A shutterless non-uniformity correction method and system

Abstract

The application relates to a shutterless non-uniformity correction method and system, which comprises the following steps: obtaining a starting bias parameter of a background image according to an infrared detector end background image and an infrared lens end background image; obtaining a gain bias parameter of the background image according to a change amount of infrared image data output by the infrared detector when the infrared imaging device changes from a cold state to a thermal equilibrium state; determining residual non-uniformity of a current background image obtained by the infrared detector of the infrared imaging device during the process of the infrared imaging device changing from the cold state to the thermal equilibrium state, and obtaining a process bias parameter of the background image according to the change amount of the residual non-uniformity; and performing non-uniformity correction on a current infrared image. The application can decompose the correction of the non-uniformity background image into the starting bias parameter, the gain bias parameter and the process bias parameter, calculate an ideal background image of the non-uniformity correction, and realize the non-uniformity correction of the infrared image under the shutterless correction condition.

Description

Technical Field

[0001] This invention relates to the field of infrared imaging technology, and in particular to a shutterless non-uniformity correction method and system. Background Technology

[0002] Because the response characteristics of each detection unit in an uncooled infrared detector exhibit varying non-uniformity, this non-uniformity degrades the imaging quality of the infrared imaging system. Currently, a common method for non-uniformity correction is to add a built-in shutter to the system and perform periodic occlusion correction. However, the addition of a shutter increases the complexity of the detector's mechanical structure, limits its miniaturization, and increases costs. Furthermore, the shutter correction process interrupts image input, affecting the system's external observation and real-time target tracking.

[0003] Therefore, existing technologies have developed non-uniform correction methods for infrared images without shutter speed, including: 1. Calibration-based non-uniform correction methods, which establish a relationship model between the detector's working state and response to obtain different offline background images, and then select a matching background image according to the actual working state to perform non-uniform correction on the infrared image. However, in this technical solution, the relationship model is difficult to obtain, and the response coefficients in the relationship model will drift over time, resulting in poor correction effect; 2. Scene-based non-uniform correction methods, which separate non-uniform noise and useful image information by statistically analyzing scene characteristics, learn to obtain a real-time corrected background image, and then use the real-time corrected background image to perform non-uniform correction on the infrared image. This technical solution has a large computational load, slow convergence speed, and many limitations when used, such as requiring hardware support such as gyroscopes or accelerometers, and it depends on moving scenes, with poor image correction effect in static scenes. Summary of the Invention

[0004] The purpose of this invention is to provide a shutterless non-uniformity correction method and system, which can decompose the correction of the non-uniform background image acquired by the infrared detector into initial bias parameters, gain bias parameters and process bias parameters, so as to calculate the ideal background image for non-uniformity correction in real time and automatically, so as to realize the non-uniformity correction of infrared images under shutterless correction conditions.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] On the one hand, a shutterless non-uniformity correction method is provided, which includes the following steps:

[0007] The initial bias parameters of the background image are obtained based on the background image at the infrared detector end and the background image at the infrared lens end.

[0008] The gain bias parameters of the background image are obtained by measuring the change in infrared image data output by the infrared detector when the infrared imaging device changes from a cold state to a thermal equilibrium state.

[0009] The residual non-uniformity of the current background image acquired by the infrared detector of the infrared imaging device is determined during the process of the infrared imaging device from the cold state to the thermal equilibrium state, and the process bias parameter of the background image is obtained based on the change of the residual non-uniformity.

[0010] Non-uniformity correction is performed on the current infrared image based on the initial bias parameter, gain bias parameter, and process bias parameter.

[0011] Preferably, the initial offset parameter offset1 of the background image is obtained according to the following formula:

[0012] offset1=coef 1i (Y16) 1i -Y16 2i )

[0013] Among them, coef 1i Y16 is the gain coefficient. 1i Y16 2i These are the corrected background images of the infrared detector and the corrected background image of the infrared lens, respectively.

[0014] Preferably, the corrected infrared detector background image Y16 1i Base1 image from infrared detector i The low-frequency characteristics are obtained based on two-point correction;

[0015] Corrected infrared lens background image Y16 2i Base2 image from infrared lens i The low-frequency characteristics are obtained based on two-point correction.

[0016] Preferably, the corrected infrared detector background image Y16 is obtained using the following formula. 1i Infrared lens background image Y16 2i :

[0017] Y16 1i =k X16 1i -Base1 i_m

[0018] Y16 2i =k X16 2i -Base2 i_m

[0019] Where k is the gain coefficient for two-point correction of the infrared image; X16 1i Base1 is the background image at the infrared detector end before two-point correction. i Raw infrared image data; X16 2i Base2 image of the infrared lens before two-point correction. i Raw infrared image data; Base1 i_m Base2 i_m Base1, representing the background image at the infrared detector end. i Low-frequency characteristics, infrared lens background image Base2 i Its low-frequency characteristics.

[0020] Preferably, the gain bias parameter offset2 of the background image is obtained according to the following formula:

[0021]

[0022] Among them, coef T1 Δb is the multiplicative coefficient related to the focal plane temperature of the infrared detector in the infrared imaging device; Δb is the change in infrared image data output by the infrared detector when the infrared imaging device changes from a cold state to a thermal equilibrium state, and Δb = X16 T1 -X16 T2 X16 T1 X16 represents the infrared image data output by the infrared detector when the infrared imaging equipment is in a cold state. T2 Δb represents the infrared image data output by the infrared detector when the infrared imaging device is in thermal equilibrium; T1 represents the change in focal temperature corresponding to Δb.

[0023] Preferably, the residual non-uniformity Y16c of the current background image is obtained according to the following formula:

[0024] Y16c=k X16-Base-offset1-k offset2

[0025] Where k is the gain coefficient when performing two-point correction on the infrared image; Base is the current background image acquired by the infrared detector of the infrared imaging device during the process of the infrared imaging device changing from a cold state to a thermal equilibrium state; X16 is the original infrared image data output by the infrared detector of the infrared imaging device before performing two-point correction; offset1 and offset2 are the initial offset parameter and gain offset parameter, respectively.

[0026] Preferably, the process bias parameters for obtaining the background image based on the change in residual non-uniformity include the following steps:

[0027] The residual non-uniformity change of the background image is obtained during the process of the infrared imaging device changing from a cold state to a thermal equilibrium state, and this is used as the process bias template M. rn ;

[0028] The process bias parameter offset3 is obtained using the following formula:

[0029] offset3=coef3 M rn

[0030] Where coef3 is the process bias adaptive coefficient.

[0031] Preferably, obtaining the process bias adaptive coefficient coef3 includes the following steps:

[0032] Obtaining the process bias template M rn The average pixel value and the center pixel value of the entire image;

[0033] Process bias template M rn The pixel value of each pixel in the image is subtracted from the center pixel value of the entire image to obtain the offset-free template image;

[0034] The offset-free template image is divided into blocks;

[0035] The variance between the current background image and the offset template image blocks is obtained using the following formula:

[0036]

[0037] Among them, IMG Ni Y16c represents the current residual non-uniformity of the background image; D represents the variance.

[0038] Furthermore, the coefficient coef3 corresponding to the minimum value of function f can be obtained using the following formula:

[0039] .

[0040] Preferably, non-uniformity correction is performed according to the following formula:

[0041] NUC = Y16c - offset3 = k X160-Base0-offset1-k offset2-offset3

[0042] Wherein, NUC is the infrared image after non-uniformity correction; k is the gain coefficient when performing two-point correction on the infrared image; Base0 is the current background image; X160 is the raw infrared image data output by the infrared detector of the infrared imaging device before two-point correction; offset1, offset2, and offset3 are the initial offset parameter, gain offset parameter, and process offset parameter, respectively.

[0043] On the other hand, a shutterless non-uniformity correction system is also provided, which includes:

[0044] The initial bias parameter acquisition unit is used to acquire the initial bias parameters of the background image.

[0045] The gain bias parameter acquisition unit is used to acquire the gain bias parameter of the background image based on the change in infrared image data output by the infrared detector when the infrared imaging device changes from a cold state to a thermal equilibrium state.

[0046] The residual non-uniformity acquisition unit is used to determine the residual non-uniformity of the current background image acquired by the infrared detector of the infrared imaging device during the process of the infrared imaging device changing from a cold state to a thermal equilibrium state.

[0047] The process bias parameter acquisition unit is used to acquire the process bias parameters of the background image based on the residual non-uniformity change of the background image during the process of the infrared imaging device from the cold state to the thermal equilibrium state.

[0048] The image correction unit is used to perform non-uniformity correction on the current infrared image based on the initial bias parameter, gain bias parameter, and process bias parameter.

[0049] In summary, the present invention has the following advantages compared with the prior art:

[0050] The present invention has the following advantages:

[0051] This invention decomposes the correction of non-uniform background images acquired by infrared detectors into initial bias parameters, gain bias parameters, and process bias parameters, so as to calculate the ideal background image for non-uniform correction in real time and automatically. It further realizes the non-uniform correction of infrared images without shutter correction. It solves the problems of poor correction effect caused by response coefficient drift and excessive dependence on scene and hardware in scene-based non-uniform correction methods. Attached Figure Description

[0052] Figure 1 This is a flowchart of the shutterless non-uniformity correction method of the present invention;

[0053] Figure 2 Infrared images before and after processing by the correction method of this invention;

[0054] Figure 3 This is a schematic diagram of the shutterless non-uniformity correction system of the present invention. Detailed Implementation

[0055] 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. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0056] Example 1

[0057] like Figure 1 As shown, this embodiment provides a shutterless non-uniformity correction method, which is applicable to uncooled infrared imaging devices. Specifically, the shutterless non-uniformity correction method includes the following steps:

[0058] S1. The background image is directly acquired through the infrared detector of the infrared imaging device, and the background image is also acquired through the optical components of the same infrared imaging device, which consist of an infrared lens and an infrared detector. The initial offset parameter offset1 of the background image is also acquired. The initial offset parameter offset1 is the difference offset between the thermal radiation outside the lens and the thermal radiation inside the lens of the infrared imaging device. In this embodiment, the infrared imaging device includes an uncooled infrared thermal imager. Acquiring the background image directly through the infrared detector of the infrared imaging device means that the infrared detector directly senses the light from an external object (such as a blackbody) and thereby acquires an infrared image, and determines the background image based on the infrared image. Acquiring the background image through the optical components of the same infrared imaging device, which consist of an infrared lens and an infrared detector, means that the light from an external object first passes through the infrared lens and is then sensed by the infrared detector, thereby acquiring an infrared image, and determining the background image based on the infrared image.

[0059] Specifically, step S1 includes the following steps:

[0060] Under the same ambient temperature, infrared images of blackbodies at the same temperature (such as blackbodies t1, t2, and t3) are directly acquired by the infrared detector of an infrared imaging device, and the background image Base1 at the infrared detector end is determined based on the infrared image. i ;

[0061] Under the same ambient temperature, infrared images of blackbodies at the same temperature (such as blackbodies t1, t2, and t3) are acquired using the same infrared imaging equipment and an optical assembly consisting of an infrared lens and an infrared detector. Based on these infrared images, the background image Base2 at the infrared lens end is determined. i; Base1 image of the infrared detector end i Infrared lens background image Base2 i All are infrared images;

[0062] Base1 of the infrared detector end i Infrared lens background image Base2 i All values ​​were normalized to zero using the mean or center value.

[0063] Base1, the background image of the infrared detector end after mean or center value zeroing processing i Infrared lens background image Base2 i Low-frequency feature extraction was performed on all samples, and the background image Base1 from the infrared detector was used as the basis for the extraction. i The low-frequency features extracted are used as the first background image correction parameter Base1. i_m And the Base2 image from the infrared camera. i The low-frequency features extracted are used as the second background image correction parameter Base2. i_m Furthermore, the extraction of low-frequency features can be achieved using methods such as mean filtering, median filtering, and Gaussian filtering. For example, in this embodiment, 5 5. Gaussian filtering (sigma=5) is used to extract low-frequency features;

[0064] Correction parameter Base1 based on the first background image i_m Base1 of the infrared detector end i Two-point calibration is performed to obtain the calibrated infrared detector background image Y16. 1i ; and, by correcting the Base2 parameter through the second background image. i_m Base2 image of infrared lens end i Two-point correction is performed to obtain the corrected infrared lens background image Y16. 2i For example, in this embodiment, the corrected infrared detector background image Y16 can be obtained through formulas (1)-(2). 1i Infrared lens background image Y16 2i :

[0065] Y16 1i =k X16 1i -Base1 i_m (1)

[0066] Y16 2i =k X16 2i -Base2 i_m (2)

[0067] Where k is the gain coefficient for two-point correction of the infrared image, and its value ranges from [0.8-1.2]; X16 1i Base1 is the background image at the infrared detector end before two-point correction. i Raw infrared image data; X16 2i Base2 image of the infrared lens before two-point correction. i The original infrared image data;

[0068] The initial offset parameter offset1 of the background image is obtained according to formula (3):

[0069] offset1=coef 1i (Y16) 1i -Y16 2i (3)

[0070] Among them, coef 1i The gain coefficient can be determined based on the background image Base1 at the infrared detector. i Infrared lens background image Base2 i relative to the blackbody temperature T i The change in the data is obtained through least squares fitting. The specific process includes: determining the best function match for the data by calculating the sum of squared errors to minimize the sum of squared errors between the obtained data and the actual data; the smaller the mean square error, the better the fitting effect; and fitting the first background image correction parameters Base1. i_m Base2, the second background image correction parameter i_m The difference between the blackbody temperature T and the blackbody temperature T i The relationship was further used to calculate the corresponding blackbody temperature T. i Gain coefficient under 1i ;

[0071] S2. Obtain the gain bias parameter offset2 of the background image based on the change in infrared image data output by the infrared detector when the infrared imaging device changes from a cold state to a thermal equilibrium state. The gain bias parameter offset2 of the background image refers to the process non-uniformity of the infrared detector response caused by the increase in internal temperature of the infrared imaging device after the infrared imaging device is powered on and the burn-in time increases.

[0072] Specifically, in step S2, the gain bias parameter offset2 of the background image is obtained in real time according to formula (4):

[0073] (4)

[0074] Among them, coef T1 This is a multiplicative coefficient related to the focal plane temperature of the infrared detector in the infrared imaging device. It can be a first-order, second-order, or higher-order function of the focal plane temperature, as in this embodiment. a1, a2, a3...a n-1 Both are focal temperature coefficients, where n is the highest power of a multinomial function, determined according to a defined power-law fitting method; Δb is the change in infrared image data output by the infrared detector when the infrared imaging device transitions from a cold state to a thermal equilibrium state, and Δb = X16. T1 -X16 T2 X16 T1 X16 represents the infrared image data output by the infrared detector when the infrared imaging equipment is in a cold state. T2 This refers to the infrared image data output by the infrared detector when the infrared imaging device is in thermal equilibrium, and X16 T1 X16 T2 All data are infrared images before two-point correction; T1 represents the focal temperature change corresponding to Δb.

[0075] S3. Determine the residual non-uniformity Y16c of the current background image acquired by the infrared detector of the infrared imaging device during the process of the infrared imaging device from the cold state to the thermal equilibrium state. The residual non-uniformity Y16c refers to the residual infrared image non-uniformity after the current background image has undergone non-uniformity correction processing such as two-point correction in step S1.

[0076] Specifically, step S3 obtains the residual non-uniformity Y16c of the current background image in real time according to formula (5):

[0077] Y16c=k X16-Base-offset1-k offset2 (5)

[0078] Where k is the gain coefficient when performing two-point correction on the infrared image, and its value ranges from [0.8 to 1.2]; Base is the current background image acquired by the infrared detector of the infrared imaging device during the process of the infrared imaging device going from a cold state to a thermal equilibrium state; X16 is the original infrared image data output by the infrared detector of the infrared imaging device before performing two-point correction.

[0079] S4. Obtain the process offset parameter offset3 of the background image based on the residual non-uniformity change of the background image during the process of the infrared imaging device from the cold state to the thermal equilibrium state.

[0080] Specifically, step S4 includes the following steps:

[0081] The residual non-uniformity change of the background image is obtained during the process of the infrared imaging device transitioning from a cold state to a thermal equilibrium state, and this change is used as the process bias template M. rn ;

[0082] Obtain the process bias parameter offset3 according to formula (5):

[0083] offset3=coef3 M rn (6)

[0084] Wherein, coef3 is the process bias adaptive coefficient, and its value range is [-2,2].

[0085] Furthermore, obtaining the process bias adaptive coefficient coef3 includes the following steps:

[0086] Obtaining the process bias template M rn The average pixel value and the center pixel value of the entire image;

[0087] Process bias template M rn The pixel value of each pixel in the image is subtracted from the center pixel value of the entire image to obtain the offset-free template image;

[0088] The offset-free template image is divided into blocks. For example, in this embodiment, the offset-free template image is divided into 2 blocks. n There are 4 blocks, where n is an even number greater than or equal to 4, such as n=6, etc.

[0089] The variance between the blocks of the current background image and the offset template image is obtained according to formula (7):

[0090] (7)

[0091] Among them, IMG Ni Y16c represents the current residual non-uniformity of the background image; D represents the variance.

[0092] Furthermore, according to formula (8), the coefficient coef3 corresponding to the minimum value of function f is obtained, and this coefficient coef3 is used to calculate the process bias parameter offset3:

[0093] (8)

[0094] Where E represents the expected value;

[0095] And S5, based on the initial bias parameter offset1, gain bias parameter offset2, and process bias parameter offset3, performs non-uniformity correction on the current infrared image, and finally obtains the non-uniformity corrected infrared image under shutter-free conditions;

[0096] Specifically, in step S4, non-uniformity correction is performed according to formula (9):

[0097] NUC = Y16c - offset3 = k X160-Base0-offset1-k offset2-offset3 (9)

[0098] Wherein, NUC is the infrared image after non-uniformity correction; k is the gain coefficient when performing two-point correction on the infrared image, with a value range of [0.8-1.2]; Base0 is the current background image, which can be the default background image after the infrared imaging device is powered on. This background image can be obtained by acquiring a blackbody or a built-in reference uniform surface image after the infrared imaging device is powered on; X160 is the raw infrared image data output by the infrared detector of the infrared imaging device before two-point correction.

[0099] In the non-uniformity correction method of this embodiment, the correction of the non-uniform background image acquired by the infrared detector is decomposed into obtaining three different bias parameters: initial bias parameter, gain bias parameter, and process bias parameter, so as to calculate the ideal background image for non-uniformity correction in real time and automatically. This further realizes the non-uniformity correction of infrared images without shutter correction. It solves the problems of poor correction effect caused by response coefficient drift and the excessive dependence on scene and hardware in scene-based non-uniformity correction methods. The whole process has low algorithm complexity and low computational load.

[0100] Figure 1 Part (a) shows an uncorrected infrared image taken half an hour after the infrared imaging device was powered on. Figure 1 Part (b) is the infrared image after being processed by the non-uniformity correction method in this embodiment. It can be seen that the non-uniformity of the infrared image has been effectively corrected and the image quality has been significantly improved.

[0101] Example 2:

[0102] This embodiment provides a shutterless non-uniformity correction system, which can implement the shutterless non-uniformity correction method described in Embodiment 1, such as... Figure 3 As shown, the shutterless non-uniformity correction system includes:

[0103] The infrared detector-end background image acquisition unit 1 is used to determine the infrared detector-end background image Base1 based on the infrared images of blackbodies at the same temperature (such as blackbodies t1, t2, and t3) directly acquired by the infrared detector of the infrared imaging device under the same ambient temperature. i ;

[0104] The infrared lens-end background image acquisition unit 2 is used to determine the infrared lens-end background image Base2 based on the infrared images of blackbodies at the same temperature (such as blackbodies t1, t2, and t3, etc.) acquired by the optical components consisting of an infrared lens and an infrared detector of the same infrared imaging device at the same ambient temperature. i ;

[0105] Feature extraction unit 3 is used to extract the background image Base1 from the infrared detector end after mean or center value zeroing. i Infrared lens background image Base2 i Low-frequency feature extraction was performed on all samples, including the background image Base1 from the infrared detector. i The low-frequency features extracted are used as the first background image correction parameter Base1. i_m Base2 image from infrared camera i The low-frequency features extracted are used as the second background image correction parameter Base2. i_m ;

[0106] Two-point correction unit 4, which is used to correct parameter Base1 using the first background image. i_m Base1 of the infrared detector end i Two-point calibration is performed to obtain the calibrated infrared detector background image Y16. 1i ; and, by correcting the Base2 parameter through the second background image. i_m Base2 image of infrared lens end i Two-point correction is performed to obtain the corrected infrared lens background image Y16. 2i The specific process is the same as step S1.

[0107] The initial offset parameter acquisition unit 5 is used to obtain the initial offset parameter offset1 of the background image according to formula (3);

[0108] The gain bias parameter acquisition unit 6 is used to acquire the gain bias parameter offset2 of the background image based on the change in infrared image data output by the infrared detector when the infrared imaging device changes from a cold state to a thermal equilibrium state; its specific process is the same as step S2.

[0109] The residual non-uniformity acquisition unit 7 is used to determine the residual non-uniformity Y16c of the current background image acquired by the infrared detector of the infrared imaging device during the process of the infrared imaging device changing from a cold state to a thermal equilibrium state; its specific process is the same as step S3.

[0110] The process offset parameter acquisition unit 8 is used to acquire the process offset parameter offset3 of the background image based on the residual non-uniformity change of the background image during the process of the infrared imaging device from the cold state to the thermal equilibrium state; its specific process is the same as step S4.

[0111] Image correction unit 9 is used to perform non-uniformity correction on the current infrared image according to the initial bias parameter offset1, the gain bias parameter offset2, and the process bias parameter offset3, and finally obtain the non-uniformity corrected infrared image under shutter-free conditions; its specific process is the same as step S5.

[0112] In summary, this application decomposes the correction of non-uniform background images acquired by infrared detectors into initial bias parameters, gain bias parameters, and process bias parameters, so as to calculate the ideal background image for non-uniform correction in real time and automatically. This further realizes the non-uniform correction of infrared images without shutter correction, which solves the problems of poor correction effect caused by response coefficient drift and the excessive dependence on scene and hardware in scene-based non-uniform correction methods.

[0113] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A shutterless non-uniformity correction method, characterized in that, Includes the following steps: The initial bias parameters of the background image are obtained based on the background image at the infrared detector end and the background image at the infrared lens end. The gain bias parameters of the background image are obtained by measuring the change in infrared image data output by the infrared detector when the infrared imaging device changes from a cold state to a thermal equilibrium state. The residual non-uniformity of the current background image acquired by the infrared detector of the infrared imaging device is determined during the process of the infrared imaging device from the cold state to the thermal equilibrium state, and the process bias parameter of the background image is obtained based on the change of the residual non-uniformity. Furthermore, non-uniformity correction is performed according to the following formula: NUC=Y16c-offset3=k X160-Base0-offset1-k offset2-offset3; Wherein, NUC is the infrared image after non-uniformity correction; k is the gain coefficient when performing two-point correction on the infrared image; Base0 is the current background image; X160 is the raw infrared image data output by the infrared detector of the infrared imaging device before two-point correction; offset1, offset2, and offset3 are the initial offset parameter, gain offset parameter, and process offset parameter, respectively.

2. The shutterless non-uniformity correction method as described in claim 1, characterized in that, The initial offset parameter offset1 of the background image is obtained using the following formula: offset1=coef 1i (Y16 1i -Y16 2i ); Among them, coef 1i Y16 is the gain coefficient. 1i Y16 2i These are the corrected background images of the infrared detector and the corrected background image of the infrared lens, respectively.

3. The shutterless non-uniformity correction method as described in claim 2, characterized in that, Corrected infrared detector background image Y16 1i Base1 image from infrared detector i The low-frequency characteristics are obtained based on two-point correction; Corrected infrared lens background image Y16 2i Base2 image from infrared lens i The low-frequency characteristics are obtained based on two-point correction.

4. The shutterless non-uniformity correction method as described in claim 3, characterized in that, The corrected infrared detector background image Y16 is obtained using the following formula. 1i Infrared lens background image Y16 2i : Y16 1i =k X16 1i -Base1 i_m ; Y16 2i =k X16 2i -Base2 i_m ; Where k is the gain coefficient for two-point correction of the infrared image; X16 1i Base1 is the background image at the infrared detector end before two-point correction. i Raw infrared image data; X16 2i Base2 image of the infrared lens before two-point correction. i Raw infrared image data; Base1 i_m Base2 i_m Base1, representing the background image at the infrared detector end. i Low-frequency characteristics, infrared lens background image Base2 i Its low-frequency characteristics.

5. The shutterless non-uniformity correction method as described in claim 1, characterized in that, The gain bias parameter offset2 of the background image is obtained using the following formula: ； Among them, coef T1 Δb is the multiplicative coefficient related to the focal plane temperature of the infrared detector in the infrared imaging device; Δb is the change in infrared image data output by the infrared detector when the infrared imaging device changes from a cold state to a thermal equilibrium state, and Δb = X16 T1 -X16 T2 X16 T1 X16 represents the infrared image data output by the infrared detector when the infrared imaging equipment is in a cold state. T2 Δb represents the infrared image data output by the infrared detector when the infrared imaging device is in thermal equilibrium; T1 represents the change in focal temperature corresponding to Δb.

6. The shutterless non-uniformity correction method as described in claim 1, characterized in that, The residual non-uniformity Y16c of the current background image is obtained using the following formula: Y16c=k X16-Base-offset1-k offset2; Where k is the gain coefficient when performing two-point correction on the infrared image; Base is the current background image acquired by the infrared detector of the infrared imaging device during the process of the infrared imaging device changing from a cold state to a thermal equilibrium state; X16 is the original infrared image data output by the infrared detector of the infrared imaging device before performing two-point correction; offset1 and offset2 are the initial offset parameter and gain offset parameter, respectively.

7. The shutterless non-uniformity correction method as described in claim 1, characterized in that, The process of obtaining the background image bias parameters based on the change in residual non-uniformity includes the following steps: The residual non-uniformity change of the background image is obtained during the process of the infrared imaging device changing from a cold state to a thermal equilibrium state, and this is used as the process bias template M. rn ; The process bias parameter offset3 is obtained using the following formula: offset3=coef3 M rn ; Where coef3 is the process bias adaptive coefficient.

8. The shutterless non-uniformity correction method as described in claim 7, characterized in that, Obtaining the process bias adaptive coefficient coef3 includes the following steps: Obtaining the process bias template M rn The average pixel value and the center pixel value of the entire image; Process bias template M rn The pixel value of each pixel in the image is subtracted from the center pixel value of the entire image to obtain the offset-free template image; Divide the offset-free template image into blocks; The variance between the current background image and the offset template image blocks is obtained using the following formula: ； Among them, IMG Ni Y16c represents the current residual non-uniformity of the background image; D represents the variance. Furthermore, the coefficient coef3 corresponding to the minimum value of function f can be obtained using the following formula: 。 9. A shutterless non-uniformity correction system for implementing the shutterless non-uniformity correction method of claim 1, characterized in that, include: The initial bias parameter acquisition unit is used to acquire the initial bias parameters of the background image. The gain bias parameter acquisition unit is used to acquire the gain bias parameter of the background image based on the change in infrared image data output by the infrared detector when the infrared imaging device changes from a cold state to a thermal equilibrium state. The residual non-uniformity acquisition unit is used to determine the residual non-uniformity of the current background image acquired by the infrared detector of the infrared imaging device during the process of the infrared imaging device changing from a cold state to a thermal equilibrium state. The process bias parameter acquisition unit is used to acquire the process bias parameters of the background image based on the residual non-uniformity change of the background image during the process of the infrared imaging device from the cold state to the thermal equilibrium state. The image correction unit is used to perform non-uniformity correction on the current infrared image based on the initial bias parameter, gain bias parameter, and process bias parameter.

Images