JP2013236335A - Profile creation device and method, color conversion apparatus and method, program and print system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To create a profile which allows color conversion while reducing visibility of streaks of a printed matter.SOLUTION: The profile creation device includes: K value reduction means (142) for limiting the total amount of a coloring material used for forming a printed matter by means of a printer within a predetermined limit value, reducing an output K value of a first total amount limitation profile defining the conversion relationship of input CMYK values and first output CMYK values so that a color gamut as wide as possible is obtained in the range of color reproduction capability of the printer and setting the K value after reduction; CMY increase means (144) for increasing CMY values in the range of the amount of a coloring material reduced by K value reduction processing; and second total amount limitation profile creation means (146) for creating a second total amount limitation profile defining the conversion relationship of the input CMYK values into second output CMYK values represented by the K value after reduction, and the CMYK values of the CMY values after CMY increase processing.

Description

  The present invention relates to a color adjustment technique for a printing apparatus, and in particular, a profile creation apparatus and method for creating a color conversion table (profile) used for conversion processing of signal values of color image data, a program, and an image using a profile. The present invention relates to a color conversion apparatus, method, program, and printing system that perform data conversion processing.

  Printing apparatuses such as inkjet printers and offset printers have unique color reproducibility for each model. For this reason, when printing based on image data is performed, color management for managing print colors using a profile (color profile) indicating the color reproducibility of a printing apparatus is performed (see Patent Document 1). For example, as described in Patent Document 1, color space conversion from an RGB color space to a CMYK color space is performed using an ICC profile. The ICC profile is a file that defines the characteristics of the device color space according to the format defined by the International Color Consortium, and is based on the color measurement results of the color chart printed out for each printer. Generated.

  Patent Document 2 discloses a color image signal processing technique applied to four-color printing of cyan (C), magenta (M), yellow (Y), and black (black, K). According to Patent Document 2, three color signals (R, G, B signals) read by a color image input device are converted into four color image output signals (C, M, Y, and black) including black (K). In the color image processing method of converting to K signal), the document reading information is converted into a three-variable color signal (CIE L * a * b * signal) in a uniform color space that is perceptually equal, and on the uniform color space. It is proposed that a UCR (Under Color Removal) rate is determined from the saturation signal of 4 colors, and an image output signal of four colors including black is determined from the UCR rate and a three-variable color signal in a uniform color space.

  That is, the technique of Patent Document 2 automatically determines the UCR rate (the ratio of the usage rate of CMY and K) from the saturation signal of the color (L * a * b *) in the uniform color space of the document. Thus, it is possible to easily and accurately reproduce an image, and to realize an image reproduction in which an unnatural saturation gap does not occur between the achromatic color region and the chromatic color region.

JP 2010-103606 A JP 7-87346 A

  However, the technique disclosed in Patent Document 2 has a problem that, when attention is paid to image quality other than color reproduction, satisfactory image reproduction cannot always be performed.

  In general, a color management system (CMS) is used in the printing site. In the CMS processing, for example, there are target color spaces such as JapanColor2007Coat, sRGB, AdobeRGB, and the device of the printing apparatus so that the colors match the target color space. Convert device color signals in the color space. Therefore, when the device color space includes the target color space (when the color gamut of the printing device is wide including the color gamut of the target color space), the color is saved from the target color space to the device color space. Conversion can be performed.

  On the other hand, it is known that the amount of K ink used by a printing apparatus (synonymous with “printing device”) affects image quality. That is, by using a relatively large amount of K ink compared to CMY, there is an effect that the outline of, for example, black characters or line drawings becomes sharp. Further, since the amount of CMY used is relatively reduced when the amount of K used is increased, there is an effect other than image quality, such as a reduction in the total color material usage and an improvement in color material usage costs. In contrast, reducing the amount of K used relative to CMY generally has the effect of improving graininess.

  Further, when attention is paid to the shadow portion of the target color space (a region having a high density, which may be referred to as “SD portion” hereinafter), the amount of K used in the SD portion may have a significant effect on the image quality. In particular, in a single-pass inkjet printer that prints on a medium in a single scan (drawing scan), a nozzle failure (ejection bend or non-ejection) occurs in the nozzle group constituting the nozzle array of the line head. As a result, uneven stripes occur in the area handled by the nozzle, resulting in a fatal image defect. When CMYK ink is used as the color material, K has the strongest contrast. Therefore, when the amount of K used is large, unevenness caused by K has strong visibility, which is particularly problematic.

  The present invention has been made in view of such circumstances, and a profile creation apparatus and method, a color conversion apparatus and method, a program, and a program that enable color conversion processing that can reduce the visibility of unevenness in printed matter, and An object is to provide a printing system.

  In order to solve the above-described problems, a profile creation apparatus according to the present invention is a color of a printing apparatus that performs printing using cyan (C), magenta (M), yellow (Y), and black (K) color materials. A profile creation device for creating a profile used for color conversion processing for adjusting expression, wherein the total amount of color materials used when forming a printed matter by a printing device is limited to a predetermined limit value, and the printing device The first total amount storing the first total amount restriction profile in which the conversion relationship between the input CMYK value and the first output CMYK value is defined so that the color gamut is as wide as possible within the range of the color reproduction capability of A limit profile storage unit, a K value reduction processing unit that determines the K value after reduction by reducing the output K value of the first total amount limit profile, and a CMY value as the K value is reduced by the K value reduction processing unit. CMY increase ratio determining means for determining an increase ratio of CMY when added, and a range of color material amounts reduced by K value reduction processing of the K value reduction processing means based on CMY increase ratio data defining the CMY increase ratio The CMY increase processing means for increasing the CMY value, and the input CMYK value with respect to the input CMYK value and the second CMY value represented by the CMYK value of the CMY value after the CMY increase process by the CMY increase processing means. And a second total amount restriction profile creation processing unit that generates a second total amount restriction profile that associates the output CMYK values and defines the conversion relationship between the input CMYK values and the second output CMYK values.

  According to the present invention, the first total amount restriction profile restricts the total amount of color material within the range of the restriction value, and the input CMYK value and the output so that the color reproduction capability of the printing apparatus can be maximized. A relationship with the CMYK value (first output CMYK value) is defined. The output CMYK value in the first total amount restriction profile is corrected by the K value reduction process and the CMY increase process, and a second total quantity restriction profile is created. In the second total amount restriction profile, the K value that is particularly conspicuous is reduced, and CMY is increased in the range of the K color material amount that is reduced.

  Of the four colors of CMYK, K is most easily visually recognized as being uneven in the shadow portion (low brightness portion). Therefore, by reducing the K value, it is possible to reduce the visibility of the uneven stripe (particularly in the shadow portion). In addition, the density (color reproduction range) that has decreased due to the reduction of the K value is restored as much as possible by the CMY increase process. For this reason, by performing printing with a printing apparatus based on the CMYK signal obtained by converting the CMYK signal value using the second total amount restriction profile, it is possible to reduce the visibility of the uneven stripe while ensuring the color reproduction range. can do.

  Other aspects of the invention will become apparent from the description and drawings.

  According to the present invention, it is possible to perform color conversion processing that can reduce the visibility of uneven stripes in printed matter within the range of the total amount of color material. In addition, a required color reproduction range of the printing apparatus can be ensured.

1 is a diagram illustrating an overall configuration of a printing system to which a profile generation device and a color conversion device according to an embodiment of the present invention are applied. Block diagram showing a hardware configuration example of an image processing apparatus Main part block diagram showing functional configuration regarding profile creation function and color conversion processing function in image processing apparatus Flow chart showing a procedure for acquiring learning data of a color predictor Color material total amount restriction profile creation processing flowchart Diagram showing an example of a bar chart A flowchart showing a procedure for acquiring K value-image quality relationship data Main block diagram related to shadow part (SD part) optimization processing Flow chart of SD section optimization process Flow chart of K value reduction processing CMY distribution process flowchart Block diagram showing the configuration of the CMY distribution processing unit Flowchart of creation processing of SD unit optimization total amount restriction profile and SD unit optimization printer profile in image processing apparatus The flowchart which shows the outline | summary of the CMS process in this embodiment Schematic diagram showing the color gamut of the SD section optimized printer profile created in this embodiment

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 is a diagram illustrating an overall configuration of a printing system to which a profile generation apparatus and a color conversion apparatus according to an embodiment of the present invention are applied. The printing system 10 generates image data indicating the content of an image to be printed (hereinafter referred to as “original image data”, “submitted image data”, or “submitted data”). A computer 12, a profile creation device that creates a table (profile) for color conversion processing, an image processing device 14 that functions as a color conversion device that performs color conversion processing using the created profile, and a colorimeter 16 A printing machine 18 as a color image output device, a controller 20 for controlling the printing machine 18, and a management computer 22. The front-end computer 12, the image processing apparatus 14, the controller 20, and the management computer 22 are connected to a communication network 24 such as a LAN (Local Area Network).

  Although not shown in FIG. 1, in addition to the configuration shown in the figure, the communication network 24 performs printing using a plate making apparatus such as a plate recorder and its controller, and a printing plate produced by the plate making apparatus. You can also connect multiple machines and computers. The number of front-end computers 12, management computers 22, printing machines 18, plate making apparatuses, etc. included in this system is not particularly limited.

  For example, the functions of the front-end computer 12, the image processing apparatus 14, the controller 20, and the management computer 22 can be realized by a single computer, or can be realized by a plurality of computers. These functions may be realized by integrating the image processing apparatus 14 and the controller 20 with a single computer, or the functions of the image processing apparatus 14 may be installed in the management computer 22.

  The front-end computer 12 is used for editing various types of image parts such as characters, figures, patterns, illustrations, and photographic images to be printed and laying them out on a printing surface. Original image data as print source image data is generated by an editing operation by the front-end computer 12 or the like. The document image data generated by the front end computer 12 is transferred to the image processing device 14 and the controller 20. The means for generating the document image data is not limited to the form created by the front-end computer 12, but may be created by another computer, an image creating / editing apparatus, etc. (not shown). The document image data can be input to the image processing device 14 or the controller 20 through the communication network 24 or using a removable medium (external storage medium) such as a memory card.

  The image processing device 14 functions as a profile creation device according to the embodiment of the present invention, and performs color profile generation processing for managing print colors. The image processing device 14 functions as a color conversion device, and rasterizes (RIP processing) original image data for printing (for example, data described in a page description language) generated by the front-end computer 12 or the like. Functions as a means to The image processing apparatus 14 can be realized by a combination of computer hardware and software. The function as the RIP device may be installed in the controller 20 of the printing machine 18.

  The colorimeter 16 is means for measuring the color patch on the color chart printed on a medium such as printing paper, and for example, a spectrophotometer can be used. Information measured by the colorimeter 16 is provided to the image processing device 14. For example, the colorimeter 16 is connected to the image processing apparatus 14 via a wired or wireless communication interface unit (not shown), and measurement data (color patch colorimetric data) by the colorimeter 16 is obtained. It is sent to the image processing device 14. Alternatively, the measurement data may be input to the image processing apparatus 14 using a removable medium (external storage medium) such as a memory card.

  As the printing machine 18, various types of printing machines (synonymous with “printer” and “printing apparatus”) such as a digital printing machine such as an inkjet printer, an offset printing machine, and an electrophotographic printing machine can be adopted. In the case of a printing press using a printing plate, a plate making apparatus such as a plate recorder and its controller, and a printing machine that performs printing using the printing plate created by the plate making apparatus are connected to the communication network 24. The The printing machine 18 or the combination of the printing machine 18 and the controller 20 in this example corresponds to a “printing apparatus”. Further, a combination of a plate making apparatus, its controller, and a printing press using the prepared printing plate can be interpreted as a “printing apparatus”.

  The management computer 22 performs various types of management in the printing system 10. For example, image management and print job management are performed.

  In this example, the front end computer 12, the image processing apparatus 14, the controller 20, and the management computer 22 are illustrated as being connected to a communication network 24 such as a LAN (Local Area Network). Each element does not necessarily have to be connected to the communication network 24.

  FIG. 2 is a block diagram illustrating a hardware configuration example of the image processing apparatus 14. The image processing apparatus 14 of this example is realized using a personal computer (PC). That is, the image processing device 14 includes a PC main body 30, a display device 32, and an input device 34. The PC main body 30 includes a central processing unit (CPU) 41, a memory 42, a hard disk device (HDD) 43 as a storage device for storing and storing various programs and data, an input interface unit 44, and a network connection. A communication interface unit 45, a display control unit 46, and a peripheral device interface unit 47 are provided. The colorimeter 16 is connected to the image processing apparatus 14 via the peripheral device interface unit 47.

  For example, a liquid crystal display or an organic EL display can be used as the display device 32. The display device 32 is connected to the display control unit 46. The input device 34 may employ various means such as a keyboard, a mouse, a touch panel, and a trackball, and may be an appropriate combination thereof. In this example, a keyboard and a mouse are used as the input device 34. The input device 34 is connected to the input interface unit 44. The display device 32 and the input device 34 function as a user interface (UI). An operator (user) can input various information using the input device 34 while viewing the contents displayed on the screen of the display device 32, and can operate the image processing device 14, the printing machine 18, and the like. . Further, it is possible to grasp (confirm) the state of the system through the display device 32.

  The hard disk device 43 stores various programs and data necessary for image processing. For example, color chart definition data, a profile generation program, an image processing program, a color chart measurement value data group, and the like are stored. When the program stored in the hard disk device 43 is loaded into the memory 42 and executed by the CPU 41, it functions as various means defined by the program.

  In the present embodiment, various programs can be provided by, for example, a computer-readable recording medium such as a CD-ROM in which these programs are recorded. That is, the user purchases a CD-ROM as a recording medium for the program, attaches it to a CD-ROM drive (not shown), reads the program from the CD-ROM, and installs it on the hard disk device 43. Alternatively, program data (signal) sent via the communication network 24 may be received and installed in the hard disk device 43.

  2 may be adopted as the hardware configuration of the management computer 22 and the controller 20 of the printing machine 18 described in FIG. it can. Alternatively, a color separation device equipped with the image processing device 14 can be provided.

  FIG. 3 is a principal block diagram showing a functional configuration related to the profile generation function and the color conversion processing function in the image processing apparatus 14. The image processing apparatus 14 includes a color predictor 110 (corresponding to “color predicting unit”), a color material total amount restriction profile creation processing unit 120, and a total amount restriction profile storage unit 122 (corresponding to “first total amount restriction profile storage unit”). , Printer profile creation processing unit 130, printer profile storage unit 132, K value-image quality relation data storage unit 134, target profile storage unit 136, shadow (SD) unit optimization processing unit 140, SD unit optimization total amount restriction profile storage unit 146, an SD unit optimization printer profile creation processing unit 150 (corresponding to “shadow part optimization printer profile creation processing means”), and an SD unit optimization printer profile storage unit 152.

  In addition, the image processing apparatus 14 includes an image input interface unit 160 (corresponding to “image input unit”), a CMS processing unit 162 (corresponding to “color adjustment processing unit”), a total color material amount restriction processing unit that accepts the submitted data 50. 1648 (corresponding to “total color material amount restriction processing means”), and data for outputting image data after color conversion (CMYK data after restriction on the total amount indicated by reference numeral 70) generated through these processing units (162, 164). An output unit 166 is provided.

  The image processing apparatus 14 according to the present embodiment generates an SD unit optimized total amount restriction profile and an SD unit optimized printer profile in which the shadow (SD) unit is optimized, and performs color conversion processing (CMS processing, color matching) on these profiles. This is used for color conversion of the submitted data 50 using the total material amount limiting process. Each unit shown in FIG. 3 can be realized by a combination of computer hardware and software (program).

  Hereinafter, functions of each unit will be described.

<< Color Predictor >>
The color predictor 110 is configured by software that predicts an output color (for example, a device-independent value such as L * a * b *) for a CMYK signal input to the printing device (printing machine 18). The color predictor 110 of this example has a forward mapping prediction function that predicts L * a * b * values from CMYK values and an inverse mapping prediction function that calculates CMYK values from L * a * b * values. . Data defining the forward mapping and reverse mapping in the color predictor 110 is generated based on the color chart colorimetric data group obtained by measuring the color chart output by the printing machine 18. In this example, CIE-L * a * b * is used as the color system (color coordinate system) of the device-independent color space, but is not limited to this.

  The color predictor 110 stores a color measurement data group (learning data) obtained by measuring each patch of the color chart output by the printing machine 18 (hereinafter referred to as “color chart color measurement data group storage”). 112), a forward mapping prediction unit 114 (corresponding to “forward mapping prediction means”) that performs an operation of predicting L * a * b * from CMYK according to the forward mapping table generated based on the learning data. And an inverse mapping prediction unit 116 (corresponding to “inverse mapping prediction means”) that performs an operation of performing CMYK prediction from L * a * b * according to an inverse mapping table generated based on learning data.

  Data (mapping table) defining forward mapping and reverse mapping in the color predictor 110 can be created by the following method, for example. FIG. 4 is a flowchart thereof.

  First, color chart data composed of a plurality of color patches (patch groups) defined by changing each CMYK color signal value in 10% increments is created (step S102), and the color chart is printed in accordance with the color chart data. (Printer 18) outputs (step S104). Next, the patch group of the output color chart is measured by a colorimeter (reference numeral 16 in FIG. 1), and the L * a * b * value of each patch is obtained (step S106).

  The colorimetric value is acquired as a value in a device-independent color space, and may be expressed as, for example, a CIE-L * a * b * value (hereinafter referred to as “L * a * b * value” or “Lab value”). Can be used). Of course, other colorimetric values such as CIE-XYZ values and spectral reflectances can also be used.

  In this way, data that summarizes the correspondence between the input values (definition values, CMYK values in this example) and the actual colorimetric values (L * a * b * values in this example) of each color patch of the color chart data (hereinafter referred to as “color values”). , "Input value-colorimetric value relation data") is generated (step S108). The input value of the color patch is defined by a color space (device-dependent color space) depending on the printer 18 as an image output device. For example, in the case of a printer that performs printing in four colors of CMYK, the input value of the color patch is represented by a CMYK value. The color chart colorimetric values are obtained as values in a predetermined device-independent color space defined by the colorimeter 16 (for example, L * a * b * values). For each patch of a number of color patches included in the color chart, relational data of colorimetric values with respect to input values is obtained. A set of input value-colorimetric value relationship data of a large number of color patches is referred to as a “color chart colorimetric value data group” or a “learning data group”. The color chart colorimetric value data (learning data) group is stored and saved in the color chart colorimetric value data group storage unit 112 such as a memory (step S110).

  As a result, for forward mapping, L * a * b * for CMYK in increments of 10% can be calculated. Also, other CMYK values other than CMYK values corresponding to 10% increments can be predicted by using an interpolation calculation or the like. In this case, it is possible to use a physical model such as a Neugebauer model or a Jürniersen modified Neugebauer model without using a simple interpolation operation. By using a physical model, it is possible to perform color prediction with higher accuracy than in the case of performing simple interpolation calculation.

  The inverse mapping is a mapping from a three-dimensional space to a four-dimensional space, and CMYK is not uniquely determined for a certain L * a * b * value. This is because K black by K ink, composite black by CMY color mixture, and a combination of K black and composite black are possible to represent a certain black color.

  Therefore, when the inverse mapping is obtained, the value of K is input as a constraint in advance, and the remaining CMY values are uniquely determined using a nonlinear optimization method such as Newton method, quasi-Newton method, or downhill simplex method. It becomes possible. The K value constraint condition is set by the K value constraint condition setting unit denoted by reference numeral 118 in FIG. The K value constraint condition setting unit 118 allows the operator to designate a desired K value by operating the input device (reference numeral 34 in FIG. 2) from a GUI (graphical user interface) displayed on the display device 32 (see FIG. 2). A configuration may be employed, or a configuration in which the configuration is automatically set in conjunction with the selection of the print mode may be employed.

  In the above example, the patch group corresponding to the learning data for color prediction is defined in increments of 10%, but this is not limited to 10%. If you want to improve color prediction accuracy, you can make it 5% increments, etc. If you want to reduce the measurement man-hours, for example, select priority colors such as skin color and gray (ie make the step size finer), etc. It may be devised to increase the color step size.

<Regarding restrictions on the total amount of color material>
Each signal of CMYK can change the signal value (density) in the range of 0 to 100%. However, as will be described later, if the total percentage of CMYK becomes too large, the recording medium cannot absorb the ink applied in a superimposed manner, and the color reproduction of the patch cannot be accurately performed, or the film characteristics are deteriorated due to excessive ink. May occur, or the paper may bend due to excess ink, causing problems in the conveyance of the medium. To address these issues, if the total percentage of CMYK is greater than a specified upper limit (for example, if the total percentage exceeds 250%), do not create a color patch and do not print the patch. It is preferable to do. In this case, L * a * b * for CMYK of the color patch that is not printed cannot be obtained. However, since this area is unsuitable for printing in the first place, it may not be necessary to obtain L * a * b * data. Many. If the data outside the measurement is necessary for the convenience of the system, it can be obtained by extrapolation or substituted with an appropriate value so that it can be recognized as an error value separately. .

  Note that the color predictor 110 needs to be created separately for each recording medium because the relationship of CMYK-L * a * b * changes if the type of recording medium is different. That is, for each type of recording medium, color chart output and colorimetry are performed, and CMYK-L * a * b * relationship data is generated for each recording medium.

<< Color material total amount restriction profile creation process >>
In general, in inkjet printers and electrophotography, when four color materials are used in the vicinity of their maximum amounts, the recording medium cannot absorb the ink applied in a superimposed manner on the recording medium, and accurate patch color reproduction May not be possible, the film characteristics may be deteriorated due to excess ink, or the paper may bend due to excess ink, causing problems in media conveyance. Therefore, if the mapping table of the color predictor 110 is applied to the CMS process as it is, an excessive color material amount signal may be input to the printing device (printing machine 18). Therefore, a process for limiting the total amount of the color material is necessary.

  For example, the total color material amount restriction processing unit 164 converts the CMYK values so that the total of the four types of CMYK color materials does not exceed 250% (below 250% or less). In this conversion process, a color material total amount limit value (CMYK total upper limit value, 250% as an example) is defined in advance, and conversion is performed so that the reproduction color space is as wide as possible within a range not exceeding the color material total amount limit value. I do. A table created to define the CMYK → CMYK conversion (mapping) of the total color material amount restriction process is a total amount restriction profile (or an SD part optimized total amount restriction profile created by further optimizing the SD part). .

  The color material total amount restriction profile creation processing unit 120 performs a total amount restriction profile (“first total amount” for performing CMYK → CMYK conversion so as not to exceed the color material total amount restriction value set by the color material total amount restriction value setting unit 124. Equivalent to “Restricted Profile”). The total color material amount limit value is determined from the viewpoint of the type of recording medium, required print quality, cost, and the like, and is set by the total color material amount limit value setting unit 124 (see FIG. 3). The operator can designate a desired K value by operating the input device (reference numeral 34 in FIG. 2) from the GUI (graphical user interface) presented on the color material total amount limit value setting unit 124 and the display device 32 (see FIG. 2). A configuration may be adopted, or a configuration in which the setting is automatically performed in conjunction with the selection of the print mode and the paper (recording medium) type may be employed.

  The total amount restriction profile defines, for example, CMYK values after the color material total amount restriction for each CMYK in which the CMYK color space (each axis 0-100%) is changed by 5%. Specifically, when the total color material amount limit value is 250%, for example, for (C, M, Y, K) = (0, 0, 0, 50), the total color material amount is 50%. Yes, since it does not exceed 250% of the total color material amount limit value, (C, M, Y, K) = (0, 0, 0, 50) after conversion. On the other hand, for example, for (C, M, Y, K) = (100, 100, 100, 100), the total color material amount is 400%, which exceeds the color material total amount limit value of 250%. After conversion, (C, M, Y, K) = (50, 50, 50, 100), etc. Here, in limiting the total amount of color material, the K value is fixed and the CMY value is decreased. However, in general, it is more common to use K black more than CMY composite plaques. The amount can be increased by the amount. Therefore, as described above, when conversion is performed so that the color space is as wide as possible, K = 100% is necessarily fixed.

  In the above example, for (C, M, Y, K) = (0, 0, 0, 50), (C, M, Y, K) = (0, 0, 0, 50) after conversion. 50) is set, but the K usage value is reduced to improve the image quality such as graininess so that it falls within the same color range on the device-independent space (ie, L * a * b * is (C, M, Y, K) = (10, 10, 10, 40) or the like may be set by replacing K with CMY (with little change).

  In order to obtain another CMYK that falls within the same color range as (C, M, Y, K) = (0, 0, 0, 50), K = 40 using the inverse mapping prediction function of the color predictor 110. The remaining CMY may be predicted after imposing a constraint condition on K as shown in FIG. In the above example (C, M, Y, K) = (10, 10, 10, 40), it means that CMY predicted (estimated) under the constraint condition of K = 40 was 10% respectively. .

  FIG. 5 is a flowchart of the total color material amount restriction profile creation process. First, a color material total amount limit value is defined (step S122). Among the CMYK values in the CMYK color space, for the CMYK values that exceed the total color material amount limit value, CMYK values that fall within the total color material amount limit value (CMYK after the total amount limit) are determined (step S124). A lookup table that defines the relationship between the input CMYK and the CMYK after the total amount restriction (that is, the total amount restriction profile) is generated (step S126), and the obtained total amount restriction profile is stored in the total amount restriction profile storage unit 122 such as a memory ( Step S128).

  In the above example, the color material total amount limit value is specified as a percentage such as 250%, but the method of specifying the limit value is not limited to the percentage. For example, a mechanism for calculating in advance the volume of the color material for each single color input of C, M, Y, and K as a volume is provided so that the total value of each color material amount (volume) does not exceed a certain limit value. May be. By using the volume which is physical information instead of the percentage, the color material amount can be managed more strictly.

  As described above, when the color material total amount restriction profile creation processing unit 120 performs conversion so that the color space is as wide as possible, K = 100% is necessarily fixed. On the other hand, in the SD unit optimization process described later, the maximum value of K is determined from the viewpoint of image quality without fixing K to 100%. That is, in the SD optimization process, the K value is reduced in order to improve the image quality even at the expense of the density that can be expressed by the printer.

<< Total amount restriction profile >>
The total amount restriction profile created by the total color material amount restriction profile creation processing unit 120 is a profile in which the relationship between the input CMYK and the CMYK after total amount restriction is held as a lookup table (LUT), and is defined using, for example, an ICC profile format. Is done. This total amount restriction profile is created by the color material total amount restriction profile creation processing in the color material total amount restriction profile creation processing unit 120 and is stored in the total amount restriction profile storage unit 122.

<< Printer profile creation process >>
The printer profile creation processing unit 130 receives the color predictor 110 and the total amount restriction profile as input, and creates a printer profile. The printer profile is a color (L * a * b *) printed by CMYK values before color material total amount restriction and CMYK after color material total quantity restriction (hereinafter referred to as “total quantity restriction CMYK1”). ) As a LUT. L * a * b * for the total amount limit CMYK1 can be predicted using the forward mapping prediction function of the color predictor 110.

  If it is determined that the accuracy of the color predictor 110 is not sufficient, a color chart is created again using only the CMYK values defined by the total amount limit CMYK1, and the color chart is measured after printing. Very good. In FIG. 3, the arrow from the color predictor 110 to the printer profile creation processing unit 130 is drawn with a broken line because the color predictor 110 is not necessarily used in the printer profile creation processing step in the printer profile creation processing unit 130. It shows that there is no.

  Note that this printer profile creation processing is not necessary for printing in the present embodiment in a state in which the SD section optimization described later is performed, but it is necessary to perform printing before performing the SD section optimization. Is necessary.

<< Printer profile >>
The printer profile is a device-independent color space such as a color (L * a * b * value) printed by CMYK values before color material total amount limitation and CMYK (total amount limitation CMYK1) after color material total limitation. (Color defined in (1)) as a LUT and is defined using, for example, an ICC profile format. The printer profile is created by the printer profile creation processing unit 130 and stored in the printer profile storage unit 132.

  It can be said that the printer profile represents a pure color reproduction capability in consideration of the influence of the total color material amount restriction process (ink amount restriction) on the combination of the corresponding printing device (printer 18) and the recording medium. That is, the original color reproduction capability of the printing device (the potential color reproduction capability of the printing device) is represented by this printer profile.

  In the present embodiment, an SD unit optimized printer profile having a narrower color gamut than the printer profile is generated from the viewpoint of reducing the non-uniformity visibility of the SD unit.

<< K value-image quality-related data >>
The K value-image quality relationship data stored in the K value-image quality relationship data storage unit 134 is data representing the relationship between the K value to be used and the image quality score (also referred to as image quality index or image quality evaluation value indicating image quality evaluation). is there. The image quality index includes various image quality attribute elements such as graininess and stripe unevenness. Here, an example of stripe unevenness which is particularly problematic in an ink jet printer of a single pass printing method will be described.

  Consider printing a flat net chart (hereinafter referred to as a bar chart) in the direction in which the nozzles of a single-pass inkjet head are aligned (hereinafter referred to as the width direction) for a certain K value. . When the printed bar chart is observed, unevenness occurs at a place printed by a defective nozzle (nozzle in which the printing position is shifted or non-ejection is placed). In addition, the degree of unevenness varies depending on the magnitude of the K value.

  In general, if the K value is decreased, the streak contrast decreases accordingly, and the visibility of the streaks decreases. In addition, if the CMY value is increased with respect to the K value reduction, not only the visibility of the streak is reduced due to the decrease in the K value, but also the CMY ink printed on the defective portion of K plays a role of filling the streak. The contrast of streaks further decreases, and the visibility of streaks also decreases.

  Therefore, the visibility of the stripe unevenness can be reduced by reducing the K value as much as possible and increasing the CMY value as much as possible. However, in order to express the density reduced by the K value reduction as a CMY value, a larger amount of CMY ink is generally required than the reduced K ink amount. -CMY replacement has a limit in terms of ink amount.

  Here, an example of a method of generating K value-image quality relation data will be described.

<Evaluation of bar chart output and image quality score>
K value-image quality relationship data is created by outputting a bar chart created while gradually reducing K from 100% for a certain SD part color, and evaluating the degree of visibility of streaks for each K value To do. As the color of the SD portion, for example, a color corresponding to 100% input of four colors, that is, an input of (C, M, Y, K) = (100, 100, 100, 100) is selected. As described above, since 100% input of four colors is converted by the total amount restriction profile so that the ink amount does not exceed the restriction value, in the above example, (C, M, Y, K) = (50, 50, 50, 100) in advance. Therefore, in this case, the bar chart is (50, 50, 50, 100), (50, 50, 50, 99), (50, 50, 50, 98), (50, 50, 50, 97), (50, 50, 50, 96), etc.

  FIG. 6 shows an example of a bar chart. As shown, K = 100% bar chart 92A, K = 99% bar chart 92B, K = 98% bar chart 92C, K = 97% bar chart 92C, K = 97% on the recording medium 90. Bar chart 92D, K = 96% bar chart 92E... Are printed.

  Next, for each bar of the output bar chart, the visual recognition level of the streak is evaluated, and the streak characteristics with respect to each K value are evaluated, for example, evaluation “C” (streaks are conspicuous), evaluation B (streaks are not conspicuous) , And evaluation A (no streak is visually recognized). In this way, relational data of image quality (evaluation of stripe visual recognition level) with respect to the K value is obtained. Further, the color of each of the bar charts 92A, 92B, 92C,... At this time is measured with L * a * b * (or density) using the colorimeter 16, and the color change due to K reduction is recorded. May be.

  FIG. 7 is a flowchart showing a procedure for acquiring K value-image quality relationship data. First, bar chart data in which the value of K is gradually changed for the color of the SD portion (for example, gray) is created (step S132), and the bar chart is printed on the recording medium by the printer 18 (step S132). S134). The image quality is evaluated for each of the plurality of bar charts having different K values (step S136), and relation data ("K value-image quality relation data") between the K value and the image quality (evaluation result) is generated (step S138). This is stored in the K value-image quality relationship data storage unit 134 such as a memory (step S140).

<Bar chart output and evaluation of image quality score; Conversion example 1>
The bar chart may be created by gradually changing only the K value as described above, but the ink amount corresponding to the reduced K value may be replaced with CMY for output. That is, for example, when outputting a bar chart while keeping the total color material amount (total% value) at 250%, (C, M, Y, K) = (50, 50, 50, 100), (50.33, 50.33) , 50.33, 99), (50.67, 50.67, 5.67, 98), (51, 51, 51, 97), etc. As a result, not only the effect of reducing the K value but also the effect of improving the streaks due to the increase in CMY can be added to the streak characteristics, thereby giving an image quality score.

  Further, in this example, when CMY is increased, each color equal amount is increased, but instead of such an equal amount increase, for example, (50, 53, 50, 97) is specified. You may devise so that it may change to the hue of. For example, if there is a difference in hue between the 100% output color of the corresponding printer and the 100% output color of the target profile described later, CMY is increased so as to approach the hue of the target profile, which will be described later. When the SD part optimization process is performed, a decrease in inclusiveness with respect to the target profile can be minimized.

<Output of bar chart and evaluation of image quality score; Conversion example 2>
The creation of the bar chart and the evaluation of the image quality score may be performed only for four-color 100% input as described above, but also for other inputs of K = 100%, and the K value-image quality relation data. You may make it acquire two or more. For example, (C, M, Y, K) = {(0, 0, 0, 100), (0, 0, 100, 100), (0, 100, 0, 100), (0, 100, 100, 100), (100, 0, 0, 100), (100, 0, 100, 100), (100, 100, 0, 100), (100, 100, 100, 100)} For example, a method of acquiring an image quality score for each input of eight vertices (end points) created by the CMY three-dimensional color space when fixed to% is conceivable. This is useful data when performing an application of changing the amount of reduction of the K value according to the input CMY value when performing the SD unit optimization process described later.

<< Target profile >>
The target profile is a profile in which the relationship between CMYK (or RGB) and L * a * b * is defined in advance, such as Japan Color 2007 Coated, sRGB, AdobeRGB, and is defined using, for example, an ICC profile format. If the user designates the target profile in advance and creates the submission data, the L * a * b * of the device-independent color for CMYK (or RGB) of the submission data can be known. The printing can be performed with the color saved.

  In the embodiment having the configuration shown in FIG. 3, information on a plurality of types of target profiles is stored in the target profile storage unit 136, and information on the target profiles used in the submitted data 50 is referred to.

  A means for acquiring necessary target profile information from the target profile storage unit 136 or a means for acquiring target profile information from the outside corresponds to a “target profile acquisition means”.

<< SD section optimization process >>
Next, the SD unit optimization process will be described. FIG. 8 is a main part block diagram related to the SD part optimization process. In FIG. 8, the same elements as those shown in FIG. The SD unit optimization processing unit 140 receives the total amount restriction profile 182 (corresponding to the “first total amount restriction profile”) as an input, and an SD optimized printer profile 190 (“shadow part” which improves the CMYK value of the SD unit from the viewpoint of image quality. Equivalent to “optimized printer profile”). In the course of this SD unit optimization process, the K value-image quality relationship data 186, the target profile 188, and the color predictor 110 are referred to in some cases.

  As described in the description of the color material total amount restriction profile creation processing unit 120, when the total amount restriction profile 182 is created so that the color space is as wide as possible, the output for an input of K = 100% is necessarily K. = 100%. However, when K = 100%, there are cases where the image quality in the vicinity, in particular, the degree of unevenness, may be poor. Therefore, in the SD portion optimization processing, the maximum value of K is determined from the viewpoint of image quality without fixing K to 100%. That is, the K value is reduced in order to improve the image quality even at the expense of the density that can be expressed by the printer (printer 18).

  FIG. 8 is a flowchart of the SD unit optimization process. In the SD unit optimization process, as shown in FIG. 8, first, a K value reduction process (corresponding to “K value reduction process step”) is performed (step S210), and then a CMY distribution process (“CMY increase process step”). (Corresponding to step S220).

<< K value reduction processing >>
FIG. 9 is a flowchart of the K value reduction process.

<K reduction value determination processing for elements whose total amount restriction profile input value is K = 100%>
In the K value reduction process, first, a K reduction value determination process (hereinafter referred to as a K reduction value determination process) for an element whose input value of the total amount restriction profile 182 is K = 100% is performed (step S212). If the input CMYK of the total amount restriction profile 182 is sampled in increments of 5% for each axis, each axis is sampled at 21 points of 0, 5, 10,..., 100%. Output CMYK with respect to the input of the fourth power (21 ⁴ ) = 1944481 lattice points is defined. Of these, if only K = 100% input is extracted, there are 21 cubed (21 ³ ) = 9261 grid points. Generalizing this input grid point gives (i, j, k, 100) (where i: 0, 5, 10,…, 100, j: 0, 5, 10,…, 100, k: 0, 5, 10,…, 100). At this time, the K value of the output CMYK (represented as “total amount restriction CMYK1”) of the total amount restriction profile before the SD portion optimization processing is 100%. Determining the output K value for each of the 9261 grid points is K reduction value determination processing (step S212).

<K reduction value determination processing; Example 1>
The simplest method for determining the K reduction value is to set the same value as the output K value at all 9261 grid points. For example, K = 90% is set.

  In the K reduction value determination process, information of K value-image quality relationship data (see reference numeral 186 in FIG. 8) may be used. For example, if the image quality score for K = 88% is “A” (no streak is visible) in the K value-image quality relationship data for 100% input of 4 colors as described above, K = 88% is adopted. It is possible to do. As described above, the reduction of the K value has a trade-off relationship between improvement in image quality and decrease in density. Therefore, if K = 88%, the image quality score is “B” if the density is sacrificed and it is considered NG. It is also effective to adopt, for example, K = 94% (in which the streak is inconspicuous) and to suppress the influence of density reduction.

<K Reduction Value Determination Processing; Example 2>
As another example of the K reduction value determination process, different output K values may be set for 9261 points where the input CMYK is (i, j, k, 100). For example, output K = 80% is set for the input of (50, 40, 50, 100), and output K = 90% is set for the input of (80, 90, 80, 100). It is. This means that the output K value is changed with respect to the input CMY value. In this way, for example, when it is desired to ensure that a high density can be output (100, 100, 100, 100), the K value is not reduced so much, and a high density is not required (10, 10). , 10, 100), etc., it is possible to reduce the K value excessively.

  When changing the output K value with respect to the input CMY value, it is not practical to manually set the output K value one by one for all the 9261 grid points because there are too many grid points. Therefore, (C, M, Y, K) = {(0, 0, 0, 100), (0, 0, 100, 100), (0, 100, 0) are the end points of the three-dimensional color solid created by CMY. , 100), (0, 100, 100, 100), (100, 0, 0, 100), (100, 0, 100, 100), (100, 100, 0, 100), (100, 100, 100 , 100)}, an output K value is set for each of the eight vertices, and the remaining grid points are automatically determined by calculation.

  When setting the K value for each of the eight vertices, the above-described K value-image quality relationship data may be created for each of the eight vertices and referenced. In this case, a preferable K value can be set from the viewpoint of image quality improvement and density sacrifice.

  For example, the following method can be considered as an automatic determination calculation method. The output K for the coordinates (i, j, k, 100) is determined by equation (1), which is a weighted linear sum of the outputs K determined at the eight vertices.

Here, K _{(I, j, k, 100)} represents the output K value. Each weight a is calculated using the Demichel formula shown in the following equation (2).

  By using the formulas (1) and (2), it is possible to guarantee that the output K changes smoothly with respect to the input CMY, so that there is an advantage that robustness against tone jump and color shift is improved.

<K Reduction Value Determination Processing; Example 3>
In the example 2 of the K reduction value determination process, different K are set for the eight vertices. However, by applying this concept, the output CMYK for the (0, 0, 0, 100) input is set to (0, 0, 0, 100) and the single color K may be stored. When saving a single color K, for example, when characters are printed with the same input values, [1] sharpness of the characters is improved because CMY ink is not used, and [2] halftone dots are set to set K to 100%. There are advantages such as being able to minimize the influence of slipping through.

<K value reduction processing for all elements of the total amount restriction profile>
In the process so far, it was possible to determine the K reduction value for the input CMYK when K = 100% was fixed and CMY was changed in increments of 5%. However, if only the subspace of K = 100% is converted, the shape of the total amount restriction profile (the relationship between the input CMYK and the total amount restriction CMYK1) will be greatly distorted, making it impossible to perform CMS processing correctly or tones. A jump may occur. Therefore, it is necessary to perform K value reduction processing for all elements of the total amount restriction profile including subspaces other than K = 100% (step S214 in FIG. 9).

  First, input CMYK is represented by (i, j, k, n). Here, each of i, j, k, and n can take values of 0, 5, 10,..., 100% (each value in the range of 0 to 100% can be taken in increments of 5% on each axis). The output K before the K value reduction process corresponding to the input CMYK is assumed to be K (i, j, k, n). Next, assuming that the output K after the K value reduction processing is K ′ (i, j, k, n), K ′ (n = 100 in K ′ (i, j, k, n)). i, j, k, 100) have already been set by the K reduction value determination process.

  Therefore, the remaining K ′ (i, j, k, n) is determined by equation (3).

  Equation (3) compresses the entire K axis at a given CMY (ie, i, j, k) linearly with K ′ (i, j, k, 100) which is the K value of the target CMYK. Represents that. By using equation (3), the K reduction value gradually decreases smoothly as n moves away from 100%. For this reason, the K value does not change discontinuously, and the influence on tone jump and color shift can be minimized.

  In Equation (3), the K reduction value is changed linearly. However, since the purpose here is to smoothly change the K reduction value, it is not always necessary to perform linear calculation. For example, a second or higher order term may be added to Equation (3) to change the K reduction value to be smooth but non-linear.

<< CMY distribution process >>
So far, K value reduction processing has been executed for the total amount restriction profile 182 (step S210 in FIG. 9, FIG. 10). As a result, the uneven stripe characteristic is improved as much as K is reduced. Further, by reducing the K value, the ink amount used at each grid point in the total amount restriction profile 182 is reduced. Therefore, next, CMY distribution processing for increasing the CMY by the ink amount decrease is performed (step S220 in FIG. 9). This is equivalent to increasing the CMY value at each grid point, and [1] compensates for some of the density (color reproducibility) that decreases when the K value is reduced. [2] Contrast of streaks caused by KMY There is an advantage that the streak characteristics are further improved.

  The CMY distribution process is performed according to the flow shown in FIG. FIG. 11 is a flowchart of the CMY distribution process.

<CMY distribution method decision processing>
When the ink amount lost by the K value reduction process is distributed to CMY, the problem is how to distribute the ink amount. This distribution method is first determined (step S222 in FIG. 11).

<CMY distribution method decision processing; Example 1>
The simplest method of CMY distribution is a method of equally distributing CMY. This is because, for example, when the K value of a certain grid point is reduced by 6% from 100% to 94% by K value reduction processing (step S210 in FIG. 9, FIG. 10), CMY is increased by 2% each. It is a method of letting. However, this is the case where the ink amount is managed as “%”. If the ink amount is managed as a physical amount (for example, volume), the ink physical amount for 6% reduction in K is calculated in advance. As a result, the ink physical quantity CMY is increased. Advantages of this method are [1] easy implementation, [2] K value reduction processing reduces only the density without changing the hue, but maintains the hue while maintaining the hue (in this example, lightness, that is, L * For example, it works in the direction of expanding the reproduction range of (direction).

<CMY distribution method decision processing; Example 2>
The CMY distribution ratio (corresponding to “CMY increase ratio”) is not necessarily equal. Depending on the ink used for C, M, and Y, the hue may change even if it is increased by the same amount. If priority is given to the fact that the hue of each grid point does not change due to CMY distribution, the hue with respect to the increase in CMY using the color predictor 110 (forward mapping prediction function CMYK → L * a * b *) in advance is used. A CMY distribution ratio that does not change (a * b *) should be obtained and used.

<CMY distribution method decision processing; Example 3>
The CMY distribution ratio may be changed for each grid point. For example, the output CMYK before the K value reduction process is (30, 20, 0, 100), the CMYK after the K value reduction process is (30, 20, 0, 95), and the 5% reduction of K is changed to CMY. Think about distributing. At this time, a method of setting 30: 20: 0 = 3: 2: 0 as the distribution ratio can be considered. That is, the idea is that the CMY ratio of the output CMY of the total amount restriction profile 182 is changed to the CMY distribution ratio. In this case, the output CMYK after CMY distribution is (33, 22, 0, 95). By using this method, CMY is distributed in such a direction that the hue reproduction range is widened while maintaining the hue, so that there is an advantage that the color reproduction range of the printer is widened.

<CMY distribution method decision processing; Example 4>
When the target profile to be mainly used by the user is determined in advance, a method of changing the distribution ratio of CMY for each grid point is adopted, and the CMY is included in the direction in which the coverage of the color space with respect to the target profile increases as much as possible. May be distributed. An embodiment in the case of adopting this method will be described below.

  First, it is assumed that the output K value has already been determined by the K value reduction process for the input of (C, M, Y, K) = (i, j, k, n). Also, the output CMY values before CMY distribution are already known. If the color predictor 110 is used, it is possible to predict a * b * (representing the hue) for the output CMYK value before CMY distribution. On the other hand, since a * b * for the (C, M, Y, K) = (i, j, k, 100) input of the target profile 188 is known, a * b * before CMY distribution is the target profile 188. CMY distribution can be performed in a direction approaching a * b *.

<CMY distribution processing for all elements of the total amount restriction profile>
The CMY distribution method determination process (step S222 in FIG. 11) determines the CMY distribution ratio for each grid point of the total amount restriction profile after the K value reduction process. Thereafter, according to each distribution ratio, before the K value reduction process. CMY distribution is performed for each grid point until the ink amount returns to (step S224 in FIG. 11). Thereby, the SD unit optimization total amount restriction profile 184 (see FIG. 8) is completed.

  Since the total amount restriction profile 182 and the SD portion optimization total amount restriction profile 184 store the ink amount at each grid point, troubles due to excessive ink amount do not occur when the SD portion optimization total amount restriction profile 184 is used. That is, the total color material amount is defined by the total color material amount limit value.

  The CMY distribution processing described with reference to FIG. 11 is performed by the CMY distribution processing unit 144 of FIG.

<Configuration of CMY Distribution Processing Unit 144>
FIG. 12 is a block diagram showing the configuration of the CMY distribution processing unit 144. The CMY distribution processing unit 144 includes a CMY distribution method determination processing unit 202, a CMY distribution ratio storage unit 204, and a CMY increase processing unit 206. The CMY distribution method determination processing unit 202 performs processing for determining a CMY distribution method according to a predetermined program. For example, any one of the above-described “CMY distribution method determination processing” examples 1 to 4 may be programmed in advance, or a user may select an operation from among a plurality of methods. The configuration may be such that one method is selected in accordance with or by automatic selection based on a program.

  Data defining the CMY distribution rate specified according to the method determined by the CMY distribution method determination processing unit 202 (referred to as “CMY distribution ratio data”, which corresponds to “CMY increase ratio data”) is stored in the CMY distribution ratio storage unit 204. Is done.

<< SD section optimization total amount restriction profile >>
The SD part optimization total amount restriction profile 184 (see FIG. 8) is a profile created by the SD part optimization process, and the input CMYK and the total quantity restriction CMYK after the SD part optimization process (hereinafter referred to as “total quantity restriction CMYK2”). (Corresponding to “second total amount limit CMYK value”) as a LUT. The SD unit optimization total amount restriction profile 184 is defined using, for example, an ICC profile format. The SD unit optimization total amount restriction profile 184 is stored in the SD unit optimization total amount restriction profile storage unit denoted by reference numeral 146 in FIG.

<< SD section optimized printer profile creation process >>
The SD unit optimization printer profile creation processing unit 150 (see FIGS. 3 and 8) has the same processing contents as the printer profile creation processing unit 130, but one input is different. That is, the SD unit optimized printer profile creation processing unit 150 receives the color predictor 110 and the SD unit optimized total amount restriction profile 184 as input, and creates an SD unit optimized printer profile 190 (see FIG. 8). The SD part optimized printer profile 190 is printed by the CMYK value before the color material total amount restriction and the CMYK after the color material total quantity restriction by the SD part optimization total amount restriction profile (total amount restriction CMYK2 in FIG. 8). This profile holds the relationship between colors (L * a * b *) as an LUT.

  L * a * b * for the total amount limit CMYK1 can be predicted using the forward mapping prediction function of the color predictor 110. If it is determined that the accuracy of the color predictor 110 is not sufficient, a color chart may be created once again using only the CMYK values defined by the total amount limit CMYK1, and color measurement may be performed after printing. In FIG. 3, the arrows from the color predictor 110 to the printer profile creation processing unit 130 and the SD unit optimization printer profile creation processing unit 150 are broken lines, and it is not necessary to use the color predictor 110. Is shown.

<< Processing flow >>
FIG. 13 is a flowchart of processing for creating an SD unit optimized total amount restriction profile and an SD unit optimized printer profile in the image processing apparatus according to the present embodiment.

  As illustrated, the image processing apparatus 14 first acquires learning data of the color predictor 110 (“learning data acquisition process of color predictor” in step S302). The specific contents of this step are as described in FIG.

  CMYK-L * a * b * relation data (mapping data) 194 used in forward mapping prediction and reverse mapping prediction of the color predictor 110 is generated from the learning data obtained in the step S302 of FIG.

  After step S302 (color predictor learning data acquisition step) or before this, K value-image quality relationship data is acquired (step S304, "K value-image quality relationship data acquisition step"). The specific contents of the K value-image quality relationship data acquisition step are as described with reference to FIGS. The K value-image quality relationship data 186 generated in step S304 of FIG. 12 is stored in the K value-image quality relationship data storage unit 134 (see FIG. 3).

  Color material total amount restriction profile creation processing is performed after or before step S304 (K value-image quality relationship data acquisition step) in FIG. 12 (step S306). The specific contents of the total color material amount restriction profile creation process (step S306) are as described in FIG. The total amount restriction profile 182 generated in the process of step S306 in FIG. 12 is stored in the total amount restriction profile storage unit 122 (see FIG. 3).

  The processing order of steps S302, S304, and S306 can be changed as appropriate. These processes are not necessarily performed continuously, and each process can be performed at independent timing.

  Next, printer profile creation processing is performed (step S308), and a printer profile 196 is generated. In this embodiment, it is not necessary to directly use the printer profile 196 for the color conversion process. However, as described above, the printer profile 196 is created in advance, and this profile is used as necessary. It is possible to perform printing to which color conversion is applied when the SD unit optimization processing is not performed. The printer profile creation processing step (step S308) is performed by the printer profile creation processing unit 130 described with reference to FIG.

  Next, target profile information is acquired (step S310). Data of one type or a plurality of types of target profiles may be stored in the image processing apparatus 14 in advance, or the configuration may be such that data is taken in from the outside as necessary. The target profile information used in the submitted data 50 is referred to.

  Next, an SD unit optimization process is performed (step S312), and an SD unit optimization total amount restriction profile 184 is generated. The specific contents of the SD unit optimization process (step S312) are as described with reference to FIGS. Based on the generated SD unit optimized total amount restriction profile 184, an SD unit optimized printer profile creation process is performed (step S314 in FIG. 12), and an SD unit optimized printer profile 190 is generated.

<< CMS processing >>
So far, the method of creating the SD unit optimized total amount restriction profile 184 and the SD unit optimized printer profile 190 has been described. Next, how CMS processing is performed using these profiles will be described.

  FIG. 14 is a flowchart showing an outline of CMS processing in the present embodiment. First, there is submission data 50 for printing, and the submission data 50 is taken into the image processing apparatus 14 (“image data input process” in step S402). It is assumed that the input data 50 is created according to some target profile. The submitted data 50 may be CMYK data or RGB data, but it is created according to the target profile, which means that the color (L * a * b *, etc.) in the device-independent color space is known. The submitted data 50 can be considered as an L * a * b * image, for example.

  On the other hand, since the relationship between CMYK and L * a * b * on the printing device can be understood by using the SD section optimized printer profile 190, the CMYK (or the submission data 50) is stored with L * a * b * stored. RGB) can be converted into CMYK of the printing device (corresponding to “CMS processing step” and “color conversion processing step” in step S404). The CMYK of the printing device converted in the CMS processing step shown in step S404 corresponds to the CMYK data (reference numeral 70 in FIG. 13) before the total color material amount limit. In S406), the SD portion optimized total amount restriction profile 184 is used to convert the CMYK before the total amount restriction into the CMYK2 after the total amount restriction. Thus, the CMYK data (reference numeral 70) after the total amount limitation generated through the color material total amount limitation process (step S406) is output as the data after the color conversion process (step S408, “data output process”). The CMYK data 70 after this total amount restriction is input to the printing device, and printing is performed. In this way, printing in which the color of the submitted data 50 is saved becomes possible.

  The CMS processing step (step S404) is performed by the processing of the CMS processing unit 162 in FIG. 3, and the total color material amount restriction processing step (step S406 in FIG. 13) is performed by the total color material amount restriction processing unit 164 in FIG. It is done by processing. Further, the post-color conversion data output step (step S408 in FIG. 13) is performed through the data output unit 166 in FIG.

<About color reproduction range>
FIG. 15 is a schematic diagram of the color gamut of the SD unit optimized printer profile created in this embodiment. Here, the L * a * b * coordinate system is used as the color system. Although it is actually represented by a three-dimensional color solid, it is shown as a two-dimensional color gamut for the sake of simplicity and illustration. In FIG. 15, the color gamut surrounded by the solid line 210 is the color gamut of the printer profile 196. A color gamut surrounded by a solid bold line 220 indicates a color gamut of the SD unit optimized printer profile 190. A color gamut surrounded by a broken line 230 indicates the color gamut of the target profile.

  The color reproduction area 220 of the SD unit optimized printer profile 190 created in the present embodiment is a high brightness area as compared to the color reproduction area 210 of the printer profile 196 that is the potential color reproduction capability of the printing press 18. The color reproduction capability of the printing press 18 is utilized to the maximum, and the color solid is compressed toward the low brightness area (shadow portion), and approaches the color gamut (target area) 230 of the target profile.

  That is, the SD unit optimized total amount restriction profile 184 and the SD optimized printer profile 190 in this embodiment optimize the SD unit assuming a certain target profile. The area other than the SD portion (medium-high brightness area) approaches the original total amount restriction profile and the shape of the printer profile as the brightness increases. In other words, in the medium-high lightness region, the profile has drawn out the color reproduction capability of the printing device almost fully. Therefore, if a profile defined up to a certain level of density is used as the target profile for SD section optimization, sufficient accuracy can be obtained without recreating the SD section optimization profile group based on the target profile of the submitted data as described above. Color matching can be performed with.

  As shown in FIG. 15, when the color reproduction area 220 of the SD unit optimized printer profile 190 includes the target area 230, the color of the target area 230 can be completely reproduced. However, when emphasis is placed on image quality improvement (smoothness improvement) rather than color reproducibility, there may be a mode in which the K value is further reduced at the expense of the color reproduction range, and therefore the SD section optimized printer profile 190. It is not necessarily required that the color reproduction area 220 of the second area includes the target area 230. From the viewpoint of reproducing the color of the target area 230 as much as possible, the shape may be as close as possible to the target area 230.

  According to such a configuration, not only can the target color be stored, but also printing that optimizes the image quality and the amount of color material used in the SD section is possible.

<Effect of SD section optimization processing>
The SD section optimized printer profile 190 created in the present embodiment creates a conversion relationship so as to make the best use of the color gamut potentially possessed by the printing device in the high lightness region, and the low lightness region (SD The conversion relationship is created so as to approach the color gamut of the target profile as it approaches (part).

  Therefore, compared with the case where the color reproduction range of the low brightness area (SD part) is created so as to make the best use of the potential of the printing device, the K-CMY distribution ratio targeted for a specific target profile is used. Print more accurately. This is because it becomes difficult to depend on the CMS processing method.

  In addition, since the color reproduction range of the high brightness area is created by making the best use of the potential capabilities of the printing device, highly saturated color information such as spot color data was mixed in the submitted data. Even in this case, optimal color reproduction can be performed within the range of the color reproduction capability that the printing device potentially has.

  On the other hand, the method of the present embodiment can flexibly adjust the K-CMY distribution rate in terms of image quality or color material usage (cost) in the low brightness area (SD section).

  Therefore, the graininess and unevenness characteristics of the SD portion can be flexibly improved by relatively reducing the amount of K used in the low brightness area (SD portion) compared to CMY.

  Also, by increasing the amount of K used in the low brightness area (SD part) relatively compared to CMY, the sharpness of black characters and line drawings in the SD part and the color material usage cost can be flexibly improved.

<Advantages of this embodiment>
(1) The K value can be reduced to a level where the uneven stripe characteristic is acceptable. By reducing the K value, the uneven stripe characteristic is improved.

  (2) CMY is increased within the range of the ink amount reduced by the K value reduction. By replacing the amount of ink reduced by the reduction of the K value with CMY, not only the unevenness characteristic can be further improved, but also the density (color reproduction range) reduced by the reduction of the K value is restored as much as possible.

  (3) The K value reduction degree (K value reduction amount) can be changed for each grid point of the total amount restriction profile. By adopting such a configuration, for example, for an input such as (C, M, Y, K) = (100, 100, 100, 100) where it is desired to ensure that a high density can be output, K is not much. It is possible to improve the stripe unevenness characteristic by reducing K much for inputs such as (10, 10, 10, 100) that do not need to be reduced and do not require a very high density.

  (4) Also, for example, by designing the output CMYK to be stored in (0, 0, 0, 100) for (0, 0, 0, 100) input, sharpness or white spots of monochrome black characters, etc. The problem can be avoided.

  (5) Along with the K value reduction, when increasing CMY, the increase ratio (CMY distribution ratio) of each color of CMY can be changed. According to this embodiment, since the ink amount at each grid point is stored in the total amount restriction profile and the SD portion optimization total amount restriction profile, the ink amount becomes excessive by using the SD portion optimization total amount restriction profile. Printing trouble can be prevented.

<Modification 1>
In the above-described embodiment, the effect of reducing streaks by a single-pass ink jet printer has been described. However, the present invention can be similarly applied to printing apparatuses using other printing methods.

  In the embodiment of the present invention described above, the configuration requirements can be appropriately changed, added, and deleted without departing from the spirit of the present invention. The present invention is not limited to the embodiments described above, and many modifications are possible by those having ordinary knowledge in the field within the technical idea of the present invention.

<Various aspects of the disclosed invention>
As will be understood from the description of the embodiment described in detail above, the present specification and drawings include disclosure of various technical ideas including the invention described below.

  (First aspect): Create a profile to be used for color conversion processing that adjusts the color expression of a printing apparatus that performs printing using cyan (C), magenta (M), yellow (Y), and black (K) color materials. A profile creation device that limits the total amount of color material used when forming a printed matter by a printing device within a predetermined limit value and is as wide as possible within the range of color reproduction capability of the printing device. A first total amount restriction profile storing means for storing a first total amount restriction profile in which a conversion relationship between an input CMYK value and a first output CMYK value so as to be a color gamut is stored; and a first total amount restriction profile C value reduction processing means for reducing the output K value to determine the post-reduction K value, and CMY increase for determining the CMY increase rate when the CMY value is increased with the K value reduction by the K value reduction processing means Based on the ratio determining means and the CMY increase ratio data defining the CMY increase ratio, the CMY increase is performed to increase the CMY value within the range of the color material amount reduced by the K value reduction process of the K value reduction processing means. The input CMYK value and the second CMYK value associated with the processing unit and the input CMYK value are associated with the second output CMYK value expressed by the CMYK value after the reduction and the CMY value after the CMY increase process by the CMY increase processing unit. A profile creation apparatus comprising: a second total amount restriction profile creation processing unit that creates a second total amount restriction profile that defines a conversion relationship with an output CMYK value.

  According to this aspect, it is possible to create a profile (second total amount restriction profile) in which the unevenness characteristic is improved within the range of restriction on the total amount of color material defined by the restriction value. The second total amount restriction profile can be created as a four-dimensional conversion lookup table of input CMYK and output CMYK.

  (Second Aspect): The profile creating apparatus according to the first aspect, comprising K value-image quality relationship data storage means for storing K value-image quality relationship data defining a relationship between the K value reduction amount and the image quality, The K value reduction processing means may be configured to determine the K value reduction amount based on the K value-image quality relationship data.

  For example, a bar chart created by changing the input K value is output by a printing apparatus, and the relationship between K value and image quality is obtained by evaluating the image quality (for example, the visibility of streaks) for each K value. it can. The K value reduction amount can be determined based on such K value-image quality relationship data.

  (Third Aspect): In the profile creation device according to the second aspect, the K value-image quality relationship data defines the relationship between the K value and the image quality evaluation value obtained by evaluating the visibility of the unevenness of the shadow portion. be able to.

  According to this aspect, it is possible to grasp an appropriate K value reduction amount that has a high effect of improving the unevenness of the shadow portion.

  (Fourth aspect): In the profile creation apparatus according to any one of the first to third aspects, a device-independent color space value of a color output by the printing apparatus is predicted from CMYK values input to the printing apparatus. The color predicting means includes a forward mapping predicting means for performing the above-described processing and a reverse mapping predicting means for obtaining the CMYK value from the device-independent color space value.

  The data defining each mapping of the forward mapping predicting means and the reverse mapping predicting means constituting the color predicting means is, for example, outputting a color chart including a plurality of color patch groups by a printing device, and measuring each patch by colorimetry. It can be generated from a learning data group in which CMYK values and colorimetric values (device-independent color space values) for each patch are associated with each other.

  (Fifth Aspect): In the profile creation device according to any one of the first aspect to the fourth aspect, the CMY increase ratio determining means maintains the hue of each lattice point of the profile and widens the density reproduction range. The CMY can be increased.

  In defining an increase ratio for increasing CMY after reducing K at each grid point of the profile, a configuration for determining a CMY increase rate for increasing CMY in a direction to preserve the hue of each grid point and widen the reproduction range of density can do.

  (Sixth Aspect): In the profile creation device according to any one of the first aspect to the fifth aspect, the CMY increase ratio determining means expands a reproduction range of saturation while maintaining a hue of each lattice point of the profile. It can be configured to increase CMY in the direction.

  In defining an increase ratio for increasing CMY after reducing K at each grid point of the profile, a configuration for determining a CMY increase rate for increasing CMY in a direction to preserve the hue of each grid point and widen the reproduction range of saturation It can be.

  (Seventh aspect): Target profile information acquisition means for acquiring target profile information in a color space in which the target color of the submitted data is defined in the profile creation device according to any one of the first to sixth aspects , And the CMY increase ratio determining means may determine the CMY increase ratio in a direction in which the coverage rate of the color space with respect to the target profile is increased.

  According to this aspect, the color gamut of the target color space can be covered as much as possible.

  (Eighth aspect): In the profile creation device according to any one of the first to seventh aspects, the second output CMYK value defined in the second total amount restriction profile and the device-independent color space A shadow part optimizing printer profile creation processing unit for creating a shadow part optimizing printer profile that defines the correspondence with values can be provided.

  According to this aspect, it is possible to obtain a printer profile in which the shadow portion is optimized from the viewpoint of improving the uneven stripe characteristics and securing the color reproduction range.

  (Ninth aspect): Creates a profile used for color conversion processing for adjusting the color expression of a printing apparatus that performs printing using cyan (C), magenta (M), yellow (Y), and black (K) color materials. A profile creation method for limiting the total amount of color materials used when forming a printed matter by a printing device within a predetermined limit value and as wide as possible within the range of color reproduction capability of the printing device. A first total amount restriction profile storage step of storing in a storage means a first total amount restriction profile in which a conversion relationship between an input CMYK value and a first output CMYK value so as to be a color gamut is defined; The K value reduction processing step that determines the K value after reduction by reducing the output K value of the total amount restriction profile, and the CMY increase rate when the CMY value is increased in accordance with the K value reduction by the K value reduction processing step is determined Do Based on the CMY increase ratio determining step and the CMY increase ratio data defining the CMY increase rate, the CMY value is increased within the range of the color material amount reduced by the K value reduction process of the K value reduction process step. The input CMYK value is associated with the second output CMYK value represented by the CMY increase process step and the input CMYK value and the second output CMYK value represented by the CMYK value of the CMY value after the CMY increase process by the CMY increase process step. And a second total amount restriction profile creation processing step of generating a second total amount restriction profile defining a conversion relationship with the second output CMYK value.

  Regarding the profile creation method of the ninth aspect, it is possible to appropriately combine the same features as the aspects of the second aspect to the eighth aspect. In this case, the matter specified as “means” can be grasped as “process” corresponding to the means.

  (Tenth aspect): In the profile creation method according to the ninth aspect, a shadow that defines a correspondence relationship between the second output CMYK value defined in the second total amount restriction profile and the value of the device-independent color space A shadow portion optimized printer profile creation processing step for creating a portion optimized printer profile can be adopted.

  (Eleventh aspect): The profile creation apparatus according to the eighth aspect, the image input means for taking in the input data, and the shadow part optimization printer profile is applied to the input data to obtain CMYK data for the printing apparatus. A color adjustment processing means for conversion; a color material total amount restriction processing means for converting the CMYK data generated by the color adjustment processing means into CMYK data after applying the second total amount restriction profile to the color material total amount restriction; A color conversion device comprising:

  According to this aspect, it is possible to generate CMYK data suitable for print output of the printing apparatus from the submitted data.

  (Twelfth aspect): Each step of the profile creation method according to the tenth aspect, an image input process for fetching input data, and a shadow part optimization printer profile for the input data, and for a printing apparatus Color adjustment processing step for converting to CMYK data, and color material total amount restriction processing for converting CMYK data generated by the color adjustment processing step into CMYK data after applying the second total amount restriction profile to color material total amount restriction A color conversion method including a process.

  (Thirteenth aspect): A profile used for color conversion processing for adjusting the color expression of a printing apparatus that performs printing using cyan (C), magenta (M), yellow (Y), and black (K) color materials is created. A program for creating a profile that limits the total amount of color material used when forming a printed matter by a printing device to a predetermined limit value, and the color reproduction that the printing device potentially has First total amount restriction profile storage means for storing a first total amount restriction profile in which the conversion relationship between the input CMYK value and the first output CMYK value is defined so that the color gamut is as wide as possible within the range of capability. And a K value reduction processing unit that determines the K value after reduction by reducing the output K value of the first total amount restriction profile, and a CMY value when the K value is reduced by the K value reduction processing unit. CMY increase ratio determining means for determining the increase ratio of CMY, and CMY within the range of the color material amount reduced by the K value reduction processing of the K value reduction processing means based on the CMY increase ratio data defining the increase ratio of CMY. CMY increase processing means for increasing the value, and a second output CMYK represented by a CMYK value composed of the K value after reduction and the CMY value after CMY increase processing by the CMY increase processing means with respect to the input CMYK value A program for functioning as second total amount restriction profile creation processing means for generating a second total amount restriction profile that associates values and defines a conversion relationship between an input CMYK value and a second output CMYK value.

  Regarding the program of the thirteenth aspect, the same features as those of the second to eighth aspects can be appropriately combined.

  (14th aspect): The program described in the 13th aspect defines the correspondence relationship between the second output CMYK value defined in the second total amount restriction profile and the value of the device-independent color space. The shadow portion optimized printer profile creation processing means for creating the shadow portion optimized printer profile can be configured.

  (15th aspect): A color conversion program for adjusting the color expression of a printing apparatus that performs printing using color materials of cyan (C), magenta (M), yellow (Y), and black (K). A program for causing a computer to function as each unit of the color conversion device according to the eleventh aspect.

  (Sixteenth aspect): CMYK data for printing the submitted data using the profile creation apparatus according to the eighth aspect, the shadow part optimized printer profile created by the profile creation apparatus, and the second total amount restriction profile A color conversion processing means for converting to a printing system, and a printing apparatus that performs printing based on color-converted image data generated by the color conversion processing means.

  DESCRIPTION OF SYMBOLS 10 ... Printing system, 14 ... Image processing apparatus, 16 ... Colorimeter, 18 ... Printing machine, 20 ... Controller, 43 ... Hard disk device, 45 ... Communication interface part, 47 ... Interface part for peripheral devices, 50 ... Submission data , 110 ... color predictor, 114 ... forward mapping prediction section, 116 ... reverse mapping prediction section, 120 ... total color material amount restriction profile creation processing section, 122 ... total quantity restriction profile storage section, 134 ... K value-image quality relation data storage section 136 ... Target profile storage unit, 140 ... SD unit optimization processing unit, 142 ... K value reduction processing unit, 144 ... CMY distribution processing unit, 146 ... SD unit optimization total amount restriction profile storage unit, 150 ... SD unit optimization Printer profile creation processing unit, 160... Image input interface unit, 162... CMS processing unit, 164. Limit processing unit, 182... Total amount limitation profile, 184. SD unit optimization total amount limitation profile, 186... K value-image quality related data, 188... Target profile, 190. 204, CMY distribution ratio storage unit, 206 ... CMY increase processing unit

Claims (16)

A profile creation device that creates a profile used for color conversion processing that adjusts the color expression of a printing device that performs printing using cyan (C), magenta (M), yellow (Y), and black (K) color materials. And
Limiting the total amount of color material used when forming a printed matter by the printing device to a predetermined limit value and making the color gamut as wide as possible within the range of the color reproduction capability of the printing device. First total amount restriction profile storage means for storing a first total amount restriction profile in which a conversion relationship between an input CMYK value and a first output CMYK value is defined;
K value reduction processing means for reducing the output K value of the first total amount restriction profile to determine the post-reduction K value;
CMY increase ratio determining means for determining an increase ratio of CMY when the CMY value is increased in accordance with the K value reduction by the K value reduction processing means;
CMY increase processing means for performing processing for increasing CMY values within the range of the color material amount reduced by the K value reduction processing of the K value reduction processing means based on CMY increase ratio data defining the CMY increase ratio; ,
The input CMYK value and the second output CMYK value represented by the CMYK value of the CMY value after the CMY increase processing by the CMY increase processing unit are associated with the input CMYK value and the second CMYK value is correlated with the second CMYK value. Second total amount restriction profile creation processing means for generating a second total amount restriction profile that defines a conversion relationship with the output CMYK values of
A profile creation device comprising: K value-image quality relationship data storage means for storing K value-image quality relationship data defining the relationship between the K value reduction amount and image quality;
The profile creation apparatus according to claim 1, wherein the K value reduction processing unit determines a K value reduction amount based on the K value-image quality relationship data.   3. The profile creation device according to claim 2, wherein the K value-image quality relationship data defines a relationship between an image quality evaluation value obtained by evaluating the visibility of the unevenness of a shadow portion and a K value.   Forward mapping prediction means for predicting device-independent color space values of colors output from the printing apparatus from CMYK values input to the printing apparatus; and inverse mapping prediction means for obtaining CMYK values from device-independent color space values; The profile creation apparatus according to any one of claims 1 to 3, further comprising color prediction means including   5. The profile creation apparatus according to claim 1, wherein the CMY increase ratio determination unit increases CMY in a direction in which a hue reproduction range is expanded while maintaining a hue of each lattice point of the profile.   6. The profile creation device according to claim 1, wherein the CMY increase ratio determination unit increases CMY in a direction in which a hue reproduction range is widened while maintaining a hue of each lattice point of the profile. A target profile information acquisition means for acquiring target profile information of a color space that defines the target color of the input data;
7. The profile creation device according to claim 1, wherein the CMY increase ratio determining unit determines a CMY increase ratio in a direction in which a color space coverage ratio with respect to the target profile is increased.   Shadow part optimized printer profile creation for creating a shadow part optimized printer profile that defines the correspondence between the second output CMYK value defined in the second total amount restriction profile and the value of the device-independent color space The profile creation apparatus according to claim 1, further comprising a processing unit. This is a profile creation method for creating a profile used for color conversion processing for adjusting the color expression of a printing apparatus that performs printing using cyan (C), magenta (M), yellow (Y), and black (K) color materials. And
Limiting the total amount of color material used when forming a printed matter by the printing device to a predetermined limit value and making the color gamut as wide as possible within the range of the color reproduction capability of the printing device. A first total amount restriction profile storage step of storing in a storage means a first total amount restriction profile in which a conversion relationship between an input CMYK value and a first output CMYK value is defined;
A K value reduction processing step of reducing the output K value of the first total amount restriction profile and determining a post-reduction K value;
A CMY increase ratio determining step for determining an increase ratio of CMY when the CMY value is increased in accordance with the K value reduction by the K value reduction processing step;
A CMY increase processing step for performing a process for increasing the CMY value within the range of the color material amount reduced by the K value reduction processing in the K value reduction processing step based on the CMY increase ratio data defining the CMY increase rate; ,
The input CMYK value is correlated with the second output CMYK value represented by the CMYK value of the CMY value after the CMY increasing process in the CMY increasing process step and the input CMYK value and the second CMYK value. A second total amount restriction profile creation processing step for generating a second total amount restriction profile that defines a conversion relationship with the output CMYK value of
Profile creation method including   Shadow part optimized printer profile creation for creating a shadow part optimized printer profile that defines the correspondence between the second output CMYK value defined in the second total amount restriction profile and the value of the device-independent color space The profile creation method according to claim 9 including a processing step. The profile creation device according to claim 8,
An image input means for capturing the input data;
Color adjustment processing means for applying the shadow part optimized printer profile to the submitted data and converting it into CMYK data for a printing apparatus;
Color material total amount restriction processing means for applying the second total amount restriction profile to the CMYK data generated by the color adjustment processing means and converting it into CMYK data after color material total quantity restriction;
A color conversion device comprising: Each step of the profile creation method according to claim 10,
An image input process to capture the submitted data,
A color adjustment process for converting the submission data into CMYK data for a printing apparatus by applying the shadow part optimized printer profile;
A color material total amount restriction processing step for converting the CMYK data generated by the color adjustment processing step into CMYK data after the color material total amount restriction by applying the second total amount restriction profile;
Including color conversion method. Program for creating a profile for creating a profile used for color conversion processing for adjusting the color expression of a printing apparatus that performs printing using color materials of cyan (C), magenta (M), yellow (Y), and black (K) Because
Computer
The total amount of color material used when forming a printed matter by the printing apparatus is limited to a predetermined limit value, and the color gamut is as wide as possible within the range of the potential color reproduction capability of the printing apparatus. First total amount restriction profile storage means for storing a first total amount restriction profile in which the conversion relationship between the input CMYK value and the first output CMYK value is defined as described above,
K value reduction processing means for reducing the output K value of the first total amount restriction profile to determine the post-reduction K value;
CMY increase ratio determining means for determining an increase ratio of CMY when the CMY value is increased in accordance with the K value reduction by the K value reduction processing means;
CMY increase processing means for performing processing for increasing CMY values within the range of the color material amount reduced by the K value reduction processing of the K value reduction processing means based on CMY increase ratio data defining the CMY increase ratio; ,
The input CMYK value and the second output CMYK value represented by the CMYK value of the CMY value after the CMY increase processing by the CMY increase processing unit are associated with the input CMYK value and the second CMYK value is correlated with the second CMYK value. Second total amount restriction profile creation processing means for generating a second total amount restriction profile that defines a conversion relationship with the output CMYK value of
Program to function as. Computer
Shadow part optimized printer profile creation for creating a shadow part optimized printer profile that defines the correspondence between the second output CMYK value defined in the second total amount restriction profile and the value of the device-independent color space The program according to claim 13 for causing a function as processing means. A color conversion program for adjusting the color expression of a printing apparatus that performs printing using color materials of cyan (C), magenta (M), yellow (Y), and black (K),
Computer
The program for functioning as each means of the color conversion apparatus of Claim 11. The profile creation device according to claim 8,
Color conversion processing means for converting the submitted data into CMYK data for printing using the shadow portion optimized printer profile created by the profile creation device and the second total amount restriction profile;
A printing apparatus that performs printing based on the color-converted image data generated by the color conversion processing unit;
Printing system equipped with.

Images