Image inspection system and image inspection method

Abstract

The present invention provides an image inspection device, an image inspection method, and an image inspection program that can improve the productivity of inspecting printed materials by printing without requiring prior registration of reference images, while also being able to properly inspect printed materials by printing that require prior registration of reference images. [Solution] The image inspection device 300 includes an image forming unit 330, a reference image generation unit 380, and an image inspection unit 350. The image forming unit 330 forms an image on a recording medium based on acquired image data. The reference image generation unit 380 generates a reference image used for inspecting the image formed on the recording medium. The image inspection unit 350 inspects the image formed on the recording medium based on the reference image. The image inspection device 300 has a first inspection mode in which a reference image is registered and a second inspection mode in which a reference image is not registered, at a predetermined timing in the image forming process by the image forming unit 330 of the image to be inspected by the image inspection unit 350.

Description

Technical Field

[0001] The present invention relates to System and image inspection law methods.

Background Art

[0002] Conventionally, a method for inspecting a printed matter by comparing an original image as a reference image with a read image obtained by reading a printed paper (printed matter) on which an inspection image is printed has been known. For example, Patent Document 1 below discloses a printed matter inspection apparatus that inspects the quality of a printed matter by comparing an original image as a reference image with a read image of the printed matter.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the printed matter inspection apparatus of Patent Document 1, it is necessary to complete the generation of the reference image (steps S101 to S115 in FIG. 6) before the generation of the inspection image (step S117 in FIG. 6) is started. Therefore, there is a problem that the processing from the generation of the reference image (steps S101 to S115 in FIG. 6) to the image inspection (steps S117 to S119 in FIG. 6) still requires a considerable amount of time.

[0005] Furthermore, when overprinting—printing based on an original image on top of an already printed sheet of paper—an error may occur if the original image is used as the reference image for inspecting the overprinted material, even if there are no quality issues with the printed material. Therefore, when inspecting overprinted material, it is necessary to register in advance as a reference image the overprinted material that the user has confirmed to be of good quality.

[0006] This invention has been made in view of the above circumstances. This invention provides an image inspection that can improve the productivity of inspection of printed materials by printing without requiring prior registration of a reference image, while also being able to appropriately inspect printed materials by printing that require prior registration of a reference image. System and Imaging examination methods law The purpose is to provide. [Means for solving the problem]

[0007] The above objectives of the present invention are achieved by the following means.

[0008] (1) comprising an image forming unit that forms an image on a recording medium based on acquired image data, a reference image generation unit that generates a reference image used for inspecting the image formed on the recording medium, and an image inspection unit that inspects the image formed on the recording medium based on the reference image, Inspection job At the time of receiving the request, there is a first inspection mode in which the reference image is registered and a second inspection mode in which the reference image is not registered. In the first examination mode, the examination is performed using a first type of reference image, and in the second examination mode, the examination is performed using a second type of reference image that is different from the first type. An image inspection system.

[0009] (2) The image inspection system described in (1) above, wherein the inspection job includes an instruction to the image inspection system to perform an inspection.

[0010] (3) The image inspection system according to (2) above, wherein the inspection job is included in a printing job for forming an image on the recording medium by the image forming unit.

[0011] (4) The image inspection system according to (3) above, wherein the printing job includes a reference image generation job for generating a reference image by the reference image generation unit.

[0012] (5) The second inspection mode is the image inspection system according to (1) or (2) above, wherein the generation of the reference image and the formation of the image on the recording medium are performed in parallel.

[0013] (6) The second inspection mode is the image inspection system according to (1) or (2) above, which performs the generation of the reference image and the inspection of the image in parallel.

[0014] (7) The image inspection system according to (1) or (2) above, wherein, when the second inspection mode is specified, a reference image generation step including the generation of a reference image by the reference image generation unit, and an inspection step including the formation of the image on a recording medium by the image forming unit, and the inspection of a read image generated by reading the recording medium on which the image has been formed, are performed in parallel.

[0015] (8) The reference image registered in the first inspection mode is a read image generated by reading a recording medium on which an image is formed Generated based on , the image inspection system according to the above (1) or (2). (9) The image inspection system according to (1) or (2) above, wherein the first type of reference image is generated based on a read image generated by reading a recording medium on which an image is formed, and the second type of reference image is generated based on an original image.

[0016] ( 10 ) An image inspection method in an image inspection system including an image forming unit that forms an image on a recording medium based on acquired image data, a reference image generation unit that generates a reference image for inspecting the image formed on the recording medium, and an image inspection unit that inspects the image formed on the recording medium based on the reference image, comprising Inspection job At the timing of receiving, having a first inspection mode in which the reference image is registered and a second inspection mode in which the reference image is not registered In the first examination mode, the examination is performed using a first type of reference image, and in the second examination mode, the examination is performed using a second type of reference image that is different from the first type. The image inspection method.

[0017] ( 11 ) The inspection job includes an instruction to the image inspection system to perform the inspection, The image inspection method according to the above ( 10 ).

[0018] ( 12 ) The inspection job is included in a print job for forming an image on the recording medium by the image forming unit, the image inspection method according to the above ( 11 ).

[0019] ( 13 ) The print job includes a reference image generation job for generating a reference image by the reference image generation unit, the image inspection method according to the above ( 12 ).

[0020] ( 14 ) In the second inspection mode, generation of the reference image and formation of an image on the recording medium are performed in parallel, the above ( 10) or the above (11 Image inspection method as described in ).

[0021] ( 15 The second inspection mode involves generating the reference image and inspecting the image in parallel, as described above. 10 )or( 11 Image inspection method as described in ).

[0022] ( 16 )When the second inspection mode is specified, the following are performed in parallel: a reference image generation step including the generation of a reference image by the reference image generation unit, an inspection step including the formation of the image on the recording medium by the image forming unit, and the inspection of the read image generated by reading the recording medium on which the image has been formed by the image inspection unit. 10 )or( 11 Image inspection method as described in ).

[0023] ( 17 The reference image registered in the first inspection mode is a read image generated by reading the recording medium on which the image was formed. Generated based on ,the above( 10 )or( 11 Image inspection method as described in ).

[0024] ( 18 ) The image inspection method according to (10) or (11) above, wherein the first type of reference image is generated based on a read image generated by reading a recording medium on which an image is formed, and the second type of reference image is generated based on an original image. [Effects of the Invention]

[0025] According to the present invention, it is possible to improve the productivity of inspecting printed materials by printing without requiring prior registration of a reference image, while also appropriately inspecting printed materials by printing that require prior registration of a reference image. [Brief explanation of the drawing]

[0026] [Figure 1] This is a schematic block diagram of a printing system according to one embodiment of the present invention. [Figure 2] Figure 1 is a schematic block diagram illustrating the configuration of the image forming system shown. [Figure 3]This is a block diagram illustrating the control operation of the control unit and print controller unit in the process of generating a reference image for the first inspection mode. [Figure 4] This is a block diagram illustrating the general control operation of the control unit and print controller unit in the process of inspecting inspection images in the first inspection mode. [Figure 5] This is a block diagram illustrating the general control operation of the control unit and print controller unit in the second inspection mode. [Figure 6] This is a flowchart illustrating an image inspection method in one embodiment of the present invention. [Figure 7] This is a subroutine flowchart illustrating the execution of the first inspection mode (step S102) in the flowchart shown in Figure 6. [Figure 8] This is the subroutine flowchart following Figure 7. [Figure 9] This is a schematic diagram illustrating the time-series process of acquiring the source image and generating the reference image in the reference image generation process. [Figure 10] This is a schematic diagram illustrating the time-series process of acquiring the original image, forming the inspection image, and inspecting the inspection image in the image formation process. [Figure 11] This is a subroutine flowchart illustrating the execution of the second inspection mode (step S103) in the flowchart shown in Figure 6. [Figure 12] This schematic diagram shows the time-series process of acquiring the original image, generating the reference image, forming the inspection image, and inspecting the inspection image. [Modes for carrying out the invention]

[0027] Embodiments of the present invention will be described below with reference to the attached drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant explanations are omitted. Also, the dimensional ratios in the drawings are exaggerated for illustrative purposes and may differ from the actual ratios.

[0028] <Printing System Configuration> Figure 1 is a schematic block diagram of a printing system according to one embodiment of the present invention, and Figure 2 is a schematic block diagram illustrating the configuration of the image forming system shown in Figure 1.

[0029] As shown in Figure 1, the printing system 100 includes a client terminal 200 and an image forming system 300. The client terminal 200 and the image forming system 300 are connected to each other via a communication line 400 so that they can communicate with one another.

[0030] The client terminal 200 can be, for example, a personal computer, a tablet, or a smartphone. The client terminal 200 has a printer driver installed for converting document data into a print job. The printer driver generates a print job in a format compatible with the print controller unit 320 (see Figure 2) of the image forming system 300 and transmits the print job to the image forming system 300 via the communication line 400. The client terminal 200 also has a display that can show the inspection results of the printed materials (good / defective), images of defective printed materials, etc.

[0031] A print job includes a reference image generation job and an inspection job. The inspection job includes, for example, print data and job information in PDL (Page Description Language) format. The print data includes, for example, data consisting of pages 1 to n. The job information includes, for example, print settings such as the number of pages, number of copies, type of paper (recording medium), size, basis weight, single-sided / double-sided printing, inspection setting (on / off), and print mode. The print mode includes, for example, a normal print mode and an overprinting mode. The user can instruct the image forming system 300 to perform image inspection by turning on the inspection setting.

[0032] Communication line 400 may include a LAN (Local Area Network) connecting computers and network devices according to a predetermined standard, or a WAN (Wide Area Network) connecting LANs with dedicated lines. The predetermined standard is, for example, Ethernet (registered trademark), FDDI (Fiber Distributed Data Interface), Wi-Fi (Wireless Fidelity), etc.

[0033] Note that the number of each of the above-mentioned components connected to the communication line 400 is not limited to the example shown in Figure 1.

[0034] <Configuration of the image forming system 300> As shown in Figures 1 and 2, the image forming system 300 includes a control unit 310, a print controller unit 320, an image forming unit 330, an image reading unit 340, an image inspection unit 350, an operation display unit 360, a paper feeding unit 370, a reference image generation unit 380, and a storage device 390. The image forming system 300 functions as an image inspection device.

[0035] <Configuration of the control unit 310> The control unit 310 includes an image control CPU (Centra Processing Unit) 311, a DRAM (Dynamic Random Access Memory) control IC 312, a memory 313, an image memory (DRAM) 314, a compression / decompression IC 315, a read processing unit 316, a write processing unit 317, a storage unit 318, and the like.

[0036] The image control CPU 311 loads various programs stored in the memory unit 318 into the memory 313 and, in cooperation with the loaded programs, comprehensively controls the operation of the entire image forming system 300.

[0037] The reading processing unit 316 performs various processes such as analog processing, A / D conversion processing, and shading processing on the analog image signal output from the scanner 341 of the image reading unit 340 to generate digital image (read image) data. The generated digital image data is then output to the compression / decompression IC 315 by the DRAM control IC 312. The compression / decompression IC 315 performs compression processing on the digital image data and decompression processing on the digital image data after compression processing based on the control of the DRAM control IC 312. The DRAM control IC 312 also controls the input / output of the image memory (DRAM) 314 for the compressed / decompressed digital image data.

[0038] The image memory 314 is composed of DRAM and includes compressed memory and page memory areas internally, for temporarily storing compressed image data, decompressed image data, etc.

[0039] The writing processing unit 317 outputs the decompressed digital image data to the exposure unit 332 of the image forming unit 330.

[0040] <Configuration of the print controller unit 320> The print controller unit 320 analyzes the print job received from the client terminal 200 via the communication line 400, performs processing such as color conversion, screening, and rasterization, and generates a bitmap-formatted original image. The generated original image is transmitted to the control unit 310. The print controller unit 320 functions as an original image acquisition unit.

[0041] The print controller unit 320 comprises a controller control unit 321, a DRAM control IC 322, an image memory (DRAM) 323, a communication control unit 324, a communication interface 325, and the like. The controller control unit 321 comprehensively controls the operation of each part of the print controller unit 320. The controller control unit 321 also receives print jobs from client terminals 200, etc., via the communication interface 326. The communication control unit 324 controls the communication interface 325.

[0042] A received print job includes print data (mainly in PDL format) that forms the basis of the original image, and job information that describes print settings such as the type of paper to be used. The print controller unit 320 performs rasterization (RIP) processing to convert the print data into page-level bitmap data based on the print settings. The RIP image after rasterization is temporarily stored in the image memory 323. The RIP image in the image memory 323 is temporarily stored in the compressed memory area of ​​the image memory 314 via the compression / decompression IC 315, under the control of the DRAM control IC 322 of the print controller unit 320 and the DRAM control IC 312 of the control unit 310. During normal printing, the RIP image stored in the compressed memory area is decompressed by the compression / decompression IC 315 and sent to the image forming unit 330 as the original image (image data) via the writing processing unit 317, where printing is performed.

[0043] The control unit 310 outputs a reference image generation instruction to the reference image generation unit 380 (described later) at a predetermined generation timing to generate a reference image based on the original image. The reference image generation unit 380 generates a reference image based on the reference image generation instruction.

[0044] Ideally, the scanned image generated by reading the inspection image formed on the paper should match the original image in terms of content. However, when scanning the inspection image formed on the paper, errors may occur in the scanned image compared to the original image due to various factors such as variations in the paper transport path, deviations in the scanning position, color reproduction, and differences in paper type. Errors may also occur depending on the resolution of the scanner. Therefore, simply comparing the scanned image with the original image is likely to result in errors, and it is not practical to inspect the inspection image by simply comparing the scanned image with the original image. In this embodiment, various processes are applied to the original image regarding position, resolution, color, etc., to generate a reference image that can be compared with the scanned image, and the system is configured to compare the reference image with the scanned image. This ensures that the comparison with the scanned image is performed appropriately, allowing for accurate inspection of printed materials. Details of the reference image generation process will be described later.

[0045] <Configuration of the image forming unit 330> The image forming unit 330 forms (prints) an image on paper using an electrophotographic method that includes the steps of charging, exposure, development, transfer, and fixing, according to the instructions of the control unit 310. In this embodiment, the image forming unit 330 forms an inspection image on the paper according to the image forming conditions set based on the print settings, which is to be inspected by the image inspection unit 350. The image forming unit 330 includes a printer control unit 331 and an exposure unit 332, etc. The printer control unit 331 is connected to the image control CPU 311 by serial communication and accepts control from the image control CPU 311. The printer control unit 331 drives the LD (Laser Diode) of the exposure unit 332 by a signal from the writing processing unit 317 to form an electrostatic latent image corresponding to the original image on the photoreceptor (not shown). The toner image formed on the photoreceptor is developed through the development process and transferred onto the paper supplied from the paper feeding unit 370. The unfixed toner image on the paper is then fixed by heating and pressurizing. The paper on which the toner image has been fixed is transported to the image reading unit 340.

[0046] Furthermore, the image forming unit 330 is equipped with a print sheet output device that separates and outputs (purges) sheets on which an abnormal inspection image has been detected by the image inspection unit 350 (waste paper) from sheets on which a normal inspection image has been formed.

[0047] <Configuration of the image reading unit 340> The image reading unit 340 includes a scanner 341 and a scanner control unit 342. The scanner 341 reads the paper (printed material) being transported along the transport path, for example, using a CCD (Charge Coupled Device) image sensor. The scanner control unit 342 controls the scanner to read the inspection image formed on the paper transported from the image forming unit 330, according to the reading instructions from the control unit 310. The scanner control unit 342 outputs the read image, which is the inspection image formed on the paper, to the control unit 310.

[0048] <Configuration of the Image Inspection Unit 350> The image inspection unit 350 performs image inspection based on a reference image. More specifically, the image inspection unit 350 acquires a reference image and a read image, and inspects the inspection image formed on the paper by comparing the reference image and the read image page by page.

[0049] The image inspection unit 350 includes an image inspection control unit 351. The image inspection control unit 351 includes an image control CPU 311, or a CPU (not shown), RAM, ROM, and auxiliary storage device. The function of inspecting the inspection image is realized by the CPU executing an image inspection program. The image inspection control unit 351 calculates, for example, the difference (error) of pixel values ​​between a reference image and a read image for each page, and determines whether the inspection image is good or bad according to the size of the difference. The difference calculation can be performed for each page, each object, or each region. For example, when the difference is calculated for each page, if the total difference of pixels within a page is less than a specified value, an inspection result of "good" is output, and if the total difference is equal to or greater than the specified value, an inspection result of "bad" is output. Also, when the difference is calculated for each object or region, the system can be configured to output an inspection result of "good" or "bad" according to the total difference of pixel values ​​within the selected object or region.

[0050] The control unit 310 determines that the printed material is a good product if the inspection result of the inspection image is "good," and determines that the printed material is a defective product if the inspection result of the inspection image is "poor."

[0051] <Configuration of the operation display unit 360> The operation display unit 360 includes a touch panel display 361, an operation control unit 362, and hard keys such as a numeric keypad, start button, stop button, etc. The touch panel display includes, for example, a touch sensor and an LCD (Liquid Crystal Display) located behind the touch sensor. The operation control unit 362 receives input from the touch sensor and hard keys and transmits the input data to the control unit 310. The operation control unit 362 also receives output data from the control unit 310 and displays it on the LCD. The operation display unit 360 is used for inputting various settings by the user (e.g., turning inspection settings on / off) and instructions (e.g., instructions to start printing). The operation display unit 360 is also used for outputting (displaying) the status of the image forming system 300, the inspection results of printed materials (good / defective), images of defective printed materials, etc.

[0052] <Configuration of the paper feeding unit 370> The paper feeding unit 370 is equipped with at least one large-capacity paper tray and supplies paper to the image forming unit 330 one sheet at a time.

[0053] <Configuration of the reference image generation unit 380> The reference image generation unit 380 generates a reference image based on the original image acquired by the original image acquisition unit and outputs it to the control unit 310. The reference image generation unit 380 can be implemented by having a separate CPU (not shown) execute an image inspection program, separate from the image control CPU 311. This allows the generation of the reference image and the formation and inspection of the inspection image to be performed in parallel in the second inspection mode described later. Alternatively, if the image control CPU 311 is a multi-core CPU, the reference image generation unit 380 may be assigned to a separate core from the inspection image formation and inspection processes, and the generation of the reference image and the formation and inspection of the inspection image may be performed in parallel by separate cores.

[0054] Conventionally, the generation of reference images and the formation and inspection of inspection images were performed by the same CPU. Therefore, the CPU performed the formation and inspection of inspection images only after the generation of reference images was completed for each page, making it impossible to perform the generation of reference images and the formation and inspection of inspection images in parallel. In this embodiment, the generation of reference images and the formation and inspection of inspection images are performed by separate CPUs, so the generation of reference images and the formation and inspection of inspection images can be performed in parallel.

[0055] Furthermore, if the source image is complex, the computational load for generating the reference image may increase significantly. By having a separate CPU handle the generation of the reference image, the computational load on the image control CPU 311 can be reduced.

[0056] <Configuration of storage device 390> The storage device 390 stores the reference image generated by the reference image generation unit 380. When the control unit 310 reprints the original image, it uses the reference image stored in the storage device 390, eliminating the need to generate the reference image again. Therefore, the time required to generate the reference image can be saved.

[0057] <Overview of the control operation of the control unit 310 and the print controller unit 320> [Generating and registering reference images] As described above, the reference image generation unit 380 generates a reference image for each page based on the original image. The control unit 310 registers the reference images whose quality has been confirmed by the user as reference images to be used for inspecting the inspection images. Note that the quality confirmation of the reference images can be omitted as appropriate according to the user's instructions, and the generated reference images can be registered immediately.

[0058] In this case, the generation of the reference image only needs to be completed before the inspection of the printed material to be inspected begins. For example, when the control unit 310 generates a reference image based on the original image of a reprinted printed material, it controls the reference image generation unit 380 to generate the reference image from the time the reference image generation job is acquired until the image of the printed material to be inspected is formed on the printed paper.

[0059] When generating a reference image based on an original image, the generation of the reference image begins when a reference image generation job is acquired. Alternatively, the system may be configured to receive user instructions via the operation display unit 360 and adjust the start timing of the reference image generation.

[0060] Alternatively, instead of generating a reference image using the reference image generation unit 380, the device may be configured to pre-store images in the storage device 390 and register them as reference images according to user instructions.

[0061] [Inspection Mode] The image forming system 300 has multiple inspection modes, including a first inspection mode and a second inspection mode. The first inspection mode is an inspection mode in which a reference image is registered at a predetermined timing in the image forming process by the image forming unit 330 of the inspection image to be inspected by the image inspection unit 350. On the other hand, the second inspection mode is an inspection mode in which a reference image is not registered at a predetermined timing. The control unit 310 is configured to execute any of the multiple inspection modes, including the first inspection mode and the second inspection mode. For example, the user can set the print mode to overprint mode or normal mode through the print settings of the job information. If overprint mode is set, the control unit 310 specifies (selects) the first inspection mode, and if normal mode is set, it specifies the second inspection mode.

[0062] The image formation process is performed between the acquisition of the print job (inspection job) and the formation of the inspection image on the paper by the image forming unit 330 based on the original image. The predetermined timing may include the timing of the acquisition of the inspection job. Furthermore, the predetermined timing may include the timing of the start of image formation by the image forming unit 330, or the timing during image formation. If the original image includes an image of multiple pages, the predetermined timing may include the timing during image formation for at least the first page of the inspection image (see, for example, Figures 10 and 12).

[0063] In the first inspection mode, the image inspection unit 350 inspects the printed material to be inspected using a reference image that has been confirmed for quality by the user and registered from among the reference images generated by the reference image generation unit 380. Alternatively, the control unit 310 registers an image that has been previously confirmed for quality by the user from among the images stored in the storage device 390 as a reference image, and the image inspection unit 350 inspects the printed material to be inspected using the registered reference image. For example, the control unit 310 registers a read image that has been confirmed for quality by the user as a reference image from among multiple read images generated by reading a printed material that has been overprinted on already printed paper. The image inspection unit 350 inspects the overprinted printed material to be inspected using the registered reference image. This prevents errors from occurring when inspecting overprinted printed material, even if there are no problems with the quality of the printed material, by using the original image as the reference image.

[0064] On the other hand, in the second inspection mode, the reference image is not registered at the predetermined timing described above. The reference image is registered before the inspection of the inspection image begins. In the second inspection mode, the control unit 310 controls the reference image generation unit 380 and the image forming unit 330 to perform the generation of the reference image and the formation of the inspection image on the paper in parallel. More specifically, the control unit 310 causes the reference image generation process and the inspection process to be executed in parallel. The reference image generation process includes the generation of a reference image by the reference image generation unit 380 when the second inspection mode is specified as the inspection mode. The inspection process includes the formation of an inspection image on the paper by the image forming unit 330 and the inspection of the read image generated by reading the paper on which the inspection image has been formed by the image inspection unit 350. This shortens the time required for processing from the generation of the reference image to the image inspection. As a result, the productivity of printed materials is improved.

[0065] Thus, in this embodiment, at the predetermined timing described above, the first inspection mode or the second inspection mode can be identified depending on whether or not a reference image has been registered. As described above, the printing mode includes a normal printing mode and a co-printing mode. When the co-printing mode is selected, a reference image has been registered. For example, depending on whether or not the printing requires prior registration of a reference image, i.e., registration of a reference image before the execution of the image forming process, such as in co-printing, the control unit 310 executes either the first inspection mode or the second inspection mode. For example, the system may be configured such that the first inspection mode is executed when the printing mode is the co-printing mode, while the second inspection mode is executed when the printing mode is not the co-printing mode.

[0066] Furthermore, in this embodiment, the control unit 310 may be configured to execute the first inspection mode when a reference image of the quality desired by the user is registered in advance. This ensures that the user's requirements regarding the quality of the reference image are reliably reflected.

[0067] The following describes the general control operations of the control unit 310 and the print controller unit 320 in the first and second inspection modes, respectively.

[0068] [First Inspection Mode] The inspection using the first inspection mode consists of two steps: generating a reference image and inspecting the inspection image. Each of these steps will be described in detail below.

[0069] (Process for generating a reference image) Figure 3 is a block diagram illustrating the control operation of the control unit 310 and the print controller unit 320 in the process of generating a reference image for the first inspection mode.

[0070] First, the control unit 310 receives the original image and job information from the original image acquisition unit (print controller unit 320) ((1)-1 Image Input). The original image is a RIP image obtained by rasterizing the print data. The control unit 310 stores the original image input by the original image acquisition unit in page memory 1.

[0071] Next, the control unit 310 outputs the original image from the page memory 1 to the image forming unit 330 ((2)-1 Image output), and the image forming unit 330 forms an image on the paper (printed paper) based on the original image. After the paper has been ejected, the image forming unit 330 notifies the control unit 310 that the paper has been ejected ((3)-1 Output completion).

[0072] Next, the control unit 310 instructs the image reading unit 340 to read the image formed by the image forming unit 330 ((4)-1 Image reading instruction). The image reading unit 340 reads the image formed by the image forming unit 330, saves the read image to the page memory 2, and notifies the control unit 310 that the reading is complete ((5)-1 Image reading completion).

[0073] When the reference image generation unit 380 receives a reference image generation instruction from the control unit 310 ((6)-1 Reference Image Generation Instruction), it generates a reference image based on the read image stored in the page memory 2 and outputs it to the control unit 310. The control unit 310 saves the reference image in the page memory 1. After generating the reference image, the reference image generation unit 380 notifies the control unit 310 that the generation of the reference image is complete ((7)-1 Reference Image Generation Complete). The control unit 310 also saves the reference image stored in the page memory 1 to the storage device 390 ((8)-1 Reference Image Saving).

[0074] The control unit 310 repeats the processes described in (1)-1 to (8)-1 above until the generation of reference images is completed for all pages of the printed material to be inspected.

[0075] As described above, the reference image generation unit 380 generates a reference image by performing various processes on the reference image regarding its position, resolution, color, etc. For example, the reference image generation unit 380 can extract positional information of the content portion from the original image and add or embed this positional information into the reference image so that the content portions of the reference image and the read image can be compared. In other words, the reference image generated by the reference image generation unit 380 has alignment information for aligning the reference image and the read image when performing image inspection based on the reference image. This alignment information includes image contour information and edge information. Furthermore, the reference image generated by the reference image generation unit 380 has area information regarding the inspection area and inspection exclusion area used when performing image inspection based on the reference image. In addition, the reference image generation unit 380 can generate a reference image by adjusting the resolution of the original image to match the resolution of the scanner of the image reading unit 340. Furthermore, the reference image generation unit 380 can generate a reference image by converting the color space of the original image to match the color space (for example, RGB) used by the scanner of the image reading unit 340.

[0076] (The process of inspecting the inspection images) Figure 4 is a block diagram illustrating the control operation of the control unit 310 and the print controller unit 320 in the process of inspecting the inspection image in the first inspection mode.

[0077] First, the control unit 310 receives the original image and job information from the original image acquisition unit ((1)-2 Image Input). The original image is a RIP image obtained by rasterizing the print data. The control unit 310 stores the original image input from the original image acquisition unit in page memory 1.

[0078] Next, the control unit 310 outputs the original image from the page memory 1 to the image forming unit 330 ((2)-2 Image Output), and the image forming unit 330 forms an image on the paper (printed paper) based on the original image. After the paper has been ejected, the image forming unit 330 notifies the control unit 310 that the paper has been ejected ((3)-2 Output Completion).

[0079] Next, the control unit 310 instructs the image reading unit 340 to read the image formed by the image forming unit 330 ((4)-2 Reading instruction). The image reading unit 340 reads the image formed by the image forming unit 330, saves the read image to the page memory 2, and notifies the control unit 310 that the reading is complete ((5)-2 Reading completion).

[0080] Next, the control unit 310 instructs the storage device 390 to read the reference image ((6)-2 Reading the reference image), and reads the reference image from the storage device 390 into the page memory 1.

[0081] Next, the control unit 310 instructs the image inspection unit 350 to perform an image inspection ((7)-2 Image Inspection Instruction). The image inspection unit 350 acquires a reference image and a read image from page memory 1 and page memory 2, respectively, and inspects the inspection image by comparing the reference image and the read image. The image inspection unit 350 then notifies the control unit 310 of the inspection result of the inspection image ((8)-2 Image Inspection Result).

[0082] The control unit 310 repeats the processes described in (1)-2 to (8)-2 above until the inspection is completed for all pages of the printed material to be inspected.

[0083] The control unit 310, in response to user instructions, controls the display of the inspection results (good / defective) of the printed material based on the inspection results of the inspection image, on the display of the operation display unit 360 or the client terminal 200.

[0084] [Second Inspection Mode] Figure 5 is a block diagram illustrating the control operation of the control unit 310 and the print controller unit 320 in the second inspection mode.

[0085] First, the control unit 310 receives the original image and job information from the original image acquisition unit ((1)-3 Image Input). The original image is a RIP image obtained by rasterizing the print data. The control unit 310 stores the original image input from the original image acquisition unit in page memory 1.

[0086] When the reference image generation unit 380 receives a reference image generation instruction from the control unit 310 ((2)-3 Reference Image Generation Instruction), it generates a reference image based on the original image acquired by the original image acquisition unit and outputs it to the control unit 310. The control unit 310 saves the reference image in the page memory 1. As described above, the reference image generation unit 380 generates a reference image by performing various processes on the original image regarding position, resolution, color, etc.

[0087] Furthermore, when the control unit 310 receives a document image from the document image acquisition unit, it instructs the image forming unit 330 to form an image and outputs the document image stored in page memory 1 to the image forming unit 330 ((2)-3 Image Output). In this embodiment, the image forming unit 330 forms an inspection image on the paper based on the document image. The generation of the reference image by the reference image generation unit 380 and the formation of the inspection image by the image forming unit 330 are performed in parallel.

[0088] When the reference image generation unit 380 has finished generating the reference image, it notifies the control unit 310 that the reference image generation is complete ((3)-3 Reference image generation complete). Also, when the image forming unit 330 has finished forming the image on the paper, it notifies the control unit 310 that the output is complete ((3)-3 Output complete). The storage device 390 saves the generated reference image ((4)-3 Reference image save).

[0089] Furthermore, as soon as the control unit 310 receives notification of output completion, it outputs an image reading instruction to the image reading unit 340 ((4)-3 Image Reading Instruction). The image reading unit 340 reads the paper on which the inspection image has been formed and outputs the read image of the paper to the control unit 310. The control unit 310 saves the read image in the page memory 2. When the image reading unit 340 has finished reading the paper, it notifies that the image reading is complete ((5)-3 Image Reading Complete).

[0090] Upon receiving notification that image reading is complete, the control unit 310 outputs an image inspection instruction to the image inspection unit 350 ((6)-3 Image Inspection Instruction). The image inspection unit 350 acquires a reference image and a read image from page memory 1 and page memory 2, respectively, and inspects the inspection image by comparing the reference image and the read image. The image inspection unit 350 then outputs the inspection result of the inspection image to the control unit 310 ((7)-3 Image Inspection Result).

[0091] The control unit 310 repeats the processes described in (1)-3 to (7)-3 above until the inspection is completed for all pages of the printed material to be inspected.

[0092] The control unit 310, in response to user instructions, controls the display of the inspection results (good / defective) of the printed material based on the inspection results of the inspection image, on the display of the operation display unit 360 or the client terminal 200.

[0093] <Image inspection method using image forming system 300> Figure 6 is a flowchart illustrating the processing procedure of the image inspection method using the image forming system 300 shown in Figure 1. The processing shown in Figure 6 is realized by the image control CPU 311 executing the image inspection program. In the following, the case where prior registration of a reference image is required will be explained using the example of the overprinting mode.

[0094] First, when a print job is started, the control unit 310 determines whether the print mode is overprint mode or not (step S101). If the print mode is overprint mode (step S101: YES), the control unit 310 executes the first inspection mode. On the other hand, if the print mode is not overprint mode (step S101: NO), the control unit 310 executes the second inspection mode.

[0095] In the above, the system determined whether the inspection mode to be executed was the first inspection mode or the second inspection mode based on the selected print mode. However, it is also possible to accept a user's specification of the inspection mode and then determine whether the accepted inspection mode is the first inspection mode or the second inspection mode.

[0096] [First Inspection Mode] Figure 7 is a subroutine flowchart illustrating the details of the execution process (step S102) of the first inspection mode in the flowchart shown in Figure 6. Figure 8 is a subroutine flowchart following Figure 7. The processes shown in Figures 7 and 8 are realized by the image control CPU 311 executing the image inspection program. Figure 9 is a schematic diagram showing the processes of acquiring the original image and generating the reference image in the reference image generation process in chronological order. Figure 10 is a schematic diagram showing the processes of acquiring the original image, forming the inspection image, and inspecting the inspection image in the image formation process in chronological order.

[0097] As shown in Figure 7, first, the control unit 310 acquires the original document image (step S201). The control unit 310 receives the original document image (RIP image) from the original document image acquisition unit, one page at a time, from the first page to the final nth page. For example, Figure 9 illustrates the case where the original document image is received sequentially from the first page to the eighth page. In Figures 9, 10, and 12, "1P" represents the first page (and similarly for "2P," etc.). The generation time of the reference image may vary from page to page depending on the number of inspection areas and / or inspection exclusion areas, inspection settings, etc. Factors that cause the generation time of the reference image to vary from page to page include, for example, the complexity of the content. Figure 9 shows an example where it took time to generate the reference image for the second page.

[0098] Next, the control unit 310 saves the original image (step S202). When a print job is started, the control unit 310 saves the original image acquired from the original image acquisition unit to the page memory 1 one page at a time.

[0099] Next, the control unit 310 prints an image based on the original image (step S203). Based on the original image and job information received from the original image acquisition unit, the control unit 310 controls the image forming unit 330 to form an image on the paper (printed paper). For example, the control unit 310 performs "print preparation" and controls the image forming unit 330 to form an inspection image on the paper for the first page of the original image. The image forming unit 330 forms an image on the paper for the first page of the original image according to the instructions of the control unit 310. After the image for the first page of the original image is formed on the paper, an image is similarly formed on the paper for the second page of the original image. Note that "print preparation" includes initial settings and preparations of each part of the image forming unit 330 according to the image forming conditions (for example, warming up the fuser unit).

[0100] Next, the image reading unit 340 reads the image formed on the printing paper (step S204) and transmits it to the control unit 310 as the read image. The control unit 310 stores the read image received from the image reading unit 340 in the page memory 2.

[0101] Next, the reference image generation unit 380 generates a reference image (step S205). It generates a reference image to be used for inspecting the inspection image according to the instructions of the control unit 310. As shown in Figure 9, for example, if the first page of the original image has been acquired and stored in page memory 1, the control unit 310 controls the reference image generation unit 380 to generate a reference image based on the first page of the original image. The reference image generation unit 380 generates a reference image based on the first page of the original image. A reference image is similarly generated for the second page of the original image.

[0102] Next, the storage device 390 stores the reference image generated by the reference image generation unit 380 (step S206). For example, the storage device 390 stores the first and second pages of the original image.

[0103] Next, the control unit 310 determines whether or not all pages have been acquired (step S207). If the control unit 310 has not acquired images of all pages of the printed material to be inspected (step S207: NO), it proceeds to the process in step S201.

[0104] On the other hand, if the control unit 310 has acquired images for all pages of the original document (step S207: YES), it proceeds to the process shown in step S208 of Figure 8.

[0105] As shown in Figure 8, the control unit 310 acquires the original image (step S208). The original image is the image to be formed on the printed paper for overprinting.

[0106] Next, the control unit 310 saves the original document image (step S209). The control unit 310 saves the original document image acquired from the original document image acquisition unit to the page memory 1, one page at a time.

[0107] Next, the control unit 310 reads out the reference image (step S210). The control unit 310 reads out the reference image stored in the page memory 1 and outputs it to the image inspection unit 350.

[0108] Next, the image forming unit 330 prints an image based on the original image (step S211). The control unit 310 controls the image forming unit 330 to form an inspection image on the paper (printed paper) based on the original image and job information received from the original image acquisition unit. For example, the control unit 310 prepares for printing and controls the image forming unit 330 to form an inspection image on the paper for the original image on the first page. The image forming unit 330 forms an inspection image on the paper for the first page of the original image according to the instructions of the control unit 310. After the inspection image is formed based on the original image on the first page, an inspection image is similarly formed on the paper for the original image on the second page.

[0109] Next, the image reading unit 340 reads the inspection image formed on the paper (step S212) and transmits it to the control unit 310 as a read image. The control unit 310 stores the read image received from the image reading unit 340 in the page memory 2.

[0110] Next, the image inspection unit 350 inspects the inspection image by comparing the reference image stored in page memory 1 with the read image stored in page memory 2 (step S213).

[0111] Next, the control unit 310 determines whether or not it has acquired images of all pages of the printed material to be inspected (step S214). If the control unit 310 has not acquired images of all pages (step S214: NO), it proceeds to the process in step S208. On the other hand, if the control unit 310 has acquired images of all pages (step S214: YES), it terminates the process (return).

[0112] As described above, in the first inspection mode, the reference image is registered at the predetermined timing. As shown in Figure 10, the predetermined timing may include the timing of acquiring the inspection job. The predetermined timing may also include the timing of the start of image formation of the inspection job by the image forming unit 330, or the timing during image formation of the inspection job. If the original image includes an image with multiple pages, the predetermined timing may include the timing during image formation for at least the first page of the inspection image.

[0113] In the example described above, we mainly explained the case where a reference image generated based on the original image is created and registered. However, it is not limited to this case; based on user instructions, for example, an image pre-stored in the storage device 390 can also be registered as the reference image.

[0114] [Second Inspection Mode] Figure 11 is a flowchart illustrating the processing procedure of the image inspection method by the image forming system 300 in the second inspection mode. The processing shown in Figure 11 is realized by the image control CPU 311 executing the image inspection program. Figure 12 is a schematic diagram showing the processes of acquiring the original image, generating the reference image, forming the inspection image, and inspecting the inspection image in chronological order.

[0115] As shown in Figure 11, first, the control unit 310 acquires the original document image (step S301). The control unit 310 receives the original document image (RIP image) from the original document image acquisition unit, one page at a time, from the first page to the final nth page. For example, Figure 12 illustrates the case where the original document image is received sequentially from the first page to the eighth page.

[0116] Next, the control unit 310 saves the original image (step S302). When a print job is started, the control unit 310 saves the original image acquired from the original image acquisition unit to the page memory 1 one page at a time.

[0117] Next, the control unit 310 controls the generation of reference images used for inspecting the inspection images. The reference image generation unit 380 generates reference images according to the instructions of the control unit 310 (step S303). For example, if the first page of the original image has been acquired and stored in page memory 1, the control unit 310 controls the reference image generation unit 380 to generate a reference image based on the first page of the original image. The reference image generation unit 380 generates a reference image based on the first page of the original image. A reference image is similarly generated for the second page of the original image.

[0118] Next, the storage device 390 stores the reference image generated by the reference image generation unit 380 (step S304). For example, the storage device 390 stores the first and second pages of the original image. In this embodiment, as shown in Figure 11, the control unit 310 controls the image forming unit 330 to form an inspection image on the paper based on the original image and job information received from the original image acquisition unit, in parallel with the processing in steps S303 and S304. For example, the control unit 310 prepares for printing and controls the image forming unit 330 to form an inspection image on the paper for the first page of the original image. The image forming unit 330 forms an inspection image on the paper for the first page of the original image according to the instructions of the control unit 310 (step S305). After the inspection image for the first page of the original image is formed, an inspection image is similarly formed on the paper for the second page of the original image.

[0119] Next, the inspection image formed on the paper is read (step S306).

[0120] Next, the image inspection unit 350 determines whether a reference image has been generated for each page of the acquired original image (step S307). If the reference image has been generated (step S307: YES), the image inspection unit 350 compares the reference image with the read image to inspect the inspection image (step S308).

[0121] The control unit 310 repeats the process in steps S301 to S308 for all pages (from the first page to the final nth page) until the inspection of the inspection images is completed (step S309).

[0122] On the other hand, if a reference image has not been generated (step S307: NO), the image inspection unit 350 waits until a reference image is generated. For example, if a reference image of the same original image (page 1) that will be used as the basis for the inspection image to be inspected in step S308 has not been generated, the unit waits until a reference image of this original image (page 1) is generated.

[0123] As described above, in the second inspection mode, the reference image is not registered at the predetermined timing. As shown in Figure 12, the predetermined timing may include the timing of acquiring the print job. The predetermined timing may also include the timing of the start of image formation of the print job by the image forming unit 330, or the timing during image formation of the print job. In the second inspection mode, the reference image may not be registered at the predetermined timing.

[0124] As shown in Figure 11, the generation of a reference image by the reference image generation unit 380 and the formation of an inspection image by the image forming unit 330, as well as the inspection of the inspection image, are performed in parallel. As a result, the image forming system 300 can further reduce the time required for processing from the generation of a reference image to image inspection compared to conventional technology.

[0125] [Generating reference images and forming inspection images on paper in parallel] For example, in the example shown in Figure 12, the generation of reference images for page 1 (1P) and page 2 (2P) and the preparation for printing are performed in parallel, and the generation of the reference image for page 3 (3P) and the formation of the first half of the inspection image for page 1 (1P) are performed in parallel. Then, the generation of the reference image for page 4 (4P) and the formation of the second half of the inspection image for page 1 (1P) are performed in parallel. Note that although the figure shows the generation of the reference image for page 3 (3P) and the formation of the inspection image for page 1 (1P) starting simultaneously, this is not the only option. The formation of the inspection image for page 1 (1P) can start at an appropriate time after the preparation for printing is complete, and the generation of the reference image for page 3 (3P) can start at an appropriate time after the generation of the reference image for page 2 (2P). The timing for starting the generation of reference images and inspection images is the same for subsequent pages.

[0126] [Generating reference images, forming inspection images on paper, and inspecting the inspection images in parallel] Subsequently, the generation of the reference image on page 5 (5P), the formation of the examination image on page 2 (2P), and the examination of the examination image on page 1 are performed in parallel.

[0127] In this embodiment, based on the reception of the original image (starting from the reception of the original image), a reference image is generated, and when the paper is ready for printing, an inspection image is formed and the inspection image is inspected. In this embodiment, the generation of the reference image and the formation and inspection of the inspection image are performed in parallel, so the time required for processing from the generation of the reference image to image inspection can be shortened. As a result, the productivity of printed materials is improved.

[0128] The image inspection apparatus of this embodiment described above provides the following effects.

[0129] This method improves the productivity of inspecting printed materials using printing methods that do not require prior registration of reference images, while also enabling proper inspection of printed materials that do require prior registration of reference images.

[0130] As described above, the image inspection apparatus, image inspection method, and image inspection program have been explained in the embodiments. However, it goes without saying that the present invention can be appropriately added to, modified, and omitted by those skilled in the art within the scope of its technical concept.

[0131] For example, the above-described embodiment described a case in which an original image is generated based on a print job, but the present invention is not limited to such a case. The image forming unit 330 may have an image reading device 333 (see Figure 1) that reads an original document prepared by the user, and may be configured to generate an original image based on the image generated by reading the original document with the image reading device 333. The image reading device 333, for example, reads an original document that has been transported to a predetermined reading position by an automatic document transport device using a scanner and generates image data.

[0132] Furthermore, the image inspection program may be provided on a computer-readable recording medium such as a USB memory stick, flexible disk, or CD-ROM, or it may be provided online via a network such as the Internet. In this case, the program recorded on the computer-readable recording medium is usually transferred to memory or storage and stored therein. This inspection program may also be provided, for example, as a standalone application software, or it may be incorporated into the software of each device as a function of a server.

[0133] Furthermore, in the embodiment, some or all of the processing performed by the inspection program may be replaced and executed by hardware such as circuits. [Explanation of symbols]

[0134] 100 printing systems, 200 client terminals, 300 image forming systems, 310 Control unit, 311 Image control CPU, 312 DRAM control IC, 313 memory, 314 Image memory (DRAM), 315 Compression / Decompression IC, 316 Reading processing unit, 317 Writing processing unit, 318 Memory section, 320 Print Controller Section, 321 Controller control unit, 322 DRAM control IC, 323 Image memory (DRAM), 324 Communication Control Unit, 325 Communication I / F, 330 Image forming unit, 331 Printer control unit, 332 Exposure section, 333 Image reading device, 340 Image reading unit, 341 Scanners, 342 Scanner control unit, 350 Image Inspection Department, 351 Image inspection control unit, 360 operation display section, 361 LCD / touch sensor, 362 Operation control unit, 370 Paper feed section, 380 Reference image generation unit, 390 storage device, 400 communication lines.

Claims

1. An image forming unit that forms an image on a recording medium based on acquired image data, A reference image generation unit that generates a reference image used for inspecting the image formed on the recording medium, The system includes an image inspection unit that inspects an image formed on the recording medium based on the aforementioned reference image, At the time an inspection job is received, the system has a first inspection mode in which the reference image is registered and a second inspection mode in which the reference image is not registered. An image inspection system that performs inspection using a first type of reference image in the first inspection mode, and performs inspection using a second type of reference image different from the first type in the second inspection mode.

2. The image inspection system according to claim 1, wherein the inspection job includes an instruction to the image inspection system to perform an inspection.

3. The image inspection system according to claim 2, wherein the inspection job is included in a printing job for forming an image on the recording medium by the image forming unit.

4. The image inspection system according to claim 3, wherein the printing job includes a reference image generation job for generating a reference image by the reference image generation unit.

5. The image inspection system according to claim 1 or 2, wherein the second inspection mode performs the generation of the reference image and the formation of the image on the recording medium in parallel.

6. The image inspection system according to claim 1 or 2, wherein the second inspection mode performs the generation of the reference image and the inspection of the image in parallel.

7. The image inspection system according to claim 1 or 2, wherein, when the second inspection mode is specified, a reference image generation step including the generation of a reference image by the reference image generation unit, and an inspection step including the formation of the image on a recording medium by the image forming unit, and the inspection of a read image generated by reading the recording medium on which the image has been formed, are performed in parallel.

8. The image inspection system according to claim 1 or 2, wherein the reference image registered in the first inspection mode is generated based on a read image generated by reading a recording medium on which an image has been formed.

9. The image inspection system according to claim 1 or 2, wherein the first type of reference image is generated based on a read image generated by reading a recording medium on which an image is formed, and the second type of reference image is generated based on an original image.

10. An image inspection method in an image inspection system comprising: an image forming unit that forms an image on a recording medium based on acquired image data; a reference image generation unit that generates a reference image used for inspecting the image formed on the recording medium; and an image inspection unit that inspects the image formed on the recording medium based on the reference image, At the time an inspection job is received, the system has a first inspection mode in which the reference image is registered and a second inspection mode in which the reference image is not registered. An image inspection method comprising: performing an inspection using a first type of reference image in the first inspection mode; and performing an inspection using a second type of reference image different from the first type in the second inspection mode.

11. The image inspection method according to claim 10, wherein the inspection job includes an instruction to the image inspection system to perform an inspection.

12. The image inspection method according to claim 11, wherein the inspection job is included in a printing job for forming an image on the recording medium by the image forming unit.

13. The image inspection method according to claim 12, wherein the printing job includes a reference image generation job for generating a reference image by the reference image generation unit.

14. The image inspection method according to claim 10 or 11, wherein the second inspection mode is performed in parallel with the generation of the reference image and the formation of the image on the recording medium.

15. The image inspection method according to claim 10 or 11, wherein the second inspection mode performs the generation of the reference image and the inspection of the image in parallel.

16. The image inspection method according to claim 10 or 11, wherein, when the second inspection mode is specified, a reference image generation step including the generation of a reference image by the reference image generation unit, an inspection step including the formation of the image on a recording medium by the image forming unit, and the inspection of a read image generated by reading the recording medium on which the image has been formed by the image inspection unit are performed in parallel.

17. The image inspection method according to claim 10 or 11, wherein the reference image registered in the first inspection mode is generated based on a read image generated by reading a recording medium on which an image has been formed.

18. The image inspection method according to claim 10 or 11, wherein the first type of reference image is generated based on a read image generated by reading a recording medium on which an image is formed, and the second type of reference image is generated based on an original image.

Images