet printer.

The color matching method for an inkjet printer disclosed herein is a method for color matching a second inkjet printer based on a first inkjet printer, and includes a determination step and an adjustment step. In the determination step, a first ICC profile used in the first inkjet printer and a second ICC profile used in the second inkjet printer are compared, and the first ICC profile and the second ICC profile are compared. It is determined whether the two ICC profiles are the same or similar. In the adjustment step, if the first ICC profile and the second ICC profile are determined to be the same or similar in the determination step, the color development of the second inkjet printer is adjusted for each ink color. .

Further, the color matching device for an inkjet printer disclosed herein includes a communication port configured to be connectable to an inkjet printer, and a control device connected to the communication port. The control device includes a storage section, an acquisition section, a determination section, and an adjustment section. The storage unit stores a first ICC profile. The acquisition unit reads a second ICC profile used in an inkjet printer connected to the communication port. The determination unit compares the first ICC profile and the second ICC profile, and determines whether the first ICC profile and the second ICC profile are the same or similar. The adjusting unit is configured to use the first ICC profile and the second ICC profile when the determining unit determines that the first ICC profile and the second ICC profile are dissimilar. color matching of the inkjet printer connected to the communication port.

In the above color matching method for an inkjet printer, a first ICC profile used in the first inkjet printer and a second ICC profile used in the second inkjet printer are compared, and the first ICC profile and the second ICC profile used in the second inkjet printer are compared. When the second ICC profile is the same or similar, the color development of the second inkjet printer is adjusted for each ink color. According to the above color matching method for inkjet printers, color matching for each ink color is performed only when the cause of the difference in color development does not include a difference in ICC profile, so color matching for inkjet printers is performed efficiently. be able to.

Further, according to the color matching device for an inkjet printer, the first ICC profile serving as a reference and the second ICC profile used in the inkjet printer to be adjusted are compared, and the first ICC profile and the second ICC profile are compared. If the ICC profiles are dissimilar, the first ICC profile and the second ICC profile are used to perform color matching of the inkjet printer to be adjusted. Therefore, at least when the cause of the difference in color development from the reference includes a difference in ICC profile, efficient color matching can be performed.

1 is a schematic diagram showing a configuration example of a color matching system for an inkjet printer according to an embodiment. FIG. 3 is a front view of the second printer. FIG. 1 is a block diagram of a color matching system. 7 is a flowchart showing the flow of determining whether ICC profiles are identical or similar by the color matching device. It is a flowchart showing the flow of monochromatic color matching. FIG. 2 is a plan view schematically showing an example of a test chart. 3 is a flowchart showing the flow of color matching using an ICC profile.

Hereinafter, a color matching system for an inkjet printer according to an embodiment of the present invention will be described with reference to the drawings. Note that the embodiments described here are not intended to particularly limit the present invention, as a matter of course. In addition, the same reference numerals are given to members and parts that have the same function, and redundant explanations are omitted or simplified as appropriate.

FIG. 1 is a schematic diagram showing a configuration example of a color matching system for an inkjet printer (hereinafter referred to as a color matching system 200) according to an embodiment. As shown in FIG. 1, the color matching system 200 includes a color matching device 100 and a colorimeter 190. The color matching device 100 here is a computer in which software for adjusting the color development of the printer is installed. However, the color matching device 100 may be a dedicated device that includes hardware and software for adjusting the color production of the printer. A first printer 10A and a second printer 10B are each communicably connected to the color matching device 100. The details will be described later, but here, the second printer 10B is the printer to be adjusted, and the color development is adjusted based on the first printer 10A. The first printer 10A and the second printer 10B are printers of the same model. In the following description, first the configurations of the first printer 10A and the second printer 10B will be described, and then the color matching system 200 including the color matching device 100 will be described. Note that the configurations of the first printer 10A and the second printer 10B are not particularly limited, and the configuration described below is just one example.

FIG. 2 is a front view of the second printer 10B. In the following description, when the second printer 10B is viewed from the front, the direction moving away from the second printer 10B will be referred to as the front, and the direction approaching the second printer 10B will be referred to as the rear. Left, right, top, and bottom mean the left, right, top, and bottom, respectively, when the second printer 10B is viewed from the front. Further, the symbols F, Rr, L, R, U, and D in the drawings mean front, rear, left, right, top, and bottom, respectively. Further, the symbol Y in the drawings indicates the main scanning direction. Here, the main scanning direction Y is the left-right direction. The symbol X indicates the sub-scanning direction. Here, the sub-scanning direction X is the front-rear direction, and is perpendicular to the main-scanning direction Y in plan view (see FIG. 6). However, the above-mentioned direction is merely a direction determined for convenience of explanation, and does not limit the installation mode of the second printer 10B in any way, nor does it limit the present invention in any way.

The second printer 10B is an inkjet printer. The second printer 10B is a so-called large-sized printer that is longer in the main scanning direction Y than a home-use printer. The second printer 10B is, for example, a printer for business use. In the present embodiment, the second printer 10B sequentially moves the roll-shaped recording medium 5 forward, and also includes a first ink head 30A, a second ink head 30B, which are mounted on a carriage 30 that moves in the main scanning direction Y. An image is printed on the recording medium 5 by ejecting predetermined ink from the third ink head 30C and the fourth ink head 30D.

The recording medium 5 is, for example, recording paper. However, the recording medium 5 is not limited to recording paper. For example, the recording medium 5 includes a relatively thick sheet such as a sheet made of a resin material such as PVC or polyester, a metal plate made of aluminum or iron, a glass plate, a wood plate, or the like.

As shown in FIG. 2, the second printer 10B includes a main body 11, legs 12, an operation panel 13, a platen 16, and a printer control device 40. The main body portion 11 has a casing extending in the main scanning direction Y. The legs 12 support the main body 11. The legs 12 are provided on the lower surface of the main body 11. The operation panel 13 is provided on the right front side of the main body section 11. However, the position of the operation panel 13 is not particularly limited. On the operation panel 13, for example, a user performs operations related to printing. Although not shown, the operation panel 13 includes, for example, a display unit that displays printing-related information such as resolution, ink ejection amount (ink weight), and the status of the second printer 10B that is currently printing; It is equipped with an input section for inputting information regarding printing.

The platen 16 is a member that supports the recording medium 5 during printing on the recording medium 5. The recording medium 5 is placed on the platen 16 . Printing on the recording medium 5 is performed on a platen 16. The platen 16 extends in the main scanning direction Y. The platen 16 is provided on the main body portion 11.

As shown in FIG. 2, the second printer 10B includes a carriage 30 and a head moving mechanism 31. The head moving mechanism 31 is a mechanism that moves the carriage 30 in the main scanning direction Y. The head moving mechanism 31 includes a guide rail 20, a pulley 21, a pulley 22, an endless belt 23, and a carriage motor 24. The guide rail 20 guides the movement of the carriage 30 in the main scanning direction Y. The guide rail 20 is arranged above the platen 16. The guide rail 20 is provided on the main body part 11. The guide rail 20 extends in the main scanning direction Y. The pulley 21 is provided to the left of the left end of the guide rail 20. The pulley 22 is provided to the right of the right end of the guide rail 20. The belt 23 is wound around the pulley 21 and the pulley 22. A carriage motor 24 is connected to the pulley 22 on the right side. However, the carriage motor 24 may be connected to the left pulley 21. When the carriage motor 24 is driven and the pulley 22 rotates, the belt 23 runs between the pulleys 21 and 22.

Carriage 30 is attached to belt 23. The carriage 30 is engaged with the guide rail 20 and is slidably provided on the guide rail 20. The carriage 30 is equipped with a first ink head 30A to a fourth ink head 30D. As the belt 23 is driven by the carriage motor 24 and the carriage 30 moves in the main scanning direction Y, the first to fourth ink heads 30A to 30D mounted on the carriage 30 move in the main scanning direction Y. Moving.

The second printer 10B includes a medium transport mechanism 32. The medium transport mechanism 32 is a mechanism that moves the recording medium 5 placed on the platen 16 in the sub-scanning direction X (see FIG. 6). The medium transport mechanism 32 includes a grit roller 25, a pinch roller 26, and a feed motor 27 (see FIG. 3). The grit roller 25 is provided on the platen 16. Here, part of the grit roller 25 is embedded in the platen 16. The pinch roller 26 is arranged above the grit roller 25 so as to face the grit roller 25 in the vertical direction. The pinch roller 26 is a member that presses down the recording medium 5 from above. The pinch roller 26 may be configured to be movable in the vertical direction depending on the thickness of the recording medium 5. Note that the positions and numbers of the grit rollers 25 and pinch rollers 26 are not particularly limited. Feed motor 27 is connected to grit roller 25. When the feed motor 27 is driven and the grit roller 25 rotates with the recording medium 5 sandwiched between the grit roller 25 and the pinch roller 26, the recording medium 5 is conveyed in the sub-scanning direction X.

As shown in FIG. 1, the first ink head 30A, the second ink head 30B, the third ink head 30C, and the fourth ink head 30D are arranged in the main scanning direction Y. The first ink head 30A to the fourth ink head 30D are formed to have the same shape and size. The first ink head 30A to the fourth ink head 30D each include a plurality of nozzles (not shown) arranged in the sub-scanning direction X. Here, the first ink head 30A discharges cyan ink onto the recording medium 5. The second ink head 30B discharges magenta ink onto the recording medium 5. The third ink head 30C discharges yellow ink onto the recording medium 5. The fourth ink head 30D discharges black ink onto the recording medium 5. However, the inks ejected from the first ink head 30A to the fourth ink head 30D are not limited to those described above. By ejecting ink onto the recording medium 5 from the first ink head 30A to the fourth ink head 30D, an image or a test chart to be described later is formed on the recording medium 5.

The printer control device 40 controls the operation of each part of the second printer 10B. Also, perform various settings related to printing. The configuration of printer control device 40 is not particularly limited. The printer control device 40 is, for example, a microcomputer. The hardware configuration of the microcomputer is not particularly limited, but includes, for example, an interface (I/F) that receives print data from an external device such as a host computer, and a central processing unit (CPU) that executes instructions of a control program. central processing unit), ROM (read only memory) that stores programs executed by the CPU, RAM (random access memory) that is used as a working area to expand programs, and memory that stores programs and various data. It is equipped with a storage device. As shown in FIG. 2, the printer control device 40 is provided inside the main body 11. As shown in FIG. However, the printer control device 40 does not have to be provided inside the main body section 11. For example, the printer control device 40 may be a computer installed outside the main body 11. For example, some functions of the printer control device 40 may be realized by a computer in which the color matching device 100 is configured.

FIG. 3 is a block diagram of the color matching system 200 according to this embodiment. As shown in FIG. 3, the printer control device 40 includes an image input module 41, a monochromatic color matching module 42, a color conversion module 43, a halftone module 44, and a rasterization module 45 as processing units related to image processing. It is equipped with The printer control device 40 includes a print control section that controls the movement of each section during printing, but description and illustration thereof will be omitted here.

Print image data is input to the image input module 41 . Print image data is created, for example, by a computer included in the color matching device 100 and sent to the image input module 41. The second printer 10B performs printing based on the print image data input to the image input module 41. The print image data here is color data of CMYK values.

The monochromatic color matching module 42 adjusts the color production of the inkjet printer for each ink color (hereinafter, this color matching method is also referred to as "monochromatic color matching"). In this embodiment, the printer to be adjusted is the second printer 10B. Therefore, the monochrome color matching module 42 of the second printer 10B performs monochrome color matching of the second printer 10B. Details of monochromatic color matching will be described later.

The color conversion module 43 uses an ICC (International Color Consortium) profile to convert device-dependent print image data (here, CMYK ink values) into device-independent color space color values (here, L ^* a ^*) . b ^* value), or convert the color value of a device-independent color space (here, L ^* a ^* b ^* value) to device-dependent print data (here, CMYK ink value. Below, as appropriate, (also simply called ink value). To convert device-dependent print image data into color values in a device-independent color space, a conversion table called an A2B table in the ICC profile is used. Conversely, when converting color values in a device-independent color space to device-dependent print data, a conversion table called a B2A table in the ICC profile is used.

The halftone module 44 converts the ink values created by the color conversion module 43 into dot data. Furthermore, the rasterization module 45 converts the dot data created by the halftone module 44 into data for each pass. The second printer 10B performs printing by executing the dot data for each pass created by the rasterization module 45.

The first printer 10A also has the same configuration as the second printer 10B. However, in FIG. 3, illustration of the internal configuration of the first printer 10A is omitted.

The color matching device 100 is a device that instructs a connected printer to perform color matching based on the instructions. Here, the color matching device 100 performs color matching of the second printer 10B using the first printer 10A as a reference. More specifically, the second printer 10B is adjusted so that the color produced by the second printer 10B approaches the color produced by the first printer 10A.

As shown in FIG. 3, the color matching device 100 includes a first communication port 101, a second communication port 102, and a control device 103. The first communication port 101 is configured to be connectable to an inkjet printer, and here is connected to the first printer 10A. The second communication port 102 is also configured to be connectable to an inkjet printer, and here is connected to the second printer 10B.

The control device 103 is connected to the first communication port 101 and the second communication port 102. Therefore, the control device 103 is communicably connected to the first printer 10A and the second printer 10B via the first communication port 101 and the second communication port 102, respectively. The control device 103 is also communicably connected to a colorimeter 190. As shown in FIG. 3, the control device 103 includes an acquisition section 110, a storage section 120, a determination section 130, a first adjustment section 140, and a second adjustment section 150.

The acquisition unit 110 includes a first acquisition unit 111 and a second acquisition unit 112. The first acquisition unit 111 is set to read the ICC profile used in the inkjet printer connected to the first communication port 101. Here, the first acquisition unit 111 reads the ICC profile of the first printer 10A. The second acquisition unit 112 is set to read the ICC profile used in the inkjet printer connected to the second communication port 102. The second acquisition unit 112 here reads the ICC profile of the second printer 10B.

The storage unit 120 is configured to store the ICC profile of the inkjet printer to be adjusted and the ICC profile of the reference inkjet printer. The storage unit 120 includes a first storage unit 121 and a second storage unit 122. The first storage unit 121 stores the ICC profile read by the first acquisition unit 111. Hereinafter, the ICC profile read out by the first acquisition unit 111 will be referred to as a first ICC profile. The first ICC profile is the ICC profile used by the first printer 10A. Similarly, the second storage unit 122 stores the ICC profile read by the second acquisition unit 112. Hereinafter, the ICC profile read out by the second acquisition unit 112 will be referred to as a second ICC profile. The second ICC profile is the ICC profile used by the second printer 10B.

The determining unit 130 compares the first ICC profile and the second ICC profile, and determines whether the first ICC profile and the second ICC profile are the same or similar. As shown in FIG. 3, the determination unit 130 includes a first calculation unit 131, a second calculation unit 132, a third calculation unit 133, a fourth calculation unit 134, a fifth calculation unit 135, and a sixth calculation unit 136. ing.

The first calculation unit 131 inputs each ink value (CMYK ink value) into the A2B table of the first ICC profile, and calculates a color value (L ^* a ^* b ^* value) for each input ink value. The input ink value is an ink value that is set in advance and stored in the control device 103.

The second calculation unit 132 inputs each ink value into the A2B table of the second ICC profile, and calculates a color value for each input ink value. The CMYK ink values input to the second calculation unit 132 are the same as the CMYK ink values input to the first calculation unit 131. Hereinafter, the CMYK ink values input to the first calculation section 131 and the second calculation section 132 will also be referred to as "input ink values" as appropriate.

The third calculation unit 133 calculates the color difference between the color value calculated by the first calculation unit 131 and the color value calculated by the second calculation unit 133 for each input ink value. The color difference ΔE ^* _ab corresponding to one input ink value is calculated by the following formula.
ΔE ^* _ab = {(L ^* ₁ - L ^* ₂ ) ² + (a ^* ₁ - a ^* ₂ ) ² + (b ^* ₁ - b ^* ₂ ) ² } ^1/2
ΔE ^* _ab is the color difference. L ^* ₁ and L ^* ₂ are the L ^* value transformed by the first ICC profile and the L ^* value transformed by the second ICC profile, respectively. a ^* ₁ and a ^* ₂ are the a ^* value transformed by the first ICC profile and the a ^* value transformed by the second ICC profile, respectively. b ^* ₁ and b ^* ₂ are the b ^* value transformed by the first ICC profile and the b ^* value transformed by the second ICC profile, respectively. The color difference ΔE ^* _ab represents a distance in a three-dimensional color space. However, the method for determining the color difference ΔE ^* _ab described above is only one suitable method, and other calculation formulas may be used.

The fourth calculation unit 134 calculates the representative value ΔE of the color difference ΔE ^* _ab for each input ink value based on the color difference ΔE ^* _ab for each input ink value calculated by the third calculation unit 133. Here, the representative value ΔE is the average value of the color difference ΔE ^* _ab for each input ink value. However, the representative value ΔE may not be the average value of the color difference ΔE ^* _ab for each input ink value, but may be, for example, the maximum value of the color difference ΔE ^* _ab for each input ink value.

The fifth calculation unit 135 compares the representative value ΔE calculated by the fourth calculation unit 134 with a predetermined threshold value V. The threshold value V may be set to correspond to, for example, a color difference that may occur even if color conversion is performed using the same ICC profile, or a color difference that is comparable to a measurement error that may occur during color measurement.

The sixth calculation unit 136 determines that the first ICC profile and the second ICC profile are the same or similar when the representative value ΔE is less than or equal to the threshold V, and when the representative value ΔE is greater than the threshold V In this case, it is determined that the first ICC profile and the second ICC profile are dissimilar. Here, when the representative value ΔE is "0", the first ICC profile and the second ICC profile are the same. On the other hand, if the representative value ΔE is greater than "0" and less than or equal to the threshold value V, the first ICC profile and the second ICC profile are not the same, but are "similar" with no substantial difference in the colors of the printed images. ” is determined to be within the range.

If the determination unit 130 determines that the first ICC profile and the second ICC profile are dissimilar, the first adjustment unit 140 uses the first ICC profile and the second ICC profile to The colors of the two printers 10B are matched. As shown in FIG. 3, the first adjustment section 140 includes a first command section 141, a second command section 142, a third command section 143, a fourth command section 144, and a data transmission section 145. There is.

The data transmitter 145 transmits preset input image data and input ICC profile to the second printer 10B. The input image data here is CMYK ink value data. The input ICC profile is a preset ICC profile, and is not particularly limited.

The first command unit 141 commands the color conversion module 43 of the second printer 10B to perform the first color conversion process. In the first color conversion process, the CMYK ink values of the input image data are converted into L ^* a ^* b ^* values using the A2B table of the input ICC profile.

The second command unit 142 commands the color conversion module 43 of the second printer 10B to perform the second color conversion process. In the second color conversion process, the L ^* a ^* b ^* values generated based on the command from the first command unit 141 are converted into CMYK ink values using the B2A table of the first ICC profile. In the following, the CMYK ink values generated by the second color conversion process will be referred to as C1M1Y1K1 ink data.

The third command unit 143 commands the color conversion module 43 of the second printer 10B to perform a third color conversion process. In the third color conversion process, the C1M1Y1K1 ink data generated based on the command from the second command unit 142 is converted into L ^* a ^* b ^* values using the A2B table of the first ICC profile. This L ^* a ^* b ^* value is the color range that can be reproduced by the first printer 10A.

The fourth command unit 144 commands the color conversion module 43 of the second printer 10B to perform a fourth color conversion process. In the fourth color conversion process, the L ^* a ^* b ^* value generated by the color conversion module 43 based on the command from the third command unit 143 is converted into a CMYK ink value using the B2A table of the second ICC profile. Ru. Hereinafter, the CMYK ink values generated by the fourth color conversion process will be referred to as C2M2Y2K2 ink data.

The second adjustment unit 150 adjusts the color development of the second printer 10B for each ink color when the determination unit 130 determines that the first ICC profile and the second ICC profile are the same or similar. The second adjustment section 150 includes a test chart printing section 151 , a colorimetry command section 152 , a data reception section 153 , a correction table creation section 154 , and a correction command section 155 .

The test chart printing unit 151 instructs the first printer 10A and the second printer 10B to print a predetermined test chart. Details of the test chart will be described later.

The color measurement command unit 152 controls the color measurement device 190 to measure the color values of the test chart printed by the first printer 10A and the color values of the test chart printed by the second printer 10B, respectively. The data receiving unit 153 receives data on color values measured by the colorimeter 190.

The correction table creation unit 154 calculates the ink ejection amount of the second printer 10B based on the difference between the color value data of the test chart produced by the first printer 10A and the color value data of the test chart produced by the second printer 10B. Create a correction table to be corrected. Creation of this correction table will be described later. The correction command section 155 instructs the second printer 10B to correct the ejection amount of each ink of the second printer 10B based on the correction table created by the correction table creation section.

The configuration of the control device 103 is also not particularly limited. The control device 103 includes, for example, an interface (I/F) that receives print data etc. from an external device such as a host computer, a central processing unit (CPU) that executes instructions of a control program, and a central processing unit (CPU) that executes instructions of a control program. It includes a ROM (read only memory) that stores a program to be executed, a RAM (random access memory) that is used as a working area to expand the program, and a storage device such as a memory that stores programs and various data.

The colorimeter 190 is configured to be able to measure color values and density values of a printed image. The colorimeter 190 is, for example, a spectral spectrophotometer that can measure the intensity of light for each wavelength. The colorimeter 190 is communicably connected to the color matching device 100 and is controlled by the color matching device 100. Further, the colorimeter 190 transmits colorimetric data to the color matching device 100.

Below, a process of making the color development of the second printer 10B closer to that of the first printer 10A using the color matching system 200 according to the present embodiment will be described.

Differences in color development between multiple inkjet printers are mainly caused by the following factors.
(a) Differences in ink, ink heads, and recording media (b) Differences in ICC profiles (c) Differences in image processing other than ICC profiles (d) Individual differences in inkjet printers and changes over time

In the color matching system 200 according to the present embodiment, after aligning the condition (a), the ICC profile of the first printer 10A (first ICC profile) and the ICC profile of the second printer 10B (second ICC profile) are set. ) are different, color matching of the second printer 10B is performed using the first ICC profile and the second ICC profile. However, even if the ICC profile of the first printer 10A and the ICC profile of the second printer 10B are different, if the representative value ΔE of the color difference between the two ICC profiles is equal to or less than the predetermined threshold V, then the Color matching using the first ICC profile and the second ICC profile is not performed. If the ICC profile of the first printer 10A and the ICC profile of the second printer 10B are the same, or if the representative value ΔE of the color difference between the two ICC profiles is less than or equal to the predetermined threshold V, the Perform color matching (single color matching).

Normally, color matching using an ICC profile and monochrome color matching are not used together as each is effective on its own, but for example, after performing color matching using an ICC profile, the color development may change due to aging of the printer. In some cases, further monochromatic color matching may be performed.

FIG. 4 is a flowchart illustrating the process of determining the sameness and similarity of ICC profiles by the color matching apparatus 100. As shown in FIG. 4, the ICC profile identity/similarity determination includes steps S01 to S07 and step S08 or S09.

In step S01, the first ICC profile is read from the first printer 10A and temporarily stored in the color matching device 100. In step S02, the second ICC profile is read from the second printer 10B and temporarily stored in the color matching device 100. The order of step S01 and step S02 may be reversed.

In step S03, CMYK ink values (input ink values) are input into the A2B table of the first ICC profile, and L ^* a ^* b ^* values are calculated for each input ink value. In step S04, CMYK ink values are input into the A2B table of the second ICC profile, and L ^* a ^* b ^* values are calculated for each input ink value. The order of step S03 and step S04 may be reversed. Moreover, after step S01 and step S03 are executed, step S02 and step S04 may be executed. Alternatively, step S01 and step S03 may be executed after step S02 and step S04 are executed.

In step S05, the color difference ΔE ^* _ab between the color value calculated in step S03 and the color value calculated in step S04 is calculated for each input ink value. In step S06, the average value ΔE is calculated from the color difference ΔE ^* _ab for each input ink value.

In step S07, the average value ΔE of the color difference ΔE ^* _ab calculated in step S06 is compared with a predetermined threshold value V. Then, when the average value ΔE of the color difference ΔE ^* _ab is equal to or less than the threshold value V, it is determined that the first ICC profile and the second ICC profile are the same or similar. In this case, the result of step S07 is "YES". Further, if the average value ΔE of the color difference ΔE ^* _ab is larger than the threshold value V, it is determined that the first ICC profile and the second ICC profile are dissimilar. In this case, the result of step S07 is "NO".

If the result of step S07 is YES, the step proceeds to step S08. In step S08, a command to adjust the color production of the second printer 10B for each ink color is selected. On the other hand, if the result of step S07 is NO, the step proceeds to step S09. In step S09, a command to perform color matching of the second printer 10B using the first ICC profile and the second ICC profile is selected.

As described above, color differences between a plurality of inkjet printers may be due to differences in set ICC profiles or may be due to other causes. If the cause of the color difference is a difference in ICC profiles, it is effective to perform color matching using the ICC profiles. In such cases, it is often impossible to match the colors even if adjustments are made for each ink color. Conversely, if the cause of the color difference is a cause other than the difference in ICC profiles, it is efficient to perform color matching for each ink color. As described above, the color matching device 100 according to the present embodiment has a function of determining whether or not the cause of the color difference includes a difference in ICC profile, and when the cause of the color difference includes a difference in the ICC profile, Select color matching using ICC profile. Furthermore, if the cause of the color difference is a cause other than the difference in ICC profiles, monochromatic color matching is selected. Therefore, according to the color matching apparatus 100 according to the present embodiment, an efficient color matching method can be selected depending on the cause of the color difference.

Below, a method of monochromatic color matching and a method of color matching using an ICC profile will be explained. FIG. 5 is a flowchart showing the flow of monochromatic color matching. In the ICC profile identity/similarity determination in FIG. 4, if it is determined that the first ICC profile and the second ICC profile are the same or similar (proceeding to step S08), the second printer 10B Color matching is performed for each ink color. As shown in FIG. 5, monochromatic color matching is performed through steps S11 to S18.

In step S11, the first printer 10A prints a test chart based on a command from the color matching device 100. In step S12, the second printer 10B prints a test chart based on a command from the color matching device 100. The test chart printed by the first printer 10A and the test chart printed by the second printer 10B are based on the same print image data. Note that step S11 and step S12 may be performed in reverse order or may be performed simultaneously.

FIG. 6 is a plan view schematically showing an example of the test chart T. As shown in FIG. 6, the test chart T is configured such that 21 test patches P1 to P21 are lined up in the main scanning direction Y. The 21 test patches P1 to P21 are test patches formed by changing the amount of ink ejected (ink weight). The 21 test patches P1 to P21 are formed in different areas on the recording medium 5, and are arranged so as not to overlap each other. The test patches P1 to P21 are arranged in the order of P1, P2, . . . P21 from the left. Further, one test chart T is composed of four regions colored with four different colors of ink. The above four areas are lined up in the front-back direction. In this embodiment, the four colors of ink are, in order from the rear, cyan ink, magenta ink, yellow ink, and black ink. Note that the arrangement of the four colors of ink is not particularly limited.

As shown in FIG. 6, identification codes N1 to N21 are printed behind the 21 test patches P1 to P21, respectively. Identification codes N1 to N21 correspond to ink ejection amounts (ink weights) in test patches P1 to P21 formed in front of them, respectively. The 21 identification codes N1 to N21 are, in order from N1, 0, 5, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, 60, 65, 70, 75, 80, 85, 90, 95, 100 are printed on it. The unit of the identification codes N1 to N21 is %. The numerical values [%] of the identification codes N1 to N21 are the ratios to the maximum value of the ink ejection amount (ink weight) ejected from the first ink head 30A to the fourth ink head 30D. For example, in printing the test patch P1, cyan ink, magenta ink, yellow ink, and black ink are each ejected at 0% of the maximum ink weight. In printing the test patch P2, cyan ink, magenta ink, yellow ink, and black ink are each ejected at 5% of the maximum ink weight. Similarly, the ratio of ink weight to the maximum value increases by 5% toward the right test patch, and in test patch P21, the maximum value (ie, 100%) of ink weight is ejected.

As shown in FIG. 5, in step S13 following step S12, the color density of the test chart (hereinafter referred to as first test chart T1) printed by the first printer 10A is measured. This colorimetry is performed by the colorimeter 190 based on a command from the color matching device 100. In this embodiment, the printed first test chart T1 is set in the measurement area of the colorimeter 190 by the user. In step S14, the result of colorimetry of the first test chart T1 by the colorimeter 190 is transmitted to the color matching device 100. In step S15, the color of the test chart (hereinafter referred to as second test chart T2) printed by the second printer 10B is measured in the same manner as in step S13. In step S16, similarly to step S14, the result of colorimetry of the second test chart T2 by the colorimeter 190 is transmitted to the color matching device 100.

In step S17, a correction table is created to correct the ink ejection amount of the second printer 10B based on the difference between the color density data of the first test chart T1 and the color density data of the second test chart T2. Created. The correction table is created, for example, so that the color density of the first test chart T1 and the color density of the second test chart T2 match. A correction table is created for each ink color. Here, the ink value corresponds to the ink ejection amount of the test patches P01 to P21 on the test chart T. The color density corresponds to the color density measured by the colorimeter 190 for each of the test patches P1 to P21.

In step S18, the monochromatic color matching module 42 of the second printer 10B corrects the ejection amount of each ink of the second printer 10B based on the correction table. Through these steps S11 to S18, monochrome color matching of the second printer 10B is performed. After step S18, it is preferable that the second test chart T2 after the correction is printed by the second printer 10B, and the result of the correction is confirmed. Furthermore, if the results of the correction are insufficient, steps similar to steps S11 to S18 may be performed again.

Note that in this embodiment, the work other than setting the first test chart T1 and the second test chart T2 to the colorimeter 190 was performed automatically according to instructions from the color matching device 100, but some of the work was performed manually. May be implemented. For example, the color measurement of the first test chart T1 and the second test chart T2 and the creation of the correction table may be performed by a user using external equipment. Other operations do not necessarily need to be performed automatically. Further, in this embodiment, the first test chart T1 and the second test chart T2 are set in the colorimeter 190 by the user, but the setting may be done automatically. The first printer 10A and the second printer 10B may each include a colorimeter capable of measuring the color of the first test chart T1 and the second test chart T2.

If the result of step S07 in FIG. 4 is NO and the process advances to step S09, color matching of the second printer 10B is performed by color conversion using the first ICC profile and the second ICC profile. . FIG. 7 is a flowchart showing the flow of color matching using the ICC profile. As shown in FIG. 7, color matching using the ICC profile includes steps S21 to S26.

In step S21, preset input image data and input ICC profile are transmitted from the color matching device 100 to the second printer 10B. The input image data is CMYK ink value data.

In the following step S22, the first color conversion process is executed by the color conversion module 43 of the second printer 10B. In the first color conversion process, the CMYK ink values of the input image data are converted into L ^* a ^* b ^* values using the A2B table of the input ICC profile.

In step S23, the second color conversion process is executed by the color conversion module 43 of the second printer 10B. In the second color conversion process, the L ^* a ^* b ^* value generated in step S22 is converted into C1M1Y1K1 ink data using the B2A table of the first ICC profile.

In step S24, the third color conversion process is executed by the color conversion module 43 of the second printer 10B. In the third color conversion process, the C1M1Y1K1 ink data generated in step S23 is converted into L ^* a ^* b ^* values using the A2B table of the first ICC profile. This L ^* a ^* b ^* value is the color range that can be reproduced by the first printer 10A.

In step S25, the fourth color conversion process is executed by the color conversion module 43 of the second printer 10B. In the fourth color conversion process, the L ^* a ^* b ^* value generated in step S24 is converted into C2M2Y2K2 ink data using the B2A table of the second ICC profile.

In step S26, the image is printed by the second printer 10B based on the C2M2Y2K2 ink data. During printing, C2M2Y2K2 ink data is subjected to halftone processing and rasterization processing. Through the processing in steps S21 to S26, the color of the image printed by the second printer 10B is adjusted to match the color of the image printed by the first printer 10A.

The result of color matching by the second printer 10B is confirmed by the image printed in step S26. Therefore, the input image data is preferably image data of the test chart T. The color values of the image printed in step S26 may be checked in the same manner as in steps S11 to S18, for example.

As described above, the color matching method for an inkjet printer according to this embodiment includes a determination process and an adjustment process. In the determination step, the first ICC profile used in the first printer 10A and the second ICC profile used in the second printer 10B are compared, and the first ICC profile and the second ICC profile are compared. It is determined whether they are the same or similar. In the adjustment step, if it is determined that the first ICC profile and the second ICC profile are the same or similar, the color development of the second printer 10B is adjusted for each ink color.

According to this method, it is possible to avoid the inefficient work of color matching using ICC profiles when the color difference is not due to a difference in ICC profiles. Therefore, color matching between multiple printers can be performed efficiently.

Furthermore, in the present embodiment, if the first ICC profile and the second ICC profile are determined to be dissimilar in the determination step, the first ICC profile and the second ICC profile are determined to be dissimilar in the adjustment step. to perform color conversion and color matching for the second printer 10B. According to this method, when the color difference is due to a difference in the ICC profile, it is possible to avoid a situation where color matching is performed for each ink color and color matching cannot be performed as a result.

In this embodiment, the determination step includes steps S03 to S07 in FIG. In step S03, each ink value is input into the A2B table of the first ICC profile, and a color value is calculated for each input ink value. In step S04, each ink value is input into the A2B table of the second ICC profile, and a color value is calculated for each input ink value. In step S05, the color difference ΔE ^* _ab between the color value calculated in step S03 and the color value calculated in step S04 is calculated for each input ink value. In step S06, a representative value ΔE of the color difference ΔE ^* _ab for each input ink value is calculated based on the color difference ΔE ^* _ab for each input ink value calculated in step S05. Here, the representative value ΔE is the average value of the color difference ΔE ^* _ab for each input ink value. In step S07, the representative value ΔE calculated in step S06 is compared with a predetermined threshold V.

The determination process includes step S08 or S09 depending on the result of step S07. In step S07, if the representative value ΔE is less than or equal to the threshold V, it is determined that the first ICC profile and the second ICC profile are the same or similar (in case of YES). Further, in step S07, if the representative value ΔE is larger than the threshold V, it is determined that the first ICC profile and the second ICC profile are dissimilar (in case of NO).

According to this determination step, it is possible to reliably determine whether the first ICC profile and the second ICC profile are the same or similar. Furthermore, if the average value is used as the representative value of the color difference for each input ink value, it is possible to accurately determine the similarity of the ICC profiles, and the load on the color matching device 100 related to calculations does not become excessive.

(Modified example)
The embodiments described above can be suitably implemented with some modifications. For example, in one preferred variation, whether the first ICC profile and the second ICC profile are the same or similar is determined based on the ink value difference. In this modification, the determination process includes the following first to sixth steps.

In the first step, each color value is input into the B2A table of the first ICC profile, and an ink value is calculated for each input color value (hereinafter referred to as input color value). In the second step, each color value is input into the B2A table of the second ICC profile, and an ink value is calculated for each input color value. In the third step, the ink value difference between the ink value calculated in the first step and the ink value calculated in the second step is calculated for each input color value. In the fourth step, a representative value of the ink value difference for each input color value is calculated based on the ink value difference for each input color value calculated in the third step. The representative value is, for example, the average value of ink value differences for each input color value. In the fifth step, the representative value calculated in the fourth step is compared with a predetermined threshold value. In the sixth step, if the representative value is less than or equal to the threshold value, it is determined that the first ICC profile and the second ICC profile are the same or similar, and if the representative value is greater than the threshold value, the first ICC profile It is determined that the profile and the second ICC profile are dissimilar. That is, this modification differs from the above-described embodiment in that the ink value is obtained by inputting the color value to the ICC profile. Also by such a method, it is possible to determine whether the first ICC profile and the second ICC profile are the same or similar.

A preferred embodiment has been described above. However, the color matching system disclosed herein is not limited to the embodiments described above. For example, the method of monochromatic color matching and the method of color matching using ICC profiles described above are merely examples, and may be implemented by other suitable methods. For example, the creation of a correction table for monochromatic color matching may be performed based on visual perception rather than color values measured by a colorimeter.

Further, for example, in the above-described embodiment, the threshold value V to be compared with the representative value ΔE of the color difference ΔE ^* _ab for each input ink value is not “0”, but may be “0”. In this case, in step S07 of FIG. 4, if the representative value ΔE is "0", it is determined that the first ICC profile and the second ICC profile are the same. Further, if the representative value ΔE is larger than "0", it is determined that the first ICC profile and the second ICC profile are not the same. If the first ICC profile and the second ICC profile are not the same, color matching is performed using the ICC profile. Monochromatic color matching is performed only when the first ICC profile and the second ICC profile are the same. According to this method, since the ICC profiles match, color matching is reliable. Note that the same applies to the method of calculating ink value differences by inputting color values.

Also, for example, the difference comparison result between the A2B table of the first ICC profile and the A2B table of the second ICC profile, and the difference comparison result between the B2A table of the first ICC profile and the B2A table of the second ICC profile. It may be determined comprehensively whether the first ICC profile and the second ICC profile are the same or similar using the difference comparison results.

Further, in the embodiment described above, the representative value ΔE of the color difference ΔE ^* _ab for each input ink value is the average value of the color difference ΔE ^* _ab for each input ink value, but this may not be the case. For example, the representative value ΔE of the color differences ΔE ^* _ab for each input ink value may be the maximum value of the color differences ΔE ^* _ab for each input ink value. This method also makes it possible to accurately determine whether ICC profiles are similar or dissimilar. The same applies to the method of inputting color values and calculating ink value differences.

Furthermore, in the embodiments described above, the color difference ΔE ^* _ab is calculated for each input ink value, but the invention is not limited thereto. The color difference ΔE ^* _ab may be calculated for each grid point of the A2B table, for example. Similarly, in the case of the method of calculating the ink value difference by inputting color values, the ink value difference may be calculated for each grid point of the B2A table.

In the embodiments described above, the determination and color matching were performed automatically except for some operations, but they may also be performed manually by the user. There is no particular limitation on whether each step is performed automatically or manually.

Further, in the color matching device 100 described above, the first ICC profile is acquired from the inkjet printer connected to the first communication port 101 and stored in the first storage unit 121; It may be a stored reference ICC profile. Therefore, the reference may be mere data rather than other actual inkjet printers.

Unless otherwise specified, the embodiments described above do not limit the present invention.

10A 1st printer (1st inkjet printer)
10B 2nd printer (2nd inkjet printer)
100 Color matching device 101 First communication port (other communication port)
102 Second communication port (communication port)
103 Control device 110 Acquisition unit 120 Storage unit 130 Determination unit 131 First calculation unit 132 Second calculation unit 133 Third calculation unit 134 Fourth calculation unit 135 Fifth calculation unit 136 Sixth calculation unit 140 First adjustment unit 150 Second Adjustment unit 190 Colorimeter 200 Color matching system ΔE ^* _ab color difference ΔE Representative value of color difference (average value)
V Threshold T Test chart

Claims (13)

A method of color matching a second inkjet printer based on a first inkjet printer, the method comprising:
A first ICC profile used in the first inkjet printer and a second ICC profile used in the second inkjet printer are compared, and the first ICC profile and the second ICC profile are compared. a determination step of determining whether they are the same or similar;
If it is determined in the determination step that the first ICC profile and the second ICC profile are the same or similar, the color development of the second inkjet printer is adjusted for each ink color, and in the determination step If the first ICC profile and the second ICC profile are determined to be dissimilar, the first ICC profile and the second ICC profile are used to control the coloring of the second inkjet printer. an adjustment process to adjust;
including;
The step of adjusting color development of the second inkjet printer using the first ICC profile and the second ICC profile in the adjustment step,
a first process of converting ink values of input image data into color values using an A2B table of a preset input ICC profile;
a second process of converting the color value generated in the first process into ink data using a B2A table of the first ICC profile;
a third process of converting the ink data generated in the second process into color values using an A2B table of the first ICC profile;
a fourth process of converting the color value generated in the third process into ink data using a B2A table of the second ICC profile;
including,
How to match colors in an inkjet printer. The determination step includes:
a first step of inputting ink values into the A2B table of the first ICC profile, and calculating a color value for each input ink value;
a second step of inputting ink values into the A2B table of the second ICC profile, and calculating a color value for each of the input ink values;
a third step of calculating a color difference between the color value calculated in the first step and the color value calculated in the second step for each of the input ink values;
a fourth step of calculating a representative value of the color difference for each ink value based on the color difference for each ink value calculated in the third step;
a fifth step of comparing the representative value calculated in the fourth step with a predetermined threshold;
If the representative value is less than or equal to the threshold, it is determined that the first ICC profile and the second ICC profile are the same or similar; if the representative value is greater than the threshold, the first ICC profile is determined to be the same or similar; a sixth step of determining that the ICC profile of and the second ICC profile are dissimilar;
including,
The color matching method for an inkjet printer according to claim 1. the threshold is zero;
In the sixth step, if the representative value is zero, it is determined that the first ICC profile and the second ICC profile are the same, and if the representative value is greater than zero, the first ICC profile and the second ICC profile are determined to be the same. determining that the first ICC profile and the second ICC profile are non-identical;
The color matching method for an inkjet printer according to claim 2. The representative value is an average value of color differences for each ink value,
The color matching method for an inkjet printer according to claim 2 or 3. The representative value is the maximum value of the color differences for each ink value,
The color matching method for an inkjet printer according to claim 2 or 3. The determination step includes:
A first step of inputting color values into the B2A table of the first ICC profile and calculating an ink value for each of the input color values;
a second step of inputting color values into the B2A table of the second ICC profile and calculating an ink value for each of the input color values;
a third step of calculating an ink value difference between the ink value calculated in the first step and the ink value calculated in the second step for each of the input color values;
a fourth step of calculating a representative value of the ink value difference for each color value based on the ink value difference for each color value calculated in the third step;
a fifth step of comparing the representative value calculated in the fourth step with a predetermined threshold;
If the representative value is less than or equal to the threshold, it is determined that the first ICC profile and the second ICC profile are the same or similar; if the representative value is greater than the threshold, the first ICC profile is determined to be the same or similar; a sixth step of determining that the ICC profile of and the second ICC profile are dissimilar;
including,
The color matching method for an inkjet printer according to claim 1. the threshold is zero;
In the sixth step, if the representative value is zero, it is determined that the first ICC profile and the second ICC profile are the same, and if the representative value is greater than zero, the first ICC profile and the second ICC profile are determined to be the same. determining that the first ICC profile and the second ICC profile are non-identical;
The color matching method for an inkjet printer according to claim 6. The representative value is an average value of ink value differences for each color value,
The color matching method for an inkjet printer according to claim 6 or 7. The representative value is the maximum value of the ink value differences for each color value,
The color matching method for an inkjet printer according to claim 6 or 7. A communication port configured to connect to an inkjet printer,
a control device connected to the communication port;
Equipped with
The control device includes:
a storage unit storing a first ICC profile;
an acquisition unit that reads a second ICC profile used in the inkjet printer connected to the communication port;
a determination unit that compares the first ICC profile and the second ICC profile and determines whether the first ICC profile and the second ICC profile are the same or similar;
If the determination unit determines that the first ICC profile and the second ICC profile are dissimilar, the first ICC profile and the second ICC profile are used to connect the communication port to the communication port. An adjustment unit that performs color matching of the connected inkjet printer,
Equipped with
The adjustment section is
a first command unit that converts ink values of input image data into color values according to an A2B table of a preset input ICC profile;
a second command unit that converts the color value generated based on the command of the first command unit into ink data using a B2A table of the first ICC profile;
a third command unit that converts the ink data generated based on the command of the second command unit into a color value using an A2B table of the first ICC profile;
a fourth command unit that converts the color value generated based on the command of the third command unit into ink data using a B2A table of the second ICC profile;
It is equipped with
Color matching device for inkjet printers. configured to be connectable to an inkjet printer and comprising another communication port connected to the control device,
The control device includes another acquisition unit that reads an ICC profile used in the inkjet printer connected to the other communication port,
The storage unit is configured to store the ICC profile read by the other acquisition unit as the first ICC profile.
The color matching device for an inkjet printer according to claim 10. The determination unit includes:
a first calculation unit that inputs ink values into the A2B table of the first ICC profile and calculates a color value for each of the input ink values;
a second calculation unit that inputs ink values into the A2B table of the second ICC profile and calculates a color value for each of the input ink values;
a third calculation unit that calculates a color difference between the color value calculated by the first calculation unit and the color value calculated by the second calculation unit for each of the input ink values;
a fourth calculation unit that calculates a representative color difference value for each ink value based on the color difference for each ink value calculated by the third calculation unit;
a fifth calculation unit that compares the representative value calculated by the fourth calculation unit with a predetermined threshold;
If the representative value is less than or equal to the threshold, it is determined that the first ICC profile and the second ICC profile are the same or similar; if the representative value is greater than the threshold, the first ICC profile is determined to be the same or similar; a sixth calculation unit that determines that the ICC profile of and the second ICC profile are dissimilar;
It is equipped with
The color matching device for an inkjet printer according to claim 10 or 11. The determination unit includes:
a first calculation unit that inputs color values into the B2A table of the first ICC profile and calculates an ink value for each of the input color values;
a second calculation unit that inputs color values into the B2A table of the second ICC profile and calculates an ink value for each of the input color values;
a third calculation unit that calculates an ink value difference between the ink value calculated by the first calculation unit and the ink value calculated by the second calculation unit for each of the input color values;
a fourth calculation unit that calculates a representative value of the ink value difference for each color value based on the ink value difference for each color value calculated by the third calculation unit;
a fifth calculation unit that compares the representative value calculated by the fourth calculation unit with a predetermined threshold;
If the representative value is less than or equal to the threshold, it is determined that the first ICC profile and the second ICC profile are the same or similar; if the representative value is greater than the threshold, the first ICC profile is determined to be the same or similar; a sixth calculation unit that determines that the ICC profile of and the second ICC profile are dissimilar;
It is equipped with
The color matching device for an inkjet printer according to claim 10 or 11.

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