Image Smear rapid elimination method and device for satellite load ground detection platform

Abstract

According to the image Smear rapid elimination method and device for the satellite load ground detection platform, after a detection platform receives a data file of an image, a formula (12) is firstly used for calculating a Smear component of each column, operation of a formula (13) is executed, and then a true value of each pixel after Smear elimination can be obtained. Compared with a matrix elimination algorithm, the algorithm of the image Smear rapid elimination method for the satellite load ground detection platform has the advantages that the algorithm is high in operation speed by counting the operation time of a program, and the correction efficiency of the Smear effect can be greatly improved. The algorithm provided by the invention can be directly embedded into control software of a ground inspection station, and compared with a traditional offline Smear elimination algorithm, the algorithm provided by the invention can realize online real-time Smear elimination, so that technicians can conveniently correct optical and electrical parameters of an imaging spectrometer in time.

Description

Technical Field

[0001] The present invention relates to the technical field of image acquisition for a ground detection platform of a hyperspectral imaging spectrometer, and in particular to a method and device for quickly eliminating image smear for a ground detection platform of a satellite payload. Background Art

[0002] The satellite-borne hyperspectral imaging spectrometer obtains the concentration data and geographical distribution of different gas components by collecting spectral images of the earth's atmosphere. The principle structure and observation method of the hyperspectral imaging spectrometer are shown in Figure 1. After the solar reflected light from the ground is incident through the slit, it is focused on the detection focal plane through grating spectroscopy. The area array CCD detector is installed at the focal plane position, and the spectral distribution information is obtained along the row direction of the CCD (spectral dimension), and the geographical distribution information is obtained along the column direction of the CCD (geographic dimension). It can be seen that when the satellite is flying in orbit, the imaging spectrometer is equivalent to using multiple linear array CCDs to simultaneously push and sweep the ground on different spectral lines. The push-sweep process can form a two-dimensional geographical image. Currently, the imaging spectrometer payloads in orbit mostly use 1k 1k area array frame transfer CCD, corresponding to the spectral resolution of 1000 sampling points, the geographical resolution (vertical flight direction) is 1000, and the geographical resolution of the vertical track is determined by the frame rate of the CCD.

[0003] The frame transfer area array CCD is divided into two parts: the imaging area and the storage area. During the exposure time of each image, the imaging area completes charge integration, and the imaging charge is transferred to the storage area through the vertical transfer process (vertical transfer). The storage area then reads out the image line by line. When reading out, one line of the image is first transferred vertically each time, and then horizontally transferred to the output port point by point, and read out by the subsequent circuit. In this way, the frame transfer CCD has the advantages of exposure and reading at the same time without the need for a mechanical shutter. The process of transferring the charge from the imaging area to the storage area is called frame transfer. Because it takes a shorter time to transfer the entire line, it is called frame transfer time. This process also has a short exposure time, which will superimpose additional integration time on the image and in the pixel, which will show a vertical smear effect on the image, affecting the measurement accuracy of the spectrum.

[0004] The CCD device used in my country's first-generation satellite-borne imaging spectrometer has a minimum exposure time of 250ms (frame rate 4 frames / second), and a frame transfer time of 2.5ms. The frame transfer time accounts for a small proportion of the exposure time (no more than 1%), and the Smear effect is not obvious. With the improvement of detector and integrated circuit technology, the second-generation satellite-borne spectrometer uses CCD frame transfer devices with higher speed and deeper wells, with a minimum exposure time of 60ms (frame rate 16 frames / second), and the corresponding frame transfer time is also shortened to 2ms. Although a higher frame rate can achieve a higher signal-to-noise ratio through multiple frame accumulation, the Smear effect becomes more obvious because the frame transfer time accounts for a larger proportion of the entire integration period (maximum 3%). For weak spectral signals, this proportion cannot be ignored.

[0005] After the image data is transmitted to the ground, there will be ground data processing software to eliminate the Smear effect. The existing truncated mean filtering technology, matrix form Smear elimination algorithm and other general algorithms are complex, time-consuming and very long, and belong to offline data processing software. The ground detection platform is used in the development process of the load, and means are provided for the designer to debug and test. Because the Smear effect of the load image is obvious, the subtle spectral data is covered by Smear, so that the real effect can not be seen when the optics and circuits are fine-tuned, and the offline processing data is too cumbersome, and the research and development efficiency is low, and the spectrometer designer needs to see the real image in real time on the detection platform. Therefore, the present invention designs a Smear simplified algorithm suitable for the application of the detection platform.

[0006] In the paper "Research on Spectral Image Data Correction Method of Atmospheric Trace Gas Differential Absorption Spectrometer" published by Zhang Quan of the University of Science and Technology of China, the Smear effect is eliminated through matrix operations (hereinafter referred to as the "matrix elimination algorithm").

[0007] First, assume that the mth row of the CCD photosensitive surface is exposed, and the charge generation rate of each pixel in this row can be considered to be f (t) , the unit is e - / s, then the average charge generation rate of the row during the exposure time is f m It can be expressed as: (1) in, t start and t end Represents the start and end time of exposure, T is the effective exposure time, T = t end - t start .

[0008] After the exposure is completed, the generated signal charge is transferred to the storage area. Assuming that the top row is the first row, the pixels in the first row need to go through n row transfers to reach the storage area, the pixels in the second row need to go through n-1 row transfers to reach, and the last row goes directly into the storage area. Affected by continuous illumination, each row transfer of the first row of pixels will be superimposed with the smear signal generated by the pixels in the previous row during the row transfer time. Similarly, the smear signal generated after the previous frame transfer is also superimposed on the subsequent exposure signal. Since the signal of each pixel is transmitted in the form of a charge packet, it is considered that the smear signal generated after the previous frame transfer is superimposed on the subsequent exposure signal. t / 2( t (row transfer time) during which the charge packet does not enter the next row. t / 2 before entering the next line, the total signal charge number can be expressed as: (2) in F = f × G , G is the gain, which represents the conversion rate between charge and pixel value. F is the pixel value generation rate. It can be seen from the above formula that the charge actually generated by the CCD after exposure is mainly composed of three parts, namely the effective accumulated signal charge generated by the exposure time in the first part, the smear signal charge generated by the previous frame transfer in the second part, and the smear signal charge generated by the current frame transfer in the third part. The smear charge is affected by the generation rate of the current row of pixels at the beginning and end of exposure. Therefore, in order to simplify the impact of the smear effect, it is assumed that the photosensitivity conditions remain unchanged in adjacent imaging frames, that is, the signal charge generation rates are equal at the beginning and end of exposure. , that is , then the above formula is simplified to: (3) In the above formula C The matrix is ​​the obtained pixel value matrix, T is the exposure time, t is the row transfer time, all three are known, let , , , so the actual signal obtained is: C = A × F , at this time, you only need to perform matrix operations on the matrix to get F matrix, and finally compare it with the exposure time T The actual pixel value matrix after smear elimination can be obtained by multiplication. Other smear elimination methods are also in similar matrix form.

[0009] However, the disadvantages of the existing technology are mainly high time complexity, complex calculations, and high consumption of storage space.

[0010] Previous designs used matrices to store data, requiring matrix operations to solve the matrix. Although the method introduced in the Eigen scientific computing library can solve F Matrix, but it is inevitable to perform matrix inversion operations, and the process of matrix inversion is a complicated process, which consumes a lot of time and has complicated calculation process.

[0011] The time to eliminate a frame of smear image using matrix algorithm is 21 seconds. However, the actual working frame rate of the spectrometer is 4 frames per second, and the test bench cannot realize online real-time processing. Therefore, the offline data processing method will make the debugging process extremely complicated. In order to display the spectral image in real time, the processing algorithm must be simplified.

[0012] The present invention mainly solves the problem of quickly eliminating the Smear effect during the image acquisition process of the ground inspection platform of the hyperspectral imaging spectrometer. Specific problems include: 1. The Smear effect is caused by the extra charge generated by the CCD during the frame transfer process. It is superimposed on the charge generated during the actual exposure time of the image, affecting the image measurement accuracy. In the image analysis process, its influence needs to be eliminated. Especially for high-precision spectral imaging equipment, the Smear effect will cover up the fine spectral information.

[0013] 2. The satellite payload ground test station (hereinafter referred to as the "ground test station") is a collection of equipment that provides a test environment for the payload during the satellite payload development stage. For image payload equipment, during the optical assembly and electronics debugging process, the ground test station is required to promptly display the real image after removing the smear, so as to efficiently complete the debugging and testing work.

[0014] 3. The existing smear elimination algorithm is based on matrix description of two-dimensional images, and the algorithm is too complicated. At the image generation speed of the existing project (16 images / second), it cannot achieve real-time processing. A more efficient algorithm for eliminating smear images is needed.

[0015] Terminology explanation: EMI-NI: Environment Monitoring Instrument Nadir and Limb, is a high spectral resolution satellite payload, used for push-scan imaging imaging differential absorption spectrometer payload. CCD275: The image detector carried on EMI-NI is an integrated circuit device of photoelectric conversion technology, composed of an array of photosensitive elements (pixels), which converts images into digital signals. Smear effect: It is a phenomenon that presents a vertical light drag effect on the image. It refers to the accumulation of charge in the pixel during the frame transfer process of CCD imaging, which is superimposed on the charge accumulated during the actual exposure, causing image distortion. When this phenomenon is serious, bright lines will appear along the frame transfer direction of the highlighted pixels. Summary of the invention The present invention provides a method and device for quickly eliminating image smear for a satellite payload ground detection platform, which can at least solve one of the technical problems in the background technology.

[0016] To achieve the above object, the present invention adopts the following technical solutions: A method for quickly eliminating image smear for a satellite payload ground detection platform comprises the following steps: After receiving the image data file, the detection station first uses formula (12) to calculate the smear component of each column, and then subtracts the smear component of the column from each pixel in the entire image file, which is specifically expressed as formula (13): (12) C' (m) Indicates the numerical representation of the smear component. C" (total(m) It is the cumulative sum of the values ​​of all pixels in the m columns of the original data; T trans is the frame transfer time, N Indicates the number of columns of CCD, T int is the exposure time; (13) C (m,n) It represents the value corresponding to the charge accumulated during the exposure of the pixel in the mth column and the nth row. C' (m,n) Indicates the value corresponding to the accumulated charge during the frame transfer period, C" (m,n) Represents the corresponding value of the sum of the integrated charge of the pixel in the mth column and the nth row during the exposure time and the integrated charge during the frame transfer period; Since the value of each pixel is known, and the smear component of each column is calculated by formula (12), the true value of each pixel after eliminating the smear can be obtained by executing the operation of formula (13).

[0017] On the other hand, the present invention further discloses a computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor, the processor executes the steps of the above method.

[0018] On the other hand, the present invention further discloses a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the above method.

[0019] It can be seen from the above technical scheme that, in summary, the algorithm of the image smear fast elimination method used for the satellite payload ground detection platform in the present invention is compared with the matrix elimination algorithm. By statistically analyzing the running time of the program, it can be seen that the algorithm runs fast and can greatly improve the correction efficiency of the smear effect.

[0020] The algorithm in this invention can be directly embedded into the control software of the ground inspection station. Compared with the traditional offline smear elimination algorithm, this algorithm can realize online real-time smear elimination, making it convenient for technicians to correct the optical and electrical parameters of the imaging spectrometer in time.

[0021] This solution is based on the working principle of CCD275, has fast running speed, low time complexity, and can significantly improve the running efficiency of the program. It can meet the ground inspection platform that needs real-time online requirements, ensure real-time and accuracy, and provide timely feedback to the staff to facilitate debugging and correction. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the spectrometer's Earth observation method; Figure 2 It is a schematic diagram of the structure of CCD; Figure 3 This is a schematic diagram of CCD imaging timing; Figure 4 is a graph including the Smear effect; Figure 5 This is the analysis result diagram for eliminating the Smear effect; Figure 6 It is the overall flow chart of the present invention. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0024] First, the CCD imaging principle and the Smear effect principle are as follows: The smear effect occurs during the imaging process of the frame transfer CCD. To understand the mechanism of the smear effect, it is necessary to understand the imaging process of the CCD. The frame transfer CCD is divided into an upper light-sensitive imaging area (Image section) and a lower light-insensitive storage area (Store section). The two are of the same size, and each pixel corresponds one-to-one between the two areas. The CCD used in the project described in this invention is a 1024 CCD from the British E2V company. 1024-pixel frame transfer CCD (model CCD275), such as Figure 2 shown.

[0025] The working principle of continuous frame transfer CCD is generally divided into three steps: exposure, transfer and readout. During exposure, the imaging area receives light signals, and photons are converted into electric charges through the photoelectric effect. After the exposure is completed, the accumulated signal charges are transferred to the storage area in the vertical direction through frame transfer. At this time, the charges in the original storage area are cleared. When the charges in the imaging area are all transferred to the storage area and readout begins, the next frame of the image begins to be exposed. During readout, the image in the storage area is transferred line by line to the readout register for reading out the left and right channels, while the imaging area continues to expose the next frame of the image. This process is repeated continuously to realize the reading of the storage area charges while exposing the imaging area. The circuit timing diagram of this process is shown in the figure. Figure 3 shown.

[0026] During this process, the peripheral imaging circuit mainly performs two operations on the CCD: row transfer (also called vertical transfer) and row readout (also called horizontal transfer). Row transfer refers to moving the CCD charge downward in the vertical direction by one row through the driving timing. Continuously completing 1024 row transfers is called frame transfer, which moves the charge of the entire imaging area to the storage area one by one. After the frame transfer is completed, the pixel readout process begins. This process is to read out the charge in the storage area pixel by pixel. The readout time of this CCD is 60ms, and the frame transfer time is 2ms. Because the frame transfer CCD reads out the storage area while the imaging area is exposed. Therefore, the minimum exposure time is the readout time (62ms). In fact, during the 2ms of frame transfer, the pixels are still continuously exposed (accumulating charges), but they are not aimed at a fixed target but scan the entire field of view, so the bright spots on the image will show the phenomenon of bright lines before and after. For a single image, during the frame transfer process, the bottom row of pixels did not scan the entire exposure focal plane, while the top row (farthest from the storage area) scanned the entire focal plane. However, because the frame transfer CCD is a continuous shooting, the last row of pixels in the frame transfer process of the previous imaging cycle has already scanned a column corresponding to the entire focal plane. In other words, the frame transfer process, for the same column and different rows, is the integration of the corresponding column on the entire focal plane, which is actually a convolution process. Therefore, if the real exposure imaging signal is removed, the 1024 pixels in each column are the convolution of a column of images on the corresponding focal plane. Therefore, the smear effect shows the vertical bright lines above and below the bright spot, such as Figure 4 shown.

[0027] Next, the mathematical analysis and elimination principle of Smear in the embodiment of the present invention are described as follows: When a charge packet enters the storage, its charge quantity is obtained by adding two integration times: exposure time + frame transfer time. Assume that there are n pixels in the imaging area, and the pixel coordinates correspond to 1 from top to bottom. n. The imaging area is located at the focal plane of the optical system, one M When an N-array CCD (M columns, N rows) images the focal plane, it is equivalent to discretizing the image of the focal plane into M N units are sampled. Suppose the number of incident photons per unit time of the pixel in the mth column and nth row is P (m,n) , which is proportional to the light intensity at that point. The charge integrated by the pixel during the exposure time is: (4) In formula (4), Q (m,n) is the charge accumulated during the exposure of the pixel in the nth row of the mth column, K is the photon conversion efficiency of the pixel, T int is the exposure time.

[0028] After the exposure time is completed, the charge packets accumulated under the pixel during the frame transfer time are transferred to the storage area. During the transfer process, the charge is still accumulated. This part of the charge can be expressed as: (5) In formula (5) Q' (m,n) is the charge integrated by the pixel in the mth column and nth row of the imaging surface during the frame transfer period, T rans is the frame transfer time, N Indicates the number of CCD columns.

[0029] As mentioned above, the smear effect is the extra exposure time during the frame transfer process that forms lines along the column direction. It can be considered that the smear effect of each column is independent of each other. In this way, we can only analyze the imaging process of any one column. It can be seen from formula (5) that the smear component of each pixel in each column is the same. Q' (m,n) The value of is only related to m, and has nothing to do with parameter n. That is to say, the smear components of pixels in different rows of the same column are the same. Therefore, it can be deduced that the smear components of each pixel on different columns of the CCD (taking the mth column as an example) can be expressed as: (6) In an original image, the charge number of each pixel is composed of the charge integrated during its exposure time and the charge integrated during the frame transfer process, that is: (7) From formulas (4) and (6), we can get that the total charge of all pixels in each column (taking the mth column as an example) is: (8) From formula (8), we can get: (9) Then, for an image, as long as the pixels in each column are subtracted from the corresponding Q' (m) The image data after Smear is eliminated can be obtained.

[0030] In actual engineering, the image data obtained by the detection station is in numerical form. Each pixel is represented by a 16-bit value. The pixel readout amplifier converts the charge corresponding to the pixel into voltage, and then the analog-to-digital converter of the imaging circuit converts it into digital. The full well charge of the pixel corresponds to 16-bit full "1" (65535). The imaging circuit transmits the digitized image data file to the ground detection station or satellite platform. The value of the pixel in the file is proportional to the pixel charge number. C" indicates that it is proportional to the pixel charge" Q ". Corresponding to the previous formula, C (m,n) It represents the value corresponding to the charge accumulated during the exposure of the pixel in the mth column and the nth row. C' (m,n) Indicates the value corresponding to the accumulated charge during the frame transfer period, C" (m,n) Represents the corresponding value of the sum of the integrated charge of the pixel in the mth column and the nth row during the exposure time and the integrated charge during the frame transfer period.

[0031] The formula for obtaining the smear component is expressed numerically as follows: (10) In the formula K 1 Indicates the ratio of photons converted into numerical values.

[0032] Then the value corresponding to the total charge of each column of pixels (column m) is: (11) From formula (11), we can deduce: (12) The raw data file sent by the spectrometer to the ground inspection station includes the image header and grayscale sequence. The header contains information such as the shooting time, exposure time, track position and chip temperature of the image. T int (Exposure time) is known. The values ​​of all pixels can be obtained according to the grayscale sequence of the image C" (m,n) , the value of each column of pixels in the image (such as the mth column) can be accumulated to obtain C" total(m,n) For a fixed CCD, the frame transfer time is also fixed (2ms), so T trans is also known. N The number of CCD columns is also known. Therefore, the smear component of each column can be calculated according to formula (12).

[0033] Therefore, the process of eliminating Smear is as follows: After receiving the image data file, first use formula (12) to calculate the smear component (value) of each column, and then subtract the smear component of the column from each pixel in the entire image file, which can be specifically expressed as: (13) Since the value of each pixel is known, and the smear component of each column is calculated by formula (12), the true value of each pixel after eliminating the smear can be obtained by executing the operation of formula (13).

[0034] According to the above derivation process, it is called "algebraic elimination algorithm". The images collected by the spaceborne hyperspectral imaging spectrometer are respectively operated using the traditional "matrix elimination algorithm" and "algebraic elimination algorithm" to analyze the elimination of the Smear effect. The final result is as follows Figure 5 As shown in (b) and (c), the two smear removal algorithms have similar visual effects. They can remove the upper and lower bright stripes of the original image and restore the true effect of the image. To further analyze the difference between the two algorithms, the images after using the two removal algorithms are subtracted pixel by pixel. The analysis shows that the values ​​after subtraction are all 0, which means that the two operation methods are completely consistent.

[0035] When the computer configuration is the same as i5-12400F processor, 16GB memory, and Windows 11 operating system, the running speed of the two algorithms is statistically analyzed. The matrix elimination algorithm takes 8s, and the algebraic elimination algorithm takes 16ms. The former takes 500 times as long as the latter. Therefore, it can be concluded that the algebraic form of smear elimination can greatly improve the efficiency of image processing.

[0036] like Figure 6 In the process of eliminating smear at the ground inspection station shown in the figure, smear is eliminated after pressing the smear elimination button. The shortest exposure time of CCD275 used in the current satellite-borne spectrometer is 60ms, while the time consumed for smear elimination using algebraic form is only 16ms. Embedding this algorithm into the control software of the ground inspection station will not affect the overall operation, and the use of an ordinary industrial computer can also ensure real-time online smear elimination.

[0037] In summary, the algorithm in the present invention is compared with the matrix elimination algorithm. By statistically analyzing the running time of the program, it can be seen that the algorithm runs fast and can greatly improve the correction efficiency of the Smear effect.

[0038] The algorithm in this invention can be directly embedded into the control software of the ground inspection station. Compared with the traditional offline smear elimination algorithm, this algorithm can realize online real-time smear elimination, making it convenient for technicians to correct the optical and electrical parameters of the imaging spectrometer in time.

[0039] This solution is based on the working principle of CCD275, has fast running speed, low time complexity, and can significantly improve the running efficiency of the program. It can meet the ground inspection platform that needs real-time online requirements, ensure real-time and accuracy, and provide timely feedback to the staff to facilitate debugging and correction.

[0040] On the other hand, the present invention further discloses a computer-readable storage medium storing a computer program, wherein when the computer program is executed by a processor, the processor executes the steps of the above method.

[0041] On the other hand, the present invention further discloses a computer device, including a memory and a processor, wherein the memory stores a computer program, and when the computer program is executed by the processor, the processor executes the steps of the above method.

[0042] In another embodiment provided in the present application, a computer program product comprising instructions is also provided, which, when executed on a computer, enables the computer to execute any of the above-mentioned methods for rapid image smear elimination for a satellite-borne ground detection platform.

[0043] It is understandable that the system, device and storage medium provided in the embodiments of the present invention correspond to the method provided in the embodiments of the present invention, and the explanation, examples and beneficial effects of the relevant contents can refer to the corresponding parts in the above methods.

[0044] In the above embodiments, it can be implemented in whole or in part by software, hardware, firmware or any combination thereof. When implemented using software, it can be implemented in whole or in part in the form of a computer program product. The computer program product includes one or more computer instructions. When the computer program instructions are loaded and executed on a computer, the process or function described in the embodiment of the present application is generated in whole or in part. The computer may be a general-purpose computer, a special-purpose computer, a computer network, or other programmable device. The computer instructions may be stored in a computer-readable storage medium, or transmitted from one computer-readable storage medium to another computer-readable storage medium. For example, the computer instructions may be transmitted from a website site, a computer, a server or a data center by wired (e.g., coaxial cable, optical fiber, digital subscriber line (DSL)) or wireless (e.g., infrared, wireless, microwave, etc.) mode to another website site, computer, server or data center. The computer-readable storage medium may be any available medium that a computer can access or a data storage device such as a server or a data center that includes one or more available media integrated. The available medium may be a magnetic medium (e.g., a floppy disk, a hard disk, a tape), an optical medium (e.g., a DVD), or a semiconductor medium (e.g., a solid-state drive Solid State Disk (SSD)), etc.

[0045] It should be noted that, in the present invention, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device. In the absence of further restrictions, the elements defined by the sentence "comprise a ..." do not exclude the existence of other identical elements in the process, method, article or device including the elements.

[0046] Each embodiment in this specification is described in a related manner, and the same or similar parts between the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the relevant parts can be referred to the partial description of the method embodiment.

[0047] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for quickly eliminating image smear for a satellite payload ground detection platform, characterized in that: After receiving the image data file, the detection station first uses formula (12) to calculate the smear component of each column, and then subtracts the smear component of the column from each pixel in the entire image file, which is specifically expressed as formula (13): (12) C' (m) Indicates the numerical representation of the smear component. C" total(m) It is the cumulative sum of the values ​​of all pixels in the m columns of the original data; T trans is the frame transfer time, N Indicates the number of columns of CCD, T int is the exposure time; （13） C (m,n) It represents the value corresponding to the charge accumulated during the exposure of the pixel in the mth column and the nth row. C' (m,n) Indicates the value corresponding to the accumulated charge during the frame transfer period, C" (m,n) Represents the corresponding value of the sum of the integrated charge of the pixel in the mth column and the nth row during the exposure time and the integrated charge during the frame transfer period; Since the value of each pixel is known, and the smear component of each column is calculated by formula (12), the true value of each pixel after eliminating the smear can be obtained by executing the operation of formula (13).

2. A computer device comprising a memory and a processor, wherein the memory stores a computer program, characterized in that: When the computer program is executed by the processor, the processor is caused to perform the steps of the method according to claim 1 .

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