JP2016177669A - Image inspection device, image inspection system and image inspection method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To more suitably perform setting of a threshold for determining a defect based on a comparison result than in a conventional manner in an inspection of an image by comparing an image obtained by reading an output result by image formation output with a master image.SOLUTION: An image inspection device generates an inspection image for performing an inspection of a read image based on an image for image formation output, determines a degree of difference showing size of a pixel value constituting a differential image showing difference between the generated inspection image and the read image, determines a defect of the read image based on the determined degree of difference and a threshold of the degree of difference, stores differential image information regarding the differential image whose degree of difference is determined in a storage medium, selects the predetermined number of differential images from among differential images shown by the differential image information stored in the storage medium based on the differential image information stored in the storage medium, classifies the selected differential images by the degree of difference to be presented, and sets the degree of difference selected based on presentation of the differential images as the threshold of the degree of difference.SELECTED DRAWING: Figure 12

Description

  The present invention relates to an image inspection apparatus, an image inspection system, and an image inspection method.

  Conventionally, inspection of printed matter has been performed manually, but in recent years, inspection apparatuses that inspect printed matter as post-processing of printing have been used. Such an inspection apparatus first generates a master image serving as a reference from print data. Then, the inspection apparatus compares the generated master image with the corresponding portion of the read image of the printed material to be inspected, and determines the defect of the printed material based on the degree of these differences.

  When determining a defect, it is necessary to set a threshold value such as a numerical value for the comparison result of the image or a level indicating the degree of difference. Since the setting of such a threshold is related to the accuracy of inspection, it is necessary to set an appropriate threshold in order to perform a highly accurate inspection.

  For the purpose of setting an appropriate threshold, a defect image obtained by adding a pseudo defect having a different degree of defect to the original image is presented to the user, and the threshold is set according to the selection of the defect image by the user. It has been proposed (see, for example, Patent Document 1).

  However, the defect image to which the pseudo defect is added lacks reality, and there may be a gap with the actually generated defect, and the inspection accuracy is insufficient with the threshold set by the technique disclosed in Patent Document 1. There is a case. In addition, when using a defect image that includes defects that have actually occurred, there are various patterns of defects, and depending on the defect image to be presented, it is difficult for the user to determine the degree of defect as a threshold, and an appropriate threshold cannot be set. There is a case.

  The present invention has been made in view of the above circumstances, and is used to determine a defect based on a comparison result in an image inspection by comparing an image obtained by reading an output result of an image formation output with a master image. It is an object of the present invention to set the threshold value more suitably than before.

  In order to solve the above problems, one aspect of the present invention is an image inspection apparatus that inspects a read image that is generated by reading an image formed and output on a recording medium based on an image to be imaged and output. Then, based on the image of the image formation output target, an inspection image generation unit that generates an inspection image for inspecting the read image, and a difference between the generated inspection image and the read image A difference degree determination unit that determines a difference degree that indicates a size of a pixel value that constitutes a difference image to be displayed, and a defect determination unit that determines a defect of the read image based on the determined difference degree and a threshold value of the difference degree Based on the difference image information stored in the storage medium, the difference image information storage processing unit that stores the difference image information that is information about the difference image for which the degree of difference is determined, on the storage medium A difference image selection unit that selects a predetermined number of the difference images from the difference images indicated by the difference image information stored in the image, and the selected difference images are classified according to the difference degree. A difference image presenting unit to be presented; and a threshold value setting unit configured to set the difference degree selected based on the presentation of the difference image as a threshold value of the difference degree.

  According to the present invention, in the inspection of an image by comparing the image obtained by reading the output result by the image formation output and the master image, the threshold value setting for determining the defect based on the comparison result is more preferable than the conventional one. It can be carried out.

It is a figure which illustrates the composition of the image inspection system containing the inspection device concerning the embodiment of the present invention. It is a block diagram which illustrates the hardware constitutions of the inspection apparatus which concerns on embodiment of this invention. It is a block diagram which illustrates functional composition of DFE, an engine controller, a print engine, and an inspection device concerning an embodiment of the present invention. It is a figure which illustrates the aspect of the comparison test | inspection which concerns on embodiment of this invention. 1 is a diagram illustrating a configuration of a print engine, an inspection apparatus, and a stacker according to an embodiment of the invention. It is a block diagram which illustrates the functional composition of the master image processing part concerning the embodiment of the present invention. It is a block diagram which illustrates the functional composition of the inspection control part concerning the embodiment of the present invention. It is a flowchart which illustrates the test | inspection operation | movement which concerns on embodiment of this invention. It is a figure which illustrates the level information stored in the level information storage part which concerns on embodiment of this invention. It is a figure which illustrates the threshold stored in the threshold storage part concerning an embodiment of the present invention. It is a figure which illustrates an example of difference image information stored in a difference image information storage part concerning an embodiment of the present invention. It is a flowchart which illustrates the operation | movement of the threshold value setting by the test | inspection control part which concerns on embodiment of this invention. It is a figure which illustrates the threshold difference level selection screen which concerns on embodiment of this invention. It is a figure which illustrates the difference image in the same difference level which concerns on embodiment of this invention. It is a figure which illustrates difference image information stored in a difference image information storage part concerning an embodiment of the present invention. It is a flowchart which illustrates the operation | movement of the threshold value setting by the test | inspection control part which concerns on embodiment of this invention. It is a figure which illustrates the threshold difference level selection screen which concerns on embodiment of this invention. It is a figure which illustrates the threshold difference level selection screen which concerns on embodiment of this invention. It is a figure which illustrates the threshold difference level selection screen which concerns on embodiment of this invention. It is a figure which illustrates the threshold difference level selection screen which concerns on embodiment of this invention. It is a figure which illustrates the threshold difference level selection screen which concerns on embodiment of this invention. It is a figure which illustrates the selection reference | standard change screen which concerns on embodiment of this invention. It is a figure which illustrates the threshold difference level selection screen which concerns on embodiment of this invention.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the present embodiment, an image inspection system including an inspection apparatus that inspects an output result by comparing a read image obtained by reading an output result by image formation output with a master image will be described. In particular, in the present embodiment, the processing for setting the threshold value for determining the image defect based on the comparison result in accordance with the inspection accuracy intended by the user in the image inspection system will be described as a feature. . FIG. 1 is a diagram illustrating an overall configuration of an image inspection system according to the present embodiment.

  As shown in FIG. 1, the image inspection system according to the present embodiment includes a DFE (Digital Front End) 1, an engine controller 2, a print engine 3, an inspection device 4, and an interface terminal 5. The DFE 1 is an image processing apparatus that generates image data to be printed based on a received print job, that is, bitmap data that is an output target image, and outputs the generated bitmap data to the engine controller 2.

  The engine controller 2 controls the print engine 3 based on the bitmap data received from the DFE 1 to execute image formation output. Further, the engine controller 2 uses the bitmap data received from the DFE 1 as information serving as a basis of an inspection image to be referred to when the inspection device 4 inspects the result of image formation output by the print engine 3. Send to.

  The print engine 3 is an image forming apparatus that executes image formation output on a sheet as a recording medium based on bitmap data in accordance with control of the engine controller 2. As the recording medium, in addition to the above-described paper, a sheet-like material such as a film or plastic can be used as long as it is an object for image formation output.

  The inspection device 4 generates a master image based on the bitmap data input from the engine controller 2. The inspection device 4 is an image inspection device that inspects an output result by comparing a read image generated by reading a sheet output from the print engine 3 with a reading device with the generated master image.

  When the inspection device 4 determines that the output result is defective, the inspection device 4 notifies the engine controller 2 of information indicating the page determined as defective. Thereby, reprint control of the defective page is executed by the engine controller 2.

  The interface terminal 5 is an information processing terminal for displaying a GUI (Graphical User Interface) for confirming a defect determination result by the inspection apparatus 4 and a GUI for setting parameters in the inspection. For example, the interface terminal 5 is realized by a general information processing terminal such as a PC (Personal Computer).

  Here, hardware constituting the DFE 1, the engine controller 2, the print engine 3, the inspection apparatus 4, and the interface terminal 5 according to the present embodiment will be described with reference to FIG. FIG. 2 is a block diagram illustrating a hardware configuration of the inspection apparatus 4 according to the present embodiment. In FIG. 2, the hardware configuration of the inspection apparatus 4 is shown, but the same applies to other apparatuses.

  As shown in FIG. 2, the inspection apparatus 4 according to the present embodiment has the same configuration as an information processing apparatus such as a general PC (Personal Computer) or a server. That is, the inspection apparatus 4 according to the present embodiment includes a CPU (Central Processing Unit) 10, a RAM (Random Access Memory) 20, a ROM (Read Only Memory) 30, an HDD (Hard Disk Drive) 40, and an I / F 50. Connected through. Further, an LCD (Liquid Crystal Display) 60, an operation unit 70, and a dedicated device 80 are connected to the I / F 50.

  The CPU 10 is a calculation means and controls the operation of the entire inspection apparatus 4. The RAM 20 is a volatile storage medium capable of reading and writing information at high speed, and is used as a work area when the CPU 10 processes information. The ROM 30 is a read-only nonvolatile storage medium and stores a program such as firmware. The HDD 40 is a non-volatile storage medium that can read and write information, and stores an OS (Operating System), various control programs, application programs, and the like.

  The I / F 50 connects and controls the bus 90 and various hardware and networks. The LCD 60 is a visual user interface for the user to check the state of the inspection apparatus 4. The operation unit 70 is a user interface such as a keyboard and a mouse for the user to input information to the inspection apparatus 4.

  The dedicated device 80 is hardware for realizing a dedicated function in the engine controller 2, the print engine 3, and the inspection apparatus 4. In the case of the print engine 3, the dedicated device 80 is a transport mechanism that transports a sheet of image formation output target, or a plotter device that executes image formation output on a paper surface. Further, the engine controller 2 and the inspection device 4 are dedicated arithmetic devices for performing image processing at high speed. Such an arithmetic unit is configured as an ASIC (Application Specific Integrated Circuit), for example. A reading device that reads an image output on a paper surface is also realized by the dedicated device 80.

  In such a hardware configuration, the software control unit is configured by the CPU 10 performing calculations in accordance with a program stored in the ROM 30 or a program read to the RAM 20 from a recording medium such as the HDD 40 or an optical disk (not shown). The A functional block that realizes the functions of the DFE 1, the engine controller 2, the print engine 3, the inspection device 4, and the interface terminal 5 according to the present embodiment is configured by a combination of the software control unit configured as described above and hardware. Is done.

  FIG. 3 is a block diagram illustrating functional configurations of the DFE 1, the engine controller 2, the print engine 3, and the inspection device 4 according to the present embodiment. In FIG. 3, data transmission / reception is indicated by a solid line, and the flow of paper is indicated by a broken line. As illustrated in FIG. 3, the DFE 1 according to the present embodiment includes a job information processing unit 101 and a RIP processing unit 102. The engine controller 2 includes a data acquisition unit 201, an engine control unit 202, and a bitmap transmission unit 203. The print engine 3 includes an image forming unit 301. The inspection device 4 includes a reading device 400, a read image acquisition unit 401, a master image processing unit 402, an inspection control unit 403, and a comparative inspection unit 404.

  The job information processing unit 101 executes image formation output based on a print job input from outside the DFE 1 via a network or a print job generated based on image data stored in the DFE 1 by an operator's operation. Control. When executing the image formation output, the job information processing unit 101 causes the RIP processing unit 102 to generate bitmap data based on the image data included in the print job.

  The RIP processing unit 102 generates bitmap data for the print engine 3 to execute image formation output based on the image data included in the print job, under the control of the job information processing unit 101. Bitmap data is information of each pixel constituting an image to be imaged and output.

  The print engine 3 according to the present embodiment executes image formation output based on binary images of CMYK (Cyan, Magenta, Yellow, blackK). On the other hand, generally, image data included in a print job is a multi-valued image in which one pixel is expressed by multi-gradation such as 256 gradations. Therefore, the RIP processing unit 102 converts the image data included in the print job from a multi-valued image to a small-valued image, generates CMYK binary data for each color, and transmits it to the engine controller 2.

  The data acquisition unit 201 acquires bitmap data input from the DFE 1 and operates the engine control unit 202 and the bitmap transmission unit 203, respectively. The engine control unit 202 causes the print engine 3 to execute image formation output based on the bitmap data transferred from the data acquisition unit 201. The bitmap transmission unit 203 transmits the bitmap data acquired by the data acquisition unit 201 to the inspection apparatus 4 for generating a master image.

  The image forming unit 301 acquires bitmap data input from the engine controller 2, executes image formation output on the printing paper, and outputs printed paper. The image forming unit 301 according to the present embodiment is realized by a general electrophotographic image forming mechanism, but other image forming mechanisms such as an ink jet method can also be used.

  The reading device 400 is an image reading unit that reads an image formed on a sheet of printing paper output by printing performed by the image forming unit 301 and outputs a read image. The reading device 400 is, for example, a line scanner installed on a conveyance path inside the inspection device 4 for printing paper output by the image forming unit 301. The reading device 4 reads an image formed on the paper surface by scanning the paper surface of the conveyed printing paper, and outputs the generated read image.

  The read image generated by the reading device 400 is an inspection target by the inspection device 4. The read image is an image generated by reading the paper surface of the paper output by the image forming output. The read image acquisition unit 401 acquires a read image generated by reading the paper surface of the printing paper by the reading device 400. The read image acquired by the read image acquisition unit 401 is input to the comparison inspection unit 404 for comparison inspection. Note that the input of the read image to the comparison inspection unit 404 is executed under the control of the inspection control unit 403. At that time, the inspection control unit 403 obtains the read image and inputs it to the comparison inspection unit 404.

  The master image processing unit 402 acquires the bitmap data input from the engine controller 2 as described above, and generates a master image that is an inspection image for comparison with the inspection target image. That is, the master image processing unit 402 functions as an inspection image generation unit that generates a master image, which is an inspection image for performing an inspection of a read image, based on an image that is an image formation output target. The master image generation processing by the master image processing unit 402 will be described in detail later.

  The inspection control unit 403 is a control unit that controls the operation of the entire inspection apparatus 4, and each component included in the inspection apparatus 4 operates according to the control of the inspection control unit 403. The comparison inspection unit 404 performs a comparison inspection between the read image input from the read image acquisition unit 401 and the master image generated by the master image processing unit 402. The comparison inspection unit 404 is configured by the ASIC described above in order to quickly process a huge amount of calculation.

  Specifically, as described above, the comparison inspection unit 404 compares the 200 dpi read image and the master image expressed in 8 bits for each RGB color for each corresponding pixel, and the above described 8 bits for each RGB color pixel for each pixel. The difference value between the values is calculated. Based on the absolute value of the difference value thus calculated (hereinafter simply referred to as “difference”), the inspection control unit 403 performs an inspection for determining a defect in the read image.

  When comparing the read image and the master image, the comparison inspection unit 404 superimposes the master image divided for each predetermined range on the read image corresponding to the divided range, as shown in FIG. The pixel value of the pixel, that is, the density difference is calculated. Such processing is realized by the inspection control unit 403 acquiring images in the overlapping range from the master image and the read image and inputting them to the comparison inspection unit 404.

  Further, the inspection control unit 403 determines the position where the total value of the calculated difference values is the smallest as an accurate overlay position while shifting the range of the image acquired from the read image vertically and horizontally. The calculated difference value of each pixel is adopted as a comparison result. Therefore, the comparison inspection unit 404 can output the vertical and horizontal shift amounts when determined as the overlay position together with the difference value of each pixel.

  As shown in FIG. 4, each square divided on the grid is a predetermined range in which the difference values of the pixels described above are summed. In addition, the size of each division range illustrated in FIG. 4 is determined based on a range in which the comparison / inspection unit 404 configured by the ASIC can compare pixel values at a time as described above, for example.

  By such processing, the difference value is calculated after the read image and the master image are aligned. By comparing the difference value calculated in this way with a predetermined threshold value, a defect in the image is determined. Further, for example, even if there is a difference in scale between the entire read image and the entire master image, the influence of the scale is reduced by dividing and positioning for each range as shown in FIG. Is possible.

  Further, in each of the divided ranges as shown in FIG. 4, it is predicted that the amount of positional deviation between adjacent ranges is relatively close. Therefore, when performing the comparative inspection for each of the divided ranges, the above-described calculation is performed while shifting in the vertical and horizontal directions with the positional deviation amount determined by the comparative inspection of the adjacent regions as the center. As a result, even if the number of calculations is reduced while shifting vertically and horizontally, there is a high possibility that the calculation based on the correct overlay position will be executed, and the calculation amount as a whole can be reduced.

  Next, the mechanical configuration of the print engine 3, the inspection device 4, and the stacker 6 and the sheet conveyance path will be described with reference to FIG. As shown in FIG. 5, in the image forming unit 301 included in the print engine 3 according to the present embodiment, the photosensitive drums 12Y, 12M, 12C, and 12K of each color are arranged along the conveyance belt 11 that is an endless moving unit. This is a so-called tandem type. That is, along the transport belt 11 that is an intermediate transfer belt on which an intermediate transfer image to be transferred to a sheet fed from the paper feed tray 13 is formed, in order from the upstream side in the transport direction of the transport belt 11. Photosensitive drums 12Y, 12M, 12C, and 12K are arranged. Hereinafter, the photosensitive drums 12Y, 12M, 12C, and 12K of the respective colors are collectively referred to as the photosensitive drum 12.

  Each color image developed with toner on the surface of the photosensitive drum 12 for each color is superimposed on the conveyor belt 11 and transferred to form a full color image. The full-color image formed on the transport belt 11 in this way has a sheet surface of the paper transported on the path by the function of the transfer roller 14 at a position closest to the paper transport path indicated by a broken line in the drawing. Transcribed above.

  The paper on which the image is formed on the paper surface is further conveyed, the image is fixed by the fixing roller 15, and then conveyed to the inspection device 4. In the case of double-sided printing, the sheet on which an image is formed and fixed on one side is conveyed to the reversing path 16 and is reversed and conveyed to the transfer position of the transfer roller 14 again.

  The reading device 400 is configured by an information processing device inside the inspection device 4 by reading each surface of the paper conveyed from the image forming unit 301 in the paper conveyance path inside the inspection device 4 and generating a read image. The image is output to the read image acquisition unit 401. Further, the sheet whose paper surface has been read by the reading device 400 is further conveyed inside the inspection device 4, conveyed to the stacker 6, and discharged to the paper discharge tray 601. 5 shows an example in which the reading device 400 is provided only on one side of the paper in the paper transport path in the inspection device 4, but in order to enable inspection of both sides of the paper, The reading device 400 may be arranged on each of both sides.

  Next, a functional configuration of the master image processing unit 402 according to the present embodiment will be described. FIG. 6 is a block diagram illustrating an internal configuration of the master image processing unit 402. As illustrated in FIG. 6, the master image processing unit 402 includes a small-value / multi-value conversion processing unit 421, a resolution conversion processing unit 422, a color conversion processing unit 423, and an image output processing unit 424. Note that the master image processing unit 402 according to the present embodiment is realized by operating the dedicated device 80 described in FIG. 2, that is, hardware configured as an ASIC, according to software control.

  The low-value / multi-value conversion processing unit 421 generates a multi-value image by performing low-value / multi-value conversion processing on a binary image expressed in colored / colorless. The bitmap data according to the present embodiment is information to be input to the print engine 3, and the print engine executes image formation output based on CMYK (Cyan, Magenta, Yellow, blackK) color binary images. On the other hand, the read image, which is the image to be inspected, is a multi-valued image of RGB (Red, Green, Blue), which is the basic three primary colors, and is a multi-valued image. The image is converted into a multi-valued image. As the multivalued image, for example, an image expressed by 8 bits for each of CMYK can be used.

  The small value / multivalue conversion processing unit 421 performs an 8-bit extension process and a smoothing process as the small value / multivalue conversion process. The 8-bit extension process is a process of converting 0/1 data, which is 1 bit, into 8 bits, converting “0” to “0” and converting “1” to “255”. The smoothing process is a process of smoothing an image by applying a smoothing filter to 8-bit data.

  In this embodiment, the print engine 3 executes image formation output based on CMYK binary images, and the master image processing unit 402 includes a low-value multi-value conversion processing unit 421. Is an example. That is, when the print engine 3 executes image formation output based on a multi-value image, the low-value multi-value conversion processing unit 421 can be omitted.

  In addition, the print engine 3 may have a function of performing image formation output based on a low-value image such as 2 bits instead of 1 bit. In this case, it can be dealt with by changing the function of the 8-bit extension processing. That is, in the case of 2 bits, the gradation value is four values of 0, 1, 2, and 3. Therefore, in the case of 8-bit expansion, “0” is converted to “0”, “1” is converted to “85”, “2” is converted to “170”, and “3” is converted to “255”.

  The resolution conversion processing unit 422 performs resolution conversion so that the resolution of the multi-value image generated by the small-value multi-value conversion processing unit 421 matches the resolution of the read image that is the image to be inspected. In the present embodiment, since the reading device 400 generates a 200 dpi read image, the resolution conversion processing unit 422 converts the resolution of the multi-valued image generated by the small-value multi-value conversion processing unit 421 to 200 dpi.

  The color conversion processing unit 423 acquires an image whose resolution has been converted by the resolution conversion processing unit 422, and performs gradation conversion and color expression format conversion. The tone conversion process is a color tone conversion process for matching the color tone of the master image with the color tone of the image formed on the paper surface by the image forming unit 301 and the color tone of the image read and generated by the reading device 400. .

  The color representation format conversion process is a process for converting an image in the CMYK format into an image in the RGB format. As described above, since the read image according to this embodiment is an RGB format image, the color conversion processing unit 423 converts the CMYK format image that has been subjected to the gradation conversion processing into an RGB format. As a result, a 200 dpi multi-valued image expressed by 8 bits (total 24 bits) of each RGB color is generated for each pixel.

  The image output processing unit 424 outputs the master image generated by the processing up to the color conversion processing unit 423. As a result, the inspection control unit 403 acquires a master image from the master image processing unit 402.

  Next, a functional configuration of the inspection control unit 403 according to the present embodiment will be described. FIG. 7 is a block diagram illustrating a functional configuration of the inspection control unit 403 according to this embodiment. As shown in FIG. 7, the inspection control unit 403 according to the present embodiment includes an information input unit 431, a level determination unit 432, a level information storage unit 433, a defect determination unit 434, a threshold storage unit 435, and a difference image information storage processing unit. 436, a difference image information storage unit 437, a difference image selection unit 438, a difference image presentation unit 439, a threshold setting unit 440, and a controller communication unit 441.

  FIG. 8 is a flowchart illustrating the operation of defect inspection by the inspection control unit 403 according to this embodiment. FIG. 12 is a flowchart illustrating an example of threshold setting operation used in defect inspection by the inspection control unit 403 according to this embodiment. Hereinafter, first, the operation of defect inspection by the inspection control unit 403 according to the present embodiment will be described with reference to FIG. 8, and the operation of threshold setting will be described with reference to FIG.

  In the inspection control unit 403 according to the present embodiment, as illustrated in FIG. 8, first, the information input unit 431 acquires a master image from the master image processing unit 402 (S800), and acquires a read image from the read image acquisition unit 401. Obtain (S801). Note that the process of S800 and the process of S801 are not limited in context, and may be executed in the reverse order or may be executed in parallel.

  As described with reference to FIG. 4, the information input unit 431 that has acquired the master image and the read image extracts a predetermined range of images from the master image and the read image and inputs the images to the comparison inspection unit 404, thereby comparing the inspection unit. In 404, an image comparison inspection is executed. The comparison inspection unit 404 calculates a difference value between each pixel constituting the read image and each pixel constituting the master image as an execution result of the comparison inspection, and outputs the difference value to the level determination unit 432.

  The level determination unit 432 to which the difference value is input by the comparison inspection unit 404 acquires a difference image composed of the input difference value (S803). The level determination unit 432 that has acquired the difference image determines the difference level of the acquired difference image based on the level information stored in the level information storage unit 433, and uses the determined difference level as the defect determination unit 434. (S804).

  FIG. 9 is a diagram illustrating level information stored in the level information storage unit 433. As shown in FIG. 9, the level information is a table in which “difference level” and “difference value” indicating the upper limit of the range of each “difference level” are associated with each other. The “difference level” is a difference degree indicating the size of a pixel value constituting a difference image. In the present embodiment, the larger the “difference level” value, the larger the associated “difference value” value is. And

  That is, in this embodiment, the magnitude relationship of the “difference values” shown in FIG. 9 is P0 <P1 <P2 <P3 <P4 <P5. Note that P0 is a lower limit value of the difference value, and when the difference value is P0 or less, there is no difference between the read image and the master image. Further, P0 to P5 are determined in advance by an administrator of the image inspection apparatus. Further, the level information may be set for each cause of the difference (dirt, streak, etc.).

  In the processing of S804, the level determination unit 432 compares the total value (or average value) of the pixel values of each pixel of the difference image with the “difference value” value shown in FIG. Determine. For example, if the total value (or difference value) is greater than P0 and less than or equal to P1, the “difference level” is “level 1”. For example, when the total value (or difference value) is greater than P4 and less than or equal to P5, the “difference level” is “level 5”. That is, the level determination unit 432 functions as a difference level determination unit that determines the difference level of the difference image.

  The defect determination unit 434 to which the difference level is input from the level determination unit 432 determines whether or not the difference image acquired in the processing of S803 is a defect (S805). Specifically, the defect determination unit 434 determines that the difference image is defective when the input difference level is greater than or equal to the threshold of the difference level stored in the threshold storage unit 435.

  FIG. 10 is a diagram illustrating threshold values stored in the threshold storage unit 435. In the case shown in FIG. 10, the threshold is set to “level 3”. In this case, when the input difference level is “level 1”, the defect determination unit 434 determines that the difference image is not defective, and when the difference level is “level 3” or higher, the difference image is Judged as a defect. The process of suitably setting this threshold is one of the gist of the present embodiment, and details will be described later. Note that the threshold value stored in the threshold value storage unit 435 may be set for each cause of the difference.

  When the level determination process of S804 is completed, the difference image information storage processing unit 436 stores information on the difference image for which the level determination is performed by the level determination unit 432 (hereinafter referred to as “difference image information”) as a storage medium. Is stored in the difference image information storage unit 437 (S806). FIG. 11 is a diagram illustrating a list of difference image information stored in the difference image information storage unit 437. As shown in FIG. 11, in the difference image information, for example, “image ID”, “difference level”, “difference image”, “difference value”, “difference cause”, and “determination date” are associated.

  “Image ID” is information for identifying the difference image, “Difference level” is the difference level of the difference image determined by the level determination unit 432, and “Difference image” is determined by the level determination unit 432 This is information indicating the image file of the difference image and the storage location of the image file. The “difference value” is a pixel value of the difference image, the “difference cause” is a cause of occurrence of the difference (hereinafter referred to as “difference cause”), and the “determination date” is a level determination. Time information (for example, date and time) determined by the unit 432 for level determination.

  The cause of the difference is a streak or dirt, and is specified by, for example, a labeling process for the difference image. The labeling process is a process of assigning the same number (label) to pixels (connected components) in which the same color, the same region, or the like continues in the input image. By performing a labeling process on the difference image, the cause of the difference is specified from the feature amount such as the area and length of the connected component. For example, a feature amount is predetermined for each difference cause, and the difference cause determined for the feature amount closest to the feature amount of the connected component subjected to the labeling process is specified as the difference cause of the connected component. .

  The controller communication unit 441 executes engine control such as a reprint request based on the determination result by the defect determination unit 434 (S807). Such processing in the inspection control unit 403 is repeated until output of all pages is completed for one print job. When output and inspection of all pages is completed, the processing ends. Note that the processing in S805 and the processing in S806 are not limited in context, and may be executed in the reverse order or may be executed in parallel. In addition, the processing in S806 and the processing in S807 are not limited in context, so if the processing in S805 is performed before the processing in S807, they may be executed in the reverse order or executed in parallel. May be.

  Next, the threshold setting operation by the inspection control unit 403 according to the present embodiment will be described with reference to FIG. In the inspection control unit 403 according to the present embodiment, as shown in FIG. 12, first, the difference image selection unit 438 has the same “cause of difference” from the list of difference image information stored in the difference image information storage unit 437. Some difference image information is acquired (S1201). In the present embodiment, it is assumed that difference image information whose “difference cause” is “streak” is acquired.

  The difference image selection unit 438 that has acquired the difference image information having the same “difference cause” classifies the acquired difference image information for each level indicated by the “difference level” (S1202). The difference image selection unit 438 that classifies the difference image information for each level selects “difference images” included in each of a predetermined number (for example, four) of difference image information from the difference image information for each classified level. (S1203).

  Specifically, for example, in the processing of S1203, the difference image selection unit 438 causes the “difference image” included in each of the difference image information having the largest “difference value” and the difference image information having the smallest “difference value”. Select. Further, the difference image selection unit 438 selects the “difference image” included in each difference image information closest to the equal interval between the difference value having the smallest “difference value” and the largest difference value.

  The difference image selected in the processing of S1203 is a presentation image presented on the display unit or the like of the interface terminal 5 in order for the user to set a threshold value. The difference image selection unit 438 repeats the process of S1203 (S1204 / NO) until the difference image selection process is completed at all classified levels (S1204 / YES).

  When the difference image selection processing at all levels by the difference image selection unit 438 is completed, the difference image presentation unit 439 displays the threshold difference level selection screen including the difference image selected by the difference image selection unit 438 as the display unit of the interface terminal 5. (S1205). FIG. 13 is a diagram illustrating a threshold difference level selection screen displayed on the display unit of the interface terminal 5.

  As shown in FIG. 13, on the threshold difference level selection screen, a predetermined number (for example, four) of difference images selected by the difference image selection unit 438 and whose cause of difference is a streak are displayed side by side for each difference level. The Also, on the threshold difference level selection screen, the difference images are displayed side by side in the order from the smallest “difference value” at the same difference level. Further, under each difference image, a value of “image ID” associated with the difference image is displayed.

  The threshold difference level selection screen also includes a radio button for selecting a difference level as a threshold, a “decision” button for determining the selected difference level as a threshold, and a “cancel” button for canceling the threshold difference level selection process. Etc. are provided. In the present embodiment, the case of displaying the difference images of all the difference levels has been described as an example. However, the difference level for displaying the difference image may be limited according to the user setting or the like. Alternatively, the display number of difference images for each difference level may be changed.

  As shown in FIG. 13, the higher the difference level, the thicker and more noticeable the streaks that are the cause of the difference. FIG. 14 is a diagram illustrating a difference image at the same difference level. In FIG. 14, for the sake of clarity of explanation, the difference in the thickness of the streaks is illustrated more easily than in the case shown in FIG. As shown in FIG. 14, at the same difference level, for example, the difference images are arranged in the order of “difference value” from the left side, and the difference image on the right side becomes thicker and more noticeable.

  When the user views the difference images arranged for each difference level on the threshold difference level selection screen shown in FIG. 13, selects the minimum difference level recognized as a defect, and presses the “decision” button, the threshold setting unit 440 Acquires information of the selected difference level (S1206). The threshold setting unit 440 stores the acquired difference level in the threshold storage unit 435 and sets it as a threshold (S1207).

  As described above, the image inspection apparatus according to the present embodiment presents the user with the difference image selected based on the difference image information for which the difference level is determined for the actual printed matter. Thereby, since the user can determine the difference level recognized as a defect by comparing the difference image presented based on a certain tendency, the image inspection apparatus determines the defect based on the comparison result. The threshold value can be set more suitably than in the past.

  In the above-described embodiment, the inspection control unit 403 has been described as an example in which the difference image to be presented to the user is selected based on the difference cause and the difference value included in the difference image information. In addition, the examination control unit 403 may select a difference image to be presented to the user based on the difference cause and the determination date. In this case, in the processing of S1203 illustrated in FIG. 12, the differential image selection unit 438 selects, for example, differential images included in each of the predetermined number of differential image information in order of “decision date” illustrated in FIG. With such a configuration, the user can compare the difference images whose difference levels have been determined most recently, so that the image inspection apparatus can set a more suitable threshold according to the current inspection state.

  Moreover, in the said embodiment, the structure by which a difference image is selected based on a difference value or a determination date is not essential, Even if the difference image information selected at random from the difference image information of the same difference cause is used Good. Further, the selection based on the difference value is not limited to the aspect described in the above embodiment, and the difference image selection unit 438 may select a predetermined number of difference images in descending order of the difference value, or in ascending order of the difference value. A predetermined number of difference images may be selected.

  In addition, the inspection control unit 403 may select a difference image to be presented to the user based on the type of the area of the difference image. FIG. 15 is a diagram exemplifying difference image information stored in the difference image information storage unit 437 according to an embodiment that selects a difference image to be presented to the user based on the type of the area of the difference image. As shown in FIG. 15, the difference image information includes “area type” indicating the area type of the difference image in addition to the information shown in FIG. 11.

  The “area type” is, for example, “paper white” in which toner or ink is not output in the print area, “picture” in which a picture is output, “background” such as a solid area, and “edge” that is an edge area. The “region type” is determined based on the state of the determination target region of the master image input from the information input unit 431 when the level determination unit 432 determines the difference level, for example. Specifically, for example, when toner or ink is not output to the determination target area of the master image, the “area type” is determined as “paper white”.

  Further, the “area type” other than “paper white” is determined based on the flatness of the determination target area of the master image, for example. For example, when the flatness is “0”, the “region type” is “edge” with the largest change in image value. For example, when the flatness is between “1” and “6”, the “region type” is “picture” whose image value change is smaller than “edge”. For example, when the flatness is “7”, the “region type” is “background” with the smallest change in image value.

  FIG. 16 is a flowchart illustrating the threshold setting operation by the inspection control unit 403 according to the embodiment that selects a difference image based on “region type”. As illustrated in FIG. 16, the difference image selection unit 438 acquires difference image information having the same “difference cause” and “region type” from the list of difference image information stored in the difference image information storage unit 437. (S1601). In the present embodiment, it is assumed that difference image information in which “cause of difference” is “streak” and “area type” is “background” is acquired.

  The difference image selection unit 438 that has acquired the difference image information having the same “difference cause” and “region type” indicates the acquired difference image information by the “difference level” as in the processing of S1202 illustrated in FIG. Classification is performed for each level (S1602). Thereafter, the difference image selection unit 438 performs the same processing as S1203 to S1207 shown in FIG. 12 in the processing of S1603 to S1607.

  Note that, in the present embodiment, the difference image selection unit 438 is described as an example in which the same processing as the processing of S1203 illustrated in FIG. 12 is performed in the processing of S1603. In addition, for example, when the “region type” is “background”, the difference image selection unit 438 determines a predetermined number of difference images based on the background density (maximum value, minimum value, large order, small order, etc.). May be selected.

  FIG. 17 is a diagram illustrating a threshold difference level selection screen displayed on the display unit of the interface terminal 5 in the process of S1605. As shown in FIG. 17, on the threshold difference level selection screen, the difference cause selected by the difference image selection unit 438 is a streak, and a predetermined number (for example, four) of difference images that are background areas are difference levels. They are displayed side by side.

  As shown in FIG. 17, streaks are generated in the difference image that is the background area of various densities (indicated by various hatchings in FIG. 17), so that the lines are easily noticeable even at the same difference level. May be different.

  Also, FIG. 18 shows the threshold difference level selection in the case where the difference image information in which the “difference cause” is “streaks” and the “region type” is “picture” in the processing of S1601 shown in FIG. It is a figure which illustrates a screen. As shown in FIG. 18, in the threshold difference level selection screen, the difference image selected by the difference image selection unit 438 is a difference cause, and a predetermined number (for example, four) of difference images that are design areas are difference levels. They are displayed side by side. In the case shown in FIG. 18, the same pattern area is included, but these patterns are merely examples, and all may be different patterns.

  In the present embodiment, as in the process of S1203 illustrated in FIG. 12, the difference image selection unit 438 is described as an example in which a difference image selected based on the difference value is displayed. In addition, for example, when the “region type” is “picture”, the difference image selection unit 438 determines a predetermined number of difference images based on flatness (maximum value, minimum value, large order, small order, etc.). May be displayed.

  As shown in FIG. 18, streaks are generated in the differential images that are areas of various patterns, and therefore, the noticeability of the streaks may be different even at the same differential level. With the configuration in which the presentation image is selected based on such “region type”, the user determines the difference level to be recognized as a defect by comparing difference images of various patterns with different visual impressions even at the same difference level. be able to. Also, with this configuration, the image inspection apparatus can set a threshold value so that the user can appropriately inspect defects in the type of region that the user particularly wants to pay attention to, so that the threshold value can be set more suitably than in the past. It becomes possible.

  Further, in the above-described embodiment, the difference image selection unit 438 has been described as an example in which the difference image to be presented is selected from the difference image information having the same “difference cause”. In addition, the difference image selection unit 438 may select a difference image included in difference image information having different “difference causes” as a difference image to be presented. In this case, the difference image selection unit 438 acquires the difference image information having different “cause of difference” from the difference image information stored in the difference image information storage unit 437 for each difference level.

  For example, the difference image selection unit 438 selects a predetermined number (for example, one) of difference image information having different “difference causes” for each difference level. At that time, the difference image selection unit 438 may select the difference image information with the largest “difference value” from the difference image information with the same “difference cause”, or the difference image information with the latest “judgment date”. May be selected, or difference image information may be selected at random. Further, the difference image selection unit 438 may select different numbers of difference image information for each difference cause.

  FIG. 19 is a diagram illustrating a threshold difference level selection screen when difference image information with different “difference causes” is selected. As shown in FIG. 19, in the threshold difference level selection screen, difference images such as “streaks”, “dirt”, and “dots gathered” having different causes selected by the difference image selection unit 438 are displayed for each difference level. Are displayed side by side.

  Moreover, as shown in FIG. 19, the difference image of the same difference cause is displayed in the same position for every difference level. By such an aspect, it becomes easy for the user to compare difference images of the same difference cause of different difference levels, but such a configuration is not essential, and different difference cause difference images are displayed at the same position for each difference level. May be.

  In addition, in the threshold difference level selection screen shown in FIG. 19, a check for selecting an image ID associated with the difference image so that the user can select the minimum difference level recognized as a defect for each displayed difference image. A box may be provided. In this case, the threshold setting unit 440 can set a difference level threshold for each difference cause of the selected difference image. For example, in the case shown in FIG. 19, “level 1” is selected for the cause of the difference in the stain, but “level 2” is selected for the cause of the difference in the dot-like collection.

  As shown in FIG. 19, since difference images of various differences are displayed, the difference noticeability may be different even at the same difference level. With such a configuration in which a difference image with a different cause is selected as a presentation image, the user compares difference images with various visual impressions even at the same difference level to determine a difference level to be recognized as a defect. be able to. Therefore, the image inspection apparatus can more suitably set the threshold value for determining the defect based on the comparison result than before.

  In addition, the examination control unit 403 may select a difference image having a different “region type” as a presentation image. In this case, the difference image selection unit 438 acquires difference image information with different “region type” for each difference level from the difference image information stored in the difference image information storage unit 437.

  FIG. 20 is a diagram illustrating a threshold difference level selection screen when a difference image having a different “region type” is selected. As shown in FIG. 20, in the threshold difference level selection screen, difference images such as “paper white”, “background”, and “picture” having different region types selected by the difference image selection unit 438 are arranged for each difference level. Is displayed. Note that the number of difference images of “paper white”, “background”, and “picture” is not limited to this.

  Further, in the threshold difference level selection screen shown in FIG. 20, as in the case shown in FIG. 19, the minimum difference level that is recognized as a defect can be selected for each displayed difference image so that it is associated with the difference image. A check box for selecting the given image ID may be provided. In this case, the threshold setting unit 440 can set a difference level threshold for each region type of the selected difference image. For example, in the case shown in FIG. 20, “level 1” is selected for the difference image on the pattern area, but “level 2” is selected for the difference image on paper white.

  Even with such a configuration, the user can determine a difference level that is recognized as a defect by comparing difference images of various patterns having different visual impressions even at the same difference level. Therefore, the image inspection apparatus can more suitably set the threshold value for determining the defect based on the comparison result than before.

  In addition, the inspection control unit 403 may select a difference image having a difference cause and a region type as a presentation image by combining the modes illustrated in FIGS. 19 and 20.

  In the threshold difference level selection screen according to the present embodiment, it may be possible to change the displayed difference image or change the reference of the difference image to be selected. FIG. 21 is a diagram illustrating a threshold difference level selection screen including a “redisplay” button for changing the displayed difference image and a “reference change” button for changing the reference of the selected difference image.

  As illustrated in FIG. 21, when the “redisplay” button is pressed by the user, the difference image selection unit 438 selects a threshold difference level selection screen from the difference image information stored in the difference image information storage unit 437. A difference image different from the difference image displayed in is selected again. Thereby, the difference image presentation unit 439 displays the difference image reselected by the difference image selection unit 438.

  With such a configuration, the user can compare the difference images that are easier to determine the difference level that is recognized as a defect. Therefore, the image inspection apparatus has conventionally set a threshold value for determining a defect based on the comparison result. It becomes possible to carry out more suitably. In such a configuration, when the difference image selection unit 438 next selects a presentation image, the difference image used when the user selects the difference level may be preferentially selected. Good. Accordingly, since a difference image that allows the user to more easily determine the difference level recognized as a defect can be preferentially displayed, the image inspection apparatus has conventionally set a threshold value for determining a defect based on the comparison result. It becomes possible to carry out more suitably.

  Also, as shown in FIG. 21, when the user presses the “Change Criteria” button, the difference image presentation unit 439 displays a screen for changing the selection criteria from the threshold difference level selection screen (hereinafter, “Choose Selection Criteria” The display changes to "screen"). FIG. 22 is a diagram illustrating a selection criterion change screen. As shown in FIG. 22, on the selection criterion change screen, each item of difference image information used as a reference when selecting a presentation image is selected.

  For example, as illustrated in FIG. 22, when the user selects “order of difference value” and “background” of the region type and presses the “change” button, the difference image selection unit 438 displays “region type”. Difference image information is acquired from the difference image information of “background” in the order of the difference values as shown in FIG. With such a configuration, it is possible to change the image presented according to the pattern of the difference image that the user wants to compare. Note that only one of the “redisplay” button and the “change reference” button shown in FIG. 21 may be provided.

  In the above embodiment, the difference image selection unit 438 selects a difference image included in each of a predetermined number of pieces of difference image information from the difference image information stored in the difference image information storage unit 437. As explained. However, for example, when the number of pieces of difference image information stored in the difference image information storage unit 437 is not sufficient and a predetermined number of pieces of difference image information cannot be acquired, the difference image selection unit 438 is a pseudo difference image. You may make it supplement the missing number. According to such a configuration, a pseudo difference image is temporarily displayed. However, as the difference image information is accumulated in the difference image information storage unit 437, the pseudo difference image is actually displayed. It is replaced with the difference image acquired from the printed matter.

  Moreover, in the said embodiment, the case where the difference image selected by the difference image selection part 438 was displayed on the display part etc. of the interface terminal 5 was demonstrated as an example. In addition, the difference images selected by the difference image selection unit 438 may be arranged for each difference level as shown in FIG.

  FIG. 23 is a diagram illustrating a threshold difference level selection screen when the selected difference image is formed and output. As shown in FIG. 23, the difference image is not displayed on the threshold difference level selection screen, and a radio button for selecting the difference level and other various buttons are provided. The user compares the difference images formed and output on the paper surface, and selects a difference level as a threshold value via the threshold difference level selection screen shown in FIG.

  With such a configuration, the user can determine the difference level that is recognized as a defect by comparing the actually printed difference image. Therefore, the image inspection apparatus uses the threshold value for determining the defect based on the comparison result. This setting can be performed more suitably than before. Even when the selected difference image is image-formed and output on the paper surface, a threshold difference level selection screen similar to that shown in FIG. 13 may be displayed on the display unit.

1 DFE
2 Engine Controller 3 Print Engine 4 Inspection Device 5 Interface Terminal 6 Stacker 10 CPU
20 RAM
30 ROM
40 HDD
50 I / F
60 LCD
70 Operation Unit 80 Dedicated Device 90 Bus 11 Conveyor Belt 12, 12Y, 10M, 12C, 12K Photosensitive Drum 13 Paper Tray 14 Transfer Roller 15 Fixing Roller 16 Reverse Pass 101 Job Information Processing Unit 102 RIP Processing Unit 201 Data Acquisition Unit 202 Engine control unit 203 Bitmap transmission unit 301 Image forming unit 400 Reading device 401 Read image acquisition unit 402 Master image processing unit 403 Inspection control unit 404 Comparative inspection unit 601 Paper discharge tray 421 Low-value multi-value conversion processing unit 422 Resolution conversion processing unit 423 Color conversion processing unit 424 Image output processing unit 431 Information input unit 432 Level determination unit 433 Level information storage unit 434 Defect determination unit 435 Threshold storage unit 436 Difference image information storage processing unit 437 Difference image information storage unit 438 Difference image selection unit 43 Difference image presenting unit 440 threshold setting unit 441 controller communication unit

JP 2014-44712 A

Claims (9)

An image inspection apparatus for inspecting a read image generated by reading an image formed and output on a recording medium based on an image to be imaged and output;
An inspection image generating unit that generates an inspection image for inspecting the read image based on the image to be imaged and output;
A difference degree determination unit that determines a difference degree indicating a magnitude of a pixel value constituting a difference image indicating a difference between the generated image for inspection and the read image;
A defect determination unit that determines a defect of the read image based on the determined difference and a threshold of the difference;
A difference image information storage processing unit that stores, in a storage medium, difference image information that is information about the difference image for which the degree of difference is determined;
A difference image selection unit that selects a predetermined number of the difference images from the difference images indicated by the difference image information stored in the storage medium based on the difference image information stored in the storage medium. When,
A difference image presenting unit that classifies and presents the selected difference image for each degree of difference; and
An image inspection apparatus comprising: a threshold setting unit configured to set the difference selected based on the presentation of the difference image as a threshold of the difference. The difference image information includes a difference cause that is a cause of the difference of the difference image,
The image inspection apparatus according to claim 1, wherein the difference image selection unit selects the difference image based on the cause of the difference. The image inspection apparatus according to claim 2, wherein the difference image selection unit selects the difference images having the same difference cause. The difference image information includes a type of the area of the difference image,
The image inspection apparatus according to claim 1, wherein the difference image selection unit selects the difference image based on a type of the region. The image inspection apparatus according to claim 4, wherein the difference image selection unit selects the difference images having the same type of the region. The difference image information includes a difference between the inspection image and the read image,
The image inspection apparatus according to claim 1, wherein the difference image selection unit selects the difference image based on the difference. The difference image information includes time information when the difference degree is determined,
The image inspection apparatus according to claim 1, wherein the difference image selection unit selects the difference image based on the time information. An image inspection system for inspecting a read image generated by reading an image formed and output on a recording medium based on an image to be imaged and output;
An image forming unit that performs image forming output on the recording medium;
An image reading unit that reads the image formed and output on the recording medium and generates the read image;
A read image acquisition unit for acquiring the generated read image;
An inspection image generating unit that generates an inspection image for inspecting the read image based on the image to be imaged and output;
A difference degree determination unit that determines a difference degree indicating a magnitude of a pixel value constituting a difference image indicating a difference between the generated image for inspection and the read image;
A defect determination unit that determines a defect of the read image based on the determined difference and a threshold of the difference;
A difference image information storage processing unit that stores, in a storage medium, difference image information that is information about the difference image for which the degree of difference has been determined;
A difference image selection unit that selects a predetermined number of the difference images from the difference images indicated by the difference image information stored in the storage medium based on the difference image information stored in the storage medium. When,
A difference image presenting unit that classifies and presents the selected difference image for each degree of difference; and
A threshold setting unit configured to set the difference selected based on the presentation of the difference image as a threshold of the difference. An image inspection method for inspecting a read image generated by reading an image formed and output on a recording medium based on an image of an image formation output target,
Based on the image of the image formation output target, generating an inspection image for inspecting the read image,
Determining a difference degree indicating a size of a pixel value constituting a difference image indicating a difference between the generated image for inspection and the read image;
Determining the defect of the read image based on the determined difference and the threshold of the difference,
Storing difference image information, which is information related to the difference image for which the degree of difference is determined, in a storage medium;
Based on the difference image information stored in the storage medium, a predetermined number of the difference images are selected from the difference images indicated by the difference image information stored in the storage medium,
The selected difference images are classified and presented for each degree of difference,
The image inspection method, wherein the difference degree selected based on the presentation of the difference image is set as a threshold value of the difference degree.