PRNU Correction Method for Hyperspectral Imaging Spectrometer and Storage Medium

Abstract

A method for PRNU correction of a hyperspectral imaging spectrometer and a storage medium according to the present invention include obtaining multi-frame flat-field image data at two brightness levels through the integrating sphere flat-field image of a tungsten halogen light source, and calculating the standard deviation of the image means at the two brightness levels by a statistical method; using this standard deviation as a reference, selecting a laser wavelength for the bands of the hyperspectral imaging spectrometer, performing flat-field data acquisition and screening after decoherence, performing PRNU correction processing on the screened laser flat-field data to obtain correction coefficients; performing data interpolation on the PRNU correction coefficients of different wavelengths to obtain a set of PRNU correction coefficients at a high-resolution band; using the PRNU correction coefficients of different wavelengths can achieve high-precision PRNU correction of the hyperspectral imaging spectrometer data. The present invention uses the imaging focal plane die of the imaging spectrometer to perform high-resolution spectral flat-field imaging, can obtain the full-image surface PRNU correction parameters of all spectral channels of the spectrometer, the data volume of each spectral channel is large and the spectral drift problem does not need to be considered, and the correction accuracy is higher and the stability is better.

Description

Technical Field

[0001] The present invention relates to the field of existing PRNU correction technologies for imaging spectrometers, and particularly relates to a PRNU correction method and a storage medium for a hyperspectral imaging spectrometer. Background Art

[0002] In an imaging spectrometer, a CCD is usually used as a photoelectric device. The CCD described in the present invention is the photoelectric device in the imaging spectrometer, but it is not limited to the CCD and can also be a CMOS.

[0003] PRNU (Photo Response Non-Uniformity) pixel response non-uniformity refers to the phenomenon that the response values generated by each pixel in the CCD are different when irradiated by the same energy light intensity. In the field of hyperspectral imaging, in order to obtain an image with a high signal-to-noise ratio, a scientific-grade area array CCD is usually used as the photoelectric detection device during the period. The scientific-grade CCD has a deeper potential well and a larger pixel size, making the PRNU phenomenon of the obtained image more obvious. The CCD uses silicon as the main manufacturing material, and pixels are formed through processes such as doping. Due to the influence of wavelength on the photoelectric effect, the quantum effect of ultraviolet light with a shorter wavelength is lower, resulting in a weak response of the CCD to ultraviolet light, and further leading to a more severe PRNU effect of the CCD in the ultraviolet band. Therefore, for a spectrometer including the ultraviolet band, it is very necessary to perform PRNU correction on it.

[0004] The PRNU effect of the CCD is an inherent characteristic of the CCD device itself. Limited by the manufacturing process and materials, it cannot be fundamentally eliminated, and only calibration can be used to correct its PRNU imaging results.

[0005] Currently, the following methods are available for PRNU correction of imaging spectrometers:

[0006] Using the flat-field correction method for the CCD die, that is, using an integrating sphere or a diffuser as the flat-field light source to irradiate the CCD focal plane, and then processing the obtained image data to obtain the PRNU correction coefficient. This method cannot perform PRNU correction for different spectral bands of specific regions of the CCD image plane, that is, spectral channels. Usually, the PRNU differences in different bands of the CCD are relatively large. Therefore, this method is not suitable for PRNU correction of imaging spectrometers;

[0007] For the CCD die, the elliptical spot method is used. By obtaining the ideal spot, an ideal light source is established using the optical radiation model of the spot. The PRNU correction coefficient of the spot region is obtained by processing the actual spot image acquired by the CCD, and then the PRNU correction coefficient of the entire image plane is obtained by displacement. This method can conveniently obtain a monochromatic spot, thereby obtaining the correction coefficients of different regions and different bands on the CCD image plane. Since the establishment process of the ideal radiation model is relatively difficult, especially when the stray light is not well controlled, the fitting result of the radiation model will have a large error, which will affect the reliability of the result. Therefore, the practicability cannot be guaranteed;

[0008] For the imaging spectrometer, the flat-field correction method is used, that is, a halogen tungsten lamp (or xenon lamp, etc.) integrating sphere or diffuser is used as the flat-field light source to irradiate the CCD focal plane, and then the acquired image data is processed to obtain the PRNU correction coefficients of different spectral channels. This method can obtain the PRNU correction coefficients of different regions (spectral channels, usually a column of pixels) on the CCD. By correcting the data of each single band one by one, this method can achieve the PRNU correction of different bands. However, since the number of values in a single band (a column of pixels) is small, and due to the spectral drift of the imaging spectrometer itself during the application process, the correction result of this method may have a large deviation.

[0009] The OPO laser, as a pulsed laser, can provide a monochromatic light source with high resolution and low half-width. However, due to the large deviation in the number and intensity of its pulses within a certain integration time, the imaging spectrometer cannot obtain image data with stable brightness. Therefore, it cannot be used as a flat-field correction light source. As described in the previous section, the existing PRNU correction methods for imaging spectrometers have insufficient correction accuracy in the spectral channels. Summary of the Invention

[0010] A PRNU correction method for a hyperspectral imaging spectrometer proposed by the present invention solves the problem that in the existing PRNU correction methods for imaging spectrometers, precise PRNU correction cannot be performed for different spectral channels, and solves the problem of unstable image brightness caused by using the OPO pulsed laser as a flat-field light source.

[0011] To achieve the above object, the present invention adopts the following technical solutions:

[0012] A PRNU correction method for a hyperspectral imaging spectrometer includes the following steps,

[0013] First, obtain multiple flat-field image data at two brightness levels from the integrating sphere flat-field images of a tungsten-halogen light source, and calculate the standard deviation of the image means at the two brightness levels through statistical methods. Use it as a reference for data screening to obtain images within this reference range from a large dataset of flat-field images of pulsed lasers. For the wavelength bands of the hyperspectral imaging spectrometer, select the laser wavelength, perform decoherence, and then collect and screen the flat-field data. Perform PRNU correction processing on the screened flat-field data of the laser to obtain the correction coefficient. Interpolate the PRNU correction coefficients of different wavelengths to obtain a set of PRNU correction coefficients in the high-resolution wavelength band. Using the PRNU correction coefficients of different bands can achieve high-precision PRNU correction for the data of the hyperspectral imaging spectrometer.

[0014] On the other hand, the present invention also discloses a computer-readable storage medium storing a computer program. When the computer program is executed by a processor, the processor is caused to execute the steps of the above method.

[0015] As can be seen from the above technical solutions, the PRNU correction method for the hyperspectral imaging spectrometer of the present invention can obtain flat-field data with a stability better than that of a stable light source (such as a tungsten-halogen lamp) through a specific experimental device and data processing method, and then use the general two-point method to achieve precise band-related PRNU correction of the detector of the imaging spectrometer. The present invention can achieve PRNU correction of the imaging spectrometer in different spectral channels while ensuring the accuracy of the correction results.

[0016] Specifically, since it is impossible to obtain monochromatic flat-field light sources with high resolution in different bands using light sources such as LEDs and tungsten-halogen lamps; tunable continuous lasers can obtain stable monochromatic lasers in multiple bands, but they are extremely expensive, especially the price of realizing laser tunability and continuous output in the ultraviolet band is high; OPO pulsed lasers can tunably output monochromatic light in various bands and are even cheaper, but since the pulsed laser cannot obtain a stable PRNU correction field, the present invention uses a tungsten-halogen lamp as a stable light source for calibration and combines a data screening method to achieve the acquisition of stable PRNU correction field data for the detector of the imaging spectrometer in various bands, reducing the equipment cost and expanding the application range of pulsed lasers.

[0017] The existing flat-field correction method for imaging spectrometers only performs PRNU correction on a certain spectral channel, and the effective dataset is only a column of pixels in this spectral channel, with a small amount of data. Moreover, the spectral channel changes caused by the drift of the spectrometer will bring additional errors. The present invention uses the bare chip of the imaging focal plane of the imaging spectrometer to perform high-resolution spectral flat-field imaging, and can obtain PRNU correction parameters for the entire image plane of all spectral channels of the spectrometer. The data volume of each spectral channel is larger and the problem of spectral drift does not need to be considered, resulting in higher correction accuracy and better stability. Description of the Drawings

[0018] Figure 1 It is a schematic diagram of the theoretical model of the integral sphere radiance imaging process;

[0019] Figure 2 It is a schematic diagram of the data acquisition system for the implementation of the present invention;

[0020] Figure 3 It is a schematic diagram of the data acquisition process of the method of the embodiment of the present invention. Specific implementation manners

[0021] To make the objectives, technical solutions and advantages of the embodiments of the present invention clearer, the following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are some but not all of the embodiments of the present invention.

[0022] A PRNU correction method for a hyperspectral imaging spectrometer according to an embodiment of the present invention first obtains a plurality of flat-field image data at two brightness levels through the integral sphere flat-field image of a tungsten halogen light source, and calculates the standard deviation of the image means at the two brightness levels through a statistical method, which is used as a reference for data screening, and obtains the images within this reference range from a large number of flat-field image data sets of pulsed lasers; for the bands of the hyperspectral imaging spectrometer, select the laser wavelength and perform flat-field data acquisition and screening after de-coherence, perform PRNU correction processing on the screened laser flat-field data to obtain correction coefficients; perform data interpolation on the PRNU correction coefficients of different wavelengths, so as to obtain a set of PRNU correction coefficients at high-resolution bands. Using the PRNU correction coefficients of different bands can achieve high-precision PRNU correction of the hyperspectral imaging spectrometer data.

[0023] The following is a specific description:

[0024] Theoretical model establishment:

[0025] The imaging process of the imaging spectrometer detector for the integral sphere is the sampling process of the light radiation energy of the integral sphere. The integral sphere radiance image at a certain fixed brightness obtained with a certain integration time is a sampling sample of the total integral sphere radiation brightness within this integration time. The mean distribution of the sampling samples is the sample mean sampling distribution of this total, which should conform to the central limit theorem.

[0026] Within a certain integration time, the energy distribution of the radiance at the light outlet of the integral sphere at a fixed brightness in a unit area can be regarded as a total, and this total follows a certain probability distribution. The total mean is the integral sphere radiance value, which is represented by the pixel gray value here and is set as μ, and the total variance is the square of the integral sphere non-uniformity, which is set as σ 2 . As Figure 1As shown in the figure, the photosensitive area of the detector contains I rows and J columns. The total number of pixels n = I * J, the area of the photosensitive area is S2, and the area of the light outlet of the integrating sphere is S1. Then the sampling sample contains I * J elements in total. Let the number of elements contained in the population be N, then there is:

[0027]

[0028] According to the Central Limit Theorem in mathematical statistics, the expectation of the sample mean is the population mean, and the variance of the sample mean should satisfy the following formula:

[0029]

[0030] Obtained from formula 1-2:

[0031]

[0032] Furthermore, according to the principles of mathematical statistics, when the sample size n is large enough, the sample mean should approach a normal distribution. Combining the imaging process of the integrating sphere radiance, the total number of pixels in the photosensitive area of the detector is usually very large, reaching millions. Therefore, the corresponding sample mean distribution should conform to the normal distribution, and the variance satisfies formula 3. Then the variance of the sample mean is extremely small and can be ignored.

[0033] The signal model of the imaging spectrometer detector is as follows: within a certain integration time, the pixels on the photosensitive surface of the detector collect and photoelectrically convert the part of the radiation energy of the integrating sphere projected onto the pixel area, converting the light energy into an analog voltage signal, and the voltage becomes a grayscale value signal after pre-amplification and analog-to-digital conversion. Due to the existence of circuit noise in this signal model, there is a deviation when the integrating sphere is converted into a grayscale value, that is, circuit noise, denoted as σ E .

[0034] The light radiation model of the integrating sphere is: the power supply drives a light source such as a tungsten halogen lamp to emit light, and the light source forms a uniform luminance surface light source with the size of the opening area through multiple diffuse reflections inside the integrating sphere. Due to the instability of the power supply, there is instability in the light emission process. Denote the instability of the light source within the integration time as σ L .

[0035] The deviations and instabilities in the signal model of the imaging spectrometer detector and the light radiation model of the integrating sphere lead to the instability of the sampling results, and both conform to the normal distribution. Therefore, the theoretical model of the integrating sphere radiance imaging process is the sampling distribution of the sample mean that conforms to the normal distribution, with an expectation of the population mean μ and a variance of

[0036]

[0037] When n is large enough (n > 30), Equation 4 becomes:

[0038]

[0039] The method includes a Figure 2 data acquisition system as shown

[0040] The system includes: an OPO laser, a coherence eliminator, a tungsten halogen lamp drive power supply and a tungsten halogen lamp, an integrating sphere, an imaging spectrometer detector, and a control computer. Among them, the OPO laser generates high-resolution monochromatic light of different bands. Theoretically, the bands should cover the working bands of the imaging spectrometer. Usually, the OPO laser can generate monochromatic light with a resolution of 1 nm. The coherence eliminator is used to decohere the laser and eliminate the influence of laser speckle; the integrating sphere receives the monochromatic light of the laser or the light of the tungsten halogen lamp through the light inlet, and after homogenization, outputs uniform light with a specific irradiance value through the light outlet; the imaging spectrometer detector collects the irradiance energy of the integrating sphere through the pixel of the photosensitive area and converts it into pixel gray values; the control computer controls the OPO laser and the imaging spectrometer detector to achieve light source band control, irradiance control, and data acquisition.

[0041] Data acquisition:

[0042] According to the theoretical model of the integrating sphere irradiance imaging process, it can be known that the variance of the sampling result of the sample mean is the light source instability σ within the integration time, and this value is related to the test environment and equipment. Therefore, the commonly used detector PRNU correction method - tungsten halogen lamp flat-field correction method will be used first to obtain the measured data for determining the light source instability σ brought by the test environment and equipment; secondly, different band monochromatic lights of the OPO laser are used as the light source of the integrating sphere to obtain more data, and the samples with deviations less than are used as the data set for further PRNU correction. The specific method is as follows.

[0043] The band selection of the OPO laser refers to the working band of the imaging spectrometer. Assume the wavelength distribution λ′ in the spectral dimension of the detector:

[0044] λ′ = [λ′1 λ′2 … λ′ K (Equation 4) The band selection of the OPO laser is λ:

[0045] λ = [λ1 λ2 … λ L (Equation 5) Then there should be λ1 < ′1, λ L > ′ K , and usually K > L for a high-resolution imaging spectrometer.

[0046] The data acquisition process of the method is asFigure 3 as shown

[0047] The data acquisition steps are as follows:

[0048] 101) Turn on the halogen tungsten lamp drive power supply until it is stable;

[0049] 102) Adjust the output energy of the halogen tungsten lamp so that the image brightness is P1;

[0050] 103) Collect N image data and calculate the average value of the gray values of the effective pixels in each image. N should be as large as possible, and it can be set that N > 500;

[0051] 104) Adjust the image brightness to P2 and repeat step 103);

[0052] 105) Calculate the standard deviations σ1 and σ2 of the N average values at the two brightness levels respectively;

[0053] 106) Turn on the OPO laser and preheat to ensure that the equipment is in good condition;

[0054] 107) Adjust the output wavelength of the laser to λ1;

[0055] 108) Adjust the output energy of the laser so that the image brightness is P1;

[0056] 109) Collect N' image data, and N' should be greater than 2N, that is, N' > 1000;

[0057] 110) Adjust the image brightness to P2 and repeat step 109);

[0058] 111) Adjust the output wavelength of the laser to λ2~λ L , and repeat steps 108) to 110).

[0059] Data processing:

[0060] Process the acquired data.

[0061] The specific steps are as follows:

[0062] 201) Select the laser light source image data set with a wavelength of λ1 and a brightness of P1;

[0063] 202) Calculate the pixel average value of the effective pixel area in N ’ images, denoted as V q , (q = 1, 2,..., N ’ );

[0064] 203) Calculate the median V q in V q-half , and select the one among them that is in [V q-half , Vq-half The image data of [+σ1] is used as a calibration data set with a wavelength of λ1 and a brightness of P1, denoted as S(λ1, P1);

[0065] 204) Select the laser source image data set with a wavelength of λ1 and a brightness of P2;

[0066] 205) Calculate N ’ The pixel average value of the effective pixel area in the N q images, denoted as V ’ ′, (q = 1, 2, …, N

[0067] 206) Calculate the median V q in V q ′ -half , and select the image data within [V q ′ -half , V q ′ -half +σ2] as the calibration data set with a wavelength of λ1 and a brightness of P2, denoted as S(λ1, P2);

[0068] 207) Use the PRNU two-point calibration method (this method is a general method) for the data sets S(λ1, P1) and S(λ1, P2) to obtain the calibration parameters λ 1- α i,j and λ 1- β i,j (i, j represent the pixels in the i-th row and j-th column);

[0069] 208) Select wavelengths λ2 to λ L , and repeat the above steps to obtain the calibration parameters λ L at wavelengths λ2 to λ t- α i,j , λ t- β i,j (t = 2, 3, …, L);

[0070] 209) Use an interpolation algorithm (such as but not limited to spline interpolation, polynomial fitting, etc.) to calculate the PRNU calibration parameters for all spectral channels of the detector and

[0071] After obtaining the calibration coefficients through the above steps, the PRNU calibration can be performed on different channels of the imaging spectrometer:

[0072]

[0073] Among them, is the calibrated value of the pixel in the i-th row and j-th column of the spectral channel with wavelength u, V u-i,jis the actually acquired pixel gray value.

[0074] An embodiment of the present invention proposes a theoretical model for the imaging process of an imaging spectrometer for the irradiance of an integrating sphere; a dual-light-source data acquisition system based on the above theoretical model is proposed. The tungsten halogen light source is used to obtain the PRNU correction data set interval, and the OPO laser light source is used to obtain the flat-field correction data set of the high-resolution spectral channel; generally speaking, the present invention proposes a data processing method to solve the problem of unstable imaging caused by the OPO laser as a pulsed light source, and extracts a correction data set that can be better than the flat-field image of a stable light source; at the same time, a method of spline interpolation processing for the band correction coefficient of the OPO laser is proposed to obtain the PRNU correction coefficient of each spectral band of the imaging spectrometer.

[0075] On the other hand, the present invention also discloses a computer-readable storage medium storing a computer program, which when executed by a processor causes the processor to execute the steps of any of the above methods.

[0076] On yet another aspect, the present invention also discloses a computer device including a memory and a processor, the memory storing a computer program, which when executed by the processor causes the processor to execute the steps of any of the above methods.

[0077] In another embodiment provided by the present application, a computer program product containing instructions is also provided, which when running on a computer causes the computer to execute the steps of any of the above embodiments.

[0078] It can be understood that the system provided by the embodiment of the present invention corresponds to the method provided by the embodiment of the present invention. For the explanations, examples and beneficial effects of related content, reference can be made to the corresponding parts in the above method.

[0079] Those of ordinary skill in the art can understand that all or part of the processes in the methods of the above embodiments can be completed by instructing relevant hardware through a computer program. The program can be stored in a non-volatile computer-readable storage medium. When the program is executed, it can include the processes of the embodiments of the above methods. Among them, any reference to a memory, storage, database, or other medium used in the embodiments provided in the present application can include non-volatile and / or volatile memories. Non-volatile memories can include read-only memory (ROM), programmable ROM (PROM), electrically programmable ROM (EPROM), electrically erasable programmable ROM (EEPROM), or flash memory. Volatile memories can include random access memory (RAM) or external cache memory. By way of illustration and not limitation, RAM is available in various forms, such as static RAM (SRAM), dynamic RAM (DRAM), synchronous DRAM (SDRAM), double data rate SDRAM (DDR SDRAM), enhanced SDRAM (ESDRAM), synchronous link DRAM (SLDRAM), Rambus direct RAM (RDRAM), direct memory bus dynamic RAM (DRDRAM), and Rambus dynamic RAM (RDRAM), etc.

[0080] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as the scope recorded in this specification.

[0081] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions recorded in the foregoing embodiments, or perform equivalent replacements on some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for PRNU correction of a hyperspectral imaging spectrometer, including data acquisition and data processing, characterized in that, The data acquisition includes obtaining multiple flat-field image data at two brightness levels through the integrating sphere flat-field image of a tungsten halogen light source, calculating the standard deviation of the image means at the two brightness levels by statistical methods, using it as a reference for data screening, and obtaining the images within this reference range from a set of pulsed laser flat-field image data; The data processing includes selecting the laser wavelength and de-cohering it for flat-field data acquisition and screening for the bands of the hyperspectral imaging spectrometer, performing PRNU correction processing on the screened laser flat-field data to obtain correction coefficients; performing data interpolation on the PRNU correction coefficients of different wavelengths to obtain a set of PRNU correction coefficients at high-resolution bands; using the PRNU correction coefficients of different bands can achieve high-precision PRNU correction of the hyperspectral imaging spectrometer data; The data acquisition includes: The wavelength band selection of the OPO laser refers to the working wavelength band of the imaging spectrometer; assuming the wavelength distribution in the spectral dimension of the detector : The wavelength band selection of the OPO laser is There should be and , for high-resolution imaging spectrometers, usually K > L; Then the data acquisition steps are as follows: 101) Turn on the tungsten halogen lamp drive power supply until it is stable; 102) Adjust the output energy of the tungsten halogen lamp so that the image brightness is P1; 103) Collect N image data and calculate the average value of the gray values of the effective pixels of each image, assuming N > 500; 104) Adjust the image brightness to P2 and repeat step 103); 105) Calculate the standard deviations σ1 and σ2 of the N average values at the two brightness levels respectively; 106) Turn on the OPO laser and preheat to ensure that the device is in good condition; 107) Adjust the output wavelength of the laser to ; 108) Adjust the output energy of the laser so that the image brightness is P1; 109) Collect N' image data, where N' is greater than 2N, that is, N' > 1000; 110) Adjust the image brightness to P2 and repeat step 109); 111) Adjust the output wavelength of the laser to , and repeat steps 108) to 110); The data processing steps include, Select a laser light source image data set with a wavelength of and a brightness of P1; 202) Calculate N ’ The pixel average value of the effective pixel region in the q image is denoted as V, where q = 1, 2, …, N ’ ; 203) Calculate V q The median value V in q-half , and select the image data among them that is in [V q-half , V q-half +σ1] as the calibration data set with a wavelength of , a brightness of P1, denoted as S(λ1, P1); Select a laser light source image data set with a wavelength of and a brightness of P2; 205) Calculate N ’ The pixel average value of the effective pixel area in the image is denoted as ’ , where q = 1, 2, …, N 206) Calculate the median value in , and select the one that is in , +σ2] of the image data as the calibration data set with a wavelength of and a brightness of P2, denoted as S(λ1, P2); 207) Use the PRNU two-point correction method for the data sets S(λ1,P1) and S(λ1,P2) to obtain the correction parameters λ at the wavelength 1- α i,j and λ 1- β i,j , where i and j represent the pixels in the i-th row and j-th column; 208) Select the wavelength , repeat the above steps to obtain the calibration parameter λ at the wavelength t- α i,j , λ t- β i,j , where t = 2, 3, …, L; 209) Calculate the PRNU correction parameters for all spectral channels of the detector using the interpolation algorithm and , u = 1, 2, …, K; After obtaining the correction coefficients through the above steps, PRNU correction can be performed on different channels of the imaging spectrometer: Among them, is the corrected value of the pixel at the i-th row and j-th column with the spectral channel at wavelength u, is the actually obtained pixel gray value.

2. The PRNU correction method for the hyperspectral imaging spectrometer according to claim 1, wherein: The data acquisition, where the data acquisition system includes: OPO laser, coherence eliminator, tungsten halogen lamp drive power supply and tungsten halogen lamp, integrating sphere, imaging spectrometer detector and control computer; among them, the OPO laser generates high-resolution monochromatic light of different bands, and the bands should cover the working bands of the imaging spectrometer. The OPO laser can generate monochromatic light with a resolution of 1 nm. The coherence eliminator is used to de-cohere the laser and eliminate the influence of laser speckles. The coherence eliminator is used to de-cohere the laser and eliminate the influence of laser speckles; The integrating sphere receives the laser monochromatic light or tungsten halogen light through the light inlet, and after homogenization, outputs uniform light with a specific radiance value through the light outlet; The imaging spectrometer detector collects the radiance energy of the integrating sphere through the pixel of the photosensitive area and converts it into pixel gray values; The control computer controls the OPO laser and the imaging spectrometer detector to achieve light source band control, radiance control and data acquisition.

3. A computer-readable storage medium storing a computer program, which when executed by a processor causes the processor to execute the steps of the method according to claim 1 or 2.

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