JP2020187696A - Foreign matter/mark discrimination method, sheet inspection device, and program - Google Patents

Abstract

To provide a foreign matter/mark discrimination method capable of accurately discriminating a foreign matter from a mark even when the shape of the mark is similar to that of the foreign matter.SOLUTION: The foreign matter/mark discrimination method includes the steps of: extracting a contour of a candidate of a foreign matter or mark from an image of a sheet in which foreign matters and marks are mixed (step S71); and tracking the contour to track the contour in one direction from any starting point on the contour and determining whether the contour tracking path is continuous and goes around the contour without intersecting and returns to the starting point (steps S72, S73). When the determination is NO, the candidate is determined as a foreign body, and when the determination is not NO, the candidate is determined as a mark.SELECTED DRAWING: Figure 7

Description

The present invention relates to a method for discriminating between a foreign substance and a mark by image processing.

Patent Document 1 describes an optical reader capable of discriminating between foreign matter such as dust and entry marks. In this optical reading device, the medium on which the mark is written is read by a scanner. Obtain the vector distribution of the contours of mark and foreign matter candidates from the output image of the scanner. If there are few types of vectors and the distribution is biased, the candidate is judged as a mark. When there are many types of vectors and they are discrete, the candidate is judged as a foreign substance.

Japanese Unexamined Patent Publication No. 2008-282232

However, when the foreign matter and the mark have similar shapes, the vector types and distributions are similar. Therefore, in the optical reading device described in Patent Document 1, it is difficult to accurately discriminate between the foreign matter and the mark when the shape of the mark is similar to that of the foreign matter.
An object of the present invention is to accurately discriminate between a foreign matter and a mark even when the shape of the mark is similar to that of the foreign matter.

In order to achieve the above object, the foreign matter mark discrimination method of the present invention extracts the contour of the foreign matter or mark candidate from a photographed image of a sheet in which the foreign matter and the mark coexist, and from an arbitrary start point on the contour. The contour tracking for tracking the contour in one direction is performed, and it is determined whether or not the contour tracking path goes around the contour continuously and without intersecting and returns to the starting point, and the determination is rejected. If, the candidate is determined to be the foreign substance, and if the determination is not negative, the candidate is determined to be the mark.

According to the present invention, even when the foreign matter and the mark have similar shapes, the foreign matter and the mark can be accurately discriminated.

It is a figure for demonstrating the laminated sheet inspection method by 1st Embodiment of this invention. It is a block diagram which shows the structure of the system which executes the laminated sheet inspection method shown in FIG. It is a figure for demonstrating an example of a mark. It is a figure for demonstrating an example of the foreign matter existing in a laminated sheet. It is a figure for demonstrating the vector distribution of a mark. It is a figure for demonstrating the vector distribution of a foreign substance. It is a flowchart which shows the detailed procedure of the discrimination process using contour tracking and area ratio. It is a figure for demonstrating the contour tracking of a mark. It is a figure for demonstrating contour tracking of a foreign body. It is a figure for demonstrating another example of a foreign substance. It is a figure for demonstrating an example of the photographed image of the foreign matter shown in FIG. It is a figure for demonstrating the result of contour extraction and contour tracking for the photographed image whose line width is represented by a plurality of pixels.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. However, the components described in the embodiments are merely examples, and the scope of the present invention is not intended to be limited thereto.

(First Embodiment)
FIG. 1 is a diagram for explaining a laminated sheet inspection method according to the first embodiment of the present invention.
Referring to FIG. 1, in step S11, a first foreign matter inspection for detecting a foreign matter on the sheet alone is performed. In this first foreign matter inspection, a mark corresponding to the detected foreign matter is given to the sheet. The mark has a shape that allows contour tracing. Specifically, when the contour is traced in one direction from an arbitrary start point on the contour, a mark having a shape such that the contour tracking path goes around the contour continuously and returns to the start point without intersecting. Is used. For example, as marks, a plurality of types of marks such as "○", "□", "△", and "◎" can be used, and different types of marks can be used depending on the amount of foreign matter (for example, area and shape). A mark may be given.

Next, in step S12, the sheets are laminated to form a laminated sheet. This laminated sheet includes the sheet subjected to the first foreign matter inspection in step S11, and the foreign matter and the mark are mixed.
Next, in step S13, a second foreign matter inspection for detecting foreign matter is performed on the laminated sheet. This second foreign matter inspection includes a foreign matter mark discrimination process for discriminating between a foreign matter and a mark. In the foreign matter mark discrimination process, first, the outlines of foreign matter or mark candidates are extracted from the photographed image of the laminated sheet. Next, contour tracking is performed to trace the contour in one direction from an arbitrary start point on the contour, and whether or not the contour tracking path goes around the contour continuously and without intersecting and returns to the start point. judge. If the determination is negative, the candidate is determined to be a foreign substance, and if the determination is not negative, the candidate is determined to be a mark.
Further, for the candidates for which the above determination is not negative, the area ratio, which is the ratio of the number of pixels occupied by the candidate area in the captured image to the area value of the entire figure indicated by the contour, may be obtained. In this case, if the area ratio is larger than the predetermined threshold value, the candidate is determined as a foreign substance, and if the area ratio is equal to or less than the threshold value, the candidate is determined as a mark.

Finally, in step S14, the quality of the laminated sheet is determined. The criteria for judging quality are, for example, the type and distribution of marks. The quality of the laminated sheet may be determined according to the type of mark. Further, when a certain number or more of marks are present within a certain range, the portion may be determined to be defective. In addition, various judgment criteria can be applied to the quality judgment of the laminated sheet.
After the quality determination in step S14, the laminated sheet is cut out to a predetermined size with the defective portion removed. Both ends of the cut-out laminated sheet are thermocompression-bonded to form an endless belt to form the final product.

FIG. 2 is a block diagram showing a configuration of a system that executes the laminated sheet inspection method shown in FIG.
The system shown in FIG. 2 includes a sheet inspection device 21 and a marking device 24. The sheet inspection device 21 has a photographing unit 22 and an image processing unit 23. The photographing unit 22 has at least one camera for photographing the sheet to be inspected. The camera has interchangeable lenses and can be fitted with lenses of any performance. Here, the camera and the lens may be selected so that the size of one pixel on the image sensor is equal to or less than the line width of the foreign matter to be inspected. For example, when the line width of the foreign matter is 25 μm, the camera and the lens may be selected so that one side of the square pixel is 25 μm or less. In this case, the line width of the foreign matter on the captured image is represented by one pixel.
When photographing the sheet, a lighting device suitable for foreign matter inspection of the sheet is used so that a photographed image having high contrast can be obtained. The illuminating device may have, for example, a transmission illuminating unit and a reflection illuminating unit. In this case, the photographing unit 22 can perform photographing for foreign matter inspection by using both transmission illumination and reflection illumination in combination.

Hereinafter, the operation of each part of the system shown in FIG. 2 will be described in relation to the steps shown in FIG.
In step S11, the photographing unit 22 photographs a single sheet and outputs the captured image (data) to the image processing unit 23. The image processing unit 23 performs image processing on the captured image of the sheet alone, and performs the first foreign matter inspection. In the first foreign matter inspection, the image processing unit 23 outputs the foreign matter determination result including the foreign matter detection data to the marking device 24. The foreign matter detection data includes the coordinate data of the foreign matter in the coordinate system of the photographing unit 22.
A correspondence is taken in advance between the coordinate system of the photographing unit 22 and the coordinate system of the marking device 24. The marking device 24 gives a mark corresponding to the foreign matter to a predetermined position on the sheet based on the foreign matter detection data received from the sheet inspection device 21. The marking position is a position corresponding to the position of the foreign matter. The position of the foreign matter can be specified based on the position where the mark is applied. It is desirable to give a mark to all foreign substances.

After forming the laminated sheet, in step S13, the photographing unit 22 photographs the laminated sheet and outputs the photographed image (data) to the image processing unit 23. The image processing unit 23 performs image processing on the captured image of the laminated sheet and performs a second foreign matter inspection. In the second foreign matter inspection, the image processing unit 23 performs the discrimination processing using the contour tracking and the discrimination processing using the area ratio with respect to the foreign matter or mark candidate.
After the discrimination process, in step S14, the image processing unit 23 determines the quality of the laminated sheet based on the type and distribution of the marks.
According to the above-mentioned laminated sheet inspection method, by performing the discrimination process (primary judgment) using contour tracking, it is possible to accurately discriminate between the foreign matter and the mark even if the shapes of the foreign matter and the mark are similar.

The effects of the discrimination process using contour tracking will be described in detail below.
FIG. 3 shows an example of the mark given to the sheet by the marking device 24. This mark has a shape such that when the contour is traced in one direction from an arbitrary start point on the contour, the contour tracking path is continuous, goes around the contour without intersecting, and returns to the start point. , It is a hollow shape. FIG. 3A is a schematic view of the mark 31 given to the sheet according to the data. FIG. 3B is a schematic view of the mark 32 applied to a sheet having a rough surface such as a non-woven fabric. The mark 31 has a perfect circular shape. On the other hand, the shape of the mark 32 is irregular as compared with the mark 31.

FIG. 4 shows an example of foreign matter existing in the laminated sheet. 4 (a) and 4 (b) are schematic views of fiber-based foreign substances 41 and 42, which are often found in non-woven fabrics. The foreign substances 41 and 42 are both string-shaped. The foreign matter 41 has a shape similar to that of the mark 31 shown in FIG. 3A, but both ends intersect. The foreign matter 42 has a shape similar to that of the mark 32 shown in FIG. 3B, but both ends are not connected.
In the discrimination method using the vector distribution of the contour described in Patent Document 1, it is difficult to accurately discriminate between the foreign matter 41 and the mark 31 having similar shapes, or the foreign matter 42 and the mark 42 having similar shapes. The reason why the foreign matter and the mark cannot be accurately discriminated will be described below with reference to FIGS. 5 and 6.

FIG. 5A is a vector distribution of the mark 31 shown in FIG. 3A. FIG. 6A is a vector distribution of the foreign matter 41 shown in FIG. 4A. In FIGS. 5 (a) and 6 (a), the arrow 51 indicates a vector. Since the mark 31 and the foreign matter 41 are similar in shape to each other, the directions and sizes of the respective arrows 51 are substantially the same. That is, there is no difference in the amount or discreteness of the vector species between the mark 31 and the foreign matter 41. Therefore, it is difficult to discriminate between the foreign matter 41 and the mark 31 using the vector distribution.
FIG. 5B is a vector distribution of the mark 32 shown in FIG. 3B. FIG. 6B is a vector distribution of the foreign matter 42 shown in FIG. 4B. In FIGS. 5 (b) and 6 (b), arrow 52 indicates a vector. Like the mark 31 and the foreign matter 41, the mark 32 and the foreign matter 42 are similar in shape to each other, so that the directions and sizes of the respective arrows 52 are substantially the same. That is, there is no difference in the amount or discreteness of the vector species between the mark 32 and the foreign matter 42. Therefore, it is difficult to discriminate between the foreign matter 42 and the mark 32 using the vector distribution.

On the other hand, according to the discrimination process using the contour tracking of the present embodiment, the judgment of the contour tracking in step S13 of FIG. 1 is rejected for any of the foreign substances 41 and 42. On the other hand, for each of the marks 31 and 32, the determination of the contour tracking in step S13 of FIG. 1 cannot be denied. In this way, the foreign matter 41 and the mark 31 having similar shapes and the foreign matter 42 and the mark 42 having similar shapes can be accurately discriminated.
Further, in the present embodiment, the discrimination process (secondary determination) using the area ratio is performed on the candidate determined as a mark by the discrimination process (primary determination) using contour tracking. This makes it possible to discriminate the mark more reliably.

The procedure of discrimination processing using contour tracking and area ratio will be described in detail below.
FIG. 7 shows a detailed procedure of contour tracking and discrimination processing using area ratio. Hereinafter, the discrimination process will be described with reference to FIG. 7.

First, in step S71, the image processing unit 23 performs contour extraction processing on the captured image data input from the photographing unit 22. For example, the photographing unit 22 supplies the photographed image data of 256 gradations to the image processing unit 23. The image processing unit 23 detects a region having a constant density change from the density value of the background region as a foreign matter or a mark candidate. Then, the image processing unit 23 extracts the boundary between the background area and the candidate, that is, the outermost pixel of the candidate as a contour. It is desirable to remove the detected candidates whose area is smaller than the preset threshold value as a noise component.

Next, in step S72, contour tracking processing is performed on the data for which contour extraction has been performed. Here, the contour tracking process will be specifically described with reference to FIGS. 8 and 9.
FIG. 8A shows the image processing result of the contour tracking of the mark 31 shown in FIG. 3A, and FIG. 8B shows the image processing of the contour tracking of the mark 32 shown in FIG. 3B. The result is shown. FIG. 9A shows the image processing result of the contour tracking of the foreign matter 41 shown in FIG. 4A, and FIG. 9B shows the image processing of the contour tracking of the foreign matter 42 shown in FIG. 4B. The result is shown. In FIGS. 8 and 9, one cell corresponds to one pixel of the camera of the photographing unit 22. Here, the result of performing the contour tracking process in the inspection area composed of 22 × 22 pixels is shown. Distinguish between foreign matter or mark candidates and the background area based on the density value of each pixel. The squares shown in the thick frame are candidates for foreign objects 41, 42 or marks 31 and 32, and the other squares are background areas.

First, the start point 81 is set on the extracted contour. In the examples of FIGS. 8 (a) and 8 (b), the squares of the coordinates (X9, Y3) are set at the start point 81. In the example of FIG. 9A, the squares of the coordinates (X11, Y0) are set at the start point 81. In the example of FIG. 9B, the squares of the coordinates (X10, Y3) are set at the start point 81. The setting of the start point 81 is not limited to this, and the start point 81 may be set anywhere on the contour.
Next, contour tracking 82 that traces the contour in one direction from the start point 81 is executed. The end of the contour tracking 82 is until it returns to the start point 81 or until there is a break in the contour. The direction of the contour tracking 82 may be any direction as long as the contour can be traced.

See FIG. 7 again. After the contour tracking process in step S72, the primary determination based on the result of the contour tracking 82 is performed in step S73. The condition of this primary determination is whether or not the path of the contour tracking 82 goes around the contour continuously and without intersecting and returns to the starting point 81. Here, crossing means passing through the same pixel.
In both the examples of FIGS. 8 (a) and 8 (b), the route of the contour tracking 82 goes around the contour continuously and without intersecting and returns to the starting point 81, so that the condition of the primary determination is satisfied. .. Therefore, the determination in step S73 is "Yes", and the candidate is determined as a mark.

On the other hand, in the example of FIG. 9A, the path of the contour tracking 82 continuously passes through the entire contour from the start point 81 of the coordinates (X11, Y0), but the squares (pixels) of the coordinates (X10, Y1) are used. As twice, the coordinates of the end point (X9, Y0) are different from the start point 81. In the example of FIG. 9B, the route of the contour tracking 82 continuously passes through the entire contour from the start point 81 of the coordinates (X10, Y3), but the coordinates (X13, Y3) of the end point are different from the start point 81. As described above, neither of the examples of FIGS. 9 (a) and 9 (b) satisfies the condition of the primary determination. Therefore, the determination in step S73 is "No", and the candidate is determined to be a foreign substance.

When the determination in step S73 is "Yes", the area ratio is subsequently measured in step S74. Here, the area ratio is the ratio of the second area value to the first area value. The first area value is the area value of the entire figure indicated by the contour captured by the image processing. The second area value is the number of pixels occupied by the candidate area captured by the image processing.
Next, in step S75, it is determined whether or not the area ratio is equal to or less than a predetermined threshold value. If the determination in step S74 is "Yes", the candidate is determined to be a mark, and in step S76, the process corresponding to the mark determination is executed. If the determination in step S73 is "No", or if the determination in step S74 is "No", the candidate is determined to be a foreign matter, and in step S77, the process corresponding to the foreign matter determination is executed.

According to the discrimination process described above, the foreign matter having a similar shape and the mark can be discriminated by the primary determination in step S73, and the mark can be discriminated more reliably by the secondary determination in step S75. ..
For example, as shown in FIG. 8A, the figure indicated by the outline of the mark 31 in the photographed image of the mark 31 shown in FIG. 3A is a circle having a diameter of 16 pixels. In this case, the first area value is given by 8 × 8 × π = about 200 pixels according to the area of a circle formula. The second area value is the number of pixels in the contour portion composed of the squares of the thick frame, that is, 44 pixels. Therefore, the area ratio is 44/200.

On the other hand, some foreign substances such as stains and stains have a shape similar to that of the mark 31. FIG. 10 shows an example of a filled foreign matter having a shape similar to that of the mark 31. FIG. 11 shows a photographed image of the foreign matter 101 shown in FIG. The area value of the entire figure indicated by the outline of the foreign matter 101 in the photographed image of the foreign matter 101 is the first area value. The first area value of the foreign matter 101 is the same as the first area value of the mark 31 shown in FIG. 8A, and is about 200. However, as shown in FIG. 11, the second area value of the foreign matter 101 is the number of pixels of the filled portion (thick frame), which is 216. The second area value of the foreign matter 101 is larger than the second area value of the mark 31. The first area value and the second area value of the foreign matter 101 are substantially the same value, and the area ratio is 216/200. As described above, the area ratio of the foreign matter 101 is sufficiently larger than the area ratio of the mark 31. Therefore, a threshold value capable of distinguishing the foreign matter 101 and the mark 31 is set, and if the area ratio is larger than the threshold value, the candidate is determined to be the foreign matter 101, and if the area ratio is equal to or less than the threshold value, the candidate is determined to be the mark 31. Can be done. In this way, by performing the secondary determination using the area ratio, it is possible to more reliably discriminate between the foreign matter and the mark.

Even if the foreign matter has a shape similar to that of the mark, there are few that satisfy the condition of the primary judgment that the contour tracking path is continuous, goes around the contour without intersecting, and returns to the starting point. Therefore, if a mark having a shape satisfying the condition of the primary determination is used, the foreign matter and the mark can be discriminated even if the foreign matter and the mark have similar shapes. For example, when a mark is given to a sheet having a rough surface such as a non-woven fabric, it is possible to distinguish the mark from the foreign matter even if the given mark has an irregular shape similar to a foreign matter.
Further, the area ratio of the mark having a shape satisfying the condition of the primary determination is different from the area ratio of foreign matter such as stains and stains. Therefore, by performing the secondary determination based on the area ratio, it is possible to more reliably determine the foreign matter and the mark.
Further, the discrimination process using the mark having a shape satisfying the condition of the primary judgment can be realized by software, and it is not necessary to change the hardware. Therefore, it is also advantageous in terms of cost.

(Second Embodiment)
The laminated sheet inspection method according to the second embodiment of the present invention differs from the first embodiment only in the contour extraction process in step S71 shown in FIG. 7. In order to avoid duplication of description, detailed description of the same processing as in the first embodiment will be omitted below.
In the laminated sheet inspection method according to the first embodiment, the line width of foreign matter and mark candidates on the captured image is represented by one pixel. On the other hand, in the present embodiment, the candidate line width is represented by a plurality of pixels.

FIG. 12A is a schematic diagram showing the results of contour extraction and contour tracking for an image of the foreign matter 41 shown in FIG. 4A taken so that the line width is represented by a plurality of pixels.
As shown in FIG. 12A, contour extraction is performed on a captured image in which the line width of the foreign matter 41 is represented by a plurality of pixels, and the contour is traced in one direction from the start point 81 of the coordinates (X6, Y0). Perform contour tracking 82. In this case, since the path of the contour tracking 82 goes around the contour continuously and without intersecting and returns to the starting point 81, the condition of the primary determination is satisfied. As a result, the candidate is erroneously identified as a mark.

Therefore, in the present embodiment, in the contour extraction process of step S71, the foreign matter or mark candidate captured in the image processing is approximated to a figure whose line width is represented by one pixel, and the contour is extracted based on the figure. .. FIG. 12B is a schematic diagram showing an example of the image after the approximation processing. In this example, the central pixel is extracted from the three pixels of the line width of the foreign matter 41 to approximate the figure 121 having a line width of one pixel.
Any approximation processing may be applied as long as the candidate can be approximated to a figure having a line width of 1 pixel. For example, approximation processing may be performed by applying preprocessing such as a contour extraction filter used in general image processing. Further, the line width of a plurality of pixels may be pseudo-converted into one pixel, that is, one pixel unit to extract the contour.
The laminated sheet inspection method of the present embodiment also has the same effect as that of the first embodiment.

The first and second embodiments described above are examples of the present invention, and the configuration and the order of processing thereof can be appropriately changed.
For example, in the laminated sheet inspection method of the first embodiment, contour extraction using the approximation performed in the second embodiment may be incorporated. Specifically, for a captured image in which the candidate line width is represented by one pixel, contour extraction processing is performed without applying approximation, and the captured image in which the candidate line width is represented by a plurality of pixels is subjected to contour extraction processing. Then, the contour extraction process to which the approximation is applied is performed. Then, for each contour extracted image, the contour tracking process of step S72 and the primary determination of S73 are performed.
Further, the image processing including the discrimination processing described in the first and second embodiments may be realized by executing a program by a computer such as a microprocessor (MPU) or a CPU (Central Processing Unit). In this case, for example, the program may cause the computer to execute all or part of the processes of steps S71 to S77 of FIG. Some processes are, for example, the processes of steps S71 to S73.
Further, the above program may be provided to the system or device via a network such as the Internet or various storage media. The storage medium includes, for example, a semiconductor memory, a magnetic recording medium, an optical disk, and the like.

21 Sheet inspection device 22 Imaging unit 23 Image processing unit 24 Marking device

Claims (8)

The outline of the foreign matter or mark candidate is extracted from the photographed image of the sheet in which the foreign matter and the mark are mixed.
Whether or not contour tracking is performed to track the contour in one direction from an arbitrary start point on the contour, and the contour tracking path goes around the contour continuously and without intersecting and returns to the start point. Judging,
A method for determining a foreign matter mark, which comprises determining the candidate as the foreign matter when the determination is negative, and determining the candidate as the mark when the determination is not negative. The method for determining a foreign matter mark according to claim 1, further comprising extracting the outermost peripheral pixel of the candidate as the contour. The method for determining a foreign matter mark according to claim 1 or 2, wherein the foreign matter is string-shaped, and the line width of the foreign matter is represented by one pixel on the photographed image. When the foreign matter is string-shaped and the line width of the foreign matter is represented by a plurality of pixels on the captured image, the candidate for the foreign matter is approximated to a figure whose line width is represented by one pixel, and the figure. The method for determining a foreign matter mark according to claim 1 or 2, wherein the contour is extracted based on the above. When the area ratio, which is the ratio of the number of pixels occupied by the candidate area in the captured image to the area value of the entire figure indicated by the contour, is larger than a predetermined threshold value, the candidate is determined to be the foreign substance, and the above. The method for determining a foreign matter mark according to any one of claims 1 to 4, wherein the candidate is determined to be the mark when the area ratio is equal to or less than the threshold value. A shooting unit that shoots a sheet with a mixture of foreign matter and marks and outputs the shot image,
It has an image processing unit that processes the captured image to discriminate between the foreign matter and the mark.
The image processing unit
The outline of the foreign matter or mark candidate is extracted from the photographed image, and the outline is extracted.
Whether or not contour tracking is performed to track the contour in one direction from an arbitrary start point on the contour, and the contour tracking path goes around the contour continuously and without intersecting and returns to the start point. Judging,
A sheet inspection apparatus, characterized in that, if the determination is negative, the candidate is determined to be the foreign substance, and if the determination is not negative, the candidate is determined to be the mark. The procedure for extracting the outline of the foreign matter or mark candidate from the photographed image of the sheet in which the foreign matter and the mark are mixed, and
Whether or not contour tracking is performed to track the contour in one direction from an arbitrary start point on the contour, and the contour tracking path goes around the contour continuously and without intersecting and returns to the start point. And the procedure to judge
A program for causing a computer to execute a procedure of determining the candidate as the foreign substance when the determination is negative, and determining the candidate as the mark when the determination is not negative. This is an inspection method for laminated sheets, which is made by laminating multiple sheets.
The process of performing the first foreign matter inspection to detect foreign matter on the sheet alone and giving a mark to the sheet according to the detected foreign matter,
The first foreign matter inspection is performed, and the step of performing a second foreign matter inspection for detecting a foreign matter on a laminated sheet in which the plurality of sheets are laminated is included.
The mark goes around the contour continuously and without intersecting when the contour tracking is performed to trace the contour in one direction from an arbitrary start point on the contour of the mark. It has a shape that returns to the starting point.
The second foreign matter inspection is
The outline of the foreign matter or mark candidate is extracted from the photographed image obtained by photographing the laminated sheet.
It is determined whether or not the extracted contour has the shape of the mark, and it is determined.
A laminated sheet inspection method comprising determining the candidate as the foreign substance when the determination is negative, and determining the candidate as the mark when the determination is not negative.