WO2023125228A1 - Ct image ring artifact processing method and apparatus, system, and storage medium - Google Patents

Abstract

Embodiments of the present invention relate to the technical field of image processing and provide a CT image ring artifact processing method and apparatus, a system, and a storage medium. The method comprises: acquiring an original CT image; performing first filter processing on the original CT image to extract a ring artifact image in the original CT image; performing first conversion processing on the ring artifact image to obtain a first ring artifact conversion image, and performing second filter processing on the first ring artifact conversion image to obtain a second ring artifact conversion image; performing second conversion processing on the second ring artifact conversion image to obtain a third ring artifact conversion image, the second conversion processing being an inverse process of the first conversion processing; and performing image subtraction processing on the original CT image and the third ring artifact conversion image to obtain a target CT image not comprising a ring artifact. According to the present invention, the accuracy of ring artifact processing is effectively improved, so that a higher-quality artifact-removed image can be obtained, the edge of the image remains intact, and a signal-to-noise ratio is high.

Description

Method, device, system and storage medium for processing ring artifacts in CT images technical field

The present invention relates to the technical field of image processing, in particular to a method for processing ring artifacts in CT images, a processing device for ring artifacts in CT images, a processing system for ring artifacts in CT images, and a machine readable storage media.

Background technique

In geological image analysis, CT (Computed Tomography, computerized tomography) electron microscope scanning is a common method for lithology detection. Due to the defect of the detector pixel element, the error of the ray intensity receiving element, and the nonlinear response of the instrument to the ray energy spectrum, etc., ring artifacts often appear in the CT image, which closely overlap with the image of the tested sample, and appear on the image as A series of concentric circles with different radii centered on the center of the image. The existence of ring artifacts greatly reduces the quality of the image, which brings great troubles to further processing and analysis of image measurement, recognition, noise processing, and image segmentation. Industrial CT scan images containing ring artifacts directly It affects the correct diagnosis of lithology analysis.

Contents of the invention

The purpose of the embodiments of the present invention is to provide a method, device, system and storage medium for processing ring artifacts in CT images, so as to solve the above problems.

In order to achieve the above object, in a first aspect of the present invention, a method for processing ring artifacts in CT images is provided, including:

Acquire raw CT images with ring artifacts;

performing a first filtering process on the original CT image, and extracting a ring artifact image in the original CT image;

performing a first conversion process on the ring artifact image to obtain a first ring artifact converted image, and performing a second filtering process on the first ring artifact converted image to obtain a second ring artifact converted image image;

performing a second conversion process on the second ring artifact converted image to obtain a third ring artifact converted image, the second conversion process being an inverse process of the first conversion process;

performing image subtraction processing on the original CT image and the third ring artifact converted image to obtain a target CT image that does not include ring artifacts.

Optionally, the first filtering process is a non-local mean filtering process; the first filtering process is performed on the original CT image, and the ring artifact image in the original CT image is extracted, including:

performing non-local mean filtering on the original CT image to obtain a background image that does not include ring artifacts;

performing image subtraction processing on the original CT image and the background image to obtain a ring artifact image in the original CT image.

Optionally, the first conversion process is polar coordinate transformation; performing the first conversion process on the ring artifact image to obtain a first ring artifact converted image, including:

Carry out polar coordinate transformation to each pixel of the ring artifact image, and convert the Cartesian coordinates of each pixel into polar coordinates in a polar coordinate system with the isocenter as the origin;

Based on the polar coordinates, each pixel of the ring artifact image is arranged in the polar coordinate system, so as to convert the ring artifact image into a streak artifact image, and the obtained streak artifact Image as the first ringing artifact transformed image.

Optionally, performing a second filtering process on the first ring artifact converted image to obtain a second ring artifact converted image, including:

Constructing a one-dimensional filter in the direction of the horizontal axis of the polar coordinate system, the size of the convolution kernel matrix of the one-dimensional filter is n×m;

Using the one-dimensional filter, sequentially perform Gaussian low-pass filtering on each pixel in the first ring artifact converted image along the horizontal axis of the polar coordinate system to obtain a blurred streak artifact image Transform the image as a second ringing artifact.

Optionally, constructing a one-dimensional filter in the direction of the transverse axis of the polar coordinate system includes:

Acquiring the width of the streaking artifacts in the first ring artifact conversion image, and determining that n is 3 when the width of the streaking artifacts is smaller than a threshold.

Optionally, the second conversion process is Cartesian coordinate transformation; performing the second conversion process on the second ring artifact converted image to obtain a third ring artifact converted image, including:

performing Cartesian coordinate transformation on each pixel of the second ring artifact conversion image, and converting the polar coordinates of each pixel into Cartesian coordinates in a Cartesian coordinate system;

Based on the Cartesian coordinates, each pixel of the second ring artifact converted image is arranged in the Cartesian coordinate system, so as to convert the blurred streak image into a blurred ring artifact image, to obtain The blurred ring artifact image is used as the third ring artifact transformed image.

Optionally, the original CT image is obtained by scanning a full-diameter core.

In a second aspect of the present invention, a device for processing ring artifacts in CT images is provided, including:

A data acquisition module configured to acquire an original CT image with ring artifacts;

An image processing module configured to perform a first filtering process on the original CT image, and extract a ring artifact image in the original CT image;

The first image conversion module is configured to perform a first conversion process on the ring artifact image, obtain a first ring artifact converted image, and perform a second filter process on the first ring artifact converted image , to obtain the second ring artifact transformed image;

The second image conversion module is configured to perform a second conversion process on the second ring artifact converted image to obtain a third ring artifact converted image, and the second conversion process is the first conversion process reverse process;

The artifact removal module is configured to perform image subtraction processing on the original CT image and the third ring artifact converted image to obtain a target CT image that does not include ring artifacts.

In a third aspect of the present invention, a system for processing ring artifacts in CT images is provided, including:

a CT scanning device for performing a CT scan on the target to acquire a raw CT image; and

The above-mentioned device for processing ring artifacts in CT images.

Optionally, the target is a full diameter core.

In a fourth aspect of the present invention, an electronic device is provided, comprising:

a memory storing computer readable instructions;

The processor is configured to read the computer-readable instructions stored in the memory, so as to execute the above method for processing ring artifacts in CT images.

In a fifth aspect of the present invention, a machine-readable storage medium is provided, and instructions are stored on the machine-readable storage medium, and when the instructions are executed by a processor, the processor is configured to execute the above-mentioned CT image loop How to deal with artifacts.

The above technical solution of the present invention transforms the annular artifacts in the rectangular coordinate system into the strip artifacts in the polar coordinate system through the method of coordinate transformation, and then processes the Gaussian low-pass filter to smooth and blur the image, and then uses the coordinate transformation The stripe artifact is converted into a fuzzy ring artifact image, and finally the original ring artifact image is used to subtract the processed fuzzy ring artifact image to obtain a ring artifact-removed image. The present invention effectively improves the ring artifact The accuracy of the shadow processing, the correction of the original CT scan image is more thorough, and a higher-quality artifact-free image can be obtained. The edge of the corrected artifact-free image is completely preserved and has a higher signal-to-noise ratio.

Other features and advantages of the embodiments of the present invention will be described in detail in the following detailed description.

Description of drawings

The accompanying drawings are used to provide a further understanding of the embodiments of the present invention, and constitute a part of the description, together with the following specific embodiments, are used to explain the embodiments of the present invention, but do not constitute limitations to the embodiments of the present invention. In the attached picture:

Fig. 1 is a schematic diagram of an application environment provided by a preferred embodiment of the present invention;

Fig. 2 is the method flowchart of the processing method of CT image ring artifact provided by the preferred embodiment of the present invention;

3 is a schematic block diagram of a processing device for ring artifacts in CT images provided by a preferred embodiment of the present invention;

4 is a schematic block diagram of a processing system for ring artifacts in CT images provided by a preferred embodiment of the present invention;

Fig. 5 is a schematic diagram of an electronic device provided by a preferred embodiment of the present invention.

Detailed ways

Specific embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings. It should be understood that the specific embodiments described here are only used to illustrate and explain the present invention, and are not intended to limit the present invention.

FIG. 1 is a schematic diagram of an application environment of this embodiment, and the application environment includes a CT scanning device 110 , a network 120 and a computer device 130 . The network 120 may be a communication medium of various connection types capable of providing a communication link between the terminal device 110 and the server 130, such as a wired communication link or a wireless communication link. The computer device 130 may be a device with computing capabilities such as a server and a server cluster, which is not specifically limited here.

The CT scanning device 110 is used for performing a CT scan on a target object to obtain a CT scan image. For example, when performing lithology analysis, CT scanning is performed on the rock core sample to obtain a CT scan image of the rock core sample, and then the CT scan image is analyzed to achieve the analysis of the rock core sample. The CT scanning device 110 scans the target object with a certain thickness through X-rays, and the X-rays passing through the target object are received by detectors. Since the target object is composed of a variety of material components, and the density of different material components is different, the absorption coefficient of each point in the target object is different for X-rays. Therefore, the X-rays received by the detector can be calculated for each The attenuation coefficient (or absorption coefficient) of X-rays in each pixel corresponds to the CT scan image of the target object. During this process, ring artifacts will appear in CT scan images due to factors such as defects in detector pixels, errors in ray intensity receiving elements, and the nonlinear response of the instrument to the ray energy spectrum.

The computer device 130 obtains the CT scan image from the CT scan device 110 , and performs filtering, coordinate transformation and other processing on the CT scan image, thereby removing ring artifacts of the CT scan image and obtaining a clear CT scan image. In this way, the application environment composed of the CT scanning device 110 and the computer device 130 can realize the removal of ring artifacts in the CT scanning image, thereby improving the analysis quality of the CT scanning image.

As shown in FIG. 2, in the first aspect of this embodiment, a method for processing ring artifacts in CT images is provided, which is applied to a computer device 130, and the method includes:

S100. Acquire an original CT image with ring artifacts;

S200. Perform a first filtering process on the original CT image, and extract ring artifact images in the original CT image;

S300. Perform first conversion processing on the ring artifact image to obtain a first ring artifact converted image, and perform second filtering processing on the first ring artifact converted image to obtain a second ring artifact converted image;

S400. Perform a second conversion process on the second ring artifact converted image to obtain a third ring artifact converted image, and the second conversion process is an inverse process of the first conversion process;

S500. Perform image subtraction processing on the original CT image and the third ring artifact converted image to obtain a target CT image that does not include ring artifacts.

In this way, in this embodiment, the ring artifacts in the rectangular coordinate system are transformed into strip artifacts in the polar coordinate system through the method of coordinate transformation, and then processed by Gaussian low-pass filtering to smooth and blur the image, and then coordinate transformation The stripe artifact is converted into a fuzzy ring artifact image, and finally the original ring artifact image is used to subtract the processed fuzzy ring artifact image to obtain a ring artifact-removed image. The present invention effectively improves the ring artifact The accuracy of the shadow processing, the correction of the original CT scan image is more thorough, and a higher-quality artifact-free image can be obtained. The edge of the corrected artifact-free image is completely preserved and has a higher signal-to-noise ratio.

In step S100 , the original CT image is obtained by scanning the target object with the CT scanning device 110 , where the original CT image can be obtained by scanning the full-diameter core. Since the original CT image is a digital image formed according to the absorption or attenuation coefficients of X-rays at various points in the target object, affected by factors such as device defects of the CT scanning device 110, ring artifacts usually appear in the original CT image. film. Among them, the ring artifact is the difference between the reconstructed data in the CT image and the actual attenuation coefficient of the target object, or an image that does not exist in the target object but is displayed in the CT image. The existence of ring artifacts makes it difficult for CT images to reflect the influence of real target objects, so it is necessary to process the original CT scan images to remove the ring artifacts.

In step S200, the first filtering process is a non-local mean filtering process; the first filtering process is performed on the original CT image, and the ring artifact image in the original CT image is extracted, including:

S210. Perform non-local mean filter processing on the original CT image to obtain a background image that does not include ring artifacts;

S220. Perform image subtraction processing on the original CT image and the background image to obtain a ring artifact image in the original CT image.

Specifically, the purpose of performing the first filtering process on the original CT image is to separate the background image of the original CT image from the ring artifact, so as to extract the ring artifact from the original CT image to form a ring artifact image.

In a specific example of this embodiment, the first filtering process may use a non-local mean filtering (Non-Local Means, NLM) method to filter the original CT image. The NLM method is an improved filtering algorithm for the traditional neighborhood filtering method, which takes into account the self-similarity of the image, makes full use of the redundant information in the image, and can maintain the details of the image to the greatest extent while denoising. The background image of the original CT image can be obtained by the NLM method, and then the image subtraction process is performed on the original CT image and the scene image, and the original CT image is subtracted from the background image to extract the ring artifacts and obtain the ring artifact. image artifacts.

Specifically, the non-local mean filter algorithm needs to calculate the similarity between all pixels in the image and the current pixel. Considering the calculation amount and efficiency, two fixed-size windows are usually set, and a large search window (D ×D) and a small neighborhood window (d×d). The neighborhood window slides in the search window, and the degree of influence of the corresponding central pixel on the current pixel is determined according to the similarity between the neighborhoods, that is, the weight.

In this embodiment, let the size of the original CT image be M*N, the original CT image is recorded as f={f(i)|i∈Ω}, Ω is the image area in the original CT image, and f(i) represents the original CT The gray value of pixel i in the image. The calculation method of the non-local mean filtering algorithm is as follows:

in,

is the pixel value of pixel i after non-local homogeneous filtering; w(i,j) represents the weight value assigned to the original CT image f(i); a is the standard deviation of the Gaussian kernel function, which is processed by Gaussian kernel image block convolution , which can reduce the influence of noise on distance calculation and highlight the effect of the center of the image block on the pixel; d(i, j) represents the weighted distance between two image blocks; N(i) and N(j) represent the pixel center point is the image block i and the pixel center point is j; h is the filter parameter controlling the degree of smoothness; I represents the search area centered on pixel i.

Since in this embodiment, the non-local mean filtering process adds the weight value of each pixel in the calculation, it can ensure that the mutual influence is reduced when adjacent and very different pixels are averaged in the box , so that the edge details of the image can be better preserved, the sharpness of the image can be effectively improved, and the obtained image quality is better.

In step S300, the first conversion process is polar coordinate transformation; the first conversion process is performed on the ring artifact image to obtain the first ring artifact converted image, including:

S310. Perform polar coordinate transformation on each pixel of the ring artifact image, and convert the rectangular coordinates of each pixel into polar coordinates in a polar coordinate system with the isocenter as the origin;

S320. Based on the polar coordinates, arrange each pixel of the ring artifact image in the polar coordinate system, so as to convert the ring artifact image into a streak artifact image, and use the obtained streak artifact image as the first ring artifact image Artifact transformed image.

The ring artifact image is an image in the Cartesian coordinate system, which is represented as a plurality of concentric circles. In order to make the calculation more convenient, this embodiment first performs polar coordinate transformation on the ring artifact image, and transforms the ring artifact image from Cartesian coordinates are converted to polar coordinates to transform ring artifacts into streak artifacts, also known as line artifacts.

Specifically, the polar coordinate system includes a horizontal axis θ and a vertical axis ρ, the value range of the horizontal axis θ is 0 to 2π, and the value range of the vertical axis ρ is

Among them, M and N are the original CT image size. In order not to lose image information, when determining the pixel values of each point of the image in the polar coordinate system, the ring artifact image is not directly transformed, but the rectangular coordinates are first mapped to polar coordinates, and the mapping method is the polar coordinate system Transformation relationship with Cartesian coordinate system. For a point (x, y) in the rectangular coordinate system, its corresponding polar coordinate system coordinates are (θ, ρ), and the conversion relationship is:

After the polar coordinate transformation, the ring artifact appears as a straight line parallel to the horizontal axis θ of the polar coordinate system in the polar coordinate system, and the ring artifact is converted into a stripe artifact to obtain a stripe artifact image.

In this embodiment, the pixel value of each pixel of the ring artifact image in the polar coordinate system is determined by bilinear interpolation, so as to convert the ring artifact image into a streak artifact image.

Wherein, bilinear interpolation is also called bilinear interpolation. Bilinear interpolation is a linear interpolation extension of the interpolation function with two variables, and its core idea is to perform a linear interpolation in two directions respectively. The pixel value of each pixel in the polar coordinate system of the ring artifact image is determined by bilinear interpolation, that is, the streak artifact image is obtained. In this embodiment, the ring artifact image is converted into a strip artifact image by first performing coordinate system mapping and then bilinear interpolation, which effectively reduces the information loss during the image conversion process, and the bilinear interpolation algorithm enlarges The resulting image quality is high, and there will be no discontinuous pixel values.

In step S300, the second filtering process is carried out to the first ring artifact converted image to obtain the second ring artifact converted image, including:

Construct a one-dimensional filter in the direction of the horizontal axis of the polar coordinate system, and the size of the convolution kernel matrix of the one-dimensional filter is n×m;

Using a one-dimensional filter, sequentially perform Gaussian low-pass filtering on each pixel in the first ring artifact conversion image along the horizontal axis of the polar coordinate system, and obtain the blurred stripe artifact image as the second ring artifact Shadow transform images.

Specifically, digital images are often affected by imaging equipment and external environmental noise interference during the process of formation, transmission, and storage, resulting in noisy images. Noise will affect the image quality, making the post-processing of the image difficult. In order to remove the interference signal in the streak image, that is, to remove the image noise, this embodiment further performs a second filtering process on the streak image. Since the noise removal actually removes some noise information in the striped artifact image, which is equivalent to a certain degree of information loss in the striped artifact image, the image after denoising will be different from the image before denoising. It is blurred, that is, after the second filtering process, a blurred streak artifact image is obtained.

Usually, the second filtering process can use a suitable type of filter for denoising processing, such as mean value filter, adaptive Wiener filter, median filter, morphological noise filter, wavelet denoising and so on. In a specific embodiment of the present application, the second filtering process adopts a Gaussian filter denoising processing method. Gaussian filtering is a process of weighted average of the entire image, and the value of each pixel is obtained by weighted average of itself and other pixel values in the neighborhood. The specific operation of Gaussian filtering is: scan each pixel in the image with a convolution kernel of a set size, and replace the gray value of the center pixel of the convolution kernel with the weighted average gray value of the pixels in the neighborhood determined by the convolution kernel .

In a specific example of this embodiment, a one-dimensional Gaussian low-pass filtering method is used to perform denoising processing on the streak artifact image. First construct a one-dimensional filter in the direction of the horizontal axis θ of the polar coordinate system, and set the matrix size of the convolution kernel to n×m (n is the number of rows of the convolution kernel matrix, and m is the number of columns of the convolution kernel matrix). Among them, the matrix size of the convolution kernel is related to the width of the stripe artifact, and the wider the stripe artifact, the larger the matrix size of the convolution kernel should be set. In this embodiment, when the width of the streak artifact is smaller than the threshold, n≦3 is set, for example, n is preferably 3. Then move the convolution kernel along the horizontal axis θ to scan every pixel in the stripe artifact image. For the value G(x) of the central pixel of the convolution kernel, it is obtained by weighted average of the values of itself and other pixels in the neighborhood, and the calculation method is as follows:

Among them, σ is the standard deviation, also known as the Gaussian radius, and σ2 represents the variance.

When the convolution kernel scans all the pixels in the streak image, image denoising is completed, and a blurred streak image is obtained. The image smoothness of the blurred streak image obtained after denoising in this embodiment is significantly improved, and noise can be effectively reduced at the same time.

In step S400, the second conversion process is Cartesian coordinate transformation; the second conversion process is performed on the second ring artifact converted image to obtain a third ring artifact converted image, including:

S410. Cartesian coordinate transformation is performed on each pixel of the second ring artifact conversion image, and the polar coordinates of each pixel are converted into rectangular coordinates in a rectangular coordinate system;

S420. Based on Cartesian coordinates, arrange each pixel of the second ring artifact converted image into a Cartesian coordinate system, so as to convert the blurred streak image into a blurred ring artifact image, and obtain the blurred ring artifact Image as a third ringing artifact transformed image.

Since the obtained fuzzy strip artifact image is an image in the polar coordinate system, it needs to be inversely transformed into an image in the rectangular coordinate system to obtain a fuzzy ring artifact image. Artifacts in blurred ring artifact images also appear as ring artifacts in Cartesian coordinates. Cartesian coordinate conversion is the inverse process of polar coordinate conversion. For a point (θ, ρ) in the polar coordinate system, its corresponding Cartesian coordinate system coordinates are (x, y). The polar coordinate inverse transformation formula is as follows:

Through the above steps, the ring artifacts in the original CT image are completely extracted. In step S500, subtraction processing is performed on the original CT image and the fuzzy ring artifact image, and the fuzzy ring artifacts are subtracted from the original CT image. image, that is, the ring artifact in the original CT image can be removed to obtain a CT image with the artifact removed.

This embodiment starts with the edge characteristics of ring artifacts, separates them through non-local mean filtering and polar coordinate transformation, and transforms ring artifacts in the Cartesian coordinate system into lines in the polar coordinate system through coordinate transformation. The image is processed by one-dimensional Gaussian low-pass filter to smooth and blur the image, and the processed image is subtracted from the original ring artifact image to get the image without ring artifact, which improves the processing of ring artifact. The accuracy of the original CT scan image is corrected more thoroughly, and a better-quality artifact-free image can be obtained. The edge of the corrected artifact-free image is completely preserved and has a higher signal-to-noise ratio.

As shown in Figure 3, in a second aspect of the present invention, a processing device for ring artifacts in CT images is provided, including:

A data acquisition module configured to acquire an original CT image with ring artifacts;

The image processing module is configured to perform first filtering processing on the original CT image, and extract the ring artifact image in the original CT image;

The first image conversion module is configured to perform a first conversion process on the ring artifact image to obtain a first ring artifact converted image, and perform a second filtering process on the first ring artifact converted image to obtain a second Ring artifact transformed image;

The second image conversion module is configured to perform a second conversion process on the second ring artifact converted image to obtain a third ring artifact converted image, and the second conversion process is an inverse process of the first conversion process;

The artifact removal module is configured to perform image subtraction processing on the original CT image and the third ring artifact converted image to obtain a target CT image that does not include ring artifacts.

As shown in Figure 4, in a third aspect of the present invention, a system for processing ring artifacts in CT images is provided, including:

a CT scanning device for performing a CT scan on the target to acquire a raw CT image; and

The above-mentioned device for processing ring artifacts in CT images. Among them, the target is a full-diameter core.

As shown in FIG. 5, in a fourth aspect of the present invention, an electronic device is provided, including:

a memory storing computer readable instructions;

The processor is configured to read the computer-readable instructions stored in the memory, so as to execute the above method for processing ring artifacts in CT images.

Wherein, the electronic device 600 shown in FIG. 5 is only an example, and should not impose any limitation on the functions and application scope of the embodiment of the present application. As shown in Figure 5, the electronic device 600 includes a central processing unit 601 (Central Processing Unit, CPU), which can be stored in a program in a read-only memory 602 (Read-Only Memory, ROM) or loaded from a storage part 608 to a random Various appropriate actions and processes are executed by accessing programs in the memory 603 (Random Access Memory, RAM). In the random access memory 603, various programs and data necessary for system operation are also stored. The CPU 601 , the read only memory 602 and the random access memory 603 are connected to each other through a bus 604 . An input/output interface 605 (Input/Output interface, ie, an I/O interface) is also connected to the bus 604 .

The following components are connected to the input/output interface 605: an input part 606 including a keyboard, a mouse, etc.; an output part 607 including a cathode ray tube (Cathode Ray Tube, CRT), a liquid crystal display (Liquid Crystal Display, LCD) etc., and a speaker ; a storage section 608 including a hard disk or the like; and a communication section 609 including a network interface card such as a LAN card, a modem, or the like. The communication section 609 performs communication processing via a network such as the Internet. A driver 610 is also connected to the input/output interface 605 as needed. A removable medium 611 such as a magnetic disk, an optical disk, a magneto-optical disk, a semiconductor memory, etc. is mounted on the drive 610 as necessary so that a computer program read therefrom is installed into the storage section 608 as necessary.

In particular, according to the embodiments of the present application, the processes described in the respective method flowcharts can be implemented as computer software programs. For example, the embodiments of the present application include a computer program product, which includes a computer program carried on a computer-readable medium, where the computer program includes program codes for executing the methods shown in the flowcharts. In such an embodiment, the computer program may be downloaded and installed from a network via communication portion 609 and/or installed from removable media 611 . When the computer program is executed by the central processing unit 601, various functions defined in the system of the present application are performed.

Through the description of the above implementations, those skilled in the art can easily understand that the example implementations described here can be implemented by software, or by combining software with necessary hardware. Therefore, the technical solutions according to the embodiments of the present application can be embodied in the form of software products, which can be stored in a non-volatile storage medium (which can be CD-ROM, U disk, mobile hard disk, etc.) or on the network , including several instructions to make a computing device (which may be a personal computer, server, terminal device, or network device, etc.) execute the method according to the embodiment of the present application.

In a fifth aspect of the present invention, a machine-readable storage medium is provided, and instructions are stored on the machine-readable storage medium. When the instructions are executed by a processor, the processor is configured to perform the above CT image ring pseudo Shadow processing method.

Machine-readable storage media includes both volatile and non-volatile, removable and non-removable media that may be implemented by any method or technology for storage of information. Information may be computer readable instructions, data structures, modules of a program, or other data. Examples of computer storage media include, but are not limited to, phase change memory (PRAM), static random access memory (SRAM), dynamic random access memory (DRAM), other types of random access memory (RAM), read only memory (ROM), Electrically Erasable Programmable Read-Only Memory (EEPROM), Flash memory or other memory technology, Compact Disc Read-Only Memory (CD-ROM), Digital Versatile Disc (DVD) or other optical storage, Magnetic tape cartridge, tape magnetic disk storage or other magnetic storage device or any other non-transmission medium that can be used to store information that can be accessed by a computing device. As defined herein, computer-readable media excludes transitory computer-readable media, such as modulated data signals and carrier waves.

The present application is described with reference to flowcharts and/or block diagrams of methods, apparatus (systems), and computer program products according to embodiments of the present application. It should be understood that each procedure and/or block in the flowchart and/or block diagram, and a combination of procedures and/or blocks in the flowchart and/or block diagram can be realized by computer program instructions. These computer program instructions may be provided to a general purpose computer, special purpose computer, embedded processor, or processor of other programmable data processing equipment to produce a machine such that the instructions executed by the processor of the computer or other programmable data processing equipment produce a An apparatus for realizing the functions specified in one or more procedures of the flowchart and/or one or more blocks of the block diagram.

These computer program instructions may also be stored in a computer-readable memory capable of directing a computer or other programmable data processing apparatus to operate in a specific manner, such that the instructions stored in the computer-readable memory produce an article of manufacture comprising instruction means, the instructions The device realizes the function specified in one or more procedures of the flowchart and/or one or more blocks of the block diagram.

These computer program instructions can also be loaded onto a computer or other programmable data processing device, causing a series of operational steps to be performed on the computer or other programmable device to produce a computer-implemented process, thereby The instructions provide steps for implementing the functions specified in the flow chart or blocks of the flowchart and/or the block or blocks of the block diagrams.

It should also be noted that the term "comprises", "comprises" or any other variation thereof is intended to cover a non-exclusive inclusion such that a process, method, article, or apparatus comprising a set of elements includes not only those elements, but also includes Other elements not expressly listed, or elements inherent in the process, method, commodity, or apparatus are also included. Without further limitations, an element qualified by the phrase "comprising a..." does not preclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.

The optional embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings. However, the embodiments of the present invention are not limited to the specific details in the above-mentioned embodiments. Within the technical concept of the embodiments of the present invention, the technical aspects of the embodiments of the present invention can be Various simple modifications are made to the scheme, and these simple modifications all belong to the protection scope of the embodiments of the present invention.

In addition, it should be noted that the various specific technical features described in the above specific implementation manners may be combined in any suitable manner if there is no contradiction. In order to avoid unnecessary repetition, various possible combinations are not further described in the embodiments of the present invention.

In addition, any combination of various implementations of the present invention can also be made, as long as they do not violate the idea of the implementations of the present invention, they should also be regarded as the content disclosed in the implementations of the present invention.

Claims (12)

1. A method for processing ring artifacts in CT images, comprising:

   Acquire raw CT images with ring artifacts;

   performing a first filtering process on the original CT image, and extracting a ring artifact image in the original CT image;

   performing a first conversion process on the ring artifact image to obtain a first ring artifact converted image, and performing a second filtering process on the first ring artifact converted image to obtain a second ring artifact converted image image;

   performing a second conversion process on the second ring artifact converted image to obtain a third ring artifact converted image, the second conversion process being an inverse process of the first conversion process;

   performing image subtraction processing on the original CT image and the third ring artifact converted image to obtain a target CT image that does not include ring artifacts.
2. The method for processing ring artifacts in CT images according to claim 1, wherein the first filtering process is a non-local mean filtering process;

   Carrying out the first filtering process on the original CT image, extracting the ring artifact image in the original CT image, including:

   performing non-local mean filtering on the original CT image to obtain a background image that does not include ring artifacts;

   performing image subtraction processing on the original CT image and the background image to obtain a ring artifact image in the original CT image.
3. The method for processing ring artifacts in CT images according to claim 1, wherein the first transformation process is polar coordinate transformation;

   Performing the first conversion process on the ring artifact image to obtain the first ring artifact converted image, including:

   Carry out polar coordinate transformation to each pixel of the ring artifact image, and convert the Cartesian coordinates of each pixel into polar coordinates in a polar coordinate system with the isocenter as the origin;

   Based on the polar coordinates, each pixel of the ring artifact image is arranged in the polar coordinate system, so as to convert the ring artifact image into a streak artifact image, and the obtained streak artifact Image as the first ringing artifact transformed image.
4. The method for processing ring artifacts in CT images according to claim 3, wherein the second filtering process is performed on the first converted image of ring artifacts to obtain a second converted image of ring artifacts, comprising:

   Constructing a one-dimensional filter in the direction of the horizontal axis of the polar coordinate system, the size of the convolution kernel matrix of the one-dimensional filter is n×m;

   Using the one-dimensional filter, sequentially perform Gaussian low-pass filtering on each pixel in the first ring artifact converted image along the horizontal axis of the polar coordinate system to obtain a blurred streak artifact image Transform the image as a second ringing artifact.
5. The processing method of CT image ring artifacts according to claim 4, characterized in that, constructing a one-dimensional filter in the direction of the transverse axis of the polar coordinate system comprises:

   Acquiring the width of the streaking artifacts in the first ring artifact conversion image, and determining that n is 3 when the width of the streaking artifacts is smaller than a threshold.
6. The method for processing ring artifacts in CT images according to claim 4, wherein the second transformation process is Cartesian coordinate transformation;

   Performing a second conversion process on the second ring artifact converted image to obtain a third ring artifact converted image, including:

   performing Cartesian coordinate transformation on each pixel of the second ring artifact conversion image, and converting the polar coordinates of each pixel into Cartesian coordinates in a Cartesian coordinate system;

   Based on the Cartesian coordinates, each pixel of the second ring artifact converted image is arranged in the Cartesian coordinate system, so as to convert the blurred streak image into a blurred ring artifact image, to obtain The blurred ring artifact image is used as the third ring artifact transformed image.
7. The method for processing ring artifacts in CT images according to claim 1, wherein the original CT image is obtained by scanning a full-diameter rock core.
8. A processing device for CT image ring artifacts, characterized in that it comprises:

   A data acquisition module configured to acquire an original CT image with ring artifacts;

   An image processing module configured to perform a first filtering process on the original CT image, and extract a ring artifact image in the original CT image;

   The first image conversion module is configured to perform a first conversion process on the ring artifact image, obtain a first ring artifact converted image, and perform a second filter process on the first ring artifact converted image , to obtain the second ring artifact transformed image;

   The second image conversion module is configured to perform a second conversion process on the second ring artifact converted image to obtain a third ring artifact converted image, and the second conversion process is the first conversion process reverse process;

   The artifact removal module is configured to perform image subtraction processing on the original CT image and the third ring artifact converted image to obtain a target CT image that does not include ring artifacts.
9. A processing system for CT image ring artifacts, characterized in that it comprises:

   a CT scanning device for performing a CT scan on the target to acquire a raw CT image; and

   The device for processing ring artifacts in CT images according to claim 8.
10. The system for processing ring artifacts in CT images according to claim 9, wherein the target is a full-diameter rock core.
11. An electronic device, characterized in that it comprises:

    a memory storing computer readable instructions;

    The processor is configured to read computer-readable instructions stored in the memory, so as to execute the method for processing ring artifacts in CT images according to any one of claims 1 to 7.
12. A machine-readable storage medium, the machine-readable storage medium stores instructions, which is characterized in that, when the instructions are executed by a processor, the processor is configured to perform any one of claims 1 to 7 The method for processing ring artifacts in CT images is required.

Images