Image inspection device, image inspection method, and image inspection program

Abstract

To shorten time required for processing from generation of a reference image to image inspection.SOLUTION: An image inspection device 100 includes: a reference image generation unit 311 that generates a reference image used for inspection of an image formed on a recording medium; an image inspection unit 312 that inspects the image formed on the recording medium based on the reference image: and a reception unit 115 that receives designation of generation timing of the reference image.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, the quality of printed matter has been inspected by comparing a pre-registered reference image with an inspection image obtained by reading the printed matter to be inspected. For example, in Patent Document 1, as a reference image, in the case of the proof mode for confirming the finished product, image data derived from the original image used for printing is used, and in subsequent mass printing, in the proof mode, the read image data obtained when reading a printed matter confirmed by the user to have no abnormality visually is used.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technique of Patent Document 1, the user's processing for generating the reference image used for mass printing is complicated, and it is necessary to prepare the reference image in advance and then execute the mass printing.

[0005] The present invention has been made in view of the above circumstances, and an object thereof is to provide an image inspection apparatus, an image inspection method, and an image inspection program capable of further shortening the time required for processing from the generation of a reference image to image inspection as compared with the conventional technique.

Means for Solving the Problems

[0006] The above object of the present invention is achieved by the following means.

[0007] (1) A reference image generation unit that generates a reference image used for inspecting an image formed on a recording medium, An image inspection unit that inspects the image formed on the recording medium based on the aforementioned reference image, A reception unit that accepts the specification of the timing for generating the reference image, An image inspection device having the following features.

[0008] (2) The image inspection apparatus according to (1) above, further comprising a control unit that controls the generation of a reference image by the reference image generation unit according to the generation timing received by the reception unit.

[0009] (3) The system further comprises an image forming unit that forms the image on the recording medium based on the original image, The image inspection apparatus according to (1) above, wherein the generation timing includes a first timing which is before image formation by the image forming unit and a second timing which is different from the first timing.

[0010] (4) The image inspection apparatus according to (3) above, wherein the second timing includes the timing during image formation by the image forming unit.

[0011] (5) A control unit that controls the transmission of the original image to the reference image generation unit and the image forming unit based on the acceptance of the second timing specification. The image inspection apparatus according to (3) or (4) above, further comprising the above.

[0012] (6) The image inspection apparatus according to (5) above, wherein the control unit causes the reference image generation unit to generate the reference image and the image formation unit to form the image on the recording medium in parallel.

[0013] (7) The control unit controls the generation of a reference image by the reference image generation unit according to the generation timing received by the reception unit, When the control unit receives the second timing specification, When the aforementioned image inspection unit performs an inspection on a sheet of paper for which an image has been formed based on the document image of page x out of pages 1 to n, The image inspection apparatus according to (3) or (4) above, which determines whether the generation of the reference image for page x by the reference image generation unit has been completed before inspecting page x.

[0014] (8) The control unit controls the generation of a reference image by the reference image generation unit according to the generation timing received by the reception unit, When the control unit receives the second timing specification, When the aforementioned image inspection unit performs an inspection on a sheet of paper for which an image has been formed based on the document image of page x out of pages 1 to n, The image inspection apparatus according to (3) or (4) above, wherein the control unit determines, before inspecting page x, whether the reference image for page x has already been generated by the reference image generation unit and whether the storage of the reference image in the storage unit has been completed.

[0015] (9) The control unit controls the generation of a reference image by the reference image generation unit according to the generation timing received by the reception unit, When the control unit receives the first timing specification, The image inspection apparatus according to (3) or (4) above, which determines whether a registered reference image to be used for inspection by the image inspection unit has been specified before the image forming unit forms an image.

[0016] (10) A reference image generation step that generates a reference image used for inspecting an image formed on a recording medium, An image inspection step of inspecting an image formed on the recording medium based on the aforementioned reference image, A reception step that accepts the specification of the timing for generating the reference image in the aforementioned reference image generation step, Image inspection methods, including those mentioned above.

[0017] A reference image generation step for generating a reference image used for inspecting an image formed on a recording medium, An image inspection step for inspecting the image formed on the recording medium based on the reference image, A reception step for receiving a specification of the generation timing of the reference image in the reference image generation step, An image inspection program for causing a computer to execute a process including the above.

Effect of the Invention

[0018] The image inspection apparatus according to the present invention includes a reference image generation unit that generates a reference image used for inspecting an image formed on a recording medium, an image inspection unit that inspects the image formed on the recording medium based on the reference image, and a reception unit that receives a specification of the generation timing of the reference image. By doing so, the time required for the process from the generation of the reference image to the image inspection can be shortened.

Brief Description of the Drawings

[0019] [Figure 1] It is a diagram showing a schematic configuration of a printing system including an image inspection apparatus according to a first embodiment. [Figure 2] It is a block diagram showing a hardware configuration of the image inspection apparatus. [Figure 3] It is a schematic diagram for explaining the process of image inspection. [Figure 4] It is a schematic diagram showing the flow of each data. [Figure 5] It is a schematic diagram showing, in chronological order, each process of acquiring a document image, generating a reference image, forming an inspection image, and inspecting the inspection image when a first timing is specified. [Figure 6A] It is an example of an operation screen for explaining the specification of a second timing. [Figure 6B] It is an example of an operation screen displayed following FIG. 6A. [Figure 6C] It is an example of an operation screen for explaining the specification of a first timing. [Figure 6D]This is an example of the operation screen that appears following Figure 6C. [Figure 6E] This is an example of the operation screen that appears following Figure 6D. [Figure 6F] This is an example of an operation screen used to explain the specification of the first timing. [Figure 6G] This is an example of the operation screen that appears following Figure 6F. [Figure 7] This is a flowchart showing the processing steps for the image inspection method. [Figure 8A] This flowchart shows the processing procedure in the first inspection mode, which follows Figure 7. [Figure 8B] This is a subroutine flowchart showing the process for determining the completion of the reference image. [Figure 9] This flowchart shows the processing procedure in the second inspection mode, which follows Figure 7. [Figure 10] This is a subroutine flowchart illustrating the process of generating a reference image. [Figure 11] This is a subroutine flowchart illustrating the image inspection process. [Modes for carrying out the invention]

[0020] Embodiments of the present invention will be described below with reference to the attached drawings. However, the scope of the present invention is not limited to the disclosed embodiments. In the description of the drawings, the same elements are denoted by the same reference numerals, and redundant descriptions are omitted. The advantages and features provided by one or more embodiments of the present invention will be fully understood from the detailed description below and the attached drawings. Furthermore, the attached drawings are provided for illustrative purposes only and are not intended to define the scope of the present invention.

[0021] Figure 1 is a diagram showing the schematic configuration of an image inspection device 100 and a printing system 1000 including it according to the first embodiment. Figure 2 is a block diagram showing the hardware configuration of the image inspection device 100. As shown in Figure 1, the printing system 1000 includes a terminal device 80 and one or more image inspection devices 100, which are connected by a network 90.

[0022] The terminal device 80 may be, for example, a personal computer, a tablet, or a smartphone. The terminal device 80 has a printer driver installed for converting document data into a print job. The terminal device 80 is used by a user, such as an operator who operates the image inspection device 100. The printer driver, in response to user instructions, generates a print job in a format compatible with the print controller 13 of the image inspection device 100 (see Figure 2 below) and sends the print job to the image inspection device 100 via the network 90. ​​The terminal device 80 also has a display that can show the inspection results of the printed materials (quality results) (good / defective items), images of defective printed materials, etc.

[0023] A print job includes, for example, print data in PDL (Page Description Language) format (hereinafter also referred to as original image data or original image) and job setting information (hereinafter referred to as job settings). The original image includes, for example, an original image consisting of pages 1 to n. The job settings include, for example, the number of pages, the number of copies, the type of paper (recording medium), size, basis weight, single-sided printing / double-sided printing, and other print settings. The job settings also include inspection conditions. The inspection conditions include whether or not to perform image inspection (inspection setting on / off), and if image inspection is "enabled", the types of the first and second inspection modes are also included. The inspection conditions may also include inspection area specification information (described later). Furthermore, in the second inspection mode, path information (file directory information) specifying the file of the registered reference image to be used is included. The user can instruct the print system 1000 to perform image inspection by enabling inspection (turning on the inspection setting). The inspection conditions can be set using the operation screen displayed by the printer driver (for example, Figure 6A described later).

[0024] (Image inspection device 100) The image inspection apparatus 100 is also called an image forming system. The image inspection apparatus 100 includes an image forming apparatus 10, a paper feeder 20, an inspection unit 30, a purging apparatus 40, and a post-processing apparatus 50, which are mechanically and electrically connected to each other.

[0025] (Overview of inspection unit 30) The details of the inspection unit 30 will be described later, but the inspection unit 30 has a reference image generation unit 311 that generates a reference image used for inspecting the image formed on the recording medium (paper). The reference image generation unit 311 generates a reference image based on the original image. The inspection unit 30 also has an image inspection unit 312 that inspects the image formed on the paper based on the reference image. The image forming apparatus 10 (image forming unit 16) forms an image on the paper based on the original image. The image inspection unit 312 inspects the image on the paper by reading the image on the paper based on the original image and comparing the inspection image obtained with a reference image generated based on the same original image.

[0026] (Image forming apparatus 10) The image forming apparatus 10 performs image formation on paper fed and transported from the upstream paper feeder 20. The image forming apparatus 10 also performs image formation on paper fed from its own paper feeder.

[0027] As shown in Figure 2, the image forming apparatus 10 comprises a main unit control unit 11, a storage unit 12, a print controller 13, a paper feeding unit 14, a transport unit 15, an image forming unit 16, an operation panel 17, and a communication unit 19. These components are interconnected via signal lines such as buses for exchanging signals. Note that in Figure 2, some connection lines between components of the image forming apparatus 10, such as the storage unit 12 and the print controller 13, are omitted. Similarly, some connection lines between components of the inspection unit 30 are omitted.

[0028] (Main unit control 11) The main control unit 11 is composed of a CPU, ROM, RAM, etc., and executes various processes by running programs stored in the ROM and the storage unit 12 (described later), and controls each part of the device and performs various calculations according to the program. The main control unit 11 functions as a printer control unit 111, an inspection unit control unit 112, an other device control unit 113, a timing specification reception unit 115, a data transmission unit 116, and an inspection area reception unit 117. Details of each sub-function will be described later. The main control unit 11 works in cooperation with the control unit 31 of the inspection unit 30, etc., to control the entire image inspection device 100.

[0029] (Storage unit 12) The storage unit 12 consists of an auxiliary storage unit such as a hard disk that stores various programs and data in advance. The storage unit 12 also functions as a page memory (the storage unit 32 described later does the same).

[0030] (Print controller 13) The print controller 13 analyzes the print job received from the terminal device 80 via the network 90, 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 31. The print controller 13 functions as an original image acquisition unit.

[0031] The print controller 13 receives print jobs from terminal devices 80, etc., via the communication unit 19. The received print job includes print data (mainly in PDL format) that forms the basis of the original image (also called original image data), and job information that describes print settings such as the type of paper to be used. Based on the print settings, the print controller 13 performs rasterization (RIP) processing to convert the print data into page-level bitmap data. The RIP image after rasterization is temporarily stored in the image memory inside the print controller 13. The RIP image in the image memory is temporarily stored in the compressed memory area of ​​the page memory of the storage unit 12. During normal printing, the RIP image stored in the compressed memory area is decompressed by the compression / decompression IC and sent to the image forming unit 16 as the original image via the writing processing unit, and printing is performed.

[0032] (Paper feeding section 14, transport section 15) The paper feeding unit 14 is equipped with multiple paper trays. The transport unit 15 is equipped with a transport path. This transport path includes multiple pairs of transport rollers provided along the transport path, and a drive motor (not shown) that drives these pairs of transport rollers. The paper feeding unit 14 is equipped with a feed roller that feeds out the top sheet of paper from among the multiple sheets of paper stacked and placed in the paper tray, and feeds the paper in the paper tray one sheet at a time to the transport path downstream.

[0033] (Image forming unit 16) The image forming unit 16 forms images, for example, by an electrophotographic method. The image forming unit 16 includes writing units (laser exposure units) corresponding to each of the basic colors Y (yellow), M (magenta), C (cyan), and K (black), a photosensitive drum, and a developer unit that contains a two-component developer consisting of toner and carrier for each color. The image forming unit 16 also further includes an intermediate transfer belt, a secondary transfer unit, and a fixing unit. The toner images formed on the photosensitive drum by the developer units for each color are superimposed on the intermediate transfer belt and transferred to the transported paper in the secondary transfer unit. The toner images on the paper are fixed to the paper by heating and pressurizing in the downstream fixing unit.

[0034] (Control panel 17) The control panel 17 includes a touchscreen, a numeric keypad, a start button, a stop button, and the like. The control panel 17 displays the status of the image forming apparatus 10 or the image inspection apparatus 100 and is used for inputting various settings and instructions from the user. It also displays the inspection results from the inspection unit 30 and accepts input for setting inspection conditions and execution instructions.

[0035] (Communications Section 19) The communication unit 19 is an interface for communicating with various devices on the network, such as PCs, or with other devices 20, 30, etc.

[0036] (Sub-functions 111-117) (Printer control unit 111) When a print job is input, the printer control unit 111 executes the print job based on the print job setting information (hereinafter referred to as "job settings") of the input print job. Print jobs are input by instructions sent from the operation panel 17 or from a terminal device 80 such as a network-connected PC operated by the user. The job settings include print settings and inspection conditions. Print settings include double-sided / single-sided printing, paper type, post-processing conditions, etc. Details of the inspection conditions will be described later, but they are set, for example, by the operation screen shown in Figure 6A below.

[0037] The printer control unit 111 controls the paper feeding and transport by controlling the paper feeding unit 14 and the transport unit 15. The printer control unit 111 also controls the image forming unit 16 to form an image on the paper according to the set image forming conditions.

[0038] The inspection unit control unit 112 controls the inspection unit 30 in response to an execution instruction request (inspection instruction) from the printer control unit 111.

[0039] The other device control unit 113 controls the paper feed device 20, the purge device 40, and the post-processing device 50. Specifically, the other device control unit 113 communicates with the paper feed device 20 to send and receive information such as the paper tray to be used and the paper transport timing. The other device control unit 113 also sends to the purge device 40 the paper transport timing, the main and sub transport paths for the paper to be transported, and post-processing setting information to the post-processing device 50.

[0040] (Timing specification reception unit 115) The timing specification reception unit 115 receives a specification for the generation timing of the reference image. The main control unit 11 controls the generation of the reference image by the reference image generation unit 311 or the generation timing based on the received generation timing. The generation timing includes a first timing and a second timing that is different from the first timing. The first timing is before image formation by the image forming apparatus 10 (or image forming unit 16). The second timing is, for example, during image formation. More specifically, when generating an image and a reference image based on a multi-page original image, the generation of the reference image is started while the image is being formed. "During image formation" refers to the period from when the paper feeding unit 14 starts feeding the first page of the multi-page original image for image formation, until the image formation by the image forming unit 16 on the last page is completed and the paper leaves the image forming unit 16. An example of the first timing will be described later (Figure 5).

[0041] (First inspection mode, second inspection mode) In the embodiments described below, image inspection where the reference image generation timing is the first timing corresponds to the second inspection mode. Similarly, image inspection where the reference image generation timing is the second timing corresponds to the first inspection mode. Examples of accepting both the first and second inspection modes will be described later (Figure 4A, etc.).

[0042] In the first inspection mode, it can be said that the instruction to perform the inspection can be accepted before the generation of the reference image is completed. In the first inspection mode, in parallel with the image formation process of the image to be inspected on the paper by the image forming unit 16 based on the original image, the reference image generation process by the reference image generation unit 311 is performed based on the same original image.

[0043] In the second inspection mode, it can be said that the system can accept an instruction to perform an inspection after the reference image generation process is completed. In the second inspection mode, the reference image generation process is performed by the reference image generation unit 311 based on the original image, and then the inspection is performed by accepting an instruction to perform an inspection using this reference image. Alternatively, in the second inspection mode, an inspection is performed using an already registered reference image. The latter includes both cases where a new reference image is generated and registered for inspection, and cases where a registered reference image is reused.

[0044] (Data transmission unit 116) The data transmission unit 116 transmits the original document image to the image forming unit 16 and the inspection unit 30 (especially the reference image generation unit 311). In particular, the data transmission unit 116 transmits the original document image to the image forming unit 16 and the inspection unit 30 (especially the reference image generation unit 311) in response to the acceptance of the inspection execution for the first inspection mode. For example, in response to the acceptance of the inspection execution for the first inspection mode, the data transmission unit 116 immediately transmits the original document image to both the image forming unit 16 and the reference image generation unit 311 simultaneously. The data transmission unit 116 also transmits the original document image to the image forming unit 16 in response to the acceptance of the inspection execution for the first inspection mode by the second reception unit.

[0045] (Inspection area reception section 117) The inspection area reception unit 117 receives (a) the designation of areas to be excluded from inspection, and (b) the designation of inspection areas (hereinafter, these are collectively referred to as "inspection area designation information"). The inspection area reception unit 117 also transmits the received inspection area designation information to the reference image generation unit 311. The inspection area designation information is described by the target area range (XY coordinate position along the main scanning direction (X direction) and sub-scanning direction (Y direction)) and its contents. The area range is, for example, a rectangular area. (a) Areas designated as areas to be excluded from inspection are not subject to inspection. (b) Areas designated as inspection areas are subject to inspection. In areas designated as inspection areas, it is possible to perform inspections different from the usual. For example, if the original image contains a photograph of a face, the color inspection level will be set more strictly in areas that include skin tones on the face. In addition, barcodes can be specified when designating inspection areas. The original image may contain barcodes (1D or 2D). In this case, in the inspection area designated for the barcode, the image within the inspection area is decoded to verify whether the barcode is printed correctly.

[0046] (Paper feeder 20) The paper feeder 20 shown in Figures 1 and 2 includes a paper feeding section and a transport section similar to those of the image forming apparatus 10. In addition to the transport section and paper feeding section, the paper feeder 20 also includes a control section, a storage section, and a communication section (none of which are shown), which are interconnected via signal lines such as buses for exchanging signals.

[0047] (Inspection unit 30) Next, the inspection unit 30 will be described. As shown in Figure 2, the inspection unit 30 includes a control unit 31, a storage unit 32, an image reading unit 33, a transport unit 34, a communication unit 39, etc. The control unit 31, storage unit 32, transport unit 34, and communication unit 39 each have the same hardware configuration as the main control unit 11, storage unit 12, transport unit 15, and communication unit 19 of the image forming apparatus 10 described above, so their explanation will be omitted.

[0048] The image reading unit 33 reads the paper (printed material) being transported along the transport path, for example, using a CCD (Charge Coupled Device) image sensor. The control unit 31 controls the scanner to read the image (inspection image) formed on the paper transported from the image forming apparatus 10, according to the reading instructions from the inspection unit control unit 112. The control unit 31 also performs various processes such as analog processing, A / D conversion processing, and shading processing on the analog image signal output from the image reading unit 33 to generate digital image (read image) data.

[0049] (Control Unit 31) The control unit 31 functions as a reference image generation unit 311 and an image inspection unit 312.

[0050] The reference image generation unit 311 generates a reference image by performing the following various processes based on the original image acquired by the image forming apparatus 10 (particularly the print controller 13).

[0051] The reference image generation unit 311 and the image inspection unit 312 may each be configured with independent CPUs so that their respective reference image generation and image inspection processes can be performed in parallel. That is, the control unit 31 is composed of multiple CPUs. Alternatively, a multi-core CPU may be used as the CPU for the control unit 31. In the case of a multi-core CPU, the reference image generation unit 311 can be assigned to a different core from the image inspection unit 312's inspection image formation and inspection processes, allowing the generation of reference images and the formation and inspection of inspection images to be performed in parallel by separate cores.

[0052] (Reference image generation unit 311) The reference image generation unit 311 generates a reference image by performing various processes on the original image regarding its position, resolution, color, etc. For example, the reference image generation unit 311 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 scanned image (inspection image) can be compared. In other words, the reference image generated by the reference image generation unit 311 has alignment information (also called alignment features) for aligning the reference image and the inspection image when performing image inspection based on the reference image. The alignment information includes image contour information and edge information. Furthermore, the reference image generated by the reference image generation unit 311 has area information regarding the inspection area and the area to be excluded from inspection, based on the inspection area specification information received by the inspection area reception unit 117 mentioned above. In addition, the reference image generation unit 311 can generate a reference image by adjusting the resolution of the original image to match the resolution of the image reading unit 33 (scanner). Furthermore, the reference image generation unit 311 can generate a reference image by converting the color space of the original image data to match the color space (for example, RGB) adopted by the image reading unit 33.

[0053] The reference image generation unit 311 does not use the original image as is for the following reasons. Ideally, the scanned image (inspection image) generated by reading the image formed on the paper is expected to match the original image in terms of content. However, when scanning the inspection image formed on the paper, errors may occur in the inspection 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 in the inspection image depending on the resolution of the scanner. Therefore, simply comparing the inspection image and the original image is likely to result in errors, and it is not practical to inspect the inspection image by simply comparing it with the original image. In this embodiment, the reference image generation unit 311 is configured to generate a reference image by applying various processing to the original image regarding position, resolution, color, etc., so that it can be compared with the inspection image, and then compare the reference image with the inspection image. This ensures that the comparison with the inspection image is performed appropriately, allowing for accurate inspection of printed materials.

[0054] (Image Inspection Department 312) The image inspection unit 312 performs image inspection based on a reference image. More specifically, the image inspection unit 312 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.

[0055] Figure 3 is a schematic diagram illustrating the image inspection process. The image inspection unit 312 calculates, for example, the difference (error) in pixel values ​​between the reference image and the inspection 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, a "good" inspection result is output, and if the total difference is equal to or greater than the specified value, a "bad" inspection result is output. In addition, when the difference is calculated for each object or region, the system can be configured to output a "good" or "bad" inspection result according to the total difference of pixel values ​​within the selected object or region.

[0056] The control unit 31 determines that the printed material is good if the inspection result of the inspection image is "good," and determines that the printed material is defective if the inspection result of the inspection image is "poor." The determination result is sent to the main control unit 11.

[0057] (Purge device 40) The purging device 40 is provided with a branching section in the transport path, and is equipped with a main transport path leading to the post-processing device 50 and a sub-transport path leading to the purge tray (located on top of the purging device 40 in Figure 1). Paper that has been determined to be of poor quality by the inspection unit 30 is discharged to the purge tray, for example.

[0058] (Post-treatment device 50) The post-processing device 50 performs post-processing on or discharges paper sent from the upstream image forming apparatus 10, according to the settings of the print job. The post-processing device 50 comprises a paper output tray, a post-processing unit, and a transport path. The post-processing device 50 also comprises a control unit, a storage unit, a transport unit, and a communication unit (none of which are shown), which are interconnected via signal lines such as buses for exchanging signals. The post-processing unit performs at least one post-processing operation on the image-formed paper, including stapling, punching, cutting, folding, and binding.

[0059] (Data flow in the image inspection device 100) Figure 4 is a schematic diagram showing the data flow in the image formation and image inspection processes of the image inspection apparatus 100 shown in Figure 2.

[0060] The main control unit 11 acquires job settings (not shown) and the original image from the print controller 13. The original image is a RIP image obtained by rasterizing the print data. The original image is stored in page memory. The job settings include information such as inspection conditions and print settings. The inspection conditions include whether or not image inspection is performed, and if image inspection is performed, the type of first and second inspection mode is also included. Furthermore, in the second inspection mode, path information (file directory information) specifying the file of the registered reference image to be used is included. In the example in Figure 4, the first inspection mode is mainly selected as the job setting. Also, in the example in Figure 4, the original image is described as consisting of n print data from pages 1 to n.

[0061] In the first inspection mode, the main control unit 11 (data transmission unit 116) simultaneously transmits the original document image stored in the page memory to both the image forming unit 16 and the reference image generation unit 311.

[0062] The reference image generation unit 311 generates reference images 1 to n for pages 1 to n in order from the received original document images (pages 1 to n) and stores them in the storage unit 32.

[0063] As shown in Figure 4, x is a value that starts at 1 and increments up to page n. The image forming unit 16 forms images on the paper sequentially from page 1 to page n. x is the current page value.

[0064] The image reading unit 33 reads the transported paper (x pages) and generates a read image. The read image obtained is sent to the image inspection unit 312 via the page memory as the inspection image for page x. In addition, the reference image x for the corresponding page x is sent from the storage unit 32 via the page memory to the image inspection unit 312.

[0065] The image inspection unit 312 inspects the inspection image by comparing it with the acquired reference image. The control unit 31 (image inspection unit 312) then outputs the inspection result of the inspection image to the main control unit 11. In the example shown in Figure 3, the reference image generated by the reference image generation unit 311 is shown to be stored in the storage unit 32, but it may also be stored in the storage unit 12 of the image forming apparatus 10. Also, in Figures 2, 4, etc., the main control unit 11 and the control unit 31 are described as separate units, but they may be configured as a single unit. That is, the control unit 31 may be integrated into the main control unit 11.

[0066] When the timing specification reception unit 115 accepts the request to execute the inspection in the first inspection mode, the generation of the reference image by the reference image generation unit 311 and the formation of the image (inspection image) by the image formation unit 16 are executed in parallel. Figure 5 is a schematic diagram showing the time-series processing of acquiring the original image, generating the reference image, forming the inspection image, and inspecting the inspection image when a second timing is specified. Figure 5 shows the following processes from top to bottom. (Process 1) The main unit control unit 11 acquires the original image. (Process 2) Generation of a reference image by the reference image generation unit 311. (Process 3) Formation of an image of the object to be inspected by the image forming apparatus 10 (image forming unit 16). (Process 4) The image inspection unit 312 performs inspection using the inspection image and the reference image. Furthermore, Figure 5 shows the printing and inspection processes for a total of 8 pages of original images, with n=8. Note that for processes 3 and 4, the processing for pages 3 and 4 onwards is omitted. In Figure 5, the image forming process includes print preparation. Print preparation here includes paper feeding by the paper feeder 20 or paper feed unit 14 for the first page, and data processing such as rasterization by the image forming apparatus 10.

[0067] As shown in Figure 5, the generation of reference images by the reference image generation unit 311 and the formation of inspection images (image formation) by the image formation unit 16 are performed in parallel. Specifically, the generation process of reference images for pages 1 to 8 and the image formation by the image formation unit 16 are performed in parallel.

[0068] (Image examination method) The image inspection method according to this embodiment will be described below with reference to Figures 6A to 11.

[0069] First, the setting of inspection conditions for image inspection in this embodiment will be described. Figures 6A to 6G show the operation screens (operation screens s1 to s7) for setting the inspection conditions for image inspection and issuing execution instructions. Print settings other than the inspection conditions for print job job1, and the specification of the original image are performed using other operation screens (not shown). Operation screens s1 to s7 are displayed on the terminal device 80 or the operation panel 17 on which the printer driver is installed. On operation screens s1, s3, etc., the user can select either radio button b1 or b2. If the user selects b2, they can further select either b21 or b22.

[0070] (Second timing) Referring to Figures 6A and 6B, the second timing specification will be explained. In the operation screen s1 of Figure 6A, buttons b1 (and b3) correspond to the first reception unit. On the operation screen s1, the user selects button b1 and presses the job start button b3. As a result, the timing specification reception unit 115 of the image inspection device 100 receives an execution instruction from the image inspection unit 312 before the reference image generation by the reference image generation unit 311 is completed (first inspection mode). Upon receiving the execution instruction, the image inspection device 100 immediately performs image formation and inspection of the resulting image. The operation screen s2 shown in Figure 6B is displayed following the operation screen s1 of Figure 6A. When the user presses the job start button b3, the timing specification reception unit 115 receives an execution instruction for inspection in the first inspection mode. Accordingly, the operation screen s2 indicating that the first inspection mode has been received is displayed.

[0071] (First timing) Referring to Figures 6C to 6E, the first timing specification (part 1) will be explained. Buttons b2 (and b21, and b5 (operation screen s4)) on the operation screen s3 in Figure 6C correspond to the first timing specification. The user selects button b2, then button b21, and presses the registration start button b4. As a result, the reference image generation unit 311 of the image inspection device 100 generates a new reference image based on the original image and registers the generated reference image in the storage unit 32, etc. After registration, the operation screen s4 in Figure 6D is displayed. The user presses the job start button b5 on the operation screen s4. As a result, the timing specification reception unit 115 of the image inspection device 100 receives an instruction to execute inspection by the image inspection unit 312 after the reference image generation by the reference image generation unit 311 is completed. The operation screen s5 shown in Figure 6E is the screen that is displayed following the operation screen s4 in Figure 6D. When the timing specification reception unit 115 receives an instruction to execute the inspection in the second inspection mode, the operation screen s5 is displayed.

[0072] Next, the first timing specification (part 2) will be explained with reference to Figures 6F to 6G. Buttons b2, b22, and b7 on the operation screen s7 in Figure 6G correspond to the first timing specification. The user selects buttons b2 and b22 on the operation screen s6 and then presses the selection button bb6. This causes a screen to pop up (not shown) where the user can specify the file path, and the user specifies a reference image file that was previously generated and registered. This reference image file is stored, for example, in the storage unit 32 (or storage unit 12). On the operation screen s7 in Figure 6G, the specified reference image (path to the reference image) is shown in the display field b60. The user presses the job start button b7 on the operation screen s7. As a result, the timing specification reception unit 115 of the image inspection device 100 receives an instruction to execute inspection by the image inspection unit 312 after the reference image generation by the reference image generation unit 311 has completed. When the job start button b7 on the operation screen s7 is pressed, the operation screen s5 is displayed, indicating that the instruction to execute the inspection in the second inspection mode has been received. Next, referring to Figures 7 to 9, the image inspection in accordance with the setting of inspection conditions and execution instructions for the image inspection received through the operation screens from Figures 6A to 6G will be explained.

[0073] (Image examination method) Figures 7 to 9 are flowcharts showing the image inspection method.

[0074] (Step S11) The image inspection device 100 receives a print job. The print job includes the original image (print data), job settings such as inspection conditions, etc. In the following explanation, the original image will be described as including image data for multiple pages, from 1 to n pages, as in the example in Figure 4.

[0075] (Step S12) The control unit 11 of the image inspection device 100 determines whether or not an inspection is set by referring to the inspection conditions described in the job settings. If the control unit 11 decides to perform the inspection (YES), it proceeds to step S13; if it decides not to perform the inspection (NO), it terminates the process (end). In this case, normal image forming is performed on the print job without image inspection, and the explanation is omitted.

[0076] (Step S13) The control unit 11 of the image inspection device 100 determines the generation timing of the reference image received by the timing specification reception unit 115. If the specification received by the timing specification reception unit 115 by the user is for the first inspection mode and the generation timing of the reference image is for the second timing, the process proceeds to Figure 8 (indicated by the circled "A" in the figure). On the other hand, if the specification received by the timing specification reception unit 115 by the user is for the second inspection mode and the first timing, the process proceeds to Figure 9 (indicated by the circled "B" in the figure). An inspection execution instruction accompanied by the specification of the second timing is the execution instruction received on the operation screen s1 in Figure 6A as described above, and is for the first inspection mode. An inspection execution instruction accompanied by the specification of the first timing is the execution instruction received on the operation screens s3, s4 in Figures 6C to 6D, or on the operation screens s6, s7 in Figures 6F to 6G as described above, and is for the second inspection mode.

[0077] Refer to Figure 8A. In Figure 8A (and similarly in Figure 9), the processes enclosed by the dashed line on the left are processes performed on the image forming apparatus 10 side, and the processes enclosed by the dashed line on the right are processes performed on the inspection unit 30 side. The processes on the image forming apparatus 10 side in steps S21 to S23 and the processes on the inspection unit side in steps S24 to S26 may be performed in parallel. That is, image formation by the image forming unit 16 and the generation of the reference image by the reference image generation unit 311 are performed simultaneously. For example, as shown in Figure 5, the generation of the reference images for pages 3 and 4 by the reference image generation unit 311 is performed in parallel with the formation of the inspection image for page 1 by the image forming unit 16. Also, the processes in step S25 and steps S27 and S28 may be performed in parallel. For example, as shown in Figure 5, in step S25, the reference image generation unit 311 generates the reference image for page 5, and at the same time, in step S27, the paper to be inspected is read, and in step S28, the inspection image is inspected by the image inspection unit 312.

[0078] (Step S21) The image forming unit 16 of the image forming apparatus 10 receives original images (1 to n).

[0079] (Step S215) The control unit 31 performs a reference image generation completion determination process 1 (hereinafter referred to as the determination process or determination process 1, etc.) before image inspection (step S28). Figure 8B is a subroutine flowchart showing the determination process. The determination process described here will be explained later.

[0080] (Step S22) The image forming unit 16 forms an image on the paper based on the original image. x is a value that starts at 1 and increments up to page n. The image forming unit 16 forms images on the paper sequentially from page 1 to page n. x is the current page value. The control unit 11 (or control unit 31) may also configure the image forming unit 16 to perform image formation after generating reference images for all pages (pages 1 to n).

[0081] (Step S23) The image forming apparatus 10 forms an image on a sheet of paper and then transports the image-formed paper to the inspection unit 30.

[0082] (Step S24) The inspection unit 30 receives the document image. The control unit 31 stores the received document image in the page memory or storage unit 32.

[0083] (Step S25) The reference image generation unit 311 generates a reference image based on the original image. Figure 10 is a subroutine flowchart showing the reference image generation process.

[0084] (Step S601) The reference image generation unit 311 reads out the original image stored in the page memory or storage unit 32.

[0085] (Step S602) The reference image generation unit 311 performs resolution conversion and color gamut conversion processing on the original image to obtain converted image data (a temporary reference image). This image data becomes the reference image after processing in steps S603 to S605 below.

[0086] (Step S603) The reference image generation unit 311 proceeds to step S603 if inspection area specification information is available (YES), and skips step S603 if it is not available (NO). Thus, inspection area specification information is not necessarily used in all image inspections and may be omitted. Inspection area specification information is included in the inspection condition information. As mentioned above, inspection area specification information includes the specification of the inspection area and the specification of areas to be excluded from inspection.

[0087] (Step S604) The reference image generation unit 311 sets the inspection area specification information in the reference image.

[0088] (Step S605) The reference image generation unit 311 extracts alignment features from the reference image. These alignment features include image contour information and edge information. This completes the process shown in Figure 10, and the process returns to its original state (return).

[0089] (Step S26) Refer to Figure 8 again. Here, if the entire page has not been completed, the control unit 31 increments x and performs the process of step S25 for the next page. On the other hand, if the entire page has been completed (YES), that is, if the generation of reference images up to the nth page (x=n) has been completed, the process proceeds to the next step S265. As described above, it is also possible to perform the process of step S25 in parallel with the processes of steps S27 and S28.

[0090] (Step S265) Here, the control unit 31 performs the determination process 2 before the image inspection (step S28).

[0091] (Step S501) The control unit 31 determines whether the reference image for page x is stored in the storage unit 32. If the control unit 31 determines that the reference image for page x has already been generated and stored in the storage unit 32 (YES), it terminates the process in Figure 8B and returns to the process in Figure 8A. If the determination process in step S215 is 1, the control unit 31 executes the processes from step S22 onwards; if the determination process in step S265 is 2, it executes the processes from step S27 onwards. On the other hand, if the reference image is not stored in the storage unit 32, the control unit 31 proceeds to step S502. This situation occurs because there are cases where the generation of the reference image is not completed in time. This is due to the following reasons: The processing time for generating the reference image varies depending on the content of the original image and the amount of inspection area specification information. Therefore, the processing time for generating the reference image may be longer than the image formation processing time. As another example, the determination here may be to determine whether the reference image for page x has already been generated and prepared.

[0092] (Step S502) The control unit 31 and the main unit control unit 11 perform processing according to the determination process.

[0093] If the determination process 1 is performed, the main unit control 11 causes the image forming apparatus 10 to wait for image formation on page x. For example, the image forming apparatus 10 may delay the paper feeding timing or stop the paper for a predetermined amount of time using the registration roller in the image forming unit 16. In addition, the operation panel 17 or the like will display that a waiting process has occurred and that the system is in a waiting state.

[0094] If the process goes through judgment process 2, the control unit 31 determines that the image on page x, which cannot be inspected, has already been formed on the paper or is in the process of being formed, and therefore treats page x as waste paper. The control unit 11 performs a purge process on page x, ejecting it to the purge tray using the purge device 40. The control unit 11 also performs a recovery print on this page x. Furthermore, the control unit 11 displays an error message, such as that waste paper has been generated, on the operation panel 17 or the like.

[0095] (Step S27) The image reading unit 33 of the inspection unit 30 reads the paper to be inspected (page x) transported from the image forming apparatus 10 and generates a read image. This read image is used as the inspection image.

[0096] (Step S28) The image inspection unit 312 performs an inspection on the x-th page inspection image that was read and generated in step S27. Figure 11 is a subroutine flowchart showing the image inspection process.

[0097] (Step S701) The image inspection unit 312 reads the reference image of page x stored in the storage unit 32 or page memory.

[0098] (Step S702) The image inspection unit 312 aligns the reference image on page x with the inspection image on the same page x generated in step S27. The alignment is performed by associating (matching) the features of the reference image extracted in step S604 with the features of the inspection image. Based on the feature matching, the image inspection unit 312 aligns the two images by coordinate transformation or coordinate shift.

[0099] (Steps S703, S704) The image inspection unit 312 takes the difference between the corresponding pixel values ​​of the reference image after alignment and the inspection image, and determines whether the inspection image is good or bad according to the size of the difference. With this, the process in Figure 11 is completed and the system returns to the original process (return).

[0100] (Step S29) Refer to Figure 8 again. Here, the image inspection device 100 increments x if not all pages have been completed and repeats the process from step S22 onwards. On the other hand, if all pages have been completed (YES), that is, if the inspection up to page n (x=n) has been completed, the process ends (END). This completes the image inspection process in the first inspection mode. Next, refer to Figure 9 and we will explain the second inspection mode.

[0101] (Second inspection mode) Figure 9 is a flowchart showing the second inspection mode, which follows Figure 7. The second inspection mode shown in Figure 9 is described assuming that the first timing specification and the instruction to perform image inspection based on those conditions, as explained in Figures 6C to 6E, have been received. In other words, in Figure 9, which will be explained below, a new reference image is registered, and then image inspection is performed using this image.

[0102] (Steps S41, S42) The inspection unit 30 receives the document image. The control unit 31 stores the received document image in the storage unit 32.

[0103] (Steps S43, S44) The reference image generation unit 311 generates a reference image based on the original image. The processing here is the same as in steps S25 and S26, and the reference image is generated according to the subroutine flowchart shown in Figure 10. When the generation of the reference image is complete, the timing specification reception unit 115 displays the operation screen s4 as shown in Figure 6D.

[0104] (Step S45) The timing specification reception unit 115 proceeds to step S46 if it receives an instruction to start the image inspection (YES). Here, the instruction to start the inspection is when the user presses the job start button d5 on the operation screen s4. This corresponds to receiving the specification of the first timing, in which the reference image generation unit 311 generates a reference image before image formation.

[0105] (Steps S46-S51) The process of transporting the image-formed paper from the image forming apparatus 10 to the inspection unit 30 is the same as steps S21 to S23 in Figure 8, and therefore the explanation is omitted.

[0106] (Steps S49-S50) The image inspection processing performed by the inspection unit 30 here is the same as the processing in steps S27 to S29 of Figure 8, and therefore the explanation is omitted.

[0107] As described above, the image inspection apparatus according to this embodiment includes a reference image generation unit that generates a reference image used for inspecting an image formed on a recording medium, an image inspection unit that inspects the image formed on the recording medium based on the reference image, and a reception unit that receives a specification for the timing of reference image generation. It also includes a control unit that controls the generation of the reference image by the reference image generation unit based on the received generation timing. As a result, the time required for processing up to image inspection can be shortened by specifying the timing of reference image generation. In particular, if the timing of reference image generation is specified as a second timing during image formation, the time required for processing up to image inspection can be shortened.

[0108] The configuration of the inspection unit 30 and the image inspection apparatus 100 equipped therewith described above is described as the main configuration in order to explain the features of the above embodiment, and is not limited to the above configuration, and can be modified in various ways within the scope of the claims. Furthermore, it does not exclude the configurations that are generally found in image forming apparatuses. The scope of the present invention should be interpreted in accordance with the attached claims.

[0109] (modified version) The image inspection device 100 may include a terminal device 80 equipped with a display unit. This terminal device 80 is provided with a timing specification reception unit 115, which receives the specification of the reference image formation timing and the instruction to execute the inspection via operation screens s1, s3, etc., displayed on the display unit.

[0110] Furthermore, the means and methods for performing various processing in the inspection unit 30 and image inspection apparatus 100 according to the above-described embodiment can be implemented by either a dedicated hardware circuit or a programmed computer. The program may be provided, for example, on a computer-readable recording medium such as a USB memory or DVD (Digital Versatile Disc)-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 and stored in a storage unit such as a hard disk. The program may also be provided as a standalone application software, or it may be incorporated into the software of the device as a function of the device. [Explanation of Symbols]

[0111] 1000 Printing Systems 100 Image inspection devices 10 Image forming apparatus 11 Main Unit Control 111 Printer Control Unit 112 Inspection Unit Control Unit 113 Other device control unit 115 Inspection Execution Instruction Reception Department 116 Data transmission unit 117 Inspection Area Reception Department 12 Storage section 13 Print Controller 14 Paper feed section 15 Conveying section 16 Image forming unit 17. Control Panel 19 Communications Department 20 Paper feeder 30 Inspection Units 31 Control Unit 311 Reference Image Generation Unit 312 Imaging Inspection Department 32 Storage section 33 Image reading unit 34 Conveying section 39 Communications Department 40. Purge device 50 Post-processing equipment

Claims

1. An image forming unit that forms an image on a recording medium based on an original image, A reference image generation unit that generates a reference image used 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 aforementioned reference image, A control unit controls the parallel execution of a reference image generation step, which includes the generation of a reference image by the reference image generation unit, an inspection step, which includes 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. A reception unit that accepts the specification of the timing for generating the reference image, It has, Image inspection device, in which, upon receiving an execution instruction for a print job corresponding to the aforementioned original image, the receiving unit receives a specification from the user regarding the timing of generation of the reference image.

2. The image inspection apparatus according to claim 1, wherein the control unit controls the generation of a reference image by the reference image generation unit according to the generation timing received by the reception unit.

3. The image inspection apparatus according to claim 1, wherein the generation timing includes a first timing which is before image formation by the image forming unit, and a second timing which is different from the first timing.

4. The image inspection apparatus according to claim 3, wherein the second timing includes the timing during image formation by the image forming unit.

5. The control unit controls the transmission of the original image to the reference image generation unit and the image forming unit based on the receipt of the second timing specification. The image inspection apparatus according to claim 3 or 4.

6. The image inspection apparatus according to claim 5, wherein the control unit controls the reference image generation process and the inspection process to be executed in parallel based on the receipt of the second timing specification.

7. The control unit controls the generation of the reference image by the reference image generation unit according to the generation timing received by the reception unit, When the control unit receives the second timing specification, When the image inspection unit performs an inspection on a sheet of paper for which an image has been formed based on the original image of page x out of pages 1 to n, The image inspection apparatus according to claim 3 or claim 4, wherein the generation of the reference image for page x by the reference image generation unit is determined before the inspection of page x.

8. The control unit controls the generation of the reference image by the reference image generation unit according to the generation timing received by the reception unit, When the control unit receives the second timing specification, When the image inspection unit performs an inspection on a sheet of paper for which an image has been formed based on the original image of page x out of pages 1 to n, The image inspection apparatus according to claim 3 or 4, wherein the control unit determines, before inspecting page x, whether the reference image for page x has already been generated by the reference image generation unit and whether the storage of the reference image in the storage unit has been completed.

9. The control unit controls the generation of the reference image by the reference image generation unit according to the generation timing received by the reception unit, When the control unit receives the first timing specification, The image inspection apparatus according to claim 3 or claim 4, wherein, before forming an image by the image forming unit, it is determined whether or not a registered reference image to be used for inspection by the image inspection unit has been specified.

10. A reference image generation step for generating a reference image used for inspecting an image formed on a recording medium, An image inspection step includes: forming an image on a recording medium based on an original image using an image forming unit; reading the recording medium on which the image has been formed to generate a read image; and inspecting the image formed on the recording medium based on the reference image. A reception step that accepts the specification of the timing for generating the reference image in the aforementioned reference image generation step, Includes, The aforementioned reference image generation step and the aforementioned image inspection step are performed in parallel. An image inspection method in which, upon receiving an execution instruction for a print job corresponding to the aforementioned original image, the reception step includes receiving a specification from the user for the timing of generation of the reference image.

11. The image inspection method according to claim 10, wherein the generation of the reference image in the reference image generation step is controlled according to the generation timing received in the reception step.

12. The image inspection method according to claim 10, wherein the generation timing includes a first timing which is before image formation by the image forming unit, and a second timing which is different from the first timing.

13. The image inspection method according to claim 12, wherein the second timing includes the timing during image formation by the image forming unit.

14. The image inspection method according to claim 12, wherein the reference image generation step and the image inspection step are executed in parallel based on the receipt of the second timing specification in the reception step.

15. The generation of the reference image in the reference image generation step is controlled according to the generation timing received in the reception step, If the second timing specification is received in the aforementioned reception step, In the aforementioned image inspection step, when an inspection is performed on a sheet of paper for which an image has been formed based on the original image of page x out of pages 1 to n, The image inspection method according to claim 12, further comprising a determination step of determining whether the generation of the reference image for page x in the reference image generation step has been completed, before inspecting page x.

16. The generation of the reference image in the reference image generation step is controlled according to the generation timing received in the reception step, If the second timing specification is received in the aforementioned reception step, In the aforementioned image inspection step, when an inspection is performed on a sheet of paper for which an image has been formed based on the original image of page x out of pages 1 to n, The image inspection method according to claim 12, further comprising a determination step of determining, before inspecting page x, whether the reference image for page x in the reference image generation step has already been generated and whether the storage of the reference image in the storage unit has been completed.

17. The generation of the reference image in the reference image generation step is controlled according to the generation timing received in the reception step, If the first timing specification is received in the reception step, The image inspection method according to claim 12, further comprising a determination step of determining whether a registered reference image to be used for inspection in the image inspection step has been specified, before the image forming unit forms the image.

18. An image inspection program for causing a computer to execute the image inspection method described in any one of claims 10 to 17.

Images