A modulation transfer function self-correction method and device, electronic equipment and medium

Abstract

The application discloses a modulation transfer function self-correction method and device, electronic equipment and medium. The method comprises the following steps: acquiring an imaging system modulation transfer function and an on-orbit image modulation transfer function; wherein the imaging system modulation transfer function is calculated according to a polarization imager parameter; the on-orbit image modulation transfer function is calculated according to an on-orbit image; a target atmospheric modulation transfer function is calculated by using a ground target signal image and an atmospheric top output signal image; wherein the ground target signal image is determined based on a ground surface radiance; the atmospheric top output signal image is determined based on an atmospheric top radiance; and modulation transfer function self-correction is performed according to the target atmospheric modulation transfer function, the imaging system modulation transfer function and the on-orbit image modulation transfer function. According to the technical scheme, the atmospheric modulation transfer function can be accurately calculated, so that the estimation accuracy of the on-orbit image modulation transfer function is improved.

Description

Technical Field

[0001] This invention relates to the field of multi-dimensional remote sensing optical information fusion detection technology, and in particular to a modulation transfer function self-calibration method, device, electronic device and medium. Background Technology

[0002] The Modulation Transfer Function (MTF) is a core performance indicator of optical satellite payloads, used to describe the sensor's ability to resolve optical information and form spatial details. The MTF measured by an optical satellite in orbit is obtained by cascading the imaging system MTF and the atmospheric MTF. Atmospheric radiation, as the medium for transmitting optical signals, can blur high-frequency details in the image, severely affecting the accuracy of MTF measurements.

[0003] Currently, on-orbit MTF measurements of optical satellites widely employ methods such as the edge method. Atmospheric MTF estimation is mainly achieved through two approaches: one is to perform atmospheric correction on satellite images before estimating the MTF, and the other is to directly subtract atmospheric influences using atmospheric MTF models such as small-angle scattering approximation and the equivalence principle. Both approaches require atmospheric information that is synchronized with the satellite imaging time and space.

[0004] Existing methods for acquiring atmospheric parameters have significant shortcomings: ground-based observation data suffers from point-to-area matching issues, other satellite atmospheric products exhibit spatiotemporal and geometric matching problems, and the resolution of satellite-borne synchronous correction instruments is far lower than that of the main payload, making them unable to handle situations where atmospheric distribution within the field of view is uneven. Furthermore, existing atmospheric MTF approximation models generally suffer from limitations such as theoretical simplification and poor universality, making it difficult to meet the application requirements of satellite-based quantitative, high-precision, and high spatial resolution. Therefore, there is an urgent need for a technical solution that can accurately acquire atmospheric MTF and improve the accuracy of on-orbit MTF estimation. Summary of the Invention

[0005] This invention provides a modulation transfer function self-calibration method, apparatus, electronic device, and medium, which can accurately calculate the atmospheric modulation transfer function, thereby improving the estimation accuracy of the modulation transfer function of on-orbit images.

[0006] According to one aspect of the present invention, a modulation transfer function self-calibration method is provided, the method comprising: The modulation transfer function of the imaging system and the modulation transfer function of the on-orbit image are obtained; wherein, the modulation transfer function of the imaging system is calculated based on the parameters of the polarization imager; and the modulation transfer function of the on-orbit image is calculated based on the on-orbit image. The atmospheric modulation transfer function of the target is calculated using ground target signal images and atmospheric top output signal images; wherein the ground target signal images are determined based on surface radiance; and the atmospheric top output signal images are determined based on atmospheric top radiance. Modulation transfer function self-calibration is performed based on the target atmospheric modulation transfer function, the imaging system modulation transfer function, and the on-orbit image modulation transfer function.

[0007] According to another aspect of the present invention, a modulation transfer function self-calibration device is provided, the device comprising: The modulation transfer function acquisition module is used to acquire the modulation transfer function of the imaging system and the modulation transfer function of the on-orbit image; wherein, the modulation transfer function of the imaging system is calculated based on the parameters of the polarization imager; and the modulation transfer function of the on-orbit image is calculated based on the on-orbit image. The target atmospheric modulation transfer function calculation module is used to calculate the target atmospheric modulation transfer function using ground target signal images and atmospheric top output signal images; wherein, the ground target signal images are determined based on surface radiance; and the atmospheric top output signal images are determined based on atmospheric top radiance. The modulation transfer function self-calibration module is used to perform modulation transfer function self-calibration based on the target atmospheric modulation transfer function, the imaging system modulation transfer function, and the theoretical atmospheric modulation transfer function.

[0008] According to another aspect of the present invention, an electronic device is provided, the electronic device comprising: At least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores a computer program executable by the at least one processor, the computer program being executed by the at least one processor to enable the at least one processor to perform a modulation transfer function self-calibration method according to any embodiment of the present invention.

[0009] According to another aspect of the present invention, a computer-readable storage medium is provided, the computer-readable storage medium storing computer instructions for causing a processor to execute and implement a modulation transfer function self-calibration method according to any embodiment of the present invention.

[0010] The technical solution of this invention obtains the modulation transfer function (MJF) of the imaging system and the MJF of the on-orbit image; calculates the atmospheric MJF of the target using ground target signal images and atmospheric top output signal images; and performs self-calibration of the MJF based on the atmospheric MJF, the imaging system MJF, and the on-orbit image MJF. This technical solution can accurately calculate the atmospheric MJF, thereby improving the estimation accuracy of the on-orbit image MJF.

[0011] It should be understood that the description in this section is not intended to identify key or essential features of the embodiments of the present invention, nor is it intended to limit the scope of the invention. Other features of the invention will become readily apparent from the following description. Attached Figure Description

[0012] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0013] Figure 1 This is a flowchart of a modulation transfer function self-calibration method provided in Embodiment 1 of the present invention; Figure 2 This is a schematic diagram of the principle of MTF detection based on the edge method provided in Embodiment 1 of this application; Figure 3 A schematic diagram of on-orbit optical modulation transfer function enhancement based on high-altitude, high-temperature, and high-velocity detection provided in Embodiment 1 of this application; Figure 4 This is a schematic diagram of a modulation transfer function self-calibration process provided in Embodiment 2 of the present invention; Figure 5 This is a schematic diagram of the structure of a modulation transfer function self-calibration device provided in Embodiment 3 of the present invention; Figure 6 This is a schematic diagram of the structure of an electronic device that implements a modulation transfer function self-calibration method according to an embodiment of the present invention. Detailed Implementation

[0014] To enable those skilled in the art to better understand the present invention, the technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention.

[0015] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate so that the embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0016] Example 1 Figure 1 This is a flowchart of a modulation transfer function self-calibration method according to Embodiment 1 of the present invention. This embodiment is applicable to situations where the modulation transfer function is self-calibrated. The method can be executed by a modulation transfer function self-calibration device, which can be implemented in hardware and / or software and can be configured in a device. For example, the device can be a backend server or other device with communication and computing capabilities. Figure 1 As shown, the method includes: S110. Obtain the modulation transfer function of the imaging system and the modulation transfer function of the on-orbit image; wherein, the modulation transfer function of the imaging system is calculated based on the parameters of the polarization imager; and the modulation transfer function of the on-orbit image is calculated based on the on-orbit image.

[0017] In this scheme, a high-resolution, high-spectral, and high-polarization integrated polarization imager operates in the 400nm–900nm band, with a minimum spectral resolution of 5nm and a spatial resolution better than 10m. The imager employs a focal-plane polarization multispectral detector and a wide-spectrum, low-distortion off-axis three-reflection polarization optical system. By integrating multispectral strip filters and polarizers into the detector, a compact polarization detection system is formed, enabling multispectral polarization detection. Furthermore, an intelligent spectral restoration method is used to reconstruct multispectral polarization information into hyperspectral polarization data, thereby achieving efficient hyperspectral polarization remote sensing imaging.

[0018] The modulation transfer function of the imaging system is calculated based on the parameters of the polarization imager and is the theoretical modulation transfer function of the imaging system.

[0019] In this embodiment, linear system theory and the modulation transfer function of the imaging system are used. It can be obtained by cascading the MTF of each part of the imaging link: ; in, For optical lens MTF, For detector MTF, This refers to the MTF of the electronic system. When the passband of the imaging circuit is set very wide, the MTF degradation caused by the electronic circuit can be approximately ignored.

[0020] Furthermore, the MTF of an optical lens is mainly affected by diffraction and aberration, and is expressed as: ; in, , , Radial spatial frequency, The spatial cutoff frequency, The average wavelength of each channel. , The focal length of the optical system. The aperture of the optical system, denoted as the root mean square wavefront error of the wavelength.

[0021] In this scheme, the detector MTF is represented as: ; in, This refers to the detector element size.

[0022] Specifically, the on-orbit image modulation transfer function is calculated based on the on-orbit image.

[0023] In this embodiment, based on the edge-based MTF measurement method specified in ISO 12233, edge targets at small angles to the detector's row or column direction are selected on the satellite remote sensing image. Then, a step edge model of the target is established, and after derivative calculation and Fourier transformation, the on-orbit image modulation transfer function is finally obtained. The main steps include selecting the edge image, detecting and fitting the edge position, constructing the ESF, extracting the LSF, LSF trimming, Discrete Fourier Transform (DFT), and normalization.

[0024] Specifically, Figure 2 This is a schematic diagram illustrating the principle of MTF detection based on the edge-edge method provided in Embodiment 1 of this application. The edge-edge method evaluates the performance of the optical system by using images generated from edge-edge targets, i.e., targets with sharp edges. Figure 2 As shown, the main steps of the edge method include selecting the edge image, edge position detection and edge fitting, solving the edge spread function (ESF), solving the line spread function (LSF), and frequency domain change normalization required to obtain the MTF curve.

[0025] In this scheme, it is assumed that the included angle of the cutting edges is... The sampling interval of the inclined blade edge is Then ESF can be represented as: ; in, It is a step function. For point spread functions, A comb function, used for discrete sampling, divides continuous signals into intervals. The sampling is a discrete sequence. It is a spatial coordinate variable.

[0026] The LSF function can be obtained by performing finite differences on the ESF.

[0027] ; Performing a Fourier transform on the LSF yields the on-orbit image MTF: .

[0028] S120. Calculate the atmospheric modulation transfer function of the target using the ground target signal image and the top-of-atmosphere output signal image; wherein the ground target signal image is determined based on the surface radiance; and the top-of-atmosphere output signal image is determined based on the top-of-atmosphere radiance.

[0029] In this scheme, the radiative transmission process of satellite-acquired images is considered. The signal acquired by optical satellite imaging is transmitted from solar radiation through the atmosphere to the ground, reflected, and then transmitted through the atmosphere to the camera. The blurring caused by the atmosphere to the sensor image varies with changes in the atmospheric conditions. Based on the definition of the modulation transfer function, the radiation emitted from the target ground is taken as the input signal. By calculating the surface radiance based on reflectivity, a ground target signal image can be obtained.

[0030] In this embodiment, the top-of-atmosphere radiation is the output signal. The top-of-atmosphere radiance is calculated based on the radiative transfer equation, and the top-of-atmosphere output signal image can be obtained.

[0031] Furthermore, by calculating the ground target signal image and the atmospheric top output signal image, the modulation transfer function of the ground target signal and the modulation transfer function of the atmospheric top output signal are determined; then, using the ground target signal modulation transfer function and the atmospheric top output signal modulation transfer function, the target atmospheric modulation transfer function is calculated.

[0032] S130. Perform modulation transfer function self-calibration based on the target atmospheric modulation transfer function, the imaging system modulation transfer function, and the on-orbit image modulation transfer function.

[0033] In this scheme, the modulation transfer function of the on-orbit image measured by the optical satellite is obtained by cascading the modulation transfer function of the imaging system and the theoretical atmospheric modulation transfer function, that is: .

[0034] In this embodiment, the modulation transfer function is self-corrected by comparing the modulation transfer function of the on-orbit image, the modulation transfer function of the imaging system, and the modulation transfer function of the target atmosphere, so as to eliminate the influence of the atmosphere and the imaging system and improve the accuracy of the modulation transfer function.

[0035] Optionally, modulation transfer function self-calibration is performed based on the target atmospheric modulation transfer function, the imaging system modulation transfer function, and the on-orbit image modulation transfer function, including: The on-orbit image modulation transfer function is divided by the target atmospheric modulation transfer function to perform self-correction on the on-orbit image modulation transfer function; The self-calibration results are compared and verified based on the modulation transfer function of the imaging system.

[0036] In this scheme, the on-orbit image modulation transfer function is divided by the target atmospheric modulation transfer function to obtain the on-orbit image modulation transfer function after removing atmospheric effects, thus completing the self-correction of the on-orbit image modulation transfer function.

[0037] Furthermore, the modulation transfer function of the imaging system is compared with the modulation transfer function of the on-orbit image after atmospheric interference is removed. The difference between the two is determined to be within a preset threshold range. This serves as a comparative verification of the on-orbit image modulation transfer function after atmospheric interference removal, ensuring the accuracy and reliability of the correction results. Theoretically, the on-orbit image modulation transfer function after atmospheric interference removal should be consistent with the imaging system modulation transfer function. However, since the on-orbit image modulation transfer function is susceptible to interference from various practical factors, there is usually a certain deviation between the two. As long as this deviation is within the preset threshold range, the correction result is considered valid.

[0038] The technical solution of this invention involves calculating the modulation transfer function (MTF) of an imaging system using polarization imager parameters; acquiring the on-orbit image MTF using on-orbit images; calculating the target atmospheric MTF using ground target signal images and atmospheric top output signal images; and performing MTF self-calibration based on the target atmospheric MTF, the imaging system MTF, and the on-orbit image MTF. By implementing this technical solution, the atmospheric MTF can be accurately calculated, thereby improving the estimation accuracy of the on-orbit image MTF.

[0039] In this scheme, the atmosphere serves as the core medium for optical signal transmission, and its characteristics directly determine the satellite imaging quality and the performance of the image modulation transfer function (MTF). Because the atmosphere blurs high-frequency details in satellite images, it is often considered equivalent to a low-pass filter in the frequency domain. Currently, many scholars have systematically elucidated the mechanism of atmospheric MTF through a combination of experimental statistics and approximate modeling. Related research is mainly divided into two directions: atmospheric absorption and scattering MTF models and atmospheric turbulence MTF models.

[0040] In existing research, the most widely used method is the small-angle scattering ray tracing method, which derives an analytical integral formula for the MTF under a uniformly distributed path in the scattering medium. Based on this, and using the mutual coherence function method and heuristic analysis, approximate analytical expressions for the MTF in two limiting spatial frequency ranges—low frequency and high frequency—are obtained. In these expressions, the MTF is only related to the absorption and scattering optical thickness, where the high-frequency component equals the medium transmittance, the cutoff frequency is determined by both the particle characteristic radius and the light wavelength, and the absorption effect is independent of the spatial frequency. Subsequently, the results in the two limiting spatial frequency ranges are used as the complete form of the MTF, further broadening the spatial frequency applicability of this model.

[0041] The approximate model of the small-angle scattering modulation transfer function is extended to the following limit form: ; in, This represents the absorption coefficient, where absorption is incorporated into the model as an overall attenuation coefficient independent of the space angular frequency. Represents the scattering coefficient. Represents angular spatial frequency. Indicates optical path length. This is the cutoff frequency for atmospheric aerosols. For atmospheric aerosol components with larger particle diameters, such as smoke and haze... and It mainly depends on the size distribution of the aerosol, at which point the following conditions must be met. ,in Represents the radius of the main aerosol particles in the atmosphere.

[0042] The small-angle scattering approximation MTF has significant limitations in applicability. Atmospheric light scattering is the core physical mechanism determining the atmospheric scattering MTF, and the light scattering characteristics of different types of particles vary significantly. Therefore, the influence of the scattering phase function must be fully considered. To address this issue, some scholars have proposed an equivalence principle, establishing a correlation between the atmospheric scattering MTF and the intensity distribution of emitted light from a parallel-plane turbid medium under isotropic diffuse light source illumination.

[0043] When the incident light field intensity is a uniform isotropic diffuse field of unit value, the light field distribution on the image plane can be expressed as: ; Depend on The definition of a function can be derived as follows: ; Therefore, we get: ; In the formula, , and In spatial polar coordinates, For spatial frequency. According to the principle of dimensional consistency, the variables on both sides of the equation must be dimensionless; therefore, dimensionless values ​​are used respectively. and space angular frequency It is expressed that, under the small-angle limit condition, it satisfies .

[0044] .

[0045] This equivalence principle allows for the clarification of the general characteristics of the image degradation factor (MTF) in atmospheric turbidity across the entire spatial frequency domain, as well as its quantitative dependence on parameters such as optical thickness, scattering phase function type, single albedo, and asymmetry factor. However, this method has theoretical limitations. Its core reliance on the ideal illumination assumption of an "isotropic diffuse light source" makes it difficult to apply under complex atmospheric conditions, and it also requires comprehensive aerosol parameters. Nevertheless, the equivalence principle MTF method remains a valuable theoretical tool, providing important reference for elucidating the imaging degradation mechanism in turbid media. However, due to its idealized theoretical assumptions, strong dependence on medium parameters, and the complexity of engineering measurements, this method cannot be widely applied in practical testing.

[0046] In summary, to meet the application requirements of satellite quantification, high precision, and high spatial resolution, it is necessary to rely on real-time atmospheric sounding data and combine it with a more accurate atmospheric radiative transfer model in order to achieve a precise assessment of the impact of atmospheric MTF.

[0047] Specifically, for applications requiring quantitative, high-precision, and high spatial resolution satellite imaging, a three-high integrated detection system is adopted. This system combines high spatial resolution, high spectral density, and high polarization characteristics into a single entity, increasing the optical detection dimension. It elevates the traditional one-dimensional optical detection of electromagnetic wave intensity to three-dimensional detection (I, Q, U) of polarization information, providing unique new parameters such as the degree of linear polarization (DOLP), the angle of polarization (AOP), and the bidirectional polarization distribution function (BPDF). A high-precision atmospheric parameter inversion model is used to acquire the detector's high spatial resolution atmospheric parameters in real time and synchronously, achieving complete spatiotemporal resolution matching and real-time processing of image data and atmospheric parameters. Through radiative transfer model calculations, pixel-by-pixel calculations are performed to accurately calculate atmospheric scattering and absorption MTF, ensuring applicability to different atmospheric scenes and parameters while effectively supporting various target and environmental detection scenarios.

[0048] Furthermore, Figure 3This is a schematic diagram of on-orbit optical modulation transfer function enhancement based on high-altitude, high-temperature, and high-humidity detection, as provided in Embodiment 1 of this application. Figure 3 As shown, the high-altitude, high-frequency, and high-resonance polarization imager uses computational optics to calculate the atmospheric MTF pixel-by-pixel, enabling on-orbit self-calibration, self-improvement, and self-detection. By fusing spectral and polarization measurements, it can simultaneously acquire the spectral and polarization state information of targets, greatly enhancing the information dimensionality. It can be mounted on platforms such as satellites, space stations, airships, and UAVs for refined environmental monitoring, resource exploration, and military reconnaissance, including target identification, sea surface glare suppression, fragmented cloud height determination, smoke transmittance enhancement, and 3D remote sensing.

[0049] In this plan, such as Figure 3 As shown, the edge image is acquired in orbit using a high-precision atmospheric imager (HPI imager), simultaneously obtaining atmospheric spectral polarization information along the entire observation path. A high-precision atmospheric inversion model is used to decouple the "atmospheric signal" and the "surface signal," directly retrieving the precise content of atmospheric components such as aerosols and water vapor. Furthermore, a high-precision atmospheric correction model is used to perform atmospheric correction on the acquired in-orbit images, subtracting the effects of atmospheric scattering and absorption to restore the true edge image of the surface, achieving in-orbit self-correction.

[0050] In this embodiment, based on the edge image acquired in orbit by the three-high integrated polarization imager, the on-orbit MTF, which includes the coupling of atmospheric and imager system characteristics, is estimated by the tilted edge method; further, based on the edge image after self-calibration by the polarization imager, the same tilted edge method is used to estimate the imager's on-orbit MTF after deducting atmospheric influence; comparing the on-orbit MTF results before calibration, the three-high integrated polarization imager can achieve self-improvement of on-orbit MTF.

[0051] Furthermore, based on the payload parameters of the integrated high-altitude, high-temperature, and high-height imager, the theoretical MTF of the imager can be calculated through the imaging system model, enabling self-testing of the corrected on-orbit MTF. Based on the payload parameters of the integrated high-altitude, high-height, and high-height imager and the retrieved atmospheric parameters, the atmospheric MTF can be calculated through the atmospheric forward model. By comparing the difference between the on-orbit MTF containing the atmosphere before correction and the on-orbit MTF after correction, self-testing of the on-orbit MTF can also be achieved.

[0052] Employing a novel "self-calibration, self-improvement, and self-detection" detection system using a "high resolution, high spectrum, and high polarization" integrated polarization imager, the system can obtain synchronous atmospheric parameters for each pixel of the high-resolution detector through a high-precision atmospheric parameter inversion model. This achieves complete spatiotemporal resolution matching and real-time processing of image data and atmospheric parameters. Furthermore, the system performs atmospheric correction on the acquired high-resolution on-orbit images through a high-precision atmospheric correction model, eliminating the effects of atmospheric scattering and absorption, thus achieving self-calibration of the on-orbit images.

[0053] Example 2 Figure 4 This is a schematic diagram of a modulation transfer function self-calibration process provided in Embodiment 2 of the present invention. The relationship between this embodiment and the above embodiments is a detailed description of the target atmospheric modulation transfer function calculation process. Figure 4 As shown, the method includes: S410. Obtain the modulation transfer function of the imaging system and the modulation transfer function of the on-orbit image; wherein, the modulation transfer function of the imaging system is calculated based on the parameters of the polarization imager; and the modulation transfer function of the on-orbit image is calculated based on the on-orbit image.

[0054] S420: Acquire ground target signal images and top-of-atmosphere output signal images.

[0055] In this scheme, a corresponding ground target signal image is generated by acquiring the surface radiance; and a corresponding atmospheric top output signal image is generated by acquiring the atmospheric top radiance.

[0056] Optionally, acquire ground target signal images, including: Obtain the solar irradiance outside the atmosphere, atmospheric absorption coefficient, atmospheric downward transmission coefficient, surface reflectance, environmental reflectance, atmospheric hemispherical albedo, and the cosine value of the solar zenith angle. The surface radiance is calculated by combining the extra-atmospheric solar irradiance, the atmospheric absorption coefficient, the atmospheric downward transmission coefficient, the surface reflectance, the environmental reflectance, the atmospheric hemispherical albedo, and the cosine of the solar zenith angle. Based on the surface radiance, a corresponding ground target signal image is generated.

[0057] In this scheme, extra-atmospheric solar irradiance refers to the full-spectrum solar radiation energy received per unit area perpendicular to sunlight per unit time at the Earth's upper atmosphere and the average distance between the Earth and the Sun; atmospheric absorption coefficient refers to the absorption capacity of the atmosphere per unit length for solar radiation, used to describe the rate attenuation of radiation due to absorption during propagation in the atmosphere; atmospheric downward transmission coefficient refers to the proportion of solar radiation that is directly transmitted without being absorbed or scattered as it travels from the upper atmosphere down to the Earth's surface; surface reflectivity refers to the ratio of solar radiation flux reflected from the Earth's surface to the total radiation flux incident on the Earth's surface; environmental reflectivity refers to the proportion of reflection contribution of the surrounding environment (such as adjacent surfaces, sky diffuse reflection, and atmospheric multiple scattering) to the target point; atmospheric hemispherical albedo refers to the proportion of total hemispherical reflection of incident solar radiation by the atmosphere, including atmospheric molecular scattering, aerosol scattering, and cloud reflection; the cosine of the solar zenith angle refers to the angle between the sunlight and the local zenith (ground normal). The cosine value is used to characterize the degree of tilt of the sun's incidence.

[0058] In this embodiment, the solar irradiance outside the atmosphere is calculated by collecting direct solar radiation signals and combining them with radiation calibration parameters; the atmospheric absorption coefficient is calculated by collecting atmospheric component content and atmospheric thickness parameters and combining them with the absorption characteristic model of atmospheric components; the atmospheric downward transmission coefficient is calculated by collecting solar radiation flux outside the atmosphere and solar downward radiation flux reaching the Earth's surface, based on the ratio between the two; the surface reflectivity is calculated by collecting solar radiation flux reflected from the Earth's surface and total solar radiation flux reaching the Earth's surface, based on the ratio between the two; the environmental reflectivity is calculated by collecting solar radiation flux reflected from surrounding objects and total solar radiation flux reaching the environmental area, based on the ratio between the two; the atmospheric hemispherical albedo is calculated by collecting solar radiation flux scattered and reflected by the atmosphere and solar radiation flux incident on the top of the atmosphere, based on the ratio between the two; and the cosine value of the solar zenith angle is calculated by collecting the latitude of the observation point, the solar declination angle, and the solar hour angle, and substituting them into the formula for calculating the cosine value of the solar zenith angle.

[0059] Among them, surface radiance is the radiance emitted upwards after the Earth's surface reflects solar radiation.

[0060] In this scheme, the surface radiance is converted into digital grayscale values, and the two are positively correlated. Based on the digital grayscale values, corresponding ground target signal images are generated, where different grayscale values ​​correspond to different surface radiance ranges, thereby representing different ground target features.

[0061] By accurately acquiring key parameters such as solar irradiance outside the atmosphere, atmospheric absorption coefficient, atmospheric downward transmission coefficient, surface reflectance, environmental reflectance, atmospheric hemispherical albedo, and cosine value of solar zenith angle, the surface irradiance is accurately obtained through combined calculations, and ground target signal images are generated accordingly. This effectively improves the accuracy and stability of ground target feature representation, and provides solid data support and a reliable implementation method for high-precision, quantitative optical detection and atmospheric correction by satellites.

[0062] Optionally, the surface radiance is calculated by combining the extra-atmospheric solar irradiance, the atmospheric absorption coefficient, the atmospheric downward transmission coefficient, the surface reflectance, the environmental reflectance, the atmospheric hemispherical albedo, and the cosine of the solar zenith angle, including: The surface radiance is calculated using the following formula; ; in, Surface radiance, Solar irradiance outside the atmosphere. Atmospheric absorption coefficient, The downward transmission coefficient of the atmosphere. For surface reflectance, For environmental reflectivity, The atmospheric hemispherical albedo. It is the cosine of the solar zenith angle.

[0063] In this scheme, the basic radiation flux term is obtained by multiplying the solar irradiance outside the atmosphere, the cosine of the solar zenith angle, the atmospheric absorption coefficient, and the atmospheric downward transmission coefficient; the correction factor is obtained by calculating the surface reflectance, environmental reflectance, and atmospheric hemispherical albedo; and the surface radiance is obtained by multiplying the basic radiation flux term and the correction factor.

[0064] By constructing precise physical formulas that include extra-atmospheric solar irradiance, atmospheric absorption coefficient, atmospheric downward transmission coefficient, surface reflectance, environmental reflectance, atmospheric hemispherical albedo, and the cosine of the solar zenith angle, quantitative calculation of surface irradiance can be achieved. This fully couples atmospheric transmission, surface reflection, and environmental scattering effects, significantly improving the accuracy of surface irradiance calculation.

[0065] Optionally, acquire an image of the output signal from the top of the atmosphere, including: Acquire atmospheric path radiance, atmospheric upward direct transmission coefficient, atmospheric upward scattered transmission coefficient, and surface radiance; The atmospheric path radiance, the atmospheric upward direct transmission coefficient, the atmospheric upward scattered transmission coefficient, and the surface radiance are superimposed to obtain the radiance of the top of the atmosphere. Based on the atmospheric top radiance, a corresponding atmospheric top output signal image is generated.

[0066] In this scheme, atmospheric path radiance refers to the radiant energy emitted or reflected by the atmosphere per unit time, per unit solid angle, per unit area perpendicular to the direction of radiation propagation, and per unit wavelength interval; atmospheric upward direct transmission coefficient refers to the ratio of the energy of radiation emitted from the Earth's surface or a certain altitude and propagating upward in a straight line to the initial incident energy, under the condition that it is only absorbed and attenuated by the atmosphere and no scattering occurs; atmospheric upward scattering transmission coefficient refers to the ratio of the energy of diffuse or isotropic radiation emitted from the Earth's surface or a certain altitude, after being scattered by the atmosphere once or multiple times, to the initial incident energy, reaching the upper boundary of the atmosphere or the sensor along the observation direction.

[0067] Among them, atmospheric radiance is obtained based on satellite observation equipment.

[0068] In this embodiment, based on the atmospheric radiative transfer model, the observed geometric parameters and key atmospheric parameters are input, and the upward direct transmission component and the upward scattered transmission component of the atmosphere are separated. The upward direct transmission coefficient and the upward scattered transmission coefficient of the atmosphere are calculated respectively.

[0069] The basic radiation flux term is obtained by multiplying the solar irradiance outside the atmosphere, the cosine of the solar zenith angle, the atmospheric absorption coefficient, and the atmospheric downward transmission coefficient; the correction factor is obtained by calculating the surface reflectance, environmental reflectance, and atmospheric hemispherical albedo; and the surface radiance is obtained by multiplying the basic radiation flux term and the correction factor.

[0070] Among them, the radiance of the top of the atmosphere is the radiance from the Earth system measured by satellite sensors at an altitude outside the atmosphere.

[0071] Furthermore, based on the radiative transfer equation, the atmospheric path radiance, the upward direct transmission coefficient of the atmosphere, the upward scattered transmission coefficient of the atmosphere, and the surface radiance are superimposed to obtain the top atmospheric radiance.

[0072] In this scheme, the radiance of the top of the atmosphere is converted into a digital grayscale value, and the digital grayscale value is positively correlated with the radiance of the top of the atmosphere; based on the digital grayscale value, the corresponding radiance of the top of the atmosphere is generated.

[0073] By accurately acquiring atmospheric path radiance, atmospheric upward direct transmission coefficient, atmospheric upward scattering transmission coefficient, and surface radiance, and performing superposition calculations to obtain the top atmospheric radiance, the calculation fully considers the coupling effects of key physical processes such as atmospheric absorption, scattering, and surface reflection. Furthermore, by separating the direct and scattered transmission components through an atmospheric radiative transfer model, the accuracy of radiance calculation is improved.

[0074] Optionally, the atmospheric path radiance, the upward direct atmospheric transmission coefficient, the upward atmospheric scattering transmission coefficient, and the surface radiance are superimposed to obtain the top atmospheric radiance, including: The radiance of the top of the atmosphere is calculated using the following formula; ; in, This refers to the radiance at the top of the atmosphere. Atmospheric path radiance, This is the direct upward transmission coefficient of the atmosphere. This represents the upward scattering and transmission coefficient of the atmosphere. Solar irradiance outside the atmosphere. Atmospheric absorption coefficient, The downward transmission coefficient of the atmosphere. For surface reflectance, For environmental reflectivity, The atmospheric hemispherical albedo. It is the cosine of the solar zenith angle.

[0075] In this scheme, the basic radiation flux term is obtained by multiplying the solar irradiance outside the atmosphere, the cosine of the solar zenith angle, the atmospheric absorption coefficient, and the atmospheric downward transmission coefficient; the correction factor is obtained by calculating the surface reflectance, environmental reflectance, and atmospheric hemispherical albedo; and the surface radiance is obtained by multiplying the basic radiation flux term and the correction factor.

[0076] Furthermore, the surface radiance is multiplied by the upward direct atmospheric transmission coefficient to obtain the surface radiation component after upward direct atmospheric transmission. Based on the environmental reflectivity and combined with the upward atmospheric scattering transmission coefficient, the environmental radiation component after upward atmospheric scattering transmission is obtained. These two components are then superimposed to obtain the total contribution of surface and environmental reflection after upward atmospheric transmission. Finally, the atmospheric path radiance is added to the total contribution of surface and environmental reflection after atmospheric transmission to obtain the complete radiance of the top of the atmosphere.

[0077] By introducing a precise formula that includes atmospheric path radiance, atmospheric upward direct transmission coefficient and scattered transmission coefficient, surface reflectance, and proximity effect correction terms, the atmospheric top radiance is calculated. This not only fully describes the complete physical process of solar radiation through atmospheric absorption, downward transmission, surface reflection, atmospheric upward direct / scattered transmission, and the coupling effect of environmental reflection and atmospheric hemispherical albedo, but also achieves quantitative separation and precise expression of each component, effectively improving the numerical accuracy of atmospheric top radiance calculation.

[0078] S430. Calculate the ground target signal image and the top of the atmosphere output signal image to determine the ground target signal modulation transfer function and the top of the atmosphere output signal modulation transfer function.

[0079] Specifically, the edge-edge method is used to calculate the modulation transfer function of the ground target signal and the modulation transfer function of the output signal at the top of the atmosphere, respectively.

[0080] S440. Divide the modulation transfer function of the output signal at the top of the atmosphere with the modulation transfer function of the ground target signal to obtain the target atmospheric modulation transfer function.

[0081] In this scheme, starting from the definition of modulation transfer function, the radiation emitted from the target ground is taken as the input signal and the radiation from the top of the atmosphere is taken as the output signal. By solving the radiation transfer model and performing pixel-by-pixel simulation, the effects of atmospheric scattering and absorption can be accurately calculated. The target atmospheric modulation transfer function is obtained based on the ratio of the modulation transfer function of the output signal from the top of the atmosphere to the modulation transfer function of the ground target signal.

[0082] Specifically, the target atmospheric modulation transfer function is calculated using the following formula; ; in, Let be the target atmospheric modulation transfer function. The modulation transfer function for the output signal at the top of the atmosphere. This is the modulation transfer function for ground target signals.

[0083] S450. Perform modulation transfer function self-calibration based on the target atmospheric modulation transfer function, the imaging system modulation transfer function, and the on-orbit image modulation transfer function.

[0084] The technical solution of this invention involves: calculating the modulation transfer function (MTF) of the imaging system using polarization imager parameters; acquiring the on-orbit image MTF using on-orbit images; acquiring ground target signal images and atmospheric top output signal images; calculating the ground target signal MTF and atmospheric top output signal MTF based on the ground target signal images and atmospheric top output signal images; dividing the atmospheric top output signal MTF by the ground target signal MTF to obtain the target atmospheric MTF; and achieving self-correction of the MTF by comparing the on-orbit image MTF, the imaging system MTF, and the target atmospheric MTF. By implementing this technical solution, without relying on external atmospheric detection methods, real-time detection and inversion of pixel-by-pixel atmospheric parameters of the high spatial resolution sensor can be achieved based on the three-high system (high altitude, high temperature, high humidity, and high humidity), completing real-time correction of payload data, and thus achieving self-improvement of the optical MTF. Simultaneously, through radiative transfer model calculation, the atmospheric scattering and absorption MTF of high spatial resolution pixel-by-pixel can be accurately obtained, ensuring good applicability to different atmospheric scenes and parameters, and effectively applying it to actual testing.

[0085] This solution also supports target recognition applications in complex scenarios such as sea surface glare suppression, fragmented cloud height identification, and smoke transmittance enhancement, as well as the acquisition of multi-dimensional feature information in polarization, spectroscopy, and spatiotemporal dimensions.

[0086] Example 3 Figure 5 This is a schematic diagram of a modulation transfer function self-calibration device provided in Embodiment 3 of the present invention. Figure 5 As shown, the device includes: The modulation transfer function acquisition module 510 is used to acquire the modulation transfer function of the imaging system and the modulation transfer function of the on-orbit image; wherein, the modulation transfer function of the imaging system is calculated based on the parameters of the polarization imager; and the modulation transfer function of the on-orbit image is calculated based on the on-orbit image. The target atmospheric modulation transfer function calculation module 520 is used to calculate the target atmospheric modulation transfer function using a ground target signal image and an output signal image from the top of the atmosphere; wherein, the ground target signal image is determined based on the surface radiance; and the output signal image from the top of the atmosphere is determined based on the top of the atmosphere radiance. The modulation transfer function self-calibration module 530 is used to perform modulation transfer function self-calibration based on the target atmospheric modulation transfer function, the imaging system modulation transfer function, and the on-orbit image modulation transfer function.

[0087] Optionally, the target atmospheric modulation transfer function calculation module 520 includes: The image acquisition unit is used to acquire ground target signal images and atmospheric top output signal images; The modulation transfer function calculation unit is used to calculate the modulation transfer function of the ground target signal image and the output signal image of the top of the atmosphere to determine the modulation transfer function of the ground target signal and the modulation transfer function of the output signal of the top of the atmosphere. The target atmospheric modulation transfer function obtaining unit is used to divide the modulation transfer function of the output signal at the top of the atmosphere with the modulation transfer function of the ground target signal to obtain the target atmospheric modulation transfer function.

[0088] Optionally, the image acquisition unit includes: The parameter acquisition subunit is used to acquire the solar irradiance outside the atmosphere, atmospheric absorption coefficient, atmospheric downward transmission coefficient, surface reflectance, environmental reflectance, atmospheric hemispherical albedo, and the cosine value of the solar zenith angle. The surface radiance calculation subunit is used to combine the extra-atmosphere solar irradiance, the atmospheric absorption coefficient, the atmospheric downward transmission coefficient, the surface reflectance, the environmental reflectance, the atmospheric hemispherical albedo, and the cosine value of the solar zenith angle to calculate the surface radiance. The ground target signal image generation subunit is used to generate a corresponding ground target signal image based on the surface radiance.

[0089] Optional, surface radiance calculation subunit, specifically used for: The surface radiance is calculated using the following formula; ; in, Surface radiance, Solar irradiance outside the atmosphere. Atmospheric absorption coefficient, The downward transmission coefficient of the atmosphere. For surface reflectance, For environmental reflectivity, The atmospheric hemispherical albedo. It is the cosine of the solar zenith angle.

[0090] Optionally, the image acquisition unit includes: The subunit for acquiring radiance parameters of the top of the atmosphere is used to acquire atmospheric path radiance, direct transmission coefficient of the atmosphere upward, scattered transmission coefficient of the atmosphere upward, and surface radiance. The top atmospheric radiance sub-unit is used to superimpose the atmospheric path radiance, the upward direct transmission coefficient of the atmosphere, the upward scattered transmission coefficient of the atmosphere, and the surface radiance to obtain the top atmospheric radiance. The atmospheric top output signal image generation subunit is used to generate a corresponding atmospheric top output signal image based on the atmospheric top radiance.

[0091] Optionally, the sub-unit of the atmospheric top radiance is obtained, specifically for: The radiance of the top of the atmosphere is calculated using the following formula; ; in, This refers to the radiance at the top of the atmosphere. Atmospheric path radiance, This is the direct upward transmission coefficient of the atmosphere. This represents the upward scattering and transmission coefficient of the atmosphere. Solar irradiance outside the atmosphere. Atmospheric absorption coefficient, The downward transmission coefficient of the atmosphere. For surface reflectance, For environmental reflectivity, The atmospheric hemispherical albedo. It is the cosine of the solar zenith angle.

[0092] Optionally, the modulation transfer function self-calibration module 530 is specifically used for: The on-orbit image modulation transfer function is divided by the target atmospheric modulation transfer function to perform self-correction on the on-orbit image modulation transfer function; The self-calibration results are compared and verified based on the modulation transfer function of the imaging system.

[0093] The modulation transfer function self-calibration device provided in this embodiment of the invention can execute the modulation transfer function self-calibration method provided in any embodiment of the invention, and has the corresponding functional modules and beneficial effects of the method.

[0094] Example 4 Figure 6A schematic diagram of an electronic device 10, which can be used to implement embodiments of the present invention, is shown. The electronic device is intended to represent various forms of digital computers, such as laptop computers, desktop computers, workstations, personal digital assistants, servers, blade servers, mainframe computers, and other suitable computers. The electronic device can also represent various forms of mobile devices, such as personal digital processors, cellular phones, smartphones, wearable devices (e.g., helmets, glasses, watches, etc.), and other similar computing devices. The components shown herein, their connections and relationships, and their functions are merely illustrative and are not intended to limit the implementation of the invention described and / or claimed herein.

[0095] like Figure 6 As shown, the electronic device 10 includes at least one processor 11 and a memory, such as a read-only memory (ROM) 12 or a random access memory (RAM) 13, communicatively connected to the at least one processor 11. The memory stores computer programs executable by the at least one processor. The processor 11 can perform various appropriate actions and processes based on the computer program stored in the ROM 12 or loaded from storage unit 18 into the RAM 13. The RAM 13 can also store various programs and data required for the operation of the electronic device 10. The processor 11, ROM 12, and RAM 13 are interconnected via a bus 14. An input / output (I / O) interface 15 is also connected to the bus 14.

[0096] Multiple components in electronic device 10 are connected to I / O interface 15, including: input unit 16, such as keyboard, mouse, etc.; output unit 17, such as various types of displays, speakers, etc.; storage unit 18, such as disk, optical disk, etc.; and communication unit 19, such as network card, modem, wireless transceiver, etc. Communication unit 19 allows electronic device 10 to exchange information / data with other devices through computer networks such as the Internet and / or various telecommunications networks.

[0097] Processor 11 can be a variety of general-purpose and / or special-purpose processing components with processing and computing capabilities. Some examples of processor 11 include, but are not limited to, a central processing unit (CPU), a graphics processing unit (GPU), various special-purpose artificial intelligence (AI) computing chips, various processors running machine learning model algorithms, a digital signal processor (DSP), and any suitable processor, controller, microcontroller, etc. Processor 11 performs the various methods and processes described above, such as a modulation transfer function self-calibration method.

[0098] In some embodiments, a modulation transfer function self-calibration method may be implemented as a computer program tangibly contained in a computer-readable storage medium, such as storage unit 18. In some embodiments, part or all of the computer program may be loaded and / or mounted on electronic device 10 via ROM 12 and / or communication unit 19. When the computer program is loaded into RAM 13 and executed by processor 11, one or more steps of the modulation transfer function self-calibration method described above may be performed. Alternatively, in other embodiments, processor 11 may be configured to perform a modulation transfer function self-calibration method by any other suitable means (e.g., by means of firmware).

[0099] Various embodiments of the systems and techniques described above herein can be implemented in digital electronic circuit systems, integrated circuit systems, field-programmable gate arrays (FPGAs), application-specific integrated circuits (ASICs), application-specific standard products (ASSPs), system-on-a-chip (SoCs), complex programmable logic devices (CPLDs), computer hardware, firmware, software, and / or combinations thereof. These various embodiments may include implementations in one or more computer programs that can be executed and / or interpreted on a programmable system including at least one programmable processor, which may be a dedicated or general-purpose programmable processor, capable of receiving data and instructions from a storage system, at least one input device, and at least one output device, and transferring data and instructions to the storage system, the at least one input device, and the at least one output device.

[0100] Computer programs used to implement the methods of the present invention may be written in any combination of one or more programming languages. These computer programs may be provided to a processor of a general-purpose computer, a special-purpose computer, or other programmable data processing device, such that when executed by the processor, the computer programs cause the functions / operations specified in the flowcharts and / or block diagrams to be performed. The computer programs may be executed entirely on a machine, partially on a machine, or as a standalone software package, partially on a machine and partially on a remote machine, or entirely on a remote machine or server.

[0101] In the context of this invention, a computer-readable storage medium can be a tangible medium that may contain or store a computer program for use by or in conjunction with an instruction execution system, apparatus, or device. A computer-readable storage medium may include, but is not limited to, electronic, magnetic, optical, electromagnetic, infrared, or semiconductor systems, apparatus, or devices, or any suitable combination thereof. Alternatively, a computer-readable storage medium may be a machine-readable signal medium. More specific examples of machine-readable storage media include electrical connections based on one or more wires, portable computer disks, hard disks, random access memory (RAM), read-only memory (ROM), erasable programmable read-only memory (EPROM or flash memory), optical fibers, portable compact disk read-only memory (CD-ROM), optical storage devices, magnetic storage devices, or any suitable combination thereof.

[0102] To provide interaction with a user, the systems and techniques described herein can be implemented on an electronic device having: a display device (e.g., a CRT (cathode ray tube) or LCD (liquid crystal display) monitor) for displaying information to the user; and a keyboard and pointing device (e.g., a mouse or trackball) through which the user provides input to the electronic device. Other types of devices can also be used to provide interaction with the user; for example, feedback provided to the user can be any form of sensory feedback (e.g., visual feedback, auditory feedback, or tactile feedback); and input from the user can be received in any form (including sound input, voice input, or tactile input).

[0103] The systems and technologies described herein can be implemented in computing systems that include backend components (e.g., as data servers), or middleware components (e.g., application servers), or frontend components (e.g., user computers with graphical user interfaces or web browsers through which users can interact with implementations of the systems and technologies described herein), or any combination of such backend, middleware, or frontend components. The components of the system can be interconnected via digital data communication of any form or medium (e.g., communication networks). Examples of communication networks include local area networks (LANs), wide area networks (WANs), blockchain networks, and the Internet.

[0104] A computing system can include clients and servers. Clients and servers are generally located far apart and typically interact through communication networks. The client-server relationship is created by computer programs running on the respective computers and having a client-server relationship with each other. The server can be a cloud server, also known as a cloud computing server or cloud host, which is a hosting product within the cloud computing service system to address the shortcomings of traditional physical hosts and VPS services, such as high management difficulty and weak business scalability.

[0105] In particular, according to embodiments of the present invention, the processes described above with reference to the flowcharts can be implemented as computer software programs. For example, embodiments of the present invention include a computer program product comprising a computer program carried on a non-transitory computer-readable medium, the computer program containing program code for performing the methods shown in the flowcharts. In such embodiments, the computer program can be downloaded and installed from a network via communication unit 19, or installed from storage unit 18, or installed from ROM 12. When the computer program is executed by processor 11, it performs the functions defined in the methods of the embodiments of the present invention.

[0106] It should be understood that the various forms of processes shown above can be used, with steps reordered, added, or deleted. For example, the steps described in this invention can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution of this invention can be achieved, and this is not limited herein.

[0107] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for self-calibration of modulation transfer function, characterized in that, include: The modulation transfer function of the imaging system and the modulation transfer function of the on-orbit image are obtained; wherein, the modulation transfer function of the imaging system is calculated based on the parameters of the polarization imager; and the modulation transfer function of the on-orbit image is calculated based on the on-orbit image. The atmospheric modulation transfer function of the target is calculated using ground target signal images and atmospheric top output signal images; wherein the ground target signal images are determined based on surface radiance; and the atmospheric top output signal images are determined based on atmospheric top radiance. Modulation transfer function self-calibration is performed based on the target atmospheric modulation transfer function, the imaging system modulation transfer function, and the on-orbit image modulation transfer function.

2. The method according to claim 1, characterized in that, Using ground target signal images and top-of-atmosphere output signal images, the atmospheric modulation transfer function of the target is calculated, including: Acquire ground target signal images and atmospheric top output signal images; The modulation transfer function of the ground target signal and the modulation transfer function of the output signal from the top of the atmosphere are calculated and determined. The target atmospheric modulation transfer function is obtained by dividing the modulation transfer function of the output signal at the top of the atmosphere by the modulation transfer function of the ground target signal.

3. The method according to claim 2, characterized in that, Acquire ground target signal images, including: Obtain the solar irradiance outside the atmosphere, atmospheric absorption coefficient, atmospheric downward transmission coefficient, surface reflectance, environmental reflectance, atmospheric hemispherical albedo, and the cosine value of the solar zenith angle. The surface radiance is calculated by combining the extra-atmospheric solar irradiance, the atmospheric absorption coefficient, the atmospheric downward transmission coefficient, the surface reflectance, the environmental reflectance, the atmospheric hemispherical albedo, and the cosine of the solar zenith angle. Based on the surface radiance, a corresponding ground target signal image is generated.

4. The method according to claim 3, characterized in that, The Earth's surface radiance is calculated by combining the extra-atmospheric solar irradiance, the atmospheric absorption coefficient, the atmospheric downward transmission coefficient, the surface reflectance, the environmental reflectance, the atmospheric hemispherical albedo, and the cosine of the solar zenith angle. This includes: The surface radiance is calculated using the following formula; ； in, The surface radiance, Solar irradiance outside the atmosphere. Atmospheric absorption coefficient, The downward transmission coefficient of the atmosphere. For surface reflectance, For environmental reflectivity, The atmospheric hemispherical albedo. It is the cosine of the solar zenith angle.

5. The method according to claim 2, characterized in that, Acquire an image of the output signal from the top of the atmosphere, including: Acquire atmospheric path radiance, atmospheric upward direct transmission coefficient, atmospheric upward scattered transmission coefficient, and surface radiance; The atmospheric path radiance, the atmospheric upward direct transmission coefficient, the atmospheric upward scattered transmission coefficient, and the surface radiance are superimposed to obtain the radiance of the top of the atmosphere. Based on the atmospheric top radiance, a corresponding atmospheric top output signal image is generated.

6. The method according to claim 5, characterized in that, The atmospheric path radiance, the upward direct transmission coefficient of the atmosphere, the upward scattered transmission coefficient of the atmosphere, and the surface radiance are superimposed to obtain the radiance of the top of the atmosphere, including: The radiance of the top of the atmosphere is calculated using the following formula; ； in, This refers to the radiance at the top of the atmosphere. Atmospheric path radiance, This is the direct upward transmission coefficient of the atmosphere. This represents the upward scattering and transmission coefficient of the atmosphere. Solar irradiance outside the atmosphere. Atmospheric absorption coefficient, The downward transmission coefficient of the atmosphere. For surface reflectance, For environmental reflectivity, The atmospheric hemispherical albedo. It is the cosine of the solar zenith angle.

7. The method according to claim 1, characterized in that, Modulation transfer function self-calibration is performed based on the target atmospheric modulation transfer function, the imaging system modulation transfer function, and the on-orbit image modulation transfer function, including: The on-orbit image modulation transfer function is divided by the target atmospheric modulation transfer function to perform self-correction on the on-orbit image modulation transfer function; The self-calibration results are compared and verified based on the modulation transfer function of the imaging system.

8. A modulation transfer function self-calibration device, characterized in that, include: The modulation transfer function acquisition module is used to acquire the modulation transfer function of the imaging system and the modulation transfer function of the on-orbit image; wherein, the modulation transfer function of the imaging system is calculated based on the parameters of the polarization imager; and the modulation transfer function of the on-orbit image is calculated based on the on-orbit image. The target atmospheric modulation transfer function calculation module is used to calculate the target atmospheric modulation transfer function using ground target signal images and atmospheric top output signal images; wherein, the ground target signal images are determined based on surface radiance; and the atmospheric top output signal images are determined based on atmospheric top radiance. The modulation transfer function self-calibration module is used to perform modulation transfer function self-calibration based on the target atmospheric modulation transfer function, the imaging system modulation transfer function, and the on-orbit image modulation transfer function.

9. An electronic device, characterized in that, The electronic device includes: At least one processor; and a memory communicatively connected to the at least one processor; wherein the memory stores a computer program executable by the at least one processor, the computer program being executed by the at least one processor to enable the at least one processor to perform a modulation transfer function self-calibration method according to any one of claims 1-7.

10. A computer-readable storage medium, characterized in that, The computer-readable storage medium stores computer instructions that cause a processor to execute a modulation transfer function self-calibration method according to any one of claims 1-7.

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