Image inspection apparatus, 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 a 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 the reference image, in the case of the proof mode for confirming the completion, image data derived from the original image used for printing is used, and in the subsequent actual printing, in the proof mode, when a printed matter confirmed by the user to have no abnormality visually is read, the read image data obtained 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 leading to the generation of the reference image used for actual printing is complicated, and it is necessary to prepare the reference image in advance and then execute the actual 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 prior art.

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 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, A reception unit that receives a designation of the generation timing of the reference image, An image inspection apparatus having the above.

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

[0009] (3) Further comprising an image forming unit that forms the image on the recording medium based on a document image, The generation timing includes a first timing before image formation by the image forming unit and a second timing different from the first timing. The image inspection apparatus according to (1) above.

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

[0011] (5) A control unit that controls to transmit the document image to the reference image generation unit and the image forming unit based on receiving the designation of the second timing, 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 generation of the reference image by the reference image generation unit and the formation of the image on the recording medium by the image forming unit to be performed in parallel.

[0013] (7) Having a control unit that controls 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 designation of the second timing, When performing an inspection on a sheet on which an image is formed based on the manuscript image of the x-th page out of 1 to n pages by the image inspection unit, The image inspection apparatus according to (3) or (4) above, which determines, before the inspection of the x-th page, whether or not the generation of the reference image of the x-th page by the reference image generation unit has been completed.

[0014] (8) It has 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, When the control unit receives the designation of the second timing, When performing an inspection on a sheet on which an image is formed based on the manuscript image of the x-th page out of 1 to n pages by the image inspection unit, The control unit determines, before the inspection of the x-th page, whether or not the reference image of the x-th page by the reference image generation unit has already been generated and the storage of the reference image in the storage unit has been completed. The image inspection apparatus according to (3) or (4) above.

[0015] (9) It has 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, When the control unit receives the designation of the first timing, Before the image forming unit forms an image, it determines whether or not a registered reference image used for the inspection by the image inspection unit has been designated. The image inspection apparatus according to (3) or (4) above.

[0016] (10) A reference image generation step of generating 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 reference image, A reception step of receiving the designation of the generation timing of the reference image in the reference image generation step, An image inspection method including:

[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 designation of the generation timing of the reference image in the reference image generation step, and an image inspection program for causing a computer to execute a process including these steps.

Advantages 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 designation 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

Figure 2

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Figure 4

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Figure 6A

Figure 6B

Figure 6C

Figure 6D

Figure 6E

Figure 6F

Figure 6G

Figure 7

Figure 8A

Figure 8B

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Figure 10

Figure 11

Mode for Carrying Out the Invention

[0020] Hereinafter, embodiments of the present invention will be described 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 duplicate descriptions are omitted. The advantages and features provided by one or more embodiments of the present invention will be fully understood from the following detailed description and the attached drawings. Also, the attached drawings are provided for illustrative purposes only and are not intended to define the scope of the present invention.

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

[0022] The terminal device 80 can be, for example, a personal computer, a tablet terminal, a smartphone, or the like. A printer driver for converting original data into a print job is installed in the terminal device 80. The terminal device 80 is used by a user such as an operator who operates the image inspection apparatus 100. The printer driver generates a print job in a format that can be handled by a print controller 13 (see FIG. 2 described later) of the image inspection apparatus 100 according to a user's instruction, and transmits the print job to the image inspection apparatus 100 through the network 90. Further, the terminal device 80 includes a display and can display inspection results (inspection results) (good / defective) of printed matter, images of defective printed matter, and the like.

[0023] A print job includes, for example, print data in the 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, 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, etc. The job settings also include inspection conditions. The inspection conditions include the presence or absence of image inspection (inspection setting on / off), and when there is "image inspection", further include the types of the first and second inspection modes. The inspection conditions may also include inspection area designation information (described later). Further, in the second inspection mode, path information (file directory information) for designating the file of the registered reference image to be used is included. The user can issue an instruction for image inspection to the printing system 1000 by setting "with inspection" (turning on the inspection setting). The inspection conditions can be set through an operation screen (for example, FIG. 6A etc. described later) displayed by the printer driver.

[0024] (Image inspection device 100) The image inspection device 100 is also referred to as an image forming system. The image inspection device 100 includes an image forming device 10, a paper feeding device 20, an inspection unit 30, a purge device 40, and a post-processing device 50 that are mechanically and electrically connected to each other.

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

[0026] (Image forming apparatus 10) The image forming apparatus 10 performs image formation on the paper fed from the paper feeding apparatus 20 on the upstream side and conveyed. Also, the image forming apparatus 10 performs image formation on the paper fed from the paper feeding unit of its own apparatus.

[0027] As shown in FIG. 2, the image forming apparatus 10 includes a main control unit 11, a storage unit 12, a print controller 13, a paper feeding unit 14, a conveyance 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 a bus for signal exchange. In FIG. 2, the connection lines to some components such as the storage unit 12 and the print controller 13 in the image forming apparatus 10 are omitted. Similarly, in the inspection unit 30, the connection lines between some components are omitted.

[0028] (Main control unit 11) The main control unit 11 is composed of a CPU, a ROM, a RAM, etc., and executes various processes by executing the programs stored in the ROM and the storage unit 12 described later, and performs control of each part of the apparatus and various arithmetic processes according to the programs. The main control unit 11 functions as a printer control unit 111, an inspection unit control unit 112, an other apparatus control unit 113, a timing designation reception unit 115, a data transmission unit 116, and an inspection area reception unit 117. The details of each sub-function will be described later. The main control unit 11 cooperates with the control unit 31 etc. of the inspection unit 30 to control the entire image inspection apparatus 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 various data in advance. Also, the storage unit 12 functions as a page memory (the same applies to the storage unit 32 described later).

[0030] (Print controller 13) The print controller 13 analyzes the print job received from the terminal device 80 through the network 90, executes processes such as color conversion, screening, and rasterization, and generates a manuscript image in bitmap format. The generated manuscript image is transmitted to the control unit 31. The print controller 13 functions as a manuscript image acquisition unit.

[0031] The print controller 13 receives a print job from the terminal device 80 or the like via the communication unit 19. The received print job includes print data (mainly in PDL format) that is the source of the manuscript image (also referred to as manuscript image data) and job information describing print settings such as the type of paper to be used. The print controller 13 performs rasterization (RIP) processing to convert the print data into page-based bitmap data based on the print settings. The RIP image after the rasterization processing 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 in 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 a manuscript image via the write processing unit, and printing is executed.

[0032] (Paper feeding unit 14, conveying unit 15) The paper feeding unit 14 includes a plurality of paper feeding trays. The conveying unit 15 includes a conveying path. This conveying path includes a plurality of pairs of conveying rollers provided along the conveying path and a drive motor (not shown) for driving these pairs of conveying rollers. The paper feeding unit 14 includes a feeding roller that feeds out the uppermost sheet among the plurality of sheets stacked and placed in the paper feeding tray, and feeds out the sheets in the paper feeding tray one by one to the downstream conveying path.

[0033] (Image forming unit 16) The image forming unit 16 forms an image by, for example, an electrophotographic method. The image forming unit 16 includes a writing unit (laser exposure unit) corresponding to each of the basic colors of Y (yellow), M (magenta), C (cyan), and K (black), a photosensitive drum, and a developing device that houses a two-component developer composed of toner and carrier for each color, etc. Further, the image forming unit 16 further includes an intermediate transfer belt, a secondary transfer unit, and a fixing unit. The toner images formed on the photosensitive drum by the developing devices of each color are superimposed on the intermediate transfer belt and transferred to the paper conveyed in the secondary transfer unit. The toner image on the paper is fixed on the paper by being heated and pressurized by the fixing unit on the downstream side.

[0034] (Operation panel 17) The operation panel 17 includes a touch screen, numeric keys, a start button, a stop button, etc. The operation panel 17 displays the state of the image forming apparatus 10 or the image inspection apparatus 100 and is used for inputting various settings and instructions from the user. Further, the inspection result by the inspection unit 30 is displayed, and the setting of inspection conditions and the input of execution instructions are received.

[0035] (Communication unit 19) The communication unit 19 is an interface for communicating with each device such as a PC on the network or other devices 20, 30, etc.

[0036] (Sub - functions 111 to 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 setting) of the input print job. The print job is input by an instruction sent from the operation panel 17 or a terminal device 80 such as a network - connected PC operated by the user. Further, the job setting includes print settings and inspection conditions. The print settings include double - sided / single - sided, print paper type, post - processing conditions, etc. Details of the inspection conditions will be described later. For example, they are set by an operation screen such as FIG. 6A described later.

[0037] The printer control unit 111 controls the paper feeding and conveyance of the paper by controlling the paper feeding unit 14 and the conveyance unit 15. Further, the printer control unit 111 controls the image forming unit 16 to form an image on the paper under 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 feeding device 20, the purge device 40, and the post-processing device 50. Specifically, the other device control unit 113 communicates with the paper feeding device 20 to transmit and receive the paper feeding tray to be used, the paper conveyance timing, etc. The other device control unit 113 transmits to the purge device 40 the paper conveyance timing, the designation of the main and sub conveyance paths of the paper to be conveyed, and the setting information of the post-processing to the post-processing device 50, etc.

[0040] (Timing Designation Reception Unit 115) The timing designation reception unit 115 receives the designation of the generation timing of the reference image. The main body control unit 11 controls the generation or the generation timing of the reference image by the reference image generation unit 311 based on the received generation timing. The generation timing includes a first timing and a second timing different from the first timing. The first timing is before the image formation by the image forming apparatus 10 (or the image forming unit 16). The second timing is, for example, during the image formation. More specifically, when generating an image formation and a reference image based on a plurality of pages of original images, the generation of the reference image is started during the image formation. The image formation in progress means that, among a plurality of pages of original images, after the paper feeding by the paper feeding unit 14 of the paper for forming the image on the first page starts, until the image formation by the image forming unit 16 for the paper of the last page ends and the image forming unit 16 is exited. An example of the first timing will be described later (Fig. 5).

[0041] (First Inspection Mode, Second Inspection Mode) In the embodiments described below, the image inspection in which the generation timing of the reference image is the first timing corresponds to the second inspection mode. Also, the image inspection in which the generation timing of the reference image is the second timing corresponds to the first inspection mode. An example of accepting the first and second inspection modes will be described later (FIGS. 4A, etc.).

[0042] In the first inspection mode, it can be said that an inspection execution instruction can be received before the generation of the reference image is completed. In the first inspection mode, in parallel with the image formation process of the inspection target image on the paper by the image formation unit 16 based on the manuscript image, the reference image generation process by the reference image generation unit 311 based on the same manuscript image is executed.

[0043] In the second inspection mode, it can be said that an inspection execution instruction can be received after the reference image generation process is completed. In the second inspection mode, the reference image generation process by the reference image generation unit 311 is executed based on the manuscript image, and then the inspection is performed by receiving an inspection execution instruction using this. Alternatively, in the second inspection mode, an inspection using a previously registered reference image is executed. The latter includes both the case of newly generating and registering a reference image for inspection and the case of reusing a previously registered reference image.

[0044] (Data transmission unit 116) The data transmission unit 116 transmits the manuscript image to the image formation unit 16 and the inspection unit 30 (particularly the reference image generation unit 311). In particular, the data transmission unit 116 transmits the manuscript image to the image formation unit 16 and the inspection unit 30 (particularly the reference image generation unit 311) in response to receiving an inspection execution in the first inspection mode. For example, in response to receiving an inspection execution in the first inspection mode, the data transmission unit 116 immediately transmits the manuscript image to both the image formation unit 16 and the reference image generation unit 311 at the same time. Also, the data transmission unit 116 transmits the manuscript image to the image formation unit 16 in response to receiving an inspection execution in the first inspection mode. Further, the data transmission unit 116 transmits the manuscript image to the image formation unit 16 in response to receiving an inspection execution in the second inspection mode by the second reception unit.

[0045] (Inspection Area Reception Unit 117) The inspection area reception unit 117 receives (a) the designation of an inspection exclusion area and (b) the designation of an inspection area (hereinafter, these are collectively referred to as "inspection area designation information"). Further, the inspection area reception unit 117 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 positions along the main scanning direction (X direction) and the sub-scanning direction (Y direction)) and its content. The area range is, for example, a rectangular area. The area designated as (a) the inspection exclusion area is excluded from inspection. The area designated as (b) the inspection area is the inspection target. In the area designated as the inspection area, it is also possible to perform inspections different from normal ones. For example, when a face photo image is included in the original image, the inspection level for color is set strictly in the area including the human skin of the face. Also, in the designation of the inspection area, there is a barcode designation. There may be a barcode (1D, 2D) included in the original image. In this case, in the inspection area where the barcode is designated, the printing of the barcode is inspected by decoding the image within the inspection area.

[0046] (Paper Feeding Device 20) The paper feeding device 20 shown in FIGS. 1 and 2 includes a paper feeding unit and a conveying unit similar to those of the image forming apparatus 10. Further, the paper feeding device 20 includes, in addition to the conveying unit and the paper feeding unit, a control unit, a storage unit, and a communication unit (none of which are shown), and these are interconnected via signal lines such as a bus for signal exchange.

[0047] (Inspection Unit 30) Next, the inspection unit 30 will be described. As shown in FIG. 2, the inspection unit 30 includes a control unit 31, a storage unit 32, an image reading unit 33, a conveying unit 34, a communication unit 39, etc. Each of the control unit 31, the storage unit 32, the conveying unit 34, and the communication unit 39 has the same hardware configuration as the main control unit 11, the storage unit 12, the conveying unit 15, and the communication unit 19 of the above-described image forming apparatus 10, and the description thereof will be omitted.

[0048] The image reading unit 33 reads a sheet (printed matter) being conveyed on the conveyance path, for example, by a CCD (Charge Coupled Device) image sensor. The control unit 31 controls the scanner to read an image (inspection image) formed on the sheet conveyed from the image forming apparatus 10 in accordance with a reading instruction from the inspection unit control unit 112. Further, the control unit 31 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 an independent CPU so that their respective reference image generation processes and image inspection processes can be performed in parallel. That is, the control unit 31 is configured with a plurality of CPUs. Alternatively, a multi-core CPU is applied as the CPU of the control unit 31. In the case of a multi-core CPU, the reference image generation unit 311 is assigned to a core different from the process of forming and inspecting the inspection image of the image inspection unit 312, and the generation of the reference image and the formation and inspection of the inspection image can be executed in parallel by different cores.

[0052] (Reference image generation unit 311) The reference image generation unit 311 performs various processes on the original image with respect to position, resolution, color, etc. to generate a reference image. For example, the reference image generation unit 311 can extract the position information of the content part from the original image so that the content parts of the reference image and the read image (inspection image) can be compared with each other, and can add or embed the position information in the reference image. That is, the reference image generated by the reference image generation unit 311 has alignment information (also referred to as an alignment feature amount) for aligning the reference image and the inspection image when performing image inspection based on the reference image. Note that the alignment information includes contour information and edge information of the image. Further, the reference image generated by the reference image generation unit 311 has region information regarding the inspection region and the inspection exclusion region based on the inspection region designation information received by the above-described inspection region reception unit 117. Furthermore, the reference image generation unit 311 can generate a reference image by adjusting the resolution of the original image so as to match the resolution of the image reading unit 33 (scanner). Also, the reference image generation unit 311 can generate a reference image by converting the color space of the original image data so as to match the color space (e.g., RGB) adopted by the image reading unit 33.

[0053] The reason why the reference image generation unit 311 does not use the original image as it is is as follows. Ideally, the read image (inspection image) generated by reading the image formed on the paper is considered to match the original image in terms of content. However, when reading the inspection image formed on the paper by a scanner, errors may occur in the inspection image with respect to the original 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. Also, errors may occur in the original image depending on the resolution of the scanner reading. Therefore, there is a high possibility of errors if the inspection image and the original image are simply compared, and it is not practical to inspect the inspection image by simply comparing it with the original image. Thus, in the present embodiment, the reference image generation unit 311 is configured to generate a reference image by performing various processes on the original image with respect to position, resolution, color, etc. so that it can be compared with the inspection image, and to compare the reference image with the inspection image. Thereby, since the comparison with the inspection image is appropriately performed, the inspection of the printed matter can be performed with high accuracy.

[0054] (Image inspection unit 312) The image inspection unit 312 performs image inspection based on the reference image. More specifically, the image inspection unit 312 acquires the reference image and the read image, and inspects the inspection image formed on the paper by comparing the reference image and the read image page by page.

[0055] FIG. 3 is a schematic diagram for explaining the process of image inspection. The image inspection unit 312, for example, calculates the difference (error) in pixel values between the reference image and the inspection 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, an inspection result of "good" is output, and if the total value of the differences is greater than or equal to the specified value, an inspection result of "bad" is output. Also, when calculating the difference object by object or region by region, it can be configured to output an inspection result of "good" or "bad" according to the total value of the differences of the pixel values within the selected object or region.

[0056] When the inspection result of the inspection image is "good", the control unit 31 determines that the printed matter is a good product. When the inspection result of the inspection image is "defective", the control unit 31 determines that the printed matter is a defective product. The determination result is sent to the main control unit 11.

[0057] (Purge device 40) The purge device 40 is provided with a branch portion of the conveyance path, and includes a main conveyance path leading to the post-processing device 50 and a sub-conveyance path leading to a purge tray (disposed above the purge device 40 in FIG. 1). For example, sheets determined to be of poor quality in the inspection by the inspection unit 30 are discharged to the purge tray.

[0058] (Post-processing device 50) The post-processing device 50 performs post-processing on or discharges the sheets sent from the upstream image forming device 10 according to the settings of the print job. The post-processing device 50 includes a paper discharge tray, a post-processing unit, and a conveyance path. The post-processing device 50 also includes a control unit, a storage unit, a conveyance unit, and a communication unit (none of which are shown in the figure), and these are interconnected via signal lines such as a bus for signal exchange. The post-processing unit performs at least one of staple processing, punching processing, cutting processing, folding processing, and bookbinding processing on the image-formed sheets.

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

[0060] The main control unit 11 acquires job settings (not shown) and the original manuscript image from the print controller 13. The original manuscript image is a RIP image obtained by rasterizing print data. The original manuscript image is stored in the page memory. The job settings include information such as inspection conditions and printing settings. The inspection conditions include the presence or absence of image inspection, and when the image inspection is "yes", the types of the first and second inspection modes are further included. Further, in the second inspection mode, path information (file directory information) for designating the file of the registered reference image to be used is included. In the example of FIG. 4, it is mainly described that the first inspection mode is selected as the job setting. Also, in the example of FIG. 4, it is described that the original manuscript image is composed of n print data from page 1 to page n.

[0061] In the case of the first inspection mode, the main control unit 11 (data transmission unit 116) simultaneously transmits the original manuscript 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 sequentially generates reference images 1 to n for pages 1 to n from the received original manuscript image (pages 1 to n), and stores them in the storage unit 32.

[0063] In FIG. 4, x has an initial value of 1 and is a value that increments up to the nth page. The image forming unit 16 forms an image on the paper in order from page 1 to page n. x is the current page value.

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

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

[0066] Here, when the timing designating reception unit 115 receives the execution of 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 forming unit 16 are executed in parallel. FIG. 5 is a schematic diagram showing the processes of acquiring the original image, generating the reference image, forming the inspection image, and inspecting the inspection image in chronological order when the second timing is designated. In FIG. 5, the following processes are shown in order from the top. (Process 1) Acquisition of the original image by the main body control unit 11. (Process 2) Generation of the reference image by the reference image generation unit 311. (Process 3) Formation of the image of the inspection target by the image forming apparatus 10 (image forming unit 16). (Process 4) Inspection using the inspection image and the reference image by the image inspection unit 312. Also, in FIG. 5, with n = 8, the processes of printing and inspecting the original images of a total of 8 pages are shown. Regarding processes 3 and 4, the description of the processes after 3 and 4P (pages) is omitted. In FIG. 5, during image formation, printing preparation is included. Here, the printing preparation includes paper feeding by the paper feeding device 20 or the paper feeding unit 14 for the paper of the first page, and data processing such as rasterization processing by the image forming apparatus 10.

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

[0068] (Image inspection method) Hereinafter, with reference to FIGS. 6A to 11, the image inspection method according to the present embodiment will be described.

[0069] First, the setting of the inspection conditions for the image inspection in the present embodiment will be described. FIGS. 6A to 6G are operation screens (operation screens s1 to s7) for setting the inspection conditions for the image inspection and giving an execution instruction. Regarding the print settings other than the inspection conditions for the print job job1 and the designation of the original image, they are performed on other operation screens (not shown). The 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 the operation screens s1, s3, etc., the user can select either of the radio buttons b1 and b2. Further, when the user selects b2, the user can further select either of b21 and b22.

[0070] (Second timing) With reference to FIGS. 6A to 6B, the designation of the second timing will be described. The buttons b1 (and b3) on the operation screen s1 in FIG. 6A correspond to the first reception unit. The user selects the button b1 on the operation screen s1 and presses the job start button b3. Thereby, the timing designation reception unit 115 of the image inspection apparatus 100 receives an execution instruction from the image inspection unit 312 before the generation of the reference image by the reference image generation unit 311 is completed (first inspection mode). By receiving the execution instruction, the image inspection apparatus 100 immediately executes image formation and inspection of the image generated thereby. The operation screen s2 shown in FIG. 6B is a screen displayed following the operation screen s1 in FIG. 6A. When the user presses the job start button b3, the timing designation reception unit 115 receives an execution instruction for the inspection in the first inspection mode. In response thereto, an operation screen s2 indicating that the first inspection mode has been received is displayed.

[0071] (First timing) Referring to FIGS. 6C to 6E, the designation of the first timing (Part 1) will be described. Buttons b2 (as well as b21 and b5 (operation screen s4)) on the operation screen s3 in FIG. 6C correspond to the designation of the first timing. The user selects button b2, further selects button b21, and presses the registration start button b4. As a result, the reference image generation unit 311 of the image inspection apparatus 100 newly generates a reference image based on the original image and registers the generated reference image in the storage unit 32 or the like. By registering, the operation screen s4 in FIG. 6D is displayed. The user presses the job start button b5 on the operation screen s4. As a result, after the reference image generation by the reference image generation unit 311 is completed, the timing designation reception unit 115 of the image inspection apparatus 100 receives an instruction to execute the inspection by the image inspection unit 312. The operation screen s5 shown in FIG. 6E is a screen displayed following the operation screen s4 in FIG. 6D. When the timing designation reception unit 115 receives an instruction to execute the inspection in the second inspection mode, the operation screen s5 is displayed.

[0072] Next, referring to FIGS. 6F to 6G, the designation of the first timing (part 2) will be described. Buttons b2, b22, and b7 on the operation screen s7 in FIG. 6G correspond to the designation of the first timing. The user selects buttons b2 and b22 on the operation screen s6 and further presses the selection button bb6. As a result, a screen for designating the file path of the file pops up (not shown), and the user designates the file of the reference image generated and registered in the past. This file of the reference image is stored, for example, in the storage unit 32 (or the storage unit 12). On the operation screen s7 in FIG. 6G, the designated reference image (the path of the reference image) is shown in the display column b60. The user presses the job start button b7 on the operation screen s7. As a result, after the generation of the reference image by the reference image generation unit 311 is completed, the timing designation reception unit 115 of the image inspection apparatus 100 receives an instruction to execute the inspection by the image inspection unit 312. Even when the job start button b7 on the operation screen s7 is pressed, an operation screen s5 indicating that an instruction to execute the inspection in the second inspection mode has been received is displayed. Next, referring to FIGS. 7 to 9, the image inspection according to the setting of the inspection conditions and the execution instruction of the image inspection received by the operation screens from FIGS. 6A to 6G will be described.

[0073] (Image inspection method) FIGS. 7 to 9 are flowcharts showing an image inspection method.

[0074] (Step S11) The image inspection apparatus 100 receives a print job. The print job includes a document image (print data) and job settings such as inspection conditions. In the following, it will be described as an example that the document image includes image data of a plurality of pages from page 1 to page n, similar to the example in FIG. 4.

[0075] (Step S12) The control unit 11 of the image inspection apparatus 100 determines the presence or absence of inspection settings by referring to the inspection conditions described in the job settings. When the control unit 11 executes the inspection (YES), the process proceeds to step S13. When the control unit 11 does not execute the inspection (NO), the process ends (END). In this case, normal image formation is performed without performing an image inspection on the print job, and the description is omitted.

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

[0077] Refer to Fig. 8A. In Fig. 8A (similarly in Fig. 9), the processes enclosed by the one-dot chain line on the left side are the processes performed on the image forming apparatus 10 side, and the processes enclosed by the chain line on the right side are the 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, the 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 Fig. 5, the generation of the reference image for pages 3 to 4 by the reference image generation unit 311 is performed in parallel with the formation of the inspection image for the first page by the image forming unit 16. Also, the process in step S25 and the processes in steps S27 and S28 may be performed in parallel. For example, as shown in Fig. 5, in step S25, the reference image generation unit 311 generates the reference image for the fifth page, and at the same time, in step S27, the paper to be inspected is read, and in step S28, the inspection of the inspection image is performed by the image inspection unit 312.

[0078] (Step S21) The image forming unit 16 of the image forming apparatus 10 receives the 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 the image inspection (step S28). Fig. 8B is a subroutine flowchart showing the determination process. The determination process here will be described later.

[0080] (Step S22) The image forming unit 16 forms an image on the paper based on the original image. x has an initial value of 1 and is a value that increments up to the nth page. The image forming unit 16 forms an image on the paper in order from pages 1 to n. x is the current page value. Note that the control unit 11 (or the control unit 31) may cause the image forming unit 16 to perform image formation after the generation of the 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 conveys the sheet of paper on which the image has been formed to the inspection unit 30.

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

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

[0084] (Step S601) The reference image generation unit 311 reads out the original image stored in the page memory or the 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 the converted image data (temporary reference image). This image data becomes the reference image by performing the processing of the following steps S603 to S605.

[0086] (Step S603) If the reference image generation unit 311 has the inspection area designation information (YES), the process proceeds to step S603. If not (NO), step S603 is skipped. Thus, the inspection area designation information is not necessarily used in all image inspections and may be omitted. The inspection area designation information is included in the inspection condition information. As the inspection area designation information, there are the designation of the inspection area and the designation of the inspection exclusion area as described above.

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

[0088] (Step S605) The reference image generation unit 311 extracts alignment feature amounts from the reference image. Examples of the alignment feature amounts include contour information and edge information of the image. Thus, the processing of FIG. 10 is completed, and the process returns to the original process.

[0089] (Step S26) Referring again to FIG. 8, here, if not all pages have been completed, the control unit 31 increments x and performs the process of step S25 for the next page. On the other hand, if all pages have been completed (YES), that is, if the generation of the reference images up to the n-th 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 determination process 2 before the image inspection (step S28).

[0091] (Step S501) The control unit 31 determines whether the reference image of the x-th page is stored in the storage unit 32. If the control unit 31 determines that the reference image of the x-th page has been generated and is stored in the storage unit 32 (YES), the process of FIG. 8B is terminated and the process returns to the process of FIG. 8A. If it is determination process 1 in step S215, the control unit 31 executes the processes from step S22 and below, and if it is determination process 2 in step S265, the control unit 31 executes the processes from step S27 and below. On the other hand, if the reference image is not stored in the storage unit 32, the control unit 31 proceeds the process to step S502. Such a situation may occur because the generation of the reference image may not be in time. This is due to the following reasons. The generation processing time of the reference image varies depending on the content of the manuscript image and the amount of inspection area designation information. Therefore, the generation processing time of the reference image may be longer than the image formation processing time. As another example, the determination here may be made to determine whether the reference image of the x-th page has already been generated and is ready.

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

[0093] When passing through the determination process 1, the main body control unit 11 causes the image forming apparatus 10 to perform a waiting process for image formation related to the x page. For example, the image forming apparatus 10 delays the paper feeding timing or stops the paper for a predetermined additional time with the registration roller in the image forming unit 16. Further, it displays on the operation panel 17 or the like that the waiting process has occurred and that it is in a waiting state.

[0094] When passing through the determination process 2, since the image of the x-th page for which image inspection cannot be performed has already been formed on the paper or is being formed, the control unit 31 makes the paper of the x-th page into waste paper. The control unit 11 performs a purge process of discharging the x-th page to the purge tray by the purge device 40. Further, the control unit 11 causes a recovery print for this x page to be executed. Further, the control unit 11 displays an error message such as the occurrence of waste paper 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 (x-th page) conveyed from the image forming apparatus 10 and generates a read image. This read image is used as an inspection image.

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

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

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

[0099] (Steps S703, S704) The image inspection unit 312 takes the difference between the corresponding pixel values of the reference image and the inspection image after alignment, and determines the quality of the inspection image according to the magnitude of the difference. Thus, the processing of FIG. 11 is terminated and the process returns to the original process.

[0100] (Step S29) Referring to FIG. 8 again. Here, if the image inspection apparatus 100 has not completed all pages, it increments x and repeats the processing below step S22. On the other hand, if all pages have been completed (YES), that is, if the inspection up to the n-th page (x = n) has been completed, the process ends (ends). The above is the image inspection process in the first inspection mode. Next, referring to FIG. 9, the second inspection mode will be described.

[0101] (Second inspection mode) FIG. 9 is a flowchart showing the second inspection mode performed following FIG. 7. The second inspection mode shown in FIG. 9 will be described on the assumption that the designation of the first timing described in FIGS. 6C to 6E and the execution instruction of the image inspection based on the condition are received. That is, in FIG. 9 described below, a reference image is newly registered, and then the image inspection using this is performed.

[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 manuscript image. The processing here is the same as that in steps S25 and S26, and the reference image is generated according to the subroutine flowchart shown in FIG. 10. When the generation of the reference image is completed, the timing specification reception unit 115 displays an operation screen s4 as shown in FIG. 6D.

[0104] (Step S45) If there is an instruction to start the execution of the image inspection (YES), the timing specification reception unit 115 proceeds to step S46. Here, the instruction to start the execution means that the job start button d5 is pressed by the user on the operation screen s4. This corresponds to receiving the specification of the first timing for generating the reference image by the reference image generation unit 311 before image formation.

[0105] (Steps S46 - S51) The process of transporting the paper on which the image is formed by the image forming apparatus 10 to the inspection unit 30 here is the same as the process in steps S21 - S23 of FIG. 8, and the description is omitted.

[0106] (Steps S49 - S50) The image inspection process and the like by the inspection unit 30 here are the same as the process in steps S27 - S29 of FIG. 8, and the description is omitted.

[0107] As described above, the image inspection apparatus according to the present 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 the specification of the generation timing of the reference image. Further, it includes a control unit that controls the generation of the reference image by the reference image generation unit based on the received generation timing. Thereby, by specifying the generation timing of the reference image, the time required for the process leading to image inspection can be shortened. In particular, as the second timing, when the generation timing of the reference image is specified during image formation, the time required for the process leading to image inspection can be shortened.

[0108] The configurations of the inspection unit 30 described above and the image inspection apparatus 100 including the same have been described mainly for explaining the features of the above-described embodiment, and are not limited to the above configurations. Within the scope of the claims, various modifications can be made. Also, the configurations included in a general image forming apparatus are not excluded. The scope of the present invention should be construed by the appended claims.

[0109] (Modification example) The image inspection apparatus 100 may include a terminal device 80 having a display unit. The terminal device 80 is provided with a timing specification reception unit 115, and receives a specification of the reference image formation timing and an inspection execution instruction through operation screens s1, s3, etc. displayed on the display unit.

[0110] Also, the means and methods for performing various processes in the inspection unit 30 and the image inspection apparatus 100 according to the above-described embodiment can be realized by either a dedicated hardware circuit or a programmed computer. The above program may be provided by a computer-readable recording medium such as a USB memory or a DVD (Digital Versatile Disc)-ROM, 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 storage unit such as a hard disk. Also, the above program may be provided as a single application software, or may be incorporated into the software of the apparatus as one function of the apparatus.

Explanation of reference numerals

[0111] 1000 Printing system 100 Image inspection apparatus 10 Image forming apparatus 11 Main body control unit 111 Printer control unit 112 Inspection unit control unit 113 Other device control unit 115 Inspection execution instruction reception unit 116 Data transmission unit 117 Inspection area reception unit 12 Memory unit 13 Print controller 14 Paper feeding unit 15 Conveying unit 16 Image forming unit 17 Operation panel 19 Communication unit 20 Paper feeding device 30 Inspection unit 31 Control unit 311 Reference image generation unit 312 Image inspection unit 32 Memory unit 33 Image reading unit 34 Conveying unit 39 Communication unit 40 Purge device 50 Post-processing device

Claims

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 an image formed on the recording medium based on the reference image, A reception unit that receives a designation of the generation timing of the reference image, An image inspection apparatus having the above.

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

3. Further comprising an image forming unit that forms the image on the recording medium based on a document image, The image inspection apparatus according to claim 1, wherein the generation timing includes a first timing before image formation by the image forming unit and a second timing different from the first timing.

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

5. A control unit that controls to transmit the document image to the reference image generation unit and the image forming unit based on receiving a designation of the second timing, The image inspection apparatus according to claim 3 or 4, further comprising the above.

6. The image inspection apparatus according to claim 5, wherein the control unit causes the generation of the reference image by the reference image generation unit and the formation of the image on the recording medium by the image forming unit to be performed in parallel.

7. Having a control unit that controls 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 a designation of the second timing, When the image inspection unit inspects a sheet on which an image is formed based on a document image on the x-th page out of 1 to n pages, The image inspection apparatus according to claim 3 or claim 4, wherein it is determined before inspection of the x-th page whether generation of the reference image for the x-th page by the reference image generation unit is completed.

8. Having a control unit that controls 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 a designation of the second timing, When the image inspection unit inspects a sheet on which an image is formed based on a document image on the x-th page out of 1 to n pages, The control unit according to claim 3 or claim 4 determines, before inspecting the x-th page, whether the reference image for the x-th page 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. It has 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. When the control unit receives the designation of the first timing, The image inspection apparatus according to claim 3 or claim 4 determines whether a registered reference image to be used for inspection by the image inspection unit is specified before an image is formed by the image forming unit.

10. A reference image generation step of generating a reference image 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 reference image; A reception step of receiving the designation of the generation timing of the reference image in the reference image generation step; An image inspection method including the above steps.

11. A reference image generation step of generating a reference image 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 reference image; A reception step of receiving the designation 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 steps.

Images