A temperature drift correction method without baffle non-uniformity correction

Abstract

The present invention discloses a temperature drift correction method for non-blocking non-uniform correction, which obtains the difference between the blocked and unblocked results of the image by subtracting them, and then calculates the compensation value of the unblocked background, so as to achieve the purpose of correcting the non-blocking non-uniform correction background. The present invention solves the two problems of how to calculate the compensation and how to transmit the compensation, and absorbs the adaptive feedback idea, based on the loss function of the ideal value and the actual value of the corresponding pixel in the hidden layer of the neural network, completes the coefficient update through the gradient descent principle, and adjusts whether to update the compensation according to the sign of the background transformation.

Description

Technical Field

[0001] The present invention relates to the field of non-uniformity correction processing, and in particular to a temperature drift correction method for non-baffle non-uniformity correction (NUC). Background Art

[0002] When an uncooled infrared thermal imager is working, because the response of each detector element will vary with the change of radiation, a specific method is required to perform non-uniformity correction. At present, the most common correction method is the two-point correction method. Since the temperature of the detector is unstable, the image obtained by only two-point correction will produce stripe noise due to temperature drift, so the traditional non-uniformity correction method also requires a shield (or shutter) to cover the lens from time to time to correct the temperature drift.

[0003] Most of the existing non-baffle non-uniformity correction methods require calibration in high and low temperature chambers, which requires a cumbersome calibration process and expensive fixed costs, and also requires waterproofing work in advance, and the success rate is relatively low.

[0004] The Chinese patent application with publication number CN105841821A discloses a non-uniformity correction device and method based on calibration without baffles. The invention stores pot lid images of different detector shell temperatures in FLASH through a calibration module. When working, the parameter calling module calls the pot lid image and non-uniformity correction parameter K in FLASH into SDRAM, and the SDRAM reading module reads the non-uniformity correction parameter K. At the same time, the two frames of pot lid images containing T in SDRAM are read according to the real-time input detector shell temperature T. Although the invention has also improved the success rate of non-uniformity correction processing to a certain extent, it has the problems of complicated steps, many modules required, and inability to process all noises at one time. Summary of the invention

[0005] The technical problem solved by the present invention is: to overcome the cumbersome calibration process and expensive fixed cost of the traditional technology in the field of non-uniformity correction processing, and to provide a temperature drift correction method for non-uniformity correction without baffles, which also requires waterproofing in advance and has a low success rate. Through a baffle correction, the compensation value of the baffle-free background is calculated to correct the noise such as stripes and pot lids that appear in the detector due to temperature changes, so as to achieve the purpose of correcting the image. This method solves two problems: first, how to calculate the compensation; and second, how to transmit the compensation. The method absorbs the idea of ​​adaptive feedback, based on the loss function of the ideal value and the actual value of the corresponding pixel in the hidden layer of the neural network, and completes the coefficient update through the principle of gradient descent, and adjusts whether to update the compensation according to the sign of the background transformation. The cumbersome algorithm process of tracking drift is reduced.

[0006] The object of the present invention is achieved through the following technical solution: a temperature drift correction method without baffle non-uniform correction, characterized in that it includes the following steps:

[0007] Step 1. Obtain a frame of non-uniform correction image with block correction and save it;

[0008] Step 2. Get the current original image focal temperature vtemp;

[0009] Step 3. Find the two background Oh and Ol where the focal temperature vtemp is located;

[0010] Step 4. Obtain the slope k of the background where the current image is located;

[0011] Step 5. Obtain the offset Offset of the current image;

[0012] Step 6. Determine whether the machine has just been turned on or the segment has been changed; if so, the flag is set to 1, and the step length is -0.5, which is a fixed empirical value after debugging. If not, the flag is set to 0;

[0013] Step 7. Obtain the result of no file in the current frame;

[0014] Step 8. Subtract the current unobstructed result from the obstructed result to get the difference D between the two images. ij ;

[0015] Step 9. Determine the current flag bit (first frame or segment change flag). If it is 1, calculate the compensation values ​​G_cop and O_cop of G and O. If it is 0, do not update the compensation value and continue to use the original compensation value; avoid additional tracking algorithms to determine the image correction effect.

[0016] Step 10. Calculate the final compensation result;

[0017] Step 11. Update the difference D between the two images ij

[0018] Step 12: Determine whether the temperature drift correction is completed. If not, jump back to step 2.

[0019] Specifically, it is characterized in that the specific calculation formula of the offset Offset of the current image in step 5 is:

[0020] O = k*Oh+(K-1)*Ol;

[0021] Wherein, O is the offset after calibration.

[0022] Specifically, it is characterized in that the specific calculation formula of the current frame no-slot result in step 7 is:

[0023] Ynuc=Ysrc*G+O;

[0024] Among them, Ysrc is the original output of the detector, G is the correction gain after calibration, and Ynuc is the result after non-uniform correction.

[0025] Specifically, it is characterized in that the specific calculation formula for calculating the compensation values ​​G_cop and O_cop of G and O in step 9 is:

[0026] G_cop=—step*2*D ij *Ynuc

[0027] O_cop=—step*2*D ij .

[0028] Specifically, it is characterized in that the specific calculation formula of the final compensation result of step 10 is:

[0029] NUC=ysrc.*(G+G_cop)+(O+O_cop).

[0030] Specifically, it is characterized in that the step 11 updates the difference D between the two images ij The specific calculation formula is:

[0031] D ij =NUC-Ynuc.

[0032] Beneficial effects of the present invention:

[0033] The present invention calculates the compensation value of the unblocked background through a block correction, thereby achieving the purpose of correcting the unblocked NUC background. The recording of the background change state in the algorithm is also the tracking of the temperature drift of the detector. The state of the temperature drift is determined by the change of the flag, thereby judging whether the compensation value is updated. This logic overcomes the more calculation steps brought by parameter tracking. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying creative work.

[0035] Figure 1 It is a flow chart of the present invention. DETAILED DESCRIPTION

[0036] It should be understood that the specific embodiments described herein are only used to explain the present invention, and are not used to limit the present invention.

[0037] In order to have a clearer understanding of the technical features, purposes and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below. Obviously, the implementation cases described are part of the embodiments of the present invention, not all of the embodiments, and cannot be understood as limiting the scope of the implementation of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work belong to the protection scope of the present invention.

[0038] Embodiment 1:

[0039] In this embodiment, Figure 1 As shown, a temperature drift correction method without baffle non-uniform correction includes:

[0040] Step 1. Turn on the machine to obtain a frame of NUC image with block correction, which needs to be saved

[0041] Step 2. Get the current original image focal temperature vtemp

[0042] Step 3. Find the two background Oh and Ol where the focal temperature vtemp is located;

[0043] Step 4. Calculate the slope k of the background where the current image is located;

[0044] Step 5. Obtain the offset Offset of the current image according to the formula O=k*Oh+(K-1)*Ol;

[0045] Step 6. Determine whether the machine has just been turned on or the segment has been changed; if so, the flag is set to 1 and the step length is -0.5; if not, the flag is set to 0;

[0046] Step 7. Calculate the current frame no-file result according to the formula Ynuc=Ysrc*G+O

[0047] Step 8. Subtract the current unobstructed result from the obstructed result to obtain the difference Dij between the two images (note that the first calculation of the two frames of images is for the same scene).

[0048] Step 9. Determine the current flag bit (first frame or segment change flag). If it is 1, calculate the compensation values ​​G_cop and O_cop of G and O according to the formula. If it is 0, do not update the compensation value and continue to use the original compensation value.

[0049] G_cop=—step*2*D ij *Ynuc

[0050] O_cop=—step*2*D ij .

[0051] Step 10. Calculate the final compensation result according to the non-blocking formula NUC=ysrc.*(G+G_cop)+(O+O_cop).

[0052] Step 11. Update the difference D between the two images ij =NUC-Ynuc

[0053] Step 12: Determine whether the temperature drift correction is completed. If not, jump back to step 2.

[0054] The above shows and describes the basic principles, main features and advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited by the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of the present invention to be protected is defined by the attached claims and their equivalents.

[0055] It should be noted that, for the above-mentioned various method embodiments, for the sake of simplicity of description, they are all expressed as a series of action combinations, but those skilled in the art should be aware that this application is not limited by the order of the actions described, because according to this application, some steps can be performed in other orders or simultaneously. Secondly, those skilled in the art should also be aware that the embodiments described in the specification are all preferred embodiments, and the actions and units involved are not necessarily required by this application.

[0056] In the above embodiments, the description of each embodiment has its own emphasis. For parts that are not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0057] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiments can be implemented by instructing related hardware through a computer program, and the program can be stored in a computer-readable storage medium, and when the program is executed, it can include the processes of the embodiments of the above-mentioned methods. The storage medium can be a disk, an optical disk, a ROM, a RAM, etc.

[0058] The above disclosure is only the preferred embodiment of the present invention, which certainly cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are still within the scope of the present invention.

Claims

1. A temperature drift correction method without baffle non-uniform correction, characterized in that: The following steps are involved: Step 1. Obtain a frame of non-uniform correction image with block correction and save it; Step 2. Get the current original image focal temperature vtemp; Step 3. Find the two background Oh and Ol where the focal temperature vtemp is located; Step 4. Obtain the slope k of the background where the current image is located; Step 5. Obtain the offset Offset of the current image; The specific calculation formula of the offset Offset of the current image in step 5 is: O = k*Oh+(k-1)*Ol; Wherein, O is the offset after calibration; Step 6. Determine whether the machine has just been turned on or the segment has been changed; if so, the flag is set to 1 and the step length is -0.5; if not, the flag is set to 0; Step 7. Obtain the result of no block in the current frame; the specific calculation formula of the result of no block in the current frame in step 7 is: Ynuc=Ysrc*G+O; Among them, Ysrc is the original output of the detector, G is the correction gain after calibration, and Ynuc is the result after non-uniform correction; Step 8. Subtract the unobstructed result from the obstructed result of the current frame to obtain the difference D between the two images. ij ; Step 9. Determine the current flag bit representing the first frame or the segment change flag. If it is 1, calculate the compensation values ​​G_cop and O_cop of G and O. If it is 0, do not update the compensation value and continue to use the original compensation value. The specific calculation formula for calculating the compensation values ​​G_cop and O_cop of G and O in step 9 is: G_cop=—step*2*D ij *Ynuc; O_cop=—step*2*D ij ; Step 10. Calculate the final compensation result; the specific calculation formula of the final compensation result in step 10 is: NUC=Ysrc*(G+G_cop)+(O+O_cop); Step 11. Update the difference D between the two images ij ; Step 12: Determine whether the temperature drift correction is completed. If not, jump back to step 2.

2. A temperature drift correction method for non-uniform correction without baffles according to claim 1, characterized in that: The step 11 updates the difference D between the two images. ij The specific calculation formula is: D ij =NUC-Ynuc。

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