A method and apparatus for focusing a tracking target

Abstract

This invention discloses a target tracking focusing method and apparatus, comprising: acquiring infrared image data of the target being tracked using an infrared optical system; determining a sharpness parameter of a sub-image region related to the target in the infrared image data; determining focusing parameters of the infrared optical system based on the sharpness parameter of the sub-image region; focusing the infrared optical system using the focusing parameters; and ending the focusing process when the desired sharpness is achieved. This embodiment utilizes the sharpness parameter of a sub-image region related to the target in the infrared image data of the tracked target for focusing. This allows for improvements in target detection and tracking distance, distance limits, and target tracking stability without altering the target tracking algorithm.

Description

Technical Field

[0001] This invention relates to the field of optoelectronic systems technology, and in particular to a method and apparatus for focusing a tracking target. Background Technology

[0002] During the remote target tracking or detection process of airborne optoelectronic radar or airborne search and tracking systems, as the target distance changes, especially when the tracked remote target is in a tail-fly transition state, the distance between the target and the optical receiving window increases, and the signal-to-noise ratio decreases. Existing target tracking and prediction algorithms usually improve the minimum signal-to-noise ratio threshold of the algorithm, but no matter how high the performance of the signal processing algorithm is, it will lose the tracked target after a certain signal processing threshold.

[0003] Manual focusing is difficult to determine in a very short time, and while autofocus technology is mature, global focusing is difficult to play a role in complex backgrounds. Summary of the Invention

[0004] This invention provides a target focusing method and apparatus to improve the maximum detection and tracking distance of an optoelectronic system.

[0005] This invention proposes a target tracking and focusing method, comprising:

[0006] While tracking a target using an infrared optical system, infrared image data of the target is acquired based on the infrared optical system.

[0007] Determine the sharpness parameters of the sub-image regions related to the target in the infrared image data;

[0008] The focusing parameters of the infrared optical system are determined based on the sharpness parameters of the sub-image region.

[0009] The infrared optical system is focused using the aforementioned focusing parameters, and the focusing process ends when the desired clarity is achieved.

[0010] In some embodiments, the infrared image data is acquired by receiving radiation from the infrared optical system using an infrared detector;

[0011] Determining the sharpness parameters of the sub-image region related to the target in the infrared image data includes:

[0012] The target neighborhood range of a preset size in the infrared image data is taken as the sub-image region;

[0013] Calculate the sharpness parameter of the sub-image region.

[0014] In some embodiments, the sharpness parameter of the sub-image region is calculated using one of the following methods: gradient contrast method, sharpness variance, multi-frame grayscale change comparison, and wavelet transform of infrared image.

[0015] In some embodiments, before focusing the infrared optical system according to the focusing parameters, the target tracking focusing method further includes:

[0016] The change in distance between the target and the infrared optical system is determined based on Kalman filtering.

[0017] Focusing the infrared optical system according to the focusing parameters includes:

[0018] The infrared optical system is focused based on the change in distance and the sharpness of the sub-image region.

[0019] In some embodiments, the target tracking focusing method further includes:

[0020] When tracking multiple targets using an infrared optical system, determine the sharpness of each sub-image region related to the multiple targets;

[0021] Weight the sharpness of each sub-image region;

[0022] The focusing parameters of the infrared optical system are determined based on the weighted results.

[0023] In some embodiments, the target tracking focusing method further includes:

[0024] Scan and record the location information of each target;

[0025] When the target appears, focusing is performed based on the target's location information and the determined focusing parameters.

[0026] In some embodiments, the target tracking focusing method further includes:

[0027] Configure the initial tracking parameters of the infrared optical system according to the tracking environment;

[0028] The target is tracked based on the initial tracking parameters.

[0029] In some embodiments, the target tracking focusing method further includes:

[0030] A user interface is provided, and the focusing parameters are presented to the user based on the infrared image data through the user interface.

[0031] The present invention also proposes a target tracking focusing device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the computer program is executed by the processor, it implements the steps of the target tracking focusing method described in the embodiments of the present disclosure.

[0032] The present invention also proposes a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the target tracking and focusing method described in the embodiments of the present disclosure.

[0033] This invention relates to a method for focusing by determining the sharpness parameters of target-related sub-image regions within the infrared image data of the tracked target. This allows for improvements in target detection and tracking distance, range limits, and tracking stability without altering the target tracking algorithm.

[0034] The above description is merely an overview of the technical solution of the present invention. In order to better understand the technical means of the present invention and to implement it in accordance with the contents of the specification, and in order to make the above and other objects, features and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described below. Attached Figure Description

[0035] Various other advantages and benefits will become apparent to those skilled in the art upon reading the following detailed description of preferred embodiments. The accompanying drawings are for illustrative purposes only and are not intended to limit the invention. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0036] Figure 1 This is a basic flowchart of the target focusing method according to an embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram of the basic structure of the optoelectronic system according to an embodiment of the present invention;

[0038] Figure 3 This is a schematic diagram of the overall process of the target tracking and focusing method according to an embodiment of the present invention. Detailed Implementation

[0039] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0040] In the process of long-range target tracking or detection by airborne electro-optical radar or airborne search and tracking systems, the signal-to-noise ratio of the target decreases as the distance between the target and the electro-optical detection equipment increases. Therefore, an effective automatic focusing technology is needed to replace manual or global focusing. Generally, aerial targets are detected as point targets at the maximum range, hence the following formula:

[0041]

[0042] Where δ is the signal process factor, τ a τ0 and D0 represent atmospheric transmittance and optical system transmittance, respectively. 2 For the optical effective aperture, D * The detection rate of the detection system, SNRTH The signal-to-noise ratio (SNR) threshold for the detection algorithm is determined by its performance. a and b are the pixel sizes of the detector, and Δf is the detector's signal bandwidth. Clearly, once the detection system and the surrounding atmospheric environment are determined, these parameters cannot be changed. I is the difference in radiation intensity between the target and the background. To increase the maximum detection distance, the difference in radiation intensity between the target and the background can only be increased by adjusting the focus or the integration time. Furthermore, increasing the target's radiation intensity can be achieved by changing the focal length, preventing the target from becoming out of focus due to distance changes. Target imaging, from the lens imaging formula, has:

[0043]

[0044] In equation (2), D 物 For the object distance of the optical system, d 像 For the image distance of the optical system, f 焦距 For a fixed-focus optical system, the focal length cannot be changed. When the distance between the remote target and the optical window changes, the system can only focus by changing the image distance. However, it is difficult to simply change the image distance after the detector lens assembly is completed. Usually, several lenses in the lens assembly are moved back and forth along the axis, which is equivalent to changing the image distance. This satisfies the above formula and allows the target energy to be focused onto the focal plane.

[0045] Based on this, the present invention proposes a method for ensuring automatic focusing of targets at different distances, with different target sizes and types, and with different background complexities, such as... Figure 1 As shown, it includes:

[0046] In step S101, while the target is being tracked using an infrared optical system, infrared image data for target tracking is acquired based on the infrared optical system. Specifically, a preset target tracking and detection algorithm can be used to track the target and send real-time miss distances to the servo control system, thus fixing the target within a preset area. In this disclosure, the preset target tracking and detection algorithm may include linear regression, Kalman filtering, deep learning-based prediction, etc., and specific target tracking algorithms are not limited here. For example, a tracking box can be set as the preset area, and the target can be positioned in the middle of the tracking box for target tracking. Figure 2 As shown, the real-time focusing system of the present invention includes an infrared optical system and an infrared detector. The infrared image data in this application can be obtained by receiving radiation from the infrared optical system through the infrared detector, and is 16-bit raw energy distribution data, rather than energy-stretched data such as histograms.

[0047] In step S102, the sharpness parameter of the sub-image region related to the target in the infrared image data is determined. For the current frame of infrared image data, this step further determines the sharpness parameter of the target-related sub-image region in the frame of infrared image data. For example, an extended bounding box can be delineated based on the aforementioned tracking box as the sub-image region, or a bounding box can be selected based on the neighborhood of the target's location as the sub-image region. This can be implemented using appropriate algorithms, and the specific methods are not limited here. Then, the sharpness parameter of the sub-image region is determined. The sharpness parameter referred to in this application is a parameter related to the sharpness of the target in the image. The sharper the target is in the infrared image, the higher this parameter can be. Processing only the sharpness of local infrared images can improve the efficiency of image processing.

[0048] In step S103, the focusing parameters of the infrared optical system are determined based on the sharpness parameters of the sub-image region.

[0049] In step S104, the infrared optical system is focused using the focusing parameters, and focusing ends when the desired sharpness is achieved. Specifically, the infrared optical system can be adjusted based on the focusing parameters determined by the sharpness parameters to improve the sharpness of the target in the acquired infrared image, and fine-tuning in either the forward or reverse direction can be performed. In this application, the sharpness parameters and focusing parameters can satisfy a preset mapping rule, so that when the sharpness parameters are determined, the focusing parameters can also be determined simultaneously.

[0050] This invention relates to a method for focusing by determining the sharpness parameters of target-related sub-image regions within the infrared image data of the tracked target. This allows for improvements in target detection and tracking distance, range limits, and tracking stability without altering the target tracking algorithm.

[0051] In some embodiments, determining the sharpness parameter of the sub-image region related to the target in the infrared image data includes:

[0052] The target neighborhood range of a preset size in the infrared image data is taken as the sub-image region;

[0053] Calculate the sharpness parameter of the sub-image region.

[0054] Specifically, for example, a 20*20 pixel neighborhood of the target can be used as a sub-image region. The selected neighborhood range can also be determined by adaptively changing the neighborhood range based on the target size. For instance, an airborne electro-optical radar can be used to measure the distance to the key target using laser ranging, calculate the target imaging scale using infrared images, and then determine the selected neighborhood range by adaptively changing the neighborhood range based on the target size. By selecting an appropriate neighborhood range, the computational load required by the method in this application can be greatly reduced, thereby improving the system's response speed.

[0055] In some embodiments, the sharpness parameter of the sub-image region is calculated using one of the following methods: gradient contrast method, sharpness variance, multi-frame grayscale change comparison, and wavelet transform of infrared image.

[0056] Specifically, the gradient contrast method requires the least amount of computation and can achieve an ideal system response speed. In situations where computational speed is not critical, contrast evaluation metrics such as sharpness variance, multi-frame grayscale variation contrast, and wavelet transform of infrared images can be used.

[0057] In some embodiments, before focusing the infrared optical system according to the focusing parameters, the target tracking focusing method further includes: determining the change in distance between the target and the infrared optical system based on Kalman filtering.

[0058] Focusing the infrared optical system according to the focusing parameters includes:

[0059] The infrared optical system is focused based on the change in distance and the sharpness of the sub-image region.

[0060] Specifically, during target tracking, the focusing system operates dynamically, and the target distance changes continuously. Therefore, the focusing process cannot be divided into two stages: coarse adjustment and fine adjustment. Furthermore, in the specific application of the method disclosed herein, the motor control unit is integrated with the laser ranging module. The method of this disclosure uses Kalman filtering to predict the distance change of the target relative to the photoelectric device, thereby allowing for advance estimation of the focusing direction (positive or negative). This, combined with the local sharpness of the target, guides the motor control unit to send the corresponding focusing change.

[0061] In some embodiments, the target tracking focusing method further includes:

[0062] When tracking multiple targets using an infrared optical system, the sharpness of each sub-image region related to the multiple targets is determined; then, the sharpness of each sub-image region is weighted; and finally, the focusing parameters of the infrared optical system are determined based on the weighted result. Specifically, focusing can be performed by weighting the sharpness of multiple targets relative to the surrounding background. This ensures that multiple targets maintain good sharpness in the acquired infrared image.

[0063] In other embodiments, the target tracking focusing method further includes: scanning and recording the position information of each target; and, when a target appears, adjusting the focus based on the target's position information and determined focusing parameters. Specifically, a servo system can be controlled to scan and record the positions of multiple targets. During the scanning process, when a target appears, the focusing value of the previous position is read to control the focusing motor, thereby achieving focusing and adjusting the sharpness of the target in real time, thus improving the tracking stability of extreme targets.

[0064] In some embodiments, the target tracking focusing method further includes: configuring initial tracking parameters of the infrared optical system according to the tracking environment; and tracking the target based on the initial tracking parameters. That is, when target tracking is required, an initial focal length can first be set according to commonly used illumination, target distance, and background depth. This initiates the initial tracking state, and then the aforementioned focusing method is further used to focus the tracked target, thereby improving the maximum detection and tracking distance.

[0065] In some embodiments, the target tracking focusing method further includes:

[0066] A user interface is provided, through which the focusing parameters are presented to the user based on the infrared image data. In other words, the real-time local sharpness of the target and the target distance can be displayed on a visual user interface to assist operators in judging the focusing quality of the target.

[0067] This disclosure further presents implementation examples of the target focusing method, such as... Figure 3 As shown, it includes the following steps:

[0068] Step S301: Set the initial focal length using environmental and target parameters, and acquire infrared images at this focal length. Display the real-time local sharpness and target distance of the target on a visual interface to assist operators in judging the focusing quality of the target.

[0069] Step S302: Perform target detection. When switching to target tracking mode, track the target using a target tracking and detection algorithm to fix the target in a preset area.

[0070] Step S303: Calculate the local sharpness parameters of each current frame of infrared image in real time. In order to improve the real-time performance of the system, the sharpness parameters can be selected based on the local contrast with the lowest computational cost. The neighborhood range of the target can be 20*20 pixels.

[0071] Step S304: Make positive and negative fine adjustments to the target based on sharpness, and stop focusing when the sharpness peak is reached.

[0072] Step S305: Use tracking algorithms such as Kalman filtering or kernel correlation filtering to predict the distance change of the target relative to the photoelectric device, and the focusing direction can be estimated in advance.

[0073] Step S306: Display the real-time target local sharpness parameters or other focusing quality indicators, target distance, and real-time infrared image on the visualization interface.

[0074] When the distance changes, the S303-S306 operations are executed repeatedly until the target is lost, at which point target detection is performed or the user selects another image processing algorithm.

[0075] When there are multiple targets of interest, the local sharpness of the multiple targets is weighted to determine the stopping position of the motor focusing.

[0076] The method disclosed herein enables real-time focusing of the tracked target, reducing the need for subjective human judgment during flight, minimizing manual focusing, simplifying operation, and improving flight safety.

[0077] The method and image acquisition device for real-time focusing on a tracking target proposed in this invention can achieve rapid focusing, advance target detection time, delay target loss events, and achieve first-strike capability. Furthermore, the focusing method of this embodiment can improve the difference in radiation intensity between the target and the background without changing the target detection and tracking algorithm, thereby improving the target's signal-to-noise ratio. Since the focusing accuracy of the human eye is greater than ±2µm, while automatic machine focusing can control the focusing accuracy to the minimum scale of the focusing motor, the focusing accuracy is greatly improved, enhancing the tracking stability of extreme targets. The method of this embodiment can also verify the specific effective focal values ​​of targets at different distances, thereby generating a distance-focus database. In practical use, the method disclosed herein can achieve real-time rapid focusing on aerial targets at distances ranging from 1km to 100km. Therefore, the method disclosed herein also effectively improves the maximum detection and tracking distance of targets.

[0078] The present invention also proposes a target tracking focusing device, including a memory, a processor, and a computer program stored in the memory and executable on the processor. When the computer program is executed by the processor, it implements the steps of the target tracking focusing method described in the embodiments of the present disclosure.

[0079] The present invention also proposes a computer-readable storage medium storing a computer program, which, when executed by a processor, implements the steps of the target tracking and focusing method described in the embodiments of the present disclosure.

[0080] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element.

[0081] The sequence numbers of the above embodiments of the present invention are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0082] Through the above description of the embodiments, those skilled in the art can clearly understand that the methods of the above embodiments can be implemented by means of software plus necessary general-purpose hardware platforms. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation method. Based on this understanding, the technical solution of the present invention, or the part that contributes to the prior art, can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions to cause a terminal (which may be a mobile phone, computer, server, or network device, etc.) to execute the methods described in the various embodiments of the present invention.

[0083] The embodiments of the present invention have been described above with reference to the accompanying drawings. However, the present invention is not limited to the specific embodiments described above. The specific embodiments described above are merely illustrative and not restrictive. Those skilled in the art can make many other forms under the guidance of the present invention without departing from the spirit and scope of the claims. All of these forms are within the protection scope of the present invention.

Claims

1. A method of tracking a target focus, characterized by, Comprising: In a state of tracking a target by using an infrared optical system, the target is farther and farther away from an optical receiving window, the farthest distance being a point target, and infrared image data of tracking the point target is acquired based on the infrared optical system; A definition parameter of a sub-image region related to the target in the infrared image data is determined; A focusing parameter of the infrared optical system is determined based on the definition parameter of the sub-image region; A variation of a distance between the target and the infrared optical system is determined based on Kalman filtering; The infrared optical system is focused by using the focusing parameter, including: the infrared optical system is focused according to the variation of the distance and the definition of the sub-image region; and the focusing is ended when a required definition is reached; The infrared image data is acquired by an infrared detector receiving radiation of the infrared optical system; The definition parameter of the sub-image region related to the target in the infrared image data is determined by: A target neighborhood range of a preset size in the infrared image data is taken as the sub-image region; The definition parameter of the sub-image region is calculated.

2. The tracking target focusing method of claim 1, wherein, The definition parameter of the sub-image region is calculated by using one of the following methods: gradient contrast method, definition variance, multi-frame gray scale change contrast, and wavelet transform of the infrared image.

3. The tracking target focusing method of claim 1, wherein, The tracking target focusing method further comprises: In a case of tracking multiple targets by using the infrared optical system, definitions of multiple sub-image regions related to the multiple targets are determined; The definitions of the multiple sub-image regions are weighted; The focusing parameter of the infrared optical system is determined based on the weighting result.

4. The tracking target focusing method of claim 3, wherein, The tracking target focusing method further comprises: Position information of each target is scanned and recorded; In a case of appearance of the target, the target is focused based on the position information of the target and the determined focusing parameter.

5. The tracking target focusing method of claim 1, wherein, The tracking target focusing method further comprises: An initial tracking parameter of the infrared optical system is configured according to a tracking environment; The target is tracked based on the initial tracking parameter.

6. The tracking target focusing method of claim 1, wherein, The tracking target focusing method further comprises: A user interface is provided, and the focusing parameter is presented to a user based on the infrared image data through the user interface.

7. A tracking target focusing device, characterized by, A computer readable storage medium stores a computer program, and the computer program is executed by a processor to implement steps of the tracking target focusing method according to any one of claims 1 to 6.

8. A computer-readable storage medium, characterized in that, The computer readable storage medium stores a computer program, and the computer program is executed by a processor to implement steps of the tracking target focusing method according to any one of claims 1 to 6.

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