JP2013110452A - Determination method and recorder - Google Patents

Abstract

PROBLEM TO BE SOLVED: To determine whether or not calibration which is not dependent on the skill of an administrator is required, at a low cost.SOLUTION: A determination method for determining whether or not calibration is required includes: a setting step for setting a threshold of determining whether or not calibration is required; an acquisition step for recording a check chart consisting of a plurality of patches composed of a smaller number of patches than the number of patches composing a calibration chart, and composed of the patches composing the calibration chart, and acquiring a colorimetric value by measuring the respective patches of the check chart by colorimetric means; and a determination step for determining whether or not calibration is required on the basis of a prestored target colorimetric value of the patches of a check chart, the colorimetric value acquired in the acquisition step, and the threshold.

Description

  The present invention relates to a determination method and a recording apparatus that determine whether calibration needs to be executed.

  In general, calibration of an ink jet recording apparatus is performed by recording a calibration chart in order to examine recording density characteristics for each color material color, measuring the recorded chart, and setting each color so as to obtain preset recording density characteristics. The correction parameter is calculated with the material color. Then, by correcting the recording density using the calculated correction parameter, recording is performed with the color of the recording result constant.

  Since normal calibration needs to be executed when the color of the recording apparatus varies, the necessity of the calibration is determined by visually determining the color variation of the recording medium. Further, it is periodically executed at a timing calculated based on a change cycle of the apparatus found out when the parts such as the coloring material and the head are replaced or empirically.

  However, in the visual determination method, the determination criterion of color variation is ambiguous, and the recording accuracy may vary depending on the skill of the manager. In addition, in the calculation method based on the knowledge of device fluctuations found empirically, the frequency of periodic execution is inappropriate, and as a result of executing calibration more than necessary, color materials and recording media are wasted. May end up.

  Thus, a method is known in which calibration is applied to the patch chart, and color measurement is performed, and the calibration accuracy of the current recording apparatus is determined from the result, thereby determining whether calibration is necessary (for example, , See Patent Document 1). When calibration is performed by such a method, the determination result of the color variation does not depend on the skill of the manager, so that stable calibration can be performed.

JP 2008-60637 A

  However, in the above-described method, it is necessary to check the accuracy by recording and measuring the calibration chart for calculating the calibration correction parameter every time calibration is performed. Then, the accuracy check is more expensive than performing calibration directly.

  The present invention has been made in view of the above points, and provides a determination method and a recording apparatus that can be performed at low cost when determining whether or not calibration execution is necessary without depending on the skill of an administrator.

  Therefore, in the present invention, for a recording apparatus for recording an image on a recording medium, a calibration chart composed of a plurality of patches of a stepwise color tone of each of a plurality of color materials is recorded. A determination method for determining whether or not calibration needs to be performed, wherein the calibration chart includes a setting step for setting a threshold for determining whether or not calibration is performed for recording and measuring the calibration chart. A check chart consisting of a plurality of patches each having a smaller number of patches than the number of patches formed and constituting the calibration chart is recorded, and each patch of the check chart is measured by the colorimetric means. An acquisition process for acquiring colorimetric values by color, and a check chart patch stored in advance A target colorimetric values, a colorimetric value acquired by the acquisition step, on the basis of said threshold value, characterized in that it comprises a necessity determining step of determining the calibration.

  According to the above configuration, whether or not to perform calibration is automatically determined based on the target colorimetric values of the patches constituting the check chart stored in advance and the colorimetric values and threshold values of the recorded check chart. It can be carried out. Thereby, when performing the necessity determination of the calibration execution which does not depend on an administrator's skill, it can carry out at low cost.

It is a block diagram which shows the structure of the color conversion process of embodiment. It is a graph which shows the example of the result of having recorded and measured the color of the patch chart of an embodiment. 3 is a graph showing an example of a Cal LUT created based on the graph shown in FIG. 2. It is a figure which shows the patch chart of embodiment. It is the table | surface which showed the information for recording of embodiment, and the information of target value. It is a block diagram showing an example of an image processing system of an embodiment. 6 is a conceptual diagram illustrating a state in which a color measurement unit 632 is configured in a recording device 627. FIG. It is a conceptual diagram which shows the example of the setting screen of embodiment. It is a flowchart which shows the necessity determination of embodiment.

  Embodiments of the present invention will be described below in detail with reference to the drawings.

  FIG. 1 is a block diagram illustrating a configuration of color conversion processing performed in the image processing system of the embodiment. The inkjet recording apparatus according to the embodiment includes the functions of an RGB recording apparatus that inputs R (red), G (green), and B (blue) signals, and C (cyan), M (magenta), Y (yellow), and K ( Black) has a function of a CMYK recording apparatus for inputting a signal. For the sake of explanation, it is assumed that the image data is composed of 8 bits for each color, and each process is performed with 8 bits for each signal. However, the number of quantizations in the image data and processing of the present invention may be 10 bits, 12 bits, or 16 bits. In addition to the CMYK, the recording apparatus of the embodiment includes Lc (light cyan) in which C is diluted and Lm (light magenta) in which M (magenta) is diluted in addition to CMYK, but R (red). ), G (green), B (blue) Gy (gray), etc., with one or more colors added, or simply C, M, Y or C, M, Y, K only It may be.

  The image signal I / F 101 is an I / F portion of input image data, and here, image data of RGB signals and CMYK signals is input. The input image data includes color matching processing units 102 and 103 that convert device-independent space color data into device-dependent space as shown in the figure, and color separation that converts device-dependent space color data into color material color data. Processing is performed by the processing units 104 and 105 and the gradation correction processing unit 106 that performs gradation correction on the color material color data according to the output color characteristics of the recording apparatus. Each of the color matching processing units 102 and 103 and the color separation processing units 104 and 105 performs a desired color conversion on the input image data by setting a dedicated look-up table (hereinafter also referred to as “LUT”). Can do. This look-up table exists and is managed for each recording mode, for each recording mode such as high-speed recording and low-speed high-quality recording. Of these color conversion processes, the color matching processing units 102 and 103 and the color separation processing units 104 and 105 perform color conversion processing using a 3D-LUT or a 4D-LUT. The gradation correction processing unit 106 performs color conversion processing using a 1D-LUT. The 3D-LUT process is composed of a 3D-LUT table composed of 16 × 16 × 16 = 4096 lattices composed of 16 lattices of 17 count intervals for each color. Since each LUT generation and processing can be executed by a known method, detailed description thereof is omitted here.

  The calibration processing unit 107 corrects the color variation of the recording result caused by the variation of the ejection amount due to the individual difference of the devices, the recording medium, and the color material constituting the apparatus and the change with time. In the calibration processing of the embodiment, a calibration chart, which will be described later with reference to FIG. 4, is recorded and measured in advance by a recording device (hereinafter, also referred to as “reference recording device”) serving as a reference for calibration. Correction processing is performed with the LUT generated from the correspondence between the colorimetric value and the colorimetric value obtained by recording the color of the chart with the target recording device. Here, the colorimetric values are measured using CIE L * a * b * values, and the LUT for recording the calibration chart uses the values of the grid points of the color separation processing units 104 and 105 shown in FIG. Use things. Also, tone patches for each ink color in the check chart, which will be described later with reference to FIG. 4, are recorded using an LUT that uses the values of grid points, as in the calibration chart. Thereafter, the recorded patch part is colorimetrically corrected by applying a 1D-LUT generated so that the color difference between the target colorimetric value stored in advance and the colorimetric value of the target recording device is minimized. I do. For these corrections, different parameters are set for each recording medium or each recording mode.

  FIG. 2 is a graph illustrating an example of a result of recording and measuring a patch chart for generating a calibration processing LUT (hereinafter also referred to as “Cal-LUT”) of the image processing system according to the embodiment. In other words, the calibration chart is recorded in the CIE L * a * b * space with the colorimetric value (Measured) obtained as a result of recording and colorimetry by the target recording device and the target colorimetric value (Target) obtained by the reference recording device. Is plotted. This graph illustrates the state of cyan ink.

  A curve 201 showing the locus of the target colorimetric value by the reference recording device on L * a * b * and a curve 202 showing the locus projected onto the a * b * plane are shown. Further, on L * a * b *, a curve 203 showing the locus of the colorimetric values of the calibration chart in the target recording apparatus and a curve 204 showing the locus projected onto the a * b * plane are shown. Has been. As shown in the figure, the cause of the difference between the target colorimetric value and the colorimetric value of the target recording apparatus is caused by variations in the lot of ink that is a color material, environmental changes in the ink discharge amount, changes with time, and the like.

  In the embodiment, the CIE L * a * b * value of Cyan 70% (data value is 178) has a difference between the target colorimetric value and the colorimetric value, and the color difference is the largest with respect to Cyan 70% of the target colorimetric value. The smaller value indicates that the colorimetric value is 68% (data value is 173).

  FIG. 3 is a graph showing an example of a Cal LUT created based on the graph shown in FIG. By applying this LUT, the output value which was 70% Cyan (data value is 178) in the target recording apparatus is converted to 68% (data value is 173), and the color difference is the smallest Cyan 70% of the target colorimetric value. Output can be done. That is, in the calibration process, the image data value for each color material color is corrected and corrected by the 1D-LUT process so that the colorimetric value closest to the colorimetric value of the target colorimetric value is obtained. In the embodiment, the CIE L * a * b * value is used. However, the density value by a color densitometer that can be read for each RGB signal and the optical density value by a densitometer that handles a monochrome signal are used, and the density difference is minimized. Output may be performed.

  The Cal-LUT of the embodiment needs to be recreated after a certain period of time since the correction purpose includes correction of change over time. (Hereinafter, the generation and regeneration of the Cal-LUT are both referred to as “calibration execution”). In the embodiment, in order to easily and inexpensively determine the re-creation time, a calibration accuracy check created from a part of the calibration chart data used when generating the Cal-LUT (hereinafter also referred to as “Cal check”). The accuracy information is calculated using a check chart.

In addition, the necessity determination of calibration execution according to the embodiment is obtained by the following method.
Colorimetric values measured using the check chart for Cal check L * _Measure , a * _Measure , b * _Measure
Preliminary accuracy target colorimetric values L * _Target , a * _Target , b * _Target
Color difference ΔE = ((L * _Target− L * _Measure ) ² + (a * _Target− a * _Measure ) ² + (b * _Target− b * _Measure ) ² ) ^1/2

  If the color difference ΔE obtained as described above is equal to or greater than a preset threshold value, it is determined that calibration needs to be executed. Note that the determination method is not limited to the color difference calculation formula, and further the method using the color difference based on the CIE L * a * b * values, but another color difference formula is used, or the optical density value of the check chart for Cal check is used. Color measurement may be performed and determination may be made based on the density difference. For example, in a recording system in which there is little variation in color material and recording medium lots, and the cause of the fluctuation is dominated by variation in the discharge amount of the color material ink, the difference in L * value, which is brightness information, not color difference (stored in advance) The difference between the target L * value and the measured colorimetric L * value) may be obtained by comparing with a threshold value. In such a recording system, a colorimeter that can measure the CIE L * a * b * values may not be used. That is, it is obtained by comparing the difference between the colorimetric density value and the pre-stored target density value with a predetermined target density value using a color densitometer based on RGB signals or an optical densitometer capable of measuring the brightness of a monochrome signal. May be.

  FIG. 4 is a diagram illustrating a calibration processing LUT generation patch chart and a calibration execution necessity determination patch chart according to the embodiment. FIG. 4A shows a calibration chart for Cal-LUT generation according to the embodiment, and FIG. 4B shows a check chart for Cal check according to the embodiment. The target colorimetric values of these patches may be associated with each recording medium among a plurality of recording media. Moreover, it may be associated with each recording mode among a plurality of recording modes. That is, each color factor may have a colorimetric value for each possible factor of different color.

  The calibration chart shown in FIG. 4 (a) is composed of a plurality of patches with stepwise colors. That is, it is a patch chart in which the color material colors of the recording apparatus are arranged in 16 gradations for each color. The symbols such as C1 assigned to each patch indicate the color material color and the patch number. The leading C, M, Y, K, c, and m are the color material colors C, M, Y, K, and Lc, respectively. , Lm.

  The check chart shown in FIG. 4B is a Cal check using two patches for each color from the gradation patches for C, M, Y, K, Lc, and Lm in the calibration chart shown in FIG. A patch chart is configured. For this reason, the calibration chart is 96 patches, while the check chart is 12 patches, and the usage amount of the color material and the recording medium is very small compared to the calibration chart. Further, the recording apparatus generally has a recording variation (hereinafter, also simply referred to as “in-plane unevenness”) depending on the position in the recordable area. In the recording apparatus of the embodiment, in-plane unevenness tends to occur in the main scanning direction due to the eccentricity of the motor for scanning the recording head, the vibration of the belt, the shape of the member positioned immediately below the recording medium, and the like. . For this reason, in order to minimize the influence of in-plane unevenness, it is necessary to keep the same position in the main scanning direction. Therefore, the check chart of the embodiment is configured so that each patch of the corresponding calibration chart and the head main scanning position are the same, and the corresponding patch of both patch charts is not affected by in-plane unevenness. Yes.

  FIG. 5 is a table showing information for recording a calibration chart and a check chart used for generating the Cal-LUT according to the embodiment, and information on calibration target values. Such information is prepared for each recording medium or each recording mode. As the information for generating the chart image, the count value of the patch chart and the value of the corresponding color material color signal are shown. For example, the count value of the patch portion of C1 shown in FIG. 4 is (R, G, B) = (0, 0, 0), and the count value of the patch portion of C2 is (R, G, B) = ( 0,0,17). This corresponds to the grid point position of the color separation process 3D-LUT in the color conversion process of FIG.

  Here, an example with RGB signals is shown, but a CMYK signal processing system is also possible by the same method. The color material gradation value indicates the value of the color material color signal in each patch. When the RGB signal value of C1 is input, the color material color signal value is (C, M, Y, K, Lc, Lm) = (245, 0, 0, 0, 0, 0), and the patch of C2 is , (C, M, Y, K, Lc, Lm) = (194, 0, 0, 0, 0, 0). Based on the chart image data and the color material gradation value information, a color separation processing 3D-LUT at the time of calibration chart recording is generated.

  Referring to the color conversion processing unit in FIG. 1 again, in the color matching processing unit 102, a table in which the input and output have the same value is set as a lookup table for calibration chart recording. The grid point data, which is the processing parameter of the 3D-LUT of the color separation processing unit 104, associates the RGB values as the chart image data of each patch with the C, M, Y, K, Lc, and Lm values as the color material gradation values. Parameters are set. That is, data of (R, G, B) = (0, 0, 0) in the patch portion of C1 is processed via the color matching processing unit 102 and the color matching processing unit 102 via the image signal I / F 101. . As a result, (C, M, Y, K, Lc, Lm) = (245, 0, 0, 0, 0, 0) is output. Further, the data of (R, G, B) = (0, 0, 17) in the patch portion of C2 is processed via the color matching processing unit 102 and the color matching processing unit 102 via the image signal I / F 101. . As a result, (C, M, Y, K, Lc, Lm) = (194, 0, 0, 0, 0, 0) is output.

  In addition, the information of FIG. 5 also serves as information for Cal check, and a flag (* mark) indicating that is set in the patch used also for the check chart for Cal check. The target colorimetric values of the respective color material colors for which this flag is set (the target colorimetric values No. 4 and No. 10 in the case of cyan in the embodiment) are used for the Cal check when determining whether or not to execute calibration. Used as information. The color measurement target value is a target value of the color measurement value of each patch recording unit, and is corrected to become the target color measurement value by the 1D-LUT of the calibration correction process, as shown in FIG. Here, the target colorimetric value is an example of a CIE L * a * b * value. In the case of a color densitometer, the target density value of the RGB signal is set. The same effect can be obtained by storing and managing the information of the target density value.

  FIG. 6A is a block diagram illustrating an example of the image processing system according to the embodiment. The image processing system according to the embodiment can measure a CIE L * a * b * value of a recording device 607 serving as a recording device and a recorded patch chart on a personal computer (PC) 601 serving as an information processing device. A color device 612 is connected. The colorimeter is a color densitometer that reads out density values of RGB signals, or an optical densitometer that reads out density values of monochrome signals, in addition to those that read CIE L * a * b * values as colorimetric values. Also good. Each device is connected via a network or an interface such as a USB or a local bus.

  The PC 601 performs processing by various software programs regarding the control of the recording device 607 and the colorimeter 612 as described below. The storage device 605 stores system programs, application software programs, software programs necessary for recording operations, various parameters, and recording target data created on the PC 601. This storage device is represented by a hard disk or a flash ROM. The CPU 603 executes processing in accordance with a program stored in the storage device 605 such as a normal recording or calibration processing LUT generation and calibration execution necessity determination program stored in the storage device 605. The work memory 604 is used as a work area for the processing. The CPU 603 also has a calendar function using a real-time clock, and can determine whether or not calibration execution is necessary. The data input / output device 606 is a portable storage device represented by CD, DVD and USB memory, and a data communication device represented by a LAN card. The data input / output device 606 inputs data to be recorded and outputs patch chart colorimetric values. Used as an interface for inputting reference colorimetric values. The operation unit 602 serving as a user interface (UI) performs processing related to input by the worker and display to the worker regarding the execution of the above-described processing. Processing related to input by the worker and display to the worker includes input devices such as a keyboard and a mouse, and a display device such as a display. The colorimeter 612 can measure the color of the patch part of the patch chart recorded by the recording device 607 in accordance with an instruction from the PC 601, send the color measurement result to the PC 601, and store it in the storage device 605. A recording device 607 includes a data transfer unit 608, a recording device control unit 609, an image processing unit 610, and a recording unit 611, and performs recording using recording data sent from the PC 601.

  Here, the recording data includes image data and image processing parameters such as LUT, mechanical parameters for driving the apparatus, and recording apparatus control data. The data transfer unit 608 extracts image data and image processing parameters from the recording data sent from the PC 601, sends them to the image processing unit 610, and sends mechanical parameters and recording device control data to the recording device control unit 609. The recording device control unit 609 controls the operation of the recording device 607 according to the recording device control data sent from the data transfer unit 608. The image processing unit 610 performs color conversion processing such as color conversion, gradation correction, and calibration using the image data and image processing parameters sent from the data transfer unit 608 as shown in FIG. Thereafter, although not shown, print data for each color material color is generated by halftoning processing, and the result is sent to the printing unit 611. The recording unit 611 records the processing result sent from the image processing unit 610. Since recording can be realized by a known method, detailed description thereof is omitted here.

  FIG. 6B shows a configuration in which the color measuring device 612 is configured as a color measuring unit 632 in the recording device 627 in the image processing apparatus shown in FIG. If the recording involves colorimetry, the recording data transferred from the PC 621 includes control data for the colorimeter and is sent to the recording device control unit 629. The recording device control unit 629 In conjunction with the recording control at 627, the colorimetric control of the colorimeter 632 is performed. The colorimetric values obtained by the colorimeter 632 are stored and managed by transferring the colorimetric results to the storage device 625 of the PC 621 as in FIG.

  FIG. 7 is a conceptual diagram showing a state in which the color measurement unit 632 is configured in the recording device 627. A sensor 704 is mounted on the side of a carriage 703 for ejecting ink and scanning the recording medium 701 left and right to form a patch image 702.

  FIG. 6C shows the image processing apparatus shown in FIG. 6B in which the PC 621 is configured as a calculation unit 641 in the recording apparatus 648. Therefore, the calculation unit 641 also controls the recording device 648 and the color measurement unit 651 in place of the recording device control unit 629 shown in FIG. Further, the data input / output device 646 is implemented by a portable storage device represented by a CD, a DVD, and a USB memory, or a data communication device represented by a LAN card. The data communication device is used as an interface when receiving recording target data such as a document and an image and an execution command for colorimetric value correction parameter calculation processing from another host PC 647. At this time, if the data to be recorded is input via a portable storage device, and the colorimetric value correction parameter calculation processing and the normal recording execution instruction are specified from the UI 642, the processing is completed only by the recording device 648. The host PC 647 is not essential.

  FIG. 8 is a conceptual diagram illustrating an example of a setting screen related to necessity determination of a calibration execution software program that operates on the PC 601 of the embodiment. This setting screen is displayed when an operator operates the UI 602. This setting screen is roughly divided into an accuracy check setting 801 and a schedule setting 802. In the accuracy check setting, a threshold value used for the determination process is set, and in the schedule setting, whether or not the determination process is automatically executed periodically is set. The set values here are managed and stored in the storage device 605 as accuracy check information and schedule management information. In the determination schedule management in the embodiment, the necessity determination process of the calibration execution software program is automatically executed based on this setting. Further, the schedule setting 502 includes a check box 803 that is set so that the calibration processing LUT is automatically regenerated when it is determined that calibration is necessary. When the setting button 805 is pressed, the contents set on the screen are additionally written in the accuracy check information and schedule management information of the storage device 605, and when the cancel button 804 is pressed, the screen is closed without adding the setting contents on the screen. The schedule management information stores and manages calibration check execution, calibration execution history information, result information, and the like in addition to the above-described setting content information.

  FIG. 9 is a flowchart illustrating the necessity determination of the calibration execution software program operating on the PC 601 of the embodiment. This flow operates when the operator manually executes the necessity of calibration execution from the UI 602 or when an automatic execution instruction is issued from the determination schedule management.

  First, the check chart shown in FIG. 4B, which is smaller than the number of patches in the calibration chart shown in FIG. 4A, is generated (step S901). Here, based on the information shown in FIG. 5 stored in the storage device 605 in FIG. 6, the check chart image based on the RGB value of the chart image data corresponding to the recording medium and the flag indicating the Cal check patch Generate data. Then, the generated image data of the check chart is recorded, and the CIE L * a * b * value is measured by the colorimetric processing unit 3 (step S902). The PC 601 generates a lookup table for calibration chart recording based on the RGB value information of the chart image data of FIG. 5 and the distribution value of the color material signal which is the color material gradation value information. Then, the parameters are set as processing parameters in the color matching processing unit 102 and the color separation processing unit 104 shown in FIG. 1 of the image processing unit 710 via the data transfer unit 608 of the recording device 607. At this time, the 1D-LUT of the gradation correction processing unit 106 and the calibration processing unit 107 is set with a parameter that makes the input value and the output value the same value. Next, the check chart data generated in S <b> 901 of the PC 601 is transferred to the recording device 607. In the recording device 607, recording control is performed by the recording device control unit 709 based on control data from the PC 601. The check chart data is subjected to color processing conversion and halftoning processing by the image processing unit 610 via the data transfer unit 608 and is recorded via the recording unit 611. The patch part C4 of the check chart is (C, M, Y, K, Lc, Lm) = (122, 0, 0, 0, 0, 0), and C10 is (C, M, Y, K, Lc, Lm). = A patch having a value of (29, 0, 0, 0, 0, 0) is recorded.

  Here, the recording density of the patch portion in the low density region is selected because it changes sensitively to fluctuations in the ejection amount of the head, for the following reason. The change in the ink color material discharge amount changes the color material dot diameter on the recording medium. A large factor due to the density on the recording medium is the area ratio between the portion where the color material is placed on the recording medium and the portion where it is not. In the high density portion, since the area of the ink color material is almost occupied on the recording medium, the change in the area ratio with respect to the change in the dot diameter is small. On the other hand, in the low density portion, the area occupied by the ink color material is small. For this reason, the variation in the area ratio of the ink color material portion due to the variation in the dot diameter of the ink color material becomes large. Therefore, the density variation with respect to the ink color material ejection variation reacts more sensitively in the low density region than in the high density region. For patches other than C4 and C10, patches having the values described in the color material gradation values in the figure are recorded. After the recording is finished, the colorimeter 612 measures the color of the patch portion in the same manner according to the software program in the PC 601. The CIE L * a * b * values of the twelve types of patches measured by the colorimeter 612 are managed and stored in the storage device 605 of the PC 601.

  Next, the color difference of each patch is calculated by the above-described method from the colorimetric and stored colorimetric values and the colorimetric target values stored in advance in FIG. 5 (step S903). Then, it is determined whether or not calibration execution is necessary based on the calculated color difference between the 12 types of patches and the threshold value based on the accuracy check setting 501 set in FIG. 8 (step S904). Here, if there is even one exceeding the threshold, it is determined that calibration execution is necessary. As a result of this determination, if there is no need to execute calibration, the process proceeds to step S907. The calibration check execution and the history information and result information in the calibration execution are additionally recorded in the schedule management information of the storage device 605 (step S907), and the process ends. On the other hand, if it is necessary to execute calibration, the process advances to step S905. In the embodiment, the determination method in the case where there is one exceeding the threshold value is shown as an example, but the following two methods may be used. The first method is to calculate an average color difference for each color material and compare with a threshold value. That is, the average value of the color difference between the patch portions of C4 and C10 is calculated. Similarly, average color differences of M4 and M10, Y4 and Y10, K4 and K10, c4 and c10, and m4 and m10 are calculated. If even one of these six types of average color differences exceeds the threshold value, it is determined that calibration is necessary, and if not, it is determined that it is not necessary. In the second method, the average value of the color differences of the 12 types of patch portions is compared with a threshold value, and if the threshold value is exceeded, it is determined that calibration is necessary, and if not, it is determined that it is not necessary.

  The setting value of the calibration automatic execution setting 803 in FIG. 8 is acquired (step S905), and if not automatically executed, the process proceeds to S907. The calibration check execution and the history information and result information in the calibration execution are additionally recorded in the schedule management information of the storage device 605 (step S907), and the process ends. On the other hand, in the case of automatic execution, the calibration chart of FIG. 4A is recorded, colorimetric and calibration is performed, and stored and managed as information necessary for calibration (step S906). The calibration check execution and the history information and result information in the calibration execution are additionally recorded in the schedule management information of the storage device 605 (step S907). As described above, according to the embodiment, the necessity of performing calibration can be determined at low cost without depending on the skill of the administrator.

104 Color separation processing unit 106 Gradation correction processing unit 107 Calibration processing unit 610 Image processing unit 612 Colorimeter

Claims (5)

For a recording apparatus that records an image on a recording medium, it is necessary to execute a calibration by recording a calibration chart composed of a plurality of patches of a stepwise color tone of each of a plurality of color materials. A determination method for determining whether or not
A setting step of setting a threshold value for determining whether or not calibration execution is necessary to record and measure the calibration chart;
The calibration chart is configured with a smaller number of patches than the configured number of patches, and a check chart including a plurality of patches including the patches forming the calibration chart is recorded, and the colorimetric unit is used to record the check chart. An acquisition step of measuring each patch to acquire a colorimetric value;
A determination step of determining whether the calibration needs to be performed based on a target colorimetric value of a patch of the check chart stored in advance, the colorimetric value acquired in the acquisition step, and the threshold value; The determination method characterized by this.   The determination method according to claim 1, wherein the target colorimetric value of the patch of the check chart stored in advance is associated with each recording medium among a plurality of recording media.   The determination method according to claim 1, wherein the target colorimetric value of the patch of the check chart stored in advance is associated with each recording mode among a plurality of recording modes.   The check chart is a part of the calibration chart, and accuracy information of gradation correction using the colorimetric values of the calibration chart instead of the colorimetric values of the check chart corresponding to the calibration chart. The determination method according to claim 1, wherein: A recording apparatus that records a calibration chart composed of a plurality of patches of stepwise colors of each of a plurality of color materials and determines whether or not to perform calibration,
Setting means for setting a threshold value for determining whether or not calibration execution is necessary for recording and measuring the calibration chart;
The calibration chart is configured with a smaller number of patches than the configured number of patches, and a check chart including a plurality of patches including the patches forming the calibration chart is recorded, and the colorimetric unit is used to record the check chart. Acquisition means for measuring each patch to acquire a colorimetric value;
A determination unit configured to determine whether the calibration needs to be performed based on a target colorimetric value of a patch of the check chart stored in advance, the colorimetric value acquired by the acquisition unit, and the threshold value; A recording apparatus.

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