A method and apparatus for determining the actual center of a defocused concentric circle image in visual measurement.

Abstract

This invention provides a method and apparatus for determining the actual center of a defocused concentric circle image in visual measurement. The method includes: acquiring a defocused image of a concentric circle marker image after perspective projection transformation, and determining the center point information of the inner and outer ellipses of the defocused image; determining the expressions of a first line, a second line, and a third line based on the center point information of the inner and outer ellipses; calculating the target intersection point information of the first line and the third line, whereby the target intersection point is the actual center of the defocused image. This invention, based on the properties of projection transformation, uses geometric methods to quickly and accurately obtain the actual center of the defocused image of a concentric circle marker after perspective projection transformation, and extracts the feature points of the actual center, thereby improving the accuracy of visual measurement.

Description

Technical Field

[0001] This invention relates to the field of visual inspection technology, specifically to a method and apparatus for determining the actual center of a defocused concentric circle image in visual measurement. Background Technology

[0002] With the rapid development of computer vision measurement technology and the reduction in the cost of supporting equipment and facilities, computer vision measurement technology has been widely applied in many fields. Currently, computer vision technology is being used to measure ultra-large structures; however, due to the long shooting distance, the captured images often exhibit defocusing, leading to blurred images and inaccurate positioning, affecting the final measurement results. To improve the contrast of the measured points, the main features currently used include artificial and natural markers. Among them, artificial markers can achieve better contrast. Therefore, in high-precision visual measurement processes, artificial markers remain the primary method. The most commonly used artificial markers include cross-shaped markers, artificial speckle patterns, and circular markers.

[0003] In existing technologies, cross-shaped markers are difficult to locate precisely due to the arbitrary generation of tic-tac-toe intersections during edge detection; artificial speckle is mainly used in digital image correlation calculations, which involve a large computational load; while circular markers are widely used due to their rotation invariance and ease of feature point extraction. However, since the image of a circular marker becomes elliptical after perspective projection transformation, and current methods for extracting the center of the marker still use the geometric center of the ellipse as the feature point, this is, as we know, inaccurate. This problem limits the improvement of the accuracy of computer vision measurement, thereby reducing the universality of visual measurement.

[0004] In summary, existing technologies suffer from inaccurate positioning of the actual center of defocused images in visual measurement, resulting in low accuracy in actual visual measurements. Summary of the Invention

[0005] In view of this, it is necessary to provide a method and apparatus for determining the actual center of a defocused concentric circle image in visual measurement, so as to solve the technical problem that the inaccurate positioning of the actual center of the defocused image in the prior art leads to low accuracy of actual visual measurement.

[0006] On one hand, the present invention provides a method for determining the actual center of a defocused concentric circle image in visual measurement, comprising:

[0007] Obtain the defocused image of the concentric circle marker image after perspective projection transformation, and determine the information of the inner and outer elliptical center points of the defocused image;

[0008] The expressions for the first, second, and third straight lines are determined based on the information of the center points of the inner and outer ellipses;

[0009] Calculate the target intersection point information of the first line and the third line, and the target intersection point is the actual center of the defocused image;

[0010] Wherein, the first straight line is a straight line passing through the center points of the inner and outer ellipses, the second straight line is parallel to the first straight line and the distance between the second straight line and the first straight line is half the length of the minor axis of the inner ellipse, and it intersects the inner and outer ellipses at two points, the third straight line is a straight line passing through the intersection points of the two tangents of the inner ellipse and the two tangents of the outer ellipse, the two tangents of the inner ellipse are the straight lines passing through the two intersection points of the second straight line and the inner ellipse, and the two tangents of the outer ellipse are the straight lines passing through the two intersection points of the second straight line and the outer ellipse.

[0011] In some possible implementations, obtaining the defocused image of the concentric circle marker image after perspective projection transformation, and determining the inner and outer elliptical center point information of the defocused image, includes:

[0012] The concentric circle logo image is subjected to contrast enhancement processing to reduce the blurriness of the out-of-focus image after perspective projection transformation.

[0013] Subpixel edge extraction is performed on the defocused image, and the ellipse is fitted using the least squares method to obtain the centers of the fitted inner and outer ellipses.

[0014] In some possible implementations, the expression for determining the first, second, and third straight lines based on the information of the inner and outer ellipse centers includes:

[0015] The expression for the first straight line is determined based on the two centers of the inner and outer elliptical images;

[0016] The expression of the second line is determined based on the expression of the first line, and the intersection information of the second line with the inner and outer ellipses is obtained.

[0017] Based on the intersection information of the second straight line with the inner and outer ellipses, the intersection information of the inner ellipse tangents and the intersection information of the outer ellipse tangents passing through the intersection points are determined;

[0018] The expression for the third line is determined based on the intersection information of the inner ellipse tangents and the intersection information of the outer ellipse tangents.

[0019] In some possible implementations, the expression for determining the first straight line based on the two centers of the inner and outer elliptical images includes:

[0020] The coordinates of the centers of the inner and outer ellipses of the defocused image, as well as the length of the minor axis radius of the inner ellipse, are obtained respectively, and the first straight line passing through the centers of the inner and outer ellipses is determined.

[0021] According to the principle of projection transformation, the actual center of the defocused image marker is on the first straight line.

[0022] In some possible implementations, determining the expression of the second line based on the expression of the first line, and the intersection information of the second line with the inner and outer ellipses, includes:

[0023] Draw a second line parallel to the first line and at a distance from the first line that is half the length of the minor axis of the inner ellipse. Determine the expression of the second line, wherein the second line intersects both the inner and outer ellipses at two points.

[0024] Obtain the coordinates of the two inner intersection points of the second line with the inner ellipse, and the coordinates of the two outer intersection points of the second line with the outer ellipse.

[0025] In some possible implementations, determining the intersection point information of the inner ellipse tangents and the outer ellipse tangents passing through the intersection points based on the intersection point information of the second straight line and the inner and outer ellipses includes:

[0026] Draw tangents to the inner ellipse through the two inner intersection points and obtain the coordinates of the intersection of the two tangents of the inner ellipse. Draw tangents to the outer ellipse through the two outer intersection points and obtain the coordinates of the intersection of the tangents of the outer ellipse.

[0027] In some possible implementations, the expression for determining the third line based on the intersection information of the inner ellipse tangents and the intersection information of the outer ellipse tangents includes:

[0028] Based on the coordinates of the intersection point of the inner ellipse tangent and the coordinates of the intersection point of the outer ellipse tangent, a third straight line passing through the intersection point of the inner ellipse tangent and the intersection point of the outer ellipse tangent is obtained, and the expression of the third straight line is determined.

[0029] According to the principle of projection transformation, the actual center of the defocused image mark is on the third straight line, and the third straight line intersects with the first straight line.

[0030] In some possible implementations, calculating the target intersection point information of the first and third lines, where the target intersection point is the actual center of the defocused image, includes:

[0031] Calculate the coordinates of the target intersection point of the first line and the third line based on their expressions.

[0032] According to the principle of projection transformation, the coordinates of the target intersection point are the actual center position of the defocused image marker.

[0033] On the other hand, the present invention provides a device for determining the actual center of a defocused concentric circle image in visual measurement, comprising:

[0034] The data acquisition module is used to acquire the defocused image of the concentric circle marker image after perspective projection transformation, and to determine the information of the inner and outer elliptical center points of the defocused image;

[0035] The data processing module is used to determine the expressions of the first line, the second line, and the third line based on the information of the center points of the inner and outer ellipses;

[0036] The determination module calculates the target intersection point information of the first line and the third line, and the target intersection point is the actual center of the defocused image.

[0037] The present invention also provides an electronic device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the processor executes the program, it implements the method for determining the actual center of a defocused concentric circle image in visual measurement as described in the above implementation.

[0038] The beneficial effects of the above embodiments are: the method for determining the actual center of a defocused concentric circle image in visual measurement provided by the present invention can quickly and accurately obtain the actual center of the defocused image of the concentric circle artificial marker after perspective projection transformation through geometric methods based on the properties of projection transformation, and extract the feature points of the actual center, thereby improving the accuracy of visual measurement. Attached Figure Description

[0039] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0040] Figure 1 A schematic flowchart of an embodiment of the method for determining the actual center of a defocused concentric circle image in visual measurement provided by the present invention;

[0041] Figure 2 Provided by the present invention Figure 1 A flowchart illustrating an embodiment of step S101;

[0042] Figure 3 This is a schematic diagram of the structure of an embodiment of the concentric circle artificial marker provided by the present invention;

[0043] Figure 4 Provided by the present invention Figure 1 A flowchart illustrating an embodiment of step S102;

[0044] Figure 5 A schematic diagram of an embodiment of concentric circle perspective transformation provided by the present invention;

[0045] Figure 6 A schematic diagram of the structure of an embodiment of the fitted ellipse provided by the present invention;

[0046] Figure 7 A schematic diagram of an embodiment of the device for determining the actual center of a defocused concentric circle image in visual measurement provided by the present invention;

[0047] Figure 8 A schematic diagram of an embodiment of the electronic device provided by the present invention. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0049] It should be understood that the illustrative drawings are not drawn to scale. The flowcharts used in this invention illustrate operations implemented according to some embodiments of the invention. It should be understood that the operations in the flowcharts may not be implemented in sequence, and steps without logical contextual relationships may be reversed or performed simultaneously. Furthermore, those skilled in the art, guided by the content of this invention, may add one or more other operations to the flowcharts, or remove one or more operations from the flowcharts.

[0050] Some of the block diagrams shown in the accompanying drawings are functional entities and do not necessarily correspond to physically or logically independent entities. These functional entities can be implemented in software, in one or more hardware modules or integrated circuits, or in different network and / or processor systems and / or microcontroller systems.

[0051] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of the invention. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0052] This invention provides a method and apparatus for determining the actual center of a defocused concentric circle image in visual measurement, which will be described below.

[0053] Figure 1This is a schematic flowchart of an embodiment of the method for determining the actual center of a defocused concentric circle image in visual measurement provided by the present invention. The method for determining the actual center of a defocused concentric circle image in visual measurement includes:

[0054] S101. Obtain the defocused image of the concentric circle marker image after perspective projection transformation, and determine the information of the inner and outer elliptical center points of the defocused image.

[0055] S102. Determine the expressions for the first line, the second line, and the third line based on the information of the center points of the inner and outer ellipses;

[0056] S103. Calculate the target intersection point information of the first straight line and the third straight line. The target intersection point is the actual center of the defocused image.

[0057] Wherein, the first straight line is a straight line passing through the center points of the inner and outer ellipses, the second straight line is parallel to the first straight line and the distance between the second straight line and the first straight line is half the length of the minor axis of the inner ellipse, and it intersects the inner and outer ellipses at two points, the third straight line is a straight line passing through the intersection points of the two tangents of the inner ellipse and the two tangents of the outer ellipse, the two tangents of the inner ellipse are the straight lines passing through the two intersection points of the second straight line and the inner ellipse, and the two tangents of the outer ellipse are the straight lines passing through the two intersection points of the second straight line and the outer ellipse.

[0058] Compared with the prior art, the method for determining the actual center of a defocused concentric circle image in visual measurement provided by the embodiments of the present invention uses a geometric method to determine the actual center position of the defocused image. On the one hand, this makes the extraction of image center feature points more accurate, improving the accuracy of visual measurement in practical applications. On the other hand, it simplifies the calculation process, improving the efficiency of visual measurement in practical applications.

[0059] In some embodiments of the present invention, such as Figure 2 As shown, Figure 2 Provided by the present invention Figure 1 A flowchart of one embodiment of step S101 includes:

[0060] S201. Perform contrast enhancement processing on the concentric circle marker image to reduce the blurriness of the out-of-focus image after perspective projection transformation.

[0061] S202. Perform subpixel edge extraction on the defocused image and fit an ellipse using the least squares method to obtain the center of the fitted inner and outer ellipse.

[0062] In a specific embodiment of the present invention, a concentric circle artificial marker is created, which consists of an inner circle and an outer circle. (See [link to relevant documentation]). Figure 3 , Figure 3This is a schematic diagram of an embodiment of the concentric circle artificial marker provided by the present invention. A defocused image of the artificial marker is captured, and an image contrast enhancement algorithm is used for preliminary image processing to enhance image contrast, reduce the impact of blurred images on the results, and fit an ellipse to obtain two ellipses. Due to the influence of perspective projection transformation, shooting shake, and camera distortion, the centers of the obtained ellipses are generally not the same point. The centers of the ellipses are set as follows: p m p n .

[0063] Furthermore, in some embodiments of the present invention, such as Figure 4 As shown, Figure 4 Provided by the present invention Figure 1 A flowchart of one embodiment of step S102 includes:

[0064] S401. Determine the expression for the first straight line based on the two centers of the inner and outer elliptical images;

[0065] S402. Determine the expression of the second line based on the expression of the first line, and the intersection information of the second line with the inner and outer ellipses;

[0066] S403. Based on the intersection information of the second straight line with the inner and outer ellipses, determine the intersection information of the inner ellipse tangents and the outer ellipse tangents passing through the intersection points;

[0067] S404. Determine the expression of the third straight line based on the intersection information of the inner ellipse tangents and the intersection information of the outer ellipse tangents;

[0068] In some embodiments of the present invention, the coordinates of the centers of the inner and outer ellipses of the defocused image, and the length of the minor axis radius of the inner ellipse are obtained respectively, and a first straight line passing through the centers of the inner and outer ellipses is determined.

[0069] According to the principle of projection transformation, the actual center of the defocused image marker is on the first straight line.

[0070] To better understand the principles of projection transformation, please refer to [link / reference needed]. Figure 5 , Figure 5 This is a schematic diagram of an embodiment of concentric circle perspective transformation provided by the present invention.

[0071] Draw a second line parallel to the first line and at a distance from the first line that is half the length of the minor axis of the inner ellipse. Determine the expression of the second line, wherein the second line intersects both the inner and outer ellipses at two points.

[0072] Obtain the coordinates of the two inner intersection points of the second line with the inner ellipse, and the coordinates of the two outer intersection points of the second line with the outer ellipse.

[0073] Draw tangents to the inner ellipse through the two inner intersection points and obtain the coordinates of the intersection of the two tangents of the inner ellipse. Draw tangents to the outer ellipse through the two outer intersection points and obtain the coordinates of the intersection of the tangents of the outer ellipse.

[0074] Based on the coordinates of the intersection point of the inner ellipse tangent and the coordinates of the intersection point of the outer ellipse tangent, a third straight line passing through the intersection point of the inner ellipse tangent and the intersection point of the outer ellipse tangent is obtained, and the expression of the third straight line is determined.

[0075] According to the principle of projection transformation, the actual center of the defocused image mark is on the third straight line, and the third straight line intersects with the first straight line.

[0076] In a specific embodiment of the present invention, the calculation is performed that the points p pass through two center points simultaneously. m p n The straight line L1, as shown Figure 6 As shown, Figure 6 This is a schematic diagram of a fitting ellipse according to an embodiment of the present invention. According to the principle of projection transformation, the actual center of the circular mark is on the straight line L1.

[0077] Draw a straight line L2 that is parallel to line L1 and is at a distance from L1 that is half the length of the minor axis of the inner circle;

[0078] Line L2 intersects the inner and outer circles at point p. Ii p Ii ′、p Io p Io ′;

[0079] Draw points p respectively Ii p Ii ′、p Io p Io The inner and outer circles of the circle are tangents to each other, and the intersection points are P1 and P2.

[0080] Draw a straight line L3 passing through points P1 and P2. According to the principle of perspective transformation, the actual center of the ellipse lies on the straight line L3.

[0081] Furthermore, in some embodiments of the present invention, step S103 includes: calculating the coordinates of the target intersection point of the first line and the third line according to the expressions of the first line and the third line;

[0082] According to the principle of projection transformation, the coordinates of the target intersection point are the actual center position of the defocused image marker.

[0083] In the specific embodiments of the present invention, please refer again. Figure 6 Calculate the intersection point of line L1 and line L3. This intersection point is the actual center of the circular mark after projection transformation.

[0084] It should be noted that, in order to improve the accuracy of extracting the actual center coordinates of the defocused image, steps S102 to S103 can be repeated multiple times, and the average value of the actual center coordinates can be used as the final actual center coordinate value.

[0085] The embodiments of the present invention can quickly and accurately obtain the actual center of the defocused image of the concentric circle artificial sign after perspective projection transformation by using geometric methods and the properties of graphic projection transformation, and extract the feature points of the actual center, thereby improving the accuracy of visual measurement.

[0086] To better implement the method for determining the actual center of a defocused concentric circle image in visual measurement according to the embodiments of the present invention, the embodiments of the present invention also provide a device for determining the actual center of a defocused concentric circle image in visual measurement, such as... Figure 7 As shown, the device 700 for determining the actual center of a defocused concentric circle image in visual measurement includes:

[0087] The data acquisition module 701 is used to acquire the defocused image of the concentric circle marker image after perspective projection transformation, and to determine the information of the inner and outer elliptical center points of the defocused image;

[0088] The data processing module 702 is used to determine the expressions of the first line, the second line, and the third line based on the information of the center points of the inner and outer ellipses;

[0089] The determination module 703 calculates the target intersection point information of the first line and the third line, and the target intersection point is the actual center of the defocused image.

[0090] The present invention also provides an electronic device 800, such as... Figure 8 As shown, the electronic device 800 includes a processor 801, a memory 802, and a display 803. Figure 8 Only some components of the electronic device 800 are shown, but it should be understood that it is not required to implement all the components shown, and more or fewer components may be implemented instead.

[0091] In some embodiments, processor 801 may be a central processing unit (CPU), a microprocessor, or other data processing chip, used to run program code stored in memory 802 or process data, such as the program for determining the actual center of a defocused concentric circle image in visual measurement in this invention.

[0092] In some embodiments, processor 801 may be a single server or a group of servers. The server group may be centralized or distributed. In some embodiments, processor 801 may be local or remote. In some embodiments, processor 801 may be implemented on a cloud platform. In one embodiment, the cloud platform may include a private cloud, public cloud, hybrid cloud, community cloud, distributed cloud, intranet, multi-cloud, etc., or any combination thereof.

[0093] In some embodiments, memory 802 may be an internal storage unit of electronic device 800, such as a hard disk or memory of electronic device 800. In other embodiments, memory 802 may also be an external storage device of electronic device 800, such as a plug-in hard disk, smart media card (SMC), secure digital (SD) card, flash card, etc. equipped on electronic device 800.

[0094] Furthermore, the memory 802 may include both internal storage units of the electronic device 800 and external storage devices. The memory 802 is used to store application software and various types of data installed on the electronic device 800.

[0095] In some embodiments, display 803 may be an LED display, a liquid crystal display, a touch-sensitive liquid crystal display, or an OLED (Organic Light-Emitting Diode) touchscreen. Display 803 is used to display information from electronic device 800 and to display a visual user interface. Components 801-803 of electronic device 800 communicate with each other via a system bus.

[0096] In one embodiment, when processor 801 executes the procedure for determining the actual center of a defocused concentric circle image in visual measurement stored in memory 802, the following steps can be implemented:

[0097] Obtain the defocused image of the concentric circle marker image after perspective projection transformation, and determine the information of the inner and outer elliptical center points of the defocused image;

[0098] The expressions for the first, second, and third straight lines are determined based on the information of the center points of the inner and outer ellipses;

[0099] Calculate the target intersection point information of the first line and the third line, and the target intersection point is the actual center of the defocused image;

[0100] Wherein, the first straight line is a straight line passing through the center points of the inner and outer ellipses, the second straight line is parallel to the first straight line and the distance between the second straight line and the first straight line is half the length of the minor axis of the inner ellipse, and it intersects the inner and outer ellipses at two points, the third straight line is a straight line passing through the intersection points of the two tangents of the inner ellipse and the two tangents of the outer ellipse, the two tangents of the inner ellipse are the straight lines passing through the two intersection points of the second straight line and the inner ellipse, and the two tangents of the outer ellipse are the straight lines passing through the two intersection points of the second straight line and the outer ellipse.

[0101] It should be understood that when the processor 801 executes the procedure for determining the actual center of the defocused concentric circle image in the visual measurement in the memory 802, in addition to the functions mentioned above, it can also perform other functions, as detailed in the description of the corresponding method embodiments above.

[0102] Furthermore, this embodiment of the invention does not specifically limit the type of electronic device 800 mentioned. Electronic device 800 can be a mobile phone, tablet computer, personal digital assistant (PDA), wearable device, laptop computer, or other portable electronic device. Exemplary embodiments of portable electronic devices include, but are not limited to, portable electronic devices running iOS, Android, Microsoft, or other operating systems. The aforementioned portable electronic device can also be other portable electronic devices, such as a laptop computer with a touch-sensitive surface (e.g., a touch panel). It should also be understood that in some other embodiments of the invention, electronic device 800 may not be a portable electronic device, but rather a desktop computer with a touch-sensitive surface (e.g., a touch panel).

[0103] Accordingly, this application also provides a computer-readable storage medium for storing a computer-readable program or instruction. When the program or instruction is executed by a processor, it can implement the steps in the method for determining the actual center of a defocused concentric circle image in visual measurement provided in the above-described method embodiments.

[0104] Those skilled in the art will understand that all or part of the processes of the methods described in the above embodiments can be implemented by a computer program instructing related hardware (such as a processor, controller, etc.), and the computer program can be stored in a computer-readable storage medium. The computer-readable storage medium may be a disk, optical disk, read-only memory, or random access memory, etc.

[0105] The above provides a detailed description of the method and apparatus for determining the actual center of a defocused concentric circle image in visual measurement provided by the present invention. Specific examples have been used to illustrate the principle and implementation of the present invention. The description of the above embodiments is only for the purpose of helping to understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, there will be changes in the specific implementation and application scope based on the idea of ​​the present invention. Therefore, the content of this specification should not be construed as a limitation of the present invention.

Claims

1. A method for determining the actual center of a defocused concentric circle image in visual measurement, characterized in that, The method comprises the following steps: obtaining an out-of-focus image of a concentric circle sign image after perspective projection transformation, and determining the inner and outer ellipse center point information of the out-of-focus image; determining the expressions of the first, second and third straight lines based on the inner and outer ellipse center point information; calculating the target intersection point information of the first and third straight lines, and the target intersection point is the actual center of the out-of-focus image; wherein the first straight line is a straight line passing through the inner and outer ellipse center points, the second straight line is parallel to the first straight line and the distance between the first straight line and the second straight line is half of the length of the inner ellipse short axis, and the second straight line has two intersection points with the inner and outer ellipses, and the third straight line is a straight line passing through the intersection points of the inner ellipse two tangent lines and the outer ellipse two tangent lines, the inner ellipse two tangent lines are straight lines passing through the two intersection points of the second straight line and the inner ellipse, and the outer ellipse two tangent lines are straight lines passing through the two intersection points of the second straight line and the outer ellipse.

2. The method according to claim 1, wherein, The method comprises the following steps: performing contrast enhancement processing on the concentric circle sign image to reduce the blurring degree of the out-of-focus image after perspective projection transformation; performing sub-pixel edge extraction on the out-of-focus image, and fitting ellipses by using the least square method to obtain the centers of the fitted inner and outer ellipses.

3. The method of claim 1, wherein, The method comprises the following steps: determining the expression of the first straight line based on the two centers of the inner and outer ellipse images; determining the expression of the second straight line based on the expression of the first straight line, and the intersection point information of the second straight line with the inner and outer ellipses; determining the inner ellipse tangent intersection point information and the outer ellipse tangent intersection point information of the inner and outer ellipse tangent lines passing through the intersection points based on the intersection point information of the second straight line with the inner and outer ellipses; determining the expression of the third straight line based on the inner ellipse tangent intersection point information and the outer ellipse tangent intersection point information.

4. The method of claim 3, wherein, The method comprises the following steps: obtaining the inner and outer ellipse center coordinates of the out-of-focus image, and the length of the inner ellipse short axis, and determining the first straight line passing through the inner and outer ellipse centers; According to the principle of projection transformation, the actual center of the out-of-focus image sign is on the first straight line.

5. The method of claim 3, wherein, The method comprises the following steps: drawing a second straight line parallel to the first straight line and having a distance of half the length of the inner ellipse short axis from the first straight line, determining the expression of the second straight line, wherein the second straight line has two intersection points with the inner and outer ellipses; obtaining the two inner intersection point coordinates of the second straight line with the inner ellipse, and the two outer intersection point coordinates of the second straight line with the outer ellipse.

6. The method of determining the actual center of a defocused concentric circle image in visual measurement according to claim 5, wherein, The method comprises the following steps: The two inner intersection points are used to draw tangent lines of the inner ellipse, and the intersection point coordinates of the two tangent lines of the inner ellipse are obtained; the two outer intersection points are used to draw tangent lines of the outer ellipse, and the intersection point coordinates of the two tangent lines of the outer ellipse are obtained.

7. The method of determining the actual center of a defocused concentric circle image in visual measurement according to claim 6, characterized in that, The expression of the third straight line is determined based on the intersection point information of the tangent lines of the inner ellipse and the intersection point information of the tangent lines of the outer ellipse. The third straight line passing through the intersection points of the tangent lines of the inner ellipse and the tangent lines of the outer ellipse is obtained based on the intersection point coordinates of the tangent lines of the inner ellipse and the intersection point coordinates of the tangent lines of the outer ellipse, and the expression of the third straight line is determined. According to the principle of projection transformation, the actual center of the out-of-focus image mark is on the third straight line, and the third straight line intersects the first straight line.

8. The method for determining the actual center of defocus concentric circle image in visual measurement according to claim 7, characterized in that, The target intersection point of the first straight line and the third straight line is calculated, and the target intersection point is the actual center of the out-of-focus image. The target intersection point coordinates of the first straight line and the third straight line are calculated according to the expressions of the first straight line and the third straight line. According to the principle of projection transformation, the target intersection point coordinates are the actual center position of the out-of-focus image mark.

9. A device for determining the actual center of a defocused concentric circle image in visual metrology, characterized in that, It comprises: A data acquisition module is configured to acquire an out-of-focus image of a concentric circle mark image after perspective projection transformation, and determine inner and outer ellipse center point information of the out-of-focus image. A data processing module is configured to determine expressions of a first straight line, a second straight line and a third straight line based on the inner and outer ellipse center point information. A determination module is configured to calculate target intersection point information of the first straight line and the third straight line, and the target intersection point is the actual center of the out-of-focus image. The first straight line is a straight line passing through the inner and outer ellipse center points, the second straight line is parallel to the first straight line and has a distance of half the length of the inner ellipse short axis from the first straight line, and has two intersection points with the inner and outer ellipses, and the third straight line is a straight line passing through the intersection points of the two tangent lines of the inner ellipse and the intersection points of the two tangent lines of the outer ellipse, the two tangent lines of the inner ellipse are straight lines passing through the two intersection points of the second straight line and the inner ellipse, and the two tangent lines of the outer ellipse are straight lines passing through the two intersection points of the second straight line and the outer ellipse.

10. An electronic device comprising a memory, a processor, and a computer program stored on the memory and executable on the processor, characterized in that, When the processor executes the program, the method for determining the actual center of the out-of-focus concentric circle image in visual measurement according to any one of claims 1 to 8 is realized.

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