Calibration method and device of radiation correction lookup table, electronic equipment and storage medium

Abstract

The invention provides a calibration method and device of a radiation correction lookup table, electronic equipment and a storage medium. The method comprises the steps that an initial radiation correction lookup table is generated for each probe element; correcting each obtained uniform ground feature image by using the initial radiation correction lookup table to obtain a plurality of preliminarily corrected images; determining an original gray average value corresponding to each probe element from the uniform ground feature image, and determining a total image gray average value from the preliminary correction image; for each probe element, calculating an offset according to the original gray average value, the total image gray average value and the initial radiation correction lookup table of the probe element; and based on the offset corresponding to each original gray average value corresponding to the probe element, moving the corrected gray value corresponding to the original pixel gray value which is the same as the original gray average value in the initial radiation correction lookup table so as to establish a new mapping relation and obtain a calibrated radiation correction lookup table. Through the method, the accuracy of the radiation correction lookup table is improved.

Description

Technical Field

[0001] This application relates to the field of remote sensing image processing technology, and in particular to a calibration method, apparatus, electronic device and storage medium for a radiometric correction lookup table. Background Technology

[0002] A sensor element refers to the individual detection units contained in the camera sensor on a satellite. Remote sensing images typically refer to images of the ground taken by these sensors on a satellite, stitched together to form a complete image. Due to manufacturing differences and wear and tear, different sensors may have slightly different sensitivities to light, resulting in subtle differences in color and brightness in the images they capture. For example, when photographing the same scene, some sensors may produce images that are slightly brighter than others. When these images are stitched together into a large image, they will form vertical stripes of inconsistent color or brightness.

[0003] Therefore, after obtaining remote sensing images, it is usually necessary to perform relative radiometric calibration on the remote sensing images. The purpose is to unify the DN values ​​(i.e., gray values) of images taken by different detectors, so that the DN values ​​(i.e., gray values) of different pixels in the remote sensing images after relative radiometric calibration tend to be consistent, thereby solving the problem of slight differences in color and brightness in images taken by different detectors.

[0004] When performing relative radiometric calibration on remote sensing images, the core task is to establish an accurate radiometric correction lookup table for each detector element. This radiometric correction lookup table contains the mapping relationship between the original pixel grayscale value and the corrected grayscale value.

[0005] Currently, traditional methods for establishing radiometric correction lookup tables typically rely on observations of a single homogeneous ground feature scene. Specifically, this method first acquires a single remote sensing image of the same homogeneous ground feature (such as a large desert or a calm, deep-water area) taken by various detectors on a satellite; then, based on this single remote sensing image, it calculates a radiometric correction lookup table for each detector.

[0006] If the remote sensing image itself has lighting issues, or if a particular detector failed to capture the image properly, the resulting radiometric correction lookup table will be inaccurate. Using this inaccurate lookup table to perform relative radiometric calibration on subsequently acquired remote sensing images will negatively impact the visual quality of the calibrated images. Summary of the Invention

[0007] In view of this, the purpose of this application is to provide a calibration method, apparatus, electronic device and storage medium for a radiation correction lookup table, so as to improve the accuracy of the radiation correction lookup table.

[0008] In a first aspect, embodiments of this application provide a calibration method for a radiation correction lookup table, including: The system acquires images of the target ground feature taken by the satellite through various detectors on the satellite in a yaw attitude. Based on the target ground feature images, an initial radiometric correction lookup table is generated for each detector. The initial radiometric correction lookup table includes the mapping relationship between the original pixel grayscale value and the corrected grayscale value of the detector. Multiple images of uniform ground features taken by various detectors on the satellite are acquired. Each image of uniform ground features is then corrected using the initial radiometric correction lookup table to obtain multiple corresponding preliminary corrected images. For each uniform ground feature image and its corresponding preliminary correction image, an original grayscale mean value corresponding to each detector element is determined from the uniform ground feature image, and the grayscale mean value of the entire image is determined from the preliminary correction image. For each of the probe elements, an offset corresponding to the original gray-scale mean is calculated based on the original gray-scale mean of the probe element, the gray-scale mean of the entire image, and the initial radiometric correction lookup table of the probe element; wherein, each of the probe elements corresponds to the offset of the original gray-scale mean determined from multiple uniform ground feature images of different sizes. For each detector element, based on the offset corresponding to each of the original grayscale average values ​​corresponding to the detector element, the correction grayscale value corresponding to the original pixel grayscale value that is the same as the original grayscale average value in the initial radiometric correction lookup table of the detector element is moved to establish a new mapping relationship, thereby obtaining the calibrated radiometric correction lookup table corresponding to the detector element.

[0009] In conjunction with the first aspect, this application provides a first possible implementation of the first aspect, wherein acquiring target ground feature images of the same ground feature taken by the satellite through various detectors on the satellite in a yaw attitude, and generating an initial radiometric correction lookup table for each detector based on the target ground feature images, includes: The target image is obtained when a row of sensors on the satellite takes pictures of the same ground feature sequentially as the satellite moves while the satellite is in a yaw attitude. The target feature image is flattened so that each row of pixels in the target feature image corresponds to the same feature on the ground; each column of pixels in the target feature image corresponds to one detector element. For each column of pixels in the target feature image, calculate the first gray-level histogram of the corresponding probe element, and calculate the first cumulative probability density function of the probe element based on the first gray-level histogram. Based on all pixels of the entire target ground image, calculate its corresponding second gray-level histogram, and calculate the overall cumulative probability density function based on the second gray-level histogram; For each detector element, based on the first cumulative probability density function and the overall cumulative probability density function of the detector element, the corrected gray value to which each original pixel gray value of the detector element should be mapped is determined, so as to generate the initial radiometric correction lookup table of the detector element.

[0010] In conjunction with the first aspect, this application provides a second possible implementation of the first aspect, wherein, after generating an initial radiometric correction lookup table for each of the detectors based on the target feature image, the method further includes: Acquire first images taken by each probe on the satellite; For each pixel in the first image, determine the image column in which the pixel is located, and determine the corresponding first target detector based on the image column; Using the original pixel grayscale value of the pixel as input, the initial radiometric correction lookup table corresponding to the first target detector is queried. If the mapped corrected grayscale value is found, the pixel is taken as the first pixel; if the mapped corrected grayscale value is not found, the pixel is taken as the second pixel. For each second pixel in the first image, determine the two first pixels in the first image that are closest to the second pixel in the vertical or horizontal direction and are located on both sides of the first pixel. Based on the corrected gray values ​​retrieved for each of the two first pixels, interpolate the corrected gray value of the second pixel. Use the result of the interpolation calculation as the corrected gray value of the original pixel gray value of the second pixel and add it to the initial radiometric correction lookup table corresponding to the first target probe.

[0011] In conjunction with the first aspect, this application provides a third possible implementation of the first aspect, wherein acquiring multiple uniform ground feature images taken by each of the detectors on the satellite, and correcting each uniform ground feature image using the initial radiometric correction lookup table to obtain multiple corresponding preliminary corrected images, includes: Acquire multiple original images of a uniform ground feature taken by various detectors on the satellite of at least one uniform ground feature; For each pixel in each original image of the uniform ground features, determine the image column in which the pixel is located, and determine the corresponding second target element based on the image column. Using the original pixel grayscale value of the pixel as input, the initial radiometric correction lookup table corresponding to the second target detector is queried to obtain the mapped corrected grayscale value; Replace the grayscale value of the pixel in the original image of the uniform ground features with the queried corrected grayscale value; After traversing and processing all pixels in the original image of uniform features, a preliminary corrected image of the original image of uniform features is generated.

[0012] In conjunction with the first aspect, this application provides a fourth possible implementation of the first aspect, wherein, for each uniform ground feature image and its corresponding preliminary correction image, determining an original grayscale mean value corresponding to each detector element from the uniform ground feature image, and determining the overall grayscale mean value from the preliminary correction image, includes: For each uniform ground feature image, the average gray value of the multiple columns of pixels corresponding to each probe element in the uniform ground feature image is calculated as the original average gray value of the probe element. Calculate the average grayscale value of the entire image of the preliminary corrected image corresponding to the uniform ground feature image.

[0013] In conjunction with the fourth possible implementation of the first aspect, this application provides a fifth possible implementation of the first aspect, wherein, for each of the detector elements, calculating an offset corresponding to the original gray-scale mean based on the original gray-scale mean of the detector element, the overall gray-scale mean, and the initial radiometric correction lookup table of the detector element includes: For each of the detector elements, with the average grayscale value of the entire image as the target output value, the initial radiometric correction lookup table for that detector element is looked up in reverse to obtain the expected input value required for the output of the initial radiometric correction lookup table to reach the target output value. The difference between the expected input value and the original grayscale mean is calculated as an offset of the probe corresponding to the original grayscale mean, so as to obtain the offset of the probe corresponding to each original grayscale mean based on the original grayscale mean of each uniform ground object image.

[0014] In conjunction with the first aspect, this application provides a sixth possible implementation of the first aspect, wherein, for each of the detector elements, based on the offset corresponding to each of the original grayscale average values ​​corresponding to that detector element, the corrected grayscale value corresponding to the original pixel grayscale value with the same original grayscale average value in the initial radiometric correction lookup table of that detector element is shifted to establish a new mapping relationship, thereby obtaining the calibrated radiometric correction lookup table corresponding to that detector element, including: For each detector element, the gray values ​​of each original pixel that have the same mean original gray value as the detector element are determined from the initial radiometric correction lookup table corresponding to the detector element, and are used as the target original pixel gray values. For each target original pixel grayscale value, add its corresponding offset to the target original pixel grayscale value to obtain the offset original pixel grayscale value; Using the original pixel grayscale value of the target as input, the initial radiometric correction lookup table of the probe is queried to obtain the target corrected grayscale value; The target corrected gray value in the initial radiometric correction lookup table is moved to the corrected gray value corresponding to the original pixel gray value after the offset, so as to establish a new mapping relationship between the original pixel gray value after the offset and the target corrected gray value, thereby forming the calibrated radiometric correction lookup table corresponding to the detector.

[0015] In conjunction with the sixth possible implementation of the first aspect, this application provides a seventh possible implementation of the first aspect, wherein, after obtaining the calibrated radiation correction lookup table corresponding to the detector, the method further includes: Traverse the calibrated radiometric correction lookup table corresponding to the detector, find the original pixel gray value that has not established a new mapping relationship, and use it as the original pixel gray value to be interpolated. For each original pixel gray value to be interpolated, in the calibrated radiometric correction lookup table, search along the positive and negative directions of the original pixel gray value axis for the previous and next original pixel gray values ​​that are closest to it and have established a new mapping relationship, and obtain their corresponding target correction gray values. Based on the previous original pixel gray value, the next original pixel gray value, and its corresponding target correction gray value, linear interpolation is performed on the target correction gray value missing from the original pixel gray value to be interpolated. The calculated interpolation result is used as the target corrected gray value mapped to the original pixel gray value to be interpolated, and is added to the calibrated radiometric correction lookup table to form a complete radiometric correction lookup table.

[0016] Secondly, embodiments of this application also provide a calibration apparatus for a radiation correction lookup table, comprising: The first acquisition module is used to acquire target ground object images taken by the satellite through various detectors on the satellite in a yaw attitude, and to generate an initial radiometric correction lookup table for each detector based on the target ground object images; the initial radiometric correction lookup table includes the mapping relationship between the original pixel grayscale value and the corrected grayscale value of the detector. The second acquisition module is used to acquire multiple uniform ground object images taken by each of the probes on the satellite, and to correct each uniform ground object image using the initial radiometric correction lookup table to obtain multiple corresponding preliminary corrected images. The first determining module is used to determine, for each uniform ground feature image and its corresponding preliminary correction image, an original grayscale mean value corresponding to each probe element from the uniform ground feature image, and to determine the grayscale mean value of the entire image from the preliminary correction image; The calculation module is used to calculate, for each of the probe elements, an offset corresponding to the original gray-scale mean of the probe element, based on the original gray-scale mean of the probe element, the gray-scale mean of the entire image, and the initial radiometric correction lookup table of the probe element; wherein, each of the probe elements corresponds to an offset corresponding to the original gray-scale mean determined from multiple uniform ground feature images of different sizes. The calibration module is used to, for each of the detector elements, based on the offset corresponding to each of the original grayscale average values ​​corresponding to the detector element, move the correction grayscale value corresponding to the original pixel grayscale value that is the same as the original grayscale average value in the initial radiometric correction lookup table of the detector element, so as to establish a new mapping relationship and obtain the calibrated radiometric correction lookup table corresponding to the detector element.

[0017] Thirdly, embodiments of this application also provide an electronic device, including: a processor, a memory, and a bus, wherein the memory stores machine-readable instructions executable by the processor, and when the electronic device is running, the processor communicates with the memory via the bus, and when the machine-readable instructions are executed by the processor, the steps in any of the possible implementations of the first aspect described above are performed.

[0018] Fourthly, embodiments of this application also provide a computer-readable storage medium storing a computer program that, when executed by a processor, performs the steps in any of the possible implementations of the first aspect described above.

[0019] This application provides a calibration method, apparatus, electronic device, and storage medium for a radiometric correction lookup table. After generating an initial radiometric correction lookup table, multiple images of uniform ground features taken by various detectors on a satellite are acquired. The initial radiometric correction lookup table is used to correct each uniform ground feature image, resulting in multiple corresponding preliminary corrected images. Then, for each uniform ground feature image and its corresponding preliminary corrected image, an original grayscale mean value corresponding to each detector is determined from the uniform ground feature image, and the overall grayscale mean value is determined from the preliminary corrected image. Furthermore, for each detector, based on its original grayscale mean value, the overall grayscale mean value, and the initial radiometric correction lookup table, an offset corresponding to the original grayscale mean value is calculated. This allows each detector to obtain offsets corresponding to the original grayscale mean values ​​determined from multiple different uniform ground feature images. This results in each detector obtaining multiple offsets associated with its different original grayscale mean values. These offsets characterize the mapping deviation of the detector's initial radiometric correction lookup table under different brightness conditions in practical applications. Finally, for each detector element, based on the offset corresponding to each original grayscale mean value, the corrected grayscale values ​​corresponding to the original pixel grayscale values ​​with the same original grayscale mean value in the initial radiometric correction lookup table for that detector element are shifted to establish a new mapping relationship, thereby obtaining the calibrated radiometric correction lookup table corresponding to that detector element. This embodiment, by calibrating the initial radiometric correction lookup table, enables the generated calibrated radiometric correction lookup table to more comprehensively and accurately reflect and compensate for the response differences of each detector element, thus improving the accuracy of the radiometric correction lookup table.

[0020] To make the above-mentioned objectives, features and advantages of this application more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0021] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0022] Figure 1 A flowchart illustrating a calibration method for a radiation correction lookup table provided in an embodiment of this application is shown; Figure 2 This illustration shows a schematic diagram of a satellite photographing ground features in normal attitude, provided by an embodiment of this application. Figure 3This illustration shows a schematic diagram of a satellite taking a picture of the same ground feature in a yaw attitude, according to an embodiment of this application. Figure 4 This illustration shows a schematic diagram of a target feature image provided in an embodiment of this application; Figure 5 This illustration shows a target feature image after flattening, as provided in an embodiment of this application. Figure 6 This illustration shows a schematic diagram of a uniform ground feature image and its corresponding preliminary correction image provided by an embodiment of this application; Figure 7 A schematic diagram of an initial radiation correction lookup table corresponding to detector T1 provided in an embodiment of this application is shown; Figure 8 This illustration shows a schematic diagram of calibrating an initial radiation correction lookup table according to an embodiment of this application; Figure 9 This illustration shows a schematic diagram of the structure of a calibration device for a radiation correction lookup table provided in an embodiment of this application; Figure 10 A schematic diagram of the structure of an electronic device provided in an embodiment of this application is shown. Detailed Implementation

[0023] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely represents selected embodiments of this application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0024] Considering that traditional methods for creating radiation correction lookup tables often result in inaccuracies, this application provides a calibration method, apparatus, electronic device, and storage medium for radiation correction lookup tables to improve their accuracy. These embodiments are described below.

[0025] To facilitate understanding of this embodiment, a calibration method for a radiation correction lookup table disclosed in this application will first be described in detail. For example... Figure 1 As shown, the process includes the following steps S101-S105: S101: Acquire target ground object images taken by the satellite through various detectors on the satellite in yaw attitude, and generate an initial radiometric correction lookup table for each detector based on the target ground object images; the initial radiometric correction lookup table includes the mapping relationship between the original pixel grayscale value and the corrected grayscale value of the detector.

[0026] In this embodiment, each detector element on the satellite refers to the individual detection units within the camera sensors on the satellite. Typically, the detector elements on the satellite are arranged in a single line.

[0027] In one possible implementation, when performing step S101, the following steps S1011-S1015 can be specifically performed: S1011: Obtain images of the target ground features when the satellite is in a yaw attitude and a row of sensors on the satellite sequentially photograph the same ground feature as the satellite moves.

[0028] In this embodiment, under normal satellite attitude, a row of sensors (multiple sensors arranged in a line, such as 6000 sensors from left to right) simultaneously observe different points on the ground (e.g., 6000 points). For example,... Figure 2 As shown, the explanation is based on six detectors (T1-T6). Detector T1 observes region 1 on the ground; detector T2 observes region 2 on the ground; detector T3 observes region 3 on the ground, and so on.

[0029] When a satellite is in a yaw attitude, a row of sensors on the satellite will sequentially scan the same ground feature as the satellite flies. For example, such as... Figure 3 As shown, probes T1-T6, as the satellite flies (i.e., moves), will sequentially scan the same ground feature in the same area. There can be multiple ground features. Figure 3 The image shows three ground features. In this example, probes T1-T6 will sequentially scan the same ground feature 1, the same ground feature 2, and the same ground feature 3 in the same area on the ground.

[0030] At this time, as Figure 4 As shown, in the target feature image obtained when a row of detectors (such as T1-T6) on a satellite sequentially photographs the same ground feature (such as feature 1-3) as the satellite moves, each column of pixels corresponds to an image taken by one detector of each feature (feature 1-3) in sequence. In the target feature image, when different detectors photograph the same feature, because the shooting times are different (in this example, detector T1 photographs feature 1 first, and detector T6 photographs feature 1 last), the images of the same feature taken by different detectors are arranged diagonally in the target feature image.

[0031] S1012: Flatten the target feature image so that each row of pixels in the target feature image corresponds to the same feature on the ground; each column of pixels in the target feature image corresponds to one detector element.

[0032] In this embodiment, considering that the pixel values ​​of overexposed and underexposed areas in the target ground object image are distorted and cannot represent the true response characteristics of the sensor, using distorted pixel values ​​to statistically analyze the brightness distribution (histogram) would introduce serious errors. Therefore, it is necessary to first remove areas in the target ground object image with brightness values ​​greater than the upper limit of the brightness threshold, and areas with brightness values ​​less than the lower limit of the brightness threshold; where the upper limit of the brightness threshold is the maximum brightness value of the image captured by the probe, and the lower limit of the brightness threshold is the minimum brightness value of the image captured by the probe.

[0033] Then, the target feature image is flattened, such as... Figure 5 As shown, this is done so that each row of pixels in the target feature image corresponds to the same feature on the ground, and each column of pixels in the target feature image corresponds to a probe element.

[0034] S1013: For each column of pixels in the target ground object image, calculate the first gray-level histogram of the corresponding probe element, and calculate the first cumulative probability density function of the probe element based on the first gray-level histogram.

[0035] In this embodiment, a first grayscale histogram is calculated based on the columns of pixels corresponding to each probe element in the target feature image. The first grayscale histogram represents the frequency of occurrence of each grayscale value in each column of pixels corresponding to that probe element, that is, the ratio of the number of times each grayscale value appears to the total number of times all grayscale values ​​appear. Each probe element corresponds to one first grayscale histogram.

[0036] Based on the first gray-level histogram corresponding to each probe element, the first cumulative probability density function corresponding to that probe element is calculated, and each probe element corresponds to a first cumulative probability density function.

[0037] The first cumulative probability density function represents the cumulative frequency of occurrence of gray values ​​in each column of pixels corresponding to the probe, from smallest to largest. For example, when calculating the first cumulative probability density function, first count how many times the gray value 0 appears, and divide by the total number of times all gray values ​​appear; then count how many times gray values ​​0 and 1 appear together, and divide by the total number of times all gray values ​​appear; then count how many times gray values ​​0, 1, and 2 appear together, and divide by the total number of times all gray values ​​appear, and so on.

[0038] S1014: Based on all pixels of the entire target ground object image, calculate the corresponding second gray-level histogram, and calculate the overall cumulative probability density function based on the second gray-level histogram.

[0039] In this embodiment, a second grayscale histogram of the entire target feature image is calculated based on the flattened image of the entire target feature image.

[0040] The second cumulative histogram represents the frequency of grayscale values ​​in the entire target image. The overall cumulative probability density function represents the cumulative frequency of grayscale values ​​in the entire target image, from smallest to largest.

[0041] S1015: For each detector element, based on the first cumulative probability density function and the overall cumulative probability density function of the detector element, determine the corrected gray value to which each original pixel gray value of the detector element should be mapped, so as to generate the initial radiometric correction lookup table for the detector element.

[0042] In this embodiment, for each detector element, an initial radiometric correction lookup table is generated based on the detector element's first cumulative probability density function and the overall cumulative probability density function of the entire target ground image. The initial radiometric correction lookup table includes a one-to-one mapping relationship between the detector element's original pixel grayscale values ​​and corrected grayscale values.

[0043] In one possible implementation, the initial radiometric correction lookup table may contain original pixel grayscale values ​​without a mapping relationship (i.e., original pixel grayscale values ​​without mapped correction values), for example, the original pixel grayscale value 119 has no mapping. For original pixel grayscale values ​​without mapped correction values ​​in the initial radiometric correction lookup table, they need to be supplemented with values ​​in the initial radiometric correction lookup table. Therefore, after performing step S101 to generate an initial radiometric correction lookup table for each detector based on the target ground object image, the original pixel grayscale values ​​without mapped correction values ​​in the initial radiometric correction lookup table can also be supplemented with values ​​according to the following steps S201-S204: S201: Acquire the first images taken by each probe on the satellite.

[0044] In this embodiment, the first image is a remote sensing image taken by the satellite in its normal attitude.

[0045] S202: For each pixel in the first image, determine the image column in which the pixel is located, and determine the corresponding first target probe based on the image column.

[0046] In this embodiment, referring to the aforementioned step S1011, each image column in the first image corresponds to one probe.

[0047] S203: Using the original pixel grayscale value of the pixel as input, query the initial radiometric correction lookup table corresponding to the first target detector. If the mapped correction grayscale value is found, then the pixel is used as the first pixel; if the mapped correction grayscale value is not found, then the pixel is used as the second pixel.

[0048] In this embodiment, if the corrected gray value mapped to the original pixel gray value of the pixel is found in the initial radiometric correction lookup table corresponding to the first target detector, it indicates that there is a mapping relationship between the original pixel gray value of the pixel in the initial radiometric correction lookup table. At this time, the pixel of this type is taken as the first pixel, and the gray value of the pixel (first pixel) in the first image is replaced with the found corrected gray value.

[0049] If the corrected gray value mapped to the original pixel gray value of the pixel is not found in the initial radiometric correction lookup table corresponding to the first target detector, it indicates that the original pixel gray value of the pixel in the initial radiometric correction lookup table is the original pixel gray value with a missing mapping relationship, and this type of pixel is regarded as the second pixel.

[0050] S204: For each second pixel in the first image, determine the two first pixels in the first image that are closest to the second pixel in the vertical or horizontal direction and are located on both sides of the first pixel. Based on the corrected gray value corresponding to each of the two first pixels, perform interpolation calculation on the corrected gray value of the second pixel. Use the result of the interpolation calculation as the corrected gray value of the original pixel gray value of the second pixel and add it to the initial radiometric correction lookup table corresponding to the first target detector.

[0051] In this embodiment, the vertical and horizontal directions are relative to the first image.

[0052] For example, suppose that in the initial radiometric correction lookup table, the original pixel gray value 119 has no mapped correction gray value, the original pixel gray value 118 has a correction gray value of x0, and the original pixel gray value 120 has a correction gray value of x1.

[0053] After correcting the first image using the initial radiometric correction lookup table through steps S201-S203 to obtain the corrected image, for example, when the corrected image contains three consecutive pixels, the first pixel has an original pixel gray value of 120 and a mapped corrected gray value of x1, belonging to the first pixel; the second pixel has an original pixel gray value of 119 and no mapping relationship, belonging to the second pixel; the third pixel has an original pixel gray value of 118 and a mapped corrected gray value of x0. At this point, interpolation can be performed on x0 and x1. The result of the interpolation is used as the corrected gray value of the original pixel gray value of the second pixel, and it is added to the initial radiometric correction lookup table corresponding to the first target element to obtain the completed initial radiometric correction lookup table.

[0054] After obtaining the initial radiometric correction lookup table after the compensation is completed, the subsequent step S102 uses the initial radiometric correction lookup table after the compensation is completed to correct each uniform ground feature image.

[0055] S102: Acquire multiple images of uniform ground features taken by various probes on the satellite, and use the initial radiometric correction lookup table to correct each uniform ground feature image to obtain multiple corresponding preliminary corrected images.

[0056] In this embodiment, a uniform ground feature refers to a large, uniform, and stable area on the ground, such as a desert or the sea surface. There can be one or more uniform ground features. That is, multiple images of a uniform ground feature can be multiple remote sensing images obtained by various sensors on a satellite taking multiple pictures of the same uniform ground feature; or multiple images can be obtained by various sensors on a satellite taking a single picture of the same uniform ground feature, then segmenting that picture; or multiple remote sensing images can be obtained by various sensors on a satellite taking pictures of different uniform ground features.

[0057] In one possible implementation, when performing step S102, the following steps S1021-S1025 can be specifically performed: S1021: Acquire multiple original images of a uniform ground feature taken by various probes on the satellite at least one uniform ground feature.

[0058] In this embodiment, the original image of uniform ground features is a remote sensing image taken by a satellite in its normal attitude.

[0059] S1022: For each pixel in each original image of uniform ground features, determine the image column in which the pixel is located, and determine the corresponding second target element based on the image column.

[0060] In this embodiment, referring to the aforementioned step S1011, it can be seen that each image column in the original image of uniform ground features corresponds to one detector element.

[0061] S1023: Using the original pixel grayscale value of the pixel as input, query the initial radiometric correction lookup table corresponding to the second target detector to obtain the mapped corrected grayscale value.

[0062] S1024: Replace the gray value of this pixel in the original image of the uniform ground features with the queried corrected gray value.

[0063] S1025: After traversing and processing all pixels in the original image of the uniform land cover, a preliminary corrected image of the original image of the uniform land cover is generated.

[0064] S103: For each uniform ground feature image and its corresponding preliminary correction image, determine the original grayscale mean value corresponding to each probe element from the uniform ground feature image, and determine the grayscale mean value of the entire image from the preliminary correction image.

[0065] In this embodiment, each uniform ground feature image corresponds to a preliminary correction image.

[0066] In one possible implementation, when performing step S103, the following steps S1031-S1032 can be specifically performed: S1031: For each uniform ground feature image, calculate the average gray value of multiple columns of pixels corresponding to each probe element in the uniform ground feature image, and use it as the original average gray value of the probe element.

[0067] In this embodiment, in a uniform ground feature image, each detector element corresponds to multiple columns of pixels. The average grayscale value of each column of pixels corresponding to the detector element is calculated, and this average grayscale value is used as the original average grayscale value of the detector element. Figure 6 As shown, assume that the original grayscale mean of probe T1 is a1, the original grayscale mean of probe T2 is a2, and so on.

[0068] For each uniform map image, each probe corresponds to one original gray-scale mean. Therefore, for a single probe, there will be multiple original gray-scale means, which are calculated from different uniform ground feature images.

[0069] S1032: Calculate the mean gray value of the entire image of the preliminary corrected image corresponding to the uniform ground feature image.

[0070] In this embodiment, each preliminary corrected image corresponds to a mean grayscale value for the entire image, such as... Figure 6 As shown, assume that the mean grayscale value of the entire image of the preliminary corrected image corresponding to the current uniform ground feature image is Mean.

[0071] S104: For each probe element, calculate an offset corresponding to the original gray-scale mean based on the original gray-scale mean of the probe element, the gray-scale mean of the entire image, and the initial radiometric correction lookup table of the probe element; wherein, each probe element corresponds to the offset of the original gray-scale mean determined from multiple uniform ground feature images of different sizes.

[0072] In this embodiment, the offset is the amount of adjustment required to adjust the original grayscale mean to a value such that when the adjusted value is used as input to query the initial radiometric correction lookup table, the output is the grayscale mean of the entire image.

[0073] In one possible implementation, when performing step S104, the following steps S1041-S1042 can be specifically performed: S1041: For each detector element, with the average grayscale value of the entire image as the target output value, look up the initial radiometric correction lookup table for that detector element in reverse to obtain the expected input value required for the output of the initial radiometric correction lookup table to reach the target output value.

[0074] In this embodiment, such as Figure 6 As shown, for each probe, there are multiple original gray-scale mean values, which are calculated from different uniform map images. Each preliminary corrected image corresponds to a total gray-scale mean value.

[0075] Using one of the probes T1 and one of the uniform map images ( Figure 6 The uniform map image shown is used as an example for illustration. Figure 7 As shown, a portion of the initial radiometric correction lookup table corresponding to probe T1 is displayed, where 120-127 are the eight original pixel grayscale values ​​(i.e., the input values ​​of the initial radiometric correction lookup table), and x1-x8 are the eight corrected grayscale values ​​(i.e., the output values ​​of the initial radiometric correction lookup table). Figure 7 In the image, the double-headed arrows represent a one-to-one mapping between the original pixel grayscale values ​​and the corrected grayscale values.

[0076] In this embodiment, such as Figure 8 As shown, for probe T1, using the original grayscale mean value a1 corresponding to probe T1 in the uniform ground cover image as the input value, the initial radiometric correction lookup table for probe T1 is consulted to obtain the output corrected grayscale value. Ideally (i.e., assuming the initial radiometric correction lookup table is correct), the output corrected grayscale value should be the same as the mean grayscale value Mean of the entire image of the preliminary corrected image corresponding to the uniform ground cover image.

[0077] If the output corrected grayscale value differs from the mean grayscale value of the entire image (Mean), it indicates a deviation in the initial radiometric correction lookup table. In this case, the mean grayscale value of the entire image (Mean) is used as the target output value of the initial radiometric correction lookup table for probe T1. The initial radiometric correction lookup table is then queried in reverse to obtain the expected input value required for the output of the initial radiometric correction lookup table to reach the target output value (Mean).

[0078] S1042: Calculate the difference between the expected input value and the original grayscale mean, and use it as an offset of the probe corresponding to the original grayscale mean, so as to obtain the offset of the probe corresponding to each original grayscale mean based on the original grayscale mean of each uniform ground object image.

[0079] Following the example above, such as Figure 8As shown, assuming the expected input value b1 is 123, the difference between the original grayscale mean a1 and the expected input value b1 is b1-a1=123-a1. This difference (b1-a1=123-a1) is used as an offset of probe T1 corresponding to the original grayscale mean a1.

[0080] Based on the original grayscale mean of each uniform ground feature image, probe T1 can calculate an offset corresponding to each original grayscale mean. That is, after traversing all uniform ground feature images and the preliminary correction image, each probe can obtain an offset corresponding to each of the multiple different original column means.

[0081] S105: For each detector element, based on the offset corresponding to each original gray-scale mean value of the detector element, the correction gray-scale value corresponding to the original pixel gray-scale value that is the same as the original gray-scale mean value in the initial radiometric correction lookup table of the detector element is moved to establish a new mapping relationship, and the calibrated radiometric correction lookup table corresponding to the detector element is obtained.

[0082] In one possible implementation, when performing step S105, the specific steps S1051-S1054 can be performed as follows: S1051: For each detector element, determine the gray values ​​of each original pixel that have the same mean original gray value as the detector element from the initial radiometric correction lookup table corresponding to the detector element, and use them as the target original pixel gray values.

[0083] For example, taking one of the original grayscale average values ​​a1 corresponding to probe T1 as an example, for probe T1, the offset of the original grayscale average value a1 obtained through the above example is 123-a1. If a1=120, as... Figure 7 As shown, the original pixel gray value 120, which is the same as the original gray mean a1 corresponding to probe T1 (belonging to the initial radiometric correction lookup table corresponding to probe T1), is determined, and the original pixel gray value 120 is used as the target original pixel gray value.

[0084] S1052: For each target original pixel grayscale value, add its corresponding offset to the target original pixel grayscale value to obtain the offset original pixel grayscale value.

[0085] For example, for a target original pixel grayscale value of 120, add its corresponding offset 120+123-a1 to the target original pixel grayscale value, where a1=120, so the original pixel grayscale value after offset is 123.

[0086] S1053: Using the original pixel grayscale value of the target as input, query the initial radiometric correction lookup table of the detector element to obtain the corrected grayscale value of the target.

[0087] For example, such as Figure 7 As shown, using the original pixel grayscale value of 120 as input, the corrected grayscale value of the target can be obtained by querying the initial radiometric correction lookup table of probe T1.

[0088] S1054: Move the target corrected gray value in the initial radiometric correction lookup table to the corrected gray value corresponding to the original pixel gray value after the offset, so as to establish a new mapping relationship between the original pixel gray value after the offset and the target corrected gray value, thereby forming the calibrated radiometric correction lookup table corresponding to the detector.

[0089] For example, such as Figure 8 As shown, the target corrected gray value x1 in the initial radiometric correction lookup table corresponding to probe T1 is moved to the corrected gray value corresponding to the original pixel gray value 123 after the offset, and a new mapping relationship is established between the original pixel gray value 123 after the offset and the target corrected gray value x1.

[0090] In this embodiment, the calibrated radiometric correction lookup table is used to perform relative radiometric calibration on the newly acquired remote sensing image.

[0091] In one possible implementation, such as Figure 8 As shown, the original pixel grayscale value corresponding to the target original pixel grayscale value 120 is 123 after offset. Therefore, the target corrected grayscale value x1 is moved to the corrected grayscale value corresponding to the original pixel grayscale value 123 after offset.

[0092] If the original pixel gray value corresponding to the target original pixel gray value 121 is also 123 after offset, then if the target corrected gray value x2 is to be moved to the corrected gray value corresponding to the original pixel gray value 123 after offset, since the original pixel gray value 123 has already established a new mapping relationship with x1, the new mapping relationship between the original pixel gray value 123 and the target corrected gray value x1 is retained according to the first-place principle.

[0093] If the original pixel grayscale value corresponding to the target original pixel grayscale value of 122 is also 125 after offset, then, Figure 8 As shown, the target corrected gray value x3 can be moved to the corrected gray value corresponding to the original pixel gray value 125 after the offset, and a new mapping relationship between the original pixel gray value 125 and the target corrected gray value x3 can be established.

[0094] The above method may result in missing values ​​in the target corrected grayscale value (i.e., some original pixel grayscale values ​​do not have corresponding corrected grayscale values ​​mapped in the lookup table), such as... Figure 8 As shown, the values ​​between x1 and x3 are missing values.

[0095] The specific reason is that, for example, for the first probe T1, using the first uniform ground image, the original grayscale mean of the first probe T1 is a1=120, and the corresponding offset of the first uniform ground image is 3; using the second uniform ground image, the original grayscale mean of the first probe T1 is a1=150, and the corresponding offset is 7. In other words, using different uniform ground images will produce different offsets corresponding to the original grayscale mean. Since the number of uniform ground images is limited, the original grayscale mean calculated using uniform ground images cannot cover all the original pixel grayscale values ​​(input values) in the radiometric correction lookup table, resulting in missing values ​​for the target correction grayscale values ​​of these uncovered original grayscale means.

[0096] If there are missing values ​​in the radiometric correction lookup table, gray-level mapping breakage is likely to occur, meaning that some original pixel gray values ​​cannot find the corresponding mapping target (target correction gray value). This will eventually cause obvious stripes and other visual anomalies in the relatively radiometrically calibrated image in dark areas (such as low-brightness areas like the sea surface or mountain shadows), which will seriously affect the image quality and the reliability of subsequent applications.

[0097] Therefore, to solve this problem, after forming the calibrated radiation correction lookup table corresponding to the detector element in step S1054, missing values ​​can be added to the calibrated radiation correction lookup table corresponding to the detector element through the following steps S1061-S1064: S1061: Traverse the calibrated radiometric correction lookup table corresponding to the detector, find the original pixel grayscale value that has not established a new mapping relationship, and use it as the original pixel grayscale value to be interpolated.

[0098] For example, such as Figure 8 As shown, the original pixel grayscale value to be interpolated is 124.

[0099] S1062: For each original pixel gray value to be interpolated, in the calibrated radiometric correction lookup table, search along the positive and negative directions of the original pixel gray value axis for the previous and next original pixel gray values ​​that are closest to it and have established a new mapping relationship, and obtain their corresponding target correction gray values.

[0100] For example, such as Figure 8 As shown, the grayscale value of the previous original pixel is 123, the grayscale value of the next original pixel is 125, the target correction grayscale value corresponding to the grayscale value of the previous original pixel 123 is x1, and the target correction grayscale value corresponding to the grayscale value of the next original pixel 125 is x3.

[0101] S1063: Based on the gray value of the previous original pixel, the gray value of the next original pixel, and its corresponding target correction gray value, perform linear interpolation calculation on the target correction gray value missing from the original pixel gray value to be interpolated.

[0102] In this example, based on the target correction gray value x1 and the target correction gray value x3, linear interpolation is performed on the target correction gray value missing from the original pixel gray value 124 to be interpolated.

[0103] S1064: The calculated interpolation result is used as the target corrected gray value mapped to the original pixel gray value to be interpolated, and is added to the calibrated radiometric correction lookup table to form a complete radiometric correction lookup table.

[0104] In this example, the interpolation result obtained by linear interpolation of x1 and x3 is used as the target correction gray value mapped to the original pixel gray value 124 to be interpolated, and is added to the calibrated radiometric correction lookup table.

[0105] In one possible implementation, after obtaining the calibrated radiometric correction lookup table, the newly acquired remote sensing image to be calibrated can be subjected to relative radiometric calibration through the following steps: Acquire the remote sensing images to be calibrated, captured by various sensors on the satellite; For each pixel in the remote sensing image to be calibrated, determine the image column in which the pixel is located, and determine the corresponding third target element based on the image column; Using the original pixel grayscale value of the pixel as input, query the calibrated radiometric correction lookup table corresponding to the third target detector to obtain the mapped target correction grayscale value; Replace the grayscale value of the pixel in the remote sensing image to be calibrated with the retrieved target correction grayscale value; After traversing and processing all pixels in the remote sensing image to be calibrated, a corrected remote sensing image is generated.

[0106] Based on the same technical concept, embodiments of this application also provide a calibration device for a radiation correction lookup table, such as... Figure 9 As shown, the device includes: The first acquisition module 901 is used to acquire target ground object images taken by the satellite through various detectors on the satellite in a yaw attitude, and generate an initial radiometric correction lookup table for each detector based on the target ground object images; the initial radiometric correction lookup table includes the mapping relationship between the original pixel grayscale value and the corrected grayscale value of the detector. The second acquisition module 902 is used to acquire multiple uniform ground object images taken by each of the probes on the satellite, and to correct each uniform ground object image using the initial radiometric correction lookup table to obtain multiple corresponding preliminary corrected images. The first determining module 903 is used to determine, for each uniform ground feature image and its corresponding preliminary correction image, an original grayscale mean value corresponding to each probe element from the uniform ground feature image, and to determine the overall grayscale mean value from the preliminary correction image. The calculation module 904 is used to calculate, for each of the probe elements, an offset corresponding to the original gray-scale mean of the probe element, based on the original gray-scale mean of the probe element, the gray-scale mean of the entire image, and the initial radiometric correction lookup table of the probe element; wherein, each of the probe elements corresponds to an offset corresponding to the original gray-scale mean determined from multiple uniform ground feature images of different sizes. The calibration module 905 is used to, for each of the detector elements, based on the offset corresponding to each of the original grayscale average values ​​corresponding to the detector element, move the correction grayscale value corresponding to the original pixel grayscale value that is the same as the original grayscale average value in the initial radiometric correction lookup table of the detector element, so as to establish a new mapping relationship and obtain the calibrated radiometric correction lookup table corresponding to the detector element.

[0107] Optionally, when the first acquisition module 901 acquires target ground feature images of the same ground feature taken by the satellite through various detectors on the satellite in a yaw attitude, and generates an initial radiometric correction lookup table for each detector based on the target ground feature images, it is specifically used for: The target image is obtained when a row of sensors on the satellite takes pictures of the same ground feature sequentially as the satellite moves while the satellite is in a yaw attitude. The target feature image is flattened so that each row of pixels in the target feature image corresponds to the same feature on the ground; each column of pixels in the target feature image corresponds to one detector element. For each column of pixels in the target feature image, calculate the first gray-level histogram of the corresponding probe element, and calculate the first cumulative probability density function of the probe element based on the first gray-level histogram. Based on all pixels of the entire target ground image, calculate its corresponding second gray-level histogram, and calculate the overall cumulative probability density function based on the second gray-level histogram; For each detector element, based on the first cumulative probability density function and the overall cumulative probability density function of the detector element, the corrected gray value to which each original pixel gray value of the detector element should be mapped is determined, so as to generate the initial radiometric correction lookup table of the detector element.

[0108] Optionally, the device further includes: The third acquisition module is used to acquire the first image taken by each of the detectors on the satellite after the first acquisition module 901 generates an initial radiometric correction lookup table for each of the detectors based on the target ground object image; The second determining module is used to determine the image column in which each pixel in the first image is located, and to determine the corresponding first target probe based on the image column. The query module is used to query the initial radiometric correction lookup table corresponding to the first target probe, with the original pixel grayscale value of the pixel as input. If the mapped correction grayscale value is found, the pixel is used as the first pixel; if the mapped correction grayscale value is not found, the pixel is used as the second pixel. The first supplementary module is used to, for each second pixel in the first image, determine two first pixels in the first image that are closest to the second pixel in the vertical or horizontal direction and are located on both sides of the first pixel, interpolate the corrected gray value of the second pixel according to the corrected gray value corresponding to each of the two first pixels, and use the result of the interpolation calculation as the corrected gray value of the original pixel gray value of the second pixel, and supplement it to the initial radiometric correction lookup table corresponding to the first target probe.

[0109] Optionally, when the second acquisition module 902 acquires multiple uniform ground feature images taken by each of the detectors on the satellite, and corrects each uniform ground feature image using the initial radiometric correction lookup table to obtain multiple corresponding preliminary corrected images, it is specifically used for: Acquire multiple original images of a uniform ground feature taken by various detectors on the satellite of at least one uniform ground feature; For each pixel in each original image of the uniform ground features, determine the image column in which the pixel is located, and determine the corresponding second target element based on the image column. Using the original pixel grayscale value of the pixel as input, the initial radiometric correction lookup table corresponding to the second target detector is queried to obtain the mapped corrected grayscale value; Replace the grayscale value of the pixel in the original image of the uniform ground features with the queried corrected grayscale value; After traversing and processing all pixels in the original image of uniform features, a preliminary corrected image of the original image of uniform features is generated.

[0110] Optionally, when the first determining module 903 determines an original grayscale mean value corresponding to each detector element from each uniform ground feature image and its corresponding preliminary correction image, and determines the overall grayscale mean value from the preliminary correction image, it is specifically used for: For each uniform ground feature image, the average gray value of the multiple columns of pixels corresponding to each probe element in the uniform ground feature image is calculated as the original average gray value of the probe element. Calculate the average grayscale value of the entire image of the preliminary corrected image corresponding to the uniform ground feature image.

[0111] Optionally, when the calculation module 904 calculates an offset corresponding to the original gray-scale mean for each detector element based on the original gray-scale mean of the detector element, the overall gray-scale mean, and the initial radiometric correction lookup table of the detector element, it is specifically used for: For each of the detector elements, with the average grayscale value of the entire image as the target output value, the initial radiometric correction lookup table for that detector element is looked up in reverse to obtain the expected input value required for the output of the initial radiometric correction lookup table to reach the target output value. The difference between the expected input value and the original grayscale mean is calculated as an offset of the probe corresponding to the original grayscale mean, so as to obtain the offset of the probe corresponding to each original grayscale mean based on the original grayscale mean of each uniform ground object image.

[0112] Optionally, when the calibration module 905 is used to move the corrected gray value corresponding to the original pixel gray value with the same original gray value in the initial radiometric correction lookup table of the detector for each detector element, based on the offset corresponding to each of the original gray-scale mean values ​​of the detector element, to establish a new mapping relationship and obtain the calibrated radiometric correction lookup table corresponding to the detector element, it is specifically used for: For each detector element, the gray values ​​of each original pixel that have the same mean original gray value as the detector element are determined from the initial radiometric correction lookup table corresponding to the detector element, and are used as the target original pixel gray values. For each target original pixel grayscale value, add its corresponding offset to the target original pixel grayscale value to obtain the offset original pixel grayscale value; Using the original pixel grayscale value of the target as input, the initial radiometric correction lookup table of the probe is queried to obtain the target corrected grayscale value; The target corrected gray value in the initial radiometric correction lookup table is moved to the corrected gray value corresponding to the original pixel gray value after the offset, so as to establish a new mapping relationship between the original pixel gray value after the offset and the target corrected gray value, thereby forming the calibrated radiometric correction lookup table corresponding to the detector.

[0113] Optionally, the device further includes: The lookup module is used to traverse the calibrated radiometric correction lookup table corresponding to the detector and find the original pixel gray value that has not established a new mapping relationship, which is used as the original pixel gray value to be interpolated. The search module is used to search for the closest original pixel gray value with a new mapping relationship in the positive and negative directions of the original pixel gray value axis in the calibrated radiometric correction lookup table for each original pixel gray value to be interpolated, and obtain their corresponding target correction gray values. The interpolation calculation module is used to perform linear interpolation calculation on the target correction gray value missing from the original pixel gray value to be interpolated, based on the previous original pixel gray value, the next original pixel gray value, and its corresponding target correction gray value. The second supplementary module is used to supplement the calibrated radiometric correction lookup table with the calculated interpolation result as the target corrected gray value mapped to the original pixel gray value to be interpolated, so as to form a complete radiometric correction lookup table.

[0114] Figure 10 A schematic diagram of an electronic device provided in this application embodiment includes: a processor 1001, a memory 1002, and a bus 10010. The memory 1002 stores machine-readable instructions executable by the processor 1001. When the electronic device runs the above-described information processing method, the processor 1001 and the memory 1002 communicate through the bus 10010. The processor 1001 executes the machine-readable instructions to perform the steps of the method described in Embodiment 1.

[0115] This application also provides a computer-readable storage medium storing a computer program, which, when executed by a processor, performs the steps described in Embodiment 1.

[0116] Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the devices, electronic devices, and computer-readable storage media described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0117] In the several embodiments provided in this application, it should be understood that the disclosed methods, apparatuses, electronic devices, and computer-readable storage media can be implemented in other ways. The apparatus embodiments described above are merely illustrative. For example, the division of modules is only a logical functional division, and in actual implementation, there may be other division methods. Furthermore, multiple modules or components may be combined or integrated into another system, or some features may be ignored or not executed. Additionally, the displayed or discussed mutual couplings, direct couplings, or communication connections may be through some communication interfaces; indirect couplings or communication connections between devices or modules may be electrical, mechanical, or other forms.

[0118] The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units; that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to achieve the purpose of this embodiment according to actual needs.

[0119] In addition, the functional units in the various embodiments of this application can be integrated into one processing unit, or each unit can exist physically separately, or two or more units can be integrated into one unit.

[0120] If the aforementioned functions are implemented as software functional units and sold or used as independent products, they can be stored in a processor-executable, non-volatile, computer-readable storage medium. Based on this understanding, the technical solution of this application, in essence, or the part that contributes to the prior art, or a portion of the technical solution, can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes several instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the methods described in the various embodiments of this application. The aforementioned storage medium includes various media capable of storing program code, such as USB flash drives, portable hard drives, read-only memory (ROM), random access memory (RAM), magnetic disks, or optical disks.

[0121] Finally, it should be noted that the above-described embodiments are merely specific implementations of this application, used to illustrate the technical solutions of this application, and not to limit them. The scope of protection of this application is not limited thereto. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that any person skilled in the art can still modify or easily conceive of changes to the technical solutions described in the foregoing embodiments, or make equivalent substitutions for some of the technical features, within the scope of the technology disclosed in this application. Such modifications, changes, or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this application, and should all be covered within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of protection of the claims.

Claims

1. A calibration method for a radiation correction lookup table, characterized in that, include: Acquire target ground object images of the same ground object taken by the satellite through various detectors on the satellite in a yaw attitude, and generate an initial radiometric correction lookup table for each detector based on the target ground object images; The initial radiometric correction lookup table includes the mapping relationship between the original pixel grayscale values ​​and the corrected grayscale values ​​of the detector. Multiple images of uniform ground features taken by various detectors on the satellite are acquired. The initial radiometric correction lookup table is used to correct each image of uniform ground features to obtain multiple corresponding preliminary corrected images. For each uniform ground feature image and its corresponding preliminary correction image, an original grayscale mean value corresponding to each probe element is determined from the uniform ground feature image, and the grayscale mean value of the entire image is determined from the preliminary correction image. For each of the probe elements, an offset corresponding to the original gray-scale mean is calculated based on the original gray-scale mean of the probe element, the gray-scale mean of the entire image, and the initial radiometric correction lookup table of the probe element; wherein, each of the probe elements corresponds to the offset of the original gray-scale mean determined from multiple uniform ground feature images of different sizes. For each detector element, based on the offset corresponding to each of the original grayscale average values ​​corresponding to the detector element, the correction grayscale value corresponding to the original pixel grayscale value that is the same as the original grayscale average value in the initial radiometric correction lookup table of the detector element is moved to establish a new mapping relationship, thereby obtaining the calibrated radiometric correction lookup table corresponding to the detector element.

2. The method according to claim 1, characterized in that, The process of acquiring target ground feature images taken by the satellite in a yaw attitude through various detectors on the satellite at the same ground feature, and generating an initial radiometric correction lookup table for each detector based on the target ground feature images, includes: The target image is obtained when a row of sensors on the satellite takes pictures of the same ground feature sequentially as the satellite moves while the satellite is in a yaw attitude. The target feature image is flattened so that each row of pixels in the target feature image corresponds to the same feature on the ground; each column of pixels in the target feature image corresponds to one detector element. For each column of pixels in the target feature image, calculate the first gray-level histogram of the corresponding probe element, and calculate the first cumulative probability density function of the probe element based on the first gray-level histogram. Based on all pixels of the entire target ground image, calculate its corresponding second gray-level histogram, and calculate the overall cumulative probability density function based on the second gray-level histogram; For each detector element, based on the first cumulative probability density function and the overall cumulative probability density function of the detector element, the corrected gray value to which each original pixel gray value of the detector element should be mapped is determined, so as to generate the initial radiometric correction lookup table of the detector element.

3. The method according to claim 1, characterized in that, After generating an initial radiometric correction lookup table for each of the detectors based on the target feature image, the method further includes: Acquire first images taken by each probe on the satellite; For each pixel in the first image, determine the image column in which the pixel is located, and determine the corresponding first target detector based on the image column; Using the original pixel grayscale value of the pixel as input, the initial radiometric correction lookup table corresponding to the first target detector is queried. If the mapped corrected grayscale value is found, the pixel is taken as the first pixel; if the mapped corrected grayscale value is not found, the pixel is taken as the second pixel. For each second pixel in the first image, determine the two first pixels in the first image that are closest to the second pixel in the vertical or horizontal direction and are located on both sides of the first pixel. Based on the corrected gray values ​​retrieved for each of the two first pixels, interpolate the corrected gray value of the second pixel. Use the result of the interpolation calculation as the corrected gray value of the original pixel gray value of the second pixel and add it to the initial radiometric correction lookup table corresponding to the first target probe.

4. The method according to claim 1, characterized in that, The process involves acquiring multiple uniform ground feature images taken by various detectors on the satellite, and then using the initial radiometric correction lookup table to correct each uniform ground feature image to obtain multiple corresponding preliminary corrected images, including: Acquire multiple original images of a uniform ground feature taken by various detectors on the satellite of at least one uniform ground feature; For each pixel in each original image of the uniform ground features, determine the image column in which the pixel is located, and determine the corresponding second target element based on the image column. Using the original pixel grayscale value of the pixel as input, the initial radiometric correction lookup table corresponding to the second target detector is queried to obtain the mapped corrected grayscale value; Replace the grayscale value of the pixel in the original image of the uniform ground features with the queried corrected grayscale value; After traversing and processing all pixels in the original image of uniform features, a preliminary corrected image of the original image of uniform features is generated.

5. The method according to claim 1, characterized in that, For each uniform ground feature image and its corresponding preliminary corrected image, the process involves determining an original grayscale mean value for each detector element from the uniform ground feature image, and determining the overall grayscale mean value from the preliminary corrected image, including: For each uniform ground feature image, the average gray value of the multiple columns of pixels corresponding to each probe element in the uniform ground feature image is calculated as the original average gray value of the probe element. Calculate the average grayscale value of the entire image of the preliminary corrected image corresponding to the uniform ground feature image.

6. The method according to claim 5, characterized in that, For each of the detector elements, based on the original grayscale mean of the detector element, the overall grayscale mean of the image, and the initial radiometric correction lookup table for the detector element, an offset corresponding to the original grayscale mean of the detector element is calculated, including: For each of the detector elements, with the average grayscale value of the entire image as the target output value, the initial radiometric correction lookup table for that detector element is looked up in reverse to obtain the expected input value required for the output of the initial radiometric correction lookup table to reach the target output value. The difference between the expected input value and the original grayscale mean is calculated as an offset of the probe corresponding to the original grayscale mean, so as to obtain the offset of the probe corresponding to each original grayscale mean based on the original grayscale mean of each uniform ground object image.

7. The method according to claim 1, characterized in that, For each detector element, based on the offset corresponding to each of the original grayscale averages for that detector element, the corrected grayscale values ​​corresponding to the original pixel grayscale values ​​with the same original grayscale averages in the initial radiometric correction lookup table for that detector element are shifted to establish a new mapping relationship, thereby obtaining the calibrated radiometric correction lookup table corresponding to that detector element, including: For each detector element, the gray values ​​of each original pixel that have the same mean original gray value as the detector element are determined from the initial radiometric correction lookup table corresponding to the detector element, and are used as the target original pixel gray values. For each target original pixel grayscale value, add its corresponding offset to the target original pixel grayscale value to obtain the offset original pixel grayscale value; Using the original pixel grayscale value of the target as input, the initial radiometric correction lookup table of the probe is queried to obtain the target corrected grayscale value; The target corrected gray value in the initial radiometric correction lookup table is moved to the corrected gray value corresponding to the original pixel gray value after the offset, so as to establish a new mapping relationship between the original pixel gray value after the offset and the target corrected gray value, thereby forming the calibrated radiometric correction lookup table corresponding to the detector.

8. The method according to claim 7, characterized in that, After obtaining the calibrated radiation correction lookup table corresponding to the detector element, the method further includes: Traverse the calibrated radiometric correction lookup table corresponding to the detector, find the original pixel gray value that has not established a new mapping relationship, and use it as the original pixel gray value to be interpolated. For each original pixel gray value to be interpolated, in the calibrated radiometric correction lookup table, search along the positive and negative directions of the original pixel gray value axis for the previous and next original pixel gray values ​​that are closest to it and have established a new mapping relationship, and obtain their corresponding target correction gray values. Based on the previous original pixel gray value, the next original pixel gray value, and its corresponding target correction gray value, linear interpolation is performed on the target correction gray value missing from the original pixel gray value to be interpolated. The calculated interpolation result is used as the target corrected gray value mapped to the original pixel gray value to be interpolated, and is added to the calibrated radiometric correction lookup table to form a complete radiometric correction lookup table.

9. A calibration device for a radiation correction lookup table, characterized in that, include: The first acquisition module is used to acquire target ground object images taken by the satellite through various detectors on the satellite in a yaw attitude, and generate an initial radiometric correction lookup table for each detector based on the target ground object images; The initial radiometric correction lookup table includes the mapping relationship between the original pixel grayscale values ​​and the corrected grayscale values ​​of the detector. The second acquisition module is used to acquire multiple uniform ground object images taken by each of the probes on the satellite, and to correct each uniform ground object image using the initial radiometric correction lookup table to obtain multiple corresponding preliminary corrected images. The first determining module is used to determine, for each uniform ground feature image and its corresponding preliminary correction image, an original grayscale mean value corresponding to each probe element from the uniform ground feature image, and to determine the grayscale mean value of the entire image from the preliminary correction image; The calculation module is used to calculate, for each of the probe elements, an offset corresponding to the original gray-scale mean of the probe element, based on the original gray-scale mean of the probe element, the gray-scale mean of the entire image, and the initial radiometric correction lookup table of the probe element; wherein, each of the probe elements corresponds to an offset corresponding to the original gray-scale mean determined from multiple uniform ground feature images of different sizes. The calibration module is used to, for each of the detector elements, based on the offset corresponding to each of the original grayscale average values ​​corresponding to the detector element, move the correction grayscale value corresponding to the original pixel grayscale value that is the same as the original grayscale average value in the initial radiometric correction lookup table of the detector element, so as to establish a new mapping relationship and obtain the calibrated radiometric correction lookup table corresponding to the detector element.

10. An electronic device, characterized in that, include: The device includes a processor, a memory, and a bus, wherein the memory stores machine-readable instructions executable by the processor, and when the electronic device is in operation, the processor communicates with the memory via the bus, and the machine-readable instructions, when executed by the processor, perform the steps of the method as described in any one of claims 1 to 8.

11. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores a computer program that, when executed by a processor, performs the steps of the method as described in any one of claims 1 to 8.

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