JP2017021275A - Image acquisition device - Google Patents

Abstract

A small-scale image acquisition apparatus capable of acquiring an image of a sample at high speed and with high resolution is provided.
An image acquisition apparatus 1000 that acquires image data of a slide, includes a first imaging unit 11, a first holding mechanism 102, and a second holding mechanism 124, and is held by a second holding mechanism 124. A second image pickup unit 12 for picking up an image of the slide 2, a slide storage unit 101 in which a plurality of slides are stored, and a control unit 13, and slides from the slide storage unit 101 by the first holding mechanism 102. 2 is taken out, the slide 2 is transported to a predetermined position of the first imaging unit 11, the first imaging unit 11 performs imaging of the slide 2 held by the first holding mechanism 102, and the first holding mechanism 102. The slide 2 is conveyed to the second holding mechanism 124, the position of the slide 2 is adjusted by the second holding mechanism 124, and held by the second holding mechanism 124 by the second imaging unit 12. Is performing imaging of the slide 2 are.
[Selection] Figure 1

Description

  The present invention relates to an image acquisition apparatus, and more particularly to an image acquisition apparatus for acquiring a high-magnification and high-resolution image of a specimen at high speed.

  In the field of pathology and the like, as an alternative to an optical microscope, an image acquisition apparatus that acquires a digital image by imaging a sample has attracted attention. This apparatus enables a doctor to diagnose a medical condition using the acquired image data. This type of apparatus is called a digital microscope system, a slide scanner, a virtual slide system, or the like. By digitizing the pathological diagnosis image, for example, by grasping the shape of the cell, calculating the number of cells, and calculating the area ratio between the cytoplasm and the nucleus, various information useful for pathological diagnosis can be presented.

  This type of system is required to capture a slide at high speed and high speed. Therefore, in order to efficiently acquire a high-resolution digital image, an imaging apparatus has been proposed in which an area where a specimen is present on a slide is measured in advance by macro-imaging the slide, and high-resolution imaging is performed only in that area. (Patent Document 1). In addition, an imaging apparatus having a preview camera and a high-magnification imaging unit and having a routine for searching for a pixel in which a specimen exists from a preview image has been proposed (Patent Document 2).

JP 2007-310231 A Special table 2009-528580

  However, the devices in these documents share a stage between the macro imaging unit and the micro imaging unit, and the stage itself becomes large by sharing the stage in this way. May become excessive.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a small-scale image acquisition apparatus that can acquire an image of a specimen at high speed and with high resolution.

  One embodiment of the present invention is an image acquisition device that acquires image data of a slide, and includes a first imaging unit, a first holding mechanism, and a second holding mechanism, and is held by the second holding mechanism. A second image pickup unit that picks up an image of the slide, a slide storage unit in which a plurality of slides are stored, and a control unit. The control unit slides from the slide storage unit by the first holding mechanism. The slide is transported to a predetermined position of the first image pickup unit, the slide of the slide held by the first holding mechanism is picked up by the first image pickup unit, and the first holding mechanism The slide is transported to the second holding mechanism, the position of the slide is adjusted by the second holding mechanism, and the image of the slide held by the second holding mechanism by the second imaging unit is captured. I do Implementing control, characterized in that.

  ADVANTAGE OF THE INVENTION According to this invention, the small-scale image acquisition apparatus which can acquire the image of a sample at high speed and high resolution can be provided.

FIG. 1 is a schematic diagram of an image acquisition apparatus according to an embodiment. FIG. 2 is a schematic view of a slide (observation target) in one embodiment. FIG. 3 is a schematic view of a first holding mechanism in one embodiment. FIG. 4 is a conceptual diagram of a first positioning mechanism in one embodiment. FIG. 5 is another conceptual diagram of the first positioning mechanism in the embodiment. FIG. 6 is a schematic view of a second holding mechanism in one embodiment. FIG. 7 is a conceptual diagram of a second positioning mechanism in one embodiment. FIG. 8 is an operation flowchart of the image acquisition apparatus according to the embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the description of this embodiment, a digital microscope is presented as an image acquisition apparatus and a slide is presented as a more preferable example as an image acquisition target, but the present invention is not limited to these. Further, numerical values exemplified for embodying the description are not limited to these unless otherwise specified. In addition, in each figure, the same reference number is attached | subjected about the same member and the overlapping description is abbreviate | omitted.

  An image acquisition apparatus according to an embodiment of the present invention will be described with reference to FIG. FIG. 1 is a diagram of an image acquisition apparatus 1000 that is a first embodiment for realizing the present invention. In the following description, the Z direction is defined as the optical axis direction of the imaging optical system that is an optical system, and the XY direction is defined as the direction perpendicular to the optical axis.

  The image acquisition apparatus 1000 is an apparatus for capturing an optical image of the slide 2 as a subject at a high magnification and acquiring a high-definition digital image. The image acquisition device 1000 transmits the acquired digital image to an image processing device (computer) (not shown), displays it on a display device, or stores it in a storage device. An imaging system can be configured by combining the imaging device (image acquisition device) and the image processing device (further, a display device or a storage device). Note that the configuration of the imaging device is not limited to this example, and for example, all or part of the functions of the image processing device, the storage device, the display device, and the like may be mounted on the imaging device.

  The image acquisition apparatus 1000 shown in FIG. 1 generally includes a slide carry-out unit 10, a first imaging unit 11, a second imaging unit 12, and a control unit 13.

  The slide carry-out unit 10 includes a slide storage unit 101 and a first holding mechanism 102. A plurality of slides are stored in the slide storage unit 101. The first holding mechanism 102 grips and unloads the slide 2 stored in the slide storage unit 101, and transfers it to the first imaging unit 11.

  The first imaging unit 11 acquires an image used for specifying an area where the specimen 21 (target object to be imaged) exists from the entire area of the slide 2 as a subject. As illustrated in FIG. 1, the first imaging unit 11 includes a first camera (first imaging unit) 111. The first camera 111 is preferably capable of photographing a wider range than the second camera 123 of the second imaging unit 12 described later, and has a field angle capable of photographing at least the entire area of the cover glass of the slide 2. preferable. Further, the first camera 111 may have a lower resolution (lower resolution) than the second camera. The first camera 111 captures a wide range of images of the slide 2 held by the first holding mechanism 102. Hereinafter, wide-area shooting by the first imaging unit 11 is referred to as macro shooting.

In this way, by performing macro imaging of the slide 2 in the first imaging unit 11, it is possible to grasp in advance the area where the specimen 21 of the slide 2 exists prior to imaging by the second imaging unit 12. . An image of the entire area of the slide 2 photographed by the first camera 111 is transmitted to the control unit 13 as slide macro imaging information 22.

  FIG. 2 is a diagram for explaining the existence area A of the specimen 21 to be observed on the slide 2. As shown in FIG. 2, when the existence area A is defined by a rectangle, the coordinate values X1, X2, Y1, and Y2 are controlled based on the slide macro imaging information 22 acquired by the first camera 111. The existence area A of the specimen 21 can be determined by obtaining in the unit 13. In the image acquisition apparatus according to the present embodiment, the lower right corner of the slide is defined as the slide origin 23 as shown in the figure. On the slide 2, a label 24 on which information necessary for managing the slide, such as a slide identification number and a cover glass thickness, is recorded may be attached. Examples of the label 24 include a one-dimensional barcode and a two-dimensional barcode.

  The second imaging unit 12 includes an illumination unit 121 that illuminates the slide 2 that is a subject, an imaging optical system 122 that forms an image of the slide 2, and a second camera that captures the image of the slide 2 (second imaging). Means) 123 and a second holding mechanism 124 on which the slide 2 is placed. The second holding mechanism 124 has a function of holding and moving the slide 2. After completion of imaging in the first imaging unit 11, the slide 2 is transferred to the second imaging unit 12 by the first holding mechanism 102 and placed on the second holding mechanism 124. The second holding mechanism 124 includes a placement unit 1242 that holds the slide 2, an XY stage 1243 that moves the placement unit 1242 in the X direction and the Y direction, and a Z stage 1244 that moves the placement unit 1242 in the Z direction. It is configured. The XY stage 1243 and the Z stage 1244 are provided with openings for allowing light from the illumination unit 121 to pass through. The second imaging unit 12 captures a narrow range for obtaining detailed information about the specimen 21 with high resolution. Hereinafter, photographing by the second imaging unit 12 (second camera) is referred to as micro imaging. Here, it is desirable that the image captured by the imaging optical system 122 and the second camera 123 has a higher resolution than the image captured by the first imaging unit 11.

  The control unit 13 includes a microprocessor (arithmetic unit) and a program, and controls the overall operation of the image acquisition apparatus 1000. The control unit 13 may be configured by an FPGA (Field Programmable Gate Array) or an ASIC (Application Specific Integrated Circuit). The control unit 13 takes out and conveys the slide 2 by the first holding mechanism 102, positioning processing of the first holding mechanism 102 and the second holding mechanism 124, and imaging processing by the first imaging unit 11 and the second imaging unit 12. A command to perform is output. Further, the control unit 13 sends an imaging command to the second camera 123 so that only the presence area A where the specimen 21 of the slide 2 is present is imaged by the second imaging unit 12, and a drive command to the second holding mechanism 124. Send. Thereby, imaging with respect to areas other than the existence area A of the specimen 21 can be omitted, and the processing time can be shortened.

  FIG. 3 is a schematic diagram relating to the first holding mechanism 102. The first holding mechanism 102 grips / unloads the slide 2 stored in the slide storage unit 101 and conveys the slide 2 to the first imaging unit 11. Macro imaging by the first imaging unit 11 is performed in a state where the first holding mechanism 102 holds the slide 2. Then, after the macro imaging is finished, the first holding mechanism 102 conveys the slide 2 to the second holding mechanism 124 in the second imaging unit 12. The series of operations described above is the role of the first holding mechanism 102.

The first holding mechanism 102 includes a first positioning mechanism 3, a gripping part 1021, a gripping drive part 1022 for driving the gripping part 1021, a first gripping part moving part 1023, a second gripping part moving part 1024, and a third gripping part moving part 1025. The first gripping unit moving unit 1023 moves the gripping drive unit 1022. The second gripping unit moving unit 1024 moves the first gripping unit moving unit 1023. The third gripping unit moving unit 1025 moves the second gripping unit moving unit 1024. here,
It is desirable that the first gripper moving unit 1023, the second gripper moving unit 1024, and the third gripper moving unit 1025 have orthogonal drive axes.

  The first holding mechanism 102 holds the slide 2 stored in the slide storage unit 101 by the first positioning mechanism 3, the holding unit 1021 and the holding drive unit 1022. Thereafter, the slide 2 is carried out of the slide storage unit 101 by driving the first gripping unit moving unit 1023. After unloading, the first holding mechanism 102 moves the slide 2 to a desired position by driving the first gripper moving unit 1023, the second gripper moving unit 1024, and the third gripper moving unit 1025, respectively. The first gripper moving unit 1023, the second gripper moving unit 1024, and the third gripper moving unit 1025 need to move over the entire area of the apparatus, and therefore require a large stroke of 500 mm to 800 mm. . As for positioning accuracy, low accuracy is sufficient, for example, accuracy of ± 5 μm to ± 10 μm. Specifically, as an example, a general linear motion system in which a drive source is a stepping motor and a ball screw is attached to the output shaft can be applied.

  FIG. 4 is a conceptual diagram regarding the first positioning mechanism 3 in the first holding mechanism 102. As shown in the drawing, the first holding mechanism 102 includes a first positioning mechanism 3. The first positioning mechanism 3 has a structure that positions the slide 2 at three points. As shown in the figure, the first positioning mechanism 3 includes an L-shaped member composed of a long side portion and a short side portion, and includes two semicircular portions (contact portions) on the long side portion, One semicircular part (contact part) is provided in the short side part orthogonal to. By holding the slide 2 in a state in which two semicircular portions abut on the long side direction of the slide 2 and one semicircular portion abuts on the short side direction, stable holding is possible. The reference line 31 shown in the figure is a straight line that touches both of the two semicircular portions of the long side portion described above. Further, the reference line 32 is a straight line that is in contact with one semicircular portion of the short side portion and is orthogonal to the reference line 31. The intersection of the reference line 31 and the reference line 32 is defined as a first positioning reference point 1020.

  The first holding mechanism 102 is moved in the direction of the arrow a so that the two adjacent side surfaces are in contact with the three points of the semicircular portion described above with respect to the slide 2 stored in the slide storage unit 101, and then gripped The part 1021 is moved in the direction of arrow b. Thereby, the slide 2 is held by the first positioning mechanism 3 and the grip portion 1021, and the first positioning reference point 1020 and the slide origin 23 coincide with each other. The first holding mechanism 102 performs positioning so that the first positioning reference point 1020 coincides with the coordinate origin of the first imaging unit 11 while holding the slide 2. As a result of positioning, the slide origin 23 coincides with the coordinate origin of the first imaging unit 11.

  FIG. 5 is a conceptual diagram of another embodiment relating to the first positioning mechanism 3 in the first holding mechanism 102. In the configuration of FIG. 5, a slide installation unit 33 is added to the configuration of FIG. 4. The slide installation part 33 has a thin plate shape that supports the edge of the long side of the slide 3. Further, as shown in the AA sectional view of the figure, the semicircular portion (contact view) in the first positioning mechanism 3 and the sliding contact portion in the grip portion 1021 are tapered (reference numerals 35 and 36). ). By adopting such a tapered shape, a force can be applied not only to the side surface direction but also to the installation surface direction with respect to the slide 2, and stable holding can be realized.

  FIG. 6 is a schematic view relating to the second holding mechanism 124. The second holding mechanism 124 includes a placement portion 1242 for placing the slide 2, a second positioning mechanism 4, a slide fixing portion 1241, an XY stage 1243, and a Z stage 1244. The XY stage 1243 moves the placement unit 1242 in the X direction and the Y direction. The Z stage 1244 moves the placement unit 1242 in the Z direction.

The XY stage 1243 is required to be able to move the entire range of the specimen presence area A on the slide 2. Here, since there is a possibility that the specimen existing area A may be the entire area of the slide 2, the XY stage 1243 is required to be able to move at least 76 mm × 26 mm, which is the entire area of the slide 2. In addition, since high-resolution micro imaging is performed, positioning accuracy of ± 0.1 μm or less is required. For example, the XY stage 1243 has a configuration in which an ultrasonic motor is used as a drive source to drive a movable part installed on a linear guide, and the amount of movement of the movable part is measured by a linear encoder (resolution 10 nm), and feedback control is applied. desirable.

  The Z stage 1244 is a stage for scanning in the Z direction that is the optical axis direction in the specimen existing area A, and a moving distance of 150 μm to 200 μm that is the specimen existing area in the Z direction is required. The positioning accuracy is required to be ± 10 nm or less in order to perform micro imaging using the imaging optical system 122 having a high NA (numerical aperture). For example, the Z stage 1244 preferably has a configuration in which a movable part is moved using a piezo element as a displacement magnifying mechanism, and a configuration in which a movement amount is measured by a capacitance sensor (resolution: 1 nm) and feedback control is applied.

  FIG. 7 is a conceptual diagram regarding the second positioning mechanism 4 in the second holding mechanism 124. As shown in the figure, the second holding mechanism 124 includes the second positioning mechanism 4. Similar to the first positioning mechanism 3, the second positioning mechanism 4 has a structure that positions the slide 2 at three points. As shown in the drawing, the second positioning mechanism 4 includes an L-shaped member composed of a long side portion and a short side portion, and includes two semicircular portions (contact portions) on the long side portion, One semicircular part (contact part) is provided in the short side part orthogonal to. By holding the slide 2 in a state in which two semicircular portions abut on the long side direction of the slide 2 and one semicircular portion abuts on the short side direction, stable holding is possible. The reference line 41 shown in the figure is a straight line that touches both of the two semicircular portions of the long side portion described above. The reference line 42 is a straight line that is in contact with one semicircular portion of the short side portion and is orthogonal to the reference line 41. The intersection of the reference line 41 and the reference line 42 is defined as a second positioning reference point 1240.

  Similarly to the second positioning mechanism 4, the slide fixing portion 1241 has an L-shaped shape composed of a long side portion and a short side portion, and the long side portion and the short side portion are respectively the second positioning mechanism 4. It arrange | positions so that the long side part and short side part of this may be opposed. When the slide fixing portion 1241 moves relative to the second positioning mechanism 4, the four sides of the slide 2 are firmly held (fixed) by the slide fixing portion 1241 and the second positioning mechanism 4.

  The first holding mechanism 103 moves to the second imaging unit 12 while holding the slide 2 and places the slide on the second holding mechanism 124. The slide fixing portion 1241 moves in the direction of the arrow d so that the two adjacent side surfaces are in contact with the three points of the semicircular portion described above with respect to the placed slide 2. The arrow d is in a direction parallel to the arrow c which is a linear direction connecting the second positioning reference point 1240 and the slide origin 23. By holding as such, the second positioning reference point 1240 and the slide origin 23 coincide.

  The XY stage 1243 provided in the second holding mechanism 124 performs positioning so that the second positioning reference point 1240 coincides with the coordinate system origin of the second imaging unit 12 while holding the slide 2. As a result of the positioning, the slide origin 23 coincides with the coordinate system origin of the second imaging unit 12.

  As with the first holding mechanism 102 shown in FIG. 5, the second holding mechanism 124 also has a semicircular portion (contact portion) in the second positioning mechanism 4 and a sliding contact in the slide fixing portion 1241. The portion can be tapered. By adopting such a tapered shape, a force can be applied not only to the side surface direction but also to the installation surface direction with respect to the slide 2, and stable holding can be realized.

  As described above, in the present embodiment, the first positioning mechanism 3 matches the coordinate origin of the first imaging unit 11 and the slide origin 23, and the second positioning mechanism 4 sets the coordinate origin of the second imaging unit 12. The slide origin 23 is matched. By positioning as such, the coordinate origin of the first imaging unit 11 and the coordinate origin of the second imaging unit 12 coincide. As a result, the coordinate system of the image acquired by the macro imaging performed by the first imaging unit 11 matches the coordinate system of the image acquired by the micro imaging performed by the second imaging unit 12. The coordinate origin coincidence accuracy at this time can be realized to be ± 0.2 mm or less in consideration of the positioning accuracy of the first holding mechanism 102 and the contact accuracy of the first positioning mechanism 3 and the second positioning mechanism 4. . By matching the coordinate systems of the two images in this way, erroneous imaging due to the mismatch between the macro imaging and micro imaging coordinate systems (images of locations that are different from the locations that should be viewed or images that cannot be captured may occur. Etc.) can be avoided.

  FIG. 8 is a flowchart showing the operation of the image acquisition apparatus 1000. The operation of the image acquisition apparatus 1000 will be described with reference to FIG. First, in step S <b> 1, the first holding mechanism 102 takes out the slide 2 from the slide storage unit 101 based on a transfer command 130 from the control unit 13 and transfers it to a predetermined position of the first imaging unit 11. This predetermined position is a position where the first imaging unit 11 can image the entire slide 2. In step S <b> 2, the first camera 111 performs macro imaging of the slide 2 (imaging of the entire slide) based on the imaging command 131 from the control unit 13.

  In step S <b> 3, the control unit 13 detects an area where the specimen 21 exists from the slide macro imaging information 22 by image analysis, and specifies the existing area A. In general, the portion of the specimen 21 on the slide 2 and the other background portions are significantly different in luminance and color. Therefore, the portion of the specimen 21 can be detected using known image analysis processing such as binarization, feature amount extraction, and contour detection.

  When the identification of the existence area A is completed, in step S4, the first holding mechanism 102 places the slide 2 on the second holding mechanism 124 of the second imaging unit 12 based on the transfer command 132 from the control unit 13. . In step S <b> 5, the second camera 123 performs micro imaging of the slide based on the imaging command 133 from the control unit 13 and acquires a digital image. In micro imaging, the specimen 21 is imaged with high resolution. The shooting command 133 is a command for adjusting the existence area A (observation area) to be within the shooting range of the second camera 123 with respect to the XY stage 1243 provided in the second holding mechanism 124 and the second camera 123. And imaging command. When the observation area is wide, it is not possible to image all the observation areas with a single micro imaging. In step S6, the control unit 13 determines whether imaging of the entire existing area A has been completed. If the entire present area A has not been imaged (S6-NO), the process proceeds to step S7, and the XY stage 1243 provided in the second holding mechanism 124 moves the slide 2 based on the imaging command 134 from the control unit 13. Move to the next imaging position. The process returns to step S5, and imaging is performed again. S5, S6, and S7 are repeated until the entire imaging of the existing area A is completed.

  As described above, according to the configuration of the present embodiment, by performing macro imaging with the first camera 111, an area in which the specimen 21 of the slide 2 exists is preliminarily prior to imaging with the second imaging unit 12. To be able to grasp. Thereby, since it is possible to omit the imaging for the area where the specimen 21 does not exist, the imaging processing time can be shortened.

In addition, the transport and positioning of the slide 2 are separated into the first holding mechanism 102 and the second holding mechanism 124. The first holding mechanism 102 performs positioning in macro imaging and transport to the second holding mechanism 124, and the second holding mechanism. The mechanism 124 performs highly accurate positioning in micro imaging. As described above, the image acquisition apparatus 1000 according to the present embodiment has the first holding mechanism 102 having a relatively low positioning accuracy but a large required movement amount, and a small required movement amount but a required positioning accuracy. And a high second holding mechanism 124. If both are realized in one stage, the stage itself becomes large-scale, but it can be realized in a small-scale apparatus by separating each stage separately. Therefore, according to the present embodiment, an image acquisition apparatus that can acquire an image of a specimen at high speed and high resolution can be reduced in size (miniaturized).

(Other examples)
The present invention supplies a program that realizes one or more functions of the above-described embodiments to a system or apparatus via a network or a storage medium, and one or more processors in a computer of the system or apparatus read and execute the program This process can be realized. It can also be realized by a circuit (for example, ASIC) that realizes one or more functions.

1000 Image acquisition device 10 Slide unloading unit 11 First imaging unit 12 Second imaging unit 13 Control unit 102 First holding mechanism 124 Second holding mechanism

Claims (10)

An image acquisition device for acquiring image data of a slide,
A first imaging unit;
A first holding mechanism;
A second imaging unit that has a second holding mechanism and images a slide held by the second holding mechanism;
A slide storage section in which a plurality of slides are stored;
A control unit;
With
The controller is
The first holding mechanism takes out the slide from the slide storage unit, conveys the slide to a predetermined position of the first imaging unit,
The first imaging unit performs imaging of the slide held in the first holding mechanism,
The first holding mechanism conveys the slide to the second holding mechanism,
The second holding mechanism adjusts the position of the slide,
The second imaging unit performs imaging of the slide held by the second holding mechanism.
Implement control,
An image acquisition apparatus characterized by that. The movement amount of the first holding mechanism is larger than the movement amount of the second holding mechanism,
The positioning accuracy of the second holding mechanism is higher than the positioning accuracy of the first holding mechanism.
The image acquisition apparatus according to claim 1. The first holding mechanism has a first positioning mechanism that positions the slide origin of the slide and the coordinate origin of the first imaging unit,
The second holding mechanism has a second positioning mechanism that positions the slide origin of the slide and the coordinate origin of the second imaging unit,
The image acquisition device according to claim 1. The first positioning mechanism and the second positioning mechanism are configured to determine the position of the slide using the same position of the slide as the slide origin.
The image acquisition device according to claim 3. The first positioning mechanism includes an L-shaped member composed of a long side portion and a short side portion, two contact portions that come into contact with the slide on the long side portion, and a slide on the short side portion. One abutment is provided,
The first holding mechanism further includes a grip portion that grips the slide together with the long side portion.
The image acquisition device according to claim 3 or 4. At least one of the three contact portions of the first positioning mechanism and the contact portion between the slide of the grip portion has a tapered shape.
The image acquisition apparatus according to claim 5. The second positioning mechanism includes an L-shaped member composed of a long side portion and a short side portion, two contact portions that come into contact with the slide on the long side portion, and a slide on the short side portion. One abutment is provided,
The second holding mechanism is an L-shaped fixing portion including a long side portion and a short side portion, and further includes a fixing portion that holds the four sides of the slide together with the second positioning mechanism.
The image acquisition device according to claim 3. At least one of the three contact portions of the second positioning mechanism and the contact portion of the fixed portion with the slide has a tapered shape.
The image acquisition device according to claim 7. The first imaging unit captures a wider range than the second imaging unit,
The second imaging unit has a higher resolution than the first imaging unit,
The control unit determines an observation area of the slide from an image captured by the first imaging unit, and the second holding mechanism causes the observation area to be positioned in an imaging range of the second imaging unit. Adjusting the position of the slide,
The image acquisition device according to claim 1. The control unit detects an area where the specimen on the slide is present by image analysis, and determines that the area is the observation area.
The image acquisition device according to claim 9.

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