JP7573564B2 - Inspection Equipment - Google Patents

Description

The present invention relates to an imaging device and an inspection device using the imaging device.

Conventionally, an inspection device that uses an imaging device to inspect an item is described in Patent Document 1. The inspection device described in Patent Document 1 includes a first lighting system that irradiates food with a first light having a first wavelength, a second lighting system that irradiates food with a second light having a second wavelength different from the first wavelength, an imaging system that images the food irradiated with the first light and the food irradiated with the second light, and a processing system that determines that an unwanted object is present in the food when there is an area in which the absolute difference in pixel values between corresponding pixels is equal to or greater than a threshold value in the first captured image of the food irradiated with the first light and the second captured image of the food irradiated with the second light.

JP 2018-186735 A

However, in the inspection device described in Patent Document 1, the food is imaged in a time-division manner when irradiated with the first light and when irradiated with the second light, so it was essentially necessary to perform imaging twice to obtain the first and second captured images.

The present invention was made in consideration of the above-mentioned circumstances, and aims to provide an imaging device and an inspection device that can obtain multiple images of an object in a single capture.

The inspection apparatus of the present invention comprises an imaging device that images an object moving within a predetermined illumination area, the imaging device having an image generating means that generates an image of the object for each light receiving area based on imaging data output from an imaging element in which pixels are arranged in multiple rows in the direction of movement of the object and whose light receiving surface is divided into a plurality of light receiving areas along the direction of movement, and a filter that blocks light within a specific range of wavelengths that is incident on some of the plurality of light receiving areas.

With this configuration, the inspection device of the present invention can obtain, in a single imaging run, an image captured through a filter that blocks light of wavelengths within a specific range, and an image captured without passing through a filter that blocks light of wavelengths within a specific range.

In addition, in the inspection device according to the present invention, each of the light receiving areas of the imaging element is arranged with an effective pixel column, which is a column of pixels that are effective in the movement direction, and the image generating means is configured to generate an image corresponding to each of the effective pixel columns by combining line-shaped images output sequentially from each effective pixel column, respectively.

With this configuration, the inspection device according to the present invention can cause the imaging device to function as a pseudo line camera.

In the inspection device according to the present invention, the effective pixel rows are spaced apart from one another in the movement direction with at least one pixel row therebetween.

With this configuration, the inspection device according to the present invention can prevent effective pixel rows adjacent to each other in the moving direction of the article from being affected by the filter, other than the effective pixel row into which light is incident through the filter, thereby obtaining high quality images.

The inspection apparatus of the present invention includes a conveying device that conveys an inspection item as the item, and an illumination device that illuminates the inspection item with light , and is configured to inspect the inspection item based on an image captured by the imaging device.

With this configuration, the inspection device according to the present invention can obtain, in a single imaging run, an image captured through a filter that blocks light of wavelengths within a specific range, and an image captured without passing through a filter that blocks light of wavelengths within a specific range, as the inspection images used in the inspection.

In addition, in the inspection apparatus of the present invention, the imaging device continuously images the inspection product while it is being transported, and each of the multiple light receiving areas is arranged with an effective pixel row, which is a row of pixels that are effective in the movement direction, and the image generation means is configured to generate an image corresponding to each of the effective pixel rows by combining line-shaped images output sequentially from each effective pixel row, respectively.

With this configuration, the inspection device according to the present invention can make the imaging device function as a pseudo line camera.

In addition, in the inspection device according to the present invention, the illumination device illuminates light in a wavelength range including the visible light wavelength range and the near-infrared wavelength range, the multiple light receiving areas include a first light receiving area and a second light receiving area, and the first light receiving area is provided with an infrared cut filter as the filter that blocks light in the near-infrared wavelength range.

With this configuration, the inspection device according to the present invention can obtain, as inspection images, an image in which light in the near-infrared wavelength range is blocked, and an image in which light in the near-infrared wavelength range is not blocked. In other words, the inspection device according to the present invention can obtain, with a single imaging run, an inspection image in which light in the visible wavelength range is imaged, and an inspection image in which light in the near-infrared wavelength range is imaged.

In addition, in the inspection device according to the present invention, the illumination device has a first illumination device that illuminates the first light receiving area and a second illumination device that illuminates the second light receiving area, and the first illumination device is capable of illuminating light including a wavelength range of visible light, and the second illumination device is configured to illuminate light including a wavelength range of near-infrared light.

With this configuration, the inspection device according to the present invention can differentiate the wavelength ranges of light that can be illuminated by the first and second illumination devices, and can further illuminate the optimal light to each light receiving area corresponding to the light of each wavelength range.

The present invention provides an imaging device and an inspection device that can obtain multiple images of an object in a single capture.

FIG. 1 is a schematic side view of an inspection apparatus equipped with an imaging device according to an embodiment of the present invention. FIG. 2 is a schematic diagram showing an image sensor of an image pickup device according to an embodiment of the present invention. 3A and 3B are schematic top views of an imaging device according to an embodiment of the present invention.

Below, an inspection device equipped with an imaging device according to one embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the inspection device 1 of this embodiment generates a first inspection image for inspecting the appearance of an object W as an inspection product, and a second inspection image for inspecting the presence or absence of foreign matter mixed inside the object W. In the following description, the "first inspection image" and the "second inspection image" may be collectively referred to simply as "inspection images."

The inspection device 1 includes a conveying device 3 that conveys an item W, lighting devices 4a and 4b that illuminate the item W conveyed by the conveying device 3, an imaging device 5 that captures an image of the item W illuminated by the lighting devices 4a and 4b, and an image generating device 6 that serves as an image generating means for generating an inspection image of the item W based on the image captured by the imaging device 5. Using the generated inspection image, an inspection means (not shown) inspects the characteristics and quality of the item W to determine whether the external shape of the item W is good or bad, whether the packaging is good or bad, and whether there are any undesirable inclusions or attachments, and outputs the inspection results.

The conveying device 3 is, for example, a belt conveyor, and conveys the item W from the left side to the right side in the figure to a subsequent process. Examples of subsequent processes include a weighing process to check the quality of the weight, a sorting process to remove defective products, and a packaging process, and may also include an inspection process using an X-ray inspection device to check a wider variety of items.

The imaging device 5 is held on a bracket (not shown) so that its optical axis is perpendicular to the conveying surface of the conveying device 3 from a position spaced a predetermined height from the conveying surface of the conveying device 3, and captures an image of an item W moving in the imaging area Zc.

The imaging device 5 is an area camera that uses a two-dimensional element in which pixels are arranged two-dimensionally on the light receiving surface as an imaging element. That is, as shown in FIG. 2, the imaging device 5 has an imaging element 10 in which pixels 11 are arranged in multiple rows in the conveying direction, which is the direction in which the item W moves.

Figure 2 is a view of the imaging element 10 from the light receiving surface side, that is, from the lower side of the imaging device 5. In Figure 2, the numbers written in order from upstream to downstream in the transport direction represent the column numbers of the pixels 11. For ease of explanation, the number of pixels is reduced in Figure 2. For this reason, the number of pixel columns is reduced to 12 in Figure 2.

As shown in FIG. 2, the light receiving surface of the image sensor 10 is divided into multiple (two in this embodiment) light receiving regions along the transport direction. In this embodiment, the image sensor 10 has the multiple light receiving regions, a first light receiving region 12a consisting of the first to sixth pixel rows, and a second light receiving region 12b consisting of the seventh to twelfth pixel rows.

Each of the first light receiving area 12a and the second light receiving area 12b has effective pixel rows 21, 22, which are pixel rows that are effective in the transport direction of the image sensor 10. In this embodiment, the fifth row is designated as the effective pixel row 21 in the first light receiving area 12a, and the eighth row is designated as the effective pixel row 22 in the second light receiving area 12b.

An effective pixel row refers to a pixel row that is aligned in the transport direction in the imaging element 10 and that is used as one piece of data for the inspection image in the image generating device 6. In other words, the image generating device 6 specifies an effective pixel row to generate the inspection image, and generates the inspection image using only the data of the specified effective pixel row. Pixel rows other than the effective pixel row are not used to generate the inspection image.

The imaging device 5 of this embodiment therefore uses data from the effective pixel rows 21 and 22 in the imaging element 10, and can obtain line-shaped images in the width direction for each effective pixel row, similar to a line camera. The imaging device 5 continuously captures images of the item W being transported at a period corresponding to the movement of the item W, and sequentially outputs the captured data.

The line-shaped image of the effective pixel row 21 captured by the imaging device 5 is constructed as a single image by being continuously input to the first image input board 14a (described later). The line-shaped image of the effective pixel row 22 captured by the imaging device 5 is constructed as a single image by being continuously input to the second image input board 14b (described later).

In addition, it is preferable that effective pixel row 21 and effective pixel row 22 are spaced apart from each other in the transport direction, with at least one pixel row (two in this embodiment) between them. This is because if the effective pixel rows are too close to each other, the effective pixel row provided in one light receiving area will be affected by the filter provided in the other light receiving area, and so it is desirable to prevent them from being adjacent to each other in order to suppress this effect.

Of the first light receiving region 12a and the second light receiving region 12b, the first light receiving region 12a is provided with a filter 13 that blocks light of wavelengths within a specific range that is incident on at least the effective pixel row 21 of the pixel rows (rows 1 to 6) that make up the first light receiving region 12a.

The filter 13 is shown partially broken in FIG. 2, but is provided to cover all the pixels 11 in the first light receiving region 12a. No filter 13 is provided in the second light receiving region 12b.

The filter 13 is not limited to a configuration that covers all pixels 11 in the first light receiving region 12a, but may be configured to cover only a nearby pixel row including the effective pixel row 21, for example.

The filter 13 is an infrared cut filter that blocks light in the near-infrared wavelength range. In this embodiment, an infrared cut filter is used as the filter 13, but a filter that blocks light in a wavelength range other than near-infrared may be used as the filter 13 depending on, for example, the type of the item W or the purpose of the inspection.

As shown in FIG. 1, the lighting devices 4a and 4b are held by brackets (not shown) so as to illuminate the object W imaged by the imaging device 5. For example, the lighting devices 4a and 4b are arranged to sandwich the imaging device 5 in the conveying direction of the conveying device 3.

The lighting device 4a is disposed on the first light receiving area 12a side in terms of its positional relationship with the image sensor 10, i.e., upstream of the lighting device 4b in the conveying direction. The lighting device 4b is disposed on the second light receiving area 12b side in terms of its positional relationship with the image sensor 10, i.e., downstream of the lighting device 4a in the conveying direction. The lighting device 4a in this embodiment constitutes the first lighting device, and the lighting device 4b in this embodiment constitutes the second lighting device.

The lighting device 4a is configured to illuminate the first light receiving area 12a side of the image sensor 10, and is composed of a light source, such as an LED, capable of emitting light including the wavelength range of visible light.

The illumination device 4b is configured to illuminate the second light receiving area 12b side of the image sensor 10, and is configured with a light source, such as a near-infrared LED, capable of emitting light including a wavelength range of near-infrared light.

The lighting device 4a forms an illumination area Za upstream of the imaging area Zc, which is the imaging range of the imaging element 10, and the lighting device 4b forms an illumination area Zb downstream of the imaging area Zc, which is the imaging range of the imaging device 5, to illuminate the item W moved by the conveying device 3.

The positions of the illumination devices 4a and 4b and the orientation of their optical axes are preferably adjusted so that the boundary between the illumination areas Za and Zb corresponds to the boundary between the first light receiving area 12a and the second light receiving area 12b of the image sensor 10.

When the illumination areas Za and Zb are set, the pixel rows that are stably illuminated in the first light receiving area 12a and the second light receiving area 12b are set as effective pixel rows 21 and 22, respectively. Then, a sample of the item W to be actually imaged is moved or placed in the imaging area Zc to perform a test image.

The image generating device 6 is configured with a computer device equipped with multiple image input boards. The image generating device 6 generates an inspection image corresponding to each of the effective pixel rows 21, 22 by combining each of the line-shaped images of the effective pixel rows 21, 22 captured continuously by the imaging device 5 for each effective pixel row.

Specifically, the image generating device 6 has a first image input board 14a and a second image input board 14b.

Each time an image signal of the effective pixel row 21 output from the imaging device 5 is input, the first image input board 14a combines the images represented by each image signal to generate an inspection image corresponding to the effective pixel row 21 (hereinafter referred to as the "first inspection image"), i.e., a first inspection image in which light in the wavelength range of visible light is visualized.

Each time an image signal of the effective pixel row 22 output from the imaging device 5 is input, the second image input board 14b combines the images represented by each image signal to generate an inspection image corresponding to the effective pixel row 22 (hereinafter referred to as the "second inspection image"), i.e., a second inspection image in which light in the near-infrared wavelength range is visualized.

Figure 3 shows an example of a configuration in which an imaging device 5 according to one embodiment of the present invention is placed on the movement path of an item W. In Figures 3 (A) and (B), the areas surrounded by dotted lines indicate the illumination area Za illuminated by the illumination device 4a and the illumination area Zb illuminated by the illumination device 4b, respectively, and the area surrounded by a dashed dotted line indicates the imaging area Zc of the imaging device 5.

As shown in FIG. 3A, the imaging device 5 is provided between the upstream lighting device 4a and the downstream lighting device 4b based on the moving direction of the object W, and the illumination area Za illuminated by the illumination device 4a and the illumination area Zb illuminated by the illumination device 4b are formed within the imaging area Zc of the imaging device 5.

Figure 3 (B) shows a configuration in which the two lighting devices 4a and 4b in Figure 3 (A) are provided as the lighting device 4. That is, instead of the lighting devices 4a and 4b, each of which is configured with a light source of a specific wavelength range, a lighting device 4 that functions as a light source of two wavelength ranges or a broadband wavelength range is provided, thereby forming the lighting area Za and the lighting area Zb.

For example, in FIG. 3(A), the light emitted by the lighting devices 4a and 4b is reflected on the surface of the item W, and the item W is imaged using the reflected light, but the image may be captured using light that has passed through the item W.

[Action and Effect]
As described above, the imaging device of this embodiment generates an image of an object W for each of the first light receiving area 12a and the second light receiving area 12b in the imaging element 10, and a filter 13 consisting of an infrared cut filter is provided in the first light receiving area 12a.

With this configuration, the imaging device according to this embodiment can obtain an image captured through an infrared cut filter and an image captured without using an infrared cut filter in a single capture.

In addition, in the imaging device according to this embodiment, the image generating device 6 is configured to generate an inspection image corresponding to each of the effective pixel rows 21 and 22 by combining the line-shaped images sequentially output from each of the effective pixel rows 21 and 22 for each effective pixel row.

This configuration allows the imaging device according to this embodiment to function as a pseudo line camera.

In addition, in the imaging device according to this embodiment, the effective pixel row 21 and the effective pixel row 22 in the imaging element 10 are spaced apart from each other in the transport direction, sandwiching at least one pixel row (two in this embodiment).

With this configuration, the imaging device according to this embodiment can prevent the effective pixel row 22 from being affected by the filter 13 in the effective pixel row 21 and the effective pixel row 22 that are adjacent to each other in the moving direction of the article W. This makes it possible to obtain high-quality images.

The inspection device according to this embodiment has a conveying device 3 that conveys an item W, an illumination device 4 that illuminates the item W with light, and the imaging device 5 described above, and is configured to inspect the item W based on an image captured by the imaging device 5.

With this configuration, the inspection device according to this embodiment can obtain, in a single imaging run, a first inspection image captured through an infrared cut filter and a second inspection image captured without using an infrared cut filter as the inspection images to be used in the inspection.

In addition, in the inspection device according to this embodiment, the image generating device 6 is configured to generate an inspection image corresponding to each of the effective pixel rows 21 and 22 by combining the line-shaped images sequentially output from each of the effective pixel rows 21 and 22 for each effective pixel row.

With this configuration, the inspection device according to this embodiment can make the imaging device 5 function as a pseudo line camera.

In addition, in the inspection device according to this embodiment, the illumination device 4a illuminates light including the wavelength range of visible light, the illumination device 4b illuminates light including the wavelength range of near-infrared light, and the first light receiving area 12a is provided with an infrared cut filter as a filter 13 that blocks light in the wavelength range of near-infrared light.

With this configuration, the inspection device according to this embodiment can obtain, as inspection images, an image in which light in the near-infrared wavelength range is blocked, and an image in which light in the near-infrared wavelength range is not blocked. In other words, the inspection device according to this embodiment can obtain, in a single imaging run, a first inspection image in which light in the visible wavelength range is imaged, and a second inspection image in which light in the near-infrared wavelength range is imaged.

The inspection device according to this embodiment also has an illumination device 4a that illuminates the first light receiving area 12a with light that includes the wavelength range of visible light, and an illumination device 4b that illuminates the second light receiving area 12b with light that includes the wavelength range of near-infrared light.

With this configuration, the inspection device according to this embodiment can differentiate the wavelength ranges of light that can be illuminated by the illumination device 4a and the illumination device 4b, and can further illuminate the light receiving area corresponding to the light of each wavelength range with the optimal light.

(Variation 1)
In this embodiment, an example has been described in which the imaging device 5 functions as a pseudo-line camera by providing effective pixel rows 21 and 22 in the imaging element 10, but this is not limited to the above, and the imaging device 5 may also function as an area camera.

In this case, the imaging element 10 does not have effective pixel rows. Therefore, the image generating device 6 generates an inspection image corresponding to the first light receiving area 12a and an inspection image corresponding to the second light receiving area 12b based on data from the pixel rows constituting each of the first light receiving area 12a and the second light receiving area 12b.

(Variation 2)
In the present embodiment, an example has been described in which the filter 13 is provided in the first light receiving region 12a and no filter is provided in the second light receiving region 12b.

In contrast, a filter according to the purpose of the inspection may also be provided in the second light receiving area 12b. In this case, a filter that blocks a different wavelength range of light than the filter 13 is provided in the second light receiving area 12b. For example, an infrared transmission filter that transmits infrared light may be provided in the second light receiving area 12b.

(Variation 3)
In the present embodiment, an example in which the filter 13 is provided in the first light receiving region 12a has been described. However, a filter may be provided in a corresponding region of the lens of the imaging device 5. For example, a filter may be provided in a region of the lens of the imaging device 5 that corresponds to the first light receiving region 12a.

(Variation 4)
In the present embodiment, the filter 13 that blocks light having a wavelength within a specific range is provided in the first light receiving region 12a. Alternatively, a scintillator may be provided as the filter 13 in the first light receiving region 12a.

(Variation 5)
In the present embodiment, an example has been described in which the light receiving surface of the image sensor 10 is divided into two light receiving regions. However, the light receiving surface of the image sensor 10 may be divided into three or more light receiving regions, and each of the light receiving regions may be provided with an effective pixel row.

In this case, the image generating device 6 is provided with a number of image input boards corresponding to the number of light receiving areas. In addition, the three or more light receiving areas may be, for example, a combination of a light receiving area without a filter, a light receiving area with a filter that blocks light in the near-infrared wavelength range, and a light receiving area with a filter that blocks light in a wavelength range excluding at least one of the wavelength ranges of the red, green, and blue components contained in visible light.

(Variation 6)
In the present embodiment, an example in which each light receiving region has one effective pixel row has been described, but the present invention is not limited to this, and each light receiving region may have two or more effective pixel rows. In this case, the effective pixel rows in each light receiving region are made up of multiple rows that are continuous in the transport direction.

(Variation 7)
In the present embodiment, an example in which two lighting devices, 4a and 4b, are provided has been described, but the present invention is not limited to this, and any one of the lighting devices 4a and 4b may be provided, or three or more lighting devices may be provided. In the case of configuring a single lighting device, it is preferable to expand the irradiation area of the lighting device to the first light receiving area 12a and the second light receiving area 12b, and to use a light source such as a halogen lamp that illuminates light in a wavelength range including the wavelength range of visible light and the wavelength range of near-infrared light.

(Variation 8)
In the present embodiment, the illumination devices 4a and 4b are configured with light sources that emit light of different wavelength ranges. Alternatively, the illumination devices 4a and 4b may each be configured with a light source such as a halogen lamp that emits light of a wavelength range that includes the wavelength range of visible light and the wavelength range of near-infrared light.

(Variation 9)
In this embodiment, a configuration has been described in which the imaging device 5 outputs data for all pixel rows that make up the imaging element 10 to the image generating device 6, and the image generating device 6 generates an inspection image using only the data for effective pixel rows out of the data for all pixel rows.

In contrast, the imaging device 5 may be configured to output only data of effective pixel rows among all pixel rows that make up the imaging element 10 to the image generating device 6, and the image generating device 6 may generate an inspection image using only the data of the effective pixel rows input from the imaging device 5.

(Variation 10)
Furthermore, the imaging device 5 may output data of each effective pixel row to the image generating device 6 based on a timing signal transmitted from the image generating device 6 according to the transport speed.

Although an embodiment of the present invention has been disclosed, it is apparent that modifications may be made by one of ordinary skill in the art without departing from the scope of the present invention. All such modifications and equivalents are intended to be included in the following claims.

1 Inspection device 3 Transport device 4a Illumination device (first illumination device)
4b Illumination device (second illumination device)
5 Imaging device 6 Image generating device (image generating means)
10: Image sensor 11: Pixel 12a: First light receiving region (light receiving region)
12b Second light receiving area (light receiving area)
13 Filter 21, 22 Effective pixel row W Item (inspection item)
Za 1st illumination area (illumination area)
Zb Second illumination area (illumination area)
Zc imaging area

Claims (7)

The imaging device (5) captures an image of an object (W) moving in a predetermined illumination area (Za, Zb), the imaging device having an image generating means (6) for generating an image of the object for each light receiving area based on imaging data output from an imaging element (10) configured with pixels (11) arranged in multiple rows in the moving direction of the object and a light receiving surface divided into multiple light receiving areas (12a, 12b) along the moving direction, and a filter (13) for blocking light within a specific wavelength range that is incident on a part of the multiple light receiving areas (12a) ,
A conveying device (3) for conveying an inspection product (W) as the article;
An illumination device (4) for illuminating the inspection item with light,
An inspection apparatus that inspects the inspection product based on an image captured by the imaging device,
The imaging device continuously images the inspection product during transportation,
an effective pixel row, which is a row of pixels that is effective in the moving direction, is arranged in each of the plurality of light receiving regions;
the image generating means generates an image corresponding to each of the effective pixel rows by combining, for each effective pixel row, line-shaped images sequentially output from each effective pixel row;
The illumination device illuminates light having a wavelength range including a visible light wavelength range and a near-infrared light wavelength range,
The plurality of light receiving regions include a first light receiving region (12a) and a second light receiving region (12b),
An inspection device characterized in that the first light receiving region is provided with an infrared cut filter as the filter, which blocks light in a near-infrared wavelength range. The illumination device includes a first illumination device (4a) that illuminates the first light receiving area and a second illumination device (4b) that illuminates the second light receiving area,
the first lighting device is capable of emitting light having a wavelength range of visible light;
2. The inspection apparatus according to claim 1 , wherein the second illumination device is capable of emitting light including a wavelength range of near-infrared light. 3. The inspection apparatus according to claim 1, wherein the effective pixel rows are spaced apart from one another in the movement direction with at least one pixel row therebetween. The imaging device (5) captures an image of an object (W) moving in a predetermined illumination area (Za, Zb), the imaging device having an image generating means (6) for generating an image of the object for each light receiving area based on imaging data output from an imaging element (10) configured with pixels (11) arranged in multiple rows in the moving direction of the object and a light receiving surface divided into multiple light receiving areas (12a, 12b) along the moving direction, and a filter (13) for blocking light within a specific wavelength range that is incident on a part of the multiple light receiving areas (12a),
A conveying device (3) for conveying an inspection product (W) as the article;
An illumination device (4) for illuminating the inspection item with light,
An inspection apparatus that inspects the inspection product based on an image captured by the imaging device,
The illumination device illuminates light having a wavelength range including a visible light wavelength range and a near-infrared light wavelength range,
The plurality of light receiving regions include a first light receiving region (12a) and a second light receiving region (12b),
An inspection device characterized in that the first light receiving region is provided with an infrared cut filter as the filter, which blocks light in a near-infrared wavelength range. The illumination device includes a first illumination device (4a) that illuminates the first light receiving area and a second illumination device (4b) that illuminates the second light receiving area,
the first lighting device is capable of emitting light having a wavelength range of visible light;
5. The inspection apparatus according to claim 4 , wherein the second illumination device is capable of emitting light including a wavelength range of near-infrared light. an effective pixel row, which is a row of pixels that is effective in the moving direction, is arranged in each of the light receiving regions of the image sensor;
6. The inspection device according to claim 4, wherein the image generating means generates an image corresponding to each of the effective pixel columns by combining line-shaped images sequentially output from each effective pixel column, for each effective pixel column . 7. The inspection apparatus according to claim 6 , wherein the effective pixel rows are spaced apart from one another in the movement direction with at least one pixel row therebetween.

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