Shutter-free non-uniformity correction method and system

Abstract

The invention relates to a non-shutter non-uniformity correction method and system. The non-shutter non-uniformity correction method comprises the following steps: acquiring an initial offset parameter of a background image according to an infrared detector end background image and an infrared lens end background image; obtaining a gain offset parameter of the background image according to the infrared image data variation output by the infrared detector when the infrared imaging equipment is changed from a cold machine state to a heat balance state; determining the residual heterogeneity of a current background image acquired by an infrared detector of the infrared imaging equipment in the process of the infrared imaging equipment from a cold machine state to a heat balance state, and acquiring a process offset parameter of the background image according to the variable quantity of the residual heterogeneity; and performing non-uniformity correction on the current infrared image. According to the method, correction of the non-uniform background image can be decomposed into the initial bias parameter, the gain bias parameter and the process bias parameter, so that the ideal background image subjected to non-uniform correction is calculated, and non-uniform correction of the infrared image is realized under the condition of no shutter correction.

Description

Technical Field

[0001] The invention relates to the field of infrared imaging technology, and in particular to a shutter-free non-uniform correction method and system. Background Art

[0002] Since there are different non-uniformities in the response characteristics of each detection unit of the uncooled infrared detector, this non-uniformity will reduce the imaging quality of the infrared imaging system. In this regard, the more common non-uniformity correction method is to install a built-in shutter in the system and perform occlusion correction regularly. However, the addition of the shutter will increase the complexity of the detector's mechanical structure, limit the miniaturization of the detector, and increase the cost. At the same time, the shutter correction process will interrupt the image input, affecting the system's external observation and real-time tracking of the target.

[0003] Therefore, shutterless infrared image non-uniformity correction methods have been developed in the prior art, including: 1. A calibration-based non-uniformity correction method, which establishes a relationship model between the working state and the response of the detector to obtain different offline background images, and then selects the background image matching 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 over time, the response coefficient in the relationship model will produce a certain drift, resulting in poor correction effect; 2. A scene-based non-uniform correction method, which separates non-uniform noise and useful image information through statistical scene characteristics, obtains a real-time corrected background image through learning, and then performs non-uniform correction on the infrared image through the real-time corrected background image. This technical solution has a large amount of calculation and slow convergence speed when implemented, and there are many restrictions when used, such as the need to use hardware support such as gyroscopes or accelerometers, and relies on motion scenes, and has poor image correction effect in static scenes. Summary of the invention

[0004] The purpose of the present invention is to provide a shutter-free non-uniformity correction method and system, which can decompose the correction of the non-uniform background image acquired by the infrared detector into a starting bias parameter, a gain bias parameter and a process bias parameter, 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 the infrared image under the condition of no shutter correction.

[0005] To achieve the above object, the present invention provides the following technical solutions:

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

[0007] Obtaining initial bias parameters of the background image according to the background image at the infrared detector end and the background image at the infrared lens end;

[0008] The gain bias parameter of the background image is obtained according to the change amount of the infrared image data output by the infrared detector when the infrared imaging device changes from a cold state to a thermal equilibrium state;

[0009] 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, and obtain a process bias parameter of the background image according to the change amount of the residual non-uniformity;

[0010] The non-uniformity correction is performed on the current infrared image according to the starting offset parameter, the gain offset parameter, and the process offset parameter. Preferably, the starting offset parameter offset1 of the background image is obtained according to the following formula:

[0011] offset1 = coef 1i *(Y16 1i -Y16 2i )

[0012] Among them, coef 1i is the gain coefficient; Y16 1i 、Y16 2i They are respectively the corrected background image at the infrared detector end and the corrected background image at the infrared lens end.

[0013] Preferably, the corrected infrared detector end background image Y16 1i Through the infrared detector end background image Base1 i The low-frequency characteristics of are obtained based on two-point correction;

[0014] Corrected infrared lens end background image Y16 2i Through the infrared lens end background image Base2 i The low-frequency characteristics of the image are obtained based on two-point correction.

[0015] Preferably, the corrected infrared detector end background image Y16 is obtained by the following formula: 1i , infrared lens end background image Y16 2i :

[0016] Y16 1i =k*X16 1i -Base1i_ m

[0017] Y16 2i =k*X16 2i -Base2i_ m

[0018] Where k is the gain coefficient when performing two-point correction on the infrared image; X16 1iBase1 is the background image at the infrared detector end before two-point calibration i Original infrared image data; X16 2i Base2 is the background image at the infrared lens end before two-point calibration. i Original infrared image data; Base1 i_m 、Base2 i_m They are the background images Base1 at the infrared detector end i Low-frequency features of infrared lens end background image Base2 i low frequency characteristics.

[0019] Preferably, the gain bias parameter offset2 of the background image is obtained according to the following formula:

[0020] offset2=coef T1 *Δb=coef T1 *(X16 T1 -X16 T2 )

[0021] Among them, coef T1 is the multiplicative coefficient related to the focal plane temperature of the infrared detector of the infrared imaging device; Δb is the change in the 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 It is the infrared image data output by the infrared detector when the infrared imaging device is in the cold state. T2 It is the infrared image data output by the infrared detector when the infrared imaging device is in thermal equilibrium; T1 is the focal temperature change corresponding to Δb.

[0022] Preferably, the residual non-uniformity Y16c of the current background image is obtained according to the following formula:

[0023] Y16c=k*X16-Base-offset1-k*offset2

[0024] Among them, k is the gain coefficient when performing two-point correction on the infrared image; Base is the current background image obtained by the infrared detector of the infrared imaging device when the infrared imaging device changes 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 the two-point correction is performed; offset1 and offset2 are the starting offset parameter and gain offset parameter, respectively.

[0025] Preferably, obtaining the process bias parameter of the background image according to the variation of the residual non-uniformity comprises the following steps:

[0026] Obtain 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, and use it as the process bias template M rn ;

[0027] Obtain the process offset parameter offset3 according to the following formula:

[0028] offset3=coef3*M rn

[0029] Among them, coef3 is the process bias adaptation coefficient.

[0030] 8. The shutterless non-uniformity correction method according to claim 7, wherein obtaining the process bias adaptive coefficient coef3 comprises the following steps:

[0031] Get process bias template M rn The pixel mean value of the whole image and the pixel center value of the whole image;

[0032] Set the process offset template M rn Subtract the pixel value of each pixel in the image from the pixel center value of the whole image to obtain the template image after de-shifting;

[0033] Divide the template image after de-shifting into blocks;

[0034] The variance between the current background image and the block of the template image after de-shifting is obtained according to the following formula:

[0035]

[0036] Among them, IMG Ni is the current residual non-uniformity Y16c of the background image; D represents the variance;

[0037] And according to the following formula, the corresponding coefficient coef3 is obtained when the function f value is minimum:

[0038]

[0039] Preferably, the non-uniformity correction is performed according to the following formula:

[0040] NUC=Y16c-offset3=k*X160-Base0-offset1-k*offset2-offset3

[0041] Among them, 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 original infrared image data output by the infrared detector of the infrared imaging device before the two-point correction; offset1, offset2, and offset3 are the starting offset parameter, gain offset parameter, and process offset parameter, respectively.

[0042] On the other hand, a shutter-free non-uniformity correction system is also provided, comprising:

[0043] An initial bias parameter acquisition unit, which is used to acquire the initial bias parameter of the background image;

[0044] A gain bias parameter acquisition unit, which is used to acquire the gain bias parameter of the background image according to the change amount of the infrared image data output by the infrared detector when the infrared imaging device changes from a cold state to a thermal equilibrium state;

[0045] A residual non-uniformity acquisition unit, which 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;

[0046] A process bias parameter acquisition unit, which is used to acquire the process bias parameter of the background image according to the residual non-uniformity change amount of the background image during the process of the infrared imaging device changing from a cold machine state to a thermal equilibrium state;

[0047] The image correction unit is used to perform non-uniformity correction on the current infrared image according to the initial bias parameter, the gain bias parameter and the process bias parameter.

[0048] In summary, the present invention has the following beneficial effects compared with the prior art:

[0049] The present invention has the following advantages:

[0050] The present invention decomposes the correction of the non-uniform background image acquired by the infrared detector into a starting bias parameter, a gain bias parameter and a process bias parameter, so as to automatically calculate the ideal background image for non-uniform correction in real time, and further realizes the non-uniform correction of the infrared image without shutter correction. It solves the problems of poor correction effect caused by drift of the response coefficient and excessive dependence on the scene and hardware in the scene-based non-uniform correction method. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a flowchart of the steps of the shutter-free non-uniform correction method of the present invention;

[0052] Figure 2 are infrared images before and after being processed by the correction method of the present invention;

[0053] Figure 3 It is a structural schematic diagram of the shutter-free non-uniformity correction system of the present invention. DETAILED DESCRIPTION

[0054] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0055] Example 1

[0056] like Figure 1 As shown, this embodiment provides a shutter-free non-uniformity correction method, which is applicable to an uncooled infrared imaging device. Specifically, the shutter-free non-uniformity correction method includes the following steps:

[0057] S1, directly acquiring a background image through an infrared detector of an infrared imaging device, and acquiring a background image through an optical component consisting of an infrared lens and an infrared detector of the same infrared imaging device, and acquiring a starting offset parameter offset1 of the background image, wherein the starting offset parameter offset1 is a differential offset between thermal radiation outside the lens of the infrared imaging device and thermal radiation inside the lens; in this embodiment, the infrared imaging device includes an uncooled infrared thermal imager, and directly acquiring a background image through the infrared detector of the infrared imaging device means that the infrared detector directly senses light from an external object (such as a black body), thereby acquiring an infrared image, and determining the background image based on the infrared image, and acquiring a background image through an optical component consisting of an infrared lens and an infrared detector of the same infrared imaging device means that light from an external object first passes through the infrared lens and then is sensed by the infrared detector, thereby acquiring an infrared image, and determining the background image based on the infrared image;

[0058] Specifically, step S1 includes the following steps:

[0059] At the same ambient temperature, the infrared image of the black body with the same temperature (such as black body t1, t2 and t3, etc.) is directly obtained through the infrared detector of the infrared imaging device, and the background image Base1 at the infrared detector end is determined according to the infrared image. i ;

[0060] At the same ambient temperature, the infrared image of the black body with the same temperature (such as black body t1, t2 and t3, etc.) is obtained through the optical assembly composed of the infrared lens and the infrared detector of the same infrared imaging device, and the background image Base2 at the infrared lens end is determined according to the infrared image. i; Background image Base1 at the infrared detector end i , infrared lens end background image Base2 i All are infrared images;

[0061] For the background image Base1 of the infrared detector i , infrared lens end background image Base2 i All the mean or center values ​​are returned to zero.

[0062] The background image Base1 of the infrared detector end after the mean or center value is zeroed i , infrared lens end background image Base2 i Low-frequency features are extracted and the background image Base1 from the infrared detector is i The low-frequency features extracted from the image are used as the first background image correction parameter Base1 i_m , and the background image Base2 from the infrared lens i The low-frequency features extracted from the image are used as the second background image correction parameter Base2 i_m ; Further, the extraction of the low-frequency features can be achieved by using a mean filter, a median filter, a Gaussian filter, etc. For example, in this embodiment, a 5*5 Gaussian filter (sigma=5) is used to extract the low-frequency features;

[0063] Correct the parameter Base1 by the first background image i_m For the background image Base1 of the infrared detector i Perform two-point calibration to obtain the corrected background image Y16 at the infrared detector end 1i ; and, by the second background image correction parameter Base2 i_m Base2 for the background image at the infrared lens end i Perform two-point calibration to obtain the corrected infrared lens end background image Y16 2i For example, in this embodiment, the corrected background image Y16 at the infrared detector end can be obtained by formulas (1)-(2) 1i , infrared lens end background image Y16 2i :

[0064] Y16 1i =k*X16 1i -Base1 i_m (1)

[0065] Y16 2i =k*X16 2i -Base2 i_m (2)

[0066] Where k is the gain coefficient for two-point correction of infrared images, and its value range is [0.8-1.2]; X16 1i Base1 is the background image at the infrared detector end before two-point calibration i Original infrared image data; X16 2i Base2 is the background image at the infrared lens end before two-point calibration. i The original infrared image data;

[0067] According to formula (3), the starting offset parameter offset1 of the background image is obtained:

[0068] offset1 = coef 1i *(Y16 1i -Y16 2i ) (3)

[0069] Among them, coef 1i is the gain coefficient, which can be calculated based on the background image Base1 at the infrared detector end i , infrared lens end background image Base2 i Relative to the black body temperature T i The change in the value is obtained by least square fitting. The specific process includes: determining the best function matching of the data by calculating the minimum square sum of the error, so that the square sum of the error between the obtained data and the actual data is minimized. The smaller the mean square error, the better the fitting effect; fitting the first background image correction parameter Base1 i_m and the second background image correction parameter Base2 i_m The difference between the black body temperature T i The relationship between the black body temperature T i The gain coefficient coef under 1i ;

[0070] S2, obtaining a gain offset parameter offset2 of a background image according to a 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, wherein the gain offset parameter offset2 of the background image refers to the process non-uniformity of the infrared detector response caused by the increase in the internal temperature of the infrared imaging device as the copying time increases after the infrared imaging device is turned on;

[0071] Specifically, step S2 obtains the gain offset parameter offset2 of the background image in real time according to formula (4):

[0072] offset2=colef T1 *Δb=coef t1 *(X16 T1 -X16T2 ) (4)

[0073] Among them, coef T1 is a multiplicative coefficient related to the focal plane temperature of the infrared detector of the infrared imaging device, which may be a first-order, second-order or multi-order function of the focal plane temperature. For example, in this embodiment, coef T1 =a1+a2*T1+a3*T1 2 +...+a n-1 *T1 n , a1, a2, a3...a n-1 are the focal temperature coefficients, n is the highest power of the multi-time function, which is determined according to the defined power fitting method; 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 It is the infrared image data output by the infrared detector when the infrared imaging device is in the cold state. T2 It is the infrared image data output by the infrared detector when the infrared imaging device is in thermal equilibrium. T1 、X16 T2 All are infrared image data before two-point correction; T1 is the focal temperature change corresponding to Δb;

[0074] S3, determining 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, wherein the residual non-uniformity Y16c refers to the residual infrared image non-uniformity after the current background image is subjected to non-uniformity correction processing such as the two-point correction in step S1;

[0075] Specifically, step S3 obtains the residual non-uniformity Y16c of the current background image in real time according to formula (5):

[0076] Y16c=k*X16-Base-offset1-k*offset2 (5)

[0077] Wherein, k is the gain coefficient when performing two-point correction on the infrared image, and its value range is [0.8-1.2]; Base is the current background image acquired by the infrared detector of the infrared imaging device when the infrared imaging device changes from the cold state to the thermal equilibrium state; X16 is the original infrared image data output by the infrared detector of the infrared imaging device before the two-point correction is performed;

[0078] S4, obtaining a process bias parameter offset3 of the background image according to a residual non-uniformity variation of the background image during a process in which the infrared imaging device changes from a cold state to a thermal equilibrium state;

[0079] Specifically, step S4 includes the following steps:

[0080] Obtain 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, and use it as the process bias template M rn ;

[0081] According to formula (5), the process offset parameter offset3 is obtained:

[0082] offset3=coef3*M rn (6)

[0083] Among them, coef3 is the process bias adaptive coefficient, and its value range is [-2,2];

[0084] Further, obtaining the process bias adaptive coefficient coef3 includes the following steps:

[0085] Get process bias template M rn The pixel mean value of the whole image and the pixel center value of the whole image;

[0086] Set the process offset template M rn Subtract the pixel value of each pixel in the image from the pixel center value of the whole image to obtain the template image after de-shifting;

[0087] The template image after de-shifting is divided into two blocks. For example, in this embodiment, the template image after de-shifting is divided into two blocks. n blocks, where n is an even number greater than or equal to 4, such as n=6;

[0088] According to formula (7), the variance between the blocks of the current background image and the template image after de-shifting is obtained:

[0089]

[0090] Among them, IMG Ni is the current residual non-uniformity Y16c of the background image; D represents the variance;

[0091] And according to formula (8), the corresponding coefficient coef3 is obtained when the function f value is minimum, and the coefficient coef3 is used to calculate the process offset parameter offset3:

[0092]

[0093] Where E represents mathematical expectation;

[0094] And S5, performing non-uniformity correction on the current infrared image according to the starting offset parameter offset1, the gain offset parameter offset2, and the process offset parameter offset3, and finally obtaining an infrared image after non-uniformity correction under a shutter-free condition;

[0095] Specifically, in step S4, non-uniformity correction is performed according to formula (9):

[0096] NUC=Y16c-offset3=k*X160-Base0-offset1-k*offset2-offset3 (9)

[0097] Among them, NUC is the infrared image after non-uniformity correction; k is the gain coefficient when performing two-point correction on the infrared image, and its value range is [0.8-1.2]; Base0 is the current background image, which can be the default background image after the infrared imaging device is turned on. The background image can be obtained by collecting a black body or a built-in reference uniform surface image after the infrared imaging device is turned on; X160 is the original infrared image data output by the infrared detector of the infrared imaging device before the two-point correction is performed.

[0098] 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: a starting bias parameter, a gain bias parameter and a process bias parameter, so as to automatically calculate the ideal background image for non-uniformity correction in real time, and further realize the non-uniformity correction of the infrared image without shutter correction. It solves the problem of poor correction effect caused by drift of the response coefficient and excessive dependence on the scene and hardware in the scene-based non-uniformity correction method. The algorithm complexity of the whole process is low and the amount of calculation is small.

[0099] Figure 1 Part (a) shows the uncorrected infrared image half an hour after the infrared imaging device was turned on. Figure 1 Part (b) in FIG. 1 is an infrared image processed by the non-uniformity correction method in this embodiment. It can be seen from the infrared image that the non-uniformity is effectively corrected and the image quality is significantly improved.

[0100] Embodiment 2:

[0101] This embodiment provides a shutter-free non-uniformity correction system, which can implement the shutter-free non-uniformity correction method described in Embodiment 1. Figure 3 As shown, the shutter-free non-uniformity correction system includes:

[0102] The infrared detector end background image acquisition unit 1 is used to determine the infrared detector end background image Base1 according to the infrared image of the same temperature black body (such as black body t1, t2 and t3, etc.) directly acquired by the infrared detector of the infrared imaging device at the same ambient temperature i ;

[0103] The infrared lens end background image acquisition unit 2 is used to determine the infrared lens end background image Base2 according to the infrared image of the same temperature black body (such as black body t1, t2 and t3, etc.) acquired by the optical assembly of the same infrared imaging device, which is composed of an infrared lens and an infrared detector, at the same ambient temperature. i ;

[0104] The feature extraction unit 3 is used to extract the background image Base1 of the infrared detector end after the mean value or the center value is zeroed. i , infrared lens end background image Base2 i Low-frequency feature extraction is performed on both, where the background image Base1 from the infrared detector end i The low-frequency features extracted from the image are used as the first background image correction parameter Base1 i_m , from the infrared lens end background image Base2 i The low-frequency features extracted from the image are used as the second background image correction parameter Base2 i_m ;

[0105] A two-point correction unit 4 is used to correct the parameter Base1 by using the first background image. i_m For the background image Base1 of the infrared detector i Perform two-point calibration to obtain the corrected background image Y16 at the infrared detector end 1i ; and, by the second background image correction parameter Base2 i_m Base2 for the background image at the infrared lens end i Perform two-point calibration to obtain the corrected infrared lens end background image Y16 2i ; The specific process is the same as step S1;

[0106] An initial offset parameter acquisition unit 5 is used to acquire an initial offset parameter offset1 of the background image according to formula (3);

[0107] The gain offset parameter acquisition unit 6 is used to acquire the gain offset parameter offset2 of the background image according to the change amount of the infrared image data output by the infrared detector when the infrared imaging device changes from a cold state to a thermal equilibrium state; the specific process is the same as step S2;

[0108] 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; the specific process is the same as step S3;

[0109] A process offset parameter acquisition unit 8 is used to acquire a process offset parameter offset3 of the background image according to a residual non-uniformity variation of the background image during a process of the infrared imaging device changing from a cold state to a thermal equilibrium state; the specific process is the same as step S4;

[0110] The image correction unit 9 is used to perform non-uniformity correction on the current infrared image according to the starting offset parameter offset1, the gain offset parameter offset2, and the process offset parameter offset3, and finally obtain an infrared image after non-uniformity correction under the condition of no shutter; its specific process is the same as step S5.

[0111] In summary, the present application decomposes the correction of the non-uniform background image acquired by the infrared detector into a starting bias parameter, a gain bias parameter and a process bias parameter, so as to calculate the ideal background image for non-uniform correction in real time and automatically, and further realizes the non-uniform correction of the infrared image without shutter correction. It solves the problem of poor correction effect caused by drift of the response coefficient and excessive dependence on the scene and hardware in the scene-based non-uniform correction method.

[0112] 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 principle of the present invention should be included in the protection scope of the present invention.

Claims

1. A shutter-free non-uniform correction method, characterized in that: The steps include: Obtaining initial bias parameters of the background image according to the background image at the infrared detector end and the background image at the infrared lens end; The gain bias parameter of the background image is obtained according to the change amount of the infrared image data output by the infrared detector when the infrared imaging device changes from a cold state to a thermal equilibrium state; 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, and obtain a process bias parameter of the background image according to the change amount of the residual non-uniformity; The non-uniformity correction is performed on the current infrared image according to the initial bias parameter, the gain bias parameter and the process bias parameter.

2. The shutter-free non-uniform correction method according to claim 1, characterized in that: Obtain the starting offset parameter offset1 of the background image according to the following formula: offset1=coef 1i *(Y16 1i -Y16 2i ) Among them, coef 1i is the gain coefficient; Y16 1i 、Y16 2i They are respectively the corrected background image at the infrared detector end and the corrected background image at the infrared lens end.

3. The shutter-free non-uniform correction method according to claim 2, characterized in that: Corrected infrared detector end background image Y16 1i Through the infrared detector end background image Base1 i The low-frequency characteristics of are obtained based on two-point correction; Corrected infrared lens end background image Y16 2i Through the infrared lens end background image Base2 i The low-frequency characteristics of the image are obtained based on two-point correction.

4. The shutter-free non-uniform correction method according to claim 3, characterized in that: The corrected background image Y16 of the infrared detector end is obtained by the following formula 1i , infrared lens end 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 when performing two-point correction on the infrared image; X16 1i Base1 is the background image at the infrared detector end before two-point calibration i Original infrared image data; X16 2i Base2 is the background image at the infrared lens end before two-point calibration. i Original infrared image data; Base1 i_m 、Base2 i_m They are the background images Base1 at the infrared detector end i Low-frequency features of infrared lens end background image Base2 i low frequency characteristics.

5. The shutter-free non-uniform correction method according to claim 1, characterized in that: Obtain the gain bias parameter offset2 of the background image according to the following formula: offset2=coef T1 *Δb=coef T1 *(X16 T1 -X16 T2 ) Among them, coef T1 is the multiplicative coefficient related to the focal plane temperature of the infrared detector of the infrared imaging device; Δb is the change in the 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 It is the infrared image data output by the infrared detector when the infrared imaging device is in the cold state. T2 It is the infrared image data output by the infrared detector when the infrared imaging device is in thermal equilibrium; T1 is the focal temperature change corresponding to Δb.

6. The shutter-free non-uniform correction method according to claim 1, characterized in that: The residual non-uniformity Y16c of the current background image is obtained according to the following formula: Y16c=k*X16-Base-offset1-k*offset2 Among them, k is the gain coefficient when performing two-point correction on the infrared image; Base is the current background image obtained by the infrared detector of the infrared imaging device when the infrared imaging device changes 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 the two-point correction is performed; offset1 and offset2 are the starting offset parameter and gain offset parameter, respectively.

7. The shutter-free non-uniform correction method according to claim 1, characterized in that: The process bias parameter of the background image is obtained according to the variation of the residual non-uniformity, including the following steps: Obtain 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, and use it as the process bias template M rn ; Obtain the process offset parameter offset3 according to the following formula: offset3=coef3*M rn Among them, coef3 is the process bias adaptation coefficient.

8. The shutterless non-uniformity correction method according to claim 7, characterized in that: Obtaining the process bias adaptive coefficient coef3 includes the following steps: Get process bias template M rn The pixel mean value of the whole image and the pixel center value of the whole image; Set the process offset template M rn Subtract the pixel value of each pixel in the image from the pixel center value of the whole image to obtain the template image after de-shifting; Divide the template image after de-shifting into blocks; The variance between the current background image and the block of the template image after de-shifting is obtained according to the following formula: Among them, IMG Ni is the current residual non-uniformity Y16c of the background image; D represents the variance; And according to the following formula, the corresponding coefficient coef3 is obtained when the function f value is minimum:

9. The shutter-free non-uniform correction method according to claim 1, characterized in that: The non-uniformity correction is performed according to the following formula: NUC=Y16c-offset3=k*X160-Base0-offset1-k*offset2-offset3 Among them, 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 original infrared image data output by the infrared detector of the infrared imaging device before the two-point correction; offset1, offset2, and offset3 are the starting offset parameter, gain offset parameter, and process offset parameter, respectively.

10. A shutter-less non-uniformity correction system, characterized in that: include: An initial bias parameter acquisition unit, which is used to acquire the initial bias parameter of the background image; A gain bias parameter acquisition unit, which is used to acquire the gain bias parameter of the background image according to the change amount of the infrared image data output by the infrared detector when the infrared imaging device changes from a cold state to a thermal equilibrium state; A residual non-uniformity acquisition unit, which 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; A process bias parameter acquisition unit, which is used to acquire the process bias parameter of the background image according to the residual non-uniformity change amount of the background image during the process of the infrared imaging device changing from a cold machine state to a thermal equilibrium state; The image correction unit is used to perform non-uniformity correction on the current infrared image according to the initial bias parameter, the gain bias parameter and the process bias parameter.

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