JP2017211207A - Method of detecting contamination of goods - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enhance the accuracy of detecting external contamination of goods.SOLUTION: A method of detecting external contamination of goods having a printed part colored differently from the color of the goods, includes step S1 of acquiring image data on the exterior of the goods, step S2 of identifying a first area, which is an area including the printed part by processing image data, and step S3 of detecting contamination by conducting image processing only on a second area, which is the area excluding the first area from the image data. Step S2 of identifying the first area includes a pre-step S21 of extracting the contour edge of the printed part by image processing and a post-step S22 of defining the first area on the basis of the contour edge.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a method for detecting fouling of the outer surface of an article.

  2. Description of the Related Art Conventionally, a method for inspecting the outer surface of an article for contamination or scratches based on image data obtained by imaging the outer surface of the article including a tire or the like has been proposed (for example, see Patent Document 1 below). In this type of inspection method, a portion where the brightness of the image data is greater than a predetermined allowable value is detected as contamination or scratches. This allowable value is set based on, for example, the color of a normal article that is not soiled or scratched.

JP 2014-238292 A

  For example, a printing unit such as an identification code may be provided on the outer surface of the article. For example, the printed portion is colored and printed using a paint having a color different from the color of the article. When such an article is inspected, there has been a problem in the image data that the brightness of the printing portion is larger than an allowable value, and the printing portion is erroneously detected as a contaminated portion.

  The present invention has been devised in view of the actual situation as described above, and has as its main purpose to provide a method capable of improving the accuracy of detecting the contamination of the outer surface of an article.

  The present invention is a method for detecting a stain on the outer surface of an article, wherein the article has a printed portion colored on the outer surface in a color different from the color of the article, and the printed portion is Including at least one of characters or symbols having a predetermined print area size, and the method includes obtaining the image data of the outer surface of the article, and processing the image data to Including a step of specifying a first region that is a region to include, and a step of detecting the stain by performing image processing only on a second region that is a region obtained by removing the first region from the image data. The step of specifying the first region includes a pre-step of extracting a contour edge of the printing unit by image processing, and a post-step of defining the first region based on the contour edge. The features.

  In the method for detecting fouling of an article according to the present invention, it is preferable that the post-process defines an area surrounded by the contour edge as the first area.

  In the method for detecting fouling of an article according to the present invention, it is preferable that the post-process defines a rectangular area circumscribing the contour edge as the first area.

  In the method for detecting fouling of an article according to the present invention, it is preferable that the post-process defines the first region as a region larger than a rectangular region circumscribing the contour edge.

  In the method for detecting contamination of an article according to the present invention, it is preferable that the post-process includes a step of defining the rectangular region and a step of enlarging the rectangular region and defining the first region.

  In the method for detecting fouling of an article according to the present invention, the post-process includes calculating the position of the center of gravity of the area surrounded by the contour edge, the position of the center of gravity, and the print area size. And defining a region.

  In the method for detecting contamination of an article according to the present invention, the post-process is based on a step of calculating a center position of a rectangular area circumscribing the contour edge, the position of the center, and the print area size. And defining the first region.

  In the method for detecting fouling of an article according to the present invention, the printing unit includes a plurality of printing elements including the characters or the symbols, and the step of specifying the first area is performed by processing the image data. Preferably, the method includes a step of specifying an aggregate of pixels indicating an element and a step of identifying the aggregate as the print element when the number of the aggregate is the same as the number of the print elements.

  In the method for detecting fouling of an article according to the present invention, the article may be a tire.

  The method for detecting fouling of an article of the present invention includes a step of identifying a first area, which is an area including a printing unit, by processing image data of an outer surface of the article, and an area obtained by removing the first area from the image data. And a step of detecting fouling by performing image processing only on the second region. Thereby, the contamination detection method for an article according to the present invention can prevent erroneous detection of the printing unit as contamination, and thus can improve the detection accuracy of contamination.

  The step of specifying the first region includes a pre-step of extracting the contour edge of the printing unit by image processing and a post-step of defining as the first region based on the contour edge. Thereby, the stain detection method for an article of the present invention can accurately identify the first region for each print unit even when the sizes of the print units are different from each other. .

It is a conceptual diagram which shows an example of the test | inspection apparatus used with the stain | pollution | contamination detection method of this embodiment. It is a fragmentary perspective view of the tire shown in FIG. It is a flowchart which shows an example of the process sequence of the stain | pollution | contamination detection method of this embodiment. It is a top view which illustrates a part of image data. It is a flowchart explaining an example of the process sequence of the specific process of this embodiment. It is a flowchart which shows an example of the process sequence of the front process of this embodiment. FIG. 4 is a diagram partially showing image data that has been binarized. It is a flowchart which shows an example of the process sequence of the detection process of this embodiment. It is a figure which shows the image data in which the 2nd area | region was set. FIG. 10 is a diagram illustrating image data obtained by binarizing FIG. 9. It is a flowchart explaining the process sequence of the specific process of other embodiment of this invention. It is a figure which shows partially the image data by which the binarization process was carried out. It is a figure which shows the image data in which the 2nd area | region was set. It is a top view which illustrates a part of image data. FIG. 14 is a view partially showing the binarized image data. It is a flowchart which shows an example of the process sequence of the specific process of further another embodiment of this invention. It is a flowchart which shows an example of the process sequence of the post process of further another embodiment of this invention. It is a figure which shows the image data in which the rectangular area was defined. It is a figure which shows the image data in which the 1st area | region was defined. It is a figure which shows the image data in which the 2nd area | region was set. It is a flowchart which shows an example of the process sequence of the post process of further another embodiment of this invention. It is a figure which shows partially the image data by which the binarization process was carried out. It is a figure which shows the image data in which the 1st area | region was defined. It is a flowchart which shows an example of the process sequence of the post process of further another embodiment of this invention. It is a figure which shows partially the image data by which the binarization process was carried out. It is a figure which shows the image data in which the 1st area | region was defined.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
The method for detecting fouling of an article according to this embodiment (hereinafter, simply referred to as “fouling detection method”) is a method for detecting fouling attached to the outer surface of an article to be inspected (before shipment in this embodiment). It is. In the present embodiment, the article is exemplified by the tire 1. FIG. 1 is a conceptual diagram showing an example of an inspection apparatus used in the contamination detection method of the present embodiment. FIG. 2 is a partial perspective view of the tire shown in FIG.

  As shown in FIG. 2, the outer surface 2 o of the tire 1 of the present embodiment has a printing unit 3 that is colored with a color different from the color of the tire 1. The printing unit 3 of the present embodiment is brighter than the color of the tire 1 (black in the present embodiment) on the outer surface of the tread portion 2 (a tread grounding surface that is in contact with the road surface (not shown) in the present embodiment) 2o. Colored and printed by a color (for example, white) paint.

  The printing unit 3 of the present embodiment is configured as an identification code such as a tire size, for example. The printing unit 3 is configured to include at least one printing element 3a of a character or a symbol having a printing area size 4 (indicated by a two-dot chain line in the figure) determined in advance. It is constituted by the element 3a. The print area size 4 of the present embodiment is set to a rectangular shape in plan view, and indicates the size of the maximum range to which the print element 3a is attached. Further, the printing elements 3a of the present embodiment are spaced at regular intervals in the tire circumferential direction.

  As shown in FIG. 1, the detection device 5 of this embodiment includes a tire support means 6, an imaging means 7, and a control means 8.

  The tire support means 6 is for rotatably supporting the tire 1. The tire support means 6 includes a turntable 11 and a drive means 12. On the turntable 11, the sidewall portion 2s of the tire 1 is placed. The turntable 11 is provided with a shaft 13 extending along the tire axial direction. The driving means 12 is configured as a motor for rotating the shaft 13 of the turntable 11. The turntable 11 is rotated around the vertical axis by driving of the driving means 12. Thereby, the tire 1 placed on the turntable 11 is rotated in the tire circumferential direction.

  The imaging means 7 is for capturing an image of the outer surface 2o of the tire 1 and acquiring image data. As the imaging unit 7, for example, a camera or a video camera that can shoot a still image or a moving image can be employed.

  The imaging means 7 of the present embodiment is disposed on the outer side in the tire radial direction of the tread portion 2 of the tire 1. The imaging unit 7 can continuously photograph the outer surface 2o of the tread portion 2 in the tire circumferential direction by rotating the tire 1 in the tire circumferential direction by the turntable 11. In imaging, for example, it is desirable that the imaging portion of the tire 1 (in this embodiment, the outer surface 2o of the tread portion 2) is illuminated by the illumination unit 14, for example.

  The control means 8 controls the drive means 12 and the imaging means 7 of the tire support means 6 and also performs image processing on the image data of the outer surface 2o of the tire 1 to detect contamination (not shown) attached to the outer surface 2o. Is to do. Examples of the contamination include concave portions, contamination, and internal damage.

  The recess is, for example, a steep recess or scratch on the outer surface 2o of the tire 1. The dirt is, for example, a paint piece attached to the outer surface 2o of the tire 1, an anti-adhesive agent, or a cord material. The internal damage is, for example, a cord material that protrudes from the inside of the tire 1 to the outer surface 2o. These stains have a color different from the color of the outer surface 2o of the tire. For this reason, the stain is imaged with a brightness different from the brightness of the outer surface 2o of the tire 1 except for the printing unit 3.

  The control means 8 of this embodiment includes an input means 16, an output means 17, and a calculation means 18. The input unit 16 includes, for example, a keyboard that accepts input from the user, a mouse, and the like. The output unit 17 is configured by, for example, a monitor and / or a printer.

  The calculation means 18 includes a calculation unit 18a composed of a CPU (central processing unit), a storage unit 18b in which control procedures and programs are stored in advance, and a working memory 18c in which the control procedures are read from the storage unit 18b. It is configured.

  The calculation unit 18 a is connected to the drive unit 12 of the tire support unit 6. Thereby, the drive means 12 controls the rotation speed, rotation direction, and the like of the turntable 11 by transmitting a signal from the calculation unit 18a. Furthermore, the drive means 12 can transmit the position information and the like in the circumferential direction of the tire 1 placed on the turntable 11 to the calculation unit 18a.

  The calculation unit 18 a is connected to the imaging unit 7. Thereby, the imaging means 7 controls the timing of imaging. Furthermore, the imaging means 7 can transmit the image data of the outer surface 2o of the tire 1 to the calculation unit 18a.

  In the calculation unit 18a, image processing of the image data of the outer surface 2o of the tire 1 is performed based on the control procedure stored in the storage unit 18b. In the image processing, for example, the image data 21 (shown in FIG. 4) is binarized, and the contaminated part 9 is distinguished from the unstained part. By determining the presence or absence of the soiled portion 9, the soiled surface 9a of the outer surface 2o of the tire 1 is detected. A specific procedure of image processing according to the present embodiment will be described later.

  By the way, when the tire 1 having the printing unit 3 as described above is inspected, the calculation unit 18 cannot distinguish between the printing unit 3 and the stained portion 9 that are attached in a color different from the color of the tire 1. There is a possibility that the printing unit 3 may be erroneously detected as the contaminated portion 9.

  In order to prevent such erroneous detection and increase the detection accuracy of the contamination of the outer surface 2o of the tire 1, the contamination detection method of the present embodiment is a region including the printing unit 3 (printing element 3a) from the image data. The fouling 9a is detected only for the second region excluding one region. FIG. 3 is a flowchart illustrating an example of a processing procedure of the contamination detection method according to the present embodiment.

  In the fouling detection method of the present embodiment, first, image data of the outer surface 2o of the tire 1 is acquired (step S1). In step S1, first, as shown in FIG. 1, the calculation unit 18a transmits a signal to the drive means 12 of the tire support means 6 to cause the tire 1 placed on the turntable 11 to move in the tire circumferential direction. Rotate. Furthermore, in process S1, the calculating part 18a transmits a signal to the imaging means 7, and the outer surface 2o of the tire 1 (in this embodiment, the outer surface of the tread part 2) is imaged at a fixed interval. Thereby, in process S1, the image data of the outer surface 2o of the tire 1 is acquired over the whole region of a tire peripheral direction. FIG. 4 is a plan view illustrating a part of the image data 21. The image data 21 is input to the storage unit 18b or the work memory 18c.

  Next, in the contamination detection method of the present embodiment, the computing unit 18 processes the image data 21 to identify the first region T1 (shown in FIG. 7) that is the region including the printing unit 3 (specifying step). S2). The first region T <b> 1 of the present embodiment is specified for each printing element 3 a of the printing unit 3. FIG. 5 is a flowchart for explaining an example of the processing procedure of the specific step S2 of the present embodiment.

  In the specific step S2 of the present embodiment, first, the contour edge of the printing unit 3 is extracted (previous step S21). In the pre-process S21, the contour edge of each printing element 3a of the printing unit 3 is extracted by image processing of the image data 21 (shown in FIG. 4) by the computing means 18 (shown in FIG. 1). FIG. 6 is a flowchart illustrating an example of a processing procedure of the previous step S21 of the present embodiment.

  In the pre-process S21 of the present embodiment, first, the image data 21 (shown in FIG. 4) is binarized (process S211). In step S211, for a plurality of pixels (not shown) constituting the image data 21, if the luminance value is larger than a predetermined first threshold value, the luminance value is set to the first color value (in this embodiment, (White). On the other hand, in step S211, if the luminance value is equal to or less than the first threshold value, the luminance value is replaced with a second color value (black in this embodiment). FIG. 7 is a diagram partially showing image data 21 obtained by binarizing FIG.

  The first threshold is set based on, for example, the color (luminance) of the printing unit 3 (shown in FIG. 4). Thereby, in the binarized image data 21, the pixel indicating the printing unit 3 is displayed with the first color value (white in the present embodiment), and the stain spot 9 darker than the printing unit 3 and the tire 1 are displayed. A pixel indicating the outer surface 2o is displayed with a second color value (black in this embodiment).

  Next, in the previous step S21, the printing unit 3 is specified based on the binarized image data 21 (step S212). In step S212, the first color value (white in the present embodiment) pixel (not shown) aggregate (hereinafter simply referred to as “pixel group”) 24 is determined from a predetermined first area. The pixel group 24 having a larger area is specified as the printing element 3 a of the printing unit 3. Thereby, even if the pixel (not shown) indicating the stain 9a is replaced with the first color value, the stain 9a can be prevented from being recognized as the printing element 3a of the printing unit 3. About a 1st area, it sets suitably. Considering that the area of the pixel group 24 differs for each type of the printing element 3a, the first area is the area of the printing element 3a that has been normally printed (for example, the average value of the areas of all types of printing elements 3a). ) Is preferably set to 50% to 80%.

  As shown in FIG. 2, the printing elements 3a are spaced at a constant interval W1 in the tire circumferential direction. In the present embodiment, the area of the pixel group 24 of the first color value (white in the present embodiment) is larger than the first area and is constant in order to increase the specific accuracy of the printing element 3a. It is desirable that only the pixel group 24 separated by the interval W1 is specified as the print element 3a of the print unit 3.

  Further, when the number of print elements 3a (for example, four) is determined in advance, when the number of the aggregates (pixel group) 24 and the number of the print elements 3a are the same, the aggregate (pixels) The step of identifying the group 24 as the printing element 3a is preferably performed. Thereby, even if the pixel (not shown) indicating the stain 9a is replaced with the first color value, it is possible to effectively prevent the stain 9a from being recognized as the printing element 3a of the printing unit 3.

  Next, in the pre-process S21 of this embodiment, a contour edge is extracted based on the printing unit 3 specified from the image data 21 (process S213). In step S213, the coordinate values of the pixels arranged on the outline 24s of the pixel group 24 among the pixels (not shown) constituting the pixel group 24 specified as the printing element 3a of the printing unit 3 are specified. Thereby, in step S213, the contour edge 22 of each print element 3a can be extracted.

  Next, in specific process S2 of this embodiment, it defines as 1st area | region T1 based on the outline edge 22 of the printing element 3a of the printing part 3 (post-process S22). In the post-process S22 of the present embodiment, a region surrounded by the contour edge 22 of the printing element 3a of the printing unit 3 is defined as a first region T1. Thereby, in post-process S22 of this embodiment, only the area | region where the printing element 3a is arrange | positioned is defined as 1st area | region T1. The first area T1 is input to the storage unit 18b or the work memory 18c.

  Next, in the contamination detection method of the present embodiment, the contamination 9a is detected only for the second region T2 (shown in FIG. 9) that is a region obtained by removing the first regions T1 from the image data 21 (detection). Step S3). In the detection step S3 of the present embodiment, the calculating unit 18 performs image processing on the second region T2, thereby detecting the stain 9a. FIG. 8 is a flowchart illustrating an example of a processing procedure of the detection step S3 of the present embodiment.

  In the detection step S3 of the present embodiment, first, the second region T2 is specified (step S31). In step S31, each first region T1 is excluded from the image data 21 before binarization processing shown in FIG. 4 based on the coordinate value of each first region T1 (for example, the coordinate value of the contour edge 22). (Masked). Thus, the second region T2 is specified in the image data 21. FIG. 9 is a diagram showing image data in which the second region T2 is set.

  Next, in the detection step S3 of the present embodiment, the image data 21 is subjected to image processing (in this embodiment, binarization processing) only for the second region T2 (step S32). FIG. 10 shows image data 21 obtained by binarizing FIG. In step S32, if the luminance value is larger than a predetermined second threshold value for a plurality of pixels (not shown) constituting the second region T2, the luminance value is set to the first color value (in the present embodiment). , White). On the other hand, in step S32, if the luminance value is equal to or smaller than the second threshold value, the luminance value is replaced with a second color value (black in this embodiment).

  The second threshold is set in advance based on, for example, the color (luminance) of the contaminated portion 9 (shown in FIG. 9) that has occurred so far. Thereby, in the binarized image data 21, the pixel (not shown) indicating the stain 9a is displayed with the first color value (white in the present embodiment), and the outer surface 2o of the tire 1 darker than the stain 9a is displayed. The pixel shown is displayed with the second color value (in this embodiment, black). The first region T1 may also be displayed with the second color value (black in this embodiment).

  Next, in the detection step S3 of the present embodiment, contamination is detected based on the second region T2 that has been subjected to image processing (binarization processing in the present embodiment) (step S33). In step S33, a pixel group 30 (shown in FIG. 10) of pixels (not shown) having the first color value (white in the present embodiment) is detected as the contamination 9a. The coordinate value of the pixel group 30 detected as the contamination 9a is input to the storage unit 18b or the work memory 18c of the calculation unit 18.

  In the present embodiment, the contamination 9a of the outer surface 2o of the tire 1 is detected only for the second region T2 excluding the first region T1 (shown in FIG. 9) including the printing element 3a. It is possible to prevent erroneous detection as contamination 9a. Therefore, in the contamination detection method of this embodiment, the detection accuracy of the contamination 9a can be increased.

  As shown in FIG. 9, since the first region T1 of the present embodiment is configured only by the region where the printing element 3a is disposed, the outer surface 2o of the tire 1 excluding only the printing element 3a is defined as the second region. It can be specified as T2. For this reason, in the detection step S3 of the present embodiment, the contamination 9a is detected in the entire outer surface 2o of the tire 1 except for the printing element 3a, so that the detection accuracy of the contamination 9a is effectively increased. be able to.

  Next, in the contamination detection method of the present embodiment, the presence / absence of the contamination 9a on the outer surface 2o of the tire 1 is determined (step S4). In step S4, the calculation means 18 determines the presence or absence of the contamination 9a on the outer surface 2o of the tire 1 based on the presence or absence of the pixel group 30 (shown in FIG. 10) detected as the contamination 9a. In the present embodiment, the presence / absence of the contamination 9 a is determined by the inspector based on the inspection result displayed on the output unit 17, but may be automatically performed by the control unit 8.

  In Step S4, when it is determined that the outer surface 2o of the tire 1 is free from the fouling 9a (“No” in Step S4), the tire 1 is shipped (Step S5). On the other hand, when it is determined that the outer surface 2o of the tire 1 is contaminated 9a ("Yes" in step S4), the contaminated portion 9 attached to the outer surface of the tire 1 is removed (step S6). At this time, in step S6, it is desirable that the position of the contaminated portion 9 is displayed on the output unit 17 (shown in FIG. 1) on the output unit 17 (shown in FIG. 1). And after the stain | pollution | contamination location 9 is removed, the tire 1 is shipped (process S5). As described above, in the contamination detection method of the present embodiment, the detection accuracy of the contamination 9a can be increased, so that the tire 1 having the contamination 9a can be prevented from being shipped accidentally. In addition, when the stain | pollution | contamination location 9 cannot be removed, the shipment of the tire 1 is stopped.

  In the specific step S2 of the present embodiment, the mode in which the region surrounded by the contour edge 22 of the printing element 3a of the printing unit 3 is exemplified as the first region T1, but is not limited to such a mode. FIG. 11 is a flowchart for explaining the processing procedure of the specifying step S2 according to another embodiment of the present invention. In addition, in this embodiment, about the structure same as the previous embodiment, the same code | symbol may be attached | subjected and description may be abbreviate | omitted.

  In the post-process S23 of this embodiment, the rectangular area 26 circumscribing the contour edge 22 is defined as the first area T1. FIG. 12 is a diagram partially showing the binarized image data. The rectangular area 26 is in contact with the outermost end in the tire circumferential direction D1 of the printing element 3a and the outermost end in the tire axial direction D2. The rectangular area 26 is defined for each print element 3a.

FIG. 13 is a diagram illustrating image data in which the second area is set. Since the first region T1 of this embodiment is defined as a rectangular region 26 circumscribing the contour edge 22 of the printing element 3a shown in FIG. 12, the tire excludes only the rectangular region 26 (that is, the first region T1). One outer surface 2o can be specified as the second region T2. For this reason, in the detection step S3 of the present embodiment, the stain 9a is detected for all regions except the rectangular region 26 on the outer surface 2o of the tire 1, and therefore the printing element 3a is detected as the stain 9a. Can be prevented.
Thereby, in detection process S3 of this embodiment, the detection accuracy of dirt 9a of outer surface 2o of tire 1 can be raised certainly.

  In the specific process S2 of the previous embodiment, the aspect in which the rectangular area 26 circumscribing the contour edge 22 is defined as the first area T1 is exemplified, but the present invention is not limited to such an aspect. FIG. 14 is a plan view illustrating a part of the image data 21. In the example of FIG. 14, the printing element 3 a of the printing unit 3 has a poorly colored portion 3 w that is lightly colored or not colored. The luminance value of the pixel (not shown) indicating such a poorly colored portion 3w is set to a first threshold value (ie, in step S211 (shown in FIG. 6) in which the image data 21 (shown in FIG. 4) is binarized. In some cases, the value is equal to or lower than a threshold value set based on the color (luminance) of the printing unit 3 (shown in FIG. 4).

  FIG. 15 is a diagram partially showing the image data 21 in which FIG. 14 is binarized. When the image data 21 having the poorly colored portion 3w is binarized in the previous step S21, the pixels of the poorly colored portion 3w are in the second color similarly to the pixels indicating the fouled portion 9 and the outer surface 2o of the tire 1. It is displayed as a value (in this embodiment, black). Therefore, in the specific step S2 of the embodiments so far, it may not be possible to define the first region T1 (shown in FIG. 12) including the poorly colored portion 3w. In the detection step S3, the poorly colored portion 3w is contaminated. May be detected. For this reason, it is desirable to define the first region T1 including the poorly colored portion 3w so that the poorly colored portion 3w is not included in the second region T2 (shown in FIG. 13).

  FIG. 16 is a flowchart showing an example of the processing procedure of the specifying step S2 according to still another embodiment of the present invention. In addition, in this embodiment, about the structure same as the previous embodiment, the same code | symbol may be attached | subjected and description may be abbreviate | omitted.

  In the post-process S24 of this embodiment, the first region T1 is defined as a region larger than the rectangular region circumscribing the contour edge 22. FIG. 17 is a flowchart showing an example of the processing procedure of the post-process S24 of still another embodiment of the present invention. FIG. 18 is a diagram showing the image data 21 in which the rectangular area 26 is defined.

  In the post-process S24 of the present embodiment, first, a rectangular area 26 circumscribing the contour edge 22 is defined (process S241). The rectangular area 26 is in contact with the outermost end in the tire circumferential direction D1 and the outermost end in the tire axial direction D2 of the printing element 3a shown in FIG. The rectangular area 26 is defined for each print element 3a.

  Next, in the post-process S24 of the present embodiment, the first area T1 is defined by enlarging the rectangular area 26 (process S242). FIG. 19 is a diagram showing the image data 21 in which the first region T1 is defined.

  In step S242 of the present embodiment, each rectangular region 26 is enlarged by a predetermined first length L1 on both sides in the tire circumferential direction D1 and on both sides in the tire axial direction D2. Thereby, in step S242, even if the rectangular area 26 smaller than the normally printed printing element 3a is defined, the first area T1 including the entire printing element 3a (that is, including the poorly colored portion 3w) is defined. can do.

  About 1st length L1, it can set suitably according to the specific precision etc. of the printing element 3a. In order to define the first region T1 that completely includes the print element 3a, the first length L1 is 0.2 times to 0. 0 to the length L4 of one side of the print region size 4 (shown in FIG. 2). It is desirable to set 8 times. If the first length L1 is less than 0.2 times the length L4 of one side, the first region T1 including the entire print element 3a (that is, including the poorly colored portion 3w) cannot be defined. There is a fear. Conversely, when the first length L1 exceeds 0.8 times the length L4 of one side, the second region (that is, the first region from the image data 21) to be detected for the contamination 9a (shown in FIG. 4). The area excluding T1) may be small, and the detection accuracy of the stain 9a may be reduced. From such a viewpoint, the first length L1 is preferably not less than 0.3 times the length L4 of one side and preferably not more than 0.7 times.

  Moreover, although the aspect expanded by the same 1st length L1 was illustrated in the tire circumferential direction both sides and the tire axial direction both sides in this embodiment, it is not necessarily limited to such an aspect. For example, the lengths to be enlarged may be different based on the aspect ratio of the print area size 4 or the like.

  FIG. 20 is a diagram illustrating image data in which the second area is set. Since the first region T1 of this embodiment is defined as a region larger than the rectangular region 26 circumscribing the contour edge 22 of the printing element 3a shown in FIG. 19, the entire printing element 3a can be surely included. . As a result, in the detection step S3 of this embodiment, the entire print portion 3 including the poorly colored portion 3w (shown in FIG. 14) can be reliably excluded, and the contamination 9a on the outer surface 2o of the tire 1 can be detected. Therefore, it is possible to reliably improve the detection accuracy of contamination.

  In the post-process S24 of the previous embodiment, the aspect in which the rectangular area 26 is enlarged and the first area T1 is defined is exemplified, but the present invention is not limited to such an aspect. FIG. 21 is a flowchart illustrating an example of the processing procedure of the post-process S24 according to still another embodiment of the present invention. In this embodiment, the same reference numerals are given to the same configurations as those of the previous embodiments, and the description may be omitted.

  In the post-process S24 of this embodiment, first, the position of the center of gravity 32 of the print element 3a of the print unit 3 is calculated using the contour edge 22 of each print element 3a of the print unit 3 (step S251). FIG. 22 is a diagram partially showing the binarized image data 21. In step S251, first, the position of the center of gravity 32 of the region 31 surrounded by the contour edge 22 is calculated by the calculation means 18 shown in FIG. The position of the center of gravity 32 is defined as the position of the center of gravity 32 of the printing element 3a specified in the image data 21 (in this example, the printing element 3a excluding the poorly colored portion 3w).

  Next, in the post-process S24 of this embodiment, the first area T1 is defined based on the position of the center of gravity 32 and the print area size 4 (shown in FIG. 2) (process S252). FIG. 23 is a diagram illustrating the image data 21 in which the first region T1 is defined.

  In step S252, a pair of circumferential sides 36 and 36 that are separated from each other in the tire axial direction D2 by a predetermined second length L2 from the position of the center of gravity 32 and both sides of the tire circumferential direction D1 from the position of the center of gravity 32. A first region T1 formed in a rectangular shape is defined by a pair of axial sides 37 and 37 separated by a predetermined second length L2.

  The second length L2 is appropriately set based on the print area size 4 (shown in FIG. 2). The second length L2 of this embodiment is set to 0.5 to 0.7 times the side length L4 (shown in FIG. 2) of the print area size 4. Thereby, the 1st field T1 containing the whole printing element 3a of printing part 3 (namely, the whole including defective coloring part 3w) can be defined. Therefore, in this embodiment, in the detection step S3, since the printing unit 3 can be reliably excluded and the stain 9a on the outer surface 2o of the tire 1 can be detected, the printing unit 3 is erroneously detected as the stain 9a. Can be prevented. Thus, in the contamination detection method of this embodiment, the detection accuracy of contamination can be increased.

  If the second length L2 is less than 0.5 times the length L4 of one side of the print area size 4 (shown in FIG. 2), the entire print element 3a of the print unit 3 (that is, a poorly colored portion). There is a possibility that the first region T1 including the entire region including 3w cannot be defined. Conversely, if the second length L2 exceeds 0.7 times the length L4 of one side, the second region T2 (that is, the first region from the image data 21) to be detected for the contamination 9a (shown in FIG. 20). The area excluding T1) may be small, and the detection accuracy of the stain 9a may be reduced.

  In the post-process S24 of this embodiment, the first area T1 is defined based on the position of the center of gravity 32 of each printing element 3a of the printing unit 3 and the printing area size 4 (shown in FIG. 2). Thereby, the first area T1 of this embodiment is larger than the first area T1 (shown in FIG. 19) of the previous embodiment, which is defined by enlarging the rectangular area 26, and the printing elements 3a ( The deviation of the position of the center of gravity 32 of the first region T1 from the position of the center of gravity 38 of the poorly colored portion 3w) can be minimized. Accordingly, the first area T1 of this embodiment is the entire printing element 3a (coloring defect) of the printing section 3 even if the area is smaller than that of the first area T1 (shown in FIG. 19) of the previous embodiment. Part 3w). Thereby, since the stain | pollution | contamination detection method of this embodiment can enlarge 2nd area | region T2 of the detection target of the stain | pollution | contamination 9a (shown in FIG. 20), it can improve the detection accuracy of the stain | pollution | contamination 9a.

  In the post-process S24 of this embodiment, the mode in which the first region T1 is defined based on the position of the center of gravity 32 and the print region size 4 (shown in FIG. 2) is exemplified. It is not limited. For example, the first area T1 may be defined based on the position of the center 41 of the rectangular area 26 circumscribing the contour edge 22 of the printing unit 3 and the printing area size 4. FIG. 24 is a flowchart illustrating an example of the processing procedure of the post-process S24 of still another embodiment of the present invention. In this embodiment, the same reference numerals are given to the same configurations as those of the previous embodiments, and the description may be omitted.

  In the post-process S24 of this embodiment, first, the position of the center 41 of the rectangular area 26 circumscribing the contour edge 22 of the printing unit 3 is calculated (process S261). FIG. 25 is a diagram partially showing the binarized image data 21. In step S261, first, the rectangular area 26 circumscribing the contour edge 22 of the printing unit 3 is calculated by the calculation means 18 shown in FIG. The rectangular area 26 is in contact with the outermost end in the tire circumferential direction D1 of the printing element 3a and the outermost end in the tire axial direction D2. Next, in step S261, the position of the center 41 of the rectangular area 26 is calculated. The position of the center 41 is defined as the center position of the diagonal line of the rectangular area 26, for example.

  Next, in the subsequent step S24 of this embodiment, the first region T1 is defined based on the position of the center 41 and the print region size 4 (step S262). FIG. 26 is a diagram showing the image data 21 in which the first region T1 is defined.

  In step S262, a pair of circumferential sides 42 and 42 spaced by a predetermined third length L3 on both sides in the tire axial direction D2 from the position of the center 41, and on both sides of the tire circumferential direction D1 from the position of the center 41. A first region T <b> 1 formed in a rectangular shape is defined by a pair of axial sides 43 and 43 that are separated by a predetermined third length L <b> 3.

  The third length L3 is appropriately set based on the print area size 4 (shown in FIG. 2). The third length L3 of the present embodiment is 0.5 to 0 times the length L4 (shown in FIG. 2) of one side of the print area size 4 from the same viewpoint as the second length L2 of the previous embodiment. It is set to 7 times. Thereby, the 1st field T1 containing the whole printing element 3a of printing part 3 (namely, the whole including defective coloring part 3w) can be defined. Therefore, in this embodiment, in the detection step S3, since the printing unit 3 can be reliably excluded and the stain 9a on the outer surface 2o of the tire 1 can be detected, the printing unit 3 is erroneously detected as the stain 9a. Can be prevented. Thus, in the contamination detection method of this embodiment, the detection accuracy of contamination can be increased.

  Moreover, in the post-process S24 of this embodiment, the first region T1 is defined based on the position of the center 41 of each printing element 3a of the printing unit 3 and the printing region size 4 (shown in FIG. 2). . Thereby, the first area T1 of this embodiment is larger than the center (not shown) of the first area T1 (shown in FIG. 19) of the embodiment defined by enlarging the rectangular area 26. The displacement of the position of the center 41 of the first region T1 with respect to the position of the center (not shown) of the printing element 3a (including the poorly colored portion 3w) can be minimized. Therefore, even if the first area T1 of this embodiment is smaller than the first area T1 shown in FIG. 19, the entire printing element 3a of the printing section 3 (including the poorly colored portion 3w) is obtained. Can be included. Thereby, since the stain | pollution | contamination detection method of this embodiment can enlarge 2nd area | region T2 of the detection target of the stain | pollution | contamination 9a (shown in FIG. 12), the detection accuracy of the contamination | pollution | contamination 9a can be improved.

  Although the printing unit 3 of the embodiments so far has been exemplified in the tread ground plane, it is not limited to such a mode. For example, the printing unit 3 may be provided in the sidewall 2s. In this case, the image pickup means 7 is disposed on the outer side in the tire axial direction of the sidewall portion 2s, so that the printing portion 3 included in the sidewall portion 2s is prevented from being erroneously detected as fouling and attached to the sidewall portion 2s. Stain can be detected with high accuracy.

  In the embodiments so far, the mode in which the first color value is set as white and the second color value is set as black in the detection step S3 for detecting the fouling 9a is exemplified. However, the present invention is limited to such a mode. I don't mean. For example, the first color value may be set to black and the second color value may be set to white. In this case, in the binarized image data (not shown), the pixel indicating the stain 9a is displayed in black, and the pixel indicating the outer surface 2o of the tire 1 darker than the stain 9a is displayed in white. In this case, a pixel group (not shown) composed of black pixels is detected as the stain 9a.

  Although the case where it is the tire 1 was illustrated as an article from which contamination is detected in the embodiments so far, it is not limited to such an aspect. The stain detection method of the present invention can be used for various industrial products and the like as long as the printing unit 3 is provided on the outer surface. Examples of industrial products to which the present invention is applied include tubes, hoses and rubber plugs. These industrial products tend to have variations in the color density of printing, and the stain detection method of the present invention is effective. In addition, the stain detection method of the present invention is also effective for industrial products formed of a material that tends to bleed in printing, such as wood and paper, and for industrial products that are apt to fade due to the textured finish.

  As mentioned above, although especially preferable embodiment of this invention was explained in full detail, this invention is not limited to embodiment of illustration, It can deform | transform and implement in a various aspect.

  According to the processing procedure shown in FIG. 3, the contamination of the outer surface of the tire having the printing portion shown in FIG. 2 was detected (Example 1 and Example 2). In the step of defining the first area in the first embodiment, the first area is defined by enlarging the rectangular area circumscribing the contour edge of the printing element of the printing unit according to the processing procedure shown in FIG. In the step of defining the first area of the second embodiment, the first area is defined based on the position of the center of gravity of the printing element of the printing unit and the printing area size according to the processing procedure shown in FIG.

Further, for comparison, contamination of the outer surface of the tire having the printing portion shown in FIG. 2 was detected without excluding the first region that is a region including the printing portion (comparative example). The common specifications are as follows.
Tire size: 235 / 45R18 94Y
Example 1:
First length L1: 0.3 times the length L4 of one side of the print area size Example 2:
Second length L2: 0.6 times the length L4 of one side of the print area size

  As a result of the test, Example 1 and Example 2 were able to prevent the printing unit from being erroneously detected as contamination. On the other hand, the comparative example was erroneously detected with the print portion being soiled.

  Further, since the first area of the second embodiment is defined based on the position of the center of gravity of the printing unit and the print area size, compared to the first area of the first embodiment in which the rectangular area is enlarged and defined, The area could be reduced. Thereby, since Example 2 can enlarge the 2nd field compared with Example 1, it was able to raise the detection accuracy of pollution.

S1 Step of acquiring image data S2 Step of specifying first region S3 Step of detecting contamination S21 Pre-step S22 Post-step

Claims (9)

A method for detecting contamination of an outer surface of an article, comprising:
The article has a printed part colored on the outer surface with a color different from the color of the article,
The printing unit includes at least one of characters or symbols having a predetermined printing area size,
The method
Obtaining image data of the outer surface of the article;
Processing the image data to identify a first area that is an area including the printing unit;
Detecting the stain by performing image processing only on a second region that is a region obtained by removing the first region from the image data,
The step of identifying the first region includes
A pre-process for extracting a contour edge of the printing unit by image processing;
And a post-process defined as the first region based on the contour edge.   The method for detecting fouling of articles according to claim 1, wherein the post-process defines an area surrounded by the contour edge as the first area.   2. The method for detecting fouling of articles according to claim 1, wherein the post-process defines a rectangular area circumscribing the contour edge as the first area.   2. The method for detecting fouling of articles according to claim 1, wherein in the post-process, the first area is defined as an area larger than a rectangular area circumscribing the contour edge.   5. The method for detecting fouling of articles according to claim 4, wherein the post-process includes a step of defining the rectangular region and a step of defining the first region by enlarging the rectangular region. The post-process includes a step of calculating a position of the center of gravity of an area surrounded by the contour edge;
5. The method for detecting fouling of articles according to claim 4, further comprising the step of defining the first area based on the position of the center of gravity and the size of the print area. The post-process includes calculating a center position of a rectangular area circumscribing the contour edge;
5. The method for detecting fouling of articles according to claim 4, further comprising the step of defining the first area based on the center position and the print area size. The printing unit includes a plurality of printing elements composed of the characters or the symbols,
The step of specifying the first region includes a step of specifying an aggregate of pixels indicating the print element by processing the image data;
The method for detecting fouling of articles according to any one of claims 1 to 7, further comprising: specifying the aggregate as the print element when the number of the aggregate is the same as the number of the print elements.   The method for detecting fouling of an article according to any one of claims 1 to 8, wherein the article is a tire.

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