Image processing device, image processing method and program

Abstract

To prevent the occurrence of reduction in inspection accuracy of a printed matter due to the occurrence of secular change of a device.SOLUTION: An image processing device comprises: acquisition means which acquires first image data expressing a chart image, second image data expressing an image obtained by reading a first printed matter of an image including the chart image, and third image data expressing an image obtained by reading a second printed material of an image including the chart image; and inspection means which compares the first comparison result between the first image data and the second image data with the second comparison result between the first image data and the third image data, and inspects the second printed matter using an inspection parameter obtained from the result of the comparison.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to an image processing technique for inspecting printed matter output by a printing device. [Background technology]

[0002] There is a need to ensure the quality of printed materials by inspecting the print results after printing. Because visual inspection requires a lot of time and cost, inspection systems that perform inspection automatically have been proposed.

[0003] In such an inspection system, the print result is inspected based on the difference between a reference image that serves as an inspection standard for the printed matter registered in advance and an inspection target image obtained by scanning the printed matter to be inspected, using inspection parameters that have been set in advance in the printing device.

[0004] Regarding the setting of inspection parameters, Patent Document 1 introduces a method of obtaining inspection parameters via the Internet, while Patent Document 2 introduces a method of calculating and setting optimal inspection parameters for each paper type of printed matter to be inspected. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent application No. 2020-84788 [Patent Document 2] Patent Publication No. 2019-184855 Summary of the Invention [Problem to be solved by the invention]

[0006] In the printing device described above, if changes in scanning performance occur over time (for example, deterioration of the scanner's LED over time), the test results before and after the change over time will differ, even if the test parameters used in the test are the same. As a result, a test result that was NG before the change over time may become OK after the change over time. [Means for solving the problem]

[0007] The image processing device according to the present invention includes an acquisition means for acquiring first image data representing a chart image, second image data representing an image obtained by reading a first printed matter of an image including the chart image, and third image data representing an image obtained by reading a second printed matter of an image including the chart image, and an inspection means for comparing a first comparison result between the first image data and the second image data and a second comparison result between the first image data and the third image data, and inspecting the second printed matter using inspection parameters obtained as a result of the comparison. The third image data has changed in image quality over time compared to the first printed matter, the first comparison result is first difference image data between the first image data and the second image data, and the second comparison result is second difference image data between the first image data and the third image data, and the inspection means updates the inspection parameters based on the difference between the first difference image data and the second difference image data, and the inspection means determines whether the number of pixels that are different between the first difference image data and the second difference image data is equal to or less than a threshold, and if the number of pixels is greater than the threshold, updates the inspection parameters. It is characterized by the following. [Effects of the Invention]

[0008] It is possible to prevent a decrease in the inspection accuracy of printed materials due to changes in the device over time. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a configuration diagram of a printing system including an image processing apparatus. [Figure 2] FIG. 2 is a configuration diagram of an image processing apparatus and a printing apparatus according to the first embodiment. [Figure 3] 10 shows an example of a chart image for calculating inspection parameters and its reference data described in Example 1. [Figure 4] 10 is a flowchart of a reference point creation mode for calculating inspection parameters described in the first embodiment. [Figure 5] 10 is a flowchart of an inspection parameter adjustment mode described in the first embodiment. [Figure 6] Examples of test parameters described in Example 1. [Figure 7] 10 shows an example of a chart image and its reference data for calculating inspection parameters described in Example 2. [Figure 8] Examples of test parameters described in Example 2. [Figure 9] FIG. 10 is a configuration diagram of an image processing device and a printing device according to a third embodiment. [Figure 10] 10 is a flowchart for automatically updating the inspection parameters described in Example 3. [Figure 11] 10 is a flowchart for automatically updating the inspection parameters described in Example 3. [Figure 12] 10 is a flowchart of a parameter update part for automatically updating inspection parameters according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, embodiments of the present invention will be described with reference to the drawings. Note that the following embodiments do not limit the present invention, and not all of the combinations of features described in the present embodiments are necessarily essential to the solution of the present invention. Note that the same components will be described with the same reference numerals. Furthermore, each process (step) in the flowchart will be indicated with a reference numeral beginning with S. [Example]

[0011] In the first embodiment, an example in which the inspection parameters of an image processing device that inspects point defects and line defects are automatically updated will be described.

[0012] FIG. 1 shows an example of the overall configuration of a printing system that outputs and inspects printed materials, including an image processing device 100 to which the present invention is applied. The printing system of this embodiment includes the image processing device 100, a printing server 180, and a printing device 190. The printing server 180 has a function of generating a print job for a document to be printed and submitting the print job to the printing device 190. The printing device 190 has a function of forming an image on a recording medium (print paper) based on the print job submitted from the printing server 180. The printing device 190 can be an offset printing device, an electrophotographic device, an inkjet device, or the like. In this embodiment, it is assumed that the printing device is an electrophotographic printing device.

[0013] The printing device 190 has a paper feed unit 191, and the user sets printing paper in advance in the paper feed unit 191. When a print job is input, the printing device 190 transports the printing paper set in the paper feed unit 191 along a transport path 192, forms an image on one or both sides of the paper, and sends it to the image processing device 100.

[0014] The image forming apparatus 100 of the present invention performs an inspection process to check for defects on the paper, i.e., the printed matter, on which the printing device 190 has formed an image and which has been sent via a conveyance path 192. In other words, the image processing apparatus 100 functions as an inspection processing apparatus.

[0015] The image processing device 100 includes a CPU 101, RAM 102, ROM 103, a main memory device 104, and an image reading device 105. It also includes an interface (I / F) 106 with a printing device, a general-purpose interface (I / F) 107, a user interface (UI) panel 108, and a main bus 109. It also includes a conveyance path 110 for printed materials connected to a conveyance path 192 of the printing device 190, an output tray 111 for printed products that have passed inspection, and an output tray 112 for printed products that have failed inspection due to the discovery of defects. It should be noted that printed materials may be classified into more detailed categories than just the two categories of pass and fail. The image reading device 105, the user interface (UI) panel 108, the output tray 111, and the output tray 112 may be provided in a device external to the image processing device 100, such as the printing device 190.

[0016] The CPU 101 is a processor that comprehensively controls each unit within the image processing device 100. The RAM 102 functions as the main memory, work area, etc. of the CPU 101. The ROM 103 stores a group of programs executed by the CPU 101. The main storage device 104 stores applications executed by the CPU 101, data used in image processing, etc.

[0017] An image reading device (scanner) 105 can read one or both sides of a printed material sent from a printing device on a conveyance path 110 and acquire it as image data. A printing device I / F 106 is connected to a printing device 190, and can synchronize the timing of processing printed materials with the printing device 190 and communicate their operating statuses with each other. A general-purpose I / F 107 is a serial bus interface such as USB or IEEE1394, and allows the user to take out data such as logs or import other data into the image processing device 100.

[0018] The UI panel 108 is, for example, a liquid crystal display, and functions as a user interface for the image processing device 100, displaying the current status and settings and informing the user. It also accepts instructions from the user by providing a touch panel or buttons. A main bus 109 connects the various components of the image processing device 100. Although not shown in FIG. 1, various internal components of the image processing device 100 and the printing system can be operated by instructions from the CPU 101. For example, it is possible to synchronize the movement of transport paths, or to switch between sending printed materials to the pass output tray 111 or the fail output tray 112 depending on the inspection results. In addition to the CPU, a GPU may also be provided.

[0019] Overall, the image processing device 100 transports printed materials sent from the printing device 190 along a transport path 110, while performing the inspection process described below based on the image data of the printed materials read by the image reading device 105. If the result of the inspection process shows that the printed materials pass the inspection, they are transported to an acceptable output tray 111, and if not, they are transported to a rejected output tray 112. In this way, only those whose quality has been confirmed can be collected in the output tray 111 as deliverables for delivery.

[0020] 2 shows the functional block configuration of the image processing device 100 and printing device 190 related to the inspection processing of the present invention. The image processing device 100 has an inspection setting management unit 201, a storage device 202, an image reading unit 204, an inspection unit 205, and an inspection parameter calculation unit 206, and the printing device 190 has a printing unit 203.

[0021] Based on a user operation acquired via the UI panel 108, the inspection setting management unit 201 reads a chart image for calculating inspection parameters stored in the storage device 202 and transmits it to the printing unit 203. The inspection setting management unit 201 also transmits the inspection parameters to be used in the inspection process acquired via the UI panel 108 to the inspection unit 205. The storage device 202 is the RAM 102 or the main storage device 104, and the chart image for calculating inspection parameters and its reference image are, for example, the images shown in Fig. 3. Fig. 3 will be described later.

[0022] The printing unit 203 prints a chart image for calculating inspection parameters. The image reading unit 204 reads the printout printed by the printing unit 203 and transmits the read data to the inspection unit 205. The inspection unit 205 acquires a reference image of the chart image for calculating inspection parameters from the storage device 202. Based on the acquired reference image, the inspection unit 205 performs an inspection process on the chart image for calculating inspection parameters received from the image reading unit 205 using the set inspection parameters, and acquires a current inspection result image.

[0023] Here, the inspection process may involve, for example, calculating feature points for each of the reference image and the scanned image, aligning them based on the calculated feature points, finding the difference between the aligned images, and then performing a filter process based on the inspection parameters. The inspection result image is the image after this processing, and is an image in which detected defects in the inspection target image can be identified. Furthermore, the inspection process is not limited to the above method, as long as it can find the difference.

[0024] After the inspection process, the inspection unit 205 transmits the current inspection result image to the inspection parameter calculation unit 206. The inspection parameter calculation unit 206 acquires the inspection result image at the reference time point from the storage device 202. New inspection parameters are calculated based on the inspection result image at the reference time point and the current inspection result image, and are transmitted to the inspection unit 205.

[0025] The inspection parameters are used to adjust the accuracy of the inspection process, and in this embodiment, the contrast value and defect size are used.

[0026] The specified contrast value is the threshold for the difference in contrast value between the pixel of a point defect or line defect detected in the inspection process and the surrounding pixels, and is the threshold at which defects with a contrast value below the specified value will not be judged as unsuccessful for inspection. For example, it is specified by the Y value when the color space of a pixel is converted to the XYZ space.

[0027] The specified defect size is the size of point and line defects to be detected in the inspection process, and is the threshold below which defects below the specified value will not be rejected. For example, the diameter is specified in millimeters on the paper for point defects, and the width and length are specified in millimeters for line defects.

[0028] 3 shows an example of a chart image for calculating inspection parameters and its reference image. The types of defects in this embodiment are point defects and linear defects, and the chart image for calculating inspection parameters depicts point defects and linear defects of multiple sizes against multiple background colors. On the other hand, the reference data in the figure does not depict point defects or linear defects, and shows an example of an image in which the print result is defect-free and non-defective, or in which the image is a reference image for detecting defects from the print result.

[0029] 4 is a flowchart of the advance preparation process that is performed before the occurrence of changes over time. The examination setting management unit 201 receives a user instruction to transition to a mode for creating a reference point for calculating examination parameters from the user (S401).

[0030] The inspection setting management unit 201 reads the chart image for calculating the inspection parameters from the storage unit 202 and transmits it to the printing unit 203 to perform printing processing (S402).

[0031] The image reading unit 204 reads the printed matter printed in the printing process and transmits the scanned data to the inspection unit (S403).

[0032] The inspection unit 205 reads a reference image of a chart image for calculating inspection parameters, which is stored in advance, from the storage unit 202. Using the read reference image as a reference, the inspection unit 205 performs an inspection process to compare the scanned data sent from the image reading unit 204 and obtain differential image data (S404).

[0033] The inspection unit 205 stores the differential image data inspection result image, which is the result of the inspection process, in the storage device 202 as an inspection result image of the reference point (S405).

[0034] 5 is a flowchart of a process for adjusting the inspection parameters so that an inspection equivalent to the reference point can be performed after it is determined that a change over time, i.e., a change in image quality, has occurred, or before an inspection process for a printed material is actually performed. The inspection setting management unit 201 receives an inspection parameter adjustment mode from the user (S501).

[0035] The following steps S502 to S504 are the same as steps S402 to S404 in Fig. 4. The inspection setting management unit 201 reads a chart image for calculating inspection parameters from the storage unit 202, transmits it to the printing unit 203, and performs printing (S502). The image reading unit 204 reads the printed matter printed in the printing process, and transmits the scanned data to the inspection unit (S503). The inspection unit 205 reads a reference image of the chart image for calculating inspection parameters that has been saved in advance from the storage unit 202, and inspects the scanned data sent from the image reading unit 204 using the reference image as a reference (S504).

[0036] Next, the inspection parameter calculation unit 206 compares the current inspection result image data, which is the result of the inspection process by the inspection unit 205, with the inspection result image data of the reference point saved in the storage unit 202 during the reference point creation mode (S505). The comparison method is, for example, a method of finding the difference in pixel values ​​between the inspection result images. Alternatively, a method of comparing a list of objects detected as defects with a list of all objects in the chart image. In other words, it is sufficient to obtain the difference between the current inspection result image and the reference point inspection result image as the comparison result. In other words, the difference between the above-mentioned difference image data for the current time and the reference point is obtained as the comparison result.

[0037] Next, the comparison result is evaluated (S506). For example, the evaluation can be based on the number of pixels that have differences, or the percentage of the list of objects detected as defects that are the same among all the lists of objects in the chart image.

[0038] It is determined whether the evaluation result is equal to or less than a predetermined threshold value that is preset for each evaluation method (S507).

[0039] If the comparison result is greater than the threshold, the inspection parameters of the inspection unit 205 are updated, and the inspection process is repeated from S504 (S508).

[0040] If the evaluation result is equal to or less than the threshold, it is determined that current inspection parameters that can obtain inspection results equivalent to those of the reference point have been found, and the inspection parameters are set in the inspection unit 205 (S509).

[0041] Here, the threshold value in S507 is the number of pixels that is preset when the evaluation method is based on the number of pixels that have a difference. If the inspection result of the reference point and the current inspection result are below this threshold, the inspection results are determined to be equivalent.

[0042] The method for updating the inspection parameters in S508 is to increase or decrease each value by ±1 in units of the current inspection parameters, for example, if the inspection parameters are the contrast value, the diameter size of a point defect, and the width and length of a line defect. If the evaluation result does not fall below the threshold value even after a certain number of repetitions, the inspection parameters that result in the value closest to the threshold value are set. Another example of a change method is to increase or decrease the inspection level shown in Figure 6 by ±1.

[0043] Figure 6 shows an example of inspection parameters that are set in advance in the inspection unit 205. For user convenience, detection levels are defined for point defects and line defects, allowing users to intuitively set inspection parameters using the detection levels. The point defect detection condition, which is one of the line defect parameters, is specified to prevent overdetection of point defects, which may occur depending on the line defect parameter settings.

[0044] As described above, according to the first embodiment, it is possible to automatically update the inspection parameters of the image processing device that inspects point defects and line defects. [Example]

[0045] In Example 2, in addition to Example 1, an example will be described in which inspection parameters are updated so that inspection can be performed taking into account the state in which point defects and linear defects exist near the edge. Hereinafter, explanations of the contents common to Example 1 will be omitted, and only the contents characteristic of Example 2 will be explained.

[0046] FIG. 7 shows an example of a chart image and its reference image for use in calculating inspection parameters used in this embodiment.

[0047] FIG. 8 shows an example of inspection parameters that are set in advance in the inspection unit 205 and that are used in this embodiment.

[0048] The system configuration (FIG. 2) and processing flow (FIGS. 4 and 5) are the same as those in the first embodiment, except that the chart image for calculating the inspection parameters, its reference image, and the definition of the inspection parameters used in the inspection unit 205 are different.

[0049] As described above, according to the second embodiment, inspection can be performed taking into consideration the state in which point defects and linear defects exist near the edge. [Example]

[0050] In the third embodiment, an example will be described in which the inspection parameters of the image processing device are automatically updated while performing printing and inspection processing without accepting the inspection parameter adjustment mode of the first embodiment. Hereinafter, the description of the contents common to the above-mentioned embodiments will be omitted, and only the contents characteristic of the third embodiment will be described.

[0051] 9 shows the functional block configuration of the image processing device 100 and printing device 190 shown in FIG. 1, which are involved in the inspection process of this embodiment. The image processing device 100 has an inspection setting management unit 901, a storage device 902, a chart embedding unit 903, an image reading unit 905, an inspection unit 906, and an inspection parameter calculation unit 907, and the printing device 190 has a printing unit 904.

[0052] The inspection setting management unit 901 reads an inspection target image stored in the storage device 902 and transmits it to the printing unit 904 based on a user operation received via the UI panel 108. It also transmits inspection parameters to be used in the inspection process, received via the UI panel 108, to the inspection unit 906. It also reads a chart image for calculating inspection parameters stored in the storage device 902 and transmits it together with the inspection target image to the chart embedding unit 903. It also transmits the inspection target image with the chart embedded received from the chart embedding unit 903 to the printing unit 904. It also controls the timing of whether or not to generate an inspection target image with the chart embedded in the chart embedding unit 903. The timing is controlled by counting the number of prints and generating an inspection target image with the chart embedded in the chart embedding unit 903 every preset number of times.

[0053] The storage device 902 is the RAM 102 or the main storage device 104, and stores an inspection target image and its reference image, a chart image for calculating inspection parameters and its reference image, and an inspection result image of a reference point. The inspection target image is, for example, the image shown in Fig. 12. The chart image for calculating inspection parameters and its reference image are, for example, the images shown in Fig. 3.

[0054] The chart embedding unit 903 embeds a chart image for calculating inspection parameters in the image to be inspected, and transmits the image to the inspection setting management unit 901 as an inspection image with an embedded chart. The chart is embedded by dividing the chart image and embedding it in a margin area of ​​the image to be inspected. The inspection image with an embedded chart is, for example, the image shown in FIG. 12B. Furthermore, the chart embedding unit 903 embeds the reference image of the chart image for calculating inspection parameters received from the inspection unit 906 in the reference image of the image to be inspected received from the inspection unit 906, and transmits the reference image of the inspection image with an embedded chart to the inspection unit 906. The reference image of the inspection image with an embedded chart is, for example, the image shown in FIG. 12C.

[0055] The printing unit 904 prints the inspection target image and the inspection target image with the chart embedded therein.

[0056] An image reading unit 905 reads the printed matter printed by the printing unit 904 and transmits the read data to an inspection unit 906 .

[0057] The inspection unit 906 acquires a reference image of the image to be inspected and a reference image of the chart image for calculating inspection parameters from the storage device 902. It also acquires a reference image of the image to be inspected with the chart embedded from the chart embedding unit 903. Based on the acquired reference image, the inspection unit 906 performs inspection processing using the set inspection parameters on the image to be inspected and the image to be inspected with the chart embedded received from the image reading unit 905, and calculates an inspection result image. The inspection unit 906 also checks whether an inspection result image of the reference point is saved in the storage device 902. The inspection unit 906 also transmits the inspection result image to the inspection parameter calculation unit 907 as the current inspection result image. After the inspection processing, the inspection unit 906 also transmits the inspection result image to the storage device 902 as the inspection result image of the reference point.

[0058] The inspection parameter calculation unit 907 acquires the inspection result image at the reference time point from the storage device 902. Furthermore, it calculates new inspection parameters based on the acquired inspection result image at the reference time point and the current inspection result image received from the image inspection unit 906, and transmits the new inspection parameters to the inspection unit 906.

[0059] 10 is a flowchart showing the overall process of automatically updating the inspection parameters. The inspection setting management unit 901 receives a print instruction from the user via the UI panel 108 and increments a print count counter stored internally (S1001).

[0060] The print number counter is divided by a preset N and the remainder is determined (S1002).

[0061] If the result of S1002 is 0, the process proceeds to flowchart 11 shown in Fig. 11 (S1003), and after the processing of flowchart 11 is completed, the process returns to S1001. Flowchart 11 shown in Fig. 11 will be described later.

[0062] If the result of S1002 is not 0, normal inspection processing is executed. That is, an inspection target image is obtained from the storage device 902 and sent to the printing unit 904 (S1004).

[0063] Next, the image reading unit 905 reads the printout of the image to be inspected (S1005).

[0064] Next, the inspection unit 906 performs inspection processing on the read image to be inspected using the reference image of the image to be inspected obtained from the storage device 902 (S1006).

[0065] 11 is a flowchart 11 of a parameter update process for automatically updating inspection parameters. The inspection processing management unit 901 reads the image to be inspected and a chart image for calculating inspection parameters from the storage device 902, and transmits them to the chart embedding unit 903. The chart embedding unit 903 embeds the chart for calculating inspection parameters in the image to be inspected, generates a chart-embedded image, and transmits it to the inspection processing management unit 901 (S1101).

[0066] The inspection process management unit 901 transmits the chart-embedded image to the printing unit 904 (S1102). The printing unit 904 prints the chart-embedded image.

[0067] The image reading unit 905 reads the image printed in S1102 (S1103).

[0068] The inspection unit 906 acquires a reference image of the image to be inspected and a reference image of the chart image for calculating inspection parameters from the storage device 902. Then, it transmits the acquired reference image of the image to be inspected and the reference image of the chart image for calculating inspection parameters to the chart embedding unit 903. The chart embedding unit 903 generates a reference image of the image to be inspected with the chart embedded and transmits it to the inspection unit 906. The inspection unit 906 inspects the image to be inspected read by the image reading unit 905 using the reference image of the image to be inspected with the chart embedded as a reference (S1104). Note that the process of generating the reference image of the image to be inspected with the chart embedded described above may be executed in any step between S1101 and S1104.

[0069] The inspection unit 906 checks whether the inspection result image of the reference point is stored in the storage device 902 (S1105). If it is not stored, the inspection result image is stored in the storage device 902 as the inspection result image of the reference point (S1111), and this flowchart ends.

[0070] If it has been saved, the inspection result of 1104 is compared with the inspection result image of the reference point (S1106).

[0071] The comparison result is evaluated (S1107), and it is determined whether the evaluation result is equal to or less than the threshold value (S1108).

[0072] If the evaluation result is greater than the threshold, the inspection parameters are updated (S1109). Once the inspection parameters are updated, the inspection process S1104 is executed again.

[0073] If the evaluation result is equal to or less than the threshold, the inspection parameters used in S1104 are set as new inspection parameters and registered in the inspection unit 906 (S1110). Note that the comparison method and evaluation method are, for example, the methods described above in the first embodiment, but are not limited to these.

[0074] The inspection unit 906 stores the inspection result image in the storage device 902 as the reference point inspection result image (S1111) and ends the process.

[0075] As described above, according to the third embodiment, the inspection parameters of the image processing apparatus can be automatically updated while performing the printing and inspection processes without accepting the inspection parameter adjustment mode.

[0076] Further, the present invention can also be realized by supplying a program that realizes one or more functions of the above-described embodiment to a system or apparatus via a network or a storage medium, and having one or more processors in a computer of the system or apparatus read and execute the program. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

Explanation of Signs

[0077] 100 Image processing apparatus 201 Inspection setting management unit 202 Storage device 204 Image reading unit 205 Inspection unit 206 Inspection parameter calculation unit

Claims

1. an acquisition means for acquiring first image data representing a chart image, second image data representing an image obtained by reading a first printout of an image including the chart image, and third image data representing an image obtained by reading a second printout of an image including the chart image; an inspection means for comparing a first comparison result between the first image data and the second image data with a second comparison result between the first image data and the third image data, and inspecting the second printed matter using inspection parameters obtained as a result of the comparison; and the third image data has image quality that has changed over time compared to the first print, the first comparison result is first difference image data between the first image data and the second image data; the second comparison result is second difference image data between the first image data and the third image data, the inspection means updates the inspection parameters based on the difference between the first subtraction image data and the second subtraction image data; The image processing device is characterized in that the inspection means determines whether the number of pixels that differ between the first difference image data and the second difference image data is less than a threshold value, and if the number of pixels is greater than the threshold value, updates the inspection parameters.

2. The image processing apparatus according to claim 1 , wherein the first printed matter includes at least one of a linear defect and a point defect.

3. 3. The image processing apparatus according to claim 2, wherein the linear defect and the point defect are located near an edge.

4. 4. The image processing apparatus according to claim 1, wherein the image including the chart image is an image generated by embedding the chart image for calculating inspection parameters in an image to be inspected.

5. An acquisition means for acquiring first image data representing a chart image, second image data representing an image obtained by reading a first printout of an image including the chart image, and third image data representing an image obtained by reading a second printout of an image including the chart image; an inspection means for comparing a first comparison result between the first image data and the second image data with a second comparison result between the first image data and the third image data, and inspecting the second printed matter using inspection parameters obtained as a result of the comparison; and the third image data has image quality that has changed over time compared to the first print, the first comparison result is first difference image data between the first image data and the second image data; the second comparison result is second difference image data between the first image data and the third image data, The image processing apparatus according to claim 1, wherein the inspection means updates the inspection parameters based on whether the defect represented by the first differential image data and the defect represented by the second differential image data are the same.

6. 2. The image processing apparatus according to claim 1, wherein the inspection parameter is at least one of a defect detection level, a contrast threshold, and a defect size.

7. 2. The image processing apparatus according to claim 1, wherein the inspection parameters are set for each of a linear defect and a point defect.

8. 2. The image processing apparatus according to claim 1, wherein the inspection parameters for detecting a linear defect include a detection condition for suppressing overdetection of a point defect.

9. A program for causing a computer to function as each of the means of the image processing device according to any one of claims 1 to 8.

10. an acquiring step of acquiring first image data representing a chart image, second image data representing an image obtained by reading a first printout of an image including the chart image, and third image data representing an image obtained by reading a second printout of an image including the chart image; an inspection step of comparing a first comparison result between the first image data and the second image data with a second comparison result between the first image data and the third image data, and inspecting the second printed matter using inspection parameters obtained as a result of the comparison; and the third image data has image quality that has changed over time compared to the first print, the first comparison result is first difference image data between the first image data and the second image data; the second comparison result is second difference image data between the first image data and the third image data, The inspection step updates the inspection parameters based on a difference between the first subtraction image data and the second subtraction image data, The image processing method is characterized in that the inspection process determines whether the number of pixels that differ between the first difference image data and the second difference image data is less than a threshold, and if the number of pixels is greater than the threshold, updates the inspection parameters.

Images