Image forming apparatus, method for controlling image forming apparatus, and program

Abstract

To achieve accurate spot color correction.SOLUTION: An embodiment of the present invention is an image forming apparatus having: receiving means that receives a first Lab value and a ΔLab value of a target color; generation means that uses a printer profile to generate image data of a layout in which a plurality of patch images are arranged on the basis of the first Lab value and the ΔLab value, in which the plurality of patch images each include an image part filled with a single color; formation means that forms the plurality of patch images on a recording medium on the basis of the image data of the layout; acquisition means that measures the colors of the image parts of the plurality of patch images formed by the formation means, to acquire second Lab values for the plurality of patch images; and determination means that determines, from the plurality of patch images, a patch image having the second Lab value closest to the first Lab value of the target color.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present disclosure relates to an image forming apparatus, a control method and a program for an image forming apparatus, and in particular to a technique for correcting colors by printing and measuring spot colors. [Background technology]

[0002] Some conventional recording devices have a spot color printing function for printing specific colors, such as desired corporate colors, with high reproducibility. However, depending on the recording device that prints the spot color, the desired color may not be reproduced due to the color characteristics of the recording device. To solve this problem, there is a spot color correction function that measures the color of the recording medium on which the spot color is printed to achieve color reproduction of the spot color according to the characteristics of the recording device.

[0003] Patent Document 1 discloses a technique for generating pixel values for patches printed for spot color correction from eight grid points around a target value in the B2A tag of an ICC profile. The B2A tag of an ICC profile is a table for converting, for example, Lab spot color values to CMYK in the color space of a recording device. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2006-157294 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in Patent Document 1, even if the user finds a color that they like among the colors indicated by the surrounding pixel values of a patch printed for spot color correction, the user cannot specify the pixel value of the patch, which poses a problem in that spot color correction cannot be performed with the desired accuracy.

[0006] In view of the above problems, an object of the present disclosure is to achieve highly accurate spot color correction. [Means for solving the problem]

[0007] One embodiment of the present invention is an image forming apparatus comprising: a receiving means for receiving a first Lab value and a ΔLab value of a target color; a generating means for generating image data of a layout in which a plurality of patch images are arranged based on the first Lab value and the ΔLab value using a printer profile, wherein the plurality of patch images each include an image portion filled with a single color; a forming means for forming the plurality of patch images on a recording medium based on the image data of the layout; an acquiring means for measuring the color of the image portion of each of the plurality of patch images formed by the forming means and acquiring a second Lab value for each of the plurality of patch images; a determining means for determining, from the plurality of patch images, a patch image whose second Lab value is closest to the first Lab value of the target color; and a setting means for setting the CMYK values of the patch image determined by the determining means as correction values for a spot color. [Effects of the Invention]

[0008] According to the present disclosure, highly accurate spot color correction can be achieved. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a diagram showing the configuration of an image forming system. [Figure 2] Block diagram of an image forming apparatus [Figure 3] GUI screen for spot color correction (color matching) [Figure 4] Diagram showing the relationship between target color and surrounding colors [Figure 5] FIG. 10 is a diagram showing patch images printed using device colors. [Figure 6] Flowchart of spot color correction (color matching) processing according to the first embodiment [Figure 7] Flowchart of spot color correction (color matching) processing according to the first embodiment [Figure 8] Flowchart of spot color correction (color matching) processing according to the second embodiment [Figure 9] GUI screen showing the results of spot color correction (color matching) DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present disclosure will be described in detail. Note that the components described below are merely examples and are not intended to limit the scope of the present disclosure.

[0011] [First embodiment] FIG. 1 is a diagram showing the configuration of an image forming system 1 according to this embodiment. The image forming system 1 forms images on roll paper P (also referred to as continuous paper) used in this embodiment, which is capable of continuous image formation. The image forming system 1 is configured by connecting, from upstream along the transport direction of the roll paper P, a paper feeder 10, an image forming device 20, and a winding device 30. The paper feeder 10 is a device that supplies the roll paper P to the image forming device 20. The paper feeder 10 rotates the paper core of the roll paper P around a rotation axis 11, and transports the roll paper P wound around the paper core toward the image forming device 20 at a constant speed via multiple rollers (e.g., transport rollers, paper feed rollers, etc.). The image forming device 20 forms an image on the roll paper P supplied from the paper feeder 10. The image forming device 20 transports the roll paper P with the image formed thereon toward the winding device 30. The winding device 30 is a device that winds up the roll paper P transported from the image forming device 20 around a paper tube. In the winding device 30, for example, as shown in FIG. 1, the roll paper P is wound around the paper tube of a rotating shaft 31 and held in a roll shape. The winding device 30 rotates the roll paper P transported to the paper tube around the rotating shaft 31, and winds it up as a roll paper product P' around the rotating shaft 31 at a constant speed via multiple rollers (e.g., transport rollers, paper discharge rollers). Note that while this description explains an embodiment in which an image is formed (printed) on paper as a recording medium, this embodiment can also be applied to image forming devices that record on recording media other than paper.

[0012] Next, the configuration of the image forming apparatus will be described in detail using FIG. 2. FIG. 2 is a functional block diagram showing the configuration related to control of the image forming apparatus 20. In this diagram, the paper feeder 10 and the winding device 30 are depicted as external devices of the image forming apparatus. As shown in the diagram, the image forming apparatus 20 includes, for example, a paper transport unit 21, an image forming unit 22, a communication unit 23, a control unit 24, a memory unit 25, and an operation display unit 26. The paper transport unit 21 is a transport mechanism for roll paper P inside the image forming apparatus 20. For example, the paper transport unit 21 transports the roll paper P transported from the paper feeder 10 to the image forming unit 22 using multiple rollers, and then transports the roll paper P that has passed through the image forming unit 22 to the winding device 30. The image forming unit 22 forms an image on the roll paper P supplied from the paper feeder 10 based on print data for which an output command has been received. The image forming unit 22 transports the roll paper P with the image formed on it toward the winding device 30. The communication unit 23 is configured, for example, by a communication control card such as a LAN (Local Area Network) card. The communication unit 23 transmits and receives various data to and from external devices (e.g., personal computers) connected to a communication network such as a LAN or a WAN (Wide Area Network). The control unit 24 is configured, for example, by a CPU (Central Processing Unit) and RAM (Random Access Memory). The CPU of the control unit 24 reads various programs, such as system programs and processing programs, stored in the storage unit 25, loads them into the RAM, and executes various processes according to the loaded programs. For example, the control unit 24 can perform image formation processing to execute an image formation job (hereinafter referred to as a job) in response to a user's instruction. The image formation processing of the control unit 24 includes, for example, converting a received PDF job into an image of printer device-dependent colors (Cyan, Magenta, Yellow, and Black) using a printer profile. Furthermore, the image formation processing of the control unit 24 can assign specific device-independent color Lab values or device-dependent color CMYK values to spot color names included in the received PDF job. The user can specify specific Lab values or CMYK values via the operation display unit 26.It should be noted that the printer device dependent colors refer to colors that depend on the image forming device 20.

[0013] The storage unit 25 is configured by, for example, a non-volatile semiconductor memory (so-called flash memory) or an HDD (Hard Disk Drive). The storage unit 25 stores various programs, including system programs and processing programs, executed by the control unit 24, as well as various data required for executing these programs. Note that, although the image forming apparatus 20 in this embodiment functions as an information processing apparatus having the control unit 24, a separate information processing apparatus connected to the image forming apparatus 20 may also function as the control unit 24.

[0014] The operation display unit 26 includes a display unit 26a and an operation unit 26b, and is configured, for example, with a touch panel liquid crystal display (LCD). Various information is displayed on the display screen of the display unit 26a in accordance with display control signals input from the control unit 24. The operation unit 26b includes various operation keys, such as a numeric keypad and a start key, accepts various input operations by the user, and outputs operation signals to the control unit 24. The operation display unit 26 is used, for example, to set divider information when executing a job. The divider information is information on the insertion position of divider pages to be inserted in addition to the pages to be printed in the page information included in the job when the roll paper product P' needs to be sorted and delivered into multiple reels. The divider information is inserted in advance before executing the job. The divider information is generated by the user arbitrarily setting conditions such as the number of prints, number of copies, print length, print weight, and print diameter. The print weight is the weight of the product P'. The print diameter is the diameter of the product P'.

[0015] Next, we will explain the operation of the image forming apparatus 20 when forming an image on roll paper P. First, a user creates job data in an external device of the image forming system 1, configures print settings and the number of rolls to be delivered for the job, and transmits this information to the image forming apparatus 20 via a communications network. The control unit 24 of the image forming apparatus 20 receives the job data and a job ticket containing the job's print settings and the number of rolls to be delivered, transmitted from the external device, via the communications unit 23. The inspection unit 27 is a device that verifies whether an image is printed on roll paper without any ejection defects. The inspection unit 27 prints an ejection defect inspection pattern on a sheet, scans the printed pattern with a scanner, and verifies whether the scanned image has deteriorated in image quality. If the inspection unit 27 detects deterioration in image quality, it determines that a nozzle ejection defect has occurred and stops the image forming apparatus 20. The inspection unit 27 has a colorimetric function and measures the image based on the device color patch data printed by the image forming apparatus 20 to obtain colorimetric values (Lab). The image obtained by the image forming apparatus 20 printing based on patch data using device colors will be described in detail later (see layout 501 in FIG. 5).

[0016] FIG. 3 shows a GUI screen for spot color correction. Each GUI screen shown in FIG. 3 is displayed on the display unit 26a of the operation / display unit 26. GUI screen 301 is a screen for selecting whether to perform automatic color adjustment or manual color adjustment for spot color correction. When automatic color adjustment is selected on GUI screen 301 and the proceed button is pressed, GUI screen 302 is displayed. The user inputs the L, a, and b values (referred to as Lab values) of the target color via GUI screen 302, and also inputs the ΔL, Δa, and Δb values (referred to as ΔLab values) for determining surrounding colors for the target color. The operation / display unit 26 and the control unit 24 accept such inputs by the user. Details of the target color and surrounding colors will be described later with reference to FIG. 4. When manual color adjustment is selected via GUI screen 301 and the proceed button is pressed, GUI screen 303 is displayed. The user inputs the C, M, Y, and K values via GUI screen 303. The operation / display unit 26 and the control unit 24 accept such inputs by the user. The timings for displaying the GUI screens 301, 302, and 303 will be described in detail below with reference to FIG.

[0017] FIG. 4 shows a group of lattice points 400 representing the relationship between a target color and surrounding colors. The central lattice point 401 represents the L, a, and b of the target color. This central lattice point 401 is referred to as the target color lattice point. The 26 surrounding lattice points, whose positions are shifted within a predetermined range from the lattice point 401 corresponding to the target color, correspond to the surrounding colors. The positional shift for each of the 26 lattice points is assumed to be −ΔL, 0, or +ΔL in the L direction, −Δa, 0, or +Δa in the a direction, and −Δb, 0, or +Δb in the b direction. These 26 lattice points are referred to as surrounding color lattice points. Details of the 27 lattice points corresponding to the target color and surrounding colors will be described later with reference to FIG. 5. Values for L, a, and b, as well as ΔL, Δa, and Δb, are entered via the GUI screen 302 shown in FIG. 3.

[0018] 5 is a diagram showing patch data of device colors. A layout 501 is a layout in which patch images 502, which are images based on the patch data of device colors, are arranged on a sheet of paper. This layout 501 is obtained by printing on a sheet of paper based on the patch data of device colors using the image forming unit 22. In this embodiment, 27 patch images 502 are arranged in the layout 501, as indicated by ID1 to ID27 in the figure.

[0019] Table 504 is a table for storing color information corresponding to each of the 27 patch images arranged in layout 501. For example, ID14 corresponds to the target color, and the record for ID14 in table 504 describes the L, a, and b values input or received via GUI screen 302. As described above, the target color corresponding to ID14 corresponds to the central lattice point 401 in FIG. 4. In contrast, IDs 1 to 13 and IDs 15 to 27 correspond to peripheral colors. For example, referring to the record for ID26 in table 504, values based on the L, a, and b values input or received via GUI screen 302 and the ΔL, Δa, and Δb values input or received via GUI screen 302 are described. Specifically, L+ΔL is described as the L value, a+Δa is described as the a value, and b is described as the b value.

[0020] A patch image 503 indicates the specific content to be actually printed for one (ID27) of the 27 patch images 502 arranged in the layout 501. For each of the 27 patch images, as in the patch image 503, values of printer-device-dependent colors (cyan, magenta, yellow, and black) and an image filled with the printer-device-dependent colors specified by the values are printed. The combination of the values of cyan, magenta, yellow, and black is referred to as a CMYK value. The inspection unit 27 measures the color of the image filled with the printer-device-dependent colors to obtain Lab values corresponding to each of ID1 to ID27.

[0021] 6 is a flowchart of the spot color correction (color matching) process, which is a series of processes including a step of accepting a selection of automatic or manual adjustment before printing the spot color correction patch. Note that, hereinafter, S represents a process (step) in the series of flows.

[0022] In S601, the control unit 24 displays a GUI screen for receiving a selection input of automatic adjustment or manual adjustment on the display unit 26a of the operation display unit 26. A GUI screen 301 shown in Fig. 3 is an example of the GUI screen displayed in this step.

[0023] In S602, the control unit 24 accepts a selection input of automatic adjustment or manual adjustment, which is a user input via the GUI screen displayed in S601.

[0024] In S603, the control unit 24 determines whether the selection input received in S602 indicates automatic adjustment. If the determination result in this step is true, the process proceeds to S604. On the other hand, if the determination result in this step is false, the process proceeds to S613.

[0025] In S604, the control unit 24 displays, on the display unit 26a of the operation display unit 26, an input GUI screen for inputting the name of the spot color to be adjusted.

[0026] In S605, the control unit 24 accepts the input of the spot color name specified via the GUI screen displayed in S604.

[0027] In S606, the control unit 24 displays an input GUI screen for inputting the Lab values and ΔLab values of the spot color on the display unit 26a of the operation display unit 26. The GUI screen 302 shown in Fig. 3 is an example of the GUI screen displayed in this step.

[0028] In S607, the control unit 24 accepts input of the Lab values and ΔLab values specified via the GUI screen displayed in S606.

[0029] In S608, the control unit 24 generates image data for a layout in which a plurality of patch images are arranged, each of which consists of a text portion with CMYK values of printer device-dependent colors and an image portion filled with a single color, based on the Lab values and ΔLab values received in S607. Specifically, the control unit 24 generates image data for the patch images by calculating the CMYK values of the device-dependent colors based on the Lab values and ΔLab values using the printer profile. In the example of FIG. 5, the image data for the patch images is generated by calculating the CMYK values of the device-dependent colors based on the combinations of L values, a values, and b values (stored in table 504) corresponding to ID1 to ID27, respectively, using the printer profile. The image data for layout 501 shown in FIG. 5 is an example of layout image data generated in this step.

[0030] In S609, the control unit 24 prints a plurality of patch images on a paper surface based on the image data of the layout generated in S608, using the image forming unit 22. In the example of Fig. 5, 27 patch images 502 are printed.

[0031] In S610, the control unit 24 acquires the colorimetric values (Lab values) of each patch image by measuring the color of the filled-in image included in each of the multiple patch images printed in S609. In the example of Fig. 5, the inspection unit 27 measures the color of the patch images ID1 to ID27 to acquire the colorimetric values (Lab values) for each of ID1 to ID27.

[0032] In S611, the control unit 24 calculates the color difference between the Lab value of the target color received in S607 and the Lab value of each patch image acquired by the colorimetry in S610, and determines the patch image (ID) corresponding to the smallest color difference among the calculated color differences. Note that CIEDE2000 may be used in calculating the color difference.

[0033] In S612, the control unit 24 sets the CMYK value of the device-dependent color corresponding to the ID determined in S611 as the correction value of the spot color having the spot color name received in S605, that is, stores the CMYK value in the memory unit 25 as the correction value.

[0034] In S613, the control unit 24 displays, on the display unit 26a of the operation display unit 26, an input GUI screen for inputting the name of the spot color to be adjusted.

[0035] In S614, the control unit 24 accepts the input of the spot color name specified via the GUI screen displayed in S613.

[0036] In S615, the control unit 24 displays an input GUI screen for inputting the CMYK values after spot color correction on the display unit 26a of the operation display unit 26. The GUI screen 303 shown in Fig. 3 is an example of the GUI screen displayed in this step.

[0037] In S616, the control unit 24 accepts the input of the CMYK values specified via the GUI screen displayed in S615.

[0038] In S617, the control unit 24 sets the CMYK values received in S616 as correction values for the spot color having the spot color name received in S614, that is, stores the CMYK values in the storage unit 25 as the correction values.

[0039] FIG. 7 is a flowchart of the spot color correction (color matching) process, and is a flowchart of a series of processes including a step of accepting a selection of automatic adjustment or manual adjustment after printing a patch for spot color correction.

[0040] In S701, the control unit 24 displays, on the display unit 26a of the operation display unit 26, an input GUI screen for inputting the name of a spot color to be adjusted.

[0041] In S702, the control unit 24 accepts the input of the spot color name specified via the GUI screen displayed in S701.

[0042] In S703, the control unit 24 displays, on the display unit 26a of the operation display unit 26, an input GUI screen for inputting the Lab values and ΔLab values of the spot colors.

[0043] In S704, the control unit 24 accepts input of the Lab values and ΔLab values specified via the GUI screen displayed in S703.

[0044] In S705, the control unit 24 generates image data of a layout in which a plurality of patch images, each consisting of a character portion of the printer device-dependent color CMYK value and an image portion filled with a single color, are arranged, based on the Lab values and ΔLab values received in S704. Note that this step is the same as S608 in FIG. 6.

[0045] In S706, the control unit 24 uses the image forming unit 22 to print a plurality of patch images on paper based on the image data of the layout generated in S705.

[0046] In S707, the control unit 24 acquires the colorimetric values (Lab values) of each patch image by measuring the color of each of the patch images printed in S706. This step is the same as S610 in FIG. 6.

[0047] In S708, the control unit 24 calculates the color difference between the Lab value of the target color received in S704 and the Lab value of each patch image acquired by the colorimetry in S707, and determines the patch image (ID) corresponding to the smallest color difference among the calculated color differences. Note that CIEDE2000 may be used in calculating the color difference.

[0048] In S709, the control unit 24 accepts a selection input as to whether or not to use the CMYK values entered by the user based on the CMYK values of the printed patch image and the printer device dependent colors, rather than using the CMYK values of the patch image determined in S708.

[0049] In S710, the control unit 24 determines whether a selection to use CMYK values input by the user based on the CMYK values of the printed patch image and the printer device-dependent colors, rather than using the CMYK values of the patch image determined in S708, was accepted in S709. If the determination result in this step is true, the process proceeds to S712. On the other hand, if the determination result in this step is false, the process proceeds to S711.

[0050] In S711, the control unit 24 sets the CMYK value of the device-dependent color corresponding to the ID determined in S708 as the correction value of the spot color having the spot color name received in S702, that is, stores the CMYK value in the memory unit 25 as the correction value.

[0051] In S712, the control unit 24 displays, on the display unit 26a of the operation display unit 26, an input GUI screen for inputting the CMYK values of the printer device dependent colors.

[0052] In S713, the control unit 24 accepts the input of the CMYK values of the printer device dependent colors designated via the GUI screen displayed in S712.

[0053] In S714, the control unit 24 sets the CMYK values received in S713 as correction values for the spot color of the spot color name received in S702, that is, stores the CMYK values in the storage unit 25 as the correction values.

[0054] <Effects of this embodiment> In this embodiment, during automatic adjustment, Lab values and ΔLab values input by the user are accepted, and a layout is printed in which multiple patch images are arranged, each consisting of a text portion of CMYK values of a printer device-dependent color and an image portion filled with a single color. Then, the CMYK values (device-dependent colors) corresponding to the patch image with the smallest color difference are set as the correction value for the spot color of the spot color name. Meanwhile, during manual adjustment, the above layout is printed in the same way as during automatic adjustment, but the user is prompted to select a desired patch image from the printed patch images, and the CMYK values corresponding to the selected patch image are set as the correction value for the spot color of the spot color name. This configuration enables highly accurate spot color correction.

[0055] [Second embodiment] In this embodiment, the user is asked whether or not to re-execute spot color correction under predetermined conditions.

[0056] FIG. 8 is a flowchart of the spot color correction (color matching) process, and is a flowchart of a series of processes including a step of confirming with the user whether or not to re-execute the spot color correction under predetermined conditions.

[0057] In S801, the control unit 24 displays a GUI screen for receiving a selection input of automatic adjustment or manual adjustment on the display unit 26a of the operation display unit 26. A GUI screen 301 shown in Fig. 3 is an example of the GUI screen displayed in this step.

[0058] In S802, the control unit 24 accepts a selection input of automatic adjustment or manual adjustment, which is a user input via the GUI screen displayed in S801.

[0059] In S803, the control unit 24 determines whether the selection input received in S802 indicates automatic adjustment. If the determination result in this step is true, the process proceeds to S804. On the other hand, if the determination result in this step is false, the process proceeds to S816.

[0060] In S804, the control unit 24 displays, on the display unit 26a of the operation display unit 26, an input GUI screen for inputting the name of the spot color to be adjusted.

[0061] In S805, the control unit 24 accepts the input of the spot color name specified via the GUI screen displayed in S804.

[0062] In S806, the control unit 24 displays an input GUI screen for inputting the Lab values and ΔLab values of the spot color on the display unit 26a of the operation display unit 26. The GUI screen 302 shown in Fig. 3 is an example of the GUI screen displayed in this step.

[0063] In S807, the control unit 24 accepts input of the Lab values and ΔLab values specified via the GUI screen displayed in S806.

[0064] In S808, the control unit 24 generates image data of a layout in which a plurality of patch images are arranged, each of which is composed of a text portion of CMYK values of printer device-dependent colors and an image portion filled with a single color, based on the Lab values and ΔLab values received in S807. Specifically, the control unit 24 generates image data of the patch images by calculating the CMYK values of the device-dependent colors based on the Lab values and ΔLab values using a printer profile. In the example of FIG. 5, the image data of the patch images is generated by calculating the CMYK values of the device-dependent colors based on the combinations of L values, a values, and b values (stored in table 504) corresponding to ID1 to ID27, respectively, using the printer profile. The image data of layout 501 shown in FIG. 5 is an example of layout image data generated in this step.

[0065] In S809, the control unit 24 prints a plurality of patch images on a paper surface based on the image data of the layout generated in S808, using the image forming unit 22. In the example of Fig. 5, 27 patch images are printed.

[0066] In S810, the control unit 24 acquires the colorimetric values (Lab values) of each patch image by measuring the color of the filled-in image included in each of the multiple patch images printed in S809. In the example of Fig. 5, the inspection unit 27 measures the color of the patch images ID1 to ID27 to acquire the colorimetric values (Lab values) for each of ID1 to ID27.

[0067] In S811, the control unit 24 calculates the color difference between the Lab value of the target color received in S807 and the Lab value of each patch image acquired by the colorimetry in S810, and determines the patch image (ID) corresponding to the smallest color difference among the calculated color differences. Note that CIEDE2000 may be used in calculating the color difference.

[0068] In S812, the control unit 24 determines whether the colorimetric values (Lab values) of the patch image determined in S811 fit within the range of a three-dimensional shape defined by surrounding pixels obtained by adding / subtracting the ΔLab value received in S807 to / from the Lab values received in S807. Specifically, as shown in the example of FIG. 4, the control unit 24 determines whether the colorimetric values (Lab values) of the ID determined in S811 fit within the range of a rectangular parallelepiped defined by a group of grid points consisting of the target color grid point and 26 surrounding color grid points. If the determination result in this step is true, the process proceeds to S815. On the other hand, if the determination result in this step is false, the process proceeds to S813.

[0069] In S813, the control unit 24 displays a GUI screen on the display unit 26a of the operation display unit 26 for accepting a selection input of whether or not to re-execute the automatic adjustment, and accepts the selection input of whether or not to re-execute the automatic adjustment, which is a user input via the displayed GUI screen.

[0070] In S814, the control unit 24 determines whether re-execution of the automatic adjustment has been selected via the GUI screen displayed in S813. If the determination result in this step is true, the process proceeds to S806. On the other hand, if the determination result in this step is false, the process proceeds to S815.

[0071] In S815, the control unit 24 sets the CMYK value of the device-dependent color corresponding to the ID determined in the most recent S811 as the correction value of the spot color of the spot color name received in S805, that is, stores the CMYK value in the memory unit 25 as the correction value.

[0072] In S816, the control unit 24 displays, on the display unit 26a of the operation display unit 26, an input GUI screen for inputting the name of the spot color to be adjusted.

[0073] In S817, the control unit 24 accepts the input of the spot color name specified via the GUI screen displayed in S816.

[0074] In S818, the control unit 24 displays an input GUI screen for inputting the CMYK values after spot color correction on the display unit 26a of the operation display unit 26. The GUI screen 303 shown in Fig. 3 is an example of the GUI screen displayed in this step.

[0075] In S819, the control unit 24 accepts the input of the CMYK values specified via the GUI screen displayed in S818.

[0076] In S820, the control unit 24 sets the CMYK values received in S819 as the correction values of the spot color having the spot color name received in S817, that is, stores the CMYK values in the storage unit 25 as the correction values.

[0077] 9A and 9B show examples of GUI screens that present the results of spot color correction to the user. These GUI screens are displayed on the display unit 26a of the operation display unit 26. FIG. 9A shows an example of a GUI screen that presents only the results of the automatic adjustment to the user without including a message asking whether or not to re-execute the spot color correction, that is, a screen that is displayed when the determination in S812 is YES. On the other hand, FIG. 9B shows an example of a GUI screen that includes the results of the automatic adjustment as well as a message asking whether or not to re-execute the spot color correction, that is, a GUI screen that is displayed when the determination in S812 is NO, and is displayed at the timing of S813.

[0078] <Effects of this embodiment> In this embodiment, a GUI screen is displayed to the user to confirm whether or not to re-execute spot color correction under predetermined conditions, and the user can re-execute spot color correction after viewing the GUI screen as needed. This prevents the correction values after spot color correction from deviating significantly from the target values.

[0079] [Other embodiments] The present disclosure can also be realized by supplying a program that realizes one or more functions of the above-described embodiments to a system or device via a network or a storage medium, and having one or more processors in the computer of the system or device read and execute the program. It can also be realized by a circuit (e.g., ASIC) that realizes one or more functions.

[0080] [Technical Features of the Present Disclosure] The present disclosure includes the following configurations.

[0081] (Configuration 1) An image forming apparatus comprising: a receiving means for receiving a first Lab value and a ΔLab value of a target color; a generating means for generating image data of a layout in which a plurality of patch images are arranged based on the first Lab value and the ΔLab value using a printer profile, wherein the plurality of patch images each include an image portion filled with a single color; a forming means for forming the plurality of patch images on a recording medium based on the image data of the layout; an acquiring means for measuring the image portion of each of the plurality of patch images formed by the forming means and acquiring a second Lab value for each of the plurality of patch images; a determining means for determining, from the plurality of patch images, a patch image whose second Lab value is closest to the first Lab value of the target color; and a setting means for setting the CMYK value of the patch image determined by the determining means as a correction value for a spot color. (Configuration 2) Each of the plurality of patch images further includes a character portion in which CMYK values of device-dependent colors are described, and the CMYK values set as the correction values by the setting means are the CMYK values described in the character portion of the patch image determined by the determination means. 2. The image forming apparatus according to claim 1, (Configuration 3) The image forming apparatus according to configuration 1 or 2, wherein each of the plurality of patch images corresponds to either the target color or a peripheral color of the target color. (Configuration 4) An image forming apparatus according to any one of configurations 1 to 3, comprising a display means for displaying a GUI screen and a display control means for displaying the GUI screen on the display means, wherein the display control means displays a first GUI screen on the display means that allows a user to select whether to perform automatic or manual adjustment of spot colors. (Configuration 5) The image forming apparatus according to any one of configurations 1 to 4, wherein the display control means displays a second GUI screen on the display means, in which the user inputs the name of the spot color to be adjusted. (Configuration 6) An image forming apparatus described in any one of configurations 1 to 5, further comprising a judgment means for judging whether the colorimetric value of the patch image determined by the determination means falls within the range of a rectangular parallelepiped defined by a group of lattice points between the target color and the surrounding colors, and if the judgment means judges that the colorimetric value does not fall within the range, the display control means displays a third GUI screen on the display means, which allows the user to select whether or not to re-execute automatic adjustment of the spot color. (Configuration 7) An image forming apparatus according to any one of configurations 1 to 6, characterized in that the group of grid points includes a target color grid point corresponding to the target color and a surrounding color grid point corresponding to the surrounding colors, the number of the target color grid points being 1, and the number of the surrounding color grid points being 26. (Configuration 8) An image forming apparatus according to any one of configurations 1 to 7, characterized in that when re-execution of automatic spot color adjustment is selected via the third GUI screen, automatic spot color adjustment is re-executed. (Method for controlling an image forming apparatus) a generating step of generating image data of a layout in which a plurality of patch images are arranged based on the first Lab value and the ΔLab value using a printer profile, wherein each of the plurality of patch images includes an image portion filled with a single color; a forming step of forming the plurality of patch images on a recording medium based on the image data of the layout; an acquiring step of measuring the color of the image portion of each of the plurality of patch images formed in the forming step and acquiring a second Lab value for each of the plurality of patch images; a determining step of determining, from the plurality of patch images, a patch image whose second Lab value is closest to the first Lab value of the target color; and a setting step of setting the CMYK values of the patch image determined in the determining step as correction values for a spot color. (program) a generating step of generating image data of a layout in which a plurality of patch images are arranged based on the first Lab value and the ΔLab value using a printer profile, wherein each of the plurality of patch images includes an image portion filled with a single color; a forming step of forming the plurality of patch images on a recording medium based on the image data of the layout; an acquiring step of measuring the color of the image portion of each of the plurality of patch images formed in the forming step and acquiring a second Lab value for each of the plurality of patch images; a determining step of determining, from the plurality of patch images, a patch image whose second Lab value is closest to the first Lab value of the target color; and a setting step of setting the CMYK values of the patch image determined in the determining step as spot color correction values. [Explanation of symbols]

[0082] 20 Image forming device 22 Image forming unit 24 Control Unit

Claims

1. a receiving means for receiving a first Lab value and a ΔLab value of the target color; a generating means for generating image data of a layout in which a plurality of patch images are arranged based on the first Lab value and the ΔLab value by using a printer profile, the generating means including an image portion filled with a single color; a forming means for forming the plurality of patch images on a recording medium based on the image data of the layout; an acquisition unit that measures the color of the image portion of each of the plurality of patch images formed by the formation unit and acquires a second Lab value for each of the plurality of patch images; a determining means for determining, from among the plurality of patch images, a patch image whose second Lab value is closest to the first Lab value of the target color; a setting unit that sets the CMYK values of the patch image determined by the determining unit as correction values for the spot colors; An image forming apparatus comprising:

2. each of the plurality of patch images further includes a character portion in which CMYK values of device-dependent colors are described; the CMYK values set as the correction values by the setting unit are CMYK values written in the character portion of the patch image determined by the determining unit; 2. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

3. each of the plurality of patch images corresponds to either the target color or a peripheral color of the target color; 3. The image forming apparatus according to claim 1, wherein the image forming apparatus is a recording medium.

4. a display means for displaying a GUI screen; a display control means for displaying the GUI screen on the display means; and the display control means displays on the display means a first GUI screen that allows a user to select whether to perform automatic adjustment or manual adjustment of the spot color.

4. The image forming apparatus according to claim 3, wherein the image forming apparatus is a recording medium.

5. the display control means displays on the display means a second GUI screen for a user to input the name of a spot color to be adjusted.

5. The image forming apparatus according to claim 4.

6. The method further includes a determination unit that determines whether or not the colorimetric values of the patch image determined by the determination unit are within a rectangular parallelepiped defined by a group of grid points of the target color and the surrounding colors, When the determining means determines that the difference does not fall within the specified range, the display control means displays on the display means a third GUI screen that allows the user to select whether or not to re-execute the automatic spot color adjustment.

6. The image forming apparatus according to claim 5,

7. the group of grid points includes a target color grid point corresponding to the target color and a surrounding color grid point corresponding to the surrounding colors, The number of the target color grid points is 1, and the number of the surrounding color grid points is 26.

7. The image forming apparatus according to claim 6, wherein the image forming apparatus is a recording medium.

8. When re-execution of automatic spot color adjustment is selected via the third GUI screen, automatic spot color adjustment is re-executed.

8. The image forming apparatus according to claim 7,

9. a receiving step of receiving a first Lab value and a ΔLab value of the target color; a generating step of generating image data of a layout in which a plurality of patch images are arranged based on the first Lab value and the ΔLab value using a printer profile, the generating step including: a forming step of forming the plurality of patch images on a recording medium based on the image data of the layout; an acquisition step of colorimetrically measuring the image portion of each of the plurality of patch images formed in the formation step to acquire second Lab values for each of the plurality of patch images; a determining step of determining, from the plurality of patch images, a patch image whose second Lab value is closest to the first Lab value of the target color; a setting step of setting the CMYK values of the patch image determined in the determination step as correction values of the spot color; 1. A method for controlling an image forming apparatus, comprising:

10. A program for causing a computer to execute the method according to claim 9.

Images