Inspection apparatus, control method of inspection apparatus, and inspection system

Abstract

The invention relates to an inspection apparatus, a control method of the inspection apparatus, and an inspection system. An image printed on a pre-printed sheet on which information of a specific color is printed in advance and the information are scanned, the specific color included in image data scanned and acquired is removed, and an image acquired after the specific color is removed is inspected based on a reference image.

Description

Technical Field

[0001] The present invention relates to an inspection device, a control method of the inspection device, and an inspection system. Background Art

[0002] In recent years, a product check apparatus has been proposed, which can check a sheet (hereinafter referred to as a printed sheet) printed by a printing device during sheet conveyance. In the process of checking the printed sheet, the product check apparatus scans an image on the conveyed printed sheet to determine whether the printing on the printed sheet is normal based on image analysis of the scanned image. The product check apparatus can detect printing failure or color drift. The product check apparatus can also print an image on a pre-printed sheet on which an image is pre-printed (hereinafter, the pre-printed image is referred to as a pre-printed image) and check the image. According to Japanese Patent Application Laid-Open No. 2007-310567, when performing an image check on a pre-printed sheet, it is necessary to confirm whether the print data is printed correctly, generate mask data based on the print data, and set the surrounding area of ​​the print data as an inspection area. Summary of the invention

[0003] However, according to Japanese Patent Application Laid-Open No. 2007-310567, since the inspection area is limited to the surrounding area of ​​the print data, there arises a problem that the entire sheet is not inspected.

[0004] According to one aspect of the present invention, there is provided an inspection device, comprising: a scanning unit configured to scan an image printed on a pre-printed sheet on which information of a specific color is pre-printed and to scan the information; a processing unit configured to remove the specific color included in image data scanned and acquired by the scanning unit; and an inspection unit configured to inspect, based on a reference image, an image acquired after the processing unit removes the specific color.

[0005] Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 is a block diagram of an entire inspection system including an image processing apparatus according to an embodiment.

[0007] Figure 2 is a block diagram illustrating the functional arrangement of an image processing apparatus according to the embodiment.

[0008] Figure 3: is a flowchart illustrating a processing procedure of a product verification process performed in the image processing apparatus according to the embodiment.

[0009] Figure 4 is a flowchart illustrating a processing procedure of an inspection setting process performed in the image processing apparatus according to the embodiment.

[0010] Figure 5 is a flowchart illustrating a processing procedure of an inspection execution process performed in the image processing apparatus according to the embodiment.

[0011] Figure 6 An example of a result display screen according to an embodiment is illustrated.

[0012] Figure 7 An example of a display screen according to the embodiment is illustrated.

[0013] Figure 8 An example of a display screen according to the embodiment is illustrated.

[0014] Fig. 9 An example of a display screen according to the embodiment is illustrated.

[0015] Fig.10 is a detailed flowchart of the LUT generation process according to the embodiment.

[0016] Fig.11A and Fig. 11B is a schematic diagram illustrating an example of three-dimensional LUT processing according to the embodiment.

[0017] FIG. 12A to FIG. 12C An example of removing a designated color according to an embodiment is illustrated.

[0018] Fig.13A and Fig. 13B An example of parameters for specifying color removal according to an embodiment is illustrated.

[0019] FIG. 14A to FIG. 14D Sample images before and after processing according to an embodiment are illustrated.

[0020] Fig.15 is a flowchart illustrating a processing procedure of an inspection setting process performed in the image processing apparatus according to the embodiment.

[0021] FIG. 16A to FIG. 16C An example of a display screen according to the embodiment is illustrated.

[0022] Fig.17 is a flowchart illustrating a processing procedure of an inspection setting process performed in the image processing apparatus according to the embodiment. DETAILED DESCRIPTION

[0023] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that the following embodiments are not limited to the present invention described in the claims, and the combination of all features described in the present embodiments is not necessarily required for the solution of the present invention. It should be noted that the same reference numerals are given to the same components, and their descriptions will be omitted.

[0024] First embodiment

[0025] Check the system configuration

[0026] Hereinafter, a first embodiment of the present invention will be described. Figure 1 A configuration example of the entire inspection system is described, which includes the image processing apparatus (inspection apparatus) 100 according to the present embodiment and is configured to output a print product and perform inspection.

[0027] The inspection system according to the present embodiment includes at least an image processing device 100 and a printing device 190. A print server 180 may be included in the inspection system. The print server 180 has a function of generating a print job of an original document to be printed and inputting the print job to the printing device 190. A plurality of external devices not shown in the figure may be connected to the print server 180 via network communication, and the print server 180 may receive a print job generation request, print data, etc. from these external devices. The print server 180 may also perform a raster image processor (RIP) process for a reference image. Specifically, in the RIP process for the reference image, an image is generated by converting the resolution (e.g., from 600dpi to 300dpi), while in the RIP process for the print data, an image is generated without reducing the resolution.

[0028] The printing device 190 has a function of forming an image on a recording medium (printing sheet) based on a print job input from the print server 180. A device based on an offset printing method, an electrophotographic method, an inkjet method, or the like can be applied as the printing device 190. According to the present embodiment, the description provided assumes a printing device based on an electrophotographic method, but is not intended to limit the present invention. The printing device 190 includes a sheet feeding unit 191, and a user sets a printing sheet in the sheet feeding unit 191 in advance. When a print job is input, the printing device 190 forms an image on the front side or both sides while conveying the printing sheet set in the sheet feeding unit 191 along a sheet conveying path 192, and conveys the sheet to the image processing device 100.

[0029] The image processing apparatus 100 of the present embodiment performs an inspection process of verifying whether there is an image defect on a sheet (also referred to as paper, recording medium, etc.) (i.e., a print product) on which an image is formed by a printing device 190 and conveyed through a sheet conveying path 192. In other words, the image processing apparatus 100 acts as an inspection apparatus. It should be noted that the overall process of checking whether there is an image defect is referred to as an inspection process herein. The process included in the inspection process of detecting a plurality of types of corresponding image defects is referred to as a defect detection process (or simply a detection process). The image processing apparatus 100 includes a central processing unit (CPU) 101, a random access memory (RAM) 102, a read-only memory (ROM) 103, a main storage device 104, and an image scanning apparatus 105. The image processing apparatus 100 also includes a printing apparatus interface (I / F) 106, a general interface (I / F) 107, a user interface (UI) panel 108, and a main bus 109. The image processing apparatus 100 further includes a sheet conveying path 110 for printed products connected to a sheet conveying path 192 of a printing device 190, an output tray 111 for printed results that have passed inspection, and an output tray 112 for printed products in which defects have been found and rejected in inspection. It should be noted that the classification of printed products may be more detailed than the two types of pass and reject in image inspection.

[0030] The CPU 101 is a processor configured to control the entire image processing apparatus 100. The RAM 102 serves as a main memory, a work area, etc. of the CPU 101. The ROM 103 stores a group of programs executed by the CPU 101. The main storage device 104 stores applications executed by the CPU 101, data for image processing, etc. The image scanning device (scanner) 105 can scan a single side or both sides of a printed product conveyed from the printing device 190 on the sheet conveying path 110, thereby acquiring image data. Specifically, the image scanning device 105 scans a single side or both sides of a conveyed printed product by using one or more scanning sensors arranged near the sheet conveying path 110. The scanning sensor may be arranged only on a single side including the front and back sides of the conveyed printed product, or may be arranged on both sides including the front and back sides of the conveyed printed product in order to scan both sides simultaneously. When the scanning sensor is provided only on one side, after scanning one side, the scanning sensor can scan the other side again by reversing the front and back sides of the conveyed print product using a double-sided sheet conveying path (not shown) in the sheet conveying path 110 .

[0031] The printing device I / F 106 is connected to the printing device 190 , and can synchronize the processing timing of print products with the printing device 190 and communicate each other's operation states.

[0032] The general I / F 107 is a serial bus interface such as a universal serial bus (USB) or IEEE1394, which is used by the image processing apparatus 100, through which the user can take out data such as a log or input any data. The UI panel 108 is, for example, a liquid crystal display (display unit). The UI panel 108 serves as a user interface of the image processing apparatus 100, and displays the current situation or setting to notify the user. The UI panel 108 may be a touch panel liquid crystal display, and accepts instructions from the user when the user operates the displayed button.

[0033] The main bus 109 connects each unit of the image processing apparatus 100. Each part inside the image processing apparatus 100 or the inspection system can be operated according to the instruction from the CPU 101 through the main bus 109. For example, the sheet conveying path 110 can be synchronously moved, or the path can be switched to convey the print product to the output tray 111 that passes the print product or the output tray 112 that rejects the print product according to the inspection result. In addition to the CPU, a graphic processing unit (GPU) may be included.

[0034] The image processing apparatus 100 according to the present embodiment performs an inspection process to be described below based on image data acquired by scanning the printed product by the image scanning device 105 while the printed product conveyed from the printing device 190 is conveyed in the sheet conveying path 110. As a result of the inspection process, when the printed product passes the inspection, the printed product is conveyed to the output tray 111 for passing the printed product, and when the printed product fails the inspection, the printed product is conveyed to the output tray 112 for rejecting the printed product. In this way, only the printed products with guaranteed quality can be collected in the output tray 111 for delivery as the printing result.

[0035] Product Verification Overall Process

[0036] Next, we will refer to Figure 2 and Figure 3 The overall flow from the registration operation before the start of the examination to the examination execution is described. The processing described below is realized when the CPU 101 reads out the program stored in the ROM 103 onto the RAM 102 to execute the program, for example. Hereinafter, the step number of each process is indicated by "S" followed by a number. Figure 2 is a block diagram illustrating the functional arrangement of the image processing apparatus 100 . Figure 3 is a flowchart illustrating the processing procedure of the inspection process.

[0037] In step S301 , the image acquisition unit 201 registers an image set as a reference image for inspection.

[0038] The image acquisition unit 201 acquires a reference image (reference image data) from the RAM 102 or the main storage device 104. However, it should be noted that the reference image data is pre-stored in the RAM 102 or the main storage device 104. Image data after RIP processing that analyzes a print job to generate image data is set as a reference image.

[0039] Next, in step S302 , the checking process selection unit 202 sets various checking parameters such as the checking level and whether to check the preprinted sheet according to the user's checking setting.

[0040] It should be noted that the details of step S302 according to the present embodiment will be described below.

[0041] Next, in step S303, the image acquisition unit 201 acquires the inspection target image by causing the image scanning device 105 to scan the print product conveyed from the printing device 190. Note that a configuration in which the image scanning device 105 scans the inspection target image in advance and acquires the scan data held in the main storage device 104 may be adopted.

[0042] Furthermore, when checking a preprinted sheet is selected in step S302 , the color conversion unit 203 performs a color correction process, which will be described below, on the checking target image.

[0043] Then, the alignment processing unit 204 and the image inspection unit 205 align the inspection target image after the color correction processing with the reference image, and also perform defect detection processing. The details of step S303 in this embodiment will be described below.

[0044] In step S304 , the inspection result output unit 206 generates the inspection result to be displayed on the UI panel 108 , and the process ends.

[0045] Figure 6 An example of a result display screen according to the present embodiment is illustrated. An overall image 1202 of an inspection corresponding image is displayed on a UI screen 1201. A defect 1203 is determined to be a point defect, and a phrase "point defect" is also displayed near the defect 1203. A defect 1204 is determined to be a line defect, and a phrase "line defect" is also displayed near the defect 1204. In addition, as indicated by reference numerals 1205 and 1206, the coordinates of the corresponding defect may also be displayed.

[0046] The overall flow from the registration operation before the start of the examination to the examination execution according to the present embodiment has been described above.

[0047] Check setting processing

[0048] Next, we will refer to Figure 4 and Figure 7 The processing procedure of checking settings in S302 according to the present embodiment is described. Figure 4 is a flowchart illustrating the processing procedure of checking settings. Figure 7 An example of a UI specified to set the inspection setting is illustrated.

[0049] In step S401, the inspection process selection unit 202 sets the inspection items and their inspection levels for detecting defects in the printed image inspection of UI 707. The inspection items in the printed image inspection refer to items related to the defect features that are expected to be detected when inspecting the printed product, and are, for example, point defects (point defects) or line defects (stripe defects). The detection level refers to a parameter that is set in grades for each detected defect feature, from what size is determined to be a defect. For example, there are five grades from level 1 to level 5, and compared with level 1, defects that are thinner and smaller in size can be detected at level 5. In addition, the level can be set for the corresponding inspection item, for example, the inspection level 5 is set for spots, and the inspection level 4 is set for stripes. UI 707 indicates that the user has selected level 4 as the inspection level setting for defects (dots), and has selected level 4 as the inspection level setting for defects (stripes).

[0050] In step S402, the inspection process selection unit 202 performs setting of the inspection sheet. The setting of the inspection sheet indicates whether the inspection sheet is a preprinted sheet on which an image is preprinted. According to the present embodiment, a case where a specific color of a preprinted sheet on which information of a specific color is preprinted is designated as a designated color will be described. Then, by removing the designated color from the preprinted image, a comparison check with a reference image can be realized without acquiring information of the image printed on the preprinted sheet.

[0051] The UI 709 illustrates an example in which the inspection sheet is a preprinted sheet. By selecting the radio button 708, the user notifies the inspection processing selection unit 202 that the inspection sheet is a preprinted sheet.

[0052] In step S403, the check processing selection unit 202 determines whether the check is a check of a preprinted sheet depending on whether the radio button 708 is selected on the UI 709. When it is determined that the check is a check of a preprinted sheet, the flow proceeds to step S404. When it is determined that the check is not a check of a preprinted sheet, the process ends.

[0053] In step S404, the inspection processing selection unit 202 accepts the color of the pre-printed image from the user. For example, the radio button 711 can be selected to set red as the specified color. The radio button 712 can be selected to set green as the specified color. The radio button 713 can be selected to set blue as the specified color. It should be noted that in addition to the three colors of red, blue and green, other colors can also be selected as the specified color type. When the inspection processing selection unit 202 accepts the user's selection of the color that the specified color is expected to be removed, the inspection processing selection unit 202 accepts pressing any one of the radio button 711 that sets red to the specified color, the radio button 712 that sets green to the specified color, and the radio button 713 that sets blue to the specified color to accept the instruction to remove the desired color. According to the present embodiment, the case where the user selects the radio button 711 to set red to the specified color will be described. It should be noted that multiple colors can be selected.

[0054] In step S404, the check processing selection unit 202 stores the removal color selected by the user as a setting value in the RAM 102. In addition to the above, in step S404, more detailed setting adjustments can be selected for the specified color removal. For example, the following settings can be made: after deciding the specified color, the removal range of the specified color is expanded, and colors spanning a wider range can be removed. The details of the more detailed setting adjustments for the specified color removal will be described below. With this configuration, even when the specified color is a color that is difficult to specify or when the color of the edge end changes due to the influence of printing or scanning, it is still possible to easily set it.

[0055] In step S405, the inspection process selection unit 202 calculates a three-dimensional lookup table (LUT) that can be used to remove the accepted designated color component. The details will be described below.

[0056] The processing procedure of the check setting according to the present embodiment has been described above.

[0057] Check execution processing

[0058] Next, we will refer to Figure 5 The processing procedure of the inspection execution processing performed in step S303 by the color conversion unit 203, the alignment processing unit 204, and the image inspection unit 205 according to the present embodiment is described. Figure 5 303 is a flowchart illustrating the processing procedure of the check execution processing in step S303.

[0059] First, in S501, the color conversion unit 203 determines whether the inspection is an inspection of a preprinted sheet. Whether the inspection is an inspection of a preprinted sheet is determined depending on whether the radio button 708 indicating that the inspection is to be performed on a preprinted sheet is pressed in step S402. When it is determined that the present inspection is an inspection of a preprinted sheet, the flow moves to step S502, and the color conversion unit 203 performs correction processing on the preprinted sheet. When it is determined that the present inspection is not an inspection of a preprinted sheet, the color conversion unit 203 does not correct the inspection image, and the flow moves to step S503.

[0060] In S502, the color conversion unit 203 performs correction processing on the inspection target image by using the LUT generated in step S405. The details of the correction processing will be described below.

[0061] In S503, the alignment processing unit 204 aligns the reference image with the inspection target image. Here, a method such as affine transformation in the prior art is proposed for alignment.

[0062] In S504, the image inspection unit 205 acquires a difference image between the reference image and the inspection target image, and the process proceeds to S505. Herein, the difference image refers to an image acquired by, for example, comparing the reference image with the inspection target image for each pixel and acquiring the difference between the pixel values ​​of each pixel (for example, the density value of each of R, G, and B).

[0063] In S505 , the image inspection unit 205 performs filtering processing to highlight a specific shape of the difference image acquired in S504 .

[0064] In S506, the image inspection unit 205 performs binarization processing on the difference image subjected to the highlighting processing so that when the difference exceeds the threshold value, the binary value becomes "1", and when the difference value is equal to or smaller than the threshold value, the binary value becomes "0".

[0065] In S507, the image inspection unit 205 determines whether there is a pixel whose difference exceeds the threshold value and whose binary value becomes "1" in the image subjected to the binarization processing. When the pixel exists, the process enters S508, and when the pixel does not exist, it is assumed that there is no defective position and the current processing ends. In S508, assuming that there is a defective position, the image inspection unit 205 stores the type of defect detection processing used to detect the defective position in association with the coordinates of the defective position. Then, the processing ends.

[0066] 3D LUT generation method for specified color removal

[0067] Will refer to Fig.10The diagram shows a flow of calculating a three-dimensional LUT that can be used to remove a designated color component accepted by the inspection process selection unit 202. This flow is executed by the inspection process selection unit 202, and is realized when the CPU 101 included in the image processing apparatus 100 executes a control program.

[0068] The data to be input includes R, G, and B on the output side of the three-dimensional LUT, and the signal values ​​of all tables (according to the present embodiment, since the increment of the value is 15, there are 16×16×16 tables) are processed. In addition, as parameters for processing, the saturation width threshold, hue center angle, and hue width threshold of each designated color are input. It should be noted that the three-dimensional LUT used for processing and the input parameters for processing are stored in the ROM 103. The input parameters will be described below.

[0069] In step S1001, when any one of red, green and blue is designated as a designated color, input Ri, Gi and Bi are converted from the RGB color space to a color space of brightness and color difference (eg, a YUV color space). The conversion from RGB to YUV is based on the following expression.

[0070] Yi=0.299×Ri+0.587×Gi+0.114×Bi

[0071] Ui=-0.169×Ri-0.331×Gi+0.50×Bi

[0072] Vi=0.50×Ri-0.419×Gi-0.081×Bi

[0073] It should be noted that "i" indicates the LUT number to be processed in all tables. Here, "i" takes a value between 0 and 4095.

[0074] In step S1002, the distance from the origin (0, 0) to the (Ui, Vi) value is calculated based on the converted color difference signal (Ui and Vi among Yi, Ui and Vi). For example, as a calculation expression, the calculation is performed by the following expression.

[0075] DISTi=sqrt((Ui×Ui)+(Vi×Vi))

[0076] Herein, the calculated value is referred to as the saturation value.

[0077] In step S1003, it is determined whether the calculated saturation value is a saturation higher than a certain threshold value (saturation value threshold value) or a saturation lower than a certain threshold value (saturation value threshold value). The saturation value threshold value is preset and held as a parameter in ROM 103, and the determination is made by using the value. It should be noted that the saturation value threshold value may be a different value for each of the specified colors. When the calculated saturation value is higher than the saturation value threshold value (in the case of high saturation), the process proceeds to step S1004, and when the calculated saturation value is lower than the saturation value threshold value (in the case of low saturation), the process proceeds to step S1012.

[0078] At this time, when the saturation value of the input signal value is on the low saturation side relative to the saturation value threshold, it is determined not to be removed. On the other hand, when the saturation value of the input signal value is on the high saturation side relative to the saturation value threshold, it is set as a removal candidate. Herein, since low-saturation colors are not removed, removal of colors close to achromatic colors can be avoided. Fig. 12A The shadow patch area in is set as a removal candidate. It is assumed that the input LUT that can be drawn at the LUTα point is set as a removal candidate, and the input LUT that can be drawn at the LUTβ point is not removed.

[0079] In step S1004, the flow branches depending on which color among red, green, and blue is the designated color accepted by the inspection processing unit 202. When the designated color accepted by the inspection processing selection unit 202 is red, the flow proceeds to step S1005. When the designated color accepted by the inspection processing selection unit 202 is green, the flow proceeds to step S1006. When the designated color accepted by the inspection processing selection unit 202 is blue, the flow proceeds to step S1007.

[0080] In step S1005, step S1006, and step S1007, the hue center angle is set on the reference UV plane of the color specified from R, G, and B, respectively. Fig. 12B As shown in , when the origin on the UV plane is set as the center, the reference hue angle of each color is preset within the range of 0° to 359° clockwise from the vertex edge, maintained as a parameter, and the value is used. For example, Fig. 12B As shown in , the hue center angle of red is set to 340°, the hue center angle of green is set to 200°, and the hue center angle of blue is set to 100°.

[0081] In step S1008 , angles on the UV plane (U and V hue angles) are calculated based on the converted color difference signals (U and V among Y, U, and V). Fig. 12B An example of calculating a 350° angle for both LUTα and LUTβ is illustrated in FIG.

[0082] In step S1009, the angle difference (hue angle difference) between the U and V hue angles of each LUT calculated based on the reference hue angle set in step S1005, step S1006 or step S1007 and the color difference signal converted in step S1008 is calculated by the following expression.

[0083] DIFF_DEG = |(U and V hue angles of each LUT) - (reference hue angle)|

[0084] For example, when the designated color accepted by the inspection processing selection unit 202 is red, the angle difference between the value set in step S1005 and the value calculated in step S1008 is calculated. When the designated color accepted by the inspection processing selection unit 202 is red, the reference hue angle value set in step S1005 is 340°, and the U and V hue angles calculated in step S1008 are 350° in both LUTα and LUTβ. In view of this, the hue angle difference becomes 10° in both LUTα and LUTβ. In step S1010, it is determined whether the hue angle difference calculated in step S1009 is higher than the hue width threshold for each color. When the hue angle difference is equal to or lower than the hue width threshold, the process enters step S1011, and when the hue angle difference is higher than the hue width threshold, the process enters step S1012. When the reference hue angle difference is equal to or lower than the hue width threshold, the process enters step S1012. Fig. 12C When describing, it is determined whether the point is in an area where the hue angle enters an angle equivalent to the hue width threshold on both sides with the hue center angle of red as the center. For example, when the hue width threshold is set to 30 degrees, the point within the hue angle of red 340°±hue width threshold 30° is set as the removal range. Therefore, the color gamut of the hue angle from 340°-30° (=310°) to 340°+30° (=370° (=10°)) is removed.

[0085] In step S1011, the RGB values ​​of the LUT determined to be removed in step S1010 are changed to signal values ​​that are not printed. For example, in the case of a brightness signal value, the value is changed to (R, G, B) = (255, 255, 255) indicating white.

[0086] In step S1012 , the RGB values ​​of the LUT determined not to be removed in step S1010 are not changed, and the input signal is left as it is.

[0087] In step S1013, the flow branches depending on whether all LUTs have been checked (according to the present embodiment, since the increment of the value is 15, there are 16×16×16 tables). When the check of all signals is not completed, "i" is incremented to process the next LUT in step S1014. Then, the processing from step S1001 is performed. When the determination of all signals is completed, the processing ends.

[0088] According to the above-described processing, it is possible to generate an LUT capable of removing the input three-dimensional LUT according to the designated color component accepted by the inspection process selection unit 202 .

[0089] In addition, according to the present embodiment, a configuration in which setting values ​​are switched within several levels on the UI is described, which is also a configuration using preset parameter values. However, a configuration in which the parameter value can be directly adjusted after a UI in which the user can directly change the parameter is prepared may also be adopted.

[0090] Remove range adjustments

[0091] Fig.13A An example of parameters when "expanding the removal range" indicated by reference numeral 714 is specified in step S403 in a mode in which the removal range is wider is illustrated. A value that can be used to remove a wider range than the default range is maintained. By setting the saturation width threshold when specifying red, green, or blue to a value on the non-color side relative to the default value, a coefficient that can be used to remove an area farther from the non-color side is set. In addition, by setting the hue width threshold when specifying red, green, or blue to a hue wider than the default hue, a coefficient that can be used to remove an area farther from the other hue side is set. The default value of the hue center angle remains unchanged.

[0092] As a user-specified method, the user can use Figure 8 UI 800 for settings.

[0093] For example, when button 801 is selected, a parameter having a narrower range than the default range can be selected for removal. When button 803 is selected, a parameter having a wider range than the default range can be selected for removal.

[0094] It should be noted that, regarding the parameters described herein, the saturation width threshold is used for processing in step S1003, the hue center angle is used for processing in steps S1005, S1006, and S1007, and the hue width threshold is used for processing in step S1010.

[0095] Hue Adjustment

[0096] Fig. 13B4 shows an example of parameters when "hue adjustment" indicated by reference numeral 715 is specified in step S403. The hue center angle is changed relative to the default hue center angle. For example, when the specified color is red, the hue center angle can be changed to multiple levels of light magenta or light yellow relative to the default hue center angle. As a method for user specification, the above Fig. 9 For example, after selecting red as the designated color using radio button 711, when hue adjustment mode 715 is selected, the Fig. 9 900. Even if red is selected, the hue of the color to be removed, such as light magenta or light yellow-red, can be adjusted. For example, when it is desired to remove light magenta, button 902 is pressed to set the removal hue toward the magenta side. On the other hand, when it is desired to remove light yellow, button 903 is pressed to set the removal hue toward the yellow side. The adjusted setting is confirmed by the mark indicated by reference numeral 901.

[0097] It should be noted that, regarding the parameters described herein, the hue center angle is used for processing in steps S1005 , S1006 , and S1007 .

[0098] According to the present embodiment, the case where red is designated has been described, but setting may be made in the case of blue or green, and adjustment may be made toward the color direction of configuring the designated color.

[0099] In addition, it is possible to adjust "expanding the removal range" indicated by reference numeral 714 and "hue adjustment" indicated by reference numeral 715 separately. Only one of the settings may be designated, or both settings may be adjusted at the same time.

[0100] In addition, the designated color designated in the past can be stored and set. For example, using radio button 717, the color designated in the last inspection, the setting of hue adjustment, and the setting of removal range can be selected. Various settings for removing the color in the last inspection are stored in the main storage device 104. Similarly, radio button 718 is used for the user to specify the saved setting information of the removal color.

[0101] When the radio button 716 of "other than black" is selected, all colors except black are removed.

[0102] Specify color removal process

[0103] Next, a description will be given of a three-dimensional LUT process performed in the color conversion unit 203 and a method of designated color removal when a designated color is designated.

[0104] In the color conversion unit 203, when designated color removal is performed, for the image acquired by the image acquisition unit 201, R, G, and B images from which a preprinted image on a preprinted sheet is removed are generated from R, G, and B images having device-dependent characteristics.

[0105] Although various conversion methods have been proposed, a conversion process based on a three-dimensional LUT is also illustrated as an example.

[0106] Fig.11A An example of 4096 tables thinned out in increments of 15 is shown. Output R, output G, and output B (as output) in response to input R, input G, and input B (as input) are determined as a table. For example, the output when the input is (0,0,15) is converted to (0,0,15). When the input is not a value in increments of 15, the output is obtained based on interpolation calculations of adjacent numbers.

[0107] When designated color removal is performed, designated color removal is achieved by changing the three-dimensional LUT used in the conversion processing performed in the color conversion unit 203. For example, when the R, G, and B signals on the output side of the three-dimensional LUT correspond to the designated color accepted by the inspection processing selection unit 202, designated color removal is achieved by converting the contents of the three-dimensional LUT. In other words, the color is removed by converting the RGB of the designated color to a value (output R, output G, output B) = (255, 255, 255) set to represent white in the luminance signal. The three-dimensional LUT may be generated each time with the setting values ​​of the removal color and the removal area specified by the user, or the three-dimensional LUT may be maintained for each of the designated colors.

[0108] For example, when specifying blue (0,0,255), such as Fig. 11B As shown in , the output in response to the input (0,0,255) in index 15 becomes (255,255,255).

[0109] Advantages

[0110] Fig.14A The figure shows that the print data is printed on the pre-printed sheet ( Fig.14D ) is an example of an inspection image obtained by printing a pre-printed medium on a printed surface. Reference numeral 1401 indicates a pre-printed image printed in red. A stripe 1402 is a black stripe defect left at the time of printing.

[0111] Fig. 14BAn example of a check image acquired after the color conversion unit 203 removes a designated color (red according to the present invention) is illustrated. A case where the pre-print image 1401 is removed but a black stripe 1402 remains as indicated by reference numeral 1403 is observed.

[0112] Fig. 14C An example of a reference image is shown in the figure. Fig. 14B Remove the specified color from the check image with Fig. 14C By aligning and comparing with the reference image, stripes 1403 can be detected.

[0113] According to the present embodiment, the pre-printed image 1401 is removed and is not erroneously detected as a defect. Even in the case where a pre-printed sheet is inspected, the entire sheet can be inspected correctly. It should be noted that Fig.14D An example in which only a preprinted image is printed on a preprinted sheet is illustrated.

[0114] Advantages of this embodiment

[0115] According to the present embodiment, even when an image is printed on a preprinted sheet on which a preprinted image is printed in advance and then checked, the entire sheet can be correctly checked by specifying the color of the preprinted image and removing the color from the check image.

[0116] Second embodiment

[0117] According to the first embodiment, a method in which a user specifies the color of a preprinted image using a radio button on a UI is described. According to the second embodiment, a method in which a preprinted sheet on which a preprinted image is printed is scanned when checking settings and the color of the preprinted image is specified by the user will be described. According to this embodiment, by scanning the preprinted image in advance, the user is able not to select an erroneous color as the color of the preprinted image.

[0118] Hereinafter, only the differences from the first embodiment will be described in detail.

[0119] Check setting processing

[0120] Reference Fig.15 and FIG. 16A to FIG. 16C , the processing procedure of the check setting in S302 according to the present embodiment will be described. Fig.15 is a flowchart illustrating the processing procedure of checking settings. FIG. 16A to FIG. 16C An example of a UI for setting the color of a pre-printed image is illustrated.

[0121] In step S1501, the inspection process selection unit 202 sets the inspection items and their inspection levels for detecting defects in the printed image inspection on the UI 707. In step S1502, the inspection process selection unit 202 performs the setting of the inspection sheet. The setting of the inspection sheet indicates whether the inspection sheet is a preprinted sheet on which an image is preprinted. According to the present embodiment, by removing the preprinted image, the inspection in comparison with the reference image is realized without acquiring the information of the image printed on the preprinted sheet. On the UI 709, the user selects the radio button 708 indicating that the preprinted image is printed on the inspection sheet.

[0122] In step S1503, the inspection process selection unit 202 determines whether the inspection is an inspection of a preprinted sheet depending on whether the radio button 708 is selected on the UI 709. When it is determined that the inspection is an inspection of a preprinted sheet, the flow proceeds to step S1504. When it is determined that the inspection is not an inspection of a preprinted sheet, the process ends.

[0123] In step S1504, the inspection process selection unit 202 displays Fig.16A The image processing apparatus 100 is provided with a UI 1600 to scan the pre-printed sheet by the image scanning device 105. Then, the pre-printed sheet set in the sheet feeding unit 191 is conveyed to the image processing apparatus 100 without any printing while the pre-printed sheet is conveyed along the sheet conveying path 192. The image scanning device (scanner) 105 scans one side or both sides of the printed product conveyed from the printing device 190 on the sheet conveying path 110, thereby acquiring a pre-printed image.

[0124] In step S1505, the checking process selection unit 202 receives the color of the pre-printed image from the user. Fig. 16B The image data 1601 scanned by the image scanning device 105 is displayed on the UI 1600 (display control). Fig. 16C As shown in , a position selected by a user from image data 1601 is displayed as a designated color and the designated color is acquired.

[0125] In step S1506, the inspection process selection unit 202 calculates a three-dimensional LUT that can be used to remove the accepted designated color component. The processing procedure of the inspection setting according to the present embodiment has been described above.

[0126] Advantages of the present invention

[0127] According to the present embodiment, by scanning in advance a preprint sheet on which a preprint image is printed in advance and specifying the color of the preprint image from the scanned image, the user is enabled not to select a wrong color as the color of the preprint image.

[0128] Third embodiment

[0129] According to the second embodiment, a method of scanning a preprinted sheet on which a preprinted image is preprinted and manually specifying the color of the preprinted image from the scanned image is described. According to the third embodiment, a method of automatically acquiring the color of the preprinted image will be described.

[0130] According to the present embodiment, user convenience is improved by pre-scanning a pre-printed sheet on which a pre-printed image is pre-printed and determining and specifying the color of the pre-printed image from the scanned image. Hereinafter, only differences from the first embodiment will be described in detail.

[0131] Check setting processing

[0132] Next, we will refer to Fig.17 The processing procedure of checking settings in S302 according to the present embodiment is described. Fig.17 is a flowchart illustrating the processing procedure of checking settings.

[0133] In step S1701, the inspection process selection unit 202 sets the inspection items and the detection levels thereof for detecting defects in the print image inspection on the UI 707. In step S1702, the inspection process selection unit 202 performs setting of the inspection sheet.

[0134] In step S1703, the inspection process selection unit 202 determines whether the inspection is an inspection of a preprinted sheet depending on whether the radio button 708 is selected on the UI 709. When it is determined that the inspection is an inspection of a preprinted sheet, the flow proceeds to step S1704. When it is determined that the inspection is not an inspection of a preprinted sheet, the process ends.

[0135] In step S1704, the printing device 190 conveys the pre-printed sheet set in the sheet feeding unit 191 to the image processing device 100 without performing any printing while conveying the pre-printed sheet along the sheet conveying path 192. The image scanning device (scanner) 105 scans one side or both sides of the printed product conveyed from the printing device 190 on the sheet conveying path 110, thereby acquiring a pre-printed image.

[0136] In step S1705, the inspection process selection unit 202 determines the color of the pre-printed image. The acquired pre-printed image is subjected to a binarization process in which a predetermined brightness is set as a threshold value to generate a binary image. In the binarization process, pixels lower than a predetermined brightness are replaced with black pixels representing foreground pixels, and pixels equal to or higher than a predetermined brightness are replaced with white pixels representing background pixels. It should be noted that the technology used for the image binarization process may be a prior art as long as pixels can be converted into two levels of white and black according to the technology.

[0137] Then, the pixel values ​​of pixels in the acquired pre-printed image corresponding to the pixel positions determined to be black pixels in the image after binarization are registered as the designated colors of the pre-printed image.

[0138] In step S1706 , the inspection process selection unit 202 calculates a three-dimensional LUT that can be used to remove the accepted designated color component.

[0139] The processing procedure of the check setting according to the present embodiment has been described above.

[0140] Advantages of this image processing

[0141] According to the present embodiment, by pre-scanning a pre-printed sheet on which a pre-printed image is pre-printed to determine the color of the pre-printed image from the scanned image, the user is enabled not to select a wrong color as the color of the pre-printed image.

[0142] According to the present invention, by removing a specific color included in image data, an image printed on a pre-printed sheet on which information of the specific color is printed in advance can be correctly inspected.

[0143] Other embodiments

[0144] The embodiments of the present invention may also be implemented by providing software (program) for performing the functions of the above-described embodiments to a system or device via a network or various storage media, and a computer or a central processing unit (CPU) or a microprocessing unit (MPU) of the system or device reads and executes the program.

[0145] While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.The following claims are to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.

Claims

1. An inspection device, comprising: one or more controllers, the one or more controllers comprising one or more processors and one or more memories, The one or more controllers are configured to: Printing the inspection image on a pre-printed sheet on which information of a specific color is pre-printed; scanning the pre-printed sheet on which the inspection image is printed; removing the specific color included in the scanned image obtained by scanning; as well as Based on the reference image, the scanned image acquired after the specific color is removed is checked.

2. The inspection device according to claim 1, wherein: The reference image is generated according to the inspection image.

3. The inspection device according to claim 1, wherein: The specific color is set via the user interface.

4. The inspection device according to claim 1, wherein: The specific color includes a plurality of colors set via a user interface.

5. The inspection device according to claim 1, wherein the one or more controllers are further configured to: causing a display unit to display the scanned image acquired when scanning the preprinted sheet, in, The specific color is set via a user interface according to the image displayed on the display unit.

6. The inspection device according to claim 1, wherein the one or more controllers are further configured to: acquiring a color of the scanned image acquired when scanning the pre-printed sheet, in, The specific color is an acquired color.

7. The inspection device according to claim 1, wherein: The one or more controllers check whether there is a defect in the image acquired after removing the specific color based on a comparison result between the reference image and the image acquired after removing the specific color.

8. The inspection device according to claim 1, wherein: The reference image is an image corresponding to an image printed on the preprinted sheet that does not include the information of the specific color.

9. A control method for an inspection device, the control method comprising: a printing step for printing the inspection image on a pre-printed sheet on which information of a specific color is pre-printed; a scanning step for scanning the pre-printed sheet on which the inspection image is pre-printed; a removing step for removing the specific color included in the scanned image scanned and acquired in the scanning step; as well as A checking step for checking, based on a reference image, an image acquired after the specific color is removed in the removing step.

10. The control method of the inspection device according to claim 9, wherein: The reference image is generated according to the inspection image.

11. The control method of the inspection device according to claim 9, wherein: The specific color is set via the user interface.

12. The control method of the inspection device according to claim 9, wherein: The specific color includes a plurality of colors set via a user interface.

13. The control method of the inspection device according to claim 9, further comprising: a display control step for performing display control so that a display unit displays the scanned image acquired when the pre-printed sheet is scanned in the scanning step, Wherein, the specific color is set via a user interface according to the image displayed on the display unit.

14. The control method of the inspection device according to claim 9, further comprising: an acquisition step for acquiring the color of the scanned image acquired when the pre-printed sheet is scanned in the scanning step, The specific color is the color obtained in the obtaining step.

15. The control method of the inspection device according to claim 9, wherein: In the inspection step, based on a comparison result between the reference image and the image acquired after the specific color is removed, it is inspected whether there is a defect in the image acquired after the specific color is removed.

16. The control method of the inspection device according to claim 9, wherein: The reference image is an image corresponding to an image printed on the preprinted sheet that does not include the information of the specific color.

17. An inspection system, comprising: one or more controllers, the one or more controllers comprising one or more processors and one or more memories, The one or more controllers are configured to: Printing the inspection image on a pre-printed sheet on which information of a specific color is pre-printed; scanning the pre-printed sheet on which the inspection image is pre-printed; removing the specific color included in the scanned and acquired scanned image; as well as Based on the reference image, the scanned image acquired after the specific color is removed is checked.

Images