Image inspection system and image inspection device

Abstract

To provide an image inspection system which can accurately execute an image inspection while reducing the standby time of a user.SOLUTION: An image formation device forms a print image corresponding to an original image on a sheet. An image acquisition device acquires an inspection image corresponding to the print image by reading the sheet. Storage means stores in advance correction data for correcting the distortion of the inspection image to the print image generated in the image acquisition device. Correction means corrects the inspection image based on the correction data. Inspection means inspects the printing quality of the print image based on the original image and the corrected inspection image. A sheet conveyance device which is connected to the upstream side or downstream side of the image acquisition device in the sheet conveyance direction may be changed. In this case, update means updates the correction data.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to an image inspection system and an image inspection apparatus for inspecting an image formed on a sheet by an image forming apparatus.

Background Art

[0002] Conventionally, there is known a system in which an inspection apparatus connected to an image forming apparatus that forms an image on a sheet reads an image on the sheet conveyed from the image forming apparatus and inspects the image on the sheet based on the read image. In Patent Document 1, the quality (print quality) of the image formed on the sheet is inspected by comparing a RIP image with an image obtained by reading an image formed on the sheet based on the RIP image. RIP is an abbreviation for raster image processing.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] A system for reading an image of a conveyed sheet includes a first conveyance unit that conveys the sheet when the image of the sheet is being read, and a second conveyance unit that transfers the sheet to the first conveyance unit. When the motor that drives the first conveyance unit is a different motor from the motor that drives the second conveyance unit, the speed at which the sheet is conveyed may vary during image reading. That is, the conveyance speed of the sheet may vary while the inspection apparatus is reading the image, and the image representing the reading result (read image) may stretch or shrink in a direction corresponding to the conveyance direction of the sheet. If the print quality is inspected based on a comparison between such a read image and a RIP image, the inspection accuracy may decrease. [Means for solving the problem]

[0005] The present invention, for example, An image forming system, An image forming unit that forms an image on a sheet corresponding to the first image data input to the image forming system, A first transport unit that transports the sheet transported from the image forming unit, A first motor that drives the first transport unit, A second transport unit that transports the sheet transported from the first transport unit, A second motor that drives the second transport unit, A reading unit that reads the image on the sheet being transported by the second transport unit, It has a processor, The aforementioned processor, The reading unit generates a second image data representing the result of reading the image on the sheet. The second image data is corrected using correction data, where the correction data is data obtained based on image data obtained by the reading unit reading a predetermined image formed on a sheet by the image forming unit, and image data corresponding to the predetermined image. The image formed on the sheet based on the first image data is inspected based on the corrected second image data and the first image data. The present invention provides an image forming system configured in such a manner. [Effects of the Invention]

[0006] According to the present invention, it is possible to provide an image forming system that can perform image inspections with high accuracy while reducing the user's waiting time. [Brief explanation of the drawing]

[0007] [Figure 1] Diagram illustrating the image formation system. [Figure 2] Diagram explaining the controller [Figure 3] A diagram showing an example of a profile. [Figure 4] Diagram illustrating the test image. [Figure 5] A flowchart showing how to create a correction profile. [Figure 6] Diagram illustrating the image formation system. [Figure 7] A flowchart showing how to create a correction profile. [Figure 8] Diagram explaining management information [Modes for carrying out the invention]

[0008] The embodiments will be described in detail below with reference to the attached drawings. Note that the following embodiments do not limit the invention as defined in the claims. While the embodiments describe multiple features, not all of these features are essential to the invention, and the features may be combined in any way. Furthermore, in the attached drawings, identical or similar configurations are given the same reference numerals, and redundant descriptions are omitted.

[0009] [First Embodiment] <Image Forming System (Image Inspection System)> As shown in Figure 1, the image forming system 100 includes an image inspection device 110 and a sheet transport device (image forming device 120, post-processing device 130). In the transport direction of the sheet P, the image forming device 120 is connected to the upstream side of the image inspection device 110, and the post-processing device 130 is connected to the downstream side of the image inspection device 110. That is, the housing 52 of the image forming device 120 and the housing 53 of the post-processing device 130 are different from the housing 51 of the image inspection device 110.

[0010] The image forming apparatus 120 forms an image on the sheet P using an electrophotographic method. Alternatively, the image forming apparatus 120 may use other image forming methods, such as an inkjet method, to form the image.

[0011] The image forming units 20a, 20b, 20c, and 20d respectively form toner images of yellow "Y", magenta "M", cyan "C", and black "K". In the following, the same reference numerals are assigned to a plurality of identical or similar components. When distinguishing a plurality of components, an alphabet is added to the end of the reference numeral. When common matters are described for a plurality of components, the alphabet at the end of the reference numeral is omitted.

[0012] The photosensitive drum 21 is an image carrier that carries an electrostatic latent image and a toner image. The charger 22 charges the surface of the photosensitive drum 21. The exposure device 23 irradiates the surface of the photosensitive drum 21 with laser light corresponding to an image signal to form an electrostatic latent image. The developing device 24 develops the electrostatic latent image using toner to form a toner image. The primary transfer roller 25 transfers the toner image from the photosensitive drum 21 to the intermediate transfer belt 27. The intermediate transfer belt 27 conveys the toner image to the secondary transfer device 28.

[0013] The feeding device 1 feeds the sheet P held in the sheet storage to the conveyance path. The conveyance device 2 conveys the sheet P to the registration device 3. The registration device 3 corrects the skew of the sheet P and conveys the sheet P to the secondary transfer device 28.

[0014] The secondary transfer device 28 transfers the toner image from the intermediate transfer belt 27 to the sheet P. The fixing device 29 applies heat and pressure to the toner image and the sheet P to fix the toner image on the sheet P. The paper discharge conveyance device 4 conveys and discharges the sheet P with the toner image fixed thereon to the outside of the image forming apparatus 120. In FIG. 1, the sheet P is conveyed to the image inspection device 110.

[0015] The image inspection device 110 is an image reading device that reads a sheet P that has an image formed on it by the image forming device 120 and has been discharged from the image forming device 120, and acquires a read image (inspection image). When the sheet sensor 17a detects the leading edge of the sheet P, the entrance roller 15 rotates to pull the sheet P from the image forming device 120 to the image inspection device 110. The entrance roller 15, upper backing roller 13, lower backing roller 14, and exit roller 16 also rotate to transport the sheet P. The image reading unit 11a includes an image sensor and an illumination device that read the first surface of the sheet P. The image reading unit 11b includes an image sensor and an illumination device that read the second surface of the sheet P. The upper backing roller 13 regulates the passage position of the sheet P so that the distance between the image reading unit 11a and the sheet P is maintained within a predetermined range. The lower backing roller 14 regulates the passage position of the sheet P so that the distance between the image reading unit 11b and the sheet P is maintained within a predetermined range. When the sheet sensor 17b detects the rear end of the sheet P, the inlet roller 15, upper backing roller 13, lower backing roller 14, and outlet roller 16 stop rotating. In this embodiment, the motor M1 that drives the transport roller 4a is a different motor from the motor M2 that drives the inlet roller 15. The transport roller 4a is a transport unit included in the paper discharge transport device 4.

[0016] In Figure 1, a post-processing device 130 is connected downstream of the image inspection device 110. The conveying device 30 conveys the sheet P using a plurality of conveying rollers 31, and switches the conveying path of the sheet P using path switching mechanisms 32a and 32b to discharge the sheet P into one of the discharge trays 34a, 34b, or 34c. For example, sheet P that passes the image inspection may be discharged into discharge tray 34b, and sheet P that fails the image inspection may be discharged into discharge tray 34a.

[0017] <Control Configuration> Figure 2 illustrates the control configuration of the image forming system 100. Note that the functions described below only need to be implemented by at least one processor.

[0018] As shown in Figure 2, the image forming system 100 includes an external controller 200, internal controllers 210a, 210b, and 210c, and an operation unit 260. The external controller 200 and the internal controller 210a are connected via an image communication line 222a to a serial communication line 221a. The external controller 200 and the internal controller 210b are connected via an image communication line 222b to a serial communication line 221b. The external controller 200 and the internal controller 210c are connected via a serial communication line 221c.

[0019] The external controller 200 is a control circuit that comprehensively controls the entire image forming system 100. The CPU 201 of the external controller 200 implements various functions according to the control program stored in the ROM (read-only memory) area of ​​the memory 202. The memory 202 may include RAM (random access memory), HDD (hard disk drive), SSD (solid state drive), etc. The external controller 200 may be located inside any of the image inspection apparatus 110, image forming apparatus 120, or post-processing apparatus 130.

[0020] The external controller 200 performs predetermined processing on image data corresponding to an image (e.g., RIP image) received from a device located outside the image forming system 100 (such as a PC, smartphone, or tablet terminal), and outputs the processed image data to the internal controller 210b via the image communication line 222b.

[0021] The internal controller 210b is a controller that controls the image forming apparatus 120. The internal controller 210b may be located inside the image forming apparatus 120. The memory 212a may include ROM, RAM, HDD, SSD, etc. Based on instructions from the external controller 200, the CPU 211b controls the feed device 1, transport device 2, registration device 3, image forming unit 20, fuser 29, paper discharge transport device 4, etc., according to the control program stored in the ROM area of ​​the memory 212b. The CPU 211a controls the image forming apparatus 120 to form an image on the sheet P corresponding to the image data received from the external controller 200.

[0022] The internal controller 210a is a controller that controls the image inspection device 110. The internal controller 210a may be located inside the image inspection device 110. The CPU 211a of the internal controller 210a performs various functions according to the control program stored in the ROM area of ​​the memory 212a. For example, the CPU 211a determines the position of the sheet P based on the detection results of the sheet sensors 17a and 17b. Furthermore, the CPU 211a controls the motor M2 to drive the inlet roller 15, the upper backing roller 13, the lower backing roller 14, and the outlet roller 16. Furthermore, the CPU 211a controls the image reading units 11a and 11b to acquire inspection images of the sheet P. The memory 212a may include RAM, HDD, SSD, etc. The CPU 211a transmits the image data of the inspection image to the external controller 200 via the image communication line 222a. The external controller 200 corrects the image data of the inspection image received from the CPU 211a using a correction profile described later. The external controller 200 performs image inspection based on the corrected image data and the image data of the image (e.g., RIP image) received from an external device of the image forming system 100 as the ground truth image. The CPU 211a receives image reading commands and image inspection commands, etc., from the external controller 200 via the serial communication line 221a.

[0023] Image inspection is performed as follows. For example, the inspection content may be "positional misalignment." The CPU 201 may determine that it is a pass if the amount of misalignment between the position of the correct image and the position of the inspection image is less than or equal to the judgment threshold. The CPU 201 may determine that it is a fail if the amount of misalignment exceeds the judgment threshold. In addition, the inspection content may be set to "black spots." The CPU 201 may determine that it is a pass if the size (e.g., area) of a black spot that is not present in the correct image but is present in the inspection image is less than or equal to the judgment threshold. The CPU 201 may determine that it is a fail if the size of the black spot exceeds the judgment threshold. In this embodiment, "positional misalignment" and "black spots" are described as inspection content, but these are merely examples. In this embodiment, when the inspection content is "positional misalignment," the relative position between the correct image and the inspection image is inspected, but this is merely an example. For example, the absolute position of the inspection image relative to the edge of sheet P may be inspected. In this case, if the distance between the absolute position of the correct image and the absolute position of the inspection image is less than or equal to the judgment threshold, it is determined to be a pass. If the distance exceeds the threshold, it will be judged as a failure.

[0024] The internal controller 210c is a controller that controls the post-processing unit 130. The internal controller 210c may be located inside the post-processing unit 130. The memory 212c may include ROM, RAM, HDD, SSD, etc. The CPU 211c controls the transport rollers 31 and the path switching mechanisms 32a and 32b according to the control program stored in the ROM area of ​​the memory 212c. The CPU 211c receives switching commands for the path switching mechanisms 32a and 32b from the external controller 200 via the serial communication line 221c.

[0025] Here, the communication method between the external controller 200 and the internal controllers 210a, 210b, and 210c is merely an example. The communication method between them may also be the CAN (Controller Area Network) method. Furthermore, the external controller 200 and the internal controllers 210a, 210b, and 210c may be connected by wire or by wireless connection.

[0026] The configuration for reading an image of a conveyed sheet includes a first conveying unit (e.g., entrance roller 15) that conveys the sheet P while the image of the sheet P is being read, and a second conveying unit (conveying roller 4a) that receives the sheet from the first conveying unit. If the motor that drives the first conveying unit (e.g., motor M2) is different from the motor that drives the second conveying unit (e.g., motor M1), the speed at which the sheet is conveyed may fluctuate during image reading. For example, if the housing 51 of the image inspection device 110 is different from the housing 52 of the image forming device 120, the motor that drives the first conveying unit is different from the motor that drives the second conveying unit. As a result, the conveying speed of the sheet P may fluctuate while the image inspection device 110 is reading the image, and the image representing the reading result (read image) may stretch or shrink in the direction corresponding to the conveying direction in which the sheet P is conveyed.

[0027] Figure 3 shows the variation (profile 501) of the scanned image. The vertical axis in Figure 3 represents the amount of image stretching. The horizontal axis in Figure 3 represents the position of the image in the sub-scanning direction. Note that "+" on the vertical axis corresponds to the image stretching in the sub-scanning direction, and "-" on the vertical axis corresponds to the image shrinking in the sub-scanning direction.

[0028] As shown in Figure 3, the image periodically expands and contracts in the sub-scanning direction depending on its position in that direction. This is due to eccentricity of the transport rollers. Also, as shown in Figure 3, the image expands and contracts suddenly in the sub-scanning direction. This is because the transport speed of the sheet when the image forming apparatus 120 discharges the sheet is different from the transport speed of the sheet when the image inspection apparatus 110 receives and transports the sheet. The expansion and contraction of the image may also be caused by the shock generated when the sheet P slips out of the pair of rollers of the image forming apparatus 120 that are holding the sheet P. The sub-scanning direction corresponds to the transport direction in which the sheet is transported.

[0029] Thus, in a configuration where the sheet is transported from an image forming apparatus 120, which has a different housing from the image inspection apparatus 110, there is a possibility that the read image may be stretched or compressed. If the print quality is inspected based on a comparison of such a read image with a correct image (e.g., RIP image), the inspection accuracy may decrease. Therefore, in this embodiment, the following configuration is applied to suppress the decrease in inspection accuracy.

[0030] A correction profile may be created by reversing the sign of profile 501 shown in Figure 3; therefore, profile 501 may be used as a correction profile.

[0031] <Creating a Correction Profile> Figure 4 shows a sheet P (test chart, also called a predetermined image) on which a test image 400 is formed. The test image 400 includes a predetermined reference pattern. The image inspection device 110 reads the image printed on sheet P and generates a read image (inspection image). The predetermined reference pattern allows the image inspection device 110 to detect distortions occurring in the read image (inspection image). For example, such a reference pattern may include a pattern containing multiple horizontal lines arranged at predetermined intervals (a line pattern).

[0032] For example, when a predetermined instruction is input by the user via the operation unit 260, the CPU 201 transmits the image data of the test image 400 and a print command to the internal controller 210b. The predetermined instruction is an instruction indicating the creation of a correction profile (an instruction indicating the formation of a test chart). The image data of the test image 400 may be stored in the ROM area of ​​the memory 202. The CPU 211b generates an image signal corresponding to the image data and outputs the image signal to the exposure unit 23. Furthermore, the CPU 211b controls the image forming apparatus 120 to form the test image 400 on the sheet P.

[0033] Furthermore, when a predetermined instruction is input by the user via the operation unit 260, the CPU 201 controls the internal controller 210a to read the sheet P on which the test image 400 is formed. The CPU 211a of the internal controller 210a reads the sheet P on which the test image 400 is formed according to the read command sent from the CPU 201 and sends the read result (image data) to the CPU 201.

[0034] The CPU 201 creates a correction profile based on the reading results of the test image 400. For example, the CPU 201 calculates the amount of positional displacement in the sub-scan direction of the image representing the reading results of the test image 400 (inspection image) relative to the test image 400, based on the difference between the reading results of the test image 400 and the original data of the test image 400. The amount of displacement corresponds to the value on the vertical axis shown in Figure 3, for example.

[0035] The CPU 201 creates a correction profile to reduce the calculated deviation. For example, the CPU 201 stores in memory 202 a value that has the opposite sign to the vertical axis value shown in Figure 3, associating it with the position in the sub-scan direction.

[0036] When a printed image is to be inspected, CPU201 corrects the image data corresponding to the inspection image using the correction profile described above, and performs the inspection based on the corrected image data and the image data of the correct image.

[0037] Figure 5 is a flowchart showing how the external controller 200 creates a correction profile in this embodiment. The processing shown in the flowchart in Figure 5 is executed by the CPU 201 of the external controller 200.

[0038] In S101, the CPU 201 determines whether an instruction to create a correction profile has been input via the operation unit 260. If such an instruction has been input, the CPU 201 proceeds to S102.

[0039] In step S102, the CPU 201 prints a test image. For example, the CPU 201 sends the image data of the test image 400 and the print command to the internal controller 210b. The CPU 211b generates an image signal corresponding to the image data and outputs it to the exposure unit 23. Furthermore, the CPU 211b controls the image forming apparatus 120 to form the test image 400 on the sheet P. The instruction to create a correction profile may also be input from an external device (PC, smartphone, tablet, etc.) of the image forming system 100.

[0040] In S103, the CPU 201 obtains the result of reading the test image. For example, the CPU 201 controls the internal controller 210a to read the sheet P on which the test image 400 is formed. The CPU 211a of the internal controller 210a reads the sheet P on which the test image 400 is formed according to the read command sent from the CPU 201 and sends the read result (image data) to the CPU 201.

[0041] In S104, CPU201 creates a correction profile based on the reading results of test image 400 using the method described above.

[0042] CPU201 performs image inspection based on image data corrected using a correction profile and image data of the ground truth image.

[0043] As described above, in this embodiment, when an instruction to create a correction profile is input, a test image 400 is formed on sheet P, and the test image is read by the image inspection device 110. The CPU 201 creates a correction profile in the manner described above based on the reading result of the test image 400. When performing image inspection, the external controller 200 corrects the image data acquired from the image inspection device 110 using the correction profile. As a result, stretching and shrinking that occurs in the read image is reduced. This stretching and shrinking is due to the fact that the transport speed of sheet P when the image forming apparatus 120 discharges sheet P is different from the transport speed of sheet P when the image inspection device 110 receives and transports sheet P. Image inspection is performed by comparing the corrected image data with the image data of the correct image. As a result, it is possible to suppress a decrease in the accuracy of print quality inspection.

[0044] Image inspection may be performed in the internal controller 210a. In this case, the CPU 211a receives image data of the correct image from the external controller 200 via the image communication line 222a. The CPU 211a corrects the image data of the inspection image using a correction profile described later. Then, the CPU 211a performs image inspection based on the corrected image data and the received image data of the correct image. Thus, image inspection may be performed in the external controller 200 or in the internal controller 210a.

[0045] In this embodiment, the image data corresponding to the inspection image is corrected by a correction profile, and the inspection is performed based on the corrected image data and the image data corresponding to the ground truth image. However, this is only one example. For example, the image data corresponding to the ground truth image may be corrected by a correction profile, and the inspection may be performed based on the corrected image data and the image data corresponding to the inspection image.

[0046] This embodiment is applicable even if the configuration of the image inspection device 110 is included in the image forming device 120 (i.e., the image reading units 11a and 11b are provided in the image forming device 120). In other words, the motor M1 that drives the transport roller 4a, which is a transport unit included in the paper discharge transport device 4, and the motor M2 that drives the inlet roller 15 may be different. When multiple motors are used, the image stretching and shrinking described above may occur. Therefore, by applying this embodiment, the image data is appropriately corrected, and the accuracy of image inspection is improved.

[0047] [Second Embodiment] The configuration of the image forming system 100 in the second embodiment is substantially the same as that described in the first embodiment. Therefore, the description of the common parts will be omitted.

[0048] In the image forming system 100, for example, an inserter device may be provided between the image inspection device 110 and the image forming device 120. As shown in Figure 6, in the image forming system 100, for example, a large-capacity stacking device (hereinafter referred to as a stacker 140) may be provided between the image inspection device 110 and the post-processing device 130. The stacker 140 has a housing 54, transport sections 40a and 40b, an upper tray 45, and a large-capacity tray 43. The transport section 40a has a plurality of transport rollers 41 and path switching mechanisms 42a and 42b. The path switching mechanism 42a can guide the sheet P to the large-capacity tray 43. The path switching mechanism 42b guides the sheet P that was not guided to the large-capacity tray 43 to the upper tray 45 or the transport section 40b. The transport section 40b guides the sheet P to the post-processing device 130.

[0049] For example, the device connected upstream of the image inspection device 110 when an instruction to create a correction profile is input may be the same as the device connected upstream of the image inspection device 110 when the correction profile was last created. In this case, the degree of stretching and shrinking of the image shown in Figure 3 will not change much, or the change will be small. In such a state, the correction profile created last time can be used. Nevertheless, when an instruction to create a correction profile is input, a test image 400 will be formed on sheet P. That is, sheet P may be wasted (waste paper will be generated). On the other hand, if the upstream or downstream device of the image inspection device 110 is changed, the fluctuation trend shown in Figure 3 will change. Therefore, this embodiment suppresses the generation of waste paper while suppressing a decrease in the inspection accuracy of print quality through the following configuration.

[0050] Figure 7 is a flowchart showing how the external controller 200 creates a correction profile in this embodiment. The processing shown in the flowchart in Figure 7 is executed by the CPU 201 of the external controller 200.

[0051] In S201, the CPU 201 determines whether an instruction to create a correction profile has been input via the operation unit 260. If such an instruction has been input, the CPU 201 proceeds to S202.

[0052] In S202, the CPU 201 detects the combination of devices connected to the image inspection device 110 and determines whether the combination has changed. For example, the CPU 201 may sequentially query the image inspection device 110, the image forming apparatus 120, and the post-processing device 130 for identification information or connection position information via serial communication lines 221a, 221b, and 221c. Alternatively, the CPU 201 may identify which device is connected to which position by sequentially sending query signals to the devices located upstream in the transport direction of the sheet P and obtaining identification information. Alternatively, each device may be provided with a sensor that recognizes the device connected upstream and a sensor that recognizes the device connected downstream. The CPU 201 causes each device to report its own identification information, the identification information of the upstream device, and the identification information of the downstream device. In this case, the image forming apparatus 120 reports its own identification information and the identification information of the image inspection device 110. The image inspection device 110 reports identification information for the image forming apparatus 120, identification information for the image inspection device 110, and identification information for the post-processing device 130. The post-processing device 130 reports identification information for the post-processing device 130 and identification information for the image inspection device 110. Devices that report two pieces of identification information are either the upstream or downstream devices in the image forming system 100. Devices that report three pieces of identification information are connected to both the upstream and downstream devices. According to this resolution rule, the CPU 201 can identify the connection location of each device.

[0053] For example, the ROM area of ​​memory 202 may store management information indicating the combination of devices detected when the previous correction profile was created. The CPU 201 may determine whether the combination of devices connected to the image inspection device 110 has changed by comparing the combination detected this time with the combination stored in memory 202. If the combination has changed, the CPU 201 proceeds to S203. If the combination has not changed, the CPU 201 terminates the processing of this flowchart. Note that if the previous combination is not stored in memory 202, or if the profile is not stored in memory 202, the CPU 201 also proceeds to S203. This is because these cases are equivalent to the combination being changed.

[0054] In step S203, the CPU 201 prints the test image 400. For example, the CPU 201 sends the image data of the test image 400 and a print command to the internal controller 210b. The CPU 211b generates an image signal corresponding to the image data and outputs it to the exposure unit 23. Furthermore, the CPU 211b controls the image forming apparatus 120 to form the test image 400 on the sheet P. The instruction to create a correction profile may also be input from an external device (PC, smartphone, tablet, etc.) of the image forming system 100.

[0055] In S204, CPU201 controls internal controller210a to read sheet P on which the test image 400 is formed. CPU211a of internal controller210a reads sheet P on which the test image 400 is formed according to the read command sent from CPU201 and sends the read result (image data) to CPU201.

[0056] In S205, the CPU201 updates or creates a new correction profile based on the reading results of the test image 400 in the manner described in the first embodiment.

[0057] The correction profile may be the same as profile 501 shown in Figure 3, but with the sign reversed. Therefore, profile 501 may be used as the correction profile.

[0058] In this embodiment, the CPU 201 stores management information in the memory 202 for managing the relationship between the profile 501 and the combination of devices connected to the image inspection device 110. Figure 8(A) shows an example of the management information. In this example, the upstream device i stores "Printer A," which is the identification information of the image forming apparatus 120. In this embodiment, since the image inspection device 110 is directly connected to the image forming apparatus 120, there is no upstream device ii. Similarly, there is no downstream device ii. The downstream device i stores "Post-processing device," which is the identification information of the post-processing device 130. The identification information does not have to be a name; it may be a combination of numbers, a combination of numbers and letters, etc.

[0059] There is an advantage to storing the management information 600 in memory 202. For example, even if the current combination is different from the previous combination, it may match the combination from two combinations ago. In this case, the CPU 201 can skip updating profile 501. In other words, if profile 501 associated with the current combination has already been acquired, the update of profile 501 is skipped. This reduces user waiting time.

[0060] As described above, when an instruction to create a correction profile is entered, the device connected to the image inspection device 110 (the current device) may be the same as the device connected to the image inspection device 110 when the correction profile was last created (the previous device). In this case, the creation of the correction profile is not performed. That is, the correction profile created last time is used for image inspection. Since the creation of the correction profile is skipped, the user's waiting time is reduced.

[0061] On the other hand, the current equipment may differ from the previous equipment. In this case, a correction profile will be created.

[0062] As a result, it becomes possible to suppress the generation of waste paper while also suppressing a decrease in the accuracy of print quality inspection.

[0063] If the current device is the same as the previous device, a notification may be displayed on the display panel on the operation unit 260 indicating that the creation of a correction profile will not be performed. This allows the user to know that the creation of a correction profile will not be performed. If the test chart is not printed despite the user instructing the system to create a correction profile, the user may mistakenly believe that the image forming system 100 has malfunctioned. In this embodiment, the user is notified that the creation of a correction profile will not be performed, thus preventing the user from making such a mistake.

[0064] <Examples of other combinations> Figure 8(B) shows that the combination profile 501 shown in Figure 6 has been newly added to the management information 600. The combination profile 501 shown in Figure 6 is assigned the profile number PF2. This makes it distinguishable from the combination profile 501 shown in Figure 1, which has the profile number PF1. Also, according to Figure 8(B), the identification information of the stacker 140 is described as downstream device i, and the identification information of the post-processing device 130 is described as downstream device ii.

[0065] Thus, when the combination of devices connected to the image inspection device 110 is changed, a profile 501 is created or selected according to that combination. Therefore, the quality of printed images can be inspected more accurately according to the combination of devices connected to the image inspection device 110.

[0066] <Technical concepts derived from examples> [perspective A1] Image forming system 100 is an example of an image inspection system. Image forming apparatus 120 is an example of an image forming apparatus that forms a printed image on a sheet corresponding to an original image. Image inspection apparatus 110 is an example of an image inspection apparatus that reads a sheet and acquires an inspection image corresponding to a printed image. Memory 202 is an example of a storage unit that stores correction data in advance to correct distortion of the inspection image relative to the printed image that occurs in the image inspection apparatus. CPU 201 is an example of a correction unit that corrects the inspection image based on the correction data. CPU 201 is an example of an inspection unit that inspects the print quality of the printed image based on the original image and the inspection image. CPU 201 is an example of a detection unit that detects whether the sheet transport device connected to the upstream or downstream side of the image inspection apparatus in the sheet transport direction has been changed. CPU 201 is an example of an update unit that updates the correction data when it is detected that the sheet transport device connected to the upstream or downstream side of the image inspection apparatus has been changed. Thus, according to this embodiment, when the sheet transport device connected to the upstream or downstream side of the image inspection apparatus is changed, the correction data is updated. Therefore, according to this embodiment, user waiting time is reduced and image inspection can be performed with high accuracy. In Figure 2, the CPU 201 is mounted on the external controller 200, but this is not mandatory. The CPU 201 may be implemented in the image forming apparatus 120, the image inspection apparatus 110, or the post-processing apparatus 130. In this case, the above description of the CPU 201 and memory 202 can be read as a description of the CPU 211 and memory 212. The external controller 200 may also function as an image inspection apparatus having a storage unit, a correction unit, an inspection unit, a detection unit, and an update unit.

[0067] [perspective A2] Memory 202 may function as a holding unit that pre-stores identification information of sheet transport devices included in the image inspection system. CPU 201 may function as a collection unit that collects identification information of sheet transport devices included in the image inspection system when predetermined collection start conditions are met. CPU 201 compares the identification information of sheet transport devices held by the holding unit with the identification information of sheet transport devices included in the image inspection system collected by the collection unit. Based on the comparison result, CPU 201 may detect whether the sheet transport device connected to the upstream or downstream side of the image inspection system in the sheet transport direction has been changed. This will ensure reliable detection of changes in sheet transport devices.

[0068] [perspective A3] Memory 202 may function as a holding unit that pre-stores position information indicating the connection position of the sheet transport device included in the image inspection system. CPU 201 may function as a collection unit that collects position information indicating the connection position of the sheet transport device included in the image inspection system when predetermined collection start conditions are met. CPU 201 compares the position information of the sheet transport device held by the holding unit with the position information of the sheet transport device included in the image inspection system collected by the collection unit. CPU 201 may detect whether the sheet transport device connected to the upstream or downstream side of the image inspection device in the sheet transport direction has been changed.

[0069] [Perspective A4] Memory 202 may function as a holding unit that pre-stores identification information of a sheet transport device connected to the upstream side of the image inspection device and identification information of a sheet transport device connected to the downstream side of the image inspection device. CPU 201 may function as a collection unit that collects identification information of a sheet transport device connected to the upstream side of the image inspection device and identification information of a sheet transport device connected to the downstream side of the image inspection device when predetermined collection start conditions are met. CPU 201 compares two combinations. The first combination is the combination of identification information of a sheet transport device connected to the upstream side of the image inspection device and identification information of a sheet transport device connected to the downstream side of the image inspection device, which is collected by the collection unit that is held by the holding unit. The second combination is the combination of identification information of a sheet transport device connected to the upstream side of the image inspection device and identification information of a sheet transport device connected to the downstream side of the image inspection device, which is collected by the collection unit. Based on the comparison result, CPU 201 may detect whether the sheet transport device connected to the upstream or downstream side of the image inspection device has changed in the sheet transport direction.

[0070] [perspective A5] The operation unit 260 may function as a reception unit that receives input of information indicating whether the combination of sheet transport devices included in the image inspection system has been changed. Based on the information received by the reception unit, the CPU 201 may detect whether the sheet transport device connected to the upstream or downstream side of the image inspection device in the sheet transport direction has been changed.

[0071] [perspective A6] The predetermined acquisition start condition may be that the image inspection system has been powered up by an external power source. The predetermined acquisition start condition may also be that the system has been instructed to start the acquisition process of information regarding the sheet transport device. This instruction may be input, for example, through the operation unit 260.

[0072] [perspectiveA7] The CPU 201 may cause the image forming apparatus to form a printed image corresponding to the test image on a sheet, and the image inspection apparatus to read the printed image formed on the sheet. Furthermore, the CPU 201 may update correction data based on the reading result of the printed image corresponding to the test image and the test image. This creates correction data that reduces distortion associated with reading the printed image. The test image may include multiple line drawings that intersect with the sheet transport direction and are equally spaced. As illustrated in Figure 4, the multiple line drawings may be perpendicular to the sheet transport direction. This improves the accuracy of detecting elongation or contraction of the inspection image in the sheet transport direction.

[0073] [perspective A8] One of the sheet transport devices connected upstream of the image inspection device may be an image forming device. Furthermore, one or more sheet transport devices may be connected between the image inspection device and the image forming device.

[0074] [perspective A9] Distortion of the inspection image includes, for example, at least one of the following: displacement of the inspection image relative to the printed image, stretching, and shrinking. Distortion of the inspection image may occur due to fluctuations in the rotational speed of the rotating body involved in sheet transport. These distortions are distortions that can occur when reading a printed image.

[0075] [perspective A10] The sheet transport device connected downstream of the image inspection device may have a sorting function. For example, the discharge tray 34b may function as a first loading unit for loading sheets with printed images that the inspection unit has determined to meet a predetermined print quality standard. The discharge tray 34a may function as a second loading unit for loading sheets with printed images that the inspection unit has determined not to meet a predetermined print quality standard.

[0076] [perspective A11] The CPU 201 may detect combinations of sheet transport devices connected to the upstream or downstream side of the image inspection device in the sheet transport direction. The CPU 201 may determine whether correction data corresponding to the combination detected by the detection unit is stored in the storage unit. Correction data corresponding to the combination detected by the detection unit may not be stored in the storage unit. In this case, the CPU 201 may function as a creation unit to create correction data corresponding to the combination detected by the detection unit. The CPU 201 may store the correction data in the storage unit in association with the combination detected by the detection unit. On the other hand, correction data corresponding to the combination detected by the detection unit may be stored in the storage unit. In this case, the CPU 201 may skip creating the correction data.

[0077] [perspective B1] The image forming system 100 is, An image forming unit (e.g., image forming apparatus 120) that forms an image on a sheet corresponding to the first image data input to the image forming system, A first transport unit (e.g., transport roller 4a) transports the sheet that has been transported from the image forming unit, A first motor (e.g., motor M1) drives the first transport unit, A second conveying unit (e.g., entrance roller 15) that conveys the sheets transported from the first conveying unit, A second motor (e.g., motor M2) drives the second transport unit, A reading unit (e.g., image reading unit 11a) reads an image on a sheet being transported by a second transport unit, It has a processor (e.g., CPU201, 211a, 211b, 211c).

[0078] The processor is The reading unit generates a second image data representing the result of reading the image on the sheet. The second image data is corrected using correction data, where the correction data is data obtained based on image data obtained by reading a predetermined image formed on a sheet by an image forming unit and image data corresponding to the predetermined image. The image formed on the sheet based on the first image data is inspected based on the corrected second image data and the first image data. It may be configured in this way.

[0079] In this way, the examination image may be corrected.

[0080] [perspective B2] An image forming system as described in viewpoint B1, wherein the image forming unit, first transport unit, and first motor may be provided in a first housing (e.g., housing 52). The second transport unit, second motor, and reading unit are provided in a second housing (e.g., housing 51) different from the first housing.

[0081] [perspective B3] The image forming system described in viewpoint B1, wherein when the processor receives an instruction to generate correction data, it may cause the image forming unit to form a predetermined image on a sheet, and the reading unit to read the image on the sheet on which the predetermined image has been formed.

[0082] The processor may generate correction data by comparing image data obtained by a reading unit reading an image on a sheet on which a predetermined image has been formed with image data corresponding to the predetermined image.

[0083] [Perspective B4] The image forming system described in viewpoint B1, wherein the image forming unit, first transport unit, and first motor are provided in a first housing (e.g., housing 52), and the second transport unit, second motor, and reading unit are provided in a second housing (e.g., housing 51) different from the first housing.

[0084] The image forming system 100 may further include a storage unit (e.g., memory 202, 212a) that stores correction data and first information relating to the housing that was connected to the second housing when the correction data was generated. The processor may correct the second image data using the correction data stored in the storage unit.

[0085] When the processor receives an instruction to generate correction data, it may obtain second information about the enclosure connected to the second enclosure.

[0086] The processor may perform a generation process to generate correction data if the first information and the second information are different. In this generation process, the processor may (i) cause an image forming unit to form a predetermined image on a sheet and cause a reading unit to read the image on the sheet on which the predetermined image has been formed, (ii) generate correction data by comparing the image data obtained by the reading unit reading the image on the sheet on which the predetermined image has been formed with the image data corresponding to the predetermined image, and (iii) store the generated correction data in a storage unit and store the second information as the first information in the storage unit.

[0087] The processor does not need to perform the generation process if the first piece of information and the second piece of information are the same.

[0088] [perspective B5] The image forming system 100 described in viewpoint B4 further includes a notification unit (e.g., operation unit 260) that notifies information indicating that the generation process was not performed when the first information and the second information are the same.

[0089] [perspective B6] In the image forming system 100 described in viewpoint B1, a predetermined image may include a plurality of line drawings that intersect with the sheet transport direction and are arranged at equal intervals in the sheet transport direction.

[0090] [perspective B7] The image forming system 100 is, An image forming unit that forms an image on a sheet corresponding to the first image data input to the image forming system, A first transport unit that transports the sheet transported from the image forming unit, A first motor that drives the first transport unit, A second transport unit transports the sheets that are transported from the first transport unit, A second motor that drives the second transport unit, A reading unit that reads the image on the sheet being transported by the second transport unit, It may have a processor.

[0091] The processor is The reading unit generates a second image data representing the result of reading the image on the sheet. The first image data is corrected using correction data, where the correction data is data obtained based on image data obtained by reading a predetermined image formed on a sheet by an image forming unit and image data corresponding to the predetermined image. The image formed on the sheet based on the first image data is inspected based on the corrected first and second image data. It may be configured in this way.

[0092] Thus, the original image (which may also be called the comparison image, ground truth image, or reference image) compared to the test image may be corrected.

[0093] [perspective B8] In the image forming system 100 described in viewpoint B7, the image forming unit, the first transport unit, and the first motor may be provided in the first housing. The second transport unit, the second motor, and the reading unit may be provided in a second housing different from the first housing.

[0094] [perspective B9] The image forming system described in viewpoint B7, When the processor receives an instruction to generate correction data, it may cause the image forming unit to form a predetermined image on a sheet, and the reading unit to read the image on the sheet on which the predetermined image has been formed.

[0095] The processor may generate correction data by comparing image data obtained by a reading unit reading an image on a sheet on which a predetermined image has been formed with image data corresponding to the predetermined image.

[0096] [perspective B10] The image forming system 100 described in viewpoint B7, The image forming unit, the first transport unit, and the first motor may be housed in the first housing. The second transport unit, the second motor, and the reading unit may be housed in a second housing different from the first housing.

[0097] The image forming system 100 further, The system may have a storage unit (e.g., memory 202, 212a) that stores correction data and first information relating to the enclosure that was connected to the second enclosure when the correction data was generated. The processor may correct the first image data using the correction data stored in the storage unit.

[0098] When the processor receives an instruction to generate correction data, it obtains second information about the enclosure connected to the second enclosure.

[0099] If the first information and the second information are different, the processor executes a generation process to generate correction data. In this generation process, the processor causes an image forming unit to form a predetermined image on a sheet and a reading unit to read the image on the sheet on which the predetermined image has been formed. The processor generates correction data by comparing the image data obtained by the reading unit reading the image on the sheet on which the predetermined image has been formed with the image data corresponding to the predetermined image. The processor then stores the generated correction data in a storage unit and stores the second information as the first information in the storage unit.

[0100] The processor does not perform the generation process if the first piece of information and the second piece of information are the same.

[0101] [perspective B11] The image forming system 100 described in viewpoint B10 further, The system may also have a notification unit (e.g., an operation unit 260) that notifies the system that the generation process was not executed when the first piece of information and the second piece of information are the same. [perspective B12] The image forming system 100 described in viewpoint B7 may include a plurality of line drawings that intersect with the sheet transport direction and are arranged at equal intervals in the sheet transport direction.

[0102] [perspective B13] The image inspection device 110 is, A transport unit that transports a sheet that has been transported from an image forming unit that forms an image on a sheet corresponding to the input first image data, A reading unit that reads the image on the sheet being transported by the transport unit, It has a processor (e.g., CPU211a).

[0103] The processor is The reading unit generates a second image data representing the result of reading the image on the sheet. The second image data is corrected using correction data, where the correction data is data obtained based on image data obtained by reading a predetermined image formed on a sheet by an image forming unit and image data corresponding to the predetermined image. The image formed on the sheet based on the first image data is inspected based on the corrected second image data and the first image data. It is structured in this way.

[0104] [Perspective B14] Image inspection device 110, A transport unit that transports a sheet that has been transported from an image forming unit that forms an image on a sheet corresponding to the input first image data, A reading unit that reads the image on the sheet being transported by the transport unit, It has a processor.

[0105] The processor is When the reading unit generates a second image data representing the result of reading the image on the sheet, The first image data is corrected using correction data, where the correction data is data obtained based on image data obtained by reading a predetermined image formed on a sheet by an image forming unit and image data corresponding to the predetermined image. An image inspection device that inspects an image formed on a sheet based on first image data, based on corrected first and second image data.

[0106] The invention is not limited to the embodiments described above, and various modifications and variations are possible without departing from the spirit and scope of the invention. Accordingly, claims are attached to disclose the scope of the invention. [Explanation of Symbols]

[0107] 100: Image inspection system, 110: Image acquisition device, 120: Image forming device, 201: CPU, 202: Memory

Claims

1. An image forming system, comprising: an image forming unit that forms an image on a sheet corresponding to first image data input to the image forming system; a first conveying unit that conveys the sheet conveyed from the image forming unit; a first motor that drives the first transport unit; a second conveying unit that conveys the sheet conveyed from the first conveying unit; a second motor that drives the second transport unit; a reading unit that reads an image on the sheet being transported by the second transport unit; a processor, The processor: generating second image data representing a result of the reading unit reading the image on the sheet; correcting the second image data using correction data, wherein the correction data is data obtained based on image data obtained by reading, with the reading unit, a predetermined image formed on a sheet by the image forming unit, and image data corresponding to the predetermined image; inspecting the image formed on the sheet based on the first image data based on the corrected second image data and the first image data; The image forming system is configured as follows.

2. 2. An image forming system as described in claim 1, wherein the image forming unit, the first transport unit, and the first motor are provided in a first housing, and the second transport unit, the second motor, and the reading unit are provided in a second housing different from the first housing.

3. 2. The image forming system according to claim 1, wherein, when the processor receives an instruction to generate the correction data, the processor causes the image forming unit to form the predetermined image on the sheet, and causes the reading unit to read the image on the sheet on which the predetermined image has been formed; An image forming system, wherein the processor is configured to generate the correction data by comparing image data obtained by the reading unit reading the image on the sheet on which the specified image is formed with image data corresponding to the specified image.

4. 2. The image forming system according to claim 1, wherein the image forming unit, the first transport unit, and the first motor are provided in a first housing, and the second transport unit, the second motor, and the reading unit are provided in a second housing different from the first housing; the image forming system further includes a storage unit in which the correction data and first information relating to a housing connected to the second housing when the correction data was generated are stored, and the processor corrects the second image data using the correction data stored in the storage unit; When the processor receives the instruction to generate the correction data, it acquires second information regarding a housing connected to the second housing; If the first information and the second information are different, the processor executes a generation process to generate the correction data, wherein in the generation process, the processor causes the image forming unit to form the predetermined image on the sheet and causes the reading unit to read the image on the sheet on which the predetermined image has been formed, and the processor generates the correction data by comparing image data obtained by the reading unit reading the image on the sheet on which the predetermined image has been formed with image data corresponding to the predetermined image, and the processor stores the generated correction data in the storage unit and stores the second information in the storage unit as the first information, The processor does not execute the generation process when the first information and the second information are the same.

5. 5. The image forming system according to claim 4, further comprising a notification unit that notifies information indicating that the generation process was not performed when the first information and the second information are the same.

6. 2. The image forming system according to claim 1, An image forming system, wherein the predetermined image includes a plurality of line drawings that intersect with a transport direction of the sheet and are arranged at equal intervals in the transport direction of the sheet.

7. An image forming system, comprising: an image forming unit that forms an image on a sheet corresponding to first image data input to the image forming system; a first conveying unit that conveys the sheet conveyed from the image forming unit; a first motor that drives the first transport unit; a second conveying unit that conveys the sheet conveyed from the first conveying unit; a second motor that drives the second transport unit; a reading unit that reads an image on the sheet being transported by the second transport unit; a processor, The processor: generating second image data representing a result of the reading unit reading the image on the sheet; correcting the first image data using correction data, wherein the correction data is data obtained based on image data obtained by reading, by the reading unit, a predetermined image formed on a sheet by the image forming unit, and image data corresponding to the predetermined image; inspecting the image formed on the sheet based on the first image data based on the corrected first image data and the second image data; The image forming system is configured as follows.

8. 8. An image forming system according to claim 7, wherein the image forming unit, the first transport unit and the first motor are provided in a first housing, and the second transport unit, the second motor and the reading unit are provided in a second housing different from the first housing.

9. 8. The image forming system according to claim 7, When the processor receives the instruction to generate the correction data, the processor causes the image forming unit to form the predetermined image on the sheet, and causes the reading unit to read the image on the sheet on which the predetermined image has been formed; The processor generates the correction data by comparing image data obtained by reading the image on the sheet on which the predetermined image is formed by the reading unit with image data corresponding to the predetermined image. The image forming system is configured as follows.

10. 8. The image forming system according to claim 7, the image forming unit, the first transport unit, and the first motor are provided in a first housing, and the second transport unit, the second motor, and the reading unit are provided in a second housing different from the first housing; The image forming system further comprises: a storage unit in which the correction data and first information relating to a housing that was connected to the second housing when the correction data was generated are stored, and the processor corrects the first image data using the correction data stored in the storage unit; When the processor receives the instruction to generate the correction data, it acquires second information regarding a housing connected to the second housing; If the first information and the second information are different, the processor executes a generation process to generate the correction data, wherein in the generation process, the processor causes the image forming unit to form the predetermined image on the sheet and causes the reading unit to read the image on the sheet on which the predetermined image has been formed, and the processor generates the correction data by comparing image data obtained by the reading unit reading the image on the sheet on which the predetermined image has been formed with image data corresponding to the predetermined image, and the processor stores the generated correction data in the storage unit and stores the second information in the storage unit as the first information, The processor does not execute the generation process when the first information and the second information are the same.

11. The image forming system according to claim 10, further comprising: an image forming system including a notification unit that notifies information indicating that the generation process was not executed when the first information and the second information are the same;

12. 8. The image forming system according to claim 7, wherein the predetermined image includes a plurality of line drawings that intersect with the conveying direction of the sheet and are arranged at equal intervals in the conveying direction of the sheet.

13. An image inspection device, comprising: a conveying unit that conveys a sheet conveyed from an image forming unit that forms an image corresponding to the input first image data on the sheet; a reading unit that reads an image on the sheet being transported by the transport unit; a processor, The processor: generating second image data representing a result of the reading unit reading the image on the sheet; correcting the second image data using correction data, wherein the correction data is data obtained based on image data obtained by reading, with the reading unit, a predetermined image formed on a sheet by the image forming unit, and image data corresponding to the predetermined image; inspecting the image formed on the sheet based on the first image data based on the corrected second image data and the first image data; The image inspection device is configured as follows.

14. An image inspection device, comprising: a conveying unit that conveys a sheet conveyed from an image forming unit that forms an image corresponding to the input first image data on the sheet; a reading unit that reads an image on the sheet being transported by the transport unit; a processor, The processor: When the reading unit generates second image data representing the result of reading the image on the sheet, correcting the first image data using correction data, wherein the correction data is data obtained based on image data obtained by reading, by the reading unit, a predetermined image formed on a sheet by the image forming unit, and image data corresponding to the predetermined image; an image inspection device that inspects an image formed on the sheet based on the first image data, based on the corrected first image data and the second image data; 15. An image forming system, comprising: an image forming unit that forms an image on a sheet; a reading unit that reads the image formed on the sheet; one or more processors that generate scanned image data corresponding to the image scanned by the scanning unit; When an instruction to generate correction data for correcting the read image data is given, (1) the image forming unit forms a test image on a sheet, (2) the reading unit reads the test image formed on the sheet, and (3) the one or more processors generate the correction data based on the read image of the test image, When an image formed on a sheet is inspected, (1) the image forming unit forms a first image on the sheet corresponding to input first image data, (2) the reading unit reads the first image formed on the sheet, and (3) the one or more processors generate first read image data corresponding to the first image and correct the first read image data using the correction data. an image forming system, wherein the one or more processors inspect the first image formed on the sheet based on the corrected first read image data and the input first image data;

16. An image forming system as described in claim 15, wherein the one or more processors generate the correction data by comparing second read image data corresponding to the read image of the test image with second image data corresponding to the test image.

17. An image forming system as described in claim 15, wherein the test image includes a plurality of line images arranged at equal intervals in the sheet transport direction and intersecting the transport direction.

18. An image forming system, comprising: an image forming unit that forms an image on a sheet; a reading unit that reads the image formed on the sheet; one or more processors that generate scanned image data corresponding to the image scanned by the scanning unit; When an instruction to generate correction data for correcting the read image data is given, (1) the image forming unit forms a test image on a sheet, (2) the reading unit reads the test image formed on the sheet, and (3) the one or more processors generate the correction data based on the read image of the test image, When an image formed on a sheet is inspected, (1) the one or more processors correct the input first image data using the correction data, (2) the image forming unit forms a first image on the sheet corresponding to the corrected first image data, (3) the reading unit reads the first image formed on the sheet, and (4) the one or more processors generate first read image data corresponding to the first image, The one or more processors inspect the first image formed on the sheet based on the corrected first image data and the first read image data.

19. An image forming system as described in claim 18, wherein the one or more processors generate correction data by comparing second read image data corresponding to the read image of the test image with second image data corresponding to the test image.

20. An image forming system as described in claim 18, wherein the test image includes a plurality of line images arranged at equal intervals in the sheet transport direction and intersecting the transport direction.

Images