Space domain filter function generation method and device for ISAR image inverse transform

Abstract

The application provides a method and device for generating a spatial domain filter function for ISAR image inverse transformation, wherein the method comprises: constructing a unit image matrix based on a target ISAR image; wherein the coordinate dimensions corresponding to the unit image matrix are the same as the coordinate dimensions of the target ISAR image, and each element in the unit image matrix is unit 1; performing the same operation processing procedure on the unit image matrix based on the operation processing procedure required for the target ISAR image, to obtain an initial spatial domain filter function; inversely transforming the initial spatial domain filter function to an angle-frequency domain to obtain a similar angle-frequency domain function; performing window processing on the similar angle-frequency function in the angle and frequency dimensions by using a window function; and performing two-dimensional ISAR imaging on the function after the window processing, to obtain a final spatial domain filter function. According to the scheme, the generated spatial domain filter function can reduce the spectrum leakage of the transition region after ISAR image processing.

Description

Technical Field

[0001] This invention relates to the field of data processing technology, and in particular to a method and apparatus for generating spatial filtering functions for inverse ISAR image transformation. Background Technology

[0002] In target characteristic analysis, stealth performance evaluation, and typical component optimization design, the assessment of the target's local radar scattering characteristics plays a crucial role. Accurate analysis of local scattering characteristics and their contribution to the overall radar cross section (RCS) can significantly optimize the design process of typical stealth structures and components. In local scattering characteristic assessment, spatial filters are typically used to process ISAR (Inverse Synthetic Aperture Radar) images. The quality of the spatial filter function directly impacts the error magnitude of the subsequent angular and frequency domain RCS data obtained from the inverse transformation of the ISAR image. Therefore, to obtain accurate target local RCS characteristics, it is necessary to specifically design the spatial filter function.

[0003] Currently, spatial filtering functions are generally constructed based on the processing method of the ISAR image to be processed. However, the spatial filtering functions constructed in existing technologies cause severe spectral leakage in the transition region when processing ISAR images, making the subsequent normalization process difficult. Therefore, there is a need to provide a new method for generating spatial filtering functions for inverse ISAR image transformation, so that the designed spatial filtering function can reduce spectral leakage in the transition region after processing ISAR images. Summary of the Invention

[0004] This invention provides a method and apparatus for generating spatial filtering functions for inverse ISAR image transformation, which enables the generated spatial filtering function to reduce spectral leakage in transition regions after ISAR image processing.

[0005] In a first aspect, embodiments of the present invention provide a method for generating spatial filtering functions for inverse ISAR image transform, comprising:

[0006] A unit image matrix is ​​constructed based on the target ISAR image; wherein the coordinate dimension of the unit image matrix is ​​the same as the coordinate dimension of the target ISAR image, and each element in the unit image matrix is ​​a unit 1;

[0007] Based on the required processing flow for the target ISAR image, the same processing flow is performed on the unit image matrix to obtain the initial spatial filtering function.

[0008] The initial spatial domain filtering function is inversely transformed to the angle-frequency domain to obtain a function similar to the angle-frequency domain.

[0009] The angle-frequency function is windowed in both the angle and frequency dimensions using a window function.

[0010] The windowed function is then used for two-dimensional ISAR imaging to obtain the final spatial filtering function.

[0011] In one possible implementation, the step of inversely transforming the initial spatial domain filtering function to the angle-frequency domain to obtain a quasi-angle-frequency function includes:

[0012] The initial spatial domain filter function is transformed from the spatial domain to the corresponding (f) using a two-dimensional Fourier transform. x ,f y ) domain, to obtain (f x ,f y Domain functions;

[0013] f x ,f y The domain function is mapped to the XOY plane to obtain a quasi-angle-frequency domain function.

[0014] In one possible implementation, (f) is obtained using the following formula. x ,f y Domain function:

[0015] Gate(f x ,f y )=∫∫gate(x,y)exp[-j2π(f x x+f y y)]dxdy

[0016]

[0017]

[0018] Among them, Gate(f x ,f y ) is (f x ,f y The initial spatial domain filtering function is defined by gate(x,y), f is defined by frequency in the angle-frequency domain, θ is defined by angle in the angle-frequency domain, and c is defined by speed of light.

[0019] In one possible implementation, the main lobe width of the window function is no greater than 8π, and the maximum side lobe amplitude of the window function is less than -40dB.

[0020] In one possible implementation, performing two-dimensional ISAR imaging on the windowed function includes:

[0021] The windowed function is subjected to an inverse Fourier transform along the frequency dimension on an angle-by-angle basis to obtain the target range profile.

[0022] The target range image is mapped onto a two-dimensional imaging plane, and the mapping at different angles is integrated to obtain the final spatial filtering function.

[0023] In one possible implementation, before mapping the target range image to the two-dimensional imaging plane, the method further includes: selecting a target region from the target range image to obtain a filtered target range image, and then mapping the filtered target range image to the two-dimensional imaging plane.

[0024] In one possible implementation, the inverse Fourier transform of the windowed function, processed angle by angle, is performed in the frequency dimension using the following formula:

[0025]

[0026] in, Used to characterize the target range image, Used to characterize the function after windowing. The wavenumber is used to characterize the wave number, f is used to characterize the frequency in the angle-frequency domain, θ is used to characterize the angle in the angle-frequency domain, c is used to characterize the speed of light, and r is used to characterize the polar radius. Used to characterize the observation angle;

[0027] The mapping of the target range image to the two-dimensional imaging plane is performed based on the following mapping relationship:

[0028] spatial domain

[0029] The integration of the mapping at different angles is performed using the following formula:

[0030]

[0031] in, Used to characterize the final spatial filtering function.

[0032] Secondly, embodiments of the present invention also provide a spatial filtering function generation apparatus for ISAR image inverse transform, comprising:

[0033] A matrix construction unit is used to construct a unit image matrix based on a target ISAR image; wherein the coordinate dimension of the unit image matrix is ​​the same as the coordinate dimension of the target ISAR image, and each element in the unit image matrix is ​​a unit 1;

[0034] The matrix processing unit is used to perform the same operation and processing flow on the unit image matrix based on the operation and processing flow required for the target ISAR image, so as to obtain the initial spatial domain filtering function.

[0035] The inverse transform unit is used to inversely transform the initial spatial domain filter function to the angle-frequency domain to obtain a function similar to the angle-frequency domain.

[0036] A windowing processing unit is used to apply windowing to the angle-frequency function in both angle and frequency dimensions using a window function.

[0037] The imaging unit is used to perform two-dimensional ISAR imaging on the windowed function to obtain the final spatial filtering function.

[0038] Thirdly, embodiments of the present invention also provide an electronic device, including a memory and a processor, wherein the memory stores a computer program, and when the processor executes the computer program, it implements the method described in any embodiment of this specification.

[0039] Fourthly, embodiments of the present invention also provide a computer-readable storage medium having a computer program stored thereon, which, when executed in a computer, causes the computer to perform the methods described in any embodiment of this specification.

[0040] This invention provides a method and apparatus for generating spatial filtering functions for inverse ISAR image transformation. After deriving an initial spatial filtering function based on the required processing flow of the target ISAR image, the initial spatial filtering function is inversely transformed to the angle-frequency domain to obtain a quasi-angle-frequency domain function. A window function is then used to window the quasi-angle-frequency domain function in both angle and frequency dimensions. Finally, the windowed function is subjected to two-dimensional ISAR imaging, thus obtaining the final designed spatial filtering function. In this scheme, since ISAR images have many possible processing styles, using a window function to design a two-dimensional spatial filtering function ensures that when the designed spatial filtering function processes the target ISAR image, transition regions are smoothed, and the filtering requirements for different regions of the ISAR image are met, thereby reducing spectral leakage in transition regions. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a flowchart of a spatial filtering function generation method for ISAR image inverse transform provided by an embodiment of the present invention;

[0043] Figure 2 This is a hardware architecture diagram of an electronic device provided in an embodiment of the present invention;

[0044] Figure 3 This is a structural diagram of a spatial filtering function generation device for ISAR image inverse transform provided in an embodiment of the present invention. Detailed Implementation

[0045] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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 some embodiments of the present invention, but not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0046] Please refer to Figure 1 This invention provides a method for generating spatial filtering functions for inverse ISAR image transform, the method comprising:

[0047] Step 100: Construct a unit image matrix based on the target ISAR image; wherein the coordinate dimension of the unit image matrix is ​​the same as the coordinate dimension of the target ISAR image, and each element in the unit image matrix is ​​a unit 1;

[0048] Step 102: Based on the required operation process of the target ISAR image, perform the same operation process on the unit image matrix to obtain the initial spatial filtering function;

[0049] Step 104: Inverse transform the initial spatial domain filtering function to the angle-frequency domain to obtain a function similar to the angle-frequency domain;

[0050] Step 106: Apply a window function to the angle-frequency function in both the angle and frequency dimensions.

[0051] Step 108: Perform two-dimensional ISAR imaging on the windowed function to obtain the final spatial filtering function.

[0052] In this embodiment of the invention, after obtaining the initial spatial filtering function based on the required operational processing flow of the target ISAR image, the initial spatial filtering function is inversely transformed to the angle-frequency domain to obtain a quasi-angle-frequency domain function. A window function is then used to window the quasi-angle-frequency domain function in both angle and frequency dimensions. Finally, the windowed function is used for two-dimensional ISAR imaging, thus obtaining the final designed spatial filtering function. In this scheme, since there are many possible processing styles for ISAR images, using a window function to design a two-dimensional spatial filtering function ensures that when the designed spatial filtering function processes the target ISAR image, transition regions are smoothed, and the filtering requirements for different regions of the ISAR image are met, thereby reducing spectral leakage in transition regions.

[0053] The following description Figure 1 The execution method for each step is shown.

[0054] First, the following steps are explained: "Construct a unit image matrix based on the target ISAR image; wherein the coordinate dimension of the unit image matrix is ​​the same as the coordinate dimension of the target ISAR image, and each element in the unit image matrix is ​​a unit 1" and "Perform the same operation and processing flow on the unit image matrix based on the operation and processing flow required for the target ISAR image to obtain the initial spatial filtering function".

[0055] The unit image matrix ones(x,y) is identical to the target ISAR image in the x and y dimensions. For example, if the target ISAR image has m*n pixels, then the unit image matrix has m*n elements.

[0056] Since the spatial filtering function generated in this embodiment is used to process the target ISAR image, the unit image matrix needs to undergo the same processing procedure as the target ISAR image. For example, this processing procedure might be: first, perform corner attenuation, then select a region, and finally perform an eraser operation. Therefore, the unit image matrix needs to undergo the same processing procedure to obtain the initial spatial filtering function, denoted as gate(x,y).

[0057] Then, for step 104, the initial spatial domain filtering function is inversely transformed to the angle-frequency domain to obtain a function similar to the angle-frequency domain.

[0058] Since the image is located in a Cartesian coordinate plane, in this embodiment of the invention, the method of inversely transforming the initial spatial domain filter function to the angle-frequency domain may include:

[0059] The initial spatial domain filter function is transformed from the spatial domain to the corresponding (f) using a two-dimensional Fourier transform.x ,f y ) domain, to obtain (f x ,f y Domain functions;

[0060] (f) x ,f y The domain function is mapped to the XOY plane to obtain the angle-frequency domain function Gate(f,θ).

[0061] The formula for the two-dimensional Fourier transform is:

[0062] Gate(f x ,f y )=∫∫gate(x,y)exp[-j2π(f x x+f y y)]dxdy

[0063]

[0064]

[0065] Among them, Gate(f x ,f y ) is (f x ,f y The θ-frequency domain function is used to characterize the frequency in the angle-frequency domain, θ is used to characterize the angle in the angle-frequency domain, and c is used to characterize the speed of light.

[0066] In (f) x ,f y When mapping a domain function to the XOY plane, the above f can be used. x Formula and f y The formula is mapped. Spline interpolation can be used to implement this mapping process.

[0067] It should be noted that f and θ are the frequency and angle to be transformed. For example, f can be several values ​​between 9 GHz and 11 GHz, and θ can be several values ​​between -10° and 10°. The transformation to the angle-frequency domain can include multiple combinations, and these combinations are different from each other.

[0068] Then, for step 106, the angle-frequency function is windowed in both the angle and frequency dimensions using a window function.

[0069] In one embodiment of the present invention, the window function can be a Hamming window, a BlackMan window, a Kaiser window, or a custom window function.

[0070] In order to ensure that the spatial filtering function obtained after processing with the window function can meet the requirements, the selection of the window function should include at least the following two principles: (1) the main lobe of the window spectrum should be as narrow as possible in order to obtain a steeper transition band; (2) the relative amplitude of the maximum side lobe of the window function should be minimized, that is, the energy should be concentrated in the main lobe of the window function as much as possible, so that the peaks and ripples are reduced, and the attenuation of the stopband can be increased.

[0071] Based on the above two principles, in one embodiment of the present invention, the main lobe width of the window function is no greater than 8π, and the maximum side lobe amplitude of the window function is less than -40dB.

[0072] For example, using the Hamming window as the window function, the main lobe width of the Hamming window is 8π / N, which makes the precise transition bandwidth reach 6.6π / N and the minimum stopband attenuation reach 53dB.

[0073] The formula for windowing can be expressed as:

[0074]

[0075] in, W(f,θ) is used to characterize the windowed function.

[0076] Then, for step 108, the windowed function is subjected to two-dimensional ISAR imaging to obtain the final spatial filtering function.

[0077] The purpose of performing 2D ISAR imaging on the windowed function is to transform the windowed function back into the spatial domain. The 2D ISAR imaging method is the same as the target ISAR image imaging method, which ensures that the final spatial filtering function obtained after 2D ISAR imaging can accurately process the target ISAR image.

[0078] In one embodiment of the present invention, step 108 may include:

[0079] S1. Perform an inverse Fourier transform on the windowed function at each angle along the frequency dimension to obtain the target range image;

[0080] Specifically, the inverse Fourier transform of the windowed function, processed angle by angle, is performed in the frequency dimension using the following formula:

[0081]

[0082] in, Used to characterize the target range image, Used to characterize the function after windowing. The wavenumber is used to characterize the wave number, f is used to characterize the frequency in the angle-frequency domain, θ is used to characterize the angle in the angle-frequency domain, c is used to characterize the speed of light, and r is used to characterize the polar radius. Used to characterize the observation angle.

[0083] S2. Map the target range image onto the two-dimensional imaging plane, and integrate the mapping at different angles to obtain the final spatial filtering function.

[0084] Specifically, the mapping of the target range image to the two-dimensional imaging plane is performed based on the following mapping relationship:

[0085] spatial domain

[0086] The integration of the mapping at different angles is performed using the following formula:

[0087]

[0088] in, Used to characterize the final spatial filtering function.

[0089] Furthermore, since the edge regions corresponding to the target range images obtained by performing an inverse Fourier transform on the frequency dimension angle by angle have deviations, in order to ensure that the image region obtained after mapping the target range image to the two-dimensional imaging plane is without deviation, the process between steps S1 and S2 further includes: selecting the target region from the target range image to obtain a filtered target range image; and using the filtered target range image as the target range image in S2 to perform mapping to the two-dimensional imaging plane. Here, the target region is the middle part of the region. This makes the final spatial filtering function more accurate.

[0090] In this embodiment, the filtered target range image gate(r|θ) is projected onto the two-dimensional imaging plane through the mapping relationship between (x,y) and (r,θ). Then, the mapping results at different angles are integrated using the aforementioned integral formula to obtain the two-dimensional image of the target, which is the final spatial filtering function. This yields the final spatial filtering function, which is used to process the target ISAR image, thereby reducing spectral leakage in transition regions.

[0091] In this embodiment of the invention, the window function method is used to design a two-dimensional spatial filter, which allows for more flexible selection of the window function. If the principle of window function selection is well grasped, the transition band of the designed two-dimensional spatial filter will be as steep as possible, and the peaks and ripples will be reduced while the attenuation of the stopband will be increased. In addition, since there are various ways to process ISAR images, the window function method can quickly generate two-dimensional spatial filters of different styles without changing the processing method.

[0092] like Figure 2 , Figure 3 As shown, this invention provides a spatial filtering function generation device for ISAR image inverse transform. The device can be implemented in software, hardware, or a combination of both. From a hardware perspective, as... Figure 2 The diagram shown is a hardware architecture diagram of an electronic device for generating spatial filtering functions for ISAR image inverse transform, provided in an embodiment of the present invention. (Except for...) Figure 2 In addition to the processor, memory, network interface, and non-volatile memory shown, the electronic device in the embodiment may also include other hardware, such as a forwarding chip responsible for processing packets. Taking software implementation as an example, such as... Figure 3 As shown, as a logical device, it is formed by the CPU of its electronic device reading the corresponding computer program from the non-volatile memory into memory and running it. This embodiment provides a spatial filtering function generation device for ISAR image inverse transform, comprising:

[0093] The matrix construction unit 301 is used to construct a unit image matrix based on the target ISAR image; wherein the coordinate dimension of the unit image matrix is ​​the same as the coordinate dimension of the target ISAR image, and each element in the unit image matrix is ​​a unit 1;

[0094] The matrix processing unit 302 is used to perform the same operation processing flow on the unit image matrix based on the operation processing flow required for the target ISAR image to obtain the initial spatial domain filtering function.

[0095] Inverse transformation unit 303 is used to inversely transform the initial spatial domain filtering function to the angle-frequency domain to obtain a function similar to the angle-frequency domain.

[0096] The windowing processing unit 304 is used to apply windowing processing to the angle-frequency function in both the angle and frequency dimensions using a window function.

[0097] Imaging unit 305 is used to perform two-dimensional ISAR imaging on the windowed function to obtain the final spatial filtering function.

[0098] In one embodiment of the present invention, the inverse transform unit 303 is specifically used to: transform the initial spatial domain filter function from the spatial domain to the corresponding (f) using a two-dimensional Fourier transform. x ,f y ) domain, to obtain (f x ,f y ) domain function; to make the (f x ,f yThe domain function is mapped to the XOY plane to obtain a quasi-angle-frequency domain function.

[0099] In one embodiment of the present invention, (f) is obtained using the following formula. x ,f y Domain function:

[0100] Gate(f x ,f y )=∫∫gate(x,y)exp[-j2π(f x x+f y y)]dxdy

[0101]

[0102]

[0103] Among them, Gate(f x ,f y ) is (f x ,f y The initial spatial domain filtering function is defined by gate(x,y), f is defined by frequency in the angle-frequency domain, θ is defined by angle in the angle-frequency domain, and c is defined by speed of light.

[0104] In one embodiment of the present invention, the main lobe width of the window function is no greater than 8π, and the maximum side lobe amplitude of the window function is less than -40dB.

[0105] In one embodiment of the present invention, the imaging unit 305 is specifically used to: perform an inverse Fourier transform on the windowed function at each angle in the frequency dimension to obtain a target range image; map the target range image onto a two-dimensional imaging plane, and integrate the mapping at different angles to obtain the final spatial filtering function.

[0106] In one embodiment of the present invention, the imaging unit 305 is further configured to select a target region from the target range image to obtain a filtered target range image, and to perform the mapping of the filtered target range image onto a two-dimensional imaging plane.

[0107] In one embodiment of the present invention, the inverse Fourier transform of the windowed function processed angle by angle is performed in the frequency dimension using the following formula:

[0108]

[0109] in, Used to characterize the target range image, Used to characterize the function after windowing. The wavenumber is used to characterize the wave number, f is used to characterize the frequency in the angle-frequency domain, θ is used to characterize the angle in the angle-frequency domain, c is used to characterize the speed of light, and r is used to characterize the polar radius. Used to characterize the observation angle;

[0110] The mapping of the target range image to the two-dimensional imaging plane is performed based on the following mapping relationship:

[0111] spatial domain

[0112] The integration of the mapping at different angles is performed using the following formula:

[0113]

[0114] in, Used to characterize the final spatial filtering function.

[0115] It is understood that the structures illustrated in the embodiments of the present invention do not constitute a specific limitation on a spatial filtering function generation device for ISAR image inverse transform. In other embodiments of the present invention, a spatial filtering function generation device for ISAR image inverse transform may include more or fewer components than illustrated, or combine some components, split some components, or arrange different components. The illustrated components may be implemented in hardware, software, or a combination of software and hardware.

[0116] The information interaction and execution process between the modules in the above-mentioned device are based on the same concept as the method embodiment of the present invention, and the specific details can be found in the description of the method embodiment of the present invention, and will not be repeated here.

[0117] This invention also provides an electronic device, including a memory and a processor. The memory stores a computer program, and when the processor executes the computer program, it implements a spatial filtering function generation method for ISAR image inverse transform according to any embodiment of this invention.

[0118] This invention also provides a computer-readable storage medium storing a computer program. When executed by a processor, the computer program causes the processor to perform a spatial filtering function generation method for ISAR image inverse transform according to any embodiment of this invention.

[0119] Specifically, a system or apparatus equipped with a storage medium may be provided, on which software program code implementing the functions of any of the embodiments described above is stored, and the computer (or CPU or MPU) of the system or apparatus may read and execute the program code stored in the storage medium.

[0120] In this case, the program code read from the storage medium can itself implement the function of any of the above embodiments, and therefore the program code and the storage medium storing the program code constitute part of the present invention.

[0121] Examples of storage media used to provide program code include floppy disks, hard disks, magneto-optical disks, optical disks (such as CD-ROM, CD-R, CD-RW, DVD-ROM, DVD-RAM, DVD-RW, DVD+RW), magnetic tapes, non-volatile memory cards, and ROMs. Alternatively, program code can be downloaded from a server computer via a communication network.

[0122] Furthermore, it should be clear that not only can the program code read by the computer be executed, but also the operating system or other components operating on the computer can be instructed based on the program code to perform some or all of the actual operations, thereby realizing the function of any of the embodiments described above.

[0123] Furthermore, it is understood that the program code read from the storage medium is written to the memory set in the expansion board inserted into the computer or to the memory set in the expansion module connected to the computer. Then, based on the instructions of the program code, the CPU or other components installed on the expansion board or expansion module execute some and all of the actual operations, thereby realizing the function of any of the above embodiments.

[0124] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.

[0125] Those skilled in the art will understand that all or part of the steps of the above method embodiments can be implemented by hardware related to program instructions. The aforementioned program can be stored in a computer-readable storage medium. When the program is executed, it performs the steps of the above method embodiments. The aforementioned storage medium includes various media that can store program code, such as ROM, RAM, magnetic disk, or optical disk.

[0126] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for generating a spatial filter function for ISAR image inverse transform, characterized in that, The method comprises the following steps: constructing a unit image matrix based on a target ISAR image; wherein the coordinate dimensions corresponding to the unit image matrix are the same as the coordinate dimensions of the target ISAR image, and each element in the unit image matrix is a unit 1; performing the same operation processing procedure on the unit image matrix based on an operation processing procedure required by the target ISAR image to obtain an initial spatial domain filter function; inverse transforming the initial spatial domain filter function to an angle-frequency domain to obtain an angle-frequency-like function; performing window processing on the angle-frequency-like function in the angle and frequency dimensions by using a window function; performing two-dimensional ISAR imaging on the function after the window processing to obtain a final spatial domain filter function; the final spatial domain filter function is used for processing the target ISAR image.

2. The method of claim 1, wherein, The inverse transforming the initial spatial domain filter function to the angle-frequency domain to obtain the angle-frequency-like function comprises: The initial spatial domain filter function is transformed from spatial domain to corresponding (f x ,f y ) domain by using two-dimensional Fourier transform, to obtain (f x ,f y ) domain function; The (f x ,f y ) domain function is mapped to the XOY plane to obtain an angle-like frequency domain function.

3. The method according to claim 2, characterized in that, The (f x ,f y ) domain function is obtained using the following equation: Gate(f x ,f y ) = ∫∫ gate(x,y) exp[-j2π(f x x + f y y)] dxdy where Gate(f x ,f y ) is a (f x ,f y )-domain function, gate(x,y) is used to represent the initial spatial domain filter function, f is used to represent the frequency in the angle-frequency domain, θ is used to represent the angle in the angle-frequency domain, and c is used to represent the speed of light.

4. The method of claim 1, wherein, the main lobe width of the window function is not greater than 8π, and the maximum side lobe amplitude of the window function is lower than -40db.

5. The method of claim 1, wherein, The performing two-dimensional ISAR imaging on the function after the window processing comprises: performing inverse Fourier transform on the function after the window processing in the frequency dimension by angle to obtain a target range image; mapping the target range image to a two-dimensional imaging plane, and integrating the mappings on different angles to obtain the final spatial domain filter function.

6. The method of claim 5, wherein, Before the mapping the target range image to the two-dimensional imaging plane, the method further comprises: obtaining a filtered target range image by selecting a target region in the target range image, and performing the mapping to the two-dimensional imaging plane on the filtered target range image.

7. The method according to claim 5, characterized in that, the performing inverse Fourier transform on the function after the window processing in the frequency dimension by angle is performed by using the following formula: wherein, for characterizing a target distance image, for characterizing a windowed function, for characterizing a wave number, f for characterizing a frequency of an angle-frequency domain, θ for characterizing an angle of an angle-frequency domain, c for characterizing a speed of light, r for characterizing a polar coordinate radius, for characterizing an observation angle; the mapping the target range image to the two-dimensional imaging plane is performed based on the following mapping relationship: the integrating the mappings on different angles is performed by using the following formula: wherein for characterizing the final spatial filter function.

8. An apparatus for generating a spatial domain filter function for ISAR image inverse transform, characterized in that, The method for implementing any one of the above claims 1-7 comprises: a matrix construction unit configured to construct a unit image matrix based on a target ISAR image; wherein the coordinate dimensions corresponding to the unit image matrix are the same as the coordinate dimensions of the target ISAR image, and each element in the unit image matrix is a unit 1; a matrix processing unit configured to perform the same operation processing procedure on the unit image matrix based on an operation processing procedure required by the target ISAR image to obtain an initial spatial domain filter function; an inverse transformation unit configured to inverse transform the initial spatial domain filter function to an angle-frequency domain to obtain an angle-frequency-like function; a window processing unit configured to perform window processing on the angle-frequency-like function in the angle and frequency dimensions by using a window function; an imaging unit configured to perform two-dimensional ISAR imaging on the function after the window processing to obtain a final spatial domain filter function.

9. An electronic device, comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the method according to any one of claims 1-7 when executing the computer program.

10. A computer readable storage medium, having stored thereon a computer program, which, when executed in a computer, causes the computer to perform the method according to any one of claims 1-7.

Images