JP2015133679A - Image forming apparatus, image forming system, and image forming method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To show a client side to what degree the hue of a print is improved after calibration in comparison with before the calibration.SOLUTION: An image forming apparatus 6 of the present invention acquires calibration data for approximate the grayscale of an image formed on a sheet to a target grayscale as first calibration data, and stores calibration data used in grayscale correction processing before the acquisition of the first calibration data in a calibration data storage section 42A as second calibration data. An output section 56 outputs a first grayscale evaluation image having the grayscale thereof corrected by a grayscale processing section 44 according to the first calibration data, and a second grayscale evaluation image reproducing the grayscale before the calibration processing according to the second calibration data which are printed on the same sheet.

Description

  The present invention relates to an image forming apparatus, an image forming system including the image forming apparatus, and an image forming method.

  In recent years, in order to reduce the delivery cost of proofed printed materials in the printed material production process, the network system is used to send proof data to the client-side color printer by remote control, and the client-side printer. There is a growing need to output proofs directly. In order to satisfy this need, it is necessary to calibrate each parameter applied to the output gamma correction processing (tone correction) for the printer on the client side so that the printed matter is always stably output. In calibration, a test pattern (gradation patch) is built in the printer, the gradation patch is output, and the output image is read by the scanner and compared with the test pattern. The parameters are calibrated and the color tone of the output image is adjusted.

  Conventionally, there has been proposed a printing system that performs calibration by causing an output gradation patch to be read by a printer body and feeding back the read data to the printing system (see, for example, Patent Documents 1 and 2). Furthermore, a printing system has been proposed in which calibration is performed automatically by remotely controlling a client-side printer at a remote location. For example, in Patent Document 3, the job data to be transmitted has calibration execution information, and the remote front-end server itself that receives the job data controls the printer to calibrate the printing system. A printing system is described that controls to perform calibration only for specified specific job data. In the printing system described in Patent Document 3, it is possible to return the calibration data to the state before the setting change after the calibration, or to switch the job data after the setting to be further calibrated. is there.

  However, in the conventional print system, only the presence / absence of calibration is presented to the client, so that the SE on the client side or the client itself can actually print with the color desired by the calibration. In addition, there is a problem that it is not possible to clearly determine whether or not the color tone of the printed matter has improved compared to before the calibration.

  The present invention has been made in view of the above, and an object of the present invention is to provide an easy-to-understand indication on the client side how much the color of a printed product after calibration has improved compared to before calibration.

  In order to solve the above-described problems and achieve the object, the present invention provides gradation correction processing means for performing gradation correction processing on input image data using gradation correction data, and the gradation correction. Output means for forming an image of data on which gradation correction processing has been performed by the processing means on a medium and outputting the medium; and a target in which the gradation of the image formed on the medium is in line with a target color A calibration unit that executes a calibration process for calibrating the gradation correction data used by the gradation correction processing unit so as to obtain a gradation; and a gradation evaluation image on the medium after the calibration process by the calibration unit. And a storage means for storing data required for the gradation correction processing, wherein the calibration means is based on density conversion data of gradation patch read data formed on the medium. Formed on the medium Gradation correction data for approximating the gradation of an image to be a target gradation is acquired as first gradation correction data, and the gradation correction processing is performed before acquiring the first gradation correction data. The used gradation correction data is stored in the storage means as second gradation correction data, and the control means uses the first gradation correction data for the gradation processing means to the output means. The first gradation evaluation image whose gradation is corrected in this way and the second gradation evaluation image in which the gradation before the calibration process is reproduced using the second gradation correction data are the same. It is characterized by being formed on a medium.

  According to the present invention, there is an effect that it is possible to present to the client side in an easy-to-understand manner how much the color of the printed matter after the calibration process has improved compared to before the calibration.

FIG. 1 is a block diagram showing a configuration of an example of an image forming system according to an embodiment of the present invention. FIG. 2 is a block diagram showing a configuration of the image forming apparatus shown in FIG. FIG. 3 is a flowchart showing a processing procedure of proof printing output processing in the image forming system shown in FIG. FIG. 4 is a flowchart showing a processing procedure of the job data transmission process shown in FIG. FIG. 5 is a flowchart showing a processing procedure of the patch data output process shown in FIG. FIG. 6 is a flowchart showing a processing procedure of the calibration data generation processing of FIG. FIG. 7 is a flowchart showing a processing procedure of the job data output process shown in FIG. FIG. 8 is a diagram illustrating an example of a printing surface of a sheet output from the output unit illustrated in FIG. FIG. 9 is a flowchart showing a processing procedure of the gradation correction data transmission / reception processing shown in FIG. FIG. 10 is a flowchart showing another processing procedure of the job data output process shown in FIG. FIG. 11 is a diagram illustrating an example of a printing surface of a sheet output from the output unit illustrated in FIG. FIG. 12 is a diagram illustrating an example of a printing surface of a sheet output from the output unit illustrated in FIG. FIG. 13 is a flowchart showing another processing procedure of the job data output process shown in FIG. FIG. 14 is a diagram illustrating a configuration of an example of an image forming apparatus applicable to the embodiment.

  Embodiments of an image forming system according to the present embodiment will be described below in detail with reference to the accompanying drawings.

(Embodiment)
FIG. 1 is a block diagram showing a configuration of an example of an image forming system according to an embodiment of the present invention. As shown in FIG. 1, the image forming system 1 according to the embodiment has a configuration in which a site A1, a site A2, and a site B are connected to each other via a network N so as to communicate with each other. Sites A1 and A2 are client-side sites. Site B is the calibration data design side.

  On the client side, the site A1 is a site on the remote transmission side. The site A1 is provided with a terminal device 2 operated by an SE or a client and a front-end server 3 connected to the network N. The terminal device 2 and the front-end server 3 are communicably connected. Site A2 is a site on the remote receiving side. The site A2 is provided with a front-end server 4 that is connected to the network N and functions as a printer controller, a printer engine 5 that is a color printer, and a terminal device 7 that is operated by a client. The front-end server 4 and the printer engine 5 and the terminal device 7 are communicably connected. The front end server 4 and the printer engine 5 constitute an image forming apparatus 6 that forms an image on a medium such as paper and outputs the medium. The printer engine 5 is an output device that can form a color image using cyan (C), magenta (M), yellow (Y), and black (K) color materials by electrophotography. The output method of the printer engine 5 is not limited to the electrophotographic method, and other methods such as an ink jet method may be adopted.

  The site B is provided with a front-end server 8 connected to the network N and a terminal device 9 operated by a designer of calibration data, and the front-end server 8 and the terminal device 9 are connected to be communicable. The terminal devices 2, 7, and 9 have a communication function that enables network communication together with a CPU and input / output devices that enable various processes such as monitor display and image processing.

  In the image forming system 1, proofs can be directly output from the client-side printer engine 5 via the network N for printed matter created by the designer in response to an order from the client. Specifically, data is transmitted from the terminal device 2 of the remote transmission site A2 to the printer engine 5 of the remote reception site A2 by remote control, and the proof is output from the printer engine 5. Let

  The image forming apparatus 6 performs an output gamma correction process (gradation correction) for deriving a gradation correction value so as to obtain an optimum density / gradation property on the input image data, and then paper or the like. An image is formed on the medium, and the medium (printed material) on which the image is formed is output. In the gradation correction processing, gradation correction is performed on input image data using a preset conversion equation. Each parameter used in the gradation correction processing is set in gradation correction data in the calibration data in the CMYK one-dimensional lookup table format. The calibration data is set in a calibration table held by the image forming apparatus 6. The calibration data is set based on information on engine characteristics, characteristics of actual machines, reference data (parameters) designed in advance, and the like. Here, the image forming apparatus 6 is subjected to a calibration process for calibrating the density variation so that the printed matter is output from the printer engine 5 with a color according to the client's request. The calibration process is a process for optimizing each parameter of the gradation correction data of the calibration data in order to bring the color of the output image closer to the color desired by the client. As parameters required for the calibration data, there are numerical values of CMYK density data obtained by color-separating and reading the actually output patch into RGB colors. In the calibration process, each numerical value of the CMYK density data is given as a coefficient to a predetermined conversion formula, and is actually output on the actual machine based on the target gradation according to the target color desired by the SE or the client. Calibration data is optimized by obtaining a gradation curve that can convert the input data so that the gradation of the image to be approximated to the target gradation.

  In the image forming system 1, calibration processing for the image forming apparatus 6 at the site A 2 is performed by remote control via the network N. First, a calibration execution instruction Sc is transmitted from the terminal device 2 operated by the SE or client at the site A1 to the front-end server 4 at the site A2. The execution instruction Sc is transmitted to the front end server 4 of the site A2 via the front end server 3 and the network N. Of course, the terminal device 7 connected to the front-end server 4 can also directly instruct execution of calibration. The image forming apparatus 6 at the site A2 on the remote receiving side performs calibration processing in accordance with the execution instruction Sc, and acquires optimized calibration data. Then, the image forming apparatus 6 causes the print engine 5 to output a printed matter on which a gradation evaluation image for evaluating the calibration processing result is formed.

  At this time, from an output unit 56 of the printer engine 5 described later, a gradation evaluation image (first image) in which gradation correction has been performed using newly optimized calibration data (first calibration data). Gradation evaluation image), and the gradation evaluation image (second calibration data) in which the gradation before the calibration processing is reproduced using the calibration data (second calibration data) used before the calibration. Are also printed on the same paper. Further, the third and fourth gradation evaluation images having gradation values near the gradation of the first evaluation image are also printed on this sheet. As described above, in the present embodiment, since the gradation evaluation image before the calibration process after the calibration process is also printed on the same sheet, how the color changes before and after the calibration process is determined. Or present it to the client in an easy-to-understand manner. By checking this paper, whether the client side SE or the client itself can actually print with the desired color by calibration, and the color of the printed product is the same as before the calibration. It is possible to clearly determine how much the improvement has been made.

  If the SE or the client recognizes that there is a problem in the printed gradation evaluation image, the information on the color desired for the image printed on the paper is input to the terminal devices 2 and 7. The desired color information includes, for example, specific visual desires and information indicating numerical values such as color space values. Accordingly, the request information Sd including the target color information required for the image printed on the sheet is calibrated from the terminal device 2 or the terminal device 7 via the front-end servers 3 and 4 and the network N. Sent to site B on the data design side. In the site B, when the front-end server 8 receives the request information Sd and the terminal device 9 is notified of the request information Sd, the designer operates the terminal device 9 to change the color according to the client's desire. In order to output an image, each parameter used for the gradation correction process is optimized and gradation correction data including each optimized parameter is created. This gradation correction data is transmitted as recommended gradation correction data Se from the terminal device 9 to the front end servers 3 and 4 via the front end server 8 and the network N, and stored in the storage unit of the front end servers 3 and 4. Stored. In the image forming system 1, the above is repeated by trial and error so that an image closer to the client's desire can be provided.

  Next, the image forming apparatus 6 constituted by the front end server 4 and the printer engine 5 will be described. FIG. 2 is a block diagram showing the configuration of the image forming apparatus 6 shown in FIG.

  As shown in FIG. 2, the front-end server 4 constituting the image forming apparatus 6 includes a network I / F unit 40, a job control unit 41 (control means), a job management unit 41A, a job analysis unit 41B, calibration data. Generating unit 42 (calibration means), calibration data storage unit 42A, communication I / F unit 43, rendering unit 44, gradation correction processing unit 45, gradation characteristic data storage unit 45A, calibration table 45B, patch data 46, An evaluation data storage unit 47 and a read data storage unit 48 are provided.

  The network I / F unit 40 is connected to the terminal device 7 shown in FIG. 1 and is connected to the network N connected to the front-end server 3 and the front-end server 8 on the calibration data design side to exchange information. The network I / F unit 40 receives a calibration execution command Sc transmitted from the terminal device 2 via the network N.

  The job control unit 41 controls the processing operation of each component of the image forming apparatus 6 based on the job data sent from the terminal devices 2 and 7. Note that job data refers to print job data when, for example, A4 data is printed. When N in 1 printing is instructed, print data for N sheets is obtained. The job management unit 41A performs management such as holding a job. Note that the process for holding a job is a process for holding a job without performing a printing process. When the job management unit 41A releases the hold, the printing process for this job is advanced. The job analysis unit 41B analyzes job ticket data included in job data. The job ticket data includes items for instructing the contents of processing, printing paper size setting information in the job, calibration setting information for setting whether or not to execute calibration processing, input from SE or client Information on the color of the target (desired) that has been set, and information that sets data for gradation evaluation for proof printing.

  The calibration data generation unit 42 calibrates the gradation correction data used by the gradation correction processing unit 45 described later so that the gradation of the image formed on the medium becomes a target gradation according to the target color. Perform the calibration process. The calibration data generation unit 42 is formed on the medium based on the density conversion data of the gradation patch read data and target gradation characteristic data stored in a gradation characteristic data storage unit 45A described later. In order to approximate the gradation of the image to the target gradation, calibration data in which each parameter of the gradation correction data is optimized is generated. The calibration data storage unit 42A stores the calibration data generated by the calibration data generation unit 42.

  The communication I / F unit 43 is connected to the printer engine 5 and exchanges data with the printer engine 5. The rendering unit 44 converts the image data in the patch data storage unit 46 and the evaluation data storage unit 47 into a bitmap image.

  The gradation correction processing unit 45 performs gradation correction processing on the input image data using predetermined gradation correction data. The gradation correction processing unit 45 performs gradation correction processing by applying gradation correction data included in calibration data set in a calibration table 45B described later.

  The gradation characteristic data storage unit 45A stores target gradation characteristic data and a plurality of calibration data including gradation correction data created on the calibration data design side. The target gradation characteristic data indicates an index of density (gradation) corresponding to the target color of the printed matter to be output. The calibration data generation unit 42 selects a target gradation according to a target color received by the operation unit 51 described later by referring to the target gradation characteristic data stored in the gradation characteristic data storage unit 45A. To do.

  The calibration data table 45B is a table in which calibration data including gradation correction data actually applied in the gradation correction processing is set. In the image forming apparatus 6, standard calibration data set in advance is set in the calibration table 45 </ b> B even when the calibration process is not performed.

  The patch data 46 stores gradation patch data used during the calibration process. The evaluation data storage unit 47 stores tone evaluation image data for evaluating color and a chart for outputting a calibration result. The read data storage unit 48 stores read data obtained by reading an image with a color sensor 54A of the printer engine 5 described later.

  The printer engine 5 performs processing for outputting a printed matter under the control of the job control unit 41. The printer engine 5 includes a communication I / F unit 50, an operation unit 51, a calibration setting selection unit 52, a target color data selection unit 53, a color sensor control unit (transfer belt unit) 54, a color sensor 54A, and a read data storage unit. 55 and an output unit 56.

  The communication I / F unit 50 is connected to the front end server 4 and exchanges data with the front end server 4. The operation unit 51 is a user I / F that receives input information in accordance with operations of the calibration setting selection unit 52 and the target color data selection unit 53 that are input devices. The calibration setting selection unit 52 accepts selection of settings for calibration processing. The target color data selection unit 53 receives input of target color information required for an image formed on a medium.

  The color sensor control unit 54 controls the color sensor 54A that separates the output gradation patch into RGB and reads it at the color level. The output unit 56 has a function of forming an image of data subjected to tone correction processing by the tone correction processing unit 45 on a medium and outputting the medium, and outputs a printed matter corresponding to job data. The job control unit 41 controls the output unit 56 to form a gradation evaluation image on the medium after the calibration process.

  Next, the proof printing output process in the image forming system 1 will be described with reference to FIG. FIG. 3 is a flowchart showing a processing procedure of proof printing output processing in the image forming system shown in FIG.

  As shown in FIG. 3, first, job data transmission processing is performed in which job data is transmitted to the front-end server 4 (step S1-1). This job data is print job data that also contains information about the target color by the SE or client on the remote transmission side of the site A1, and is remotely transmitted from the terminal device 2 to the front-end server 4 via the network N. . Note that job data may be directly transmitted from the operation unit 51 of the printer engine 5 to the front-end server 4 by an operation of a client on the remote reception side of the site A2.

  In the front end server 4, the job management unit 41A temporarily holds the image processing and output processing instructed by the received job data (step S1-2). Subsequently, the job analysis unit 41B analyzes the job ticket data in the job data (step S1-3), and the job control unit 41 determines a process to be executed from now on, a layout at the time of job data output, and the like. . The job ticket data includes a paper size, a paper direction, a paper type, calibration data setting information, target color information, and the like.

  First, the job control unit 41 extracts the calibration data setting information from the job ticket data based on the analysis result in the job analysis unit 41B, and determines whether or not the execution of the calibration process is instructed (step). S1-4).

  When the job control unit 41 determines that the execution of the calibration process is not instructed (step S1-4: No), the job control unit 41 releases the hold of the job data and uses the image instructed by the job data so far. Job data that causes the tone correction processing unit 45 to perform tone correction processing to which the calibration data in the calibration table that has been applied is applied, and prints and outputs the image after tone correction from the output unit 56 on paper. An output process is performed (step S1-5).

  On the other hand, when the job control unit 41 determines that the execution of the calibration process is instructed (step S1-4: Yes), a patch output process for outputting the gradation patch to the printer engine 5 is performed (step S1- 6). In the patch output process, the gradation patch in the patch data storage unit 46 is printed on paper and output, and the output gradation patch is read by the color sensor 54A. Subsequently, the image forming apparatus 6 performs calibration data generation processing (step S1-7). As the calibration data generation processing, the calibration data generation unit 42 uses each density conversion data of the read data of the output patch to approximate each target gradation according to the target color in the job ticket data. Calibration data including gradation correction data with optimized parameters is generated as first calibration data. Note that the calibration data used in the calibration process before the generation of the first calibration data is stored in the calibration data storage unit 42A as second calibration data, as will be described later.

  After step S1-6 is completed, the job control unit 41 performs job data output processing for releasing the job data held by the job management unit 41A and causing the output unit 56 to output the job data (step S1-8). ). In this job data output process, the job control unit 41 uses the first gradation evaluation image whose gradation is corrected using the newly generated first calibration data and the first gradation evaluation image that has been used so far. The third and third gradation values having gradation values near the gradation of the first evaluation image together with the second gradation evaluation image in which the gradation before the calibration process is reproduced using the calibration data of 2. 4 is prepared for gradation evaluation image data. The third gradation evaluation image has a gradation value (−1) that is one step lower than the gradation of the first evaluation image, and the fourth gradation evaluation image is the first evaluation image. It has a gradation value (+1) that is one step higher than the gradation of the image. Then, the job control unit 41 causes the output unit 45 to print these first to fourth gradation evaluation images on a sheet. In the job data output process, first to fourth gradation evaluation image data are prepared, and aggregate printing is performed by collecting a plurality of data on one sheet. Therefore, the job control unit 41 prepares image data of each of the first to fourth gradation evaluation images, and executes a print job for each gradation evaluation image.

  Subsequently, the job control unit 41 determines whether or not the output image has achieved SE or the color desired by the client (step S1-9). For example, when the operation unit 51 has a display, the user is prompted to select whether or not the color of the output image has achieved the desired color, and the image that achieves the desired color is the first. A menu screen that can be selected from the first to fourth gradation evaluation images is displayed. The operation unit 51 selects information indicating whether or not a color has been achieved or an image for gradation evaluation that achieves the desired color best according to the operation of the input device of the operation unit 51 by the SE or the client. Accept the information. Based on the received selection information, it is determined whether or not the output image has achieved SE or the color desired by the client.

  If the job control unit 41 determines that the output image has achieved the desired color of the SE or the client (step S1-9: Yes), the job control unit 41 requests the SE or the client via the operation unit 51 or the network N. The information of the gradation evaluation image selected as achieving the best color is received. In this case, the job control unit 41 assumes that the calibration data corresponding to the gradation evaluation image has been selected (step S1-10), and the calibration data generation unit 42 calibrates the selected calibration data. The proof printing output process is completed.

  On the other hand, when the job control unit 41 determines that none of the output first to fourth gradation evaluation images has achieved the color desired by the SE or the client (step S1- 9: No), gradation correction data transmission / reception processing is performed (step S1-12). In the gradation correction data transmission / reception process, the front-end servers 3 and 4 transmit the request information indicating the target of the color desired by the SE or the client to the calibration data design side, and are transmitted from the designer side accordingly. New recommended gradation correction data Se is received. On the client side, the network I / F unit 41 of the front-end server 3 receives the new recommended gradation correction data Se transmitted from the calibration data design side, and the received recommended gradation correction data Se is applied to the gradation characteristics. Store in the data storage unit 45A. Thereafter, the process returns to step S1-1, and tone correction is performed using the tone of the image when the tone correction is performed with the calibration data including the recommended tone correction data Se and the second calibration data. In order to compare the color of the image in this case, a print job including a calibration data setting instruction is transmitted. In this case, in the image forming apparatus 6, Steps S1-6 and S1-7 are omitted, and in Step S1-8, the calibration data generation unit 42 receives the calibration data including the recommended gradation correction data Se for the first time. The gradation before the calibration processing is reproduced using the first gradation evaluation image obtained by the first calibration data and subjected to gradation correction using the first calibration data and the second calibration data. The second gradation evaluation image is collectively printed on the same sheet. In the image forming system 1, the above process is repeated by trial and error, so that an image closer to the client's desire can be provided. Note that the calibration data design side may prepare gradation correction data of several patterns in advance in a library format to widen the range of color choices desired by the client. In this case, the image forming apparatus 6 stores a plurality of prepared gradation correction data in the gradation characteristic data storage unit 45A, and applies gradation data including each gradation correction data to perform gradation correction. The multiple gradation evaluation images that have been performed are collectively printed together with the second gradation evaluation image, and the gradation correction result based on each calibration data is presented to the SE or client.

  Next, the job data transmission process shown in FIG. 3 will be described with reference to FIG. FIG. 4 is a flowchart showing a processing procedure of the job data transmission process shown in FIG. As shown in FIG. 4, the terminal device 2 selects whether or not to execute calibration data, information on target color, and the like by an operation by the SE or client on the remote transmission side (step S2-1). As described above, the client on the remote reception side of the site A2 may select a target color by operating the operation unit 51 of the printer engine 5.

  Then, job data having contents corresponding to the selection process in step S2-1 is transmitted from the terminal device 2 or the printer engine 5 to the front-end server 4 (step S2-2). The job data includes job ticket data. The job ticket data includes paper setting information, evaluation data setting information, and the like in addition to the calibration data setting information and target color information selected in step S2-1, and an item for instructing the content of processing. Is described. In the present embodiment, the respective tone evaluation images before and after calibration for comparing the colors of the images before and after calibration are printed on the same sheet. The operation unit of the terminal device 2 or the printer engine 5 can select the print format of each gradation evaluation image before and after the calibration, and the evaluation data setting information includes the gradation evaluation image data before and after the calibration. The output format is set.

  Next, the patch data output process shown in FIG. 3 will be described with reference to FIG. FIG. 5 is a flowchart showing a processing procedure of the patch data output process shown in FIG. As shown in FIG. 5, the front-end server 4 extracts the gradation patch data from the patch data storage unit 46 (step S <b> 3-1), and the gradation correction processing unit 45 adds the calibration table to the extracted gradation patch data. The gradation correction processing is performed using the calibration data set in (Step S3-2). In this case, since the calibration process is not performed, the calibration data is not changed.

  Then, the gradation patch data after gradation correction is developed into bitmap image data by the rendering unit 44 (step S3-3), and the paper setting in which the developed bitmap image data and the paper type in the job ticket data are set. Information is transferred to the printer engine 5 (step S3-4).

  The printer engine 5 selects a sheet based on the sheet setting information transferred from the front-end server 4 and prints a gradation patch on the selected sheet (step S3-5). The color sensor control unit 54 reads the gradation patch printed on the paper with the color sensor 54A, and stores the read data in the read data storage unit 55 (step S3-6). Subsequently, the printer engine 5 transfers the read data to the read data storage unit 48 on the front end server 4 side via the communication I / F unit 50 (step S3-7). The front-end server 4 stores the transferred read data in the read data storage unit 48 (step S3-8), and ends the patch data output process.

  Next, the calibration data generation process shown in FIG. 3 will be described with reference to FIG. FIG. 6 is a flowchart showing a processing procedure of the calibration data generation process shown in FIG. As shown in FIG. 6, the calibration data generation unit 42 retrieves the read data of the patch read at the RGB level from the read data storage unit 48 (step S4-1), and converts it into CMYK density data (step S4-1). Step S4-2).

  Based on the target color information in the job ticket data of the job data, the calibration data generation unit 42 sets the target gray level according to the target color to the target gray level of the gray level characteristic data storage unit 45A. Select from characteristic data. Based on the density data and the target gradation selected from the target gradation characteristic data, the calibration data generation unit 42 optimizes the gradation correction parameters so that the density data approximates the target gradation. Calibration data including tone correction data is generated (step S4-3).

  The calibration data generation unit 42 holds this as first calibration data. Furthermore, the calibration data generation unit 42 also creates calibration data corresponding to the gradation values near the generated first calibration data (step S4-4). In other words, in step S4-4, the calibration data generation unit 42 corrects the gradation of the image so as to have a gradation value near the gradation of the image when the first calibration data is applied. Tone correction data that can be generated is generated. For example, the calibration data generation unit 42 sets the third calibration data in which parameters are set so that the gradation value (−1) is one step lower than the gradation of the first calibration data, and this Fourth calibration data in which parameters are set so as to have a gradation value (+1) that is one step higher than the gradation of the first calibration data is generated. The calibration data generation unit 42 stores the first, third, and fourth calibration data in the calibration data storage unit 42A (step S4-5). In the calibration generation process, the second calibration data before calibration is still set in the calibration table 45B. The second calibration data is stored separately from the first, third, and fourth calibration data in the job data output process described later.

  Next, the job data output process shown in FIG. 3 will be described with reference to FIG. FIG. 7 is a flowchart showing a processing procedure of the job data output process shown in FIG. In the job data output process shown in FIG. 7, as described above, a plurality of gradation evaluation image data are prepared and printed on one sheet. Therefore, a job is set for each tone evaluation image data.

  For this reason, the job control unit 41 first releases the hold of the job corresponding to the second gradation evaluation image in order to restart the output processing of the plurality of job data held in the job management unit 41A (step S1). S5-1), the tone evaluation image data for color evaluation is extracted from the evaluation data storage unit 47 (step S5-2), and the job analysis unit 41A uses the job ticket data in the job data. Is analyzed (step S5-3).

  The job control unit 41 determines whether or not the job reflecting the second calibration data before the calibration process has been executed before the gradation correction processing unit 45 performs the gradation correction process ( Step S5-4). Since the current job is a job corresponding to the second tone evaluation image, the job control unit 41 determines that the job reflecting the second calibration data has not been executed (step S5-4). : No), the correction processing unit 45 is caused to execute gradation correction processing to which the calibration data of the calibration table 45B is applied to the data of the gradation evaluation image (step S5-7). At this time, since the second calibration data is still set in the calibration table 45B, the second gradation evaluation image to which the second calibration data before calibration is applied is generated. It becomes. Subsequently, the job control unit 41 causes the rendering unit 44 to develop the second tone evaluation image data after the tone correction processing into bitmap image data (step S5-8), and this bitmap image data. And the paper setting information in which the paper type and the like in the job ticket data are set are transferred to the printer engine 5 (step S5-9). The printer engine 5 selects a sheet based on the sheet setting information transferred from the front end server 4, and prints a second tone evaluation image on the selected sheet (step S5-10). Since this printing is aggregate printing, as shown in FIG. 8, for example, for the second gradation evaluation in which the gradation before calibration is reproduced in the upper left area of one sheet P1 divided into four equal parts. Image A12 is printed.

  Subsequently, the job control unit 41 determines whether or not all jobs have been completed (step S5-11). In this case, since the jobs of the first, third, and fourth tone evaluation images remain, the job control unit 41 determines that all jobs are not completed (step S5-11). : No), printing of the first gradation evaluation image is started. Therefore, the job corresponding to the first gradation evaluation image held in the job management unit 41A is released (step S5-1), and the processes of steps S5-2 to S5-4 are performed. Then, the job control unit 41 determines that the job reflecting the second calibration data has been executed (step S5-4: Yes), and is set in the calibration table 45B in the calibration generation unit 42. The second calibration data is stored in the calibration data storage unit 42A (step S5-5). Subsequently, the job control unit 41 causes the calibration data generation unit 42 to set the first generated calibration data to the calibration table 45B (step S5-6), and causes the correction processing unit 45 to execute the calibration table. A gradation correction process to which the first calibration data of 45B is applied is executed for the gradation evaluation image data (step S5-7). Therefore, a first tone evaluation image to which the first calibration data is applied is generated. Subsequently, the image forming apparatus 6 performs the processes of steps S5-8 to S5-10, and the first gradation evaluation image is the same sheet as the sheet on which the second gradation evaluation image is printed. Print on. In the example of FIG. 8, the first gradation evaluation image A11 to which the first calibration data is applied is printed in the lower left area of the paper P1.

  Then, in order to print the third tone evaluation image, the job control unit 41 determines that all jobs are not completed (step S5-11: No), and holds it in the job management unit 41A. The hold of the job corresponding to the tone evaluation image 3 is released (step S5-1), and the processing of step S5-2 to step S5-4 is performed. Then, as in the case of the first gradation evaluation image, the job control unit 41 determines that the job in which the second calibration data has been reflected has already been executed (step S5-4: Yes), The calibration data generation unit 42 stores the first calibration data set in the calibration table 45B in the calibration data storage unit 42A (step S5-5). The job control unit 41 causes the calibration data generation unit 42 to set the third calibration data in the calibration table 45B (step S5-6), and causes the correction processing unit 45 to perform the third calibration of the calibration table 45B. The gradation correction process using the application data is executed for the gradation evaluation image data (step S5-7), and the gradation value is one step lower than the gradation of the first gradation evaluation image. A third tone evaluation image having the above is generated. Subsequently, the image forming apparatus 6 performs the processes in steps S5-8 to S5-10, and the third gradation evaluation image is the same sheet as the sheet on which the second gradation evaluation image is printed. Print on. In the example of FIG. 8, the third gradation evaluation image A13 is printed in the upper right area of the paper P1.

  Similarly, the job control unit 41 releases the hold of the job corresponding to the fourth tone evaluation image held in the job management unit 41A in order to print the fourth tone evaluation image (step S5- 1) Steps S5-2 to S5-5 are performed, and the calibration data generation unit 42 stores the third calibration data of the calibration table 45B in the calibration data storage unit 42A (step S5- 5) The fourth calibration data is set (step S5-6). Then, the job control unit 41 causes the correction processing unit 45 to perform gradation correction processing using the fourth calibration data in the calibration table (step S5-7), and the first gradation evaluation image. A fourth gradation evaluation image having a gradation value that is one step higher than the gradation is generated. Subsequently, the image forming apparatus 6 performs the processes of steps S5-8 to S5-10, and the fourth tone evaluation image is the same as the paper on which the first to third tone evaluation images are printed. Print on paper. In the example of FIG. 8, the fourth tone evaluation image A14 is printed in the lower right area of the paper P1.

  Then, the job control unit 41 determines that all jobs have been completed (step S5-11: Yes), and outputs from the output unit 56 of the printer engine 5 first to fourth tone evaluation images that are job data. Is output (step S5-12), and the job data output process is terminated. In the process of FIG. 7, since aggregate printing is performed, the information of one job data can be reduced and each gradation evaluation image can be output earlier. In addition, when information on a change in the printing environment on the client side such as a change in paper type is entered, background processing or the like is additionally performed on the server to output image data and improve image quality.

  Then, referring to FIG. 9, the process is performed when it is determined that none of the output first to fourth gradation evaluation images has achieved the color desired by the SE or the client. The gradation correction data transmission / reception process will be described. FIG. 9 is a flowchart showing a processing procedure of the gradation correction data transmission / reception processing shown in FIG.

  As shown in FIG. 9, the request information indicating the color target desired by the SE or the client is transmitted from the terminal device 2 or the terminal device 7 on the client side via the network 3 to the front-end server on the calibration data design side. 8 (step S8-1). The front-end server 8 receives this request information, and in the terminal device 9 operated by the designer, a new tone correction parameter is optimized by following the desired color indicated by the request information. Tone correction data is prepared (step S8-2). The front end server 7 transmits this gradation correction data as recommended gradation correction data Se to the client side front end servers 3 and 4 via the network N (step S8-3). The front end servers 3 and 4 store the recommended gradation correction data Se in the gradation characteristic data storage section of the front end server 4 (step S8-4). In response to this, the image forming apparatus 6 restarts the calibration process and repeats the above in a trial and error format so that an image closer to the desired color can be provided. As described above, the designer side may prepare several patterns of gradation correction data in a library format in advance, and first widen the range of color choices desired by the client.

  As described above, in the present embodiment, in this embodiment, the tone evaluation image before the calibration process in addition to the calibration process is printed on the same sheet. It is presented to the SE or client in an easy-to-understand manner. Therefore, by checking this paper, whether the client side SE or the client itself can actually print with the desired color by calibration, and the color of the printed matter is calibrated. It is possible to clearly determine how much improvement has been made compared to the previous one.

  In this embodiment, a gradation evaluation image having gradations near the gradation after calibration is also printed on the same sheet as the gradation evaluation images before and after calibration, and gradations by SE or Klein The range of choices can be expanded. Therefore, the SE or the client can easily match the color of the printed matter to the desired color by selecting an image that achieves the desired color best from these images for gradation evaluation. it can.

  Furthermore, in the embodiment, the transmission / reception of the request information and the gradation correction data corresponding to the request information is performed with the calibration data design side so that an image closer to the desired color can be provided. Therefore, the SE or the client can surely acquire the gradation correction data that matches the desired color and can adjust the color of the printed matter to the desired color.

(Modification 1 of embodiment)
In the job data output process of FIG. 7, a case has been described in which the first to fourth gradation evaluation images are simultaneously output in an aggregate print, but the first to fourth gradation evaluation images are manually printed. Of course, it is also possible to print on the same paper. When manual feed printing is performed, four jobs of first to fourth gradation evaluation images are prepared as in the case of collective printing. Job data output processing when performing manual feed printing will be described with reference to FIG. Steps S6-1 to S6-10 in FIG. 10 are steps S5-1 to S5-10 in FIG. When the output unit 56 outputs a sheet on which any of the first to fourth gradation evaluation images, which are job data, is printed (step S6-11), the job control unit 41 displays all the jobs. Is determined whether or not (step S6-12: No). If the job control unit 41 determines that all jobs have not been completed (step S6-12: No), for example, on the display of the operation unit 51 of the printer engine 5, on the manual feed tray, for gradation evaluation of the previous job. A notification that prompts the user to replenish the paper on which the image is printed for the next gradation evaluation image is output (step S6-13). If the job control unit 41 recognizes that a sheet is set on the manual feed tray, the process returns to step S6-1 to perform processing for the next job. If the job control unit 41 determines that all jobs have been completed (step S6-12: Yes), it ends the job data output process.

(Modification 2 of embodiment)
In the job data output process, each gradation evaluation image is printed as an independent image on one sheet, and the gradation correction is performed by applying the first to fourth calibration data. One image combining the images may be printed.

  In the image forming apparatus 6, as illustrated in FIG. 11, the gradation image G <b> 2 arranged so that the first to fourth gradation evaluation images are arranged in the order of the presence / absence of the calibration process and the density is used as the gradation evaluation image. Printing is performed on one sheet of paper P2. The division number and the division shape of the gradation image G2 are set in advance according to the number of gradation evaluation images, whether or not calibration processing is performed, and the gradation of each gradation evaluation image. Sets the gradation correction data to be applied to each divided portion in accordance with the presence / absence of execution of the calibration process and the gradation of the image after the gradation correction process. In the example of the gradation image G2 in FIG. 11, the job control unit 41 divides a large square in a nested manner, applies the second calibration data to the central square portion A22, and applies the third calibration data to the frame portion A23. The calibration data is applied, the first calibration data is applied to the frame portion A21, the fourth calibration data is applied to the frame portion A24, and the gradation correction processing unit 45 performs the gradation correction processing. Let it be done. As a result, the second gradation evaluation image reproducing the gradation before calibration is arranged in the square part A22 at the center of the output gradation image G2, the frame part A25 is removed, and the calibration is performed in the frame part A23. A third gradation evaluation image having a gradation value (−1) one level lower than the gradation after the calibration is arranged, and the first gradation evaluation image of the gradation after the calibration is arranged in the frame portion A21. In the frame portion A24, a fourth gradation evaluation image having a gradation value (+1) that is one step higher than the gradation after calibration is disposed. In this gradation image G2, since the second to fourth gradation evaluation images are arranged in order of light and shade from the center to the outside, the SE or the client can easily compare the colors of the images. Can do. Further, as shown in FIG. 12, the job control unit 41 causes the output unit 56 to print the gradation image G3 with the four corners of the gradation image G2 in FIG. Toner save may be performed.

  Note that job data output processing in the case where a gradation image in which images after application of the first to fourth gradation correction data are applied according to the order of shading is output as a gradation evaluation image will be described. FIG. 13 is a flowchart showing another processing procedure of the job data output process shown in FIG. In this case, the gradation evaluation image is divided into a plurality of parts, and the job control unit 41 determines each divided part according to whether or not the calibration process is performed and the gradation of the image after the gradation correction process. Set gradation correction data to be applied to. The gradation correction processing unit 45 corresponds to any one of the first to fourth gradation correction data according to the setting of the gradation correction data of the job control unit 41 for each divided portion of the gradation evaluation image. The job control unit 41 applies the correction data to perform tone correction processing, and the job control unit 41 uses one image obtained by combining the respective divided portions subjected to the tone correction processing by the tone correction processing unit 45 for tone evaluation. The image is printed on the output unit 56 as an image. Therefore, in the second modification, the gradation correction process is divided for each part in one job.

  For this reason, as shown in FIG. 13, the job control unit 41 releases the hold of the job (step S7-1), and takes out the data of the gradation evaluation image from the evaluation data storage unit 47 (step S7-2). ). Then, the job analysis unit 41A analyzes the job ticket data in the job data (step S7-3). Here, in the job ticket data, the gradation applied to each divided portion according to the division shape and number of divisions of the gradation evaluation data, whether or not calibration processing is performed, and the gradation of the image after the gradation correction processing It includes information in which the type of correction data is set.

  Subsequently, under the control of the job control unit 41, the calibration data generation unit 42 calibrates each calibration data having the first, third, and fourth tone correction data set in the job ticket data. The data is taken out from the calibration data storage unit 42A and set in the calibration table 45B (step S7-4). In this case, a plurality of tables are provided as the calibration table 45B, the second calibration data already set in the calibration table is held as it is, and the first and first calibration tables are stored in the empty calibration table. Third and fourth calibration data are set.

  The job control unit 41 determines whether or not all the first to fourth calibration data are set in the calibration table (step S7-5). When the job control unit 41 determines that all the first to fourth calibration data are not set in the calibration table (step S7-5: No), the job control unit 41 returns to step S7-4 and sets it. Unused calibration data is also set in an empty calibration table.

  If the job control unit 41 determines that all of the first to fourth calibration data have been set in the calibration table (step S7-5: Yes), the tone correction processing unit 45 performs the tone evaluation. The gradation correction data of the calibration data table is applied to the target part of the divided part of the image (step S7-6). As described above, the job ticket data of the job data includes in advance information such as which calibration table the calibration data is applied to which divided portion of the gradation evaluation image. The gradation correction processing unit 45 retrieves calibration data including gradation correction data corresponding to the divided portion to be processed from each of the plurality of calibration tables, and executes gradation correction processing. As a technique for performing gradation correction by associating the target portion to be subjected to gradation correction with the calibration data to be applied, from the position information of the xml data, from the information on the association of calibration data based on this position, A method of applying gradation correction processing for each position by distinguishing gradation correction data to be applied, and calibration data that can realize this gradation value from the gradation value (bit number data) of the evaluation data image There is a method of performing gradation correction processing by distinguishing applicable gradation correction data from the attached information.

  The job control unit 41 determines whether or not gradation correction has been performed on all image data of gradation evaluation data (step S7-7). If the job control unit 41 determines that all of the image data of the gradation evaluation data has not been subjected to gradation correction (step S7-7: No), the process returns to step S7-6, and the gradation correction processing unit 45 receives the gradation. The gradation correction process is executed on the remaining divided portions of the evaluation image.

  On the other hand, when the job control unit 41 determines that all of the image data of the gradation evaluation data has been subjected to the gradation correction (step S7-7: Yes), the job evaluation unit 41 performs the gradation evaluation image after the gradation correction. The rendering unit 44 develops the data into bitmap image data (step S7-8). Then, the job control unit 41 transfers the bitmap image data and the paper setting information to the printer engine 5 (step S7-9). The printer engine 5 selects a sheet based on the sheet setting information transferred from the front-end server 4 and displays a gradation image in which the first to fourth gradation evaluation images of each gradation are combined with one image. Printing as a tone evaluation image (step S7-10). Then, the paper on which the gradation image is printed is output from the output unit 56 (step S7-11), and the job data output process is terminated.

  In the present embodiment, the case where the first to fourth gradation evaluation images are printed on the same sheet has been described. Of course, the first gradation evaluation image and the second gradation evaluation image are not limited to this. May be printed on the same sheet, and in addition to the first to fourth gradation evaluation images, gradation evaluation images having different gradation values may be printed on the same sheet. You may print on.

  A configuration example of the image forming apparatus 6 will be described. FIG. 14 is a diagram illustrating a configuration of an example of an image forming apparatus 500 applicable to the present embodiment. As shown in FIG. 14, the image forming apparatus 500 has a configuration in which a controller 510 and an engine unit (Engine) 560 are connected by a PCI (Peripheral Component Interconnect) bus. The controller 510 is a controller that controls the entire image forming apparatus 6 and controls drawing, communication, and input from an operation unit (not shown). The engine unit 560 is a printer engine that can be connected to a PCI bus, and is, for example, a monochrome plotter, a one-drum color plotter, a four-drum color plotter, a scanner, or a fax unit. The engine unit 560 includes an image processing part such as error diffusion and gamma conversion in addition to a so-called engine part such as a plotter.

  The controller 510 includes a CPU 511, a north bridge (NB) 513, a system memory (MEM-P) 512, a south bridge (SB) 514, a local memory (MEM-C) 517, and an ASIC (Application Specific Integrated Circuit). 516 and a hard disk drive (HDD) 518, and the North Bridge (NB) 513 and the ASIC 516 are connected by an AGP (Accelerated Graphics Port) bus 515. The MEM-P 512 further includes a ROM (Read Only Memory) 512a and a RAM (Random Access Memory) 512b.

  The CPU 511 controls the entire image forming apparatus 500 and is connected to other devices via a chip set including the NB 513, the MEM-P 512, and the SB 514.

  The NB 513 is a bridge for connecting the CPU 511 to the MEM-P 512, the SB 514, and the AGP bus 515, and includes a memory controller that controls reading and writing of the MEM-P 512, a PCI master, and an AGP target.

  The MEM-P 512 is a system memory used as a memory for storing programs and data, a memory for developing programs and data, a memory for drawing a printer, and the like, and includes a ROM 512a and a RAM 512b. The ROM 512a is a read-only memory used as a program / data storage memory, and the RAM 512b is a writable / readable memory used as a program / data development memory, a printer drawing memory, or the like.

  The SB 514 is a bridge for connecting the NB 513 to a PCI device and peripheral devices. The SB 514 is connected to the NB 513 via a PCI bus, and a network interface (I / F) unit and the like are also connected to the PCI bus.

  The ASIC 516 is an image processing application IC (Integrated Circuit) having hardware elements for image processing, and has a role of a bridge for connecting the AGP bus 515, the PCI bus, the HDD 518, and the MEM-C 17. The ASIC 516 includes a PCI target and an AGP master, an arbiter (ARB) that is the core of the ASIC 516, a memory controller that controls the MEM-C 517, and a plurality of DMACs (Direct Memory) that perform image data rotation by hardware logic and the like. Access Controller) and a PCI unit for transferring data between the engine unit 560 via the PCI bus. An FCU (Fax Control Unit) 530, a USB (Universal Serial Bus) 540, and an IEEE 1394 interface 550 are connected to the ASIC 516 via a PCI bus. The operation display unit 520 is directly connected to the ASIC 516.

  A MEM-C 517 is a local memory used as a copy image buffer and a code buffer, and an HDD (Hard Disk Drive) 518 is a storage for storing image data, programs, font data, and forms. It is.

  The AGP bus 515 is a bus interface for a graphics accelerator card proposed for speeding up graphics processing. The AGP bus 515 speeds up the graphics accelerator card by directly accessing the MEM-P 512 with high throughput. It is.

  In addition, an execution program for each process executed by the image forming apparatus 6 and other components of the image forming system 1 according to the present embodiment is an installable format or executable format file that is a CD-ROM, flexible It may be configured to be recorded on a computer-readable recording medium such as a disk (FD), CD-R, or DVD (Digital Versatile Disk), and stored on a computer connected to a network such as the Internet. However, the program may be provided by being downloaded via a network. Further, it may be configured to be provided or distributed via a network such as the Internet.

DESCRIPTION OF SYMBOLS 1 Image forming system 2, 7, 9 Terminal device 3, 4, 8 Front end server 5 Printer engine 6 Image forming apparatus 40 Network I / F part 41 Job control part 41A Job management part 41B Job analysis part 42 Calibration data generation part 42A Calibration data storage unit 43, 50 Communication I / F unit 44 Rendering unit 45 Gradation correction processing unit 45A Gradation characteristic data storage unit 45B Calibration table 46 Patch data storage unit 47 Evaluation data storage unit 48, 55 Read data Storage unit 51 Operation unit 52 Calibration setting selection unit 53 Target color data selection unit 54 Color sensor control unit 54A Color sensor 56 Output unit 510 Controller 511 CPU
512 MEM-P
513 NB
514 SB
515 AGP bus 516 ASIC
517 MEM-C
518 HDD
520 Operation display section 530 FCU
540 USB
550 IEEE1394 interface 560 engine part

Japanese Patent No. 3243397 Japanese Patent No. 4764458 Japanese Patent No. 4274544

Claims (15)

Gradation correction processing means for performing gradation correction processing on input image data using gradation correction data;
Output means for forming an image of data subjected to gradation correction processing by the gradation correction processing means on a medium and outputting the medium;
Calibration means for executing calibration processing for calibrating the gradation correction data used by the gradation correction processing means so that the gradation of the image formed on the medium becomes a target gradation according to a target color;
Control means for causing the output means to form an image for gradation evaluation on the medium after the calibration processing by the calibration means;
Storage means for storing data required for the gradation correction processing;
With
The calibration means is a gradation correction for approximating the gradation of the image formed on the medium to the target gradation based on the density conversion data of the reading data of the gradation patch formed on the medium. The data is acquired as the first gradation correction data, and the gradation correction data used in the gradation correction process before acquiring the first gradation correction data is used as the second gradation correction data. Memorize it in the memory means,
The control means includes a first gradation evaluation image obtained by causing the output processing means to correct a gradation using the first gradation correction data, and the second gradation. An image forming apparatus characterized in that a second gradation evaluation image in which gradations before calibration processing are reproduced using correction data is formed on the same medium.   2. The image forming apparatus according to claim 1, wherein the calibrating unit stores the first gradation correction data in the storage unit together with the second gradation correction data. The calibration means acquires third gradation correction data that can correct the gradation of the image so as to have a gradation value in the vicinity of the gradation of the first gradation evaluation image. The stored third gradation correction data in the storage means,
The control unit causes the output unit to output the third gradation evaluation image obtained by correcting the gradation using the third gradation correction data by the gradation processing unit. The image forming apparatus according to claim 1, wherein the image forming apparatus is formed on the same medium together with a tone evaluation image and the second tone evaluation image. After the medium on which the plurality of gradation evaluation images are formed is output by the output means, any one of the plurality of gradation evaluation images formed on the medium that has achieved a target color A selection unit for receiving selection of the image for gradation evaluation;
The calibration means uses, as gradation correction data used by the gradation correction processing means, gradation correction data corresponding to the gradation evaluation image received by the selection unit from among the plurality of gradation evaluation images. The image forming apparatus according to claim 1, wherein the image forming apparatus is set. Information receiving means for receiving input of target color information required for an image formed on the medium;
A communication means for communicating information with an external design apparatus via a network;
Further comprising
The communication unit transmits request information including target color information received by the information receiving unit to the external design apparatus, and a gradation transmitted from the external design apparatus in response to the request information. Receive correction data,
5. The image forming apparatus according to claim 1, wherein the calibration unit acquires the gradation correction data received by the communication unit as the first gradation correction data. There are a plurality of gradation correction data transmitted from the external design apparatus in response to the request information,
The image forming apparatus according to claim 5, wherein the storage unit stores a plurality of gradation correction data received by the communication unit. The storage means stores target gradation characteristic data indicating a gradation index corresponding to each target color,
The calibration means selects a target gradation according to the target color received by the information receiving means by referring to target gradation characteristic data stored in the storage means. The image forming apparatus according to 5.   The control means outputs, to the output means, a plurality of gradation evaluation images that have undergone gradation correction processing using the gradation correction data in the gradation correction processing means on the same medium by aggregate printing. The image forming apparatus according to claim 1, wherein the image forming apparatus is formed. A notification means for notifying the supply of the medium;
The control means is a medium on which the gradation evaluation image has been formed from any of the plurality of gradation evaluation images that have been subjected to gradation correction processing using the gradation correction data in the gradation correction processing means. The image forming apparatus according to any one of claims 1 to 7, wherein the notification unit outputs a notification that prompts the user to supply the image again for forming a next gradation evaluation image. The gradation evaluation image is divided into a plurality of parts,
The gradation correction processing means performs gradation correction processing by applying the gradation correction data corresponding to any of the plurality of gradation correction data, for each divided portion of the gradation evaluation image,
The control unit forms, as the gradation evaluation image, on the medium on the medium as the gradation evaluation image, which is a combination of the divided portions that have been subjected to the gradation correction processing by the gradation correction processing unit. The image forming apparatus according to claim 1, wherein the image forming apparatus is an image forming apparatus. The number of divisions and the division shape of the gradation gradation evaluation image are preset,
The control means sets gradation correction data to be applied to each divided portion according to whether or not the calibration process is executed and the gradation of the image after the gradation correction process. The image forming apparatus described in 1.   The image forming apparatus according to claim 11, wherein the control unit causes the output unit to form an image with a part of the gradation evaluation image cut out on the medium. Further comprising an instruction receiving means for receiving an instruction to execute the calibration process;
The image forming apparatus according to claim 1, wherein the command receiving unit receives an execution command for the calibration process via a network. An image forming apparatus according to any one of claims 1 to 13,
Gradation that is connected to the image forming apparatus via a network, receives request information including target color information transmitted from the image forming apparatus via the network, and is generated according to the request information A design apparatus for transmitting correction data to the image forming apparatus;
An image forming system comprising: An image forming method for causing an image forming apparatus to form an image of data on which gradation correction has been performed on a medium and outputting the medium,
A tone correction step for correcting the tone using the tone correction data for the input image data;
A calibration step for calibrating the gradation correction data used in the gradation correction step so that the gradation of the image formed on the medium becomes a target gradation according to a target color;
An output step of forming and outputting an image for gradation evaluation on the medium after the calibration step;
Including
The calibration step includes
Tone correction data for approximating the tone of the image formed on the medium to the target tone based on the density conversion data of the read data of the tone patch formed on the medium is the first. A first gradation correction data acquisition step acquired as gradation correction data;
Second gradation correction data storage for storing the gradation correction data used in the gradation correction processing before obtaining the first gradation correction data in a predetermined storage means as second gradation correction data. Steps,
Including
The output step is calibrated using the first gradation evaluation image whose gradation has been corrected using the first gradation correction data in the gradation correction step and the second gradation correction data. An image forming method comprising: forming a second gradation evaluation image in which a gradation before processing is reproduced on the same medium.

Images