JP2013179511A - Inspection apparatus, inspection method, and program - Google Patents

Abstract

There is provided an inspection apparatus that prevents a correction image from becoming a difference image when comparing image data and preventing an erroneous determination of inspection.
Means for obtaining a read image by reading a printed matter printed in a printing device based on an image after image processing, and image processing having characteristics opposite to those of the image processing for the image after image processing And a means for obtaining an image before the image processing as a reference image, and a means for determining the quality of the printed matter by comparing the reference image with the read image. Inspection equipment.
[Selection] Figure 15

Description

  The present invention relates to a technique for inspecting the quality of a printed matter printed by a printing apparatus.

  There is a printing apparatus that determines whether a printed product is good or bad inline and inspects it (see Patent Document 1). The apparatus of Patent Document 1 performs PIP (Page Description Language) data input from a host computer, and RIP (Raster Image Processor) processing to develop it into RIP data (bitmap image) (RIP development). Then, the RIP data is printed by the printing unit to obtain a printed matter. Further, the printing apparatus obtains scan data (scanned image) by reading a printed matter with a scanner. Then, the printing apparatus determines the quality of the printed matter by comparing the RIP data and the scan data.

JP2007-50546 JP2007-300551 JP 2009-198727 A

  In general, RIP data that has undergone RIP processing is subjected to additional processing by an image processing unit included in the printing apparatus. For example, when the printing apparatus is set to print page number, stamp, or copy-forgery-inhibited pattern images, the image processing unit performs a process of combining these images with the RIP data. In the image processing unit, various image processing is performed on the RIP data. For example, if the printing apparatus is of an electrophotographic system, digital registration processing (see Patent Document 2) that cancels distortion of the exposure scanning line due to the mounting accuracy of the printing unit is performed. Alternatively, RIP data thinning processing (see Patent Document 3) for suppressing developer explosion in the developer fixing processing in the printing unit is performed.

  That is, the content of the RIP data image that has undergone RIP development is different from the content of the data image printed in the printing unit. For this reason, in the printing apparatus of Patent Document 1 that compares RIP data obtained by RIP-developing PDL data and scan data, there is a possibility of erroneous determination in determining whether a printed product is good or bad. The present invention solves this problem.

  The inspection apparatus according to the present invention includes a means for obtaining a read image by reading a printed matter printed on a printing apparatus based on an image after image processing, and the characteristics of the image processing are opposite to those of the image after image processing. A means for obtaining the image before the image processing as a reference image by performing the image processing, and a means for judging the quality of the printed matter by comparing the reference image with the read image. Features.

  According to the present invention, it is possible to determine the quality of a printed matter in consideration of various types of image processing applied to RIP data after RIP development.

Inspection system block diagram Inspection system configuration diagram Image processing unit Example of fixing tail image Fixing tail correction processing diagram Trailing correction processing flowchart in the printing apparatus unit Image example of tilt during image formation Digital registration processing diagram Digital registration processing flowchart in the printing apparatus section Printed document reading section Reference image data before reverse correction processing Scanned image data for inspection Reverse correction processing diagram of fixing tail correction processing Reverse correction process flowchart of the tailing correction process in the inspection control unit Reverse correction processing diagram of digital registration processing Reverse correction processing flowchart of digital registration processing in inspection control unit Verification method illustration Flow chart of image matching algorithm Print inspection processing flowchart in embodiment 1 Print inspection processing flowchart of inspection control unit in embodiment 2 Printing inspection process flowchart of the printing apparatus unit in the second embodiment

  Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram illustrating a configuration example of a real-time inspection (in-line inspection) system synchronized with printing according to the present embodiment. The in-line inspection system 1 (hereinafter referred to as “inspection system 1”) includes a printing device unit 10, an inspection device unit 20, and a finisher unit 800. The inspection device unit 20 includes a print document reading unit 500, an inspection control unit 600, and a print document discharge control unit 700. The printing apparatus unit 10 is connected to the print document reading unit 500 and the inspection control unit 600. The print document reading unit 500 is connected to the inspection control unit 600 and the print document discharge control unit 700. The print document discharge control unit 700 is connected to the finisher unit 800.

  FIG. 2 shows a hardware configuration diagram of the inspection system 1 according to the present embodiment, and a general-purpose PC 2 and a network 3 that are connected. The block numbers shown in FIG. 2 correspond to the processing unit numbers shown in FIG.

  The printing apparatus unit 10 includes an image reading unit 100, a printing apparatus operation unit 200, a printer unit 300, and a printing apparatus control unit 400. The printing apparatus control unit 400 is connected to the printing apparatus operation unit 200 and the printer unit 300 and controls them. The printing apparatus control unit 400 includes a CPU, a ROM, a RAM, and an HDD (storage unit) (not shown), and executes each process by linking these. The printing apparatus operation unit 200 is a user interface for the printing apparatus control unit 400. The printer unit 300 prints the image data received from the printing apparatus control unit 400 on a print medium (hereinafter referred to as “sheet”). The printing apparatus unit 10 executes the processing from S100 to S107 in FIG.

  Here, the operation of the printer unit 300 will be described. The printer unit 300 includes an exposure unit, a photosensitive drum, a development unit, a transfer unit, and a fixing unit. The printer unit 300 forms an electrostatic latent image on the photosensitive drum by irradiating the photosensitive drum with laser light having an intensity corresponding to the received image data. Subsequently, the printer unit 300 develops the electrostatic latent image on the photosensitive drum 302 by the developing unit to form a developer image, and transfers the developer image to the sheet by the transfer unit. The printer unit 300 fixes the transferred developer image on the sheet by the fixing unit.

  As described above, the inspection apparatus unit 20 includes the print document reading unit 500, the inspection control unit 600, and the print document discharge control unit 700. The inspection control unit 600 controls each processing unit. Further, the inspection control unit 600 and the print document discharge control unit 700 have a CPU, ROM, RAM, and HDD (storage means) (not shown), and execute these processes by linking these. The inspection device unit 20 executes the processing from S108 to S124 in FIG.

  The finisher unit 800 performs stapling processing and bookbinding processing as necessary on the printed material sent to the finisher unit 800, and discharges the printed material to a paper discharge tray so that the printed material can be distinguished according to the inspection result of the printed material. The finisher unit 800 discharges the printed matter to the acceptance tray if the inspection result of the printed matter is acceptable, and ejects the printed matter to the failure tray if the inspection result is unacceptable. The finisher unit 800 executes the process of S125 of FIG.

  Next, a processing flow from execution of a print job to inspection of printed matter and paper discharge of the inspection system 1 in this embodiment will be described with reference to FIG.

  First, the printing apparatus control unit 400 sets a print job and its inspection based on a user instruction via the printing apparatus operation unit 200 (S100). In this embodiment, the print job is described as a PDL print job for printing PDL data input from the PC 2 to the printing apparatus unit 10. The print job setting is also referred to as a print option setting. The print job setting includes the number of copies, color / monochrome, paper setting, single side / double side, resolution, layout, and the like. The inspection setting includes pass / fail threshold setting, paper discharge tray selection at the time of failure, and the like. The printing apparatus control unit 400 transmits the print job setting and the inspection setting to the inspection control unit 600 (S101).

  Next, the printing apparatus control unit 400 starts a print job, generates RIP data, and stores it in the HDD of the printing apparatus control unit 400 (S102). Then, the printing apparatus control unit 400 performs print option processing corresponding to the setting of the print job set in S100 on the generated RIP data (S103). The printing apparatus control unit 400 performs each correction process on the image data processed in S103 (S104). The processing of S103 and S104 will be described later in detail with reference to FIGS.

  Next, the printing apparatus control unit 400 transmits the image data (print image data) after each image processing in S104 to the inspection control unit 600 as the reference image data 1000 (see FIG. 11) of the inspection (S105). This reference image data is image data before being subjected to a later-described reverse correction process. Then, the printing apparatus control unit 400 transmits the print image data to the printer unit 300, and the printer unit 300 prints the print image data on the print medium (S106). The printer unit 300 discharges the print medium (printed material) on which the print image data is printed to the print document reading unit 500 (S107).

  The inspection control unit 600 receives the print job setting and the inspection setting transmitted by the printing apparatus control unit 400 in S101 (S113), and transmits the print original reading mode based on the information to the print original reading unit 500. (S114).

  The print original reading unit 500 receives the print original reading mode transmitted by the inspection control unit 600 in S114 (S108). Next, paper detection of the output printed matter 50 (FIG. 10) ejected from the printer unit 300 is performed (S109), and the image data of the print original (the inspection scan image data 1100 and the print original scan data are both detected by the line sensor 512). Read) (S110). The read image read, that is, the inspection scan image data 1100 is transmitted to the inspection control unit 600 (S111). That is, the printed document reading unit 500 functions as a read image acquisition unit. Thereafter, the output printed matter 50 is conveyed from the print original reading section 500 to the print original discharge control section 700 (S112).

  The inspection control unit 600 receives the reference image transmitted by the printing apparatus control unit 400 in S105 (S115), and receives the inspection scan image transmitted by the print document reading unit 500 in S111 (S116). Then, the inspection control unit 600 performs image processing with characteristics opposite to those of the image processing of S104 on the received reference image data 1000 (S117). This image processing will be described in detail later with reference to FIGS.

  Further, the inspection control unit 600 performs image collation / comparison such as descreen processing, resolution conversion processing, and color space conversion processing on the reference image data 1000 subjected to the reverse correction processing and the scan image data 1100 for inspection. Image pre-processing is performed for (S118). Then, the inspection control unit 600 compares and collates these two images (S119). This process will be described later in detail with reference to FIGS. The inspection control unit 600 transmits the inspection result based on the comparison processing and collation processing in S119 to the print document discharge control unit 700 (S120).

  The print document discharge control unit 700 receives the inspection result transmitted from the print document reading unit 500 in S120 (S121). For the output printed matter 50, the transport path is switched based on the received inspection result (S122). If the inspection result is acceptable, the output printed matter 50 is conveyed to a pass (S123).

  The finisher unit 800 discharges the output printed matter 50 conveyed from the print document discharge control unit 700 (S125).

  The processes in S103 and S104 in FIG. 19 will be described below. As illustrated in FIG. 3, the printing apparatus control unit 400 includes an image processing unit 430 including a print option processing unit 440 and a printer correction processing unit 450. The print option processing unit 440 performs the process of S103, and the printer correction processing unit 450 performs the process of S104.

  The print option processing unit 440 is a processing unit that performs page layout processing and tint block processing on RIP data, and includes a page layout processing unit 441 and a tint block processing unit 442. The page layout processing unit 441 performs a page composition process such as “Nin1 printing” (not shown), and the background pattern processing unit performs a process of adding background pattern information to a page image such as “printing prohibited” (not shown).

  The printer correction processing unit 450 includes a tail processing unit 451, a digital registration processing unit 452, and a transfer point storage unit 453. The tailing processing unit 451 performs processing (thinning-out processing) for suppressing fixing tailing in the fixing unit of the printer unit 300. The digital registration processing unit 452 performs processing (digital registration processing) for canceling the sub-scanning direction deviation of the laser light irradiated to the photosensitive drum by the exposure unit of the printer unit 300. Note that these digital registration processing and thinning-out processing are part of image processing for printing in the printer unit 300 in consideration of the device characteristics of the printer unit 300.

  Processing performed by the tailing processing unit 451 will be described with reference to FIGS. When an image fixing process is performed by the fixing unit 304 of the printer unit 300, fixing tailing is likely to occur in an image portion having specific characteristics. “Fixing tailing” is a phenomenon in which moisture contained in the recording material is heated by the fixing unit 304 and rapidly evaporated to partially blow off the developer on the paper before being fixed. Then, the blown-off developer is fixed at a place where the development enhancer should not adhere, and the image quality is deteriorated. An example of this fixing tailing is shown in FIG. The correction processing (also referred to as tailing processing or thinning-out processing) for suppressing the fixing tailing is the processing shown in FIG. In other words, before the image fixing process, the RIP data is thinned out so that the amount of developer placed on the paper is reduced with respect to the image portion having a specific characteristic that is likely to cause fixing tailing. . By this process, a large number of gaps can be formed in the image area, and water vapor generated during fixing can be released, thereby suppressing the occurrence of fixing tailing. The printing apparatus control unit 400 separates image data (RIP data) into image areas such as line images, character images, and photographic images (image area separation) for image portions having specific characteristics that are likely to cause fixing tailing. Identify) by recognizing. Then, the printing apparatus control unit 400 performs pattern matching on the image portion of the line image or the character image using an image thinning pattern for determining an image portion having a specific feature in which fixing tailing is likely to occur. As a result, a pixel to be subjected to thinning processing is determined, and thinning is performed by making this pixel a white pixel.

  FIG. 6 is a flowchart regarding the fixing tail correction process in the controller unit 410 of the printing apparatus control unit 400. First, the printing apparatus control unit 400 performs image area separation on the RIP data described above (S200). Next, the printing apparatus control unit 400 determines whether the image is a line image or a character image from the result of the image area separation (S201). If it is determined in S201 that the image is a line image or a character image, the printing apparatus control unit 400 performs a thinning process (S202). If it is determined that the image is neither a line image nor a character image, the thinning process is not performed. For example, for a photographic image, since there are many dot portions such as a solid portion and a halftone, fixing tailing hardly occurs. Therefore, the fixing tail correction process is not performed on the image portion of the photographic image. On the other hand, a line image and a character image are more likely to cause fixing tailing because there are generally more straight lines than a photographic image. Therefore, it is a target of fixing tail correction processing (thinning processing).

  Processing performed by the digital registration processing unit 452 will be described with reference to FIGS. The digital registration processing unit 452 performs correction processing in which the controller unit 410 digitally corrects an inclination at the time of image formation caused by the mounting accuracy of a lens or a mirror used when the printer control unit 301 outputs laser light. I do. The inclination at the time of image formation is such that, when a color image is formed, electrostatic latent images of a plurality of colors such as C, M, Y, and K as process colors are formed on the plurality of photosensitive drums 302, respectively. An image shift is generated when the images are transferred and superposed at 306. An example of such an inclination during image formation is shown in FIG. In order to correct the image shift, RIP data (image data) is moved in the sub-scanning direction for each color based on the transfer point, the transfer width in the sub-scanning direction, and the transfer direction stored in advance in the transfer point storage unit 453. Thus, digital correction processing is performed. The “transfer point” means a portion arranged at equal intervals in the main scanning direction, and at each transfer point, how much the image data is moved (shifted) in which direction (forward direction or reverse direction) in the sub-scanning direction. ) Information (transfer information) is related. Such a digital registration process is shown in FIG. By distorting the image data in the opposite direction to the tilt at the time of image formation, the tilt of the image when the electrostatic latent image is formed is reduced.

  FIG. 9 shows a flowchart relating to digital registration processing in the controller unit 410. First, it is determined whether or not the RIP data after the tailing process is a color image (S300). If it is determined that the image is a color image, the digital registration processing unit 452 performs the following processing. That is, the transfer point stored in the transfer point storage unit 453 is referred to (S301), and the correction processing is digitally performed by moving the image data in each color in the sub-scanning direction according to the transfer information associated with each transfer point. This is performed (S302). If it is not determined to be a color image, digital correction processing is not performed.

  Next, the processing of S109 to S111 in FIG. 19 will be described with reference to FIG. The printed document reading unit 500 includes a paper detection sensor 511 and a line sensor 512. The print document reading unit 500 detects the presence of the paper at the edges of both ends of the black paper transport belt 513 using the paper detection sensor 511, thereby detecting the paper of the output printed matter 50 (S109). The print original reading unit 500 reads the image data of the output printed matter 50 by using the line sensor 512 with the detection signal of the presence or absence of paper of the paper detection sensor 511 as a trigger (S110). At this time, as the operation of the line sensor, reading according to the print document reading mode received in S108 is performed. There are a plurality of print document reading modes depending on the paper size, single side / double side, color / monochrome, and the like. Then, after reading the image data of the print document, the print document reading unit 500 transmits the read image data to the inspection control unit 600 (S111), and sends the output printed matter 50 to the print document discharge control unit 700 (S112). .

  The process of S113 to S124 in FIG. 19 will be described with reference to FIGS. The inspection control unit 600 receives the setting information set in the reference image data 1000 and S100 from the printing apparatus control unit 400 via the network 3 (S113). An example of the reference image data 1000 is shown in FIG. As the reference image data 1000, image data transmitted from the printing apparatus control unit 400 to the printer unit 300 is used. That is, the reference image data 1000 here is reference image data before image processing (reverse correction processing) having characteristics opposite to those of the image processing in S104.

  Further, the inspection control unit 600 determines the reading operation mode of the line sensor 512 such as the paper size and single-sided / double-sided reading from the job attribute information, and instructs the print document reading unit 500 to do so. Next, the inspection control unit 600 receives image data (inspection scan image data 1100) read by the line sensor 512 from the print document reading unit 500 and stores it in a storage device in the inspection control unit 600. An example of the inspection scan image data 1100 is shown in FIG. Note that the inspection scan image data 1100 is also simply referred to as scan image data 1100.

  Further, the inspection control unit 600 performs preprocessing for comparing and collating the inspection scan image data 1100 and the reference image data 1000 read by the print document reading unit 500. Specifically, first, when the reference image data 1000 is a color image, the inspection control unit 600 performs a digital correction process (digital registration process) of an inclination at the time of image formation caused by the mounting accuracy of a lens or a mirror. ) And reverse correction processing that reverses the characteristics. Secondly, the inspection control unit 600 performs a reverse correction process on the reference image data 1000 so that the characteristics are opposite to those of the fixing tail correction process performed in step S104. In these reverse correction processes, the inspection control unit 600 uses transfer point information for the reverse correction process, transfer information associated with each transfer point, and information on the image thinning pattern, as will be described later. These pieces of information will be described as being stored in advance in the storage device in the inspection control unit 600, but may be information acquired from the printing device unit. These pieces of information differ depending on the characteristics of the printer unit, and are stored for each printing device unit.

  Third, descreen processing is performed on the reference image data 1000 of the binary image. This is because the gradation is matched with the scanned image data 1100 for inspection of a multi-valued image. Fourth, resolution conversion processing is performed on both images. This is for the purpose of matching the resolutions of both images and for reducing the necessary and sufficient resolution to improve comparison and collation performance. Fifth, color space conversion processing is performed on both images. This is because the scanner characteristics of the inspection scan image data 1100 are reflected in the reference image data 1000. The inspection control unit 600 compares and collates images using the image-processed reference data and inspection scan image data, and transmits the collation result to the printing apparatus unit 10.

  Next, reverse correction processing of digital registration processing will be described. First, the inspection control unit 600 refers to a transfer point for reverse correction processing, a transfer width in the sub-scanning direction, and a transfer direction that are stored in advance in a storage device in the inspection control unit 600. The inspection control unit 600 performs the following processing according to the transfer points and the transfer information associated with each transfer point. That is, as shown in FIG. 15, the image data of each color is shifted in the sub-scanning direction by a direction opposite to the correction direction and correction amount in the digital registration process described in FIG. As a result, the reference image data 1000 after the digital registration process can be restored to the image before the digital registration process. FIG. 16 is a flowchart relating to the reverse correction process of the digital registration process in the inspection control unit 600. First, the inspection control unit 600 determines whether the reference image data 1000 is a color image (S500). If it is determined that the reference image data 1000 is a color image, the inspection control unit 600 performs the following processing. In other words, the transfer point stored in advance is referred to (S501), and the above-described process of restoring the movement of the image data of each color in the sub-scanning direction (the reverse correction process of the digital registration process) is performed (S502). If it is not determined to be a color image, reverse correction processing is not performed.

  Next, the reverse correction process of the fixing tail correction process will be described. The image data to be subjected to the reverse correction process is an image that has been reversely corrected by the reverse correction process of the digital registration process, that is, an image similar to the image data that has been processed by the tailing processing unit 451 in FIG. It is. First, the inspection control unit 600 determines whether image data has been subjected to thinning processing by pattern matching with an image thinning pattern stored in advance in a storage device in the inspection control unit 600. Then, as shown in FIG. 13, the inspection control unit 600 complements the image so as to fill a large number of gaps generated by the thinning process in the image determined to have been thinned, and thus the original image (that is, the tint block in FIG. 3). Return to the image after processing by the processing unit 442. This is because, when the reference image reflects only the fixing tail correction process and the inspection scan image reflects the fixing tail correction process and the characteristics of the printer unit, the two images are matched. It is.

  FIG. 14 shows a flowchart relating to the reverse correction process of the tailing process in the inspection control unit 600. This flowchart processing is processing for all the pixels of the reference image data 1000, but in the following description, one processing target pixel will be described as an example. First, the inspection control unit 600 performs pattern matching using image thinning patterns on image data of a predetermined area including pixels to be processed of the reference image data 1000. Thereby, it is determined whether the image data of the pixel to be processed has been thinned (S400). Note that the thinned image data is image data whose density value is set to a minimum value (for example, 0). When it is determined that the image data of the pixel to be processed has been subjected to the thinning process, the inspection control unit 600 performs a correction process (inverse correction process of the thinning process) so as to interpolate the image data of the pixel to be processed. It performs (S401). In this reverse correction process, the density value of the image data of the processing target pixel may be set to a maximum value (for example, 255), or may be an average value of the density values of pixels around the processing target pixel. If it is determined that the image has not been subjected to the thinning process, the reverse correction process is not performed. As described above, the image data before being subjected to the image processing of S104 is generated by performing the image processing with the characteristics reverse to those of the image processing performed in S104 on the reference image data 1000. Then, this image data is obtained as reference image data to be compared with the inspection scan image data 1100, and image collation processing between the reference image data and the inspection scan image data is performed as described below.

  The image matching process in step S119 for determining whether or not the printed matter is correctly printed in the inspection control unit 600 will be described with reference to the flowchart of FIG. First, the coordinates of each pixel in the sub-scanning direction and the main scanning direction are set to Y = 0 and X = 0, respectively (S700, S701). Next, as illustrated in FIG. 17, one pixel of the inspection scan image data 1100 is set as a target pixel 1110, and each pixel (reference pixel) in the square area centering on this pixel and the same coordinate pixel in the reference image data 1000 is used. 1010) is referred to (S702, S703). Next, the pixel density is compared between the target pixel and each reference pixel (S704). It is determined whether the density difference from an arbitrary reference pixel 1010 is within a certain value (for example, a value set by the user) (S705). If it is within a certain value, it is determined that the target pixel 1110 of the inspection scan image data 1100 exists in the square area of the reference image data 1000, and the target pixel 1110 is a correct pixel (S706). If the difference data from all the reference pixels 1010 exceeds the certain value, it is determined that the target pixel 1110 of the inspection scan image data 1100 does not exist in the square area of the reference image data 1000 and the target pixel is a defective pixel. (S707).

  The above collation is performed for all the pixels of the inspection scan image data 1100 (S708 to S711). Next, the inspection control unit 600 determines whether or not the number of defect data is equal to or less than a threshold value set in advance by the user (S712). As a result, if the number of defect data is equal to or less than the threshold value set in advance by the user (Yes in S712), the inspection control unit 600 determines that the inspection scan image data 1100 is acceptable (S713). If the threshold is exceeded (No in S712), the scanned image data for inspection 1100 is determined to be unacceptable (S714). Thereafter, the print document discharge control unit 700 performs discharge control of the output printed matter 50 sent to the print document discharge control unit 700 in accordance with the inspection result received from the inspection control unit 600.

  As described above, the quality of the printed matter can be determined in consideration of various types of image processing applied to the RIP data after RIP development.

  In the second embodiment, each configuration, its operation and control are the same as those shown in FIGS. 1 to 19 of the first embodiment. Therefore, only the difference will be described.

  In this embodiment, whether the RIP data (first image data) generated in step S102 is used as the reference image data 1000 or the image data (second image data) processed in step S104 is used. Is related to in-line inspection. When the first image data is used as reference image data, it is not necessary to reversely correct the printer characteristic correction processing as in the first embodiment. However, when page composition processing or page layout processing for providing copy-forgery-inhibited pattern information is performed for the input job, the page layout processing is not reflected in the RIP data that is the first image data. It becomes an image difference, which may result in an erroneous inspection. On the other hand, when the second image data is used as the reference image data, the page layout process is reflected, so that the image difference at the time of image comparison and verification is not obtained. However, it is necessary to reversely correct the printer characteristic correction processing described in the first embodiment, which takes a long processing time and leads to performance degradation. Therefore, in the present embodiment, whether the first image data or the second image data is used as the reference image data 1000 is switched in view of the above advantages.

  A processing flow in the printing apparatus unit according to the second embodiment will be described with reference to a flowchart of FIG. First, the user sets a print job and its inspection in the printing apparatus unit 10 (S600). Next, the printing apparatus unit 10 transmits print job settings and inspection settings to the inspection control unit 600 (S601). Next, a print job is started (S602), RIP data is generated (S603), and it is determined whether the job is a page layout process (S604). In the case of a job that does not perform page layout processing, the printing apparatus unit 10 transfers the generated RIP data to the inspection control unit 600 as reference image data 1000 for inspection (S605). When the reference image data 1000 is transferred, the printing apparatus unit 10 also transfers information (first determination information) indicating that the reference image data 1000 is RIP data to the inspection control unit 600. Thereafter, the printing apparatus unit 10 performs printer characteristic correction processing on the RIP data (S606). In the case of a job that performs page layout processing, the printing apparatus unit 10 performs page layout processing on the generated RIP data (S607). Thereafter, printer characteristic correction processing is performed on the RIP data (S608). In the case of a job for performing page layout processing, the print image data is transferred to the inspection control unit 600 as reference image data 1000 for inspection (S609). When the reference image data 1000 is transferred, the printing apparatus unit 10 also transfers information (second determination information) indicating that the reference image data 1000 is image data that requires reverse correction processing to the inspection control unit 600. . Then, the printing apparatus unit 10 prints an image on the paper from the generated print image data (S610), and discharges the printed matter from the printing apparatus unit 10 to the print original reading unit 500 (S611).

  A processing flow in the inspection control unit of the second embodiment will be described with reference to the flowchart of FIG. The inspection control unit 600 receives the print job and inspection user settings from the printing apparatus unit 10 (S613), and instructs the print document reading unit 500 in the print document reading mode (S614). Next, the inspection control unit 600 receives the reference image data 1000 from the printing apparatus unit 10 (S615), and receives the inspection scan image read by the print document reading unit 500 (S616). Next, the inspection control unit 600 determines whether or not the received reference image data 1000 is RIP data (first image data) based on the first or second determination information (S617). When the received reference image data 1000 is RIP data (first image data), the printer characteristics correction process is not performed in the printing apparatus unit 10, and the reverse process is not performed. On the other hand, when the received reference image data 1000 is not the RIP data but the image data (second image data) transferred in step S609, the printer characteristic correction process is reversed (S618). Further, dereference processing, resolution conversion processing, color space conversion image collation, and comparison image preprocessing are performed on the reference image data 1000 and the inspection scan image data 1100 (S619). These two images are compared and collated (S620). Further, the collation result is transmitted to the print document discharge control unit 700 (S621). The processing flow in the printing apparatus section and the processing flow in the inspection control section are the differences from the first embodiment. Since other processes are the same as those in the first embodiment, description thereof is omitted.

[Other Examples]
The present invention can also be realized by executing the following processing. That is, software (program) that realizes the functions of the above-described embodiments is supplied to a system or apparatus via a network or various storage media, and a computer (or CPU, MPU, or the like) of the system or apparatus reads the program. It is a process to be executed.

Claims (8)

Read image acquisition means for obtaining a read image by reading a printed matter printed based on an image after image processing for which image processing for printing in a printing apparatus has been performed;
Reference image acquisition means for obtaining, as a reference image, an image before being subjected to the image processing by performing image processing having characteristics opposite to those of the image processing on the image after the image processing;
An inspection apparatus comprising: a determination unit that determines the quality of the printed matter by comparing the reference image with the read image. The image processing includes digital registration processing for moving an image in the sub-scanning direction at a transfer point arranged in the main scanning direction,
The reference image acquisition unit performs the digital registration at the transfer point with respect to the image after the image processing so as to cancel the movement in the sub-scanning direction of the image at the transfer point performed by the printing apparatus. 2. The inspection apparatus according to claim 1, wherein an image before the digital registration process is obtained as the reference image by performing a process of moving the image in a direction opposite to the movement of the image by the process. The image processing includes thinning processing using an image thinning pattern when the image is a line image or a character image,
The reference image acquisition unit determines whether the image has been subjected to the thinning process by pattern matching using the image thinning pattern, and performs pixel thinning by the thinning process on the image after the image processing. The image before performing the thinning process is obtained as the reference image by performing a process of interpolating an image determined to have been subjected to the thinning process so as to cancel out. Inspection equipment. Means for reading a printed matter printed based on the image after image processing to obtain a read image;
Determining means for determining whether or not to perform image processing having characteristics opposite to those of the image processing on the image after image processing;
Means for obtaining an image before the image processing as a reference image by performing the image processing when it is determined by the determining means that the image processing having the opposite characteristics is performed;
An inspection apparatus comprising: a unit that determines the quality of the printed matter by comparing the reference image with the read image.   5. The inspection apparatus according to claim 4, wherein the determination unit determines whether to perform image processing having characteristics opposite to those of the image processing, depending on whether page layout processing has been performed. Obtaining a read image by reading a printed matter printed on the printing apparatus based on the image after image processing;
Steps for obtaining an image before the image processing as a reference image by performing image processing having characteristics opposite to those of the image processing on the image after the image processing;
And a step of determining the quality of the printed matter by comparing the reference image with the read image. Reading a printed matter based on the image after image processing to obtain a read image;
A determination step of determining whether or not to perform image processing having characteristics opposite to those of the image processing on the image after the image processing;
If it is determined by the determination step that the image processing with the reverse characteristics is performed, the image processing is performed to obtain an image before the image processing as a reference image;
And a step of determining the quality of the printed matter by comparing the reference image with the read image.   The program for functioning a computer as each means as described in the inspection apparatus of any one of Claims 1-5.

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