Information processing apparatus, image forming apparatus, image forming system, and program

Abstract

To expand a color gamut reproduced by an image forming apparatus compared with a case where only one area of a secondary color is expanded by one color material.SOLUTION: When a first color material, a second color material, a third color material, and a fourth color material different in a color space from the first color material by less than a threshold, can be used, a processor of an information processing apparatus outputs the combination of values of color materials reproducing a first color that expands the color gamut of a secondary color obtained by mixing the first color material and the second color material, and a second color that expands the color gamut of a secondary color obtained by mixing the first color material and the third color material.SELECTED DRAWING: Figure 24

Description

[Technical Field]

[0001] The present invention relates to an information processing apparatus, an image forming apparatus, an image forming system, and a program. [Background technology]

[0002] In color printing, the four basic colors are C (cyan), M (magenta), Y (yellow), and K (black). Today, to expand the color gamut, colors other than these four (hereinafter also called "spot colors") are sometimes used. Examples of spot colors include O (orange), G (green), R (red), V (violet), and B (blue). Recently, P (fluorescent pink) and other fluorescent colors are also used as spot colors. Mixing fluorescent colors into pigments makes it possible to reproduce more vivid colors than with basic colors. In other words, the color gamut is expanded. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2011-10083 [Overview of the project] [Problems that the invention aims to solve]

[0004] The color space, which includes the color gamut that can be represented by the three colors C, M, and Y, is divided into three regions corresponding to secondary colors. Secondary colors are colors that are represented by mixing two colors: C, M, and Y. For example, the region corresponding to the secondary color of Y and M is called the O region, the region corresponding to the secondary color of C and M is called the V region, and the region corresponding to the secondary color of C and Y is called the G region.

[0005] As mentioned above, P belongs to the O region in the color space. Therefore, in the case of Patent Document 1, P is used to extend the O region. Incidentally, P is a color close to M, which is located at the boundary between the O and V regions. Therefore, P can also be used to extend the V region. However, to date, P has only been used to extend either the O or V region, or both at the same time. In other words, a technique to simultaneously extend both the O and V regions using P has not yet been established.

[0006] The present invention aims to broaden the color gamut reproduced by an image forming apparatus compared to the case where only one of the secondary color regions is extended with a single colorant. [Means for solving the problem]

[0007] The invention described in claim 1 has a processor, the processor has a first colorant, a second colorant, a third colorant, and the color space of the first colorant Difference in distance or phase The difference Regarding the difference This is an information processing device that outputs a combination of colorant values ​​that reproduce a first color that expands the color gamut of the secondary colors of the first and second colorants, and a second color that expands the color gamut of the secondary colors of the first and third colorants, when it is possible to use a fourth colorant below a threshold. The invention described in claim 2 is an information processing apparatus according to claim 1, wherein the processor outputs a combination of values ​​for the first colorant, the second colorant, and the fourth colorant for the first color, and outputs a combination of values ​​for the first colorant, the third colorant, and the fourth colorant for the second color. The invention described in claim 3 is the information processing device according to claim 2, wherein the first color gamut and the second color gamut are defined as connected color gamuts that do not overlap with each other. The invention described in claim 4 is an information processing apparatus according to claim 1, wherein the processor determines a combination of the value of the first colorant, the value of the second colorant, and the value of the third colorant after determining the value of the fourth colorant that reproduces the first color or the second color. The invention described in claim 5 is an information processing apparatus according to claim 4, wherein, when the processor outputs a combination of colorants that reproduce the first color, it first determines the value of a first intermediate color between the color of the first colorant and the color of the second colorant, then considers the color of the first intermediate color as a fixed value and determines a combination of the value of the first colorant and the value of the second colorant, and finally determines the value of the first intermediate color to be the value of the fourth colorant. The invention described in claim 6 is an information processing apparatus according to claim 4, wherein, when the processor outputs a combination of colorants that reproduce the second color, it first determines the value of a second intermediate color between the color of the first colorant and the color of the third colorant, then considers the value of the second intermediate color as a fixed value and determines a combination of the value of the first colorant and the value of the third colorant, and finally determines the value of the second intermediate color as the value of the fourth colorant. The invention described in claim 7 is an information processing apparatus according to claim 1, wherein the first colorant, the second colorant, and the third colorant correspond to basic colors excluding black, and the fourth colorant corresponds to a fluorescent color. The invention described in claim 8 comprises a forming unit that forms an image on a medium using a plurality of colorants, and a processor, wherein the processor uses a first colorant, a second colorant, a third colorant, and the first colorant in the color space Difference in distance or phase The difference Regarding the difference This is an image forming apparatus that, when a fourth colorant below a threshold value can be used in the forming section, outputs a combination of colorant values ​​that reproduces a first color that expands the color gamut of the secondary color of the first and second colorants, and a second color that expands the color gamut of the secondary color of the first and third colorants. The invention described in claim 9 is an image forming system comprising an image forming apparatus that forms an image on a medium using at least a first colorant, a second colorant, a third colorant, and a fourth colorant, and an information processing apparatus according to any one of claims 1 to 6. The invention described in claim 10 relates to a first colorant, a second colorant, a third colorant, and the color space of the first colorant. Difference in distance or phase The difference Regarding the differenceThis program provides a function to enable the computer to output a combination of colorant values ​​that reproduce a first color that expands the color gamut of the secondary colors of the first and second colorants, and a second color that expands the color gamut of the secondary colors of the first and third colorants, when it is possible to use a fourth colorant below a threshold. The invention described in claim 11 has a processor, the processor has a first colorant, a second colorant, a third colorant, and the color space of the first colorant Difference in distance or phase The difference Regarding the difference This is an information processing device that generates a first color chart in which colors reproduced by a combination of the colors of the first color material, the second color material, and the third color material are arranged, when the use of a fourth color material below a threshold is possible; a second color chart in which colors reproduced by a combination of the colors of the first color material, the second color material, and the fourth color material are arranged; and a third color chart in which colors reproduced by a combination of the colors of the first color material, the third color material, and the fourth color material are arranged. The invention described in claim 12 relates to a first colorant, a second colorant, a third colorant, and the color space of the first colorant. Difference in distance or phase The difference Regarding the difference This program enables the computer to perform the following functions when it is possible to use a fourth colorant below a threshold: generate a first color chart which contains the colors reproduced by combinations of the first colorant, the second colorant, and the third colorant; generate a second color chart which contains the colors reproduced by combinations of the first colorant, the second colorant, and the fourth colorant; and generate a third color chart which contains the colors reproduced by combinations of the first colorant, the third colorant, and the fourth colorant. [Effects of the Invention]

[0008] According to the invention described in claim 1, the color gamut that can be reproduced by the image forming apparatus can be widened compared to the case where only one of the secondary color regions is extended with a single colorant. According to the invention described in claim 2, the first color and the second color can be output by a combination including the fourth colorant. According to the invention described in claim 3, it is possible to clarify the color gamuts shared by the first color and the second color when determining the combination including the fourth colorant. According to the invention described in claim 4, it is possible to efficiently determine the combination of values using the fourth colorant. According to the invention described in claim 5, it is possible to efficiently determine the combination of values using the fourth colorant for the first color. According to the invention described in claim 6, it is possible to efficiently determine the combination of values using the fourth colorant. According to the invention described in claim 7, it is possible to expand the color gamut that can be reproduced with vivid colors. According to the invention described in claim 8, it is possible to widen the color gamut reproduced by the image forming apparatus as compared with the case where only one of the secondary color regions is expanded with one colorant. According to the invention described in claim 9, it is possible to widen the color gamut reproduced by the image forming apparatus as compared with the case where only one of the secondary color regions is expanded with one colorant. According to the invention described in claim 10, it is possible to widen the color gamut reproduced by the image forming apparatus as compared with the case where only one of the secondary color regions is expanded with one colorant. According to the invention described in claim 11, it is possible to widen the color gamut reproduced by the image forming apparatus as compared with the case where only one of the secondary color regions is expanded with one colorant. According to the invention described in claim 12, it is possible to widen the color gamut reproduced by the image forming apparatus as compared with the case where only one of the secondary color regions is expanded with one colorant.

Brief Description of the Drawings

[0009] [Figure 1] It is a diagram showing a configuration example of a printing system used in an embodiment. [Figure 2] It is a diagram showing an example of the hardware configuration of a control device. [Figure 3] It is a diagram for explaining an example of an operation screen used for an instruction to generate a color chart. [Figure 4] This diagram illustrates a functional configuration example related to the generation of color charts implemented by the processor. (A) shows an example of the overall configuration, and (B) shows an example of the internal configuration of the patch data generation unit. [Figure 5] This diagram illustrates the relationship between the color and color gamut of pigments in a color space. [Figure 6] This flowchart illustrates an example of the processing steps performed through the function that generates a color chart. [Figure 7] This diagram illustrates an example where the phase difference between a spot color and a basic color falls below a threshold. [Figure 8] This diagram illustrates the relationship between the feature color that yields a negative result in Step 1 and the expanded secondary color gamut. [Figure 9] This diagram illustrates the relationship between feature colors and the expanded color gamut. [Figure 10] This diagram illustrates the relationship between the features that yield a positive result in Step 1 and the two expanded color gamuts. [Figure 11] This diagram illustrates other relationships between feature colors and extended color gamut. [Figure 12] This diagram illustrates examples of color chart output when two color gamuts are expanded by adding one spot color. (A) is a color chart of the color gamut reproduced in CMYK, (B) is a color chart of the color gamut reproduced in MYKP, and (C) is a color chart of the color gamut reproduced in CMYKP. [Figure 13] This diagram summarizes the relationship between the pattern data generated by the patch data generation unit and the featured colors. [Figure 14] This diagram illustrates a functional configuration example related to the generation of color conversion profiles implemented by the processor. [Figure 15] This diagram illustrates an example of the functional configuration of the profile generation unit. [Figure 16] This flowchart illustrates an example of the processing steps performed in the color gamut design department. [Figure 17]This diagram illustrates two examples of expanded color gamuts. (A) shows the expanded O region, and (B) shows the expanded V region. [Figure 18] This diagram shows two expanded color gamuts superimposed on each other. [Figure 19] This diagram shows the color gamut, including the basic color K (black). [Figure 20] Figure 19 shows the color gamut with the O region extended and the V region extended, with the line segments corresponding to the colors connecting the grid points that represent the same color, indicated by thick lines. [Figure 21] This diagram illustrates how the overlapping portion of the color gamut shown in Figure 20 is folded to one side. [Figure 22] This figure shows the color gamut shown in Figure 21 with the O region side, defined by the four vertices "M", "M+K", "M+P(O)+K", and "M+P(O)", removed. [Figure 23] This flowchart illustrates an example of the processing steps performed in the color separation unit. [Figure 24] This diagram illustrates the expansion of the color gamut according to this embodiment. [Modes for carrying out the invention]

[0010] Embodiments of the present invention will be described below with reference to the drawings. <System Configuration> Figure 1 shows an example of the configuration of the printing system 1 used in the embodiment. The printing system 1 shown in Figure 1 consists of a paper feeder 10, a printing device 20, a post-processing device 30, and a control device 40. Here, printing system 1 is an example of an image forming system, printing device 20 and control device 40 are examples of image forming devices, and control device 40 is an example of an information processing device.

[0011] The printing system 1 shown in Figure 1 is also called a production printer. However, printing system 1 is not limited to a production printer; it can also be a printer used in an office or a printer used at home. Office printers have functions such as scanning and sending / receiving faxes in addition to printing. The main difference between office printers and home printers is their performance.

[0012] The printing system 1 shown in Figure 1 has two paper feeders 10 connected in series. The paper feeder 10 is a device that supplies paper P to the printing device 20. In this embodiment, the paper feeder 10 contains cut paper. For example, the paper feeder 10 can hold 7,000 sheets of cut paper. However, the paper P stored in the paper feeder 10 is not limited to cut paper; it may also be roll paper. Paper P here is just one example of a medium.

[0013] The printing system 1 shown in Figure 1 has two printing devices 20 connected in series. In this embodiment, each printing device 20 has an engine (hereinafter also referred to as the "printing engine") that prints an image onto paper P using an electrophotographic method. The printing engine prints an image onto paper P through the processes of charging, exposure, development, transfer, and fixing. The printing engine is an example of a forming unit that uses multiple colorants to form an image on paper P. The printing device 20 uses four types of toner corresponding to basic colors and one or two types of toner corresponding to spot colors for printing. Toner is an example of a colorant. Images include not only so-called diagrams and photographs, but also text. In this embodiment, the printing device 20 has the function of printing on one side of the paper P, as well as the function of printing on both sides of the paper P. The paper P on which the image is printed is called a printed document.

[0014] The printing system 1 shown in Figure 1 has two post-processing units 30 connected in series. The post-processing units 30 are equipped with processes such as stacking (i.e., stacking), stapling, and binding. The control device 40 is a device that controls the movement of the printing device 20 and other devices. For example, the control device 40 controls the generation and printing of color charts, the generation of color conversion profiles, the management of print jobs, and RIP (=Raster Image Processor) processing. In Figure 1, the control device 40 is located on the top of the housing of the printing device 20, but it may also be located inside the housing of the printing device 20.

[0015] Figure 2 shows an example of the hardware configuration of the control device 40. The control device 40 shown in Figure 2 includes a processor 41, a ROM (Read Only Memory) 42 in which the BIOS (Basic Input Output System) and other data are stored, a RAM (Random Access Memory) 43 used as the work area of ​​the processor 41, an auxiliary storage device 44, a user interface 45, a communication interface 46, and an I / O 47. The various parts of the control device 40 are connected via buses and other signal lines 48.

[0016] The processor 41 is a device that performs various functions through the execution of a program. In this embodiment, the processor 41 realizes the various functions described above through program execution. The processor 41, ROM 42, and RAM 43 function as a computer. The auxiliary storage device 44 is, for example, a hard disk drive or semiconductor storage. Programs, print jobs, etc., are stored in the auxiliary storage device 44. The term "program" is used as a general term for OS (Operating System) and application programs.

[0017] The user interface 45 is an interface that accepts operations from a user using the printing device 20. The user interface 45 has an input section, such as operation buttons or a touch sensor that detects operations by the user's fingertips, and a display section, such as a liquid crystal display or an organic EL (=Electro-Luminescent) display.

[0018] The communication interface 46 is an interface for communicating with a terminal (not shown) operated by the user. The communication method of the communication interface 46 can be wired or wireless. The communication standard used for the communication interface 46 may be, for example, Ethernet®, Wi-Fi®, etc. I / O47 is a device used for communication between the processor 41 and the printing device 20, etc.

[0019] <Processing Function> The following describes the processing functions that the processor 41 implements through program execution. These processing functions consist of two parts: the function of generating a color chart and the function of generating a color conversion profile.

[0020] <Function to generate color charts> The function to generate a color chart is initiated through user interaction with the user interface 45. Figure 3 illustrates an example of the operation screen 451 used to instruct the generation of a color chart. The operation screen 451 includes an input field 452 for information about the toner to be used, an "OK" button 453 for confirming the input, and a "Cancel" button 454 for canceling the generation of the color chart. In this embodiment, toner is used as the colorant because the image is printed using an electrophotographic method. When printing an image using an inkjet method, information about the ink is input. Ink is also an example of a colorant.

[0021] The input field 452 shown in Figure 3 displays two options. One option corresponds to the case where only "basic colors" toner is used, and the other option corresponds to the case where "basic colors and spot colors" toner is used. Special features include secondary colors of the basic colors O (orange), G (green), and V (violet), as well as fluorescent colors such as fluorescent P (pink), fluorescent Y (yellow), and fluorescent C (cyan). The operation screen 451 shown in Figure 3 does not have an item for specifying the type of spot color, but an item for specifying the type of spot color may be added. In Figure 3, "Basic Colors and Spot Colors" is selected as the toner to be used.

[0022] Figure 4 illustrates an example of the functional configuration related to the generation of a color chart realized by the processor 41 (see Figure 2). (A) shows an example of the overall configuration, and (B) shows an example of the internal configuration of the patch data generation unit 411. The overall configuration shown in Figure 4(A) includes a patch data generation unit 411 and a color chart output unit 412. The patch data generation unit 411 is a functional unit that determines the area to expand the color gamut when generating a color chart, and the color chart output unit 412 is a functional unit that uses the generated patch data to output a color chart in which multiple patches are arranged in a matrix. Each patch is a rectangular area to which one color is associated.

[0023] The color chart output by the color chart output unit 412 may be output as data or as a printed document. When outputting a color chart as a printed document, the color chart output unit 412 provides data to the printing device 20. The printing device 20 then prints the color chart onto paper P. The completion of calibration of the printing device 20 at the time of printing the color chart is irrelevant.

[0024] As shown in Figure 4(B), the patch data generation unit 411 consists of a functional unit 411A that determines the area to expand the color gamut according to the color measurement value of a single toner color (hereinafter referred to as the "color gamut expansion area determination unit"), and a functional unit 411B that calculates the patch data that constitutes the color chart (hereinafter referred to as the "patch data calculation unit").

[0025] The color gamut expansion area determination unit 411A determines the area to expand the color gamut when "basic colors and spot colors" is selected on the operation screen 451 (see Figure 3), but does not expand the color gamut when "basic colors only" is selected. Depending on the colorants used, the color gamut expansion area determination unit 411A may have either one color gamut to expand or two color gamuts to expand.

[0026] Figure 5 illustrates the relationship between the color and color gamut of a colorant in a color space. The color space used in Figure 5 is L * a * b * This is a color space. Incidentally, the color gamut shown in Figure 5 is L * This is the color gamut viewed from the high-luminance side. Therefore, the horizontal direction is a * The axis is defined as the vertical direction, and b is defined as the vertical direction. * Use it as the axis. Figure 5 shows three axes corresponding to the three basic colors excluding K (black): C (cyan), M (magenta), and Y (yellow). The C-axis passes through the origin and the coordinate point of C (cyan). The M-axis passes through the origin and the coordinate point of M (magenta). The Y-axis passes through the origin and the coordinate point of Y (yellow). The origin is W (white).

[0027] These three axes divide the color space into three regions. One region is the area between the Y-axis and the M-axis. This region corresponds to the secondary color of Y and M and is called the O (orange) region. One region is the area between the C axis and the M axis. This region corresponds to the secondary colors of C and M and is called the V (violet) region. One region is the area between the C axis and the Y axis. This region corresponds to the secondary colors of C and Y and is called the G (green) region. The color gamut expansion area determination unit 411A determines that one or two of the O region, V region, and G region will be expanded into an expanded area.

[0028] <Processing details> Figure 6 is a flowchart illustrating an example of the processing steps performed through the function that generates a color chart. The processing procedure shown in Figure 6 is realized through the execution of a program by processor 41 (see Figure 2). In the diagram, the symbol S represents a step. Note that the processing procedure shown in Figure 6 assumes the use of toner corresponding to the spot color.

[0029] First, the processor 41 determines whether the difference in the color space between the spot color and any of the basic colors is less than a threshold (Step 1). The difference in the color space includes, for example, hue difference and color difference. Of these, the color difference is calculated as the distance between the two colors. The color difference is not limited to the distance in the plane as exemplified in Figure 5, but also L * It is calculated as a distance in three-dimensional space, including the direction of the axes. The phase difference is the difference in phase angles.

[0030] Figure 7 illustrates an example where the phase difference between a spot color and a base color is below a threshold. In the color space shown in Figure 7, O (orange) and fluorescent P (pink) are mapped as spot colors. Fluorescent P here is an example of a fourth colorant. In Figure 7, the phase difference between the coordinate point of fluorescence P and the M axis is less than the threshold θ. Incidentally, the phase differences between the coordinate point of fluorescence P and the Y axis and C axis are all greater than the threshold θ. On the other hand, O (orange) is a secondary color obtained by mixing M and Y in equal proportions. Therefore, in Figure 7, the coordinate point of O lies on the phase angle that divides the Y axis and the M axis. Consequently, the phase difference between the coordinate point of O and each axis is greater than the threshold θ.

[0031] For example, if the feature is O, the processor 41 obtains a negative result in step 1. If a negative result is obtained in step 1, the processor 41 determines that the color gamut to which the spot color belongs (the color gamut of secondary colors) will be extended by the spot color (step 2). Figure 8 illustrates the relationship between the feature color that yields a negative result in Step 1 and the color gamut of the expanded secondary color. Figure 8 assumes the case where the feature color is O (orange). In this case, the processor 41 determines that the O region to which O belongs is the region to be expanded. Of course, if the feature that yields a negative result in Step 1 is a different color, the expanded area will also be a different secondary color area.

[0032] Figure 9 illustrates the relationship between spot colors and the expanded color gamut. The spot colors shown in Figure 9 are assumed to be pigments for which a negative result is obtained in Step 1. Figure 9 shows that if the special color is O (orange), the O region is expanded; if the special color is G (green), the G region is expanded; and if the special color is V (violet), the V region is expanded. Figure 9 shows that the feature color O is close to a secondary color with Y=100 and M=100, meaning it belongs to the O region. Furthermore, it has been shown that G, as a characteristic color, is close to a secondary color with Y=100 and C=100, meaning it belongs to the G region. Furthermore, it has been shown that V, as a feature color, is close to a secondary color with C=100 and M=100, meaning it belongs to the V region.

[0033] Returning to the explanation of Figure 6. Once the color gamut to be extended is determined, the processor 41 generates pattern data (hereinafter also referred to as "extended pattern data") corresponding to the combination of three basic colors excluding the complementary color of the spot color and the representative color of the extended color gamut, and adds it to the CMYK pattern data (hereinafter also referred to as "basic pattern data") (step 3). The pattern data here is a set of combinations of values ​​for four colorants that reproduce the color corresponding to each coordinate point. In other words, once step 3 is executed, the pattern data will consist of two parts: basic pattern data and extended pattern data. Next, the processor 41 outputs a color chart of the basic colors and a color chart corresponding to one extended color gamut (step 4).

[0034] Next, we will explain the case where the feature is a fluorescent color. In this case, the processor 41 obtains a positive result in step 1. If a positive result is obtained in Step 1, the processor 41 determines that the two adjacent color gamuts (secondary color gamuts) that have the smallest difference in color space between the primary color and the spot color will be extended by the spot color (Step 5). Figure 10 illustrates the relationship between the feature color that yields a positive result in Step 1 and the two expanded color gamuts.

[0035] Figure 10 assumes the case where the feature color is fluorescent P (pink). In this case, the processor 41 determines that the difference between the coordinate point of the fluorescent P and the M axis is less than a threshold, and decides to expand the adjacent O region and V region on either side of the M axis into two regions. In Figure 10, the M toner, which defines the M axis, is an example of the first colorant. Furthermore, the Y toner, which defines the Y axis, is an example of a second colorant. In this case, the color that extends the O region is an example of a first color. Furthermore, C toner, which defines the C axis, is an example of a third colorant. In this case, the color that extends the V region is an example of a second color. Of course, if the feature that yields a positive result in Step 1 is a different color, the combination of the two areas that are expanded will also be different.

[0036] Figure 11 illustrates another relationship between spot colors and the extended color gamut. The spot colors shown in Figure 11 are assumed to be pigments for which a positive result is obtained in Step 1. Figure 11 shows that if the color of the pigment material that is close to the spot color is M (magenta), the O and V regions should be expanded; if the color of the pigment material that is close to the spot color is Y (yellow), the O and G regions should be expanded; and if the color of the pigment material that is close to the spot color is C (cyan), the G and V regions should be expanded.

[0037] For example, if the color of the pigment material that is close to the spot color is Y (yellow), then Y toner becomes an example of the first pigment material, M toner becomes an example of the second pigment material, and C toner becomes an example of the third pigment material. In this case, the color that expands the O area becomes an example of the first color, and the color that expands the G area becomes an example of the second color. For example, if the color of a pigment that is close to the spot color is C (cyan), then C toner becomes an example of the first pigment, M toner becomes an example of the second pigment, and Y toner becomes an example of the third pigment. In this case, the color that extends the G area becomes an example of the first color, and the color that extends the V area becomes an example of the second color.

[0038] Returning to the explanation of Figure 6. Once the color gamut to be extended is determined, the processor 41 generates two corresponding pattern data (i.e., "extended pattern data") for each of the two color gamuts to be extended and adds them to the CMYK pattern data (i.e., "basic pattern data") (step 6). In other words, when step 6 is executed, the pattern data consists of three pieces: the basic pattern data and two extended pattern data pieces. Next, the processor 41 outputs a color chart of the basic colors and a color chart corresponding to the two extended color gamuts (step 7).

[0039] Figure 12 illustrates an example of color chart output when two color gamuts are expanded by adding one spot color. (A) is a color chart of the color gamut reproduced in CMYK, (B) is a color chart of the color gamut reproduced in MYKP, and (C) is a color chart of the color gamut reproduced in CMKP. The color chart shown in Figure 12(A) represents a color chart in which patches representing the colors reproduced by C toner, M toner, Y toner, and K toner corresponding to the basic colors are arranged in a matrix. The color chart shown in Figure 12(A) is an example of the first color chart.

[0040] The color chart shown in Figure 12(B) represents a color chart in which patches representing the colors reproduced by M toner, Y toner, K toner, and fluorescent P toner, excluding C (cyan), which is the complementary color of the O region, are arranged in a matrix. The color chart shown in Figure 12(B) is an example of a second color chart. The color chart shown in Figure 12(C) represents a color chart in which patches representing colors reproduced by C toner, M toner, K toner, and fluorescent P toner, excluding Y (yellow), which is the complementary color of the V region, are arranged in a matrix. The color chart shown in Figure 12(C) is an example of a third color chart.

[0041] The color chart shown in Figure 12(A) is generated from basic pattern data. The color charts shown in Figure 12(B) and Figure 12(C) are generated using extended pattern data. As mentioned above, in color charts corresponding to extended pattern data, the color chart is generated using pigments for the basic colors excluding the complementary colors of the extended color gamut, and pigments corresponding to the spot colors for which the color gamut can be extended.

[0042] Figure 13 is a diagram summarizing the relationship between the pattern data generated by the patch data generation unit 411 (see Figure 4(A)) and the spot colors. First, if no special colors are used (selected as "none"), only the color chart corresponding to the basic pattern data will be output. If the special color is O (orange), two color charts will be output: one corresponding to the extended pattern data where C is replaced with the special color, and another corresponding to the basic pattern data.

[0043] In Figure 13, the colorant corresponding to the extended pattern data is represented as "MYK+O". The base color C is replaced with O. The "+" symbol here means that it is represented as a secondary color of the colors before and after the symbol. In other words, it means that it is represented as a secondary color of the color that can be represented by "MYK" and "O".

[0044] Similarly, when the spot color is G (green), two color charts are output: one corresponding to the extended pattern data where M is replaced by the spot color, and another corresponding to the basic pattern data. In Figure 13, the colorant corresponding to the extended pattern data is represented as "CYK+G". The basic color M is replaced by G. Similarly, when the spot color is V (violet), two color charts are output: one corresponding to the extended pattern data where Y is replaced by the spot color, and another corresponding to the basic pattern data. In Figure 13, the colorant corresponding to the extended pattern data is represented as "CMK+V". The basic color Y is replaced by V.

[0045] On the other hand, when the spot color is fluorescent P (pink), three color charts are output: an extended pattern data in which C is replaced with the spot color, an extended pattern data in which Y is replaced with the spot color, and the basic pattern data. In Figure 13, the colorant corresponding to the first extended pattern data is represented as "MYK + fluorescent P," and the colorant corresponding to the second extended pattern data is represented as "CMK + fluorescent P." Similarly, when the spot color is fluorescent yellow (Y), three color charts are output: an extended pattern data where C is replaced with the spot color, an extended pattern data where M is replaced with the spot color, and the basic pattern data. In Figure 13, the colorant corresponding to the first extended pattern data is represented as "MYK + fluorescent Y," and the colorant corresponding to the second extended pattern data is represented as "CYK + fluorescent Y."

[0046] Similarly, when the feature is fluorescent C (cyan), three color charts corresponding to the extended pattern data obtained by replacing the feature with M, the extended pattern data obtained by replacing the feature with Y, and the basic pattern data are output. In FIG. 13, the colorant corresponding to the first extended pattern data is represented as "CYK + fluorescent C", and the colorant corresponding to the second extended pattern data is represented as "CMK + fluorescent C".

[0047] As described above, in the case of this embodiment, depending on the difference in the phase space between the feature that can be used for printing and the basic colors, the maximum number of extended pattern data used when the color gamut can be extended by the feature is two. For example, as shown in FIG. 10, the extended pattern data corresponds to the extended color gamut. Therefore, when it is possible to use a feature with a small difference in phase space from the basic colors, by enabling the output of two extended pattern data, it becomes possible to expand the reproducible color gamut compared to the case where only one extended pattern data is output.

[0048] <Function for generating a profile for color conversion> The function for generating a profile for color conversion is started through the optical reading of a color chart. FIG. 14 is a diagram for explaining a functional configuration example related to the generation of a profile for color conversion realized by a processor 41 (see FIG. 2). In FIG. 14, a patch color measurement unit 421, a profile generation unit 422, a profile reading unit 423, and a color conversion unit 424 are shown.

[0049] The patch color measurement unit 421 is a functional unit that optically measures the colors of the color charts shown in FIGS. 12(A) to (C), for example. Specifically, it outputs a value (hereinafter also referred to as "color measurement value") that specifies the colors of the patches arranged in a matrix. For example, the patch color measurement unit 421 outputs, as the color measurement value, L * a * b * The coordinate values in the color space (L * , a * , b *) outputs. When reading the color of a patch using a colorimeter that directly reads trimetric stimuli close to the sensitivity of the human eye, the patch colorimeter 421 may be implemented as part of the functions of a colorimeter (not shown).

[0050] The profile generation unit 422 is a functional unit that generates a profile for reproducing the measured color using multiple toners. Here, the profile is a combination of toner values ​​used to reproduce a specific color. Figure 15 illustrates an example of the functional configuration of the profile generation unit 422. As shown in Figure 15, the profile generation unit 422 consists of a color gamut expansion area determination unit 422A, a functional unit (hereinafter referred to as the "color gamut design unit") 422B that designs the determined color gamut, and a functional unit (hereinafter referred to as the "color separation unit") 422C that calculates combinations of colorant values ​​to reproduce each color in the designed color gamut.

[0051] The color gamut extension area determination unit 422A here has the same function as the color gamut extension area determination unit 411A (see Figure 4(B)). Therefore, if the functions implemented by the processor 41 include the function of generating a color chart, the color gamut extension area determination unit 411A can be reused as the color gamut extension area determination unit 422A.

[0052] The color gamut design unit 422B is a functional unit that designs the outer boundaries of the expanded color gamut. In other words, the color gamut design unit 422B is a functional unit that designs the boundary between the two expanded color gamuts. The design of the color gamut boundary is used in Gamut Mapping when converting a color target (a color target specified by Japan Color® 2011 or Pantone®) to a color that can be reproduced by the printer if the target color is outside the printer's color gamut. When extending the color gamut of secondary colors individually, the existence of other adjacent color gamuts is not taken into consideration. As a result, it is unavoidable that the outer edges of the two extended color gamuts will overlap. If overlaps are left unaddressed, color gamut boundaries will be generated even within the color gamut, and the combination of color gamut boundaries that should be converted using Gamut Mapping will not be uniquely determined. In other words, the profile will not be determined. Therefore, in this embodiment, the color gamut design unit 422B is used as a function to resolve the overlap of the outer edges of the two expanded color gamuts when it is possible to use special colors such as fluorescent P (pink).

[0053] The color separation unit 422C is a functional unit that searches for combinations of colorant values ​​that reproduce each color within the designed color gamut. The output of the color separation unit 422C is the profile. Returning to the explanation of Figure 14. The profile reading unit 423 is a functional unit that reads the profile generated by the profile generation unit 422 and provides it to the color conversion unit 424. The color conversion unit 424 is a functional unit that converts a combination of colorant values ​​that reproduces the specified color in the input data given as a print job into output data.

[0054] <Processing details> <Color Gamut Settings> Figure 16 is a flowchart illustrating an example of the processing procedure performed by the color gamut design unit 422B (see Figure 15). The processing procedure shown in Figure 16 is also realized through the execution of a program by processor 41 (see Figure 2). In the diagram, the symbol S stands for step. First, the processor 41 calculates the CMYK color gamut, which represents the basic colors (step 11). Colors within this color gamut are reproduced using C toner, M toner, Y toner, and K toner, and are therefore excluded from the expanded color gamut.

[0055] Next, the processor 41 expands one of the two color gamuts to be expanded (for example, the O region) (step 12). Next, the processor 41 expands the other of the two color gamuts to be expanded (for example, the V region) (step 13). Subsequently, the processor 41 removes the common area between the two expanded color gamuts (step 14). The common area is the color gamut that represents the same color.

[0056] Figures 17 to 22 are used to illustrate the process corresponding to steps 11 to 14. Figure 17 illustrates two examples of expanded color gamuts. (A) shows the expanded O region, and (B) shows the expanded V region. Note that the hexagonal areas shown in Figures 17(A) and (B) represent the color gamut that can be reproduced using three of the basic colors excluding K (black). Therefore, the extended color gamut refers to the color gamut excluding the hexagonal areas.

[0057] Incidentally, in the diagram, "Y+M" corresponds to O (orange), "Y+C" corresponds to G (green), and "M+C" corresponds to V (violet). Additionally, the "W" at the center of the hexagon represents the color white. As can be seen by comparing Figures 17(A) and (B), there is an overlap of extended color spaces around M (magenta).

[0058] Figure 18 is a diagram showing the two extended color gamuts superimposed. In Figure 18, the overlapping area between the color gamut shown in Figure 17(A) and the color gamut shown in Figure 17(B) is indicated by shading. The color gamut design unit 422B in this embodiment resolves this overlapping area. Figure 19 shows the color gamut, including the basic color K (black). Note that in Figure 19, the hue representation in Figure 18 has been rotated clockwise to account for the symmetry of the color gamut. Therefore, the 12 o'clock position corresponds to "Y+C" and "Y+C+K," and the 6 o'clock position corresponds to "M" and "M+K." Consequently, the shaded area representing the overlap of the color gamut is located approximately between 5 and 7 o'clock.

[0059] Figure 20 shows, with thick lines, the line segments corresponding to the colors that connect the grid points representing the same color in the color gamut extended from the O region and the color gamut extended from the V region, as shown in Figure 19. At the top of the thick line, starting from the 12 o'clock position and moving clockwise, are M (magenta), M+P(O), M+P(O)+K, M+K, M+P(V)+K, and M+P(V). Figure 21 illustrates how the overlapping portion of the color gamut shown in Figure 20 is folded to one side.

[0060] Specifically, in Figure 21, the V-region side, defined by the four vertices "M", "M+K", "M+P(V)+K", and "M+P(V)" in Figure 20, is folded into the O-region side, defined by the four vertices "M", "M+K", "M+P(O)+K", and "M+P(O)". Figure 22 shows the color gamut shown in Figure 21 with the O region side, defined by the four vertices "M", "M+K", "M+P(O)+K", and "M+P(O)", removed. Figure 22 shows the two expanded color gamuts, where the overlap between color gamuts has been resolved, enclosed by dashed lines. The right side represents the color gamut with the O region expanded, and the left side represents the color gamut with the V region expanded.

[0061] <Color decomposition> Figure 23 is a flowchart illustrating an example of the processing procedure performed in the color separation unit 422C (see Figure 15). The processing procedure shown in Figure 23 is also realized through the execution of a program by processor 41 (see Figure 2). In the diagram, the symbol S stands for step. Note that the process shown in Figure 23 is executed for each color designated as the target of the process, i.e., for each specific coordinate point.

[0062] First, processor 41 determines the value of K (step 21). Next, the processor 41 determines whether the color to be processed belongs to one of the two extended color gamuts (step 22). For example, it determines whether it belongs to either the extended O region or the V region as explained in Figure 22. If a negative result is obtained in step 22, the processor 41 sets the value of K to a fixed value and searches for each CMY value that satisfies the Lab value (step 23).

[0063] On the other hand, if a positive result is obtained in step 22, the processor 41 determines the spot color values ​​for the two expanded color regions (step 24). For example, in the case of a color belonging to region O, the value of fluorescent P (pink) is determined in region O enclosed by the dashed line in Figure 22. Next, the processor 41 sets the K value and the feature value as fixed values ​​and searches for each CMY value that satisfies the Lab value (step 25). The profile is determined through the above process.

[0064] <Summary> As described above, by using the control device 40 described in this embodiment, when printing is possible with a special color toner that has a small difference in the phase interval with any of the three basic colors excluding K (black), the color gamut that can be reproduced by the printing device 20 (see Figure 1) can be expanded. Figure 24 illustrates the expansion of the color gamut according to this embodiment. It can be seen that the color gamut shown in Figure 24 is wider than the color gamut shown in Figure 17(A) or (B). In other words, compared to methods where only one secondary color gamut is extended by a single spot toner, it becomes possible to further enhance the expressive power of printing using spot toners.

[0065] <Other Embodiments> (1) Although embodiments of the present invention have been described above, the technical scope of the present invention is not limited to the embodiments described above. It is clear from the claims that embodiments with various modifications or improvements made to those described above are also included in the technical scope of the present invention.

[0066] (2) In the above embodiment, L * a * b * We have explained the expansion of the color gamut and the generation of related color charts when using fluorescent pink (P) and other fluorescent toners, using color spaces as examples, but the color space is L * a * b * This is not limited to color spaces. (3) In the embodiments described above, fluorescent colors were given as examples of special colors that have a small difference in color space from any of the basic colors except K (black), but it is not necessary to limit the special colors to fluorescent colors. Also, even when the special color is a fluorescent color, it is not limited to the three colors mentioned above, namely fluorescent P, fluorescent Y, and fluorescent C.

[0067] (4) In the embodiment described above, the color value of the spot color is determined in step 24 (see Figure 23). However, the value of an intermediate color between the color of a pigment with a small difference in color space from the spot color and the color of another pigment may be determined, and then the color values ​​of the remaining pigments may be determined, and the value of the intermediate color may be determined as the value of the spot color. For example, if M (magenta) is the color of the first pigment and Y (yellow) is the color of the second pigment, O (orange), which is the intermediate color between the two pigments, is an example of the first intermediate color. Also, if M (magenta) is the color of the first pigment and C (cyan) is the color of the third pigment, V (violet), which is the intermediate color between the two pigments, is an example of the second intermediate color. In this calculation method, the intermediate color is a color that can be expressed using the basic color. Therefore, there are effectively only four parameters, and the computational load is reduced.

[0068] (5) The processor in each of the embodiments described above refers to a processor in a broad sense, and includes not only general-purpose processors (e.g., CPUs) but also specialized processors (e.g., GPUs (=Graphical Processing Units), ASICs (=Application Specific Integrated Circuits), FPGAs (=Field Programmable Gate Arrays), programmable logic devices, etc.). Furthermore, the processor operations in each of the embodiments described above may be performed by a single processor alone, or by multiple processors located in physically separate locations working together. Also, the order in which each operation is executed by the processor is not limited to the order described in each of the embodiments described above, but may be changed individually. [Explanation of Symbols]

[0069] 1…Printing system, 10…Paper feeder, 20…Printing device, 30…Post-processing unit, 40…Control unit, 41…Processor, 44…Auxiliary storage device, 411…Patch data generation unit, 411A…Color gamut expansion area determination unit, 411B…Patch data calculation unit, 412…Color chart output unit, 421…Patch colorimetric unit, 422…Profile generation unit, 422A…Color gamut expansion area determination unit, 422B…Color gamut design unit, 422C…Color separation unit, 423…Profile reading unit, 424…Color conversion unit

Claims

1. It has a processor, The aforementioned processor, When the difference in distance or phase difference in color space between the first colorant, the second colorant, the third colorant, and the first colorant is less than a threshold for that difference, the use of a fourth colorant is possible. Outputs a combination of colorant values ​​that reproduces a first color that expands the color gamut of the secondary colors between the first and second colorants, and a second color that expands the color gamut of the secondary colors between the first and third colorants. Information processing device.

2. The aforementioned processor, For the first color, the combination of values ​​for the first colorant, the second colorant, and the fourth colorant is output. For the second color, output the combination of values ​​for the first colorant, the third colorant, and the fourth colorant. The information processing apparatus according to claim 1.

3. The first color gamut and the second color gamut are defined as connected color gamuts that do not overlap with each other. The information processing apparatus according to claim 2.

4. The aforementioned processor, After determining the value of the fourth colorant that reproduces the first or second color, a combination of the value of the first colorant, the value of the second colorant, and the value of the third colorant is determined. The information processing apparatus according to claim 1.

5. The aforementioned processor, When outputting a combination of colorants that reproduces the first color, First, determine the value of the first intermediate color between the color of the first colorant and the color of the second colorant. Next, the first intermediate color is treated as a fixed value, and the combination of the value of the first colorant and the value of the second colorant is determined. Finally, the value of the first intermediate color is determined to be the value of the fourth colorant. The information processing apparatus according to claim 4.

6. The aforementioned processor, When outputting a combination of colorants that reproduces the second color, First, determine the value of the second intermediate color between the color of the first colorant and the color of the third colorant. Next, the value of the second intermediate color is treated as a fixed value, and the combination of the value of the first colorant and the value of the third colorant is determined. Finally, the value of the second intermediate color is determined to be the value of the fourth colorant. The information processing apparatus according to claim 4.

7. The first colorant, the second colorant, and the third colorant correspond to basic colors excluding black. The fourth colorant corresponds to a fluorescent color. The information processing apparatus according to claim 1.

8. A forming unit that forms an image on a medium using multiple colorants, Processor and It has, The aforementioned processor, When the difference in distance or phase difference in color space between the first colorant, the second colorant, the third colorant, and the first colorant is less than a threshold for said difference, the fourth colorant can be used in the forming part. Outputs a combination of colorant values ​​that reproduces a first color that expands the color gamut of the secondary colors between the first and second colorants, and a second color that expands the color gamut of the secondary colors between the first and third colorants. Image forming apparatus.

9. An image forming apparatus that forms an image on a medium using at least a first colorant, a second colorant, a third colorant, and a fourth colorant, The information processing apparatus according to any one of claims 1 to 6 and An image forming system having the following features.

10. When the difference in distance or phase difference in color space between the first colorant, the second colorant, the third colorant, and the first colorant is less than a threshold for that difference, the use of a fourth colorant is possible. On the computer, A function that outputs a combination of color material values ​​that reproduces a first color that expands the color gamut of the secondary colors between the first and second color materials, and a second color that expands the color gamut of the secondary colors between the first and third color materials. A program to achieve this.

11. It has a processor, The aforementioned processor, When the difference in distance or phase difference in color space between the first colorant, the second colorant, the third colorant, and the first colorant is less than a threshold for that difference, the use of a fourth colorant is possible. A first color chart is provided, which displays the colors reproduced by combinations of the first colorant, the second colorant, and the third colorant. A second color chart is provided, which displays the colors reproduced by the combination of the first color material's color, the second color material's color, and the fourth color material's color. A third color chart is generated, which arranges the colors reproduced by the combination of the first color material's color, the third color material's color, and the fourth color material's color. Information processing device.

12. When the difference in distance or phase difference in color space between the first colorant, the second colorant, the third colorant, and the first colorant is less than a threshold for that difference, the use of a fourth colorant is possible. On the computer, A function to generate a first color chart in which the colors reproduced by the combination of the first color material's color, the second color material's color, and the third color material's color are arranged, A function to generate a second color chart in which the colors reproduced by the combination of the first color material's color, the second color material's color, and the fourth color material's color are arranged, A function to generate a third color chart in which the colors reproduced by the combination of the first color material's color, the third color material's color, and the fourth color material's color are arranged, A program to achieve this.

Images