Image inspection device, image inspection method and image inspection program

Abstract

To provide an image inspection device, an image inspection method and an image inspection program which can properly inspect a printed matter by printing requiring a reference image to be pre-registered, while improving productivity in inspecting a printed matter by printing not requiring the reference image to be pre-registered.SOLUTION: An image inspection device 300 comprises an image formation part 330, a reference image generation part 380, and an image inspection part 350. The image formation part 330 forms an image on a recording medium on the basis of obtained image data. The reference image generation part 380 generates a reference image that is used in inspecting the image formed on the recording medium. The image inspection part 350 inspects the image formed on the recording medium, on the basis of the reference image. The image inspection device 300 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, at a predetermined timing in a step in which the image formation part 330 forms the image that is inspected by the image inspection part 350.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an image inspection apparatus, an image inspection method, and an image inspection program.

Background Art

[0002] Conventionally, a method of 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 is 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 process 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] In addition, when performing overprinting on the printed surface of a sheet on which an image has already been printed, based on the original image from above, if the overprinted printed matter is inspected using the original image as a reference image, there is a problem that an error occurs even when there is no problem with the quality of the printed matter. Therefore, when inspecting the overprinted printed matter, it is necessary to pre-register, as a reference image, a printed matter in which the user has confirmed that there is no problem with the quality, among the overprinted printed matters.

[0006] The present invention has been made in view of the above circumstances. An object of the present invention is to provide an image inspection apparatus, an image inspection method, and an image inspection program that can improve the productivity of inspecting printed matter by printing that does not require pre-registration of a reference image, and can also appropriately perform inspection of printed matter by printing that requires pre-registration of a reference image.

Means for Solving the Problems

[0007] The above object of the present invention is achieved by the following means.

[0008] (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 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, having, at a predetermined timing in the image forming process by the image forming unit of the image to be inspected by the image inspection unit, 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 apparatus.

[0009] (2) The image inspection apparatus according to (1) above, wherein the predetermined timing includes the acquisition timing of a job based on the image data.

[0010] (3) The image inspection apparatus according to (1) above, wherein the predetermined timing includes the image forming start timing by the image forming unit.

[0011] (4) The image inspection apparatus according to (1) above, wherein the predetermined timing includes the timing during image formation by the image forming unit.

[0012] (5) The image data is image data for forming images of a plurality of pages on a recording medium, The image inspection apparatus according to (4) above, wherein the predetermined timing includes the timing during image formation of at least the first page.

[0013] (6) The image inspection apparatus according to (1) above, wherein the second inspection mode performs generation of the reference image and formation of the image on the recording medium in parallel.

[0014] (7) The image inspection apparatus according to (1) or (6) above, further comprising a control unit that controls the image forming unit, the reference image generation unit, and the image inspection unit, wherein when the second inspection mode is specified, the control unit performs a reference image generation step including generation of a reference image by the reference image generation unit, formation of the image on the recording medium by the image forming unit, and an inspection step including inspection of a read image generated by reading the recording medium on which the image is formed by the image inspection unit, in parallel.

[0015] (8) The image inspection apparatus according to (1) or (2) above, wherein the reference image registered in the first inspection mode is a read image generated by reading a recording medium.

[0016] (9) The image inspection apparatus according to (1) or (2) above, wherein the first inspection mode is selected in the case of inspection of overprinting.

[0017] (10) An image inspection method by an image inspection apparatus, wherein the image inspection apparatus forms an image on a recording medium based on acquired image data, generates a reference image for inspecting the image formed on the recording medium, inspects the image formed on the recording medium based on the reference image, and at a predetermined timing in the image forming step of the image to be inspected, 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.

[0018] (11) An image inspection program for causing a computer to execute the image inspection method according to (10) above.

Advantages of the Invention

[0019] According to the present invention, while improving the productivity of inspecting printed matter by printing that does not require prior registration of a reference image, it is also possible to appropriately perform the inspection of printed matter by printing that requires prior registration of a reference image.

Brief Description of the Drawings

[0020]

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Embodiments for Carrying Out the Invention

[0021] Hereinafter, embodiments of the present invention will be described with reference to the attached drawings. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant descriptions are omitted. Also, the dimensional ratios in the drawings are exaggerated for convenience of explanation and may be different from the actual ratios.

[0022] <Configuration of the Printing System> FIG. 1 is a schematic block diagram of a printing system according to an embodiment of the present invention, and FIG. 2 is a schematic block diagram exemplifying the configuration of the image forming system shown in FIG. 1.

[0023] As shown in FIG. 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 communicably connected to each other through a communication line 400.

[0024] The client terminal 200 can be, for example, a personal computer, a tablet terminal, a smartphone, or the like. A printer driver for converting manuscript data into a print job is installed in the client terminal 200. The printer driver generates a print job in a format that the print controller unit 320 (see FIG. 2) of the image forming system 300 can handle, and transmits the print job to the image forming system 300 through the communication line 400. Further, the client terminal 200 is provided with a display and can display inspection results (good / defective) of printed matter, images of defective printed matter, and the like.

[0025] The print job includes a reference image generation job and an inspection job. The inspection job includes, for example, print data in PDL (Page Description Language) format and job information. The print data includes, for example, data consisting of the first to nth pages. The job information includes, for example, print settings such as the number of pages, the number of copies, the type, size, basis weight of the paper (recording medium), single-sided printing / double-sided printing, inspection setting (on / off), and print mode. The print mode includes, for example, a normal print mode and an overprint mode. By turning on the inspection setting, the user can give an instruction for image inspection to the image forming system 300.

[0026] The communication line 400 can include a LAN (Local Area Network) that connects computers and network devices to each other according to a predetermined standard, or a WAN (Wide Area Network) that connects LANs to each other with a dedicated line. The predetermined standard is, for example, Ethernet (registered trademark), FDDI (Fiber Distributed Data Interface), Wi-Fi (Wireless Fidelity), or the like.

[0027] Note that the number of each of the above components connected to the communication line 400 is not limited to the case illustrated in FIG. 1.

[0028] <Configuration of the image forming system 300> As shown in FIGS. 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.

[0029] <Configuration of the control unit 310> The control unit 310 includes an image control CPU (Central Processing Unit) 311, a DRAM (Dynamic Random Access Memory) control IC 312, a memory 313, an image memory (DRAM) 314, a compression / expansion IC 315, a reading processing unit 316, a writing processing unit 317, a storage unit 318, etc.

[0030] The image control CPU 311 expands various programs stored in the storage unit 318 into the memory 313, and collaborates with the expanded programs to comprehensively control the operation of the entire image forming system 300.

[0031] 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. Also, the generated digital image data is output to the compression / expansion IC 315 by the DRAM control IC 312. The compression / expansion IC 315 performs compression processing on the digital image data and expansion processing on the compressed digital image data based on the control of the DRAM control IC 312. Also, the DRAM control IC 312 performs input / output control of the image memory (DRAM) 314 on the compressed / expanded digital image data.

[0032] The image memory 314 is composed of DRAM and has areas for a compression memory and a page memory inside, and temporarily stores compressed image data, expanded image data, etc.

[0033] The writing processing unit 317 outputs the extended digital image data to the exposure unit 332 of the image forming unit 330.

[0034] <Configuration of the Print Controller Unit 320> The print controller unit 320 analyzes the print job received from the client terminal 200 through the communication line 400, executes processes 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.

[0035] The print controller unit 320 includes a controller control unit 321, a DRAM control IC 322, an image memory (DRAM) 323, a communication control unit 324, a communication I / F 325, etc. The controller control unit 321 comprehensively controls the operations of each part of the print controller unit 320. Also, the controller control unit 321 receives a print job from the client terminal 200 etc. via the communication I / F 326. The communication control unit 324 controls the communication I / F 325.

[0036] The received print job includes print data (mainly in PDL format) that is the source of the original image, and job information describing print settings such as the type of paper to be used. The print controller unit 320 performs a rasterization (RIP) process to convert the print data into page-unit bitmap data based on the print settings. The RIP image after the rasterization process is temporarily stored in the image memory 323. The RIP image in the image memory 323 is temporarily stored in the compressed memory area in the image memory 314 via the compression / expansion 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 expanded by the compression / expansion IC 315 and sent to the image forming unit 330 as an original image (image data) via the writing processing unit 317, and printing is executed.

[0037] At a predetermined generation timing, the control unit 310 outputs a reference image generation instruction to a reference image generation unit 380, which will be described later, so as to generate a reference image based on the document image. The reference image generation unit 380 generates a reference image based on the reference image generation instruction.

[0038] Ideally, it is considered that the read image generated by reading the inspection image formed on the paper matches the document image in terms of content. However, when reading the inspection image formed on the paper by a scanner, errors may occur in the read image with respect to the document image due to various factors such as variations in the paper conveyance path, misalignment of the reading position by the scanner, color reproducibility, and differences in paper types. In addition, errors may occur in the document image depending on the resolution of the scanner reading. Therefore, there is a high possibility of errors if the read image and the document image are simply compared, and it is not practical to inspect the inspection image by simply comparing the read image and the document image. Therefore, in this embodiment, a reference image is generated by performing various processes on the document image with respect to position, resolution, color, etc. so that it can be compared with the read image, and the reference image and the read image are compared. As a result, since the comparison with the read image is appropriately performed, the inspection of printed matter can be performed with high accuracy. The details of the reference image generation process will be described later.

[0039] <Configuration of the image forming unit 330> The image forming unit 330 forms (prints) an image on a sheet of paper by an electrophotographic method including the steps of charging, exposure, development, transfer, and fixing, according to the instructions of the control unit 310. In the present embodiment, the image forming unit 330 forms an inspection image to be inspected by the image inspection unit 350 on a sheet of paper under the image forming conditions set based on the print settings. The image forming unit 330 includes a printer control unit 331, an exposure unit 332, and the like. The printer control unit 331 is connected to the image control CPU 311 by serial communication and receives control by 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 a photoreceptor (not shown). The toner image formed on the photoreceptor is developed through the developing process and transferred onto the sheet of paper supplied from the paper feeding unit 370. Then, the unfixed toner image on the sheet of paper is fixed by being heated and pressurized. The sheet of paper on which the toner image is fixed is conveyed to the image reading unit 340.

[0040] Further, the image forming unit 330 includes a printed sheet discharging device that discharges (purges) a sheet of paper (a defective sheet) on which an inspection image in which an abnormality has been detected by the image inspection unit 350 is formed, separately from a sheet of paper on which a normal inspection image is formed.

[0041] <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 a sheet of paper (printed matter) conveyed through a conveyance path, for example, by a CCD (Charge Coupled Device) image sensor. The scanner control unit 342 controls the scanner to read the inspection image formed on the sheet of paper conveyed from the image forming unit 340 according to a reading instruction from the control unit 310. The scanner control unit 342 outputs the read image obtained by reading the inspection image formed on the sheet of paper to the control unit 310.

[0042] <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 the reference image and the read image, and inspects the inspection image formed on the sheet by comparing the reference image and the read image page by page.

[0043] 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, a RAM, a ROM, and an auxiliary storage device (not shown). 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) in pixel values between the reference image and the read image page by page, and determines the quality of the inspection image according to the magnitude of the difference. The calculation of the difference can be performed page by page, object by object, or region by region. For example, when calculating the difference page by page, if the total value of the differences of the pixels within one page is less than a specified value, a "good" inspection result is output, and if the total value of the differences is greater than or equal to the specified value, a "bad" inspection result is output. Also, when calculating the difference object by object or region by region, it can be configured to output a "good" or "bad" inspection result according to the total value of the differences of the pixel values within the selected object or region.

[0044] When the inspection result of the inspection image is "good", the control unit 310 determines that the printed matter is a good product, and when the inspection result of the inspection image is "bad", the control unit 310 determines that the printed matter is a defective product.

[0045] <Configuration of the operation display unit 360> The operation display unit 360 includes a touch panel display 361, an operation control unit 362, a numeric keypad as a hard key, a start button, a stop button, etc. The touch panel display includes, for example, a touch sensor and an LCD (Liquid Crystal Display) disposed on the back of the touch sensor. The operation control unit 362 receives inputs from the touch sensor and the hard keys, and transmits the input data to the control unit 310. Also, the operation control unit 362 receives output data from the control unit 310 and causes it to be displayed on the LCD. The operation display unit 360 is used for input of various settings (e.g., on / off of inspection settings) and instructions (e.g., an instruction to start printing) by the user. Also, the operation display unit 360 is used for output (display) of the state of the image forming system 300, the inspection results (good / defective) of printed materials, images of defective printed materials, etc.

[0046] <Configuration of the paper feeding unit 370> The paper feeding unit 370 includes at least one large-capacity paper tray, and supplies paper to the image forming unit 330 one sheet at a time.

[0047] <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 realized by a CPU (not shown) different from the image control CPU 311 executing an image inspection program. Thereby, in the second inspection mode described later, it is configured to execute generation of the reference image, formation of the inspection image, and inspection in parallel. Alternatively, when the image control CPU 311 is a multi-core CPU, the reference image generation unit 380 may be assigned to a core different from the processing of forming and inspecting the inspection image, and the generation of the reference image and the formation and inspection of the inspection image may be executed in parallel by different cores.

[0048] Conventionally, the generation of the reference image, and the formation and inspection of the inspection image were configured to be executed by the same CPU. Therefore, since the CPU executes the formation and inspection of the inspection image after the generation of the reference image is completed for each page, the generation of the reference image and the formation and inspection of the inspection image could not be executed in parallel. In the present embodiment, since the generation of the reference image, and the formation and inspection of the inspection image are configured to be executed by separate CPUs, the generation of the reference image and the formation and inspection of the inspection image can be executed in parallel.

[0049] Also, when the manuscript image is a complex image, the computational load for generating the reference image may increase significantly. By having a CPU different from the image control CPU 311 handle the generation of the reference image, the computational load on the image control CPU 311 can be reduced.

[0050] <Configuration of the 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 manuscript image, by using the reference image stored in the storage device 390, it is not necessary to generate the reference image again. Therefore, the time required for generating the reference image can be saved.

[0051] <Outline of the control operations of the control unit 310 and the print controller unit 320> [Generation and registration of reference image] As described above, the reference image generation unit 380 generates a reference image for each page based on the manuscript image. The control unit 310 registers the reference image whose quality has been confirmed by the user as the reference image to be used for inspecting the inspection image. Note that the confirmation of the quality of the reference image can be appropriately omitted according to the user's instruction, and the generated reference image can be registered immediately.

[0052] In this case, the generation of the reference image only needs to be completed before the inspection of the printed matter to be inspected starts. For example, when the control unit 310 generates a reference image based on the original image of the overprinted printed matter, the control unit 310 controls the reference image generation unit 380 to generate a reference image during the period from the acquisition of the reference image generation job to the formation of the image of the printed matter to be inspected on the printed paper.

[0053] When generating a reference image based on the original image, the generation of the reference image is started in response to the acquisition of the reference image generation job. Also, it may be configured to receive a user's instruction through the operation display unit 360 and adjust the start timing of the generation of the reference image.

[0054] Alternatively, instead of generating a reference image by the reference image generation unit 380, an image may be stored in advance in the storage device 390 and configured to be registered as a reference image in response to a user's instruction.

[0055] [Inspection Mode] The image forming system 300 has a plurality of 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 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 be able to execute any of a plurality of inspection modes including the first inspection mode and the second inspection mode. For example, the user can set the printing mode to the overprinting mode or the normal mode through the printing settings of the job information. When the overprinting mode is set, the control unit 310 designates (selects) the first inspection mode, and when the normal mode is set, the control unit 310 designates the second inspection mode.

[0056] The image forming process is a process executed from the acquisition of a print job (inspection job) until an inspection image based on the original image is formed on a sheet by the image forming unit 330. The predetermined timing may include the acquisition timing of the inspection job. Further, the predetermined timing may include the image forming start timing by the image forming unit 330 or the timing during image formation. When the original image includes images of a plurality of pages, the predetermined timing may include the timing during image formation for at least the inspection image of the first page (see, for example, FIGS. 10 and 12).

[0057] In the first inspection mode, the image inspection unit 350 inspects the printed matter to be inspected, for example, using a reference image that has been quality-checked and registered by the user among the reference images generated by the reference image generation unit 380. Alternatively, the control unit 310 registers, as a reference image, an image whose quality has been previously confirmed by the user among the images stored in the storage device 390, and the image inspection unit 350 inspects the printed matter to be inspected using the registered reference image. For example, the control unit 310 registers, as a reference image, a read image whose quality has been confirmed by the user among a plurality of read images generated by reading a printed matter overprinted on a printed sheet. The image inspection unit 350 inspects the overprinted printed matter to be inspected using the registered reference image. This can prevent an error from occurring even when there is no problem with the quality of the printed matter when inspecting the overprinted printed matter by using the original image as the reference image as it is.

[0058] On the other hand, in the second inspection mode, at the above-mentioned predetermined timing, the reference image is not registered. The reference image is registered before the inspection of the inspection image starts. In the second inspection mode, the control unit 310 controls the reference image generation unit 380 and the image forming unit 330 so as 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 the reference image by the reference image generation unit 380 when the second inspection mode is specified as the inspection mode. Further, the inspection process includes the formation of the 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 is formed by the image inspection unit 350. Thereby, the time required for the process from the generation of the reference image to the image inspection can be shortened. As a result, the productivity of the printed matter is improved.

[0059] As described above, in the present embodiment, at the above-mentioned predetermined timing, the first inspection mode or the second inspection mode can be specified according to whether the reference image is registered. As described above, the printing mode includes a normal printing mode and an overprinting mode. In the case of the overprinting mode, the reference image is registered. For example, depending on whether pre-registration of the reference image, that is, printing that requires registration of the reference image before execution of the image forming process, such as overprinting, the control unit 310 executes the first inspection mode or the second inspection mode. For example, when the printing mode is the overprinting mode, the first inspection mode is executed, while when the printing mode is not the overprinting mode, the second inspection mode may be configured to be executed.

[0060] Further, in the present embodiment, when a reference image of a quality desired by the user is registered in advance, the control unit 310 may be configured to execute the first inspection mode. Thereby, the user's desires regarding the quality of the reference image can be surely reflected.

[0061] Next, in each of the first inspection mode and the second inspection mode, an overview of the control operations of the control unit 310 and the print controller unit 320 will be described.

[0062] [First Inspection Mode] The inspection in the first inspection mode consists of two steps: a step of generating a reference image and a step of inspecting an inspection image. Hereinafter, each of these steps will be described in detail.

[0063] (Step of Generating a Reference Image) FIG. 3 is a block diagram for explaining an overview of the control operations of the control unit 310 and the print controller unit 320 in the step of generating a reference image in the first inspection mode.

[0064] First, the control unit 310 receives a document image and job information from the document image acquisition unit (print controller unit 320) ((1)-1 Image Input). The document image is a RIP image obtained by rasterizing print data. The control unit 310 stores the document image input by the document image acquisition unit in the page memory 1.

[0065] Next, the control unit 310 outputs the document 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 a sheet of paper (printed paper) based on the document image. After the paper discharge of the sheet of paper is completed, the image forming unit 330 notifies the control unit 310 of the completion of the paper discharge ((3)-1 Output Completion).

[0066] 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, stores the read image in the page memory 2, and notifies the control unit 310 of the completion of the reading ((5)-1 Image Reading Completion).

[0067] 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 stores the reference image in the page memory 1. After generating the reference image, the reference image generation unit 380 notifies the control unit 310 of the completion of the generation of the reference image ((7)-1 reference image generation completion). Also, the control unit 310 stores the reference image stored in the page memory 1 in the storage device 390 ((8)-1 reference image storage).

[0068] The control unit 310 repeats the above processes (1)-1 to (8)-1 until the generation of the reference image is completed for all pages of the printed matter to be inspected.

[0069] As described above, the reference image generation unit 380 performs various processes on the reference image regarding position, resolution, color, etc. to generate the reference image. For example, the reference image generation unit 380 can extract the position information of the content part from the original image and add or embed the position information into the reference image so that the content parts (contents) of the reference image and the read image can be compared with each other. That is, 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. Note that the alignment information includes contour information and edge information of the image. Also, the reference image generated by the reference image generation unit 380 has area information regarding the inspection area and the inspection exclusion area used when performing image inspection based on the reference image. Furthermore, the reference image generation unit 380 can generate the reference image by adjusting the resolution of the original image so as to match the resolution of the scanner of the image reading unit 340. Also, the reference image generation unit 380 can generate the reference image by converting the color space of the original image so as to match the color space (e.g., RGB) adopted by the scanner of the image reading unit 340.

[0070] (Step of inspecting the inspection image) FIG. 4 is a block diagram for explaining the outline of the control operations of the control unit 310 and the print controller unit 320 in the process of inspecting the inspection image in the first inspection mode.

[0071] 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 print data. The control unit 310 stores the original image input by the original image acquisition unit in the page memory 1.

[0072] 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 a sheet of paper (printed sheet) based on the original image. After the sheet of paper is discharged, the image forming unit 330 notifies the control unit 310 of the completion of the sheet discharge ((3)-2 Output Completion).

[0073] 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, stores the read image in the page memory 2, and notifies the control unit 310 of the completion of the reading ((5)-2 Reading Completion).

[0074] Next, the control unit 310 instructs the storage device 390 to read out the reference image ((6)-2 Reading out the Reference Image), and reads out the reference image from the storage device 390 to the page memory 1.

[0075] 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 the reference image and the read image from the page memory 1 and the page memory 2 respectively, and inspects the inspection image by comparing the reference image with the read image. Then, the image inspection unit 350 notifies the control unit 310 of the inspection result of the inspection image ((8)-2 Image Inspection Result).

[0076] The control unit 310 repeats the processes of (1)-2 to (8)-2 until the inspection is completed for all pages of the printed matter to be inspected.

[0077] The control unit 310 controls to display the inspection result (good product / defective product) of the printed matter on the operation display unit 360 or the display of the client terminal 200 based on the inspection result of the inspection image in response to an instruction from the user.

[0078] [Second Inspection Mode] FIG. 5 is a block diagram for explaining an overview of the control operations of the control unit 310 and the print controller unit 320 in the second inspection mode.

[0079] 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 by the original image acquisition unit in the page memory 1.

[0080] 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 stores the reference image in the page memory 1. As described above, the reference image generation unit 380 performs various processes on the original image with respect to position, resolution, color, etc. to generate a reference image.

[0081] Also, when the control unit 310 receives the original image from the original image acquisition unit, it gives an image formation instruction to the image forming unit 330 and outputs the original image stored in the page memory 1 to the image forming unit 330 ((2)-3 Image Output). In the present embodiment, the image forming unit 330 forms an inspection image on the paper based on the original 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 executed in parallel.

[0082] When the generation of the reference image is completed, the reference image generation unit 380 notifies the control unit 310 of the completion of the reference image generation ((3)-3 Completion of reference image generation). Also, when the image formation on the paper is completed, the image forming unit 330 notifies the control unit 310 of the completion of output ((3)-3 Completion of output). The storage device 390 stores the generated reference image ((4)-3 Storage of reference image).

[0083] Also, as soon as the control unit 310 receives the notification of the completion of output, 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 is formed and outputs the read image of the paper to the control unit 310. The control unit 310 stores the read image in the page memory 2. When the reading of the paper is completed, the image reading unit 340 notifies the completion of image reading ((5)-3 Completion of image reading).

[0084] Upon receiving the notification of the completion of image reading, 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 the reference image and the read image from the page memory 1 and the page memory 2 respectively, and inspects the inspection image by comparing the reference image with the read image. Then, the image inspection unit 350 outputs the inspection result of the inspection image to the control unit 310 ((7)-3 Image inspection result).

[0085] The control unit 310 repeats the processes of (1)-3 to (7)-3 above until the inspection is completed for all pages of the printed matter to be inspected.

[0086] The control unit 310 controls to display the inspection result (good product / defective product) of the printed matter on the operation display unit 360 or the display of the client terminal 200 based on the inspection result of the inspection image in response to an instruction from the user.

[0087] <Image inspection method by the image forming system 300> FIG. 6 is a flowchart illustrating the processing procedure of the image inspection method by the image forming system 300 shown in FIG. 1. The processing shown in FIG. 6 is realized by the image control CPU 311 executing an image inspection program. Hereinafter, the case where the print mode is the overprint mode will be exemplified and described as a case where prior registration of a reference image is required.

[0088] First, when a print job is started, the control unit 310 determines whether the print mode is the overprint mode (step S101). When the print mode is the overprint mode (step S101: YES), the control unit 310 executes the first inspection mode. On the other hand, when the print mode is not the overprint mode (step S101: NO), the control unit 310 executes the second inspection mode.

[0089] Note that in the above, based on the selected print mode, it is determined whether the inspection mode to be executed is the first inspection mode or the second inspection mode. However, the user may be allowed to specify the inspection mode, and it may be determined whether the received inspection mode is the first inspection mode or the second inspection mode.

[0090] [First Inspection Mode] FIG. 7 is a subroutine flowchart illustrating the details of the processing of executing the first inspection mode (step S102) in the flowchart shown in FIG. 6. FIG. 8 is a subroutine flowchart following FIG. 7. The processing shown in FIGS. 7 and 8 is realized by the image control CPU 311 executing an image inspection program. FIG. 9 is a schematic diagram showing the processes of acquiring a document image and generating a reference image in the reference image generation step in chronological order. FIG. 10 is a schematic diagram showing the processes of acquiring a document image, forming an inspection image, and inspecting the inspection image in the image formation step in chronological order.

[0091] As shown in FIG. 7, first, the control unit 310 acquires a document image (step S201). The control unit 310 sequentially receives each page of the document image (RIP image) from the first page to the final nth page one by one from the document image acquisition unit. For example, FIG. 9 illustrates a case where the document image is received sequentially from the first page to the eighth page. In FIGS. 9, 10, and 12, "1P" represents the first page (the same applies to "2P", etc.). Note that 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. For example, the complexity of the content is cited as a factor for the generation time of the reference image to vary from page to page. FIG. 9 shows an example where it takes time to generate the reference image of the second page.

[0092] Next, the control unit 310 saves the document image (step S202). When the print job is started, the control unit 310 saves each page of the document image acquired from the document image acquisition unit in the page memory 1 one by one.

[0093] Next, the control unit 310 prints an image based on the document image (step S203). The control unit 310 controls the image forming unit 330 to form an image on a sheet (printed sheet) based on the document image received from the document image acquisition unit and the job information. For example, the control unit 310 performs "print preparation" and controls the image forming unit 330 to form an inspection image on the sheet for the first page of the document image. The image forming unit 330 forms an image on the sheet for the first page of the document image according to the instruction of the control unit 310. After the image of the first page of the document image is formed on the sheet, the image is similarly formed on the sheet for the second page of the document image. Note that "print preparation" includes initial settings and preparations of each part according to the image forming conditions in the image forming unit 330 (for example, warm-up of the fixing unit), etc.

[0094] Next, the image reading unit 340 reads the image formed on the print sheet (step S204) and transmits it to the control unit 310 as a read image. The control unit 310 saves the read image received from the image reading unit 340 in the page memory 2.

[0095] Next, the reference image generation unit 380 generates a reference image (step S205). The reference image generation unit 380 generates a reference image to be used for inspecting the inspection image according to the instruction of the control unit 310. As shown in FIG. 9, for example, when the first page of the original image is acquired and stored in the 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. Similarly, a reference image is generated for the second page of the original image.

[0096] 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 page and the second page of the original image.

[0097] Next, the control unit 310 determines whether all pages have been acquired (step S207). If the control unit 310 has not acquired all pages of the original image for the printed matter to be inspected (step S207: NO), the process proceeds to the process of step S201.

[0098] On the other hand, if the control unit 310 has acquired all pages of the original image (step S207: YES), the process proceeds to the process of step S208 in FIG. 8.

[0099] As shown in FIG. 8, the control unit 310 acquires the original image (step S208). The original image is an image to be formed on the printed paper for overprinting.

[0100] Next, the control unit 310 stores the original image (step S209). The control unit 310 stores the original image acquired from the original image acquisition unit page by page in the page memory 1.

[0101] 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.

[0102] Next, the image forming unit 330 prints an image based on the document image (step S211). The control unit 310 controls the image forming unit 330 to form an inspection image on a sheet (printed sheet) based on the document image received from the document image acquisition unit and the job information. For example, the control unit 310 performs printing preparation and controls the image forming unit 330 to form an inspection image on the sheet for the document image of the first page. The image forming unit 330 forms an inspection image on the sheet for the first page of the document image according to the instruction of the control unit 310. After the inspection image is formed based on the document image of the first page, the inspection image is similarly formed on the sheet for the document image of the second page.

[0103] Next, the image reading unit 340 reads the inspection image formed on the sheet (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.

[0104] Next, the image inspection unit 350 inspects the inspection image by comparing the reference image stored in the page memory 1 with the read image stored in the page memory 2 (step S213).

[0105] Next, the control unit 310 determines whether all pages of the document image have been acquired for the printed matter to be inspected (step S214). If the control unit 310 has not acquired all pages (step S214: NO), it proceeds to the process of step S208. On the other hand, if the control unit 310 has acquired all pages (step S214: YES), the process ends (returns).

[0106] As described above, in the first inspection mode, a reference image is registered at the above-described predetermined timing. As shown in FIG. 10, the predetermined timing may include the acquisition timing of the inspection job. Further, the predetermined timing may include the image formation start timing of the inspection job by the image forming unit 330 or the timing during the image formation of the inspection job. When the original image includes images of a plurality of pages, the predetermined timing may include the timing during the image formation for at least the inspection image of the first page.

[0107] Note that, in the above example, the case of generating and registering a reference image based on the original image has been mainly described. However, the present invention is not limited to such a case, and based on a user's instruction, for example, an image previously stored in the storage device 390 can be registered as the reference image.

[0108] [Second Inspection Mode] FIG. 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 FIG. 11 is realized by the image control CPU 311 executing an image inspection program. FIG. 12 is a schematic diagram showing each process of acquiring an original image, generating a reference image, forming an inspection image, and inspecting the inspection image in chronological order.

[0109] As shown in FIG. 11, first, the control unit 310 acquires an original image (step S301). The control unit 310 sequentially receives each page of the original image (RIP image) from the first page to the final nth page from the original image acquisition unit. For example, FIG. 12 illustrates the case where the original image is received in order from the first page to the eighth page.

[0110] Next, the control unit 310 stores the original image (step S302). When the printing job is started, the control unit 310 stores each page of the original image acquired from the original image acquisition unit in the page memory 1 one by one.

[0111] Next, the control unit 310 controls the generation of a reference image used for inspecting the inspection image. The reference image generation unit 380 generates a reference image according to the instruction of the control unit 310 (step S303). For example, when the first page of the original image is acquired and stored in the 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. Similarly, a reference image is generated for the second page of the original image.

[0112] 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 page and the second page of the original image. Also, in the present embodiment, as shown in FIG. 11, the control unit 310 controls the image forming unit 330 to form an inspection image on a sheet based on the original image and job information received from the original image acquisition unit in parallel with the processes of steps S303 and S304. For example, the control unit 310 performs printing preparation and controls the image forming unit 330 to form an inspection image on a sheet for the first page of the original image. The image forming unit 330 forms an inspection image on a sheet for the first page of the original image according to the instruction of the control unit 310 (step S305). After the inspection image of the first page of the original image is formed, an inspection image is similarly formed on a sheet for the second page of the original image.

[0113] Next, the inspection image formed on the sheet is read (step S306).

[0114] 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 reading unit 340, the image inspection unit 350 compares the reference image with the read image to inspect the inspection image (step S308).

[0115] The control unit 310 repeats the processes of steps S301 to S308 until the inspection of the inspection images is completed for all pages (from the first page to the final nth page) (step S309).

[0116] On the other hand, when the reference image has not been generated (step S307: NO), the image inspection unit 350 waits until the reference image is generated. For example, if the original image (first page) serving as the basis for the inspection image inspected in step S308 and the reference image of the same original image (first page) have not been generated, it waits until the reference image of this original image (first page) is generated.

[0117] As described above, in the second inspection mode, the reference image is not registered at the above-mentioned predetermined timing. As shown in FIG. 12, the predetermined timing may include the acquisition timing of the print job. Further, the predetermined timing may include the image formation start timing by the image forming unit 330 or the timing during the image formation of the print job. In the second inspection mode, there may be a case where the reference image is not registered at the above-mentioned predetermined timing.

[0118] As shown in FIG. 11, the generation of the reference image by the reference image generation unit 380 and the formation and inspection of the inspection image by the image forming unit 330 are performed in parallel. Thereby, the image forming system 300 can further shorten the time required for the processes from the generation of the reference image to the image inspection as compared with the prior art.

[0119] [Parallel generation of the reference image and formation of the inspection image on the paper] For example, in the example shown in FIG. 12, the generation of the reference images for the first page (1P) and the second page (2P) and the print preparation are executed in parallel, and the generation of the reference image for the third page (3P) and the formation of the inspection image for the first page (1P) (the first half) are executed in parallel. Then, thereafter, the generation of the reference image for the fourth page (4P) and the formation of the inspection image for the first page (1P) (the second half) are executed in parallel. Note that in the same figure, the generation of the reference image for the third page (3P) and the formation of the inspection image for the first page (1P) are shown as starting simultaneously, but this is not limiting. The formation of the inspection image for the first page (1P) can be started at an appropriate timing after the print preparation is completed, and the generation of the reference image for the third page (3P) can be started at an appropriate timing after the generation of the reference image for the second page (2P). The same applies to the subsequent pages regarding the start timing of the generation of the reference image and the generation of the inspection image.

[0120] [Parallel execution of reference image generation, inspection image formation on paper, and inspection of inspection images] Also, thereafter, the generation of the reference image for the fifth page (5P), the formation of the inspection image for the second page (2P), and the inspection of the inspection image for the first page are executed in parallel.

[0121] Thus, in the present embodiment, based on the reception of the original image (starting from the reception of the original image), while generating the reference image, when the print preparation is complete, the inspection image is formed on the paper and the inspection of the inspection image is performed. In the present embodiment, since the generation of the reference image and the formation and inspection of the inspection image are executed in parallel, the time required for the process from the generation of the reference image to the image inspection can be shortened. As a result, the productivity of the printed matter is improved.

[0122] According to the image inspection apparatus of the present embodiment described above, the following effects are obtained.

[0123] While improving the productivity of the inspection of printed matter by printing that does not require pre-registration of the reference image, the inspection of printed matter by printing that requires pre-registration of the reference image can also be appropriately performed.

[0124] As described above, the image inspection apparatus, the image inspection method, and the image inspection program have been described in the embodiments. However, it goes without saying that those skilled in the art can appropriately add, modify, and omit within the scope of the technical idea of the present invention.

[0125] For example, in the above-described embodiment, the case of generating a document image based on a print job has been described, but the present invention is not limited to such a case. The image forming unit 330 may have an image reading device 333 (see FIG. 1) that reads a document prepared by a user, and may be configured to generate a document image based on the image generated by reading the document by the image reading device 333. The image reading device 333 reads, for example, a document conveyed to a predetermined reading position by an automatic document feeder by a scanner and generates image data.

[0126] Also, the image inspection program may be provided by a computer-readable recording medium such as a USB memory, a flexible disk, a CD-ROM, etc., or 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 and stored in a memory, a storage, etc. Further, this inspection program may be provided, for example, as a single application software, or may be incorporated into the software of each device as a function of a server.

[0127] Also, in the embodiment, part or all of the processing executed by the inspection program can be replaced by hardware such as a circuit and executed.

Explanation of Reference Numerals

[0128] 100 Printing system, 200 Client terminal, 300 Image forming system, 310 Control unit, 311 Image control CPU, 312 DRAM control IC, 313 Memory, 314 Image memory (DRAM), 315 Compression / expansion IC, 316 Reading processing unit, 317 Writing processing unit, 318 Storage unit, 320 Print controller unit, 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 unit, 333 Image reading device, 340 Image reading unit, 341 Scanner, 342 Scanner control unit, 350 Image inspection unit, 351 Image inspection control unit, 360 Operation display unit, 361 LCD / touch sensor, 362 Operation control unit, 370 Paper feeding unit, 380 Reference image generation unit, 390 Storage device, 400 Communication line.

Claims

1. An image forming unit that forms an image on a recording medium based on the acquired image data; A reference image generation unit that generates a reference image for inspecting the image formed on the recording medium; An image inspection unit that inspects the image formed on the recording medium based on the reference image, and has: In the image inspection apparatus, at a predetermined timing in the image forming step by the image forming unit of the image to be inspected by the image inspection unit, there are a first inspection mode in which the reference image is registered and a second inspection mode in which the reference image is not registered.

2. The image inspection apparatus according to claim 1, wherein the predetermined timing includes an acquisition timing of a job based on the image data.

3. The image inspection apparatus according to claim 1, wherein the predetermined timing includes an image forming start timing by the image forming unit.

4. The image inspection apparatus according to claim 1, wherein the predetermined timing includes a timing during image formation by the image forming unit.

5. The image data is image data for forming images of a plurality of pages on a recording medium, The image inspection apparatus according to claim 4, wherein the predetermined timing includes a timing during image formation of at least the first page.

6. The image inspection apparatus according to claim 1, wherein in the second inspection mode, generation of the reference image and formation of an image on the recording medium are performed in parallel.

7. Further includes a control unit that controls the image forming unit, the reference image generation unit, and the image inspection unit, The control unit is, When the second inspection mode is specified, a reference image generation step including generation of a reference image by the reference image generation unit, formation of the image on a recording medium by the image forming unit, and inspection of the read image generated by reading the recording medium on which the image is formed by the image inspection unit are executed in parallel. The image inspection apparatus according to claim 1 or 6.

8. The reference image registered in the first inspection mode is a read image generated by reading a recording medium. The image inspection apparatus according to claim 1 or 2.

9. In the case of inspection for overprinting, the first inspection mode is selected. The image inspection apparatus according to claim 1 or 2.

10. An image inspection method by an image inspection apparatus, The image inspection apparatus, Forms an image on a recording medium based on the acquired image data, Generates a reference image for inspecting the image formed on the recording medium, Inspects the image formed on the recording medium based on the reference image, An image inspection method 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 at a predetermined timing in the image formation step of the image to be inspected.

11. An image inspection program for causing a computer to execute the image inspection method according to claim 10.

Images