Method for eliminating distortion in array ct images

Abstract

The present application belongs to the field of micro-CT imaging technology, and particularly relates to a method for eliminating array CT image distortion, which can compensate for gray scale and correct distortion in view of the defects of current CT imaging. The method for eliminating array CT image distortion is applied to an array CT imaging system, and the method for eliminating array CT image distortion comprises the following steps: acquiring a gray scale compensation reference formula of the array CT imaging system; acquiring a calibration plate image, compensating for the gray scale of the calibration plate image, and acquiring a distortion elimination characteristic formula of the array CT imaging system; forming an image of a to-be-imaged object according to the array CT imaging system, and correcting the distortion of the image of the to-be-imaged object according to the distortion elimination characteristic formula; and forming an image of a to-be-imaged object according to the array CT imaging system, and correcting the distortion of the image of the to-be-imaged object according to the distortion elimination characteristic formula.

Description

Technical Field

[0001] This invention belongs to the field of micro-CT imaging technology, and particularly relates to a method for eliminating distortion in array CT images. Background Technology

[0002] Micro-CT is a detection method that acquires information about the internal structure of a sample without damaging it. Due to its high resolution, micro-CT has important applications in industrial engineering, medical care, and education. Optical couplers, as crucial components in micro-CT systems for X-ray imaging, offer advantages such as high sensitivity, resistance to strong light, and vibration resistance. Optical coupler systems mainly consist of optical components and high-resolution CCDs. During imaging, geometric distortion inevitably occurs, leading to image distortion and reduced image quality. After geometric distortion, the sample exhibits linear, radial, and tangential distortion. Generally, tangential distortion is difficult to occur during camera imaging, provided the manufacturing process is maintained; therefore, most camera distortion problems primarily involve linear and radial distortion.

[0003] To address the aforementioned distortion issues, there are currently two main solutions in the field of visible light cameras: grid distortion correction and polynomial distortion correction. Grid distortion correction primarily involves imaging a standard grid using the imaging system, then registering the actual image with an ideal grid. Regions are divided using control points within the grid, and calibration is performed on the actual and ideal control points for each region. Finally, the overall image is corrected through grid transformation. However, when using grid distortion correction for micro-CT system calibration, the method struggles to effectively correct image distortion due to the often concentrated grayscale distribution. Polynomial distortion correction, on the other hand, requires the use of a calibration plate for imaging. Special points or features on the calibration plate are marked, and the coordinates of ideal points are determined based on the fixed geometric relationships between these points or features. Polynomial simulation is then performed on the actual and ideal feature sets to obtain the distortion parameters for the entire image. These parameters are then used to derive and ultimately correct the overall image distortion.

[0004] Micro-CT uses an X-ray source for imaging. Since the X-ray source is a point light source, the brightness of the center point of the image (the orthographic projection position of the X-ray source) is high and the surrounding area is dark. In other words, after micro-CT images the object to be imaged, there is a situation where the gray level of the image is low around the edges. During the distortion correction process, the equipment may not be able to identify special points or features of the pattern on the calibration board, resulting in the inability to accurately perform distortion correction. Summary of the Invention

[0005] To overcome the shortcomings of the aforementioned related technologies, the present invention provides a method for eliminating distortion in array CT images, which can perform grayscale compensation and distortion correction for the defects of current CT imaging.

[0006] To achieve the above objectives, the present invention provides a method for eliminating distortion in array CT images. The method is applied to an array CT imaging system and includes: obtaining a grayscale compensation reference formula for the array CT imaging system; acquiring a calibration plate image, performing grayscale compensation on the calibration plate image, and obtaining a distortion elimination feature formula for the array CT imaging system; forming an image of the object to be imaged according to the array CT imaging system, and correcting the distortion of the image according to the distortion elimination feature formula.

[0007] Preferably, the array CT imaging system includes an X-ray source, a clamping device, and an imaging unit, wherein the X-ray source, clamping device, and imaging unit are arranged sequentially on the same straight line. The method for obtaining the grayscale compensation reference formula of the array CT imaging system includes: object-free imaging and standard metal plate imaging. Object-free imaging includes zero objects clamped on the clamping device, the X-ray source irradiating the imaging unit to form a first image, establishing a first image coordinate system on the first image, with the origin of the first image coordinate system coinciding with the center point of the first image, and obtaining the grayscale compensation three-dimensional surface formula of the first image. Standard metal plate imaging includes a standard metal plate clamped on the clamping device, the X-ray source irradiating the standard metal plate to form a second image, establishing a second image coordinate system on the second image, with the origin of the second image coordinate system coinciding with the center point of the second image, and obtaining the grayscale compensation three-dimensional surface formula of the second image.

[0008] Preferably, the method for obtaining the distortion correction feature formula of the array CT imaging system includes: a standard calibration plate is provided on the clamping member, and the array CT imaging system forms a third image with respect to the standard calibration plate. A third image coordinate system is established on the third gray-scale compensated image, and gray-scale compensation is performed on the third image according to the gray-scale compensation reference formula to form a third gray-scale compensated image. Image coordinate points of multiple features are obtained on the third gray-scale compensated image. A world coordinate system is established on the image formed by the orthographic projection of the standard calibration plate onto the plane where the third image is located, and world coordinate points corresponding to the image coordinate points of the multiple features in the world coordinate system are obtained. The distortion correction feature formula is obtained based on the image coordinate points and the corresponding world coordinate points.

[0009] Preferably, the method for obtaining the distortion elimination feature formula based on the plurality of image coordinate points and the corresponding world coordinate points includes: using a particle swarm optimization algorithm to fit the plurality of image coordinate points and the corresponding world coordinate points to obtain the distortion elimination feature formula.

[0010] Preferably, before performing distortion correction on the image of the object to be imaged according to the distortion elimination feature formula, gray-level compensation is performed on the image of the object to be imaged according to the gray-level compensation reference formula to form a gray-level compensated image to be imaged. Distortion correction is then performed on the gray-level compensated image to be imaged according to the distortion elimination feature formula.

[0011] The beneficial effects of this invention are as follows:

[0012] Obtaining a grayscale compensation reference formula allows for grayscale compensation of the image to be imaged, ensuring consistent grayscale levels for objects with the same thickness, facilitating subsequent distortion correction. Furthermore, grayscale compensation in the surrounding areas of the image makes it easier for the device to identify specific points or features, improving the accuracy of distortion correction. Attached Figure Description

[0013] To more clearly illustrate the technical solutions in the embodiments of the present invention or related technologies, the drawings used in the description of the embodiments or related technologies will be briefly introduced below. Obviously, the 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.

[0014] Figure 1 A structural diagram of an array CT imaging system provided by the present invention;

[0015] Figure 2 A structural diagram of the X-ray source provided by the present invention;

[0016] Figure 3 The method for eliminating array CT image distortion provided by the present invention is illustrated in the following step diagrams;

[0017] Figure 4 This invention provides a step diagram illustrating the method for obtaining the grayscale compensation reference formula for the array CT imaging system.

[0018] Figure 5 A first image provided for this invention;

[0019] Figure 6 A schematic diagram of the first image and the established first image coordinate system provided for this invention;

[0020] Figure 7 A step diagram illustrating the method for obtaining the distortion elimination feature formula of the array CT imaging system provided by the present invention;

[0021] Figure 8 A third image provided by the present invention;

[0022] Figure 9 A schematic diagram of the third image and the established coordinate system of the third image provided by the present invention;

[0023] Figure 10 A schematic diagram of the standard calibration plate and the established world coordinate system provided for this invention. Detailed Implementation

[0024] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, 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 some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0026] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation", "connection", and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection. The term "connection" can refer to a direct connection, an indirect connection through an intermediate medium, or a connection between the internal components of two elements. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] In some embodiments, such as Figure 1 As shown, the array CT imaging system may include an X-ray source 1, a clamping device 2, and an imaging unit 3, wherein the X-ray source 1, the clamping device 2, and the imaging unit 3 are arranged sequentially on the same straight line.

[0028] In some examples, the X-ray source 1 of industrial equipment typically uses an X-ray tube. Its principle is to use a high-voltage electric field to bombard the anode target with high-speed electrons, causing electron transitions and emitting primary X-rays. These primary X-rays are then used to irradiate the sample, causing electron transitions and emitting secondary X-rays. It can be understood that X-ray source 1 is generally a point source; that is, when X-ray source 1 irradiates in one direction, the X-rays are cone-shaped, for example... Figure 2 As shown.

[0029] The clamping component 2 is used to clamp the object being imaged, such as the object to be imaged or other metal parts used for testing.

[0030] The imaging unit 3 is used to receive X-rays passing through the clamped member 2 to form an image of the object being imaged, which is mounted on the clamped member.

[0031] Because the imaging principle of imaging unit 3 is closely related to the intensity of the received X-rays, for example, when passing through a thicker area of ​​the object being imaged, the X-ray attenuation intensity is greater, the X-rays received by imaging unit 3 are weaker, and the grayscale of the image of the thicker area by imaging unit 3 is lower; correspondingly, when passing through a thinner area of ​​the object being imaged, the X-ray attenuation intensity is smaller, the X-rays received by imaging unit 3 are stronger, and the grayscale of the image of the thinner area by imaging unit 3 is higher.

[0032] X-rays irradiate the object being imaged in a conical shape. Taking an object of uniform thickness as an example, with its center collinear with the centerline of the conical structure, we can see that the X-ray intensity near the centerline is greater than that at the edges. Furthermore, the distance X-rays travel through the centerline to reach the object is less than the distance they travel through the edges. The longer the distance X-rays travel in air, the greater their attenuation. In summary, the intensity of X-rays near the centerline is greater than that near the edges. Therefore, the central region of the image has a higher grayscale value, while the edge region has a lower grayscale value.

[0033] In some embodiments, the imaging unit 3 suffers from linear and radial distortion during the imaging process. Generally, the distortion amplitude is larger in the edge regions of the image, while the gray level of the edge regions is lower. Therefore, during the distortion correction process, the device may fail to correct distortion in the edge regions of the image that are too dark because the device cannot accurately identify special points or features.

[0034] Based on this, some embodiments of the present invention provide a method for eliminating array CT image distortion. The method for eliminating array CT image distortion is applied to an array CT imaging system, wherein, as... Figure 3 As shown, the method for eliminating array CT image distortion includes steps S1 to S3.

[0035] S1. Obtain the grayscale compensation reference formula of the array CT imaging system.

[0036] S2. Obtain the calibration plate image, perform grayscale compensation on the calibration plate image, and obtain the distortion elimination feature formula of the array CT imaging system.

[0037] S3. The array CT imaging system forms an image of the object to be imaged, and the distortion correction is performed on the image of the object to be imaged according to the distortion elimination feature formula.

[0038] In some examples, a grayscale compensation reference formula for the array CT imaging system is obtained. During the process of obtaining the distortion correction feature formula, the array CT imaging system needs to image a calibration plate. Because the X-ray source is a point source, the calibration plate image has a high grayscale value in the center and a low grayscale value at the periphery. To improve the equipment's recognition of peripheral features, the aforementioned grayscale compensation reference formula is used to perform grayscale compensation on the calibration plate image. This facilitates improving the grayscale of the calibration plate image's periphery, resulting in higher feature resolution around the calibration plate image, making it easier for the equipment to recognize and obtain an accurate distortion correction feature formula.

[0039] An array CT imaging system generates an image of the object to be imaged, and distortion correction of the image can be achieved by combining the distortion elimination feature formula.

[0040] The distortion elimination feature formula obtained after grayscale compensation of the calibration plate image has high accuracy. Therefore, the distortion correction result of the image of the object to be imaged is relatively accurate, which is beneficial to the array CT imaging system to improve the imaging quality of the object to be imaged.

[0041] It should be noted that the imaging of the calibration plate is performed by the array CT imaging system on a standard calibration plate. The standard calibration plate can be a metal plate containing multiple through-holes arranged in an array. Each through-hole can be considered a feature on the standard plate image; for example, a feature on a standard plate image is a high-gray-level dot (gray-level relative to the entire standard plate image). Finding the position of each through-hole and its corresponding feature on the standard plate image is convenient, allowing for quick and accurate location of coordinate points, which facilitates the acquisition of distortion correction feature formulas.

[0042] In some embodiments, such as Figure 4 As shown, the method for obtaining the grayscale compensation reference formula of the array CT imaging system includes steps S11 and S12.

[0043] Among them, S11 is objectless imaging;

[0044] The objectless imaging includes: the number of objects clamped on the clamping member is zero; the X-ray source irradiates the imaging unit to form a first image; a first image coordinate system is established on the first image, and the origin of the first image coordinate system coincides with the center point of the first image; and the gray-scale compensation three-dimensional surface formula of the first image is obtained.

[0045] S12 is for standard metal plate imaging;

[0046] The standard metal plate imaging includes: the object held on the clamping member is a standard metal plate; the X-ray source irradiates the standard metal plate to form a second image; a second image coordinate system is established on the second image, and the origin of the second image coordinate system coincides with the center point of the second image; and the gray-scale compensation three-dimensional surface formula of the second image is obtained.

[0047] In some examples, the array CT imaging system performs objectless imaging, meaning that when there are no objects on the clamp, the X-ray source directly irradiates the imaging unit to form an image. As can be seen from the above embodiments, the X-ray source is a point source, and the X-rays are conical. The first image formed by objectless imaging is as follows: Figure 5 As shown, at the center of the first image 4, where the center line of the cone-shaped structure formed by X-rays passes, the energy density of X-rays is higher and the attenuation of X-rays is lowest. Therefore, the gray level at the center of the first image 4 is higher. At the periphery of the first image 4, because X-rays are obliquely irradiated onto the plane where the first image 4 is located, the energy density of X-rays is lower and the attenuation of X-rays is greatest. Therefore, the gray level at the periphery of the first image 4 is lower.

[0048] It is understandable that the distance between the periphery of the first image 4 and the X-ray source and the distance between the center of the first image 4 and the X-ray source are the same. In order to make the distance represented by the gray level of the center of the first image 4 the same as the distance represented by the gray level of the periphery of the first image 4, the gray level of the periphery of the first image 4 can be compensated to be the same as the gray level of the center of the first image 4.

[0049] Using the grayscale value at the center of the first image 4 as a reference, the grayscale values ​​around the periphery of the first image 4 are compensated. Specifically, for example... Figure 6As shown, a first image coordinate system xyz can be established on the first image 4. For example, the origin of the first image coordinate system xyz coincides with the center of the first image 4. The first image coordinate system xyz includes a first coordinate x, a second coordinate y, and a third coordinate z. The first coordinate x, the second coordinate y, and the third coordinate z are mutually perpendicular, and the plane containing the first coordinate x and the second coordinate y overlaps with the first image 4. The first coordinate x and the second coordinate y can represent the coordinate positions on the first image 4, and the third coordinate z can represent the grayscale value that needs to be compensated for the corresponding coordinate position on the first image 4. Thus, the first coordinate x, the second coordinate y, and the third coordinate z form a grayscale compensation three-dimensional surface of the first image 4. The grayscale compensation three-dimensional surface is an elliptical surface, and a formula for the grayscale compensation three-dimensional surface of the first image 4 is established based on the values ​​of multiple coordinate points of the grayscale compensation three-dimensional surface.

[0050] In some examples, the standard metal plate can be the same in thickness and material as the standard calibration plate. The standard metal plate is imaged to form a second image. The gray-scale compensation three-dimensional surface formula of the second image is generated by establishing the gray-scale compensation three-dimensional surface formula of the first image in the manner described in the example above.

[0051] In some embodiments, such as Figure 7 As shown, the method for obtaining the distortion elimination feature formula of the array CT imaging system includes steps S21 to S25:

[0052] S21. A standard calibration plate is provided on the clamping member, and the array CT imaging system forms a third image on the standard calibration plate.

[0053] S22. Establish a third image coordinate system on the third gray-scale compensated image, and perform gray-scale compensation on the third image according to the gray-scale compensation reference formula to form a third gray-scale compensated image.

[0054] S23. Obtain the image coordinates of multiple features on the third grayscale compensated image.

[0055] S24. The standard calibration plate establishes a world coordinate system on the image formed by the orthographic projection of the third image onto the plane, and obtains the world coordinate points of the image coordinate points of the multiple features corresponding to the positions in the world coordinate system.

[0056] S25. Obtain the distortion elimination feature formula based on the image coordinate points and the corresponding world coordinate points.

[0057] In some examples, such as Figure 8 As shown, the standard calibration plate is imaged to form the third image 5. The standard calibration plate can be a metal plate with multiple through holes arranged in an array. The material and thickness of the standard calibration plate are the same as those of the standard metal plate.

[0058] The grayscale of the third image can be compensated using the grayscale compensation three-dimensional surface formulas for the first and second images. Specifically, for example... Figure 9 As shown, a third image coordinate system abc is established on the third image 5, where the origin of the third image coordinate system abc coincides with the center point of the third image 5. The third image coordinate system abc includes a fourth coordinate a, a fifth coordinate b, and a sixth coordinate c. The fourth coordinate a and the fifth coordinate b are located on the third image 5, and can represent the positions of various points in the third image 5. It can be seen that the third image 5 includes an image of a metal plate and multiple features. For example, the coordinate positions of the metal plate image on the third image 5 at the fourth coordinate a and the fifth coordinate b have the same grayscale compensation as the corresponding positions of the second image in the second image coordinate system; similarly, the coordinate positions of the features on the third image 5 at the fourth coordinate a and the fifth coordinate b have the same grayscale compensation as the corresponding positions of the first image in the first image coordinate system. This allows for the grayscale compensation of the third image 5 to form a third grayscale compensated image.

[0059] The features of the third grayscale compensated image are clearly distinguishable from those of the metal plate image, making it easy for the device to identify the features. The device can accurately find the features on the third image and the coordinates of the features on the third image.

[0060] The standard calibration plate establishes a world coordinate system on the image formed by the orthographic projection of the third image onto the plane where the third image is located. That is, as... Figure 10 As shown, a world coordinate system nmo is established on the side of the standard calibration plate 6 facing the imaging unit. For ease of calculation, the origin of the world coordinate system nmo can be aligned with the center of the side of the standard calibration plate 6 facing the imaging unit. The coordinates of each through hole on the standard calibration plate 6 in the world coordinate system nmo are obtained. The distortion elimination feature formula is calculated based on the coordinates of the feature in the third image and the position of the corresponding through hole in the standard calibration plate 6.

[0061] In some embodiments, a distortion correction curve formula can be established, such as the following distortion correction curve formula:

[0062]

[0063]

[0064] Where x represents the value of the feature corresponding to a certain through hole in the fourth coordinate a of the third image coordinate system, y represents the value of the feature corresponding to a certain through hole in the fifth coordinate b of the third image coordinate system, u represents the value of the feature corresponding to the through hole in the fourth coordinate a of the third image coordinate system after distortion correction, and v represents the value of the feature corresponding to the through hole in the fifth coordinate b of the third image coordinate system after distortion correction.

[0065] Here, a0 to a9 and b0 to b9 are parameters. By obtaining the values ​​of x and y, and the corresponding values ​​of u and v, the calculations of a0 to a9 and b0 to b9 can be performed. The parameters are finally confirmed through nonlinear regression, thus establishing the formula for the distortion elimination curve.

[0066] In other embodiments, the method for obtaining the distortion elimination feature formula based on the plurality of image coordinate points and the corresponding world coordinate points includes: using a particle swarm optimization algorithm to fit the plurality of image coordinate points and the corresponding world coordinate points to obtain the distortion elimination feature formula.

[0067] For example, the values ​​of the features corresponding to multiple through holes in the fourth coordinate a and the values ​​of the features corresponding to multiple through holes in the fifth coordinate b of the third image coordinate system are obtained, as well as the distortion-corrected values ​​of the corresponding features in the fourth coordinate a and the fifth coordinate b of the third image coordinate system. The distortion elimination feature formula is then obtained through the particle swarm optimization algorithm.

[0068] Among them, the calculation of polynomial optimization based on particle swarm optimization is an existing technology. Those skilled in the art can obtain the distortion elimination feature formula through the values ​​in the above examples, and detailed parameters are not provided here.

[0069] In some embodiments, before performing distortion correction on the image to be imaged according to the distortion elimination feature formula, gray-level compensation is performed on the image to be imaged according to the gray-level compensation reference formula to form a gray-level compensated image to be imaged. Distortion correction is then performed on the gray-level compensated image to be imaged according to the distortion elimination feature formula.

[0070] For example, during the process of forming a third image from multiple standard calibration plates and calculating the distortion elimination feature formula, the gray-level compensation values ​​corresponding to different gray levels at different positions in the third image coordinate system can be obtained. For example, if the coordinates in the third image coordinate system are (a1, b1) and the gray level of the (a1, b1) coordinate is 100 (the gray level can be 0~255), the gray-level compensation value corresponding to the gray level of the (a1, b1) coordinate can be known. For example, the gray level after compensation for the (a1, b1) coordinate can be 110.

[0071] By performing grayscale compensation on the entire image of the object to be imaged, the accuracy and resolution of the image can be improved.

[0072] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0073] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for eliminating distortion of array CT images, applied to an array CT imaging system, characterized in that, The method for eliminating the distortion of the array CT image comprises: acquiring a gray compensation reference formula of the array CT imaging system; acquiring a calibration plate image, performing gray compensation on the calibration plate image, and acquiring a distortion elimination characteristic formula of the array CT imaging system; forming an object image according to the array CT imaging system, and performing distortion correction on the object image according to the distortion elimination characteristic formula; The array CT imaging system comprises an X-ray source, a clamping member, and an imaging unit, wherein the X-ray source, the clamping member, and the imaging unit are arranged in sequence on the same straight line. The method for acquiring the gray compensation reference formula of the array CT imaging system comprises: no object imaging, the number of clamped objects on the clamping member is zero, the X-ray source irradiates the imaging unit to form a first image, a first image coordinate system is established on the first image, the coordinate origin of the first image coordinate system coincides with the center point of the first image, and a gray compensation three-dimensional curved surface formula of the first image is acquired; standard metal plate imaging, the clamped object on the clamping member is a standard metal plate, the X-ray source irradiates the standard metal plate to form a second image, a second image coordinate system is established on the second image, the coordinate origin of the second image coordinate system coincides with the center point of the second image, and a gray compensation three-dimensional curved surface formula of the second image is acquired; The method for acquiring the distortion elimination characteristic formula of the array CT imaging system comprises: The clamping member is provided with a standard calibration plate, and the array CT imaging system forms a third image on the standard calibration plate, the standard calibration plate is a metal plate with multiple through holes arranged in an array, the material and thickness of the standard calibration plate are consistent with those of the standard metal plate, and the third image comprises metal plate imaging and multiple features; A third image coordinate system is established on the third image, the coordinate position of the metal plate imaging on the third image has the same gray compensation mode as the corresponding position of the second image in the second image coordinate system, and other coordinate positions on the third image have the same gray compensation mode as the corresponding positions of the first image in the first image coordinate system, thereby realizing gray compensation of the third image to form a third gray compensation image; Image coordinate points of the multiple features are acquired on the third gray compensation image; A world coordinate system is established on the image formed by the orthographic projection of the standard calibration plate on the plane where the third image is located, and world coordinate points corresponding to the image coordinate points of the multiple features in the world coordinate system are acquired; The distortion elimination characteristic formula is acquired according to the image coordinate points and the corresponding world coordinate points.

2. The method of claim 1, wherein, The method for acquiring the distortion elimination characteristic formula according to the image coordinate points and the corresponding world coordinate points comprises: adopting a particle swarm algorithm, fitting the image coordinate points and the corresponding world coordinate points, and acquiring the distortion elimination characteristic formula.

3. The method of removing distortion from a CT image of an array according to claim 1, wherein, Before the distortion correction on the object image according to the distortion elimination characteristic formula, the object image is gray compensated according to the gray compensation reference formula to form a gray compensation image. According to the distortion elimination characteristic formula, the gray compensation image to be imaged is corrected for distortion.

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