Ground testing method, device and equipment for astronomical telescope and medium
By correcting and processing point source array images and dark field image sequences, and combining them with two-dimensional Gaussian fitting, the problem of extracting point spread function under the interference of cosmic rays and electron noise was solved, and efficient and accurate static angular resolution evaluation was achieved.
Patent Information
- Application Number
- CN202511915750.6
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-18
- Publication Date
- 2026-03-17
AI Technical Summary
In ground-based testing, interference factors such as cosmic rays and electron noise introduced during the imaging process make it difficult to accurately and efficiently extract the sub-image blocks containing the spread functions of each point from the point source array image, affecting the reliable assessment of the telescope's static angular resolution.
By correcting the point source array images and dark field image sequences acquired by the detector, removing singular values and performing superposition processing, binarizing the data using standard deviation, performing connected component analysis, screening out effective point spread functions, and combining two-dimensional Gaussian fitting and background subtraction, high-quality point spread function data is extracted.
It achieves accurate and efficient extraction of sub-image blocks containing the spread function of each point from the point source array image, systematically removes interference, and ensures reliable evaluation of the telescope's static angular resolution.
Smart Images
Figure CN121685507A_ABST
Abstract
Description
TECHNICAL FIELD
[0001] The present application relates to the field of ground testing of space optical systems, and in particular to an astronomical telescope ground testing method, device, equipment and medium. BACKGROUND
[0002] Large space optical telescopes are the core equipment for exploring the universe and conducting astronomical research. They are expensive and difficult to maintain in orbit, so performance verification during the ground integration and testing phase is crucial and directly determines the success or failure of the on-orbit mission. Static angular resolution, as a key core indicator of measuring the imaging capability of a telescope, is one of the core contents of ground testing. This test is usually completed by obtaining and analyzing the point spread function (PSF).
[0003] In ground testing, a dot matrix target plate is usually used to generate a point source array. After imaging by the optical system, the point source array forms a point source array image on the focal plane of the detector. The point source array image is essentially a regular arrangement of multiple point spread function instances in space, each of which carries characteristic information of the optical system under test. By calculating the 80% energy concentration angle radius of the point spread function, the static angular resolution of the telescope can be quantitatively evaluated.
[0004] However, in practical applications, cosmic rays, electronic noise and other interference factors are inevitably introduced during the imaging process. These interferences and the signal area formed by the point spread function in the image are mixed together and difficult to distinguish. Therefore, how to accurately and efficiently extract the sub-image block of each point spread function from the point source array image is a technical problem that needs to be solved. SUMMARY
[0005] Therefore, the purpose of the present application is to provide an astronomical telescope ground testing method, device, equipment and medium, which can accurately and efficiently extract the sub-image block of each point spread function from the point source array image, and provide support for reliable evaluation of the static angular resolution of the telescope. The specific scheme is as follows:
[0006] In a first aspect, the present application provides an astronomical telescope ground testing method, comprising:
[0007] correcting a point source array image and a dark field image sequence collected by a detector to obtain a corrected point source array image and a dark field image sequence; the point source array image is an image obtained after imaging a point source array generated by irradiating a dot matrix target plate with a light source, and the dot matrix target plate is a target plate previously arranged on the focal plane of a parallel light tube of an astronomical telescope;
[0008] Superimpose the corrected dark field image sequence, remove singular values in the superimposition process, generate a target dark field image, and determine the standard deviation of the target dark field image;
[0009] Subtract the target dark field image from the corrected point source array image, binarize the image after subtracting the dark field image based on the standard deviation, obtain a first target point source array image, and perform connected domain analysis on the first target point source array image to obtain a first connected domain and a second connected domain; the first connected domain is a connected domain caused by cosmic rays, and the second connected domain is other connected domains in the first target point source array image except the first connected domain;
[0010] Remove the first connected domain from the first target point source array image to obtain a second target point source array image;
[0011] Extract a corresponding image block from the second target point source array image according to the center coordinates of the second connected domain, perform two-dimensional Gaussian fitting on the extracted image block, determine a point spread function based on the two-dimensional Gaussian fitting result, and generate a coordinate array using the center coordinates corresponding to the point spread function;
[0012] Extract a target image block containing a corresponding point source from the second target point source array image with each center coordinate in the coordinate array as the center, and remove the background area in the target image block to complete the ground test of the astronomical telescope using the obtained target point source image block.
[0013] Optionally, the image is corrected to obtain a corrected image, including:
[0014] Determine the data composition of the image collected by the detector; the image collected by the detector includes a point source array image and a dark field image sequence, and the data of the image collected by the detector includes invalid data, pre-scanning data, over-scanning data, and actual photosensitive data; the detector includes a plurality of read channels, each read channel independently collects and outputs image data of a corresponding region, and the image data collected by each read channel is summarized to form a whole frame image;
[0015] According to the data composition, extract the actual photosensitive data from the image collected by the detector as the to-be-corrected valid data;
[0016] For any read channel, determine the over-scanning data mean in the corresponding region of the any read channel, subtract the over-scanning data mean from each pixel value in the to-be-corrected valid data corresponding to the any read channel, and obtain the corrected valid data corresponding to the any read channel;
[0017] Combine the corrected valid data of each read channel to obtain a corrected image.
[0018] Optionally, the superimposed processing is performed on the corrected dark-field image sequence, and singular values are removed in the superimposition process to generate a target dark-field image, including:
[0019] For any position in the image, statistical analysis is performed on the corrected multi-frame dark-field image sequence, and if any pixel value exceeds a preset reasonable pixel value range, the any pixel value is determined as a singular value and removed.
[0020] The remaining normal pixel values of the any position are superimposed to obtain a target dark-field image after superimposition of the multi-frame dark-field image sequence.
[0021] Optionally, the first target point source array image is subjected to connected domain analysis to obtain a first connected domain and a second connected domain, including:
[0022] For any connected domain corresponding to the first target point source array image, a minimum circumscribed rectangle of the any connected domain is determined, a long axis length of the minimum circumscribed rectangle is taken as a long axis, a short axis length of the minimum circumscribed rectangle is taken as a short axis, and a ratio of the long axis to the short axis is calculated.
[0023] If the ratio of the long axis to the short axis exceeds a preset threshold value, the any connected domain is determined as the first connected domain, and if the ratio of the long axis to the short axis does not exceed the preset threshold value, the any connected domain is determined as the second connected domain.
[0024] Correspondingly, the first connected domain is removed from the first target point source array image, including:
[0025] The pixel value corresponding to the first connected domain is set as an invalid value to remove the first connected domain from the first target point source array image.
[0026] Optionally, the corresponding image block is extracted from the second target point source array image according to the center coordinates of the second connected domain, two-dimensional Gaussian fitting is performed on the extracted image block, a point spread function is determined based on the two-dimensional Gaussian fitting result, a coordinate array is generated using the center coordinates corresponding to the point spread function, including:
[0027] The second connected domains are sorted in descending order of connected domain area, the second connected domain with the largest area is taken as a current connected domain, the center coordinates of the current connected domain are determined, and a sub-image block of a preset size is extracted from the second target point source array image with the center coordinates as the center.
[0028] A two-dimensional Gaussian function is fitted to the sub-image block to obtain two fitting standard deviations in mutually perpendicular directions. The two fitting standard deviations are compared with a preset effective range. If both fitting standard deviations are within the preset effective range, the current connected component is determined to constitute an effective point spread function. If neither fitting standard deviation is within the preset effective range, the current connected component is determined not to constitute an effective point spread function.
[0029] Select the next connected component of the current connected component from the second connected components sorted by connected component area from largest to smallest as the new current connected component, and jump to the step of determining the center coordinates of the current connected component, until the number of effective point spread functions selected reaches a preset number threshold.
[0030] A coordinate array is generated based on the center coordinates of the selected valid point spread functions.
[0031] Optionally, the step of extracting target image patches containing corresponding point sources from the second target point source array image, centered on each center coordinate in the coordinate array, includes:
[0032] Using the center coordinates of each point in the coordinate array as the center, extract a square image block with a side length equal to the target side length value from the second target point source array image.
[0033] Optionally, removing the background region from the target image patch includes:
[0034] The target image block is divided into a point source image block located in the central region and a surrounding background region. The average value of all pixel values in the background region is calculated to obtain the background mean.
[0035] Subtract the background mean from each pixel value in the point source image block to obtain the background-corrected target point source image block.
[0036] Secondly, this application provides a ground-based testing device for an astronomical telescope, comprising:
[0037] The image correction module is used to correct the point source array image and dark field image sequence acquired by the detector, respectively, to obtain the corrected point source array image and dark field image sequence; the point source array image is the image obtained after the point source array is imaged by the light source illuminating the point target plate to generate the point source array; the point target plate is a target plate that is pre-set on the focal plane of the collimator of the astronomical telescope.
[0038] The image overlay module is used to overlay the corrected dark field image sequence, remove singular values during the overlay process, generate the target dark field image, and determine the standard deviation of the target dark field image.
[0039] The connected domain analysis module is configured to subtract the target dark field image from the corrected point source array image, binarize the image after the dark field image is subtracted based on the standard deviation, obtain a first target point source array image, and perform connected domain analysis on the first target point source array image to obtain a first connected domain and a second connected domain; the first connected domain is a connected domain caused by cosmic rays, and the second connected domain is other connected domains in the first target point source array image except the first connected domain;
[0040] The connected domain removal module is configured to remove the first connected domain from the first target point source array image to obtain a second target point source array image.
[0041] The function determination module is configured to extract a corresponding image block from the second target point source array image according to the center coordinates of the second connected domain, perform two-dimensional Gaussian fitting on the extracted image block, determine a point spread function based on the two-dimensional Gaussian fitting result, and generate a coordinate array using the center coordinates corresponding to the point spread function.
[0042] The test module is configured to extract a target image block containing a corresponding point source from the second target point source array image with each center coordinate in the coordinate array as the center, remove a background region in the target image block, and complete ground testing of the astronomical telescope using the obtained target point source image block.
[0043] In a third aspect, the present application provides an electronic device, comprising:
[0044] A memory configured to save a computer program.
[0045] A processor configured to execute the computer program to implement the astronomical telescope ground testing method.
[0046] In a fourth aspect, the present application provides a computer readable storage medium configured to save a computer program, wherein the computer program is executed by a processor to implement the astronomical telescope ground testing method.
[0047] In the present application, the point source array image and the dark field image sequence collected by the detector are respectively corrected to obtain the corrected point source array image and the dark field image sequence; the point source array image is an image obtained after a point source array generated by illuminating a point array target plate with a light source, and the point array target plate is a target plate previously arranged on the focal plane of a parallel light tube of an astronomical telescope; the corrected dark field image sequence is subjected to superposition processing, and singular values are removed in the superposition process to generate a target dark field image, and the standard deviation of the target dark field image is determined; the target dark field image is subtracted from the corrected point source array image, the image after the dark field image is subtracted is subjected to binarization processing based on the standard deviation, a first target point source array image is obtained, the first target point source array image is subjected to connected domain analysis to obtain a first connected domain and a second connected domain; the first connected domain is a connected domain caused by cosmic rays, and the second connected domain is other connected domains in the first target point source array image except the first connected domain; the first connected domain is removed from the first target point source array image to obtain a second target point source array image; a corresponding image block is extracted from the second target point source array image according to the center coordinates of the second connected domain, the extracted image block is subjected to two-dimensional Gaussian fitting, a point spread function is determined based on the two-dimensional Gaussian fitting result, and a coordinate array is generated using the center coordinates corresponding to the point spread function; a target image block containing a corresponding point source is extracted from the second target point source array image with each center coordinate in the coordinate array as the center, and a background region in the target image block is removed, so that the ground test of the astronomical telescope is completed using the obtained target point source image block. As can be seen from the above, the present application corrects the point source array image and the dark field image sequence, and superimposes the corrected dark field image sequence, thereby effectively suppressing the influence of the inherent noise of the detector and random singular values. Secondly, the binarization processing and connected domain analysis based on the standard deviation threshold are used to realize the preliminary separation of the signal region, and then the abnormal connected domain caused by cosmic rays is identified and removed. Then, the remaining connected domains are verified and screened by two-dimensional Gaussian fitting, to ensure that the extracted image meets the mathematical characteristics of the point spread function. Finally, through accurate positioning extraction and background subtraction, a pure target point source image block is obtained, which contains the point spread function corresponding to the corresponding point source in the point source array. While retaining all effective point spread functions, the present application systematically removes various interferences, and realizes the automatic and accurate extraction of high-quality point spread function data that can be used for angular resolution evaluation from the point source array image mixed with noise points. BRIEF DESCRIPTION OF DRAWINGS
[0048] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the accompanying drawings needed to be used in the embodiments or prior art description will be briefly introduced as follows. Obviously, the accompanying drawings in the following description only represent some embodiments of the present application, and all other drawings obtained by those of ordinary skill in the art without creative effort based on the accompanying drawings are within the scope of the present application.
[0049] Figure 1 A flow chart of an astronomical telescope ground test method disclosed by the present application;
[0050] Figure 2 A schematic diagram of a specific astronomical telescope ground test method disclosed by the present application;
[0051] Figure 3 A structural schematic diagram of an astronomical telescope ground test device disclosed by the present application;
[0052] Figure 4 A structural schematic diagram of an electronic device disclosed by the present application. DETAILED DESCRIPTION
[0053] The technical solutions in the embodiments of the present application will be described clearly and completely in the following with reference to the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments only represent some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of the present application.
[0054] In actual application, due to the inevitable introduction of cosmic rays, electronic noise and other interference factors in the imaging process, these interferences and the signal area formed by the point spread function in the image are mixed with each other, and it is difficult to distinguish. Therefore, how to accurately and efficiently extract the sub-image block where each point spread function is located from the point source array image is a technical problem to be solved at present. Therefore, the present application provides an astronomical telescope ground test method, which can accurately and efficiently extract the sub-image block where each point spread function is located from the point source array image, and provides support for reliable evaluation of the static angular resolution of the telescope. Referring to Figure 1 As shown in the figure, the embodiment of the present application discloses an astronomical telescope ground test method, which comprises:
[0055] Step S11, correcting the point source array image and the dark field image sequence collected by the detector respectively to obtain the corrected point source array image and the dark field image sequence; the point source array image is an image obtained after a point source array generated by irradiating a point array target plate with a light source is imaged, and the point array target plate is a target plate previously arranged on the focal plane of the parallel light tube of the astronomical telescope.
[0056] In this embodiment, in order to compensate for the detector readout noise and signal offset in the point source array image, the same method can be used to correct the point source array image and the dark field image sequence collected by the detector respectively. Specifically, it can include: determining the data composition of the image collected by the detector; the image collected by the detector includes the point source array image and the dark field image sequence, the data of the image collected by the detector includes invalid data, prescan data (i.e. Prescan data), overscan data (i.e. Overscan data) and actual photosensitive data, the detector includes multiple reading channels, each reading channel independently collects and outputs image data of the corresponding region, and the image data collected by each reading channel is summarized to form a whole frame image; wherein the invalid data is redundant data not used for image processing, the prescan data is reference data used for preheating the circuit before the detector collects the actual image data, the overscan data is reference circuit data collected by the region outside the effective imaging area of the detector, which is not used for recording the actual image and is only used as the reference circuit, and the actual photosensitive data is the image data recorded by the effective imaging area of the detector. Then according to the data composition, the actual photosensitive data collected by the detector is extracted as the to-be-corrected effective data. For any reading channel, the average value of the overscan data in the corresponding region of any reading channel is determined, and each pixel value in the to-be-corrected effective data corresponding to any reading channel is subtracted by the average value of the overscan data, to obtain the corrected effective data corresponding to any reading channel. Finally, the corrected effective data of each reading channel is combined to obtain the corrected image, as shown in Figure 2
[0057] Step S12, superimposing the corrected dark field image sequence, removing the singular values in the superimposition process, generating a target dark field image, and determining the standard deviation of the target dark field image.
[0058] In this embodiment, for any position in the image, statistical analysis can be performed on the corrected multiple dark field image sequence, and if any pixel value exceeds the preset reasonable pixel value range, any pixel value is determined as a singular value and removed. Then the remaining normal pixel values at any position can be superimposed to obtain the target dark field image after superimposition of the multiple dark field image sequence, which is not affected by cosmic rays and unstable singular values.
[0059] Step S13, subtracting the target dark field image from the corrected point source array image, performing binaryzation processing on the image after subtracting the dark field image based on the standard deviation, obtaining a first target point source array image, performing connected domain analysis on the first target point source array image, and obtaining a first connected domain and a second connected domain; the first connected domain is a connected domain caused by cosmic rays, and the second connected domain is other connected domains in the first target point source array image except the first connected domain.
[0060] In this embodiment, as Figure 2 As shown, the target dark field image can first be subtracted from the corrected point source array image. After subtraction, the image after subtracting the dark field image is binarized with a threshold of t times the standard deviation (t can be 5) to obtain the first target point source array image.
[0061] Furthermore, for any connected component corresponding to the first target point source array image, the minimum bounding rectangle of any connected component can be determined. The ratio of the major axis to the minor axis is calculated using the length of the longer side of the minimum bounding rectangle as the major axis and the length of the shorter side as the minor axis. If the ratio exceeds a preset threshold, the connected component is considered to be a connected component caused by cosmic rays and is classified as a first connected component. If the ratio does not exceed the preset threshold, the connected component is classified as a second connected component.
[0062] Step S14: Remove the first connected component from the first target point source array image to obtain the second target point source array image.
[0063] In this embodiment, the pixel values corresponding to the first connected component in the first target point source array image can be set to invalid values to remove the first connected component from the first target point source array image, so that these pixels do not participate in subsequent calculations such as background mean.
[0064] Step S15: Extract corresponding image blocks from the second target point source array image according to the center coordinates of the second connected domain, perform two-dimensional Gaussian fitting on the extracted image blocks, determine the point spread function based on the two-dimensional Gaussian fitting result, and generate a coordinate array using the center coordinates corresponding to the point spread function.
[0065] In this embodiment, the second connected components are first sorted in descending order of area, and the second connected component with the largest area is selected as the current connected component. The center coordinates of the current connected component are determined, and a sub-image patch of a preset size is extracted from the second target point source array image using the center coordinates as the center. Then, a two-dimensional Gaussian function is fitted to the sub-image patch to obtain two fitting standard deviations in mutually perpendicular directions. These two fitting standard deviations are compared with a preset effective range. If both fitting standard deviations are within the preset effective range, the current connected component is determined to constitute a valid point spread function; otherwise, it is determined not to constitute a valid point spread function. Further, the next connected component from the second connected components sorted in descending order of area can be selected as the new current connected component, and the process jumps to the step of determining the center coordinates of the current connected component, until the number of selected valid point spread functions reaches a preset threshold. Finally, a coordinate array can be generated based on the center coordinates of the selected valid point spread functions.
[0066] Understandably, the center coordinates of each connected region are calculated sequentially in descending order of area, and then the points are extracted from the second target point source array image using these coordinates as the center. The image patch is sized and then subjected to 2D Gaussian fitting. Here, N0 can be a small value, such as 10. The standard deviations of the Gaussian function, sigma_x and sigma_y, are obtained through fitting. If at least one of sigma_x and sigma_y is outside the range (0.5 pixels, 1.5 pixels), the current connected component is considered not to constitute a PSF and is excluded. The process continues to filter the next connected component until the number of PSFs meeting the requirements reaches a preset threshold. Simultaneously, the center coordinates corresponding to each PSF are saved. Figure 2 The obtained k sets of center coordinates form a coordinate array.
[0067] Step S16: Using the center coordinates in the coordinate array as the center, extract the target image block containing the corresponding point source from the second target point source array image, and remove the background area in the target image block, so as to complete the ground test of the astronomical telescope using the obtained target point source image block.
[0068] In this embodiment, a square image block with a side length equal to the target side length value can be extracted from the second target point source array image, using the center coordinates of each center in the coordinate array as the center. The target side length value is a side length value determined based on the first number of pixels and the second number of pixels. The spatial angle corresponding to half the number of pixels of the first number is greater than the target spatial angle, which is the spatial angle corresponding to the preset reference radius used to evaluate the energy concentration of the point source. The spatial angle corresponding to half the number of pixels of the second number is less than the target value, which is the difference between the spatial angle corresponding to half the distance between adjacent point sources and the spatial angle corresponding to the reference radius.
[0069] Furthermore, such as Figure 3 As shown, the target image patch can be divided into a point source image patch located in the central region and a surrounding background region. The average value of all pixel values in the background region is calculated to obtain the background mean. Then, the background mean can be subtracted from each pixel value in the point source image patch to obtain the background-corrected target point source image patch, which can be used to complete the ground test of the astronomical telescope.
[0070] From the above, the embodiment corrects a point source array image and a dark field image sequence, superimposes and removes singular values of the dark field image sequence, deducts the dark field image from the corrected point source array image and performs binarization, removes a connected domain caused by cosmic rays, determines a point spread function through target positioning and two-dimensional Gaussian fitting of a dot matrix, extracts a target image block, and removes a background mean value, thereby systematically removing various interferences while retaining all effective point spread functions, accurately and efficiently extracting a sub-image block where each point spread function is located from the point source array image, and providing support for reliable evaluation of a static angular resolution of a telescope.
[0071] Referring to Figure 4 The embodiment of the application further discloses an astronomical telescope ground testing device, which comprises:
[0072] An image correction module 11 is configured to correct a point source array image and a dark field image sequence collected by a detector to obtain a corrected point source array image and a dark field image sequence; the point source array image is an image obtained after imaging of a point source array generated by irradiation of a dot matrix target plate by a light source, and the dot matrix target plate is a target plate previously arranged on a focal plane of a collimator of an astronomical telescope;
[0073] An image superimposition module 12 is configured to superimpose the corrected dark field image sequence and remove singular values in the superimposition process to generate a target dark field image and determine a standard deviation of the target dark field image;
[0074] A connected domain analysis module 13 is configured to deduct the target dark field image from the corrected point source array image, perform binarization processing on the image after deduction of the dark field image based on the standard deviation, obtain a first target point source array image, perform connected domain analysis on the first target point source array image, and obtain a first connected domain and a second connected domain; the first connected domain is a connected domain caused by cosmic rays, and the second connected domain is other connected domains in the first target point source array image except the first connected domain;
[0075] A connected domain removal module 14 is configured to remove the first connected domain from the first target point source array image to obtain a second target point source array image;
[0076] A function determination module 15 is configured to extract a corresponding image block from the second target point source array image according to a center coordinate of the second connected domain, perform two-dimensional Gaussian fitting on the extracted image block, determine a point spread function based on a two-dimensional Gaussian fitting result, and generate a coordinate array by using a center coordinate corresponding to the point spread function;
[0077] The test module 16 is configured to extract a target image block containing a corresponding point source from the second target point source array image, with each center coordinate in the coordinate array as a center, and remove a background region in the target image block, so as to complete ground testing of the astronomical telescope by using the obtained target point source image block.
[0078] In some embodiments, the image correction module 11 comprises:
[0079] A data composition determination unit is configured to determine data composition of an image collected by a detector, wherein the image collected by the detector comprises a point source array image and a dark field image sequence, and data of the image collected by the detector comprises invalid data, pre-scanning data, over-scanning data and actual photosensitive data, and the detector comprises a plurality of reading channels, each reading channel independently collects and outputs image data of a corresponding region, and image data collected by each reading channel is summarized to form a whole frame image.
[0080] A data extraction unit is configured to extract actual photosensitive data as to-be-corrected valid data from the image collected by the detector according to the data composition.
[0081] A data correction unit is configured to determine, for any reading channel, an over-scanning data mean value in a corresponding region of the any reading channel, and subtract the over-scanning data mean value from each pixel value in to-be-corrected valid data corresponding to the any reading channel, to obtain corrected valid data corresponding to the any reading channel.
[0082] A data combination unit is configured to combine the corrected valid data of each reading channel to obtain a corrected image.
[0083] In some embodiments, the image superposition module 12 comprises:
[0084] A pixel value analysis unit is configured to, for any position in an image, statistically analyze a plurality of corrected dark field images in a sequence, and if any pixel value is out of a preset reasonable pixel value range, determine the any pixel value as a singular value and remove the any pixel value.
[0085] A superposition unit is configured to superimpose normal pixel values remaining in the any position to obtain a target dark field image after superposition of the plurality of dark field images in the sequence.
[0086] In some embodiments, the connected domain analysis module 13 comprises:
[0087] A ratio determination unit is configured to, for any connected domain corresponding to the first target point source array image, determine a minimum circumscribed rectangle of the any connected domain, take a long side length of the minimum circumscribed rectangle as a long axis, take a short side length of the minimum circumscribed rectangle as a short axis, and calculate a ratio of the long axis to the short axis.
[0088] The first connected domain determination unit is configured to determine the any connected domain as a first connected domain if the ratio of the major axis to the minor axis exceeds a preset threshold, and determine the any connected domain as a second connected domain if the ratio of the major axis to the minor axis does not exceed the preset threshold.
[0089] Correspondingly, the connected domain removal module 14 comprises:
[0090] The connected domain removal unit is configured to set the pixel value corresponding to the first connected domain as an invalid value, so as to remove the first connected domain from the first target point source array image.
[0091] In some embodiments, the function determination module 15 comprises:
[0092] The first image block extraction unit is configured to sort the second connected domains in descending order of connected domain area, take the second connected domain with the largest area as a current connected domain, determine the center coordinates of the current connected domain, and extract a sub-image block of a preset size from the second target point source array image with the center coordinates as the center;
[0093] The second connected domain determination unit is configured to perform two-dimensional Gaussian function fitting on the sub-image block to obtain fitting standard deviations in two mutually perpendicular directions, compare the two fitting standard deviations with a preset effective range, determine that the current connected domain constitutes an effective point spread function if both fitting standard deviations are within the preset effective range, and determine that the current connected domain does not constitute an effective point spread function if both fitting standard deviations are not within the preset effective range.
[0094] The loop unit is configured to select a next connected domain of the current connected domain as a new current connected domain from the second connected domains sorted in descending order of connected domain area, and jump to the step of determining the center coordinates of the current connected domain, until the number of screened effective point spread functions reaches a preset number threshold.
[0095] The coordinate array generation unit is configured to generate a coordinate array based on the center coordinates of the screened effective point spread functions.
[0096] In some embodiments, the test module 16 comprises:
[0097] The second image block extraction unit is configured to extract a square image block with a target edge length value from the second target point source array image with each center coordinate in the coordinate array as the center.
[0098] In some embodiments, the test module 16 comprises:
[0099] A background mean value determination unit is configured to split the target image block into a point source image block in a central region and a surrounding background region, and calculate a mean value of all pixel values in the background region to obtain a background mean value.
[0100] A background mean value removal unit is configured to subtract the background mean value from each pixel value in the point source image block to obtain a target point source image block after background correction.
[0101] Further, the embodiment of the present application further discloses an electronic device, Figure 4 The electronic device 20 is shown in a structural diagram according to an exemplary embodiment, and the content in the diagram should not be considered as any limitation on the use range of the present application.
[0102] Figure 4 The electronic device 20 is shown in a structural diagram according to an exemplary embodiment, and the content in the diagram should not be considered as any limitation on the use range of the present application.
[0103] In the embodiment, the power supply 23 is configured to provide working voltage for each hardware device on the electronic device 20; the communication interface 24 is capable of creating a data transmission channel between the electronic device 20 and external devices, and the communication protocol followed by the communication interface 24 can be any communication protocol applicable to the technical solution of the present application, which is not limited here; the input and output interface 25 is configured to obtain external input data or output data to the outside, and the specific interface type can be selected according to the specific application needs, which is not limited here.
[0104] In addition, the memory 22 as a carrier for resource storage can be a read-only memory, a random access memory, a magnetic disk or an optical disk, etc., and the resources stored thereon can include an operating system 221, a computer program 222, etc., and the storage mode can be temporary storage or permanent storage.
[0105] The operating system 221 is configured to manage and control each hardware device on the electronic device 20 and the computer program 222, and can be Windows Server, Netware, Unix, Linux, etc. In addition to the computer program capable of completing the astronomical telescope ground test method executed by the electronic device 20 disclosed in any of the foregoing embodiments, the computer program 222 can further include a computer program capable of completing other specific work.
[0106] Further, the application also discloses a computer readable storage medium for storing a computer program, wherein the computer program is executed by a processor to realize the astronomical telescope ground test method disclosed above. For the specific steps of the method, refer to the corresponding content disclosed in the foregoing embodiments, which will not be repeated here.
[0107] The various embodiments are described in the specification by progressive stages, and each embodiment focuses on the differences from other embodiments. For the device disclosed in the embodiments, since it corresponds to the method disclosed in the embodiments, the description is relatively simple, and the relevant parts refer to the method part.
[0108] The skilled person can further realize that the units and algorithm steps of the examples described in combination with the embodiments disclosed herein can be realized by electronic hardware, computer software or a combination of both. In order to clearly illustrate the interchangeability of hardware and software, the components and steps of the examples have been described in the above description in general terms. Whether the functions are realized in hardware or software depends on the specific application and design constraints of the technical solution. The skilled person can use different methods to realize the described functions for each specific application, but such implementation should not be considered beyond the scope of the application.
[0109] The steps of the method or algorithm described in combination with the embodiments disclosed herein can be directly implemented by hardware, a software module executed by a processor, or a combination of both. The software module can be placed in a random access memory (RAM), a memory, a read-only memory (ROM), an electrically programmable ROM, an electrically erasable programmable ROM, a register, a hard disk, a removable disk, a CD-ROM, or any other form of storage medium known in the art.
[0110] Finally, it should be noted that in this document, relational terms such as first and second are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any such actual relationship or order between such entities or actions. Moreover, the terms "comprises", "comprising", or any other variations thereof are intended to cover non-exclusive inclusions, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but can also include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without more limitations, an element defined by the statement "comprising a" does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes the element.
[0111] The technical solutions provided by the present application are described in detail above, and the principles and implementation manners of the present application are described by using specific examples. The above description of the examples is only used to help understand the method of the present application and its core idea; meanwhile, for those skilled in the art, according to the idea of the present application, the specific implementation manners and application ranges will be changed, and the above description of the content of the specification should not be understood as a limitation on the present application.
Claims
1. A method of ground testing an astronomical telescope, characterized by, The method comprises the following steps: The point source array image and the dark field image sequence collected by the detector are respectively corrected to obtain the corrected point source array image and the dark field image sequence; The point source array image is an image obtained by imaging a point source array generated by illuminating a point array target plate by a light source, and the point array target plate is a target plate previously arranged on a focal plane of a parallel light tube of an astronomical telescope; The corrected dark field image sequence is superimposed to remove singular values in the superimposing process, and a target dark field image is generated, and a standard deviation of the target dark field image is determined; The target dark field image is subtracted from the corrected point source array image, the image after the dark field image is subtracted is binarized based on the standard deviation, a first target point source array image is obtained, the first target point source array image is subjected to connected domain analysis, and a first connected domain and a second connected domain are obtained; the first connected domain is a connected domain caused by cosmic rays, and the second connected domain is other connected domains in the first target point source array image except the first connected domain; The first connected domain is removed from the first target point source array image to obtain a second target point source array image; According to the center coordinates of the second connected domain, a corresponding image block is extracted from the second target point source array image, the extracted image block is subjected to two-dimensional Gaussian fitting, a point spread function is determined based on the two-dimensional Gaussian fitting result, and a coordinate array is generated by using the center coordinates corresponding to the point spread function; With each center coordinate in the coordinate array as the center, a target image block containing a corresponding point source is extracted from the second target point source array image, and a background region in the target image block is removed, so that the target point source image block is obtained to complete ground testing of the astronomical telescope.
2. The astronomical telescope ground test method of claim 1, wherein, The image is corrected to obtain a corrected image, comprising: Determine the data composition of the image collected by the detector; the image collected by the detector includes a point source array image and a dark field image sequence, and the data of the image collected by the detector includes invalid data, pre-scanning data, over-scanning data and actual photosensitive data; the detector includes a plurality of reading channels, each reading channel independently collects and outputs image data of a corresponding region, and the image data collected by each reading channel is summarized to form a whole frame image; According to the data composition, the actual photosensitive data is extracted from the image collected by the detector as the to-be-corrected valid data; For any reading channel, the average value of the over-scanning data in the corresponding region of the any reading channel is determined, each pixel value in the to-be-corrected valid data corresponding to the any reading channel is subtracted by the average value of the over-scanning data, and the corrected valid data corresponding to the any reading channel is obtained; The corrected valid data of each reading channel is combined to obtain the corrected image.
3. The astronomical telescope ground test method of claim 1, wherein, The superimposing process of the corrected dark field image sequence removes singular values in the superimposing process to generate a target dark field image, comprising: For any position in the image, statistical analysis is performed on the corrected multiple dark field image sequence, if any pixel value exceeds a preset reasonable pixel value range, the any pixel value is determined as a singular value and removed. Superimpose the normal pixel values remaining in any position to obtain a target dark field image after superimposition of a plurality of dark field image sequences.
4. The astronomical telescope ground test method of claim 1, wherein, The connected domain analysis on the first target point source array image obtains a first connected domain and a second connected domain, and includes: For any connected domain corresponding to the first target point source array image, a minimum circumscribed rectangle of the any connected domain is determined, a long axis is taken as a length of a long side of the minimum circumscribed rectangle, and a short axis is taken as a length of a short side of the minimum circumscribed rectangle, and a ratio of the long axis to the short axis is calculated; If the ratio of the long axis to the short axis exceeds a preset threshold value, the any connected domain is determined as the first connected domain, and if the ratio of the long axis to the short axis does not exceed the preset threshold value, the any connected domain is determined as the second connected domain; Correspondingly, the removing the first connected domain from the first target point source array image includes: A pixel value corresponding to the first connected domain is set as an invalid value to remove the first connected domain from the first target point source array image.
5. The astronomical telescope ground test method of claim 1, wherein, The extracting a corresponding image block from the second target point source array image according to the center coordinates of the second connected domain, the two-dimensional Gaussian fitting on the extracted image block, the determining a point spread function based on a two-dimensional Gaussian fitting result, and the generating a coordinate array by using center coordinates corresponding to the point spread function include: The second connected domains are sorted in a descending order of areas, a second connected domain with a largest area is taken as a current connected domain, and center coordinates of the current connected domain are determined, and a sub-image block with a preset size is extracted from the second target point source array image with the center coordinates as a center. The sub-image block is subjected to two-dimensional Gaussian function fitting to obtain two fitting standard deviations in two mutually perpendicular directions, and the two fitting standard deviations are compared with a preset effective range, if both of the two fitting standard deviations are within the preset effective range, it is determined that the current connected domain constitutes an effective point spread function, and if both of the two fitting standard deviations are not within the preset effective range, it is determined that the current connected domain does not constitute an effective point spread function. A next connected domain of the current connected domain is selected from the second connected domains sorted in the descending order of areas as a new current connected domain, and the step of determining the center coordinates of the current connected domain is jumped to until a number of the screened effective point spread functions reaches a preset number threshold value. A coordinate array is generated based on the center coordinates of the screened effective point spread functions.
6. The astronomical telescope ground test method of claim 1, wherein, The extracting a target image block containing a corresponding point source from the second target point source array image with each center coordinate in the coordinate array as a center includes: A square image block with a target side length value is extracted from the second target point source array image with each center coordinate in the coordinate array as a center.
7. The astronomical telescope ground test method of claim 1, wherein, The removing a background region in the target image block includes: The target image block is split into a point source image block in a central region and a surrounding background region, an average value of all pixel values in the background region is calculated to obtain a background average value, and each pixel value in the point source image block is subtracted by the background average value to obtain a target point source image block after background correction. The method includes:
8. An astronomical telescope ground testing device, characterized by, An image correction module is configured to correct a point source array image and a dark field image sequence acquired by a detector respectively to obtain a corrected point source array image and a dark field image sequence; The point source array image is an image obtained by imaging a point source array generated by illuminating a point array target plate by a light source, and the point array target plate is a target plate previously arranged on a focal plane of a collimator of an astronomical telescope; An image superposition module is configured to superimpose the corrected dark field image sequence, remove singular values in the superposition process, generate a target dark field image, and determine a standard deviation of the target dark field image; A connected domain analysis module is configured to subtract the target dark field image from the corrected point source array image, perform a binaryzation process on the image after the dark field image is subtracted based on the standard deviation, obtain a first target point source array image, perform a connected domain analysis on the first target point source array image, and obtain a first connected domain and a second connected domain; the first connected domain is a connected domain caused by cosmic rays, and the second connected domain is other connected domains in the first target point source array image except the first connected domain; A connected domain removal module is configured to remove the first connected domain from the first target point source array image to obtain a second target point source array image; A function determination module is configured to extract a corresponding image block from the second target point source array image according to a center coordinate of the second connected domain, perform a two-dimensional Gaussian fitting on the extracted image block, determine a point spread function based on a result of the two-dimensional Gaussian fitting, and generate a coordinate array by using a center coordinate corresponding to the point spread function; A test module is configured to extract a target image block containing a corresponding point source from the second target point source array image by taking each center coordinate in the coordinate array as a center, remove a background region in the target image block, and complete ground testing of the astronomical telescope by using the obtained target point source image block.
9. An electronic device, comprising: comprise: a memory configured to save a computer program; a processor configured to execute the computer program to implement the ground testing method of the astronomical telescope according to any one of claims 1 to 7.
10. A computer-readable storage medium, characterized in that, a computer program configured to be executed by a processor to implement the ground testing method of the astronomical telescope according to any one of claims 1 to 7.