Inspection system, inspection device, its control method and program

Abstract

To solve the problem in which in an inspection device for a printed material, changing a medium of the printed material changes the determination accuracy of the inspection device.SOLUTION: An inspection system includes a printer that creates a printed material, and an inspection device that inspects the printed material. The printer measures the spectral reflectance of a medium of the printed material and transmits the measured spectral reflectance to the inspection device. The inspection device acquires a normalization coefficient corresponding to the medium based on the spectral reflectance, and compares image data obtained by normalizing image data obtained by reading an image of the printed material according to the normalization coefficient with a reference image to determine the quality of the printed material.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to an inspection system, an inspection apparatus, a control method thereof, and a program.

Background Art

[0002] In printing that requires high quality such as production printing, the quality of printed matter has been ensured by manually inspecting each sheet of printed matter. However, in recent years, an inspection apparatus has been used that electrically reads printed matter to obtain an electronic image of the printed matter and determines whether it is correctly printed based on the electronic image.

[0003] Such an inspection apparatus arranges an area sensor or a line sensor at the paper discharge part of a printing machine or the like, photographs the printed matter with the sensor, and compares the obtained image data with a reference image stored as a correct image. Then, when it matches the reference image, it is determined as good, and when it does not match, it is determined as defective. For example, Patent Document 1 describes performing inspection using a line sensor of an inspection apparatus and changing the conveyance speed of the printed matter according to the determination result of good or defective of the printed matter.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in the inspection apparatus described in Patent Document 1, the normalization method at the time of reading by the line sensor is fixed. That is, the normalization method is not dynamically changed according to the environment or measurement results. Therefore, there is a problem that the determination accuracy changes when the medium used for the printed matter to be inspected is changed. That is, there is a problem that printing that was conventionally determined to be good is determined to be defective, and vice versa.

[0006] The object of the present invention is to solve at least one of the problems of the prior art described above.

[0007] The object of the present invention is to provide a technology that enables inspection without change in judgment accuracy, even when the media used for the printed material being inspected is changed. [Means for solving the problem]

[0008] To achieve the above objective, an inspection system according to one aspect of the present invention has the following configuration. That is, An inspection system comprising a printing apparatus for producing printed materials and an inspection apparatus for inspecting said printed materials, The aforementioned printing apparatus, A measuring means for measuring the spectral reflectance of the media of the printed material, The system includes a transmitting means for transmitting the spectral reflectance measured by the measuring means to the inspection device, The inspection device, An acquisition means for obtaining a normalization coefficient corresponding to the media based on the spectral reflectance, A reading means that reads the image of the printed material and obtains image data, The device is characterized by having a determination means that determines the quality of the printed material by comparing the image data obtained by the reading means, normalized according to the normalization coefficient, with a reference image. [Effects of the Invention]

[0009] According to the present invention, even if the media used for the printed material being inspected is changed, the determination can be made with the same accuracy.

[0010] Other features and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings. In the accompanying drawings, the same or similar components are given the same reference numeral. [Brief explanation of the drawing]

[0011] The attached drawings are included in the specification, form a part thereof, show embodiments of the present invention, and are used to explain the principles of the present invention together with the description. [Figure 1] Overall configuration diagram of the inspection system according to Embodiment 1 of the present invention. [Figure 2] Schematic cross-sectional view of the printing device and the inspection device according to Embodiment 1. [Figure 3] Block diagram for explaining the functional configurations of the printing device, inspection device, and PC according to Embodiment 1. [Figure 4] Sequence diagram for explaining the processing flow when the inspection device according to Embodiment 1 creates a reference image for inspecting a printed matter. [Figure 5] Diagram for explaining background part detection during RIP processing. [Figure 6] Sequence diagram for explaining the processing flow when the inspection device according to Embodiment 1 inspects a printed matter. [Figure 7] Flowchart for explaining the inspection process executed by the inspection device according to Embodiment 1. [Figure 8] Flowchart for explaining the process of obtaining the total number of pixels with a difference value greater than a predetermined value, which is executed at S703 in FIG. 7. [Figure 9] Sequence diagram for explaining the inspection process in the inspection system according to Embodiment 2. [Figure 10] Sequence diagram for explaining the inspection process in the inspection system according to Embodiment 3. [Figure 11] Flowchart for explaining the process by the printing device according to Embodiment 1.

Modes for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims. Although a plurality of features are described in the embodiments, not all of these plurality of features are essential for the invention, and the plurality of features may be arbitrarily combined. Further, in the accompanying drawings, the same or similar configurations are denoted by the same reference numerals, and redundant descriptions are omitted.

[0013] [Embodiment 1] FIG. 1 is an overall configuration diagram of an inspection system according to Embodiment 1 of the present invention.

[0014] This inspection system includes a printing device 100, an inspection device 200 that inspects a printed matter printed by the printing device 100, and a PC 300 that inputs a print job to the printing device 100 to cause printing. The printing device 100, the inspection device 200, and the PC 300 are connected via a LAN 400. Also, the inspection device 200 is directly connected to the printing device 100, and it will be described as a configuration capable of transmitting and receiving commands without going through the PC 300 or the LAN 400. Further, the printing device 100 and the inspection device 200 are connected via a conveyance path so that the medium (printed matter) discharged from the printing device 100 can be directly conveyed to the inspection device 100.

[0015] FIG. 2 is a schematic cross-sectional view of the printing device 100 and the inspection device 200 according to Embodiment 1.

[0016] Reference numerals 101 to 104 respectively indicate image forming stations for performing yellow, magenta, cyan, and black color printing. For the image forming stations 101 to 104, image forming means such as an electrophotographic method or an inkjet method can be considered, but the present invention does not depend on this. Here, an example of the electrophotographic method will be described. Also, single-color printing, for example, a configuration with only the black station (K) 104 is also feasible.

[0017] The paper feeder 115 has multiple paper feed stages, for example, a paper feed stage 105 equipped with a first media and a paper feed stage 106 equipped with a second media of a different type from the first media. The transfer belt 108 rotates clockwise in the figure, and colorants (toner) are transferred from the image forming stations 101 to 104. Furthermore, the toner image transferred to the transfer belt 108 is transferred at the contact point to the media (paper, sheet, etc.) being transported downstream along the paper transport path 109.

[0018] Furthermore, the colorimeter sensor 107 (for example, a spectrophotometric colorimeter) is positioned on the paper transport path 109 and can measure the spectral reflectance and CIE-L*a*b* value of the colorant transferred to the media. By using the colorimeter sensor 107, the printing device 100 can perform calibration (adjustment of print density gradation) during printing or at startup.

[0019] The printing device 100 and the inspection device 200 are connected by a paper transport path 109, and the printed materials (sheets) after printing are directly transported to the paper transport path of the inspection device 200. The image sensor 110 then photographs the printed materials on the transport path and performs inspection of the printed materials. The sorting device 111 on the transport path sorts the printed materials according to the inspection results so that they are discharged to the paper discharge section 112 or paper discharge section 113. For example, printed materials that pass the inspection are discharged to the paper discharge section 112, and printed materials that fail the inspection are discharged to the paper discharge section 113. In Figure 2, reference number 116 indicates the second colorimeter sensor, and reference number 114 indicates the reference whiteboard. The second colorimeter sensor 116 and the reference whiteboard 114 will be described later.

[0020] Figure 3 is a block diagram illustrating the functional configurations of the printing device 100, inspection device 200, and PC 300 according to Embodiment 1. Each function is realized by the CPU of each device executing a program loaded into the corresponding RAM. However, these functions can also be realized using hardware such as an ASIC, rather than a CPU or program.

[0021] The PC300 includes a reference image creation unit 301 that creates print data for printing a reference image and instructs the printing device 100 to print it, and a reference image approval unit 302 that approves the image transferred from the inspection device 200 as the reference image. The print command 303 is a command that instructs the printing device 100 to print.

[0022] The printing device 100 has a CPU 330, RAM 331, and ROM 332, and the CPU 330 executes a program loaded in RAM 331 to achieve the function indicated by reference number 333. The RIP processing unit 304 rasterizes the print data included in the print job received from the PC 300 and creates a bitmap image to be used for printing. The print control unit 305 controls printing to the media by controlling the image forming stations 101 to 104, etc. The background area detection unit 306 detects the background area of ​​the image data. The media transport control unit 308 controls the transport of the printed material. The paper feed control unit 309 controls the feeding of media to the image forming stations 101 to 104. The spectroscopic measurement unit 307 uses the colorimeter sensor 107 to measure the CIE-XYZ of the media that has been transferred with colorants and is being transported along the transport path 109.

[0023] Next, the configuration of the inspection device 200 will be described. The inspection device 200 has a CPU 340, RAM 341, and ROM 342, and the CPU 340 executes the program loaded in RAM 341 to achieve the function indicated by reference number 343. The reading control unit 312 controls the image sensor 110 to capture images of the transported printed media. The normalization processing unit 313 determines the normalization coefficient of the image sensor 110 to match the media. The inspection processing unit 314 performs an inspection process to determine the quality of the printed material by comparing the image of the material to be inspected (the image obtained by reading the media) with a reference image. The reference image creation unit 315 generates a reference image based on the image data obtained by reading the printed material with the image sensor 110. The sorting processing unit 316 controls the output destination of the printed material according to its quality.

[0024] Figure 4 is a sequence diagram illustrating the processing flow when the inspection device 200 according to Embodiment 1 creates a reference image for inspecting printed materials.

[0025] In S401, PC300 sends a reference image creation command to the printer 100, instructing it to create a reference image. This reference image creation command contains a PDL (Page Description Language). Upon receiving this command, the printer 100's RIP processing unit 304 executes RIP processing in S402. Here, according to the PDL, it generates, for example, the bitmap image in Figure 5(A) and the flag image in Figure 5(B). The flag image refers to metadata (position, attribute information, etc.) for each drawing target necessary for optimal printing.

[0026] Next, proceeding to S403, the printing device 100 uses the background area detection unit 306 to perform background area detection processing to identify the background of the printed image, that is, the areas that will not be printed. For example, using the flag image in Figure 5(B), areas where attribute information is not placed can be considered areas where the image is not printed, and measurement points for the media can be determined. Alternatively, using Figure 5(A), a region with a luminance signal value of (Red,Green,Blue)=(255,255,255) or a density signal value of (Cyan,Magenta,Yellow,Black)=(0,0,0,0) and where an area of ​​approximately (width, height)=(100 pixels, 100 pixels) can be secured is identified as a measurement point. The position and size of that region are then stored in the memory area (not shown) of the RAM 331.

[0027] Next, the process proceeds to S404, where the printing device 100 executes the printing process using the printing control unit 305. The printing control unit 305 generates halftone image data using the bitmap image and flag image created in S402, and transfers this image data to each of the CMYK image forming stations 101 to 104. Furthermore, it rotates the transfer belt 108 to transfer the halftone image data transferred to each station onto the transfer belt 108 using electrophotography or inkjet methods. The paper feed control unit 309 also picks up the first media from the first cassette 105 of the paper feed unit 115, and the media transport control unit 308 transports the first media onto the transport path 109. The media transport control unit 308 controls the colorant transferred to the transfer belt 108 so that it comes into contact with the first media at the point where the transport path 109 and the transfer belt 108 meet, and at that point, the colorant transferred to the transfer belt 108 is transferred to the first media.

[0028] Next, in S405, the printing device 100 performs spectral reflectance measurement using the spectroscopic measurement unit 307. The spectroscopic measurement unit 307 uses the colorimetric sensor 107 to generate values, for example, in the CIE-XYZ color system. In S404, the first media on which the colorant has been transferred is transported along the transport path 109, and when the measurable area of ​​the colorimetric sensor 107 overlaps with the measurement point of the background region detected in S403, the CIE-XYZ measurement of the first media is performed. Note that if the cassette has already been measured, this measurement process can be simplified. Typically, the measurement speed of the colorimetric sensor 107 used for measurement is often faster than the printing speed of the printing device 100, so it is not necessary to slow down to match the speed of the colorimetric sensor 107. The method of simplification will be described later.

[0029] Then, in S406, the printing device 100 transmits the CIE-XYZ value, which is assumed to be the brightest among the printed materials in S404, to the inspection device 200 via LAN 400. In a typical printing device, the first media is usually the brightest, but the first media may be dark, or the colorant may be a special color and therefore bright. In this case, the CIE-XYZ value of the toner is read from the toner information 310 stored in the printing device 100 and compared with the CIE-XYZ of the first media. As a result of this comparison, the value considered to be the brightest is selected. However, in Embodiment 1, for the sake of simplicity, the following explanation will assume that the first media had the brightest value.

[0030] In S407, the inspection device 200 determines the normalization coefficient of the image sensor 110, which is matched to the first media, for use in the normalization processing unit 313. This normalization coefficient is the coefficient used by the image sensor 110 to normalize the image of the media under inspection when converting it into a digital image, according to the white point (R,G,B)=(255,255,255), which is the maximum brightness of each color. This normalization coefficient is obtained by the following equations (1) and (2).

[0031] (Rw,Gw,Bw) T =MatA × (CIE-X, CIE-Y, CIE-Z) T ...Formula (1) Here, Rw, Gw, and Bw are the predicted RGB values ​​when the media measurement point is read by the image sensor 110 in S405. The white point is defined by MatA. MatA is a 3x3 matrix coefficient used to normalize the CIE-XYZ received by the image sensor 110 to a fixed white point. For example, if the luminance CIE-XYZ=(85,90,93) is defined as the white point, then it is defined so that the white point is (R,G,B)=(255,255,255). Also, CIE,X,Y,Z are the CIE-XYZ values ​​of the media measurement point measured in S405.

[0032] Next, using the value calculated in equation (1) above, the normalization coefficient is calculated using the following equation (2).

[0033] Cr' = Cr × Rw / 255 Cg' = Cg × Gw / 255 Cb'=Cb×Bw / 255...Equation (2) Here, Cr', Cg', and Cb' are the normalization coefficients when the white point is changed to the value measured by S405, and Cr, Cg, and Cb are the original normalization coefficients of the image sensor 110, which was determined so that the white point is (R,G,B)=(255,255,255).

[0034] Next, in S408, the printing device 100 transports the media that has been printed in S404 to the inspection device 200 via the transport path 109. Then, in S409, the inspection device 200 uses the reading control unit 312 to capture an image of the transported printed media with the image sensor 110. At this time, calculations are performed to normalize the image data obtained from the reading. Furthermore, a bit depth conversion is performed during the calculation. Normally, when the output of an image sensor is converted to digital information by an A / D converter, the conversion is done with a bit depth of about 36 bits per pixel (12 bits per color) for RGB. However, in order for the inspection device 200 to process a 12-bit color image, the comparison processing and other calculations described later must be performed in 12 bits, which increases the cost. Therefore, the image data is converted to 8 bits per color, i.e., 24 bits per pixel. Equation (3) below shows the calculation including the bit depth conversion.

[0035] Video_r'=int(float(Cr×Video_r ÷ White_r)×float(2 8 ÷2 12 )) Video_g'=int(float(Cg×Video_g ÷ White_g)×float(2 8 ÷2 12 )) Video_b'=int(float(Cb×Video_b ÷ White_b)×float(2 8 ÷2 12 )) ...Formula (3) Here, Video_r,g,b are the digitized video signals from the image sensor 110. Video_r',Video_g',Video_b' are the video signals used by the inspection device 200. White_r,g,b are the values ​​obtained when the image sensor 110 reads the reference whiteboard 114, and are usually obtained before the image sensor 110 acquires the image from the media.

[0036] By using this equation (3), image data is generated with CIE-XYZ measured in S405 as the white point.

[0037] Next, in S410, the inspection device 200 generates a reference image using the reference image creation unit 315. A reference image is an image used as a reference when inspecting printed materials. In S409, the reference image creation unit 315 stores the image data obtained by reading the printed material with the image sensor 110 as a reference image in the RAM 341. Then, in S411, the inspection device 200 transfers the reference image generated in S410 to the PC 300. As a result, in S412, the PC 300 performs approval of the reference image using the reference image approval unit 302. In this way, the inspection device 200 registers the reference image for inspection and uses it for subsequent inspections.

[0038] Here, the simplification of the spectroscopic measurement unit 307 in S405 will be explained using the flowchart in Figure 11. Note that the flowchart in Figure 11 shows the process executed by the CPU 330 of the printing device 100 according to the program that has been expanded from ROM 332 to RAM 331.

[0039] Figure 11 is a flowchart illustrating the processing performed by the printing apparatus 100 according to Embodiment 1.

[0040] In S1101, the CPU 330 obtains from the cassette information 311 whether the cassette fed in S404 of Figure 4 contains media whose spectral reflectance has already been measured. The cassette information 311 stores the past spectral reflectance of the media contained in the cassette, and by referring to this cassette information 311, it is possible to determine whether the cassette contains media whose spectral reflectance has already been measured. If it is determined that the cassette contains media whose spectral reflectance has already been measured, the process proceeds to S1102, where the spectral measurement value of the fed cassette is obtained from the cassette information 311, and this process ends.

[0041] On the other hand, if it is determined that the cassette contains media that has not yet been measured, the process proceeds to S1103, where the spectral reflectance of the media fed from that cassette is measured using the spectral measurement unit 307. The operation of the spectral measurement unit 307 has already been explained and will be omitted here. The process then proceeds to S1104, where the spectral reflectance measured in S1103 is stored in the cassette information 311. This process allows the measurement of spectral reflectance to be omitted the next time media is fed from the same cassette. If the media loaded in the cassette changes, the cassette information 311 is deleted.

[0042] Next, we will explain the inspection of printed materials using the sequence diagram in Figure 6.

[0043] Figure 6 is a sequence diagram illustrating the processing flow when the inspection device 200 according to Embodiment 1 performs inspection of printed materials.

[0044] When PC300 issues print command 303 in S601, printing starts in the printer 100. Printer 100 executes steps S602 to S603. This process is the same as steps S402 to S403 in Figure 4, which have already been explained, so their explanation is omitted.

[0045] In S604, the printing device 100 executes the printing process using the printing control unit 305. Here, halftone image data is generated using the bitmap image and flag image created in S602, and this image data is transferred to each of the CMYK stations 101 to 104. Furthermore, the transfer belt 108 is rotated to transfer toner images corresponding to the halftone image data transferred to each station onto the transfer belt 108. Meanwhile, the paper feed control unit 309 picks up either the first media or the second media from the first cassette 105 of the paper feed unit 112, and the media transport control unit 308 transports it onto the transport path 109. To explain the effects of this embodiment clearly, the second media is used in this example.

[0046] Here, the second media is a darker paper than the first media (for example, a media with a spectral reflectance about 20% lower). Normally, when printing on the second media, it is necessary to repeat the reference image registration sequence shown in Figure 4, but this is not necessary when using Embodiment 1. The media transport control unit 308 controls the colorant (toner image) transferred to the transfer belt 108 so that it comes into contact with the second media at the contact point between the transport path 109 and the transfer belt 108, and the colorant (toner image) is transferred to the second media at that contact point.

[0047] Since steps S605 to S609 are the same as steps S405 to S409 in Figure 4 above, their explanation will be omitted. It is assumed that the image to be inspected is stored in the storage device (for example, RAM 341) of the inspection device 200 after the processing up to S609.

[0048] In S610, the inspection device 200 performs inspection processing by the inspection processing unit 314. The method of this inspection processing will be described later using the flowcharts in Figures 7 and 8. Then, in S611, the inspection device 200 performs sorting processing by the sorting processing unit 316. This sorting processing unit 316 sorts the media into good and bad using the sorting device 111 on the transport path. For example, in this case, the second media to be inspected that was determined to be good in S610 is discharged to the paper discharge unit 112, and the second media that was determined to be bad is discharged to the paper discharge unit 113.

[0049] Next, the inspection process performed by the inspection processing unit 314 of the inspection device 200 according to Embodiment 1 will be explained with reference to the flowchart in Figure 7. Although there are various methods for inspection processing, here we will explain the method of counting the difference amount. Note that the flowchart in Figure 7 shows the process executed by the CPU (not shown) of the inspection device 200 according to the program stored in the memory device (not shown).

[0050] Figure 7 is a flowchart illustrating the inspection process performed by the inspection device 200 according to Embodiment 1.

[0051] In S701, the CPU 340 acquires image data of the document to be inspected, obtained by reading the original document in S609 of Figure 6. Next, in S702, the CPU 340 acquires a reference image. Then, in S703, the CPU 340 calculates the difference value of each corresponding pixel between the reference image and the image data of the document to be inspected, and calculates the total number of pixels whose difference value is greater than a predetermined value. The process in S703 will be described later with reference to the flowchart in Figure 8.

[0052] Then, proceeding to S704, the CPU340 determines whether the total number of pixels whose difference value is greater than a predetermined value exceeds threshold 2. If it determines that it does, proceed to S705, where it determines that the image being inspected is defective and terminates this process. On the other hand, if it determines in S704 that the total number of pixels whose difference value is greater than a predetermined value does not exceed threshold 2, proceed to S706, where it determines that the image being inspected is good and terminates this process.

[0053] Figure 8 is a flowchart illustrating the process performed in step S703 of Figure 7 to determine the total number of pixels whose difference value is greater than a predetermined value. The flowchart in Figure 8 represents the process executed by the CPU 340 of the inspection device 200 according to the program loaded into RAM 341.

[0054] In S801, the CPU 340 initializes the counter in RAM 341 and the position of the pixel of interest. Next, in S802, the CPU 340 calculates the brightness difference between the pixel of interest in the reference image and the pixel of interest in the image to be inspected at the position of the pixel of interest. In Embodiment 1, since it is an RGB color image, the absolute value of the difference in brightness of each RGB component is taken, and the maximum value is adopted. Then, in S803, the CPU 340 determines whether the difference value obtained in S802 is greater than a predetermined threshold 1. Here, if the value of threshold 1 is small, the inspection by the inspection device 200 will be strict, and if the value of threshold 1 is large, the inspection will be lenient. In Embodiment 1, since the image is normalized for each media in S407 and S607, there is no need to adjust the value of threshold 1 even if the media changes. In S803, if the CPU 340 determines that the difference value is greater than threshold 1, it proceeds to S804, increments the value of the pixel counter (+1), and proceeds to S805. On the other hand, in S803, if the CPU340 determines that the difference value is equal to or less than the threshold of 1, it skips S804 and proceeds to S805. In S805, the CPU340 determines whether the comparison between all pixels has been completed. If it has not been completed, it proceeds to S806, moves the position of the pixel of interest to the next pixel position, changes the pixel of interest to the next pixel, and proceeds to S802. On the other hand, if the CPU340 has completed the comparison between all pixels in S805, it terminates this process.

[0055] This process stores in the pixel counter the total number of pixels whose brightness difference between the reference image and the image being inspected is greater than a predetermined value (threshold 1).

[0056] Furthermore, this process assumes that the positions of the reference image and the image to be inspected match when high-precision alignment is performed. Robustness of alignment and comparison is not considered in this embodiment, and therefore will not be mentioned. As explained above, according to Embodiment 1, by generating normalized comparison image data for each media, it is possible to perform inspection of a different type of second media even when using a reference image created on the first media. Therefore, it has the effect of being able to make judgments with the same accuracy even when the inspection target is on a different media.

[0057] [Embodiment 2] In Embodiment 1 described above, the PC 300 was described as registering a reference image by printing a reference image through the execution of the reference image creation unit 301 and then reading that reference image. However, it is also possible to perform inspection by registering a reference image without reading the printed reference image. Therefore, Embodiment 2 describes an example of inspection performed by registering a reference image without reading the printed reference image. Note that the system configuration and hardware configuration such as the printing device and inspection device in Embodiment 2 are the same as those in Embodiment 1 described above, so their explanation will be omitted.

[0058] Figure 9 is a sequence diagram illustrating the inspection process in the inspection system according to Embodiment 2. Since steps S901 to S909 are the same as steps S601 to S609 in Figure 6, their explanation will be omitted.

[0059] In S910, the printing device 100 sends the RIP image created in S902 to the inspection device 200 in place of the reference image. Since the RIP image is not affected by the brightness of the first and second media, the background of the RIP image (Figure 5) (Figure 5(B)) is composed of (R,G,B)=(255,255,255) in the bitmap image of Figure 5(A). Therefore, it is a bitmap image equivalent to the reference image created in Figure 4. As a result, the inspection process in S911 performs the same process as the inspection process in S610 in Figure 6. S912 is the same process as S611, so its explanation is omitted.

[0060] As described above, according to Embodiment 2, by transmitting the reference image to the inspection device as a RIP image, the inspection of printed materials can be performed without being affected by the media used to print the reference image. Therefore, even when inspecting objects on different media, the same accuracy can be maintained.

[0061] [Embodiment 3] In embodiments 1 and 2 described above, the brightness of the media was detected using the colorimeter sensor 107 shown in Figure 2. This is because, normally, if color measurement is performed after the transfer of toner and ink to the media, it is possible to measure toner density and other parameters, and to calibrate the printing device. However, by using the colorimeter sensor 116 shown in Figure 2 before the transfer of toner and ink, the background area detection process (S403, S603, S903) can be skipped. This will be described as embodiment 3.

[0062] Figure 10 is a sequence diagram illustrating the inspection process in the inspection system according to Embodiment 3.

[0063] S1001 to S1002 are the same processes as S901 to S902 in Figure 9. However, in Figure 10, the colorimetric sensor 116 in Figure 2 is used to detect the color of the media (sheet) before printing, and based on the detection result, in S1005, the CIE-XYZ expected to be the brightest is transmitted to the inspection device 200 via LAN 400. In this case, as mentioned above, detection of the background area is unnecessary. S1003 to S1011 are the same processes as S904 to S912 in Figure 9.

[0064] As described above, according to Embodiment 3, the reference image is transmitted to the inspection device as a RIP image, and the brightness of the media before transfer is detected, so the brightness of the media can be detected without detecting the background area. In this way, the inspection of printed materials can be performed without being affected by the media used to print the reference image. Therefore, even if the inspection target is made of different media, the judgment can be made with the same accuracy.

[0065] (Other embodiments) The present invention can also be realized by supplying a program that implements one or more of the functions of the above-described embodiments to a system or device via a network or storage medium, and by having one or more processors in the computer of that system or device read and execute the program. It can also be realized by a circuit (e.g., an ASIC) that implements one or more functions.

[0066] The present 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, the following claims are attached to make the scope of the invention public. [Explanation of symbols]

[0067] 100…Printing device, 107…Colorimeter sensor, 110…Image sensor, 200…Inspection device, 300…PC

Claims

1. An inspection system comprising a printing apparatus for producing printed materials and an inspection apparatus for inspecting said printed materials, The aforementioned printing apparatus, A measuring means for measuring the spectral reflectance of the media of the printed material, The system includes a transmitting means for transmitting the spectral reflectance measured by the measuring means to the inspection device, The inspection device, An acquisition means for obtaining a normalization coefficient corresponding to the media based on the spectral reflectance, A reading means that reads the image of the printed material and obtains image data, A determination means for determining the quality of the printed material by comparing the image data obtained by the reading means with a reference image, after the image data has been normalized according to the normalization coefficient. An inspection system characterized by having the following features.

2. The inspection device, The printing device receives the spectral reflectance of the printed material on which the reference image has been printed, and the spectral reflectance of the media on which the reference image has been printed, The inspection system according to claim 1, characterized in that the image data obtained by reading the reference image of the printed material with the reading means is normalized according to the normalization coefficient and the resulting image data is registered as the reference image.

3. The inspection system according to claim 1, characterized in that the inspection device receives a bitmap image of the reference image and registers it as the reference image.

4. The inspection system according to any one of claims 1 to 3, characterized in that the measuring means identifies areas on the printed material's media where no image is printed, and measures the spectral reflectance of those areas with a first sensor.

5. The inspection system according to any one of claims 1 to 3, characterized in that the measurement means measures the spectral reflectance of the media before printing using a second sensor.

6. The aforementioned printing apparatus, The system further includes a storage means for storing the spectral reflectance measured by the measurement means in association with the cassette on which the media is mounted. The inspection system according to claim 1, wherein, if the spectral reflectance corresponding to the cassette on which the printed material media is mounted is stored in the storage means, the transmitting means transmits the spectral reflectance stored in the storage means without performing a measurement by the measuring means.

7. The inspection system according to claim 6, characterized in that when the media mounted on the cassette is changed, the spectral reflectance corresponding to the cassette stored in the storage means is deleted.

8. An inspection device for inspecting printed materials printed by a printing machine, A registration means for registering a reference image, An acquisition means for obtaining a normalization coefficient corresponding to the media based on the spectral reflectance of the media of the printed material, A reading means that reads the image of the printed material and obtains image data, A determination means for determining the quality of the printed material by comparing the image data obtained by the reading means with the reference image registered in the registration means, which is obtained by normalizing the image data obtained by the reading means according to the normalization coefficient. An inspection device characterized by having the following features.

9. The inspection apparatus according to claim 8, characterized in that the registration means receives from the printing device the printed material on which the reference image has been printed and the spectral reflectance of the media of the printed material on which the reference image has been printed, and the reading means reads the reference image of the printed material and registers the image data obtained by normalizing the image data according to the normalization coefficient as the reference image.

10. The inspection apparatus according to claim 8, characterized in that the registration means receives a bitmap image of the reference image and registers it as the reference image.

11. The inspection apparatus according to any one of claims 8 to 10, characterized in that the inspection apparatus receives the printed material from the printing apparatus via a transport path.

12. A control method for controlling an inspection device that inspects printed materials produced by a printing device, The registration process involves registering a reference image, An acquisition step of obtaining a normalization coefficient corresponding to the media based on the spectral reflectance of the media of the printed material, A reading step of reading the image of the printed material to obtain image data, A determination step involves comparing the image data obtained in the reading step with the reference image registered in the registration step to determine whether the printed material is of good or bad quality. A control method characterized by having the following features.

13. A program for causing a computer to perform each step of the control method described in claim 12.

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