Image forming apparatus, image forming method, and program

Abstract

To provide an image forming apparatus, an image forming method, and a program that can prevent the occurrence of an unintentional difference of output color.SOLUTION: The present invention is an image forming apparatus that converts a spot color into a process color and outputs the process color, and the image forming apparatus comprises: a spot color information acquisition unit that acquires the name of the spot color and alternative color information in print data; a spot color color value information storage unit that stores color value information corresponding to the spot color; a color difference calculation unit that calculates color difference information between the alternative color information acquired by the spot color information acquisition unit and the color value information stored in the spot color color value information storage unit; a warning display unit that, on the basis of the color difference information calculated by the color difference calculation unit, indicates the fact that there is a possibility that the spot color in the print data may not be output as expected.SELECTED DRAWING: Figure 1

Description

[Technical field]

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

[0002] Spot colors, also called special colors, are inks that are premixed to express colors that cannot be reproduced using process colors such as CMYK in printing, and each ink is given a unique name and number. Major spot colors include PANTONE (special colors provided by PANTONE Inc., registered trademark), DIC (special colors provided by DIC Corporation, registered trademark), and TOYO (special colors provided by Toyo Ink Co., Ltd., registered trademark).

[0003] In digital printing such as electrophotography and inkjet, generally only process colors are used in many cases, so spot colors must be reproduced by mixing process colors. Also, when displaying data specified with spot colors on a monitor, the colors must be reproduced in the monitor's RGB. For this reason, DTP software or printing software incorporates color information such as L*a*b* for each spot color received under license from the spot color manufacturer, and spot color matching technology has been devised to convert the colors into the device output colors using ICC profiles, etc. for display or printing.

[0004] However, color value information such as L*a*b* varies depending on the spot color acquisition conditions, such as standard light source, viewing conditions, and measurement lighting conditions, so spot color manufacturers may provide L*a*b* for each standard light source, viewing condition, and measurement lighting condition.

[0005] Patent Document 1 discloses a configuration in which, in cases where an image area which is ultimately to be printed using a spot color material is specified with specified RGB values, the RGB values ​​are checked to see whether they are used to specify an image area in which a spot color material is to be used is not also used in an image area in which a spot color material is not to be used (in which it is to be printed in CMYK), and if a spot color material is used in an image area printed in CMYK, nearby RGB values ​​are searched for and made replaceable, for the purpose of preventing the spot color material from being used in an image area which has the same RGB values ​​and which it is to be printed using CMYK color materials rather than the spot color material, while enabling the display to be displayed using RGB values ​​which are reasonably close to the spot color material. Summary of the Invention [Problem to be solved by the invention]

[0006] However, in spot color matching, it is not specified which standard light source, viewing conditions, and measurement lighting conditions of color value information such as L*a*b* to use, so the color value information included may differ between DTP software and printing software. In such cases, the colors seen on the monitor may not match the printed colors, or the colors may be printed differently depending on the printing device.

[0007] The present invention has been made in consideration of the above, and has an object to provide an image forming apparatus, an image forming method, and a program that can prevent unintended differences in output colors from occurring. [Means for solving the problem]

[0008] In order to solve the above-mentioned problems and achieve the object, the present invention is an image forming device that converts a spot color into a process color and outputs the process color, and includes a spot color information acquisition unit that acquires a name and alternative color information of the spot color in print data, a spot color color value information storage unit that stores color value information corresponding to the spot color, a color difference calculation unit that calculates color difference information between the alternative color information acquired by the spot color information acquisition unit and the color value information stored in the spot color color value information storage unit, and a warning display unit that indicates, based on the color difference information calculated by the color difference calculation unit, that the spot color in the print data may not be output as expected. Effect of the Invention

[0009] According to the present invention, it is possible to prevent unintended differences in output colors from occurring. [Brief description of the drawings]

[0010] [Figure 1] FIG. 1 is a block diagram showing a schematic configuration example of an image forming apparatus 100 according to the present embodiment. [Diagram 2] FIG. 2 is a block diagram showing an example of a hardware configuration of the image forming apparatus according to the present embodiment. [Diagram 3] FIG. 3 is a diagram illustrating an example of a functional configuration of a DFE according to the present embodiment. [Figure 4] FIG. 4 is a diagram showing an example of color value information of a spot color on DTP software. [Diagram 5] FIG. 5 is a diagram showing an example of substitute color information for a spot color on a PDF. [Figure 6] FIG. 6 is a diagram showing an example of color value information of a spot color on the printing software. [Figure 7] FIG. 7 is a diagram showing an example of color value information for each spot color acquisition condition. [Figure 8] FIG. 8 is a diagram showing an example of color difference information calculated by the color difference calculation unit for an arbitrary spot color (for example, Test Color 1). [Figure 9A] FIG. 9A is a flowchart showing an example of the flow of color conversion processing in the DFE of the image forming apparatus according to the present embodiment. [Figure 9B] FIG. 9B is a flowchart showing an example of the flow of color conversion processing in the DFE of the image forming apparatus according to the present embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of an image forming apparatus, an image forming method, and a program will be described in detail with reference to the accompanying drawings.

[0012] Fig. 1 is a block diagram showing a schematic configuration example of an image forming apparatus 100 according to the present embodiment. As shown in Fig. 1, the image forming apparatus 100 is configured by connecting a control device (DFE: Digital Front End) 10 and a printer machine 20.

[0013] The DFE 10 communicates with the printer 20 and controls the formation of images in the printer 20. A PC (Personal Computer) 30 is also connected to the DFE 10. The DFE 10 may be connected to the PC 30 via a network. The PC 30 creates image information written in a language such as PDL using a pre-installed application, and transmits the created image information to the DFE 10. The DFE 10 converts the image information written in a language such as PDL into image data drawn in a format printable by the printer 20, and transmits the image data to the printer 20.

[0014] The hardware configuration of the DFE10 includes a CPU (Central Processing Unit) that controls the entire device, a main memory unit such as a ROM (Read Only Memory) and a RAM (Random Access Memory) that stores various data and programs, and an auxiliary memory unit such as a HDD (Hard Disk Drive) that stores various data and programs, and is a hardware configuration using a normal computer. The various processes in the DFE10 are realized by the CPU of the DFE10 executing various programs stored in the main memory unit and the auxiliary memory unit. However, this is not limited to this, and these functions can also be realized by individual circuits (hardware).

[0015] The printer 20 is equipped with at least one color of color material (cyan, magenta, yellow, black, etc.), and is also equipped with an image forming unit and a fixing mechanism for fixing the color material. The printer 20 creates and fixes an image using the color material in accordance with the image data transmitted from the DFE 10. In this way, an image is formed on the recording medium, and the desired printed matter 40 is obtained.

[0016] This embodiment may be implemented only by the DFE 10, or may be implemented only by the printer device 20. The printer device 20 may be implemented using either an electrophotographic printer and toner, or an inkjet printer and ink.

[0017] Fig. 2 is a block diagram showing an example of a hardware configuration of an image forming apparatus according to the present embodiment. As shown in Fig. 2, the image forming apparatus 100 is configured by connecting a controller (DFE) 10 and an engine unit (printer machine) 20 via a PCI (Peripheral Component Interface) bus. The controller 10 is a controller that controls the entire image forming apparatus 100 and controls drawing, communication, and input from an operation unit. The engine unit 20 is a printer engine or the like that can be connected to the PCI bus, such as an electrophotographic printer or an inkjet printer.

[0018] The controller 10 includes a CPU 11, a north bridge (NB) 13, a system memory (MEM-P) 12, a south bridge (SB) 14, a local memory (MEM-C) 17, an ASIC (Application Specific Integrated Circuit) 16, and a hard disk drive (HDD) 18, with the north bridge (NB) 13 and the ASIC 16 connected via an AGP (Accelerated Graphics Port) bus 15. The MEM-P 12 further includes a ROM (Read Only Memory) 12a and a RAM (Random Access Memory) 12b.

[0019] The CPU 11 performs overall control of the image forming apparatus 100, has a chipset consisting of NB13, MEM-P12, and SB14, and is connected to other devices via this chipset. The NB13 is a bridge for connecting the CPU 11 with the MEM-P12, SB14, and AGP15, and has a memory controller that controls reading and writing to the MEM-P12, a PCI master, and an AGP target.

[0020] MEM-P12 is a system memory used as a memory for storing programs and data, a memory for expanding programs and data, a printer drawing memory, etc., and is composed of ROM 12a and RAM 12b. ROM 12a is a read-only memory used as a memory for storing programs and data, and RAM 12b is a writable and readable memory used as a memory for expanding programs and data, a printer drawing memory, etc.

[0021] The SB14 is a bridge for connecting the NB13 to PCI devices and peripheral devices. The SB14 is connected to the NB13 via a PCI bus, and a network interface (I / F) unit and the like are also connected to the PCI bus.

[0022] The ASIC 16 is an IC (Integrated Circuit) for image processing purposes having hardware elements for image processing, and serves as a bridge connecting the AGP 15, PCI bus, HDD 18, and MEM-C 17. The ASIC 16 is composed of a PCI target and AGP master, an arbiter (ARB) that is the core of the ASIC 16, a memory controller that controls the MEM-C 17, a plurality of DMACs (Direct Memory Access Controllers) that rotate image data using hardware logic, and a PCI unit that transfers data between the engine unit 20 and the ASIC 16 via the PCI bus. A FCU (Facsimile Control Unit) 60, a USB (Universal Serial Bus) 70, and an IEEE1394 (the Institute of Electrical and Electronics Engineers 1394) interface 80 are connected to the ASIC 16 via the PCI bus. The operation display unit 50 is directly connected to the ASIC 16.

[0023] The MEM-C 17 is a local memory used as an image buffer for copying and a code buffer, and the HDD (Hard Disk Drive) 18 is a storage for storing image data, programs, font data, and forms.

[0024] The AGP 15 is a bus interface for a graphics accelerator card proposed to speed up graphic processing, and directly accesses the MEM-P 12 at high throughput to speed up the graphics accelerator card. This embodiment is realized by executing a program in the CPU 11, and data required by the program is stored in the RAM 12b or the like. Note that this hardware configuration diagram is an example, and a different configuration may be used as long as the hardware configuration can realize this embodiment.

[0025] Fig. 3 is a diagram showing an example of the functional configuration of a DFE according to the present embodiment. In the present embodiment, DFE 10 has a first color conversion unit 101, a second color conversion unit 102, a halftone engine 103, a spot color value difference warning and color value correction processing unit 104, and a spot color value information storage unit 105, as shown in Fig. 3.

[0026] The first color conversion unit 101 has a spot color conversion unit 101A. The spot color conversion unit 101A performs processing such as language interpretation, vector and raster conversion (rendering resolution is, for example, 1200 dpi), and color conversion to process colors (for example, CMYK) on an electronic document (print data) created by the PC 30.

[0027] Specifically, spot color conversion unit 101A is an example of a spot color conversion unit that performs color conversion processing on spot colors in print data using color value information stored in spot color color value information storage unit 105, which will be described later. At that time, spot color conversion unit 101A performs color conversion using color value information determined by spot color color value determination unit 104D, which will be described later. As a result, when there are multiple candidates for color value information to be converted from the spot color, it is possible to output using appropriate color value information.

[0028] The second color conversion unit 102 performs tone correction for calibration, total amount regulation for restricting the total amount of color materials, and the like.

[0029] The halftone engine 103 converts the 8-bit data for each color into the image data format of the printer device 20 (for example, 2 bits for each color), and sends the converted image data to the printer device 20.

[0030] Next, a detailed description will be given of an example of spot color color value difference warning and color value correction processing unit 104. Spot color color value difference warning and color value correction processing unit 104 has spot color information acquisition unit 104A, color difference calculation unit 104B, warning display unit 104C, spot color color value determination unit 104D, and spot color condition specification unit 104E. Spot color information acquisition unit 104A is an example of a spot color information acquisition unit that analyzes print data (e.g., PDF, PostScript) before being processed by first color conversion unit 101, acquires names of spot colors used in the print data and substitute color information for each spot color, and sends the acquired information to color difference calculation unit 104B.

[0031] Color difference calculation unit 104B acquires color value information held in DFE 10 corresponding to the name of the spot color sent from spot color information acquisition unit 104A from spot color color value information storage unit 105, and calculates color difference information for each spot color based on the acquired color value information and the above-mentioned alternative color information. In other words, color difference calculation unit 104B is an example of a color difference calculation unit that calculates color difference information between the alternative color information acquired by spot color information acquisition unit 104A and the color value information stored in spot color color value information storage unit 105.

[0032] Although there is one substitute color information for each spot color in the print data, the spot color color value information storage unit 105 may hold color value information for each condition (hereinafter, referred to as spot color acquisition condition) including at least one of the standard light source, the observation condition, and the measurement illumination condition of the spot color. In this case, the color difference calculation unit 104B calculates color difference information between the color value information for each spot color acquisition condition and the substitute color information. After that, the color difference calculation unit 104B sends the calculated color difference information to the warning display unit 104C and the spot color color value determination unit 104D. The spot color color value information storage unit 105 is an example of a spot color color value information storage unit that stores color value information corresponding to a spot color.

[0033] The warning display unit 104C is an example of a warning display unit that displays (warning display) that the spot color in the print data may not be output as expected based on the color difference information calculated by the color difference calculation unit 104B. This makes it possible to prevent unintended differences in output color by comparing the alternative color information linked to the spot color in the print data with the color value information of the spot color installed in the printing device and issuing a warning if there is a difference or correcting the color value information such as L*a*b* to be used.

[0034] Specifically, when the color difference information calculated by color difference calculation unit 104B is not 0, that is, when there is a difference between the substitute color information of the spot color in the print data and the color value information in spot color value information storage unit 105, warning display unit 104C displays a warning that the spot color in the print data may not be output as expected. In this case, printing may be continued after the warning is displayed, or the user may be prompted to instruct whether to continue or stop printing. Furthermore, warning display unit 104C may not display a warning when the color difference information calculated by color difference calculation unit 104B is equal to or less than a certain value. This makes it possible to prevent the spot color in the print data from being output in an unintended color.

[0035] If the substitute color information for a spot color in the print data is specified in a device-dependent color space such as RGB and CMYK, rather than in a device-independent color space such as L*a*b* and XYZ, and color difference calculation unit 104B is unable to calculate color difference information, a warning may be displayed in warning display unit 104C, and the color value information held in spot color color value information storage unit 105 may be used.

[0036] That is, the warning display unit 104C may display a warning when the color value information of the substitute color information of the spot color in the print data is device-dependent color value information such as RGB and CMYK and the color difference calculation unit 104B cannot calculate the color difference information, and when the color difference calculation unit 104B cannot calculate the color difference information because there is no color value information in the spot color color value information storage unit 105. This makes it possible to prevent the spot color in the print data from being output in an unintended color.

[0037] In addition, when the color difference information is smaller than a predetermined value, that is, when the difference between the substitute color information of the spot color in the print data and the color value information in the spot color value information storage unit 105 is small, the warning display unit 104C may continue printing without displaying a warning.

[0038] When printing is continued after displaying the warning, the spot color value determination unit 104D determines the color value information to be used for each spot color, and sends the determined color value information to the spot color conversion unit 101A. There are two main methods for determining the color value information to be used: one is to use substitute color information for the spot color in the print data, and the other is to use color value information from the spot color color value information storage unit 105. When the spot color color value information storage unit 105 holds color value information for each spot color acquisition condition for one spot color, the color value information with the smallest calculated color difference information may be adopted, or the spot color condition designation unit 104E may receive designation of the spot color acquisition condition from the user and determine the color value information. In either case, the possibility of outputting a color different from the expected color can be reduced.

[0039] That is, spot color color value determination unit 104D is an example of a spot color value determination unit that determines which color value information to use when spot color color value information storage unit 105 stores multiple color value information corresponding to spot color acquisition conditions for various spot colors. For example, spot color color value determination unit 104D may determine to use color value information for which the color difference information calculated by color difference calculation unit 104B is the smallest among the color value information for each spot color acquisition condition. This makes it possible to output a color closest to the alternative color information in the print data when there are multiple candidates for color value information to be converted from a spot color, and to prevent the spot color in the print data from being output in an unintended color.

[0040] Furthermore, if the color difference information calculated by color difference calculation unit 104B is 0, that is, if there is no difference between the alternative color information of the spot color in the print data and the color value information in spot color value information storage unit 105, warning display unit 104C does not display a warning, and spot color color value determination unit 104D decides to use the same color value information as the alternative color information, and sends the decided color value information to spot color color conversion unit 101A.

[0041] In addition, if spot color color value information storage unit 105 holds color value information for each spot color acquisition condition for one spot color, and one of the spot color acquisition conditions has color difference information with respect to the alternative color information of the spot color in the print data that is 0, while the other spot color acquisition conditions have color difference information that is not 0, printing may be performed using the color value information with color difference information of 0 without displaying a warning, or the spot color acquisition condition for the color value information to be used may be displayed, and printing may be performed based on the user's instructions.

[0042] Furthermore, if spot color color value information storage unit 105 holds color value information for each spot color acquisition condition for one spot color, spot color color value determination unit 104D may determine color value information upon receiving designation of spot color acquisition conditions from the user at spot color condition designation unit 104E, as described above. That is, spot color color value determination unit 104D may determine to use color value information of the spot color acquisition conditions designated at spot color condition designation unit 104E. In this way, if the user has desired spot color acquisition conditions, output can be unified to those spot color acquisition conditions.

[0043] In any case where the color difference information calculated by color difference calculation unit 104B is 0, other than 0, or cannot be calculated, spot color color value determination unit 104D may always use the color value information of the spot color acquisition conditions designated in advance by the user. Furthermore, when color difference calculation unit 104B cannot calculate color difference information, spot color value determination unit 104D may determine whether to use the substitute color information of the spot color in the print data or the color value information stored in spot color color value information storage unit 105, depending on the reason why color difference information cannot be calculated. This makes it possible to prevent the spot color in the print data from being output in an unintended color.

[0044] The spot color conversion unit 101A uses the color value information of the spot color sent from the spot color value determination unit 104D and performs color conversion on the color value information.

[0045] FIG. 4 is a diagram showing an example of color value information of a spot color on a DTP software. In the DTP software, a user can select a spot color from a swatch library and use the color for graphics, text, etc. In particular, corporate colors (company logos) are often specified as spot colors. Many users use spot colors while being aware only of their names, and rarely pay attention to the color value information (L*a*b*, etc.) of the spot color. However, in reality, in order to reproduce spot colors on a monitor, the DTP software holds color value information (L*a*b*, etc.) as shown in FIG. 4(a), and converts this color value information into RGB for the monitor for display. Although L*a*b*, which is a device-independent color space shown in FIG. 4(a), is generally used as the color value information of spot colors, it is also possible to specify device-dependent color spaces such as RGB and CMYK as shown in FIG. 4(b).

[0046] Figure 5 is a diagram showing an example of alternative color information for spot colors in a PDF. Documents designed using DTP software are often ultimately saved as PDFs. Figure 5 shows spot color information in a PDF confirmed using the preflight function of PDF viewing and editing software. In the example in Figure 5, we can see that a spot color named PANTONE Yellow 012 C is being used.

[0047] Basically, a spot color is uniquely determined by its name and number, but except when using the ink of that spot color, not only the name and number but also the L*a*b* of the spot color is required for displaying on a monitor in RGB and printing in process colors such as CMYK. This is because the monitor display and printing can be performed by converting this L*a*b* to RGB or CMYK. Therefore, in addition to the name and number of the spot color, color value information called alternative color information is also stored on the PDF. In the example of Figure 5(a), L*a*b* is used as the alternative color information, and when saving the PDF, the L*a*b* stored in the DTP software is used. There are cases where CMYK and RGB are used as the alternative color information instead of L*a*b*, and the example shown in Figure 5(b) is an example where the alternative color information is CMYK.

[0048] FIG. 6 is a diagram showing an example of color value information of spot colors on printing software. Since alternative color information is linked to spot colors in a PDF, printing itself is possible even if the L*a*b* of the spot color is not held on printing software such as DFE10. However, the color value information of the alternative color information linked to the spot color in the PDF is not necessarily appropriate. For example, it is possible to correctly specify only the name of the spot color and input appropriate color value information as the alternative color information. Therefore, DFE10 holds L*a*b* for various spot colors, and can perform color conversion using the L*a*b* for the spot color. FIG. 6 shows an example of L*a*b* for PANTONE Yellow 012 C held in DFE10.

[0049] FIG. 7 is a diagram showing an example of color value information for each spot color acquisition condition. DTP software and printing software are equipped with color value information for each spot color received from the spot color manufacturer, but in some cases, the spot color manufacturer provides color value information for each spot color acquisition condition. This is because color value information for the same spot color differs depending on the spot color acquisition condition. In this case, it is possible to only equip color value information for a specific spot color acquisition condition, or to equip color value information for multiple spot color acquisition conditions and specify the spot color acquisition condition for the color value information to be used. Since the color value information for spot colors differs depending on the spot color acquisition condition, if the color value information equipped and used differs between the DTP software and printing software, the output may be in a color different from what was expected.

[0050] Standard light sources are generally D50 or D65, with D50 often used in the printing industry. Observation conditions include 2° and 10° viewing angles, with 2° often used in the printing industry. Measurement lighting conditions include M0, M1, M2, and M3, with M1 becoming the mainstream in the printing industry, but M0 and M2 are also occasionally used, which can result in output colors that are different from what was expected.

[0051] The example shown in Fig. 7 illustrates the L*a*b* of spot color: Test Color 1 under each measurement illumination condition: M0, M1, M2, with a standard light source: D50, observation condition: 2° field of view, which is generally used in the printing industry. As shown in this example, L*a*b* differs for each spot color acquisition condition.

[0052] Some printing papers contain fluorescent whitening components to enhance the white color, but in the case of such papers, the difference between M2, which can measure by excluding the effects of the fluorescent whitening components (cutting UV components), and other conditions is large. Also, for color materials such as metallics, which change color depending on the viewing angle, the difference between M3, which can be measured by removing or reducing the effects of surface reflection with a polarizing filter, and other spot color acquisition conditions is large.

[0053] 8 is a diagram showing an example of color difference information calculated by the color difference calculation unit for an arbitrary spot color (for example, Test Color 1). Note that an example will be described in which the printing software (DFE10) is equipped with L*a*b* color value information for each measurement illumination condition: M0, M1, M2, D50, 2° field of view.

[0054] Fig. 8(a) shows an example in which color difference information ΔE2000 is calculated between L*a*b*, which is the alternative color information of a spot color in a PDF, and the L*a*b* of the same spot color installed in a DFE10, and there is no spot color acquisition condition in which the color difference information becomes 0. In this case, if the color value information is determined by a method of adopting the color value information that minimizes the color difference information as the color value information to be used for this spot color, it is sufficient to use L*a*b* with a measurement lighting condition of M0.

[0055] Fig. 8(b) shows an example where color difference information ΔE2000 is calculated between L*a*b*, which is the alternative color information of a spot color in a PDF, and the L*a*b* of the same spot color installed in the DFE10, and there is a spot color acquisition condition where the color difference information is 0. In this case, it is sufficient to use the L*a*b* of the measurement lighting condition: M2, where the color difference information is 0.

[0056] Figure 8(c) shows an example in which the alternative color information for a spot color in a PDF is CMYK, and color difference information cannot be calculated with the L*a*b* of the same spot color in the DFE 10. Color difference information can be calculated if the CMYK alternative color information is converted to L*a*b* by some means, but because it is unclear what color value information the CMYK assumes for what spot color acquisition conditions, even if it is converted to L*a*b*, it may not be the expected color value information, so it is best to display a warning and let the user specify which spot color acquisition conditions L*a*b* to use.

[0057] Figure 8(d) shows a case where the DFE 10 does not have the same L*a*b* spot color as the spot color in the PDF. Since there are many types of spot colors and the number of colors is sometimes added through regular version upgrades, it is possible that the DFE 10 does not have the same L*a*b* spot color as the spot color used in the PDF. In this case, the only way to print is to use the alternative color information of the spot color in the PDF, so the alternative color information of the spot color in the PDF is used as the color value of the spot color.

[0058] 9A and 9B are flow charts showing an example of the flow of color conversion processing in the DFE of the image forming apparatus according to the present embodiment. When printing print data including spot colors, the spot color information acquisition unit 104A analyzes the print data (e.g., PDF, PostScript) before being processed by the first color conversion unit 101, acquires the names of the spot colors used in the print data and the substitute color information for each spot color, and sends them to the color difference calculation unit 104B (step S1001).

[0059] Color difference calculation unit 104B acquires color value information stored in DFE 10 that corresponds to the name of the spot color sent from spot color information acquisition unit 104A from spot color color value information storage unit 105, and calculates color difference information of each spot color based on the acquired color value information and the above-mentioned alternative color information (step S1002). After that, color difference calculation unit 104B sends the calculated color difference information to warning display unit 104C and spot color color value determination unit 104D.

[0060] Next, when color difference information is calculated (step S10: Yes) and there is no spot color acquisition condition with the color difference information of 0 (step S20: No), warning display unit 104C displays a message that there is a difference between the substitute color information of the spot color in the print data and the color value information of the spot color installed in DFE 10, and that the spot color in the print data may not be output as expected (step S1003). Also, when there is no designation of the color value information to be used (step S30: No), spot color color value determination unit 104D determines to use the color value information that minimizes the calculated color difference information, and sends the determined color value information to spot color color conversion unit 101A (step S1004).

[0061] If a spot color acquisition condition with color difference information of 0 exists (step S20: Yes) but color value information to be used has been specified (step S40: Yes, step S30: Yes), spot color color value determination unit 104D decides to use the specified color value information and sends the decided color value information to spot color conversion unit 101A (step S1005).

[0062] If a spot color acquisition condition with color difference information of 0 exists (step S20: Yes) and color value information to be used has not been specified (step S40: No), the color value information of the spot color acquisition condition with color difference information of 0, i.e., the same color value information as the alternative color information, should be used. Therefore, spot color color value determination unit 104D determines to use the same color value information as the alternative color information and sends the determined color value information to spot color color conversion unit 101A (step S1006).

[0063] If the color difference information cannot be calculated (step S10: No), warning display unit 104C displays a message indicating that the spot color in the print data may not be output as expected because color difference information between the alternative color information of the spot color in the print data and the color value information of the spot color installed in DFE10 cannot be calculated (step S1007).

[0064] If the alternative color information of the spot color in the print data is L*a*b* (step S50: No), the reason why the color difference information could not be calculated in step S10 is considered to be that the spot color has no color value information in the spot color color value information storage unit 105. For spot colors that have no color value information in the spot color color value information storage unit 105, the only way to perform color conversion is to use the alternative color information. Therefore, in this case, as in the above, in S1006, the spot color color value determination unit 104D determines to use the same color value information as the alternative color information, and sends the determined color value information to the spot color color conversion unit 101A (step S1006).

[0065] If the alternative color information of the spot color in the print data is other than L*a*b* (step S50: Yes) and there is no color value information in the spot color color value information storage unit 105 (step S60: No), the alternative color information of the spot color in the print data (for example, CMYK, RGB) must be color converted using a CMYK or RGB ICC profile or the like before outputting. In this case, as in the above, the spot color color value determination unit 104D determines to use the same color value information as the alternative color information, and sends the determined color value information to the spot color color conversion unit 101A (step S1006).

[0066] If the substitute color information of the spot color in the print data is other than L*a*b* (step S50: Yes) and color value information exists in the spot color color value information storage unit 105 (step S60: Yes), the use of the color value information existing in the spot color color value information storage unit 105 is less likely to result in an output color different from the expected color. Therefore, the spot color color value determination unit 104D determines to use the color value information of the spot color color value information storage unit 105, and sends the determined color value information to the spot color color conversion unit 101A (step S1008). If the spot color color value information storage unit 105 contains color value information of a plurality of spot color acquisition conditions, the user may be allowed to specify which color value information of the spot color acquisition conditions to use, or the spot color acquisition conditions to be used may be set in advance.

[0067] After the color value information to be used by the spot color color value determination unit 104D is determined, the spot color conversion unit 101A uses the color value information of the spot color sent from the spot color color value determination unit 104D and performs color conversion, etc., on the color value information using an ICC profile, etc. (step S1009).

[0068] In this way, according to the image forming apparatus 100 of the present embodiment, the alternative color information linked to the spot color in the print data is compared with the color value information of the spot color installed in the printing device, and if there is a difference, a warning is issued or the color value information such as L*a*b* used is corrected, thereby preventing unintended differences in output color.

[0069] The program executed by image forming apparatus 100 of this embodiment is provided by being pre-installed in ROM 12a etc. The program executed by image forming apparatus 100 of this embodiment may be provided by being recorded in a computer-readable recording medium such as a CD-ROM, a flexible disk (FD), a CD-R, or a digital versatile disk (DVD) in the form of an installable or executable file.

[0070] Furthermore, the program executed by image forming apparatus 100 of the present embodiment may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. Also, the program executed by image forming apparatus 100 of the present embodiment may be provided or distributed via a network such as the Internet.

[0071] The program executed by image forming apparatus 100 of this embodiment has a modular configuration including the above-mentioned sections (first color conversion section 101, second color conversion section 102, halftone engine 103, spot color color value difference warning and color value correction processing section 104), and in terms of actual hardware, a processor such as CPU 11 reads out the program from ROM 12a and executes it, thereby loading the above-mentioned sections onto the main memory device, and first color conversion section 101, second color conversion section 102, halftone engine 103, spot color color value difference warning and color value correction processing section 104 are generated on the main memory device.

[0072] In the above embodiment, the image forming apparatus 100 of the present invention is described as being applied to a multifunction device having at least two of the functions of a copy function, a printer function, a scanner function, and a facsimile function. However, the image forming apparatus can be applied to any image forming apparatus such as a copier, a printer, a scanner device, or a facsimile device.

[0073] For example, aspects of the present invention are as follows. <1> An image forming apparatus that converts a spot color into a process color and outputs the converted color, a spot color information acquisition unit that acquires the name of the spot color and alternative color information in the print data; a spot color value information storage unit that stores color value information corresponding to the spot color; a color difference calculation unit that calculates color difference information between the alternative color information acquired by the spot color information acquisition unit and the color value information stored in the spot color color value information storage unit; a warning display unit that displays a warning that the spot color in the print data may not be output as expected based on the color difference information calculated by the color difference calculation unit; An image forming apparatus comprising: <2> a spot color conversion unit that performs color conversion processing on the spot color in the print data using the color value information stored in the spot color color value information storage unit; a spot color value determining unit that determines which of the color value information is to be used when the spot color color value information storage unit stores a plurality of pieces of color value information corresponding to spot color acquisition conditions including at least one of a standard light source, a viewing condition, and a measurement illumination condition for each of the spot colors; the spot color conversion unit performs color conversion using the color value information determined by the spot color color value determination unit; <1> 2. The image forming apparatus according to claim 1 . <3> the spot color value determination unit determines to use the color value information that minimizes the color difference information calculated by the color difference calculation unit; <2> 2. The image forming apparatus according to claim 1 . <4> A spot color condition designation unit is further provided for allowing a user to designate the spot color acquisition conditions, the spot color value determination unit determines to use the color value information of the spot color acquisition condition designated by the spot color condition designation unit; <2> or <3> 2. The image forming apparatus according to claim 1 . <5> the warning display unit does not display a warning when the color difference information calculated by the color difference calculation unit is equal to or smaller than a certain value. <1> from <4> 13. The image forming apparatus according to claim 12, <6> the warning display unit displays a warning when the color value information of the substitute color information of the spot color in the print data is device-dependent color value information and the color difference calculation unit is unable to calculate the color difference information, and when the color value information does not exist in the spot color color value information storage unit and therefore the color difference calculation unit is unable to calculate the color difference information. <1> from <5> 13. The image forming apparatus according to claim 12, <7> When the color difference calculation unit is unable to calculate the color difference information, the spot color value determination unit determines whether to use the alternative color information of the spot color in the print data or the color value information stored in the spot color color value information storage unit, depending on the reason why the color difference information cannot be calculated. <2> from <6> 13. The image forming apparatus according to claim 12, <8> An image forming method carried out in an image forming apparatus, comprising: obtaining the name and alternative color information of the spot color in the print data; A step of calculating color difference information between the acquired alternative color information and color value information corresponding to the spot color stored in a spot color value information storage unit; indicating, based on the calculated color difference information, that the spot color in the print data may not be output as expected; An image forming method comprising the steps of: <9> Computer, a spot color information acquisition unit that acquires the name of the spot color and alternative color information in the print data; a color difference calculation unit that calculates color difference information between the alternative color information acquired by the spot color information acquisition unit and color value information corresponding to the spot color stored in a spot color color value information storage unit; a warning display unit that displays a warning that the spot color in the print data may not be output as expected based on the color difference information calculated by the color difference calculation unit; A program to make it function as such. [Explanation of symbols]

[0074] 10 DFE 11 CPU 12a ROM 12b RAM 20 Printer Machine 100 Image forming device 101 First color conversion unit 101A Spot color conversion unit 102 Second color conversion unit 103 Halftone Engine 104 Spot color value difference warning and color value correction processing section 104A Spot color information acquisition unit 104B Color difference calculation section 104C Warning display section 104D Spot color value determination unit 104E Spot color condition specification section 105 Spot color value information storage unit [Prior art documents] [Patent documents]

[0075] [Patent Document 1] JP 2011-244301 A

Claims

1. An image forming apparatus that converts a spot color into a process color and outputs the converted color, a spot color information acquisition unit that acquires the name of the spot color and alternative color information in the print data; a spot color value information storage unit that stores color value information corresponding to the spot color; a color difference calculation unit that calculates color difference information between the alternative color information acquired by the spot color information acquisition unit and the color value information stored in the spot color color value information storage unit; a warning display unit that displays a warning that the spot color in the print data may not be output as expected based on the color difference information calculated by the color difference calculation unit; An image forming apparatus comprising:

2. a spot color conversion unit that performs color conversion processing on the spot color in the print data using the color value information stored in the spot color color value information storage unit; a spot color value determining unit that determines which of the color value information is to be used when the spot color color value information storage unit stores a plurality of pieces of color value information corresponding to spot color acquisition conditions including at least one of a standard light source, a viewing condition, and a measurement illumination condition for each of the spot colors; 2. The image forming apparatus according to claim 1, wherein the spot color conversion section performs color conversion using the color value information determined by the spot color value determination section.

3. 3. The image forming apparatus according to claim 2, wherein the spot color value determining section determines to use the color value information that minimizes the color difference information calculated by the color difference calculating section.

4. A spot color condition designation unit is further provided for allowing a user to designate the spot color acquisition conditions, 4. The image forming apparatus according to claim 2, wherein the spot color value determination section determines to use the color value information of the spot color acquisition condition designated by the spot color condition designation section.

5. The image forming apparatus according to claim 1 , wherein the warning display unit does not display a warning when the color difference information calculated by the color difference calculation unit is equal to or smaller than a certain value.

6. 2. The image forming apparatus according to claim 1, wherein the warning display unit displays a warning when the color value information of the alternative color information of the spot color in the print data is device-dependent color value information and the color difference calculation unit is unable to calculate the color difference information, and when the color value information does not exist in the spot color color value information storage unit and therefore the color difference calculation unit is unable to calculate the color difference information.

7. 3. The image forming apparatus according to claim 2, wherein, when the color difference calculation unit is unable to calculate the color difference information, the spot color color value determination unit determines whether to use the alternative color information of the spot color in the print data or the color value information stored in the spot color color value information storage unit, depending on a reason why the color difference information cannot be calculated.

8. An image forming method carried out in an image forming apparatus, comprising: obtaining a name of a spot color and alternative color information in the print data; A step of calculating color difference information between the acquired alternative color information and color value information corresponding to the spot color stored in a spot color value information storage unit; indicating, based on the calculated color difference information, that the spot color in the print data may not be output as expected; An image forming method comprising the steps of:

9. Computer, a spot color information acquisition unit that acquires the name of a spot color and alternative color information in the print data; a color difference calculation unit that calculates color difference information between the alternative color information acquired by the spot color information acquisition unit and color value information corresponding to the spot color stored in a spot color color value information storage unit; a warning display unit that displays a warning that the spot color in the print data may not be output as expected based on the color difference information calculated by the color difference calculation unit; A program to make it function as such.

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