Method, system and non-transitory computer readable recording medium for correcting luminance of a spherical image

Abstract

The present application relates to a method, system and non-transitory computer readable recording medium for correcting luminance of a spherical image. According to an aspect of the present application, there is provided a method for correcting luminance of a spherical image, comprising: calculating a photographing luminance distribution of a region corresponding to a sphere as a physical quantity measurement object in a plurality of images photographed with respect to the sphere; and correcting the photographing luminance distribution of the region corresponding to the sphere in at least one of the plurality of images with reference to a reference luminance distribution.

Description

[0001] This application is a divisional application of the invention entitled "Method, System and Non-transitory Computer-readable Recording Medium for Correcting the Brightness of a Spherical Image" filed on June 28, 2017, with the applicant being Clarity Inc. Technical Field

[0002] The present invention relates to a method, system, and non-transitory computer-readable recording medium for correcting the brightness of a spherical image. Background Technology

[0003] Virtual golf systems, which allow golfers to virtually play golf even in city centers at a relatively low cost, are becoming increasingly popular. The basic concept of such systems is that when a golfer hits a golf ball, multiple images of the ball are captured, and based on its trajectory, spacing, size, and other physical parameters, a simulation is performed and displayed on the screen. In these virtual golf systems, it is crucial to capture images of the golf ball in the best possible condition.

[0004] Relatedly, Korean Patent Publication No. 10-2009-0112538 (Invention Title: Golf Image Acquisition Device Utilizing Lighting Control and Golf Practice System Based on Image Processing Utilizing the Same) discloses a technique for capturing golf practice scenes while adjusting the position or color of the lighting, thereby acquiring more diverse images of golf balls (the entire description of the aforementioned Korean Patent Publication should be considered incorporated into this specification). However, many prior art techniques, including this one, do not actually concern themselves with techniques for acquiring golf ball images in good condition for accurate measurement of the physical quantities of a golf ball, or techniques for measuring the physical quantities of a golf ball using a sequence of markers that can be acquired from multiple golf ball images.

[0005] Therefore, the inventors propose a new technology to analyze the mark sequence appearing in golf ball images acquired from a high-speed camera, thereby accurately measuring the physical quantities of the golf ball, wherein the high-speed camera is capable of capturing many frames of images in a short period of time. Summary of the Invention

[0006] Technical problems to be solved

[0007] The purpose of this invention is to analyze the marker sequence appearing in multiple golf ball images and measure the rotation speed and direction of the golf ball.

[0008] Another objective of the present invention is to correct the brightness (specifically, the brightness distribution) of multiple golf ball images, thereby making the brightness distribution of the multiple golf ball images uniform.

[0009] Solution to the technical problem

[0010] The representative structure of the present invention for achieving the stated objective is as follows.

[0011] According to one aspect of the present invention, a method for correcting the brightness of a sphere image is provided, comprising: calculating the shooting brightness distribution of a region corresponding to the sphere in a plurality of images of the sphere being measured as a physical quantity; and correcting the shooting brightness distribution of a region corresponding to the sphere in at least one of the plurality of images, using a reference brightness distribution.

[0012] According to another aspect of the present invention, a system for correcting the brightness of a sphere image is provided, comprising: an image acquisition unit for acquiring a plurality of images of a sphere, which is a physical quantity to be measured; and an image correction unit for calculating the shooting brightness distribution of a region corresponding to the sphere in each of the plurality of images, and correcting the shooting brightness distribution of the region corresponding to the sphere in at least one of the plurality of images with reference to a reference brightness distribution.

[0013] In addition, other methods, systems, and non-transitory computer-readable recording media for implementing the present invention are also provided.

[0014] Invention Effects

[0015] According to the present invention, uniform brightness distribution can be achieved not only within each golf ball image, but also across multiple golf ball images, thereby enabling more accurate detection of marker sequences appearing in multiple golf ball images.

[0016] According to the present invention, by utilizing the temporal set of marks appearing in multiple golf ball images (i.e., mark sequence), the effect of accurately measuring the spin speed and spin direction of the golf ball can be achieved. Attached Figure Description

[0017] Figure 1 This is a schematic diagram illustrating the overall structure of a virtual golf system according to an embodiment of the present invention.

[0018] Figure 2 This is a diagram illustrating in detail the internal structure of a shooting device 100 according to an embodiment of the present invention.

[0019] Figure 3 This is a diagram illustrating in detail the internal structure of a simulator 200 according to an embodiment of the present invention.

[0020] Figure 4 This is a schematic diagram showing an actual image of a golf ball taken according to an embodiment of the present invention.

[0021] Figure 5 This is a diagram visually displaying a correction model applicable to a golf ball image, according to an embodiment of the present invention.

[0022] Figure 6 This is a schematic diagram showing a golf ball image with brightness corrected according to an embodiment of the present invention.

[0023] Explanation of reference numerals in the attached figures

[0024] 100: Filming equipment

[0025] 110: Camera Department

[0026] 120: Ministry of Communications

[0027] 130: Control Department

[0028] 200: Simulator

[0029] 210: Image Processing Department

[0030] 220: Physical Quantity Measurement Department

[0031] 230: Simulation Department

[0032] 240: Database

[0033] 250: Ministry of Communications

[0034] 260: Control Department Detailed Implementation

[0035] The detailed description of the invention described below refers to the accompanying drawings, which illustrate specific embodiments in which the invention may be practiced. These embodiments are described in detail to enable those skilled in the art to fully implement the invention. While the various embodiments of the invention differ from one another, they should be understood to be mutually exclusive. For example, specific shapes, structures, and characteristics described herein can be implemented from one embodiment to another without departing from the spirit and scope of the invention. Furthermore, the position and arrangement of individual structural elements in the various embodiments should also be understood to be subject to change without departing from the spirit and scope of the invention. Therefore, the detailed description described below is not intended to be limiting, and the scope of the invention should be considered to include the scope claimed by the claims and all equivalents thereof. Similar reference numerals in the drawings denote the same or similar structural elements in various respects.

[0036] Hereinafter, in order to enable those skilled in the art to readily implement the present invention, various preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0037] [Preferred Embodiment of the Invention]

[0038] Overall system structure

[0039] Figure 1 This is a schematic diagram illustrating the overall structure of a virtual golf system according to an embodiment of the present invention.

[0040] like Figure 1 As shown, the virtual golf system may include a hitting unit 10, a lighting device 20, a shooting device 100, a simulator 200, and a display device 300.

[0041] First, in one embodiment of the present invention, the striking part 10 can be a part where a golfer can stand on a golf ball and hit it when using a virtual golf system. Such a striking part 10 can include a known sloped return table with an adjustable tilt angle. For reference, when the present invention is applied to other types of virtual sports systems, those skilled in the art can appropriately modify the structure of the striking part 10 according to the characteristics of the corresponding sports, and if necessary, modify the structure of other structural elements linked to it.

[0042] Then, in one embodiment of the invention, the lighting device 20 can be a device that can artificially illuminate the golf ball while the golfer is enjoying virtual golf indoors or outdoors. This lighting device 20 can be turned on or off as needed, or its brightness can be adjusted. Preferably, the lighting device 20 can be infrared illumination to prevent the golf ball image from naturally deteriorating due to light flickering.

[0043] Then, the shooting device 100 of one embodiment of the present invention may include at least one camera (e.g., a high-speed camera) (not shown in the figures) to perform the function of acquiring two or more golf ball images (e.g., images of a golf ball in motion). This shooting device 100 can be as follows: Figure 1 The position shown is that of a golf ball in motion viewed from above, but it can also be positioned in other different locations.

[0044] According to one embodiment of the invention, the more clearly the designated marks on the surface of the golf ball are displayed, the more advantageous it is to specify the shape or position of the marks, and thus, it can be said that the image of the golf ball is better. For example, when the marks marked in the area corresponding to the ball in the golf ball image are clearer, the simulator 200, as described later, can more accurately capture the mark sequence as a set of mark timestamps appearing in multiple golf ball images, and more accurately calculate the spin speed and direction of the golf ball. Furthermore, for example, when the image of the golf ball is clearer, the simulator 200 can more accurately capture the center point or the point of maximum brightness in multiple golf ball images, and more accurately calculate the brightness distribution of the area corresponding to the golf ball.

[0045] Regarding the specific structure of the shooting device 100 as described above, it will be referred to below. Figure 2 Further explanation is needed.

[0046] Then, the simulator 200 of one embodiment of the present invention can perform the following functions: acquiring multiple images of a ball (as the object of physical quantity measurement) captured by the imaging device 100; calculating the shooting brightness distribution of the region corresponding to the ball in each of the multiple images; and correcting the shooting brightness distribution of the region corresponding to the ball in at least one of the multiple images using a reference brightness distribution, thereby making the brightness distribution of the multiple golf ball images more uniform. Furthermore, the simulator 200 of one embodiment of the present invention can also perform the following functions: analyzing the set of temporal sequences of marks appearing in the multiple golf ball images corrected as described above (i.e., mark sequences) to measure the rotation speed and direction of rotation of the golf ball. Additionally, the simulator 200 of one embodiment of the present invention can realize the movement of the golf ball in virtual reality based on the relevant information of the rotation speed and direction of rotation of the golf ball measured as described above.

[0047] On the other hand, the simulator 200 of one embodiment of the present invention can communicate with the shooting device 100 and the display device 300, and may include a dedicated processor for virtual golf simulation. This dedicated processor may have a storage device and possess numerical computation and graphics processing capabilities.

[0048] Regarding the structure of simulator 200 as described above, please refer to the following... Figure 3 Further explanation is needed.

[0049] Finally, the display device 300 of one embodiment of the present invention can perform the functions of displaying the physical quantity measurement and virtual reality realization results of the display simulator 200. This display device 300 can display specified images using a specified display device, for example, it can consist of a screen that absorbs the impact of a struck golf ball and does not directly emit light, and a projector that outputs images onto such a screen.

[0050] Structure of the filming device

[0051] The internal structure of the imaging device 100 according to an embodiment of the present invention and the function of each structural element are described below.

[0052] Figure 2 This is a diagram illustrating in detail the internal structure of a shooting device 100 according to an embodiment of the present invention.

[0053] like Figure 2 As shown, the shooting device 100 may include a camera unit 110, a communication unit 120, and a control unit 130.

[0054] According to one embodiment of the present invention, the camera unit 110, the communication unit 120, and the control unit 130 may be program modules, at least some of which communicate with the simulator 200. Such program modules may be included in the shooting device 100 in the form of an operating system, application module, or other program modules, and physically, may be stored in various known storage devices. Alternatively, such program modules may be stored in a remote storage device capable of communicating with the shooting device 100. On the other hand, such program modules include, but are not limited to, routines, subroutines, programs, objects, components, data structures, etc., that perform specific tasks or run specific abstract data types according to the present invention.

[0055] First, the camera unit 110 of one embodiment of the present invention may include a camera capable of acquiring multiple images optically. For example, the camera unit 110 of one embodiment of the present invention may include a high-speed camera or an ultra-high-speed camera capable of capturing images at tens of frames per second. According to one embodiment of the present invention, the camera of the camera unit 110 can perform shooting in a state where a moving golf ball is present or in a state where a moving golf ball is not present, and acquire a predetermined image.

[0056] Then, the communication unit 120 of one embodiment of the present invention can perform the mediating function of sending and receiving data between the control unit 130 and the simulator 200 as needed. According to one embodiment of the present invention, there are no particular limitations on the communication method that the communication unit 120 can adopt, but it is preferred to use wired communication methods such as wired LAN communication or cable communication, or wireless communication methods such as wireless LAN communication, infrared communication, RF communication, Bluetooth communication, etc.

[0057] Finally, the control unit 130 of one embodiment of the present invention can perform the function of controlling the data flow between the camera unit 110 and the communication unit 120. That is, the control unit 130 of the present invention controls the data flow from the shooting device 100 to the outside / from the outside to the shooting device 100 or controls the data flow between the various structural elements of the shooting device 100, thereby enabling the camera unit 110 and the communication unit 120 to perform their respective inherent functions.

[0058] Simulator Structure

[0059] The internal structure of a simulator 200 according to an embodiment of the present invention and the functions of each structural element are described below.

[0060] Figure 3 This is a diagram illustrating in detail the internal structure of a simulator 200 according to an embodiment of the present invention.

[0061] like Figure 3 As shown, the simulator 200 of one embodiment of the present invention may be configured as an image processing unit 210, a physical quantity measurement unit 220, an analog unit 230, a database 240, a communication unit 250, and a control unit 260. Furthermore, according to one embodiment of the present invention, the image processing unit 210 may include an image acquisition unit (not shown) and an image correction unit (not shown). According to one embodiment of the present invention, at least some of the image processing unit 210, physical quantity measurement unit 220, analog unit 230, database 240, communication unit 250, and control unit 260 may be program modules that communicate with the imaging device 100 or the display device 300. Such program modules may be included in the simulator 200 in the form of an operating system, application module, or other program modules, and physically, may be stored in various known storage devices. Alternatively, such program modules may also be stored in a remote storage device capable of communicating with the simulator 200. On the other hand, such program modules include, but are not limited to, routines, subroutines, programs, objects, components, data structures, etc., that perform specific tasks or run specific abstract data types according to the present invention.

[0062] On the other hand, although the simulator 200 has been described as described above, such description is merely exemplary, and some or all of the functional or structural elements required by the simulator 200 may also be implemented or included in the shooting device 100 as needed, which is self-evident to those skilled in the art.

[0063] First, according to one embodiment of the present invention, the image processing unit 210 (specifically, the image acquisition unit) can perform the function of acquiring multiple images of a ball that is a physical quantity measurement object from the above-mentioned imaging device 100.

[0064] Figure 4 This is a schematic diagram showing an actual image of a golf ball taken according to an embodiment of the present invention.

[0065] Reference Figure 4 Due to various environmental factors such as the location of the lighting, the direction or intensity of the light, the location, specifications or settings of the camera, and the position or color of the ball, the brightness distribution of the area corresponding to the ball will vary from image to image. For example, the brightness of the area corresponding to the ball may be generally darker (see reference). Figure 4 (a)) The brightness of the central part of the area corresponding to the sphere may be too bright compared to other parts (see reference). Figure 4 (b)

[0066] First, according to one embodiment of the present invention, the image processing unit 210 (specifically, the image correction unit) can perform the function of calculating the shooting brightness distribution of the corresponding area of ​​the ball from multiple images of the ball, which is the object of physical quantity measurement.

[0067] Specifically, an image correction unit of one embodiment of the present invention can calculate the center location, maximum brightness location, radius, etc. of the region corresponding to the sphere from multiple images, thereby enabling specific correction of the region corresponding to the sphere within each image. Furthermore, an image correction unit of one embodiment of the present invention can calculate the brightness distribution of the region corresponding to the sphere in multiple images, based on predetermined locations (e.g., center location, maximum brightness location, etc.) within the region corresponding to the sphere.

[0068] More specifically, the image correction unit of one embodiment of the present invention can use estimation models such as linear regression models or non-parametric models or statistical models to calculate the brightness distribution of the region corresponding to the sphere in multiple images.

[0069] For example, based on a linear regression model, the relationship between the location of maximum brightness and the distance between any two locations and the brightness of that arbitrary location can be derived within the region corresponding to the sphere in multiple images. As another example, the brightness of any location within the region corresponding to the sphere can be calculated in multiple images using non-parametric models such as blurring filters, low-pass filters, and Gaussian filters.

[0070] Furthermore, according to one embodiment of the present invention, the image processing unit 210 (specifically, the image correction unit) can perform the following function: correcting the captured brightness distribution of at least one image of a plurality of images corresponding to the sphere, with reference to a reference brightness distribution. Wherein, according to one embodiment of the present invention, the reference brightness distribution is a brightness distribution pre-set to be suitable for detecting and identifying marks marked on the surface of the sphere, and can be stored in the database 240.

[0071] Specifically, in one embodiment of the present invention, the image correction unit can correct the shooting brightness distribution of the area corresponding to the sphere in the image by such that the uniformity of the shooting brightness distribution of the area corresponding to the sphere in the image being corrected reaches a preset level or higher.

[0072] More specifically, in one embodiment of the present invention, the image correction unit compares the first captured brightness distribution of the region corresponding to the sphere in the first image with a reference brightness distribution, thereby calculating a correction model for correcting the first captured brightness distribution, and correcting the first captured brightness distribution with reference to the correction model calculated above.

[0073] For example, the correction model of one embodiment of the present invention can be represented as shown in the following mathematical formulas 1 and 2.

[0074] <Mathematical Formula 1>

[0075] E(P)=c*B(P)+d

[0076] <Mathematical Formula 2>

[0077] F(P) = B(P) + E(P) or F(P) = B(P) * E(P)

[0078] In the above mathematical formulas 1 and 2, B(P) represents the brightness of point P at any location, E(P) represents the correction model for the brightness of point P, c and d represent specific correction coefficients applied to the correction model E(P), and F(P) represents the brightness of point P corrected (i.e., homogenized) according to the correction model E(P).

[0079] Figure 5 This is a diagram visually displaying a correction model applicable to a golf ball image, according to an embodiment of the present invention. Figure 5 (a) and (b) are respectively applicable to Figure 4 The corresponding situation is to visualize the correction model of images (a) and (b).

[0080] Figure 6 This is a schematic diagram showing a golf ball image with brightness corrected according to an embodiment of the present invention.

[0081] Reference Figure 6 It can be confirmed that, Figure 4 The brightness distribution of the corresponding area of ​​the golf ball in the golf ball images shown in (a) and (b) is made uniform.

[0082] As explained above, according to one embodiment of the present invention, the brightness distribution of the area corresponding to the ball is corrected (i.e., homogenized) not only within each golf ball image but also in multiple golf ball images, thereby reducing the possibility of errors due to brightness differences in detecting and recognizing marks that appear in multiple images, and improving the accuracy of detection and recognition.

[0083] However, according to the present invention, the method for correcting the brightness distribution of a golf ball image is not necessarily limited to the algorithms listed above, and can be arbitrarily modified within the scope of achieving the purpose of the present invention.

[0084] On the other hand, the physical quantity measurement unit 220 of one embodiment of the present invention can perform the following function: analyze the marker sequence appearing in multiple golf ball images (more specifically, multiple golf ball images that are temporally adjacent) that have been corrected as described above (i.e., brightness distribution uniformization), thereby measuring the rotation speed and rotation direction of the golf ball. Specifically, the physical quantity measurement unit 220 of one embodiment of the present invention can estimate the rotation speed and rotation direction of the golf ball by using the movement speed and movement direction of the markers on the surface of the golf ball observed from the above marker sequence as a reference. In addition, the physical quantity measurement unit 220 of one embodiment of the present invention can also perform functions such as calculating the trajectory of the golf ball, calculating the speed of the golf ball, or calculating the height of the golf ball.

[0085] Then, the simulation unit 230 of one embodiment of the present invention can realize the movement of the golf ball (e.g., rotation speed, rotation direction, movement speed, movement direction, launch angle, etc.) in virtual reality based on various information related to the physical quantities of the golf ball measured as described above. In addition, the simulation unit 230 of one embodiment of the present invention can reflect the movement of the golf ball on a graphic object, or transmit control signals including image signals to the display device 300, so as to realistically represent the movement of the golf ball in the display device 300.

[0086] Then, in the database 240 of one embodiment of the present invention, information such as images of golf balls, images with corrected brightness distribution of golf balls, marker sequences, and calculated physical quantities, or information required for simulation (e.g., data required to realize virtual reality), can be stored. Although in Figure 3The illustration shows a configuration where database 240 is included within simulator 200. However, depending on the needs of those skilled in the art implementing this invention, database 240 may also be configured independently of simulator 200. Furthermore, the concept of database 240 in this invention, encompassing computer-readable recording media, is not limited to a database in the narrow sense; it can also be a database in a broader sense, including data records based on a file system. Even a simple set of logarithms, if data can be retrieved and extracted from it, can also constitute database 240 in this invention.

[0087] Then, the communication unit 250 of one embodiment of the present invention can perform the function of sending and receiving data to / from the simulator 200. According to one embodiment of the present invention, there are no particular limitations on the communication method that the communication unit 250 can adopt, but it is preferred to use wired communication methods such as wired LAN communication or cable communication, or wireless communication methods such as wireless LAN communication, infrared communication, RF communication, Bluetooth communication, etc.

[0088] Finally, in one embodiment of the present invention, the control unit 260 can perform the function of controlling the data flow between the image processing unit 210, the physical quantity measurement unit 220, the simulation unit 230, the database 240, and the communication unit 250. That is, the control unit 260 of the present invention controls the data flow from the simulator 200 to the outside / from the outside to the simulator 200, or the data flow between the various structural elements of the simulator 200, thereby enabling the image processing unit 210, the physical quantity measurement unit 220, the simulation unit 230, the database 240, and the communication unit 250 to perform their respective inherent functions.

[0089] The above description primarily assumes that the virtual sports system of the present invention is a virtual golf system. However, the technical principles and structure of the present invention can be applied to all kinds of virtual sports systems (e.g., virtual baseball systems or virtual soccer systems) that require simulation of the movement of a ball, which is self-evident to those skilled in the art.

[0090] The embodiments of the present invention described above can be implemented in the form of program commands that can be executed through various computer architecture elements and recorded on a computer-readable recording medium. The computer-readable recording medium may include program commands, data files, data structures, etc., individually or in combination. The program commands recorded on the computer-readable recording medium may be specifically designed and configured for the present invention, or may be known and usable by those skilled in the art of computer software. Examples of computer-readable recording media include magnetic media such as hard disks, floppy disks, and magnetic tapes; optical recording media such as CD-ROMs and DVDs; magneto-optical media such as floppy disks; and hardware devices specifically configured to store and execute program commands, such as ROMs, RAMs, and flash memory. Examples of program commands include not only machine language code formed by a compiler, but also high-level language code that can be executed by a computer using an interpreter or the like. The hardware device may be modified to perform the processing required for the present invention by replacing one or more software modules, or vice versa.

[0091] The present invention has been described above with reference to specific details and limited embodiments, such as specific structural elements, and the accompanying drawings. However, this is only provided to help to understand the present invention more fully, and the present invention is not limited to the described embodiments. Any modifications and changes can be derived from this description by those skilled in the art.

[0092] Therefore, the concept of the present invention is not limited to the embodiments described herein, nor is it limited to the claims described below. All scopes equivalent to or modified therefrom of the claims are within the scope of the concept of the present invention.

Claims

1. A method for correcting the brightness of a spherical image, comprising: The step of calculating the image brightness distribution of the region corresponding to the sphere in each of a plurality of images taken of the sphere, which is the object of physical quantity measurement; as well as Using a reference brightness distribution as a reference, the brightness distribution of the region corresponding to the ball in each of the plurality of images is corrected so that the uniformity of the brightness distribution of the region corresponding to the ball in the plurality of images reaches a preset level or above. The reference brightness distribution is a brightness distribution that is preset to be suitable for detecting and recognizing the markings on the surface of the ball. In the correction step, for any point in the region corresponding to the sphere in each of the plurality of images, a correction model is calculated to correct the brightness of the arbitrary point.

2. The method according to claim 1, wherein, In the calculation steps, The shooting brightness distribution is calculated using at least one of a linear regression model and a nonparametric model.

3. The method according to claim 1, wherein, In the calculation steps, In the plurality of images, the shooting brightness distribution is calculated using at least one of the center coordinates and the maximum brightness coordinates of the region corresponding to the sphere as a reference.

4. The method according to claim 1, wherein, The correction steps include: The steps of comparing the first image's brightness distribution in the region corresponding to the sphere with the reference brightness distribution to calculate a correction model for correcting the first image's brightness distribution; and The step of correcting the brightness distribution of the first image using the calculated correction model as a reference.

5. The method according to claim 4, wherein, The correction model is specific based on at least one correction coefficient.

6. A computer-readable recording medium having a computer program recorded thereon for performing the method of claim 1.

7. A system for correcting the brightness of a spherical image, comprising: The image acquisition unit acquires multiple images of the sphere, which is the object of physical quantity measurement. as well as The image correction unit calculates the shooting brightness distribution of the region corresponding to the ball in each of the plurality of images, and corrects the shooting brightness distribution of the region corresponding to the ball in each of the plurality of images with reference to a reference, so that the uniformity of the shooting brightness distribution of the region corresponding to the ball in the plurality of images reaches a preset level or above, wherein the reference brightness distribution is a brightness distribution preset to be suitable for detecting and recognizing the markings on the surface of the ball; The image correction unit calculates a correction model for correcting the brightness of any point in the region corresponding to the sphere in each image.

8. The system according to claim 7, wherein, The image correction unit calculates the captured brightness distribution using at least one of a linear regression model and a non-parametric model.

9. The system according to claim 7, wherein, The image correction unit calculates the captured brightness distribution in the plurality of images, using at least one of the center coordinates and maximum brightness coordinates of the region corresponding to the sphere as a reference.

10. The system according to claim 7, wherein, The image correction unit compares the first shooting brightness distribution of the region corresponding to the sphere in the first image with the reference brightness distribution, thereby calculating a correction model for correcting the first shooting brightness distribution, and using the calculated correction model as a reference, corrects the first shooting brightness distribution.

11. The system according to claim 10, wherein, The correction model is specific based on at least one correction coefficient.

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