JP2004309220A - Apparatus and method for inspecting printed matter - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an apparatus for inspecting a printed matter, which can detect print abnormality corresponding to a specific color component and minimize the occurrence of defective prints, with out interrupting regular print works. <P>SOLUTION: In the apparatus, the print abnormality corresponding to the color component is detected. A printed surface of the printed matter on which a color image is printed, is photographed, thereby obtaining color images of R, G and B. The obtained color images of R, G and B are separated into images of color components C, M and Y used for printing the printed matter, and gray values of grayscale images composed of respective color components are analyzed at a plurality of regions respectively, and each analyzed result is comprehensively judged, thereby determining the print abnormality corresponding to the specific color component used for printing. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention is directed to a color printing apparatus that prints a color face image or the like on an ID card such as an automobile driver's license or an identification card, for example, a printed matter inspection apparatus that inspects a printed state of a printed matter on which a color image is printed, It relates to a printed matter inspection method.
[0002]
[Prior art]
As this type of printed matter inspection method, a color density level obtained from a color density standard sample or the like is set as a normal level, and the color density level of the color density standard sample to be inspected is compared with the normal level. Is known as a blank area, and print quality is determined based on an area ratio between the calculated blank area and a measurement target area (for example, see Patent Document 1).
[0003]
[Patent Document 1]
JP-A-4-145770
[Problems to be solved by the invention]
In the above-described conventional technology, in a color ribbon or a color image print using color ink, when inspecting print abnormalities of the print, a color density standard sample or the like is printed, and a color image obtained by imaging the sample target is obtained. The color density level of the image is compared with a predetermined level to determine a printing abnormality such as a missing color.
[0005]
However, when printing a color density standard sample, it is necessary to interrupt the normal printing operation and perform an inspection operation. With such an inspection method, it is impossible to immediately cope with a printing abnormality that occurs during a normal printing operation, and there is a possibility that a large number of printing defects will occur.
[0006]
Therefore, the present invention provides a printed matter inspection apparatus and a printed matter inspection method capable of detecting a printing abnormality for a specific color component without interrupting a normal printing operation and minimizing the occurrence of printing defects. With the goal.
[0007]
[Means for Solving the Problems]
The printed matter inspection apparatus according to the present invention is configured such that an image capturing unit that captures the color image from a printed material as a test object on which a color image is printed, and a color image captured by the image capturing unit is used for printing the printed material. Image converting means for decomposing each color component and converting the image into a grayscale image of each color component; density analyzing means for analyzing the density value of the grayscale image of each color component converted by the image converting means; A determination unit configured to determine a printing abnormality for a specific color component used for printing the printed matter based on an analysis result of the density analysis unit.
[0008]
Further, the printed matter inspection method of the present invention includes an image capturing step of capturing the color image from a printed material as a test object on which a color image is printed, and a color image captured by the image capturing step for printing the printed material. An image conversion step of decomposing for each used color component and converting to a grayscale image of each color component, and a density analysis step of analyzing the density value of the grayscale image of each color component converted by the image conversion step. A determination step of determining a printing abnormality for a specific color component used for printing the printed matter based on the analysis result of the density analysis step.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 schematically shows a configuration of a printed matter inspection apparatus according to an embodiment of the present invention. In FIG. 1, for example, a color image such as a face image of a card owner is printed on a printed material 11 such as an ID card on which a color image is printed as an inspection object. The printed material 11 is, for example, a C (cyan), M (magenta), and Y (yellow) ink ribbon used for general color printing, which is printed by a printing method such as thermal transfer printing using a thermal head.
[0010]
The ink ribbon is not limited to the C, M, and Y color components, and may be composed of other color components such as C (cyan), M (magenta), Y (yellow), and K (black). I do not care. Also, various color printing methods such as an ink jet method can be used as the printing method.
[0011]
The color image capturing unit 12 as an image capturing unit photoelectrically converts the color image on the printed matter 11 by optical scanning, and captures the color image as R (red), G (green), and B (blue) color images. . For example, the color image capturing unit 12 may perform image scanning using an area sensor such as a television camera, or may perform optical scanning by transporting the sensor side or the printed material side using a line sensor. Conceivable.
[0012]
The CMY image conversion unit 13 serving as an image conversion unit converts the R, G, and B color images captured by the color image capturing unit 12 into the color components used for printing the printed matter 11, ie, C, M, and Y in this example. The color components are separated into color components and converted into light and shade images of each color component.
[0013]
The CMY image storage unit 14 serving as an image storage unit stores the grayscale images of the respective color components separated by the CMY image conversion unit 13.
An image density analysis unit 15 as a density analysis unit analyzes the gray value of a gray image of each color component stored in the CMY image storage unit 14 for each arbitrary region.
[0014]
The comprehensive determination unit 16 as a determination unit comprehensively determines the analysis result of the image density analysis unit 15, determines a printing abnormality for a specific color component used for printing, and outputs the determination result. The control unit 17 as a control unit controls the operation of each of these units as a whole.
[0015]
Next, the flow of the printed matter inspection process in the above configuration will be described with reference to the flowchart shown in FIG.
The color image on the printed material 11 is photoelectrically converted in the color image capturing unit 12 and quantized as, for example, R, G, and B color images, which are the three primary colors, and each of the values is changed from “0” to “255”. The image is converted into a grayscale image having the image (step S1). It is needless to say that the gray value of the color image is not limited to a value from “0” to “255”.
[0016]
Next, the CMY image conversion unit 13 converts the R, G, and B color images obtained from the color image capturing unit 12 into C, M, and Y color components (step S2). For example, the image of each color component is stored as a grayscale image having a value of “0” to “255”.
Here, the conversion from the R, G, B color image to the C, M, Y grayscale image is performed using the following formula as a simple method since they have complementary color relationships. The conversion formula is not limited to this formula.
C = 255-R
M = 255-G
Y = 255-B
[0017]
Next, the image density analysis unit 15 measures, for example, the average density of each of the grayscale images of M and Y. In this case, the simplest method is to find the average density over the entire image, but in that case, the following problem occurs.
As shown in FIG. 3, printing is usually performed line by line in the main scanning direction by a thermal head, for example, and the thermal head or printed material 11 is conveyed in the sub scanning direction. In this case, if any printing abnormality such as an abnormality in the thermal head occurs during printing, as shown in FIG. 4, the normally printed area 11a and the area 11b in which the printing abnormality has occurred are mixed.
[0018]
When the average density is obtained for the entire image as described above, the printing error in the latter half may not be detected due to the large influence of the normally printed area 11a. Assuming the printing scan as shown in FIG. 3, the abnormal printing area 11b is separated from the normal printing area 11a in the printing sub-scanning direction as shown in FIG.
[0019]
Therefore, in the present embodiment, as shown in FIG. 5, the image density analysis unit 15 divides the image into, for example, a plurality of areas E1 to E4 in the printing sub-scanning direction (step S3), and The average density is measured for each E4 (step S4).
[0020]
Next, the comprehensive determination unit 16 compares each average density measured for each of the regions E1 to E4 divided by the image density analysis unit 15 with, for example, a predetermined threshold value set in advance. When the following color components are present, it is determined that the printing of the color components in that area is abnormal (steps S5 and S6).
[0021]
That is, the comprehensive determination unit 16 comprehensively determines a printing abnormality by performing a determination process according to, for example, a flowchart shown in FIG. 6, and outputs the determination result (step S7). Hereinafter, the flowchart of FIG. 6 will be described.
[0022]
First, in step S11, the average density of the area E1 is compared with a threshold, and if the average density is equal to or greater than the threshold, the process proceeds to step S12. In step S12, the average density of the area E2 is compared with a threshold, and if the average density is equal to or more than the threshold, the process proceeds to step S13. In step S13, the average density of the area E3 is compared with a threshold, and if the average density is equal to or more than the threshold, the process proceeds to step S14.
[0023]
In step S14, the average density of the area E4 is compared with a threshold value, and if the average density is equal to or greater than the threshold value, it is determined that the printed matter 11 is normal. In steps S11 to S14, if the average density is smaller than the threshold value even in one area, the printed matter 11 is determined to be abnormal.
[0024]
If such a determination is made, for example, as shown in FIG. 7, if the area E1 and the area E2 are normal in printing, the area E3 is partially printing abnormal, and the area E4 is full surface printing abnormal, the area E1 In the area E2, no printing abnormality is recognized, and in the case of the area E3, no printing abnormality may be recognized. However, in the area E4, the printing abnormality can be reliably detected.
[0025]
In the above description, the number of regions to be divided is four for convenience, but it is needless to say that the number is not limited to four. Although the average density is used as a value for evaluating the density of the grayscale image, another density evaluation value may be used.
[0026]
Further, for example, as shown in FIG. 8, a plurality of areas E1 to E4 for performing the density analysis are formed in a plurality of areas E1-1 to E1-4, E2-1 to E2-4, and E3- in the main scanning direction. By dividing the data into E1 to E3-4 and E4-1 to E4-4, it is possible to detect a printing abnormality with higher accuracy. The determination process of the comprehensive determination unit 16 in that case is, for example, a flowchart as shown in FIG. Hereinafter, the flowchart of FIG. 9 will be described.
[0027]
First, in step S21, the average density of the area E1-1 is compared with a threshold, and if the average density is less than the threshold, the process proceeds to step S22. In step S22, the average density of the area E1-2 is compared with a threshold, and if the average density is less than the threshold, the process proceeds to step S23. In step S23, the average density of the area E1-3 is compared with a threshold value, and if the average density is less than the threshold value, the process proceeds to step S24. In step S24, the average density of the area E1-4 is compared with a threshold value, and if the average density is less than the threshold value, the printed matter 11 is determined to be abnormal printing.
[0028]
If it is determined in steps S21 to S24 that the average density is equal to or larger than the threshold value even in one region, the process proceeds to step S25. In step S25, the average density of the area E2-1 is compared with the threshold, and if the average density is less than the threshold, the process proceeds to step S26. In step S26, the average density of the area E2-2 is compared with the threshold, and if the average density is less than the threshold, the process proceeds to step S27.
[0029]
In step S27, the average density of the area E2-3 is compared with the threshold, and if the average density is less than the threshold, the process proceeds to step S28. In step S28, the average density of the area E2-4 is compared with a threshold value, and if the average density is less than the threshold value, the printed matter 11 is determined to be abnormal.
[0030]
If it is determined in steps S25 to S28 that the average density is equal to or larger than the threshold value even in one area, the process proceeds to step S29. In step S29, the average density of the area E3-1 is compared with the threshold, and if the average density is less than the threshold, the process proceeds to step S30. In step S30, the average density of the area E3-2 is compared with the threshold, and if the average density is less than the threshold, the process proceeds to step S31.
[0031]
In step S31, the average density of the area E3-3 is compared with a threshold, and if the average density is less than the threshold, the process proceeds to step S32. In step S32, the average density of the area E3-4 is compared with a threshold value, and if the average density is less than the threshold value, the printed matter 11 is determined to be abnormal.
[0032]
If it is determined in steps S29 to S32 that the average density is equal to or greater than the threshold value even in one area, the process proceeds to step S33. In step S33, the average density of the area E4-1 is compared with a threshold, and if the average density is less than the threshold, the process proceeds to step S34. In step S34, the average density of the area E4-2 is compared with the threshold, and if the average density is less than the threshold, the process proceeds to step S35.
[0033]
In step S35, the average density of the area E4-3 is compared with a threshold, and if the average density is less than the threshold, the process proceeds to step S36. In step S36, the average density of the area E4-4 is compared with a threshold value, and if the average density is less than the threshold value, the printed matter 11 is determined to be abnormal printing.
In steps S33 to S36, if the average density is equal to or greater than the threshold value even in one area, the printed matter 11 is determined to be normal.
[0034]
As described above, according to the above-described embodiment, R, G, and B color images are acquired by imaging the print surface of a printed matter on which a color image is printed, and the acquired R, G, and B color images are acquired. The image is decomposed for each of the C, M, and Y color components used for printing the printed matter, and the grayscale value of the grayscale image in each color component is analyzed for each of a plurality of regions. By making the determination, it is possible to detect a printing abnormality for a specific color component without interrupting a normal printing operation, and to minimize the occurrence of a printing failure medium.
[0035]
【The invention's effect】
As described above in detail, according to the present invention, a printed matter inspection apparatus and a printed matter that can detect a printing abnormality for a specific color component and minimize the occurrence of a printing failure without interrupting a normal printing operation An inspection method can be provided.
[Brief description of the drawings]
FIG. 1 is a block diagram schematically showing a configuration of a printed matter inspection apparatus according to an embodiment of the present invention.
FIG. 2 is a flowchart illustrating a flow of a printed matter inspection process.
FIG. 3 is a diagram illustrating a print scanning direction for a printed material.
FIG. 4 is a view for explaining printing failure of a printed material.
FIG. 5 is a view for explaining division of a region for performing density analysis.
FIG. 6 is a flowchart illustrating a determination process of a comprehensive determination unit.
FIG. 7 is a diagram for describing determination of a printing abnormality.
FIG. 8 is a view for explaining another example of the division of the area for performing the density analysis.
FIG. 9 is a flowchart illustrating another example of the determination process of the comprehensive determination unit.
[Explanation of symbols]
11: printed matter (inspection object), 12: color image pickup unit (image pickup unit), 13: CMY image conversion unit (image conversion unit), 14: CMY image storage unit (image storage unit), 15: image density analysis Section (concentration analysis means), 16: comprehensive determination section (determination means), 17: control section (control means).

Claims (11)

Image capturing means for capturing the color image from a printed material as a test object on which a color image is printed,
Image conversion means for decomposing a color image captured by the image capturing means for each color component used for printing the printed matter, and converting the color image into a shaded image of each color component;
Density analysis means for analyzing the density value of the grayscale image in each color component converted by the image conversion means,
Determining means for determining a printing abnormality for a specific color component used for printing the printed matter based on an analysis result of the density analyzing means;
A printed matter inspection apparatus comprising: 2. The printed matter inspection apparatus according to claim 1, wherein the analysis of the density value of the grayscale image performed by the density analysis means is to obtain an average density of the grayscale image. The density analysis unit divides a printing surface on which a color image of the printed matter exists into a plurality of regions in a printing sub-scanning direction when printing the printed material, and converts the divided plurality of regions by the image conversion unit. 2. The printed matter inspection apparatus according to claim 1, wherein a density value of the grayscale image for each of the color components is analyzed. The determination unit evaluates the analysis result of the density analysis unit for each of the plurality of divided areas, and determines that the print is abnormal when one or more areas are evaluated as abnormal. The printed matter inspection apparatus according to claim 3, wherein: The density analysis unit further divides a plurality of areas obtained by dividing a printing surface on which a color image of the printed matter is present in a printing sub-scanning direction when printing the printed matter into a plurality of areas in a printing main scanning direction. 4. The density value of a grayscale image in each color component converted by the image conversion unit for each divided region in the printing main scanning direction and each divided region in the printing sub-scanning direction. Print inspection equipment. The determination unit evaluates the analysis result of the density analysis unit for each of the divided regions in the printing main scanning direction and each of the regions in the printing sub-scanning direction, and evaluates a printing abnormality in all regions in the same printing main scanning direction. Is determined as abnormal printing, the area in the main scanning direction row is determined to be abnormal printing, and if one or more main scanning direction rows are evaluated as abnormal printing in the sub-scanning direction, it is determined to be abnormal printing for the printed matter. The printed matter inspection apparatus according to claim 3, wherein the inspection is performed. The color image obtained by imaging the printed matter by the image imaging means is an R (red), G (green), B (blue) color image. 2. An image according to claim 1, wherein the image is separated into C (cyan), M (magenta), Y (yellow) or C (cyan), M (magenta), Y (yellow), and K (black) color components. The printed matter inspection device according to the above. The image processing apparatus further includes an image storage unit that stores a grayscale image of each color component converted by the image conversion unit, wherein the density analysis unit analyzes a density value of the grayscale image stored in the image storage unit. The printed matter inspection apparatus according to claim 1, wherein An image capturing step of capturing the color image from a printed material as a test object on which a color image is printed,
An image conversion step of decomposing the color image captured by the image capturing step for each color component used for printing the printed matter, and converting the color image into a grayscale image of each color component;
A density analysis step of analyzing a density value of a grayscale image in each color component converted by the image conversion step;
A determination step of determining a printing abnormality for a specific color component used for printing the printed matter based on the analysis result of the density analysis step;
A printed matter inspection method, comprising: The density analysis step divides a printing surface on which a color image of the printed matter is present into a plurality of regions in a printing sub-scanning direction when printing the printed material, and converts the divided plurality of regions by the image conversion step. 10. The printed matter inspection method according to claim 9, wherein a density value of the grayscale image for each of the color components is analyzed. The density analysis step further divides a plurality of areas obtained by dividing a printing surface on which a color image of the printed matter is present in a printing sub-scanning direction when printing the printed matter into a plurality of areas in a printing main scanning direction. 10. The density value of a grayscale image of each color component converted in the image conversion step is analyzed for each of the divided areas in the printing main scanning direction and each area in the printing sub-scanning direction. Printed matter inspection method.

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