Infrared image enhancement method and device for omnidirectional infrared search and tracker

Abstract

The present invention discloses an image enhancement method for an omnidirectional infrared search tracker, which generates a corresponding grayscale mapping function based on each frame of infrared image of the current circle collected by the omnidirectional infrared search tracker; and generates a corresponding grayscale mapping function based on each frame of infrared image of the current circle to map the infrared image of the corresponding frame of the next circle of the current circle collected by the omnidirectional infrared search tracker. The present invention also provides an image enhancement device for an omnidirectional infrared search tracker. The present invention can quickly, in real time, and accurately enhance the infrared images collected by the omnidirectional infrared search tracker, so that the output image details and order are clearer; it is convenient for users to observe; at the same time, the method provided by the present invention has a small amount of calculation, low hardware requirements, and effectively reduces the cost of use.

Description

Technical Field

[0001] The invention belongs to the field of infrared image processing, and in particular relates to an image enhancement method for an omnidirectional infrared search tracker. Background Art

[0002] Infrared search and tracking integrates infrared imaging, laser ranging, high-speed image information processing and precision servo control technologies. It is mainly used to provide air defense weapon systems with air target search, tracking, positioning and target indication. Infrared search and tracking consists of an optical system, infrared detector components, circuits and housings, and achieves 360° azimuth tracking through the rotation of the common turntable controlled by the host computer.

[0003] The FPGA implementation method of the traditional detector platform histogram equalization can use the mapping relationship of the previous frame for the current frame image, which results in a delay. Traditional detectors generally detect at fixed positions, while the detectors used in search and tracking devices need to achieve 360° azimuth rotation. There will be a large deviation when using the previous frame of data image, and the output image after processing will have changes in brightness, resulting in less clear details and order in the processed image. The traditional platform histogram equalization FPGA implementation is not suitable for use in search and tracking devices. Summary of the invention

[0004] Purpose of the invention: In view of the problems existing in the prior art, the present invention proposes an image enhancement method for an omnidirectional infrared search tracker which has good processing effect, fast processing speed and is more suitable for omnidirectional infrared search and tracking.

[0005] Technical solution: To achieve the above-mentioned purpose, the present invention provides an image enhancement method for an omnidirectional infrared search tracker, which generates a corresponding grayscale mapping function according to each frame of infrared image of the current circle collected by the omnidirectional infrared search tracker;

[0006] A corresponding grayscale mapping function is generated according to each frame of infrared image of the current circle to map the infrared image of the corresponding frame of the next circle of the current circle collected by the omnidirectional infrared search tracker.

[0007] Further, the grayscale mapping function generation method comprises the following steps:

[0008] Step 101: Count the grayscale histogram H of the mth frame of the infrared image in the nth cycle nm ,for:

[0009]

[0010] Among them, k represents the number of gray levels, It represents the number of pixels with gray level k in the m-th frame infrared image in the n-th circle; L represents the number of bits of the infrared image collected by the omnidirectional infrared search tracker.

[0011] Step 102: Count the gray level k to obtain the gray cumulative histogram distribution value cdf k , and mapped to the specified grayscale space to obtain the grayscale mapping function s nm (k);

[0012]

[0013]

[0014] Among them, cdf max is the maximum value of the grayscale cumulative histogram distribution, and S represents the number of bits of the output infrared image. This method can reduce the bit size of the output image while ensuring the quality of the output image, meet the display conditions of the terminal, and facilitate users to observe through the terminal.

[0015] Further, the grayscale mapping function generation method comprises the following steps:

[0016] Step 101: Count the grayscale histogram H of the mth frame of the infrared image in the nth cycle nm ,for:

[0017]

[0018] Among them, k represents the number of gray levels, It represents the number of pixels with gray level k in the m-th frame infrared image in the n-th circle; L represents the number of bits of the infrared image collected by the omnidirectional infrared search tracker.

[0019] Step 102: According to the clipping threshold ClipLimit, clipping is performed on the portion of the grayscale histogram that exceeds the threshold;

[0020]

[0021] In the formula, H′ nm (k) is the grayscale histogram after cropping; one or two cropping can be performed according to the needs;

[0022] Step 103: The cropped grayscale histogram H′ nm (k) is processed and the gray level cumulative histogram distribution value cdf of the gray level k is counted k , and mapped to the specified grayscale space to obtain the grayscale mapping function s nm (k);

[0023]

[0024]

[0025] in, represents the number of pixels with gray level k in the gray histogram after cropping the m-th frame of infrared image in the n-th circle; cdf max is the maximum value of the grayscale cumulative histogram distribution, and S represents the number of bits of the output infrared image. In the process of generating the grayscale mapping function, the grayscale histogram is clipped to better increase the image contrast.

[0026] Furthermore, each frame of infrared image generates a grayscale mapping function and specifically includes the following steps:

[0027] S1: Detect the frame signal of the current frame infrared image, and if detected, the frame counter is incremented by one; find the corresponding grayscale mapping function in the memory according to the value in the frame counter; when the value in the frame counter reaches the frame number threshold, it is cleared and the counting starts again;

[0028] S2: Starting from the detection of the frame signal of the current frame infrared image, after the set time interval △t2, the current frame infrared image begins to be processed line by line; during the processing time of each line, the number of pixels of each gray level in the corresponding line of the input current frame infrared image is counted; at the same time, according to the corresponding gray mapping function found in S1, each pixel value in the corresponding line of the input current frame infrared image is mapped to complete the image enhancement of the corresponding line;

[0029] S3: After the last line of the infrared image of the current frame is processed, the enhanced image is directly output; at the same time, the grayscale histogram statistics of the infrared image of the current frame are completed; the grayscale mapping function of the infrared image of the current frame is generated according to the histogram equalization method; and the generated grayscale mapping function and the value in the corresponding frame counter are stored in the memory;

[0030] S4: Repeat S1 to S3 until the omnidirectional infrared search tracker stops working. This can achieve image enhancement stably and quickly, and can effectively deliver image enhancement effects.

[0031] Furthermore, the preferred range of the time interval Δt2 is: one-row processing time < Δt2 < two-row processing time; wherein the processing time of each row is the product of the number of pixels in each row of the current frame infrared image and the pixel clock.

[0032] The present invention also provides an image enhancement device for an omnidirectional infrared search tracker, comprising a processor and a memory, namely a terminal;

[0033] The processor generates a corresponding grayscale mapping function according to each frame of infrared image of the current circle collected by the omnidirectional infrared search tracker, and stores it in the memory;

[0034] The infrared image of the corresponding frame of the next circle of the current circle collected by the omnidirectional infrared search tracker is mapped according to the corresponding grayscale mapping function generated by each frame of the infrared image of the current circle in the memory, and output to the terminal.

[0035] Furthermore, the memory is a dual-port RAM.

[0036] Furthermore, the processor and memory are embedded and arranged in the omnidirectional infrared search tracker.

[0037] The present invention also provides a computer-readable medium storing software, wherein the software includes instructions that can be executed by one or more computers, and the instructions, through such execution, cause the one or more computers to perform operations, and the operations include the process of the aforementioned image enhancement method for an omnidirectional infrared search tracker.

[0038] According to another aspect of the present invention, there is also provided a computer system, comprising:

[0039] one or more processors;

[0040] A memory stores operable instructions, wherein when the instructions are executed by the one or more processors, the one or more processors are caused to perform operations, wherein the operations include the process of the image enhancement method for an omnidirectional infrared search tracker as described above.

[0041] Significant beneficial effects:

[0042] Compared with the prior art, the present invention can quickly, in real time and accurately enhance the infrared images collected by the omnidirectional infrared search and tracker, making the output image details and texture clearer and more convenient for users to observe. At the same time, the method provided by the present invention has a small amount of calculation and low hardware requirements, which effectively reduces the cost of use. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 A schematic diagram of the flow of the image enhancement method for the omnidirectional infrared search tracker provided by the present invention;

[0044] Figure 2 A schematic diagram of a clock signal in the method provided by the present invention. DETAILED DESCRIPTION

[0045] The following will be combined with the accompanying drawings in the examples of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0046] This embodiment provides an image enhancement device for an omnidirectional infrared search tracker, which mainly includes a processor, a memory and a terminal; the processor and the memory can be embedded and directly set inside the infrared search tracker, or can exist independently.

[0047] In this embodiment, the infrared search tracker is set on the common frame turntable, and the 360° full-angle infrared image acquisition is achieved by controlling the rotation of the common frame turntable. When it is necessary to complete the tracking and search of the target, the infrared search tracker needs to continuously rotate the common frame turntable to collect infrared images of the surrounding environment; the processor mainly performs enhancement processing on the image collected by the infrared search tracker, and then displays it through the terminal device, wherein the enhancement processing method for the image collected by the infrared search tracker is mainly based on histogram equalization.

[0048] like Figure 1 As shown, as an optional example, the image enhancement device of the omnidirectional infrared search tracker, its enhancement process mainly includes generating a corresponding grayscale mapping function for each frame of infrared image in the current circle, and using it to map each frame of infrared image in the next circle of the current circle.

[0049] Next, we describe an exemplary implementation of the above process with reference to specific examples.

[0050] Step 1: Generate the corresponding grayscale mapping function s according to each frame of infrared image of the current circle collected by the omnidirectional infrared search tracker nm (k), the grayscale mapping function sequence S that constitutes the current circle n [s n1 (k), s n2 (k), ..., s nm (k), ..., s nM (k)] is stored in the memory.

[0051] Among them, s nm (k) represents the grayscale mapping function generated by the m-th infrared image frame collected in the n-th rotation of the omnidirectional infrared search tracker; n represents the number of rotations of the omnidirectional infrared search tracker, m represents the number of infrared images in each rotation; M represents the total number of infrared images collected in each rotation, and k represents the number of gray levels.

[0052] Among them, the corresponding grayscale mapping function s is generated nm The method is:

[0053] Step 101: Count the grayscale histogram H of the mth frame of the infrared image in the nth cycle nm , since the grayscale histogram of the image is a one-dimensional discrete function, it is recorded as:

[0054]

[0055] Among them, k represents the number of gray levels, It represents the number of pixels with gray level k in the m-th frame infrared image in the n-th circle, that is, the height of each column of the histogram corresponds to L represents the number of bits of the infrared image collected by the omnidirectional infrared search and tracker. The infrared image collected by the omnidirectional infrared search and tracker used in this embodiment is 14 bits.

[0056] Step 102: According to the clipping threshold ClipLimit, clipping is performed on the portion of the grayscale histogram that exceeds the threshold;

[0057]

[0058] In the formula, H′ nm (k) is the grayscale histogram after cropping; one or two cropping can be performed according to the needs;

[0059] Step 103: The cropped grayscale histogram H′ nm (k) is processed, and the gray level k is counted to obtain the gray cumulative histogram distribution value cdf k , and mapped to the specified grayscale space to obtain the grayscale mapping function s nm (k);

[0060]

[0061]

[0062] in, represents the number of pixels with gray level k in the gray histogram after cropping the m-th frame of infrared image in the n-th circle, i represents the gray level number; cdf max is the maximum value of the grayscale cumulative histogram distribution, that is, all cdf k S represents the number of bits of the output infrared image. In this embodiment, the number of bits of each frame of the output image is 8 bits.

[0063] Step 2: Each frame of the infrared image of the next circle of the current circle is s according to the grayscale mapping function sequence corresponding to the number of the current circle. nm Mapping is performed and the mapped image is output to the terminal; at the same time, the grayscale mapping function sequence S of the current circle is completed according to the method provided in step 1 n+1 generated and stored.

[0064] Repeat steps 1 and 2 until the infrared search and tracker stops working.

[0065] The method provided in this embodiment mainly uses a grayscale mapping function generated by each frame of infrared image collected by the omnidirectional infrared search tracker in the previous circle to enhance the infrared image of the corresponding frame collected by the omnidirectional infrared search tracker in the next circle; and generates a new grayscale mapping function for use in the next circle of the current circle.

[0066] In this way, the image can be effectively enhanced, the details and texture of the output image can be made clearer, and the phenomenon of light and dark changes can be avoided. In this embodiment, the 14-bit image collected by the omnidirectional infrared search tracker is downgraded, so that the 14-bit image is downgraded to an 8-bit image for output, which is more conducive to terminal display.

[0067] In this embodiment, a method for implementing an enhancement processing method for an image collected by an infrared search tracker is provided, wherein the pixel clock is 50Mhz, the frame rate is 100HZ, the resolution of the image collected by the infrared search tracker is 640×512, and the timing diagram of each frame image processing is as follows: Figure 2 As shown, specifically including:

[0068] S1: When the falling edge of the frame signal is detected, the frame counter is incremented by one; then the corresponding grayscale mapping function is found in the memory according to the value in the frame counter; when the value in the frame counter reaches the frame number threshold, it is cleared and the counting starts again; the frame number threshold is the total number of infrared images collected by the infrared search tracker when it rotates one circle.

[0069] S2: Starting from the falling edge of the frame signal, until the set time interval △t2 has passed, the image collected by the infrared search tracker begins to be processed line by line; during the processing time of each line, two things are mainly processed: one is to count the number of pixels of each gray level in the line of the input original image; the other is to map each pixel value in the line of the input original image according to the corresponding gray mapping function found in S1, and complete the image enhancement of the corresponding line; the two things are carried out in parallel;

[0070] S3: When the last line of the image collected by the infrared search tracker is processed, the enhanced image is directly output; at the same time, the grayscale histogram statistics of the original image of the current frame are completed; the grayscale mapping function of the current frame image is generated according to the above-mentioned grayscale mapping function generation method; and the generated grayscale mapping function and the corresponding frame counter value are stored in the memory.

[0071] Among them, when the falling edge of the frame signal of the next frame arrives, S1~S3 must be completed, and S1~S3 are repeated according to the frame signal of each frame image until the infrared search tracker stops collecting; S1 needs to be completed within the set time interval △t2, and the preferred range of △t2 is: one line processing time <△t2 < two lines processing time. In this embodiment, the image resolution collected by the infrared search tracker is 640×512, so the processing time of one line is 640 pixel clocks, and the processing time of two lines is 1280 pixel clocks. In the figure, △t is the invalid time of the line, and △t is the time interval between the direct output of the image after the enhancement processing and the generation and storage of the grayscale mapping function. The memory used to store the grayscale mapping function sequence in this embodiment is a dual-port RAM. This method can quickly and effectively realize image enhancement, and the user can view the enhanced image in real time through the terminal.

[0072] The present invention also provides a computer-readable medium storing software, wherein the software includes instructions that can be executed by one or more computers, and the instructions, through such execution, enable the one or more computers to perform operations, and the operations include the process of the image enhancement method for an omnidirectional infrared search tracker as described above.

[0073] The present invention also provides a computer system, comprising: one or more processors; a memory, storing operable instructions, wherein when the instructions are executed by the one or more processors, the one or more processors perform operations, wherein the operations include the process of the image enhancement method for an omnidirectional infrared search tracker as described above.

[0074] It should be understood that the aforementioned example of the image enhancement method for an omnidirectional infrared search tracker of the present invention can be used in any computer system that includes data storage and data processing, and the aforementioned computer system can be at least one electronic processing system or electronic device including a processor and a memory, such as a PC, whether it is a personal PC, a commercial PC, or a PC for graphics processing, or a server-level PC. These PCs can realize wired and / or wireless data transmission, especially image data, by having a data interface and / or a network interface.

[0075] In other embodiments, the computer system may also be a server, especially a cloud server, having data storage, processing and network communication functions.

[0076] An exemplary computer system generally includes at least one processor, a memory, and a network interface connected by a system bus. The network interface is used to communicate with other devices / systems.

[0077] The processor is used to provide computation and control of the system.

[0078] The memory includes non-volatile memory and cache.

[0079] The non-volatile memory generally has a mass storage capacity and can store an operating system and computer programs. These computer programs may include operable instructions that, when executed by one or more processors, enable the one or more processors to perform the process of the image enhancement method for an omnidirectional infrared search tracker of the aforementioned embodiment of the present invention.

[0080] In necessary or reasonable implementations, the aforementioned computer system, whether a PC device or a server, may also include more or fewer components than those shown in the diagram, or a combination, or use different hardware, software or other components or different deployment methods.

Claims

1. An image enhancement method for an omnidirectional infrared search tracker, characterized in that: Generate a corresponding grayscale mapping function according to each frame of infrared image of the current circle collected by the omnidirectional infrared search tracker; Mapping the infrared image of the next circle corresponding to the frame of the current circle collected by the omnidirectional infrared search tracker according to the corresponding grayscale mapping function generated by each frame of the infrared image of the current circle; Each frame of infrared image generates a grayscale mapping function and specifically includes the following steps: S1: Detect the frame signal of the current frame infrared image, and if detected, the frame counter is incremented by one; find the corresponding grayscale mapping function in the memory according to the value in the frame counter; when the value in the frame counter reaches the frame number threshold, it is cleared and the counting starts again; S2: Starting from the detection of the frame signal of the current frame infrared image, after the set time interval △t2, the current frame infrared image begins to be processed line by line; during the processing time of each line, the number of pixels of each gray level in the corresponding line of the input current frame infrared image is counted; at the same time, according to the corresponding gray mapping function found in S1, each pixel value in the corresponding line of the input current frame infrared image is mapped to complete the image enhancement of the corresponding line; S3: After the last line of the infrared image of the current frame is processed, the enhanced image is directly output; at the same time, the grayscale histogram statistics of the infrared image of the current frame are completed; the grayscale mapping function of the infrared image of the current frame is generated according to the histogram equalization method; and the generated grayscale mapping function and the value in the corresponding frame counter are stored in the memory; S4: Repeat S1 to S3 until the omnidirectional infrared search and tracker stops working.

2. The image enhancement method for an omnidirectional infrared search tracker according to claim 1, characterized in that: The grayscale mapping function generation method comprises the following steps: Step 101: Count the grayscale histogram H of the mth frame of the infrared image in the nth cycle nm ,for: Among them, k represents the number of gray levels, represents the number of pixels with gray level k in the m-th frame infrared image in the n-th circle; L represents the number of bits of the infrared image collected by the omnidirectional infrared search tracker; Step 102: Count the grayscale cumulative histogram distribution value cdf of grayscale level k k , and mapped to the specified grayscale space to obtain the grayscale mapping function s nm (k); Among them, cdf max is the maximum value of the grayscale cumulative histogram distribution, and S represents the number of bits of the output infrared image.

3. The image enhancement method for an omnidirectional infrared search tracker according to claim 1, characterized in that: The grayscale mapping function generation method comprises the following steps: Step 101: Count the grayscale histogram H of the mth frame of the infrared image in the nth cycle nm ,for: Among them, k represents the number of gray levels, represents the number of pixels with gray level k in the m-th frame infrared image in the n-th circle; L represents the number of bits of the infrared image collected by the omnidirectional infrared search tracker; Step 102: According to the clipping threshold ClipLimit, clipping is performed on the portion of the grayscale histogram that exceeds the threshold; In the formula, H′ nm (k) is the grayscale histogram after cropping; one or two cropping can be performed according to the needs; Step 103: The cropped grayscale histogram H′ nm (k) is processed, and the gray level k is counted to obtain the gray cumulative histogram distribution value cdf k , and mapped to the specified grayscale space to obtain the grayscale mapping function s nm (k); Among them, H′ nm (i) represents the number of pixels with gray level i in the gray histogram after cropping the m-th frame of infrared image in the n-th circle; cdf max is the maximum value of the grayscale cumulative histogram distribution, and S represents the number of bits of the output infrared image.

4. The image enhancement method for an omnidirectional infrared search tracker according to claim 1, characterized in that: The range of the time interval Δt2 is: one-row processing time<Δt2<two-row processing time; wherein the processing time of each row is the product of the number of pixels in each row of the current frame infrared image and the pixel clock.

5. An image enhancement device for an omnidirectional infrared search and tracker, characterized in that: Includes processor, memory and terminal; The processor generates a corresponding grayscale mapping function according to each frame of infrared image of the current circle collected by the omnidirectional infrared search tracker, and stores it in the memory; The infrared image of the corresponding frame of the next circle of the current circle collected by the omnidirectional infrared search tracker is mapped according to the corresponding grayscale mapping function generated by each frame of the infrared image of the current circle in the memory, and output to the terminal; The grayscale mapping function for each frame of infrared image is generated and specifically includes the following steps: S1: Detect the frame signal of the current frame infrared image, and if detected, the frame counter is incremented by one; find the corresponding grayscale mapping function in the memory according to the value in the frame counter; when the value in the frame counter reaches the frame number threshold, it is cleared and the counting starts again; S2: Starting from the detection of the frame signal of the current frame infrared image, after the set time interval △t2, the current frame infrared image begins to be processed line by line; during the processing time of each line, the number of pixels of each gray level in the corresponding line of the input current frame infrared image is counted; at the same time, according to the corresponding gray mapping function found in S1, each pixel value in the corresponding line of the input current frame infrared image is mapped to complete the image enhancement of the corresponding line; S3: After the last line of the infrared image of the current frame is processed, the enhanced image is directly output; at the same time, the grayscale histogram statistics of the infrared image of the current frame are completed; the grayscale mapping function of the infrared image of the current frame is generated according to the histogram equalization method; and the generated grayscale mapping function and the value in the corresponding frame counter are stored in the memory; S4: Repeat S1 to S3 until the omnidirectional infrared search and tracker stops working.

6. The image enhancement device for an omnidirectional infrared search and tracker according to claim 5, characterized in that: The memory is a dual-port RAM.

7. The image enhancement device for an omnidirectional infrared search and tracker according to claim 5, characterized in that: The processor and the memory are embedded and arranged in the omnidirectional infrared search tracker.

8. A computer-readable medium storing software, characterized in that: The software includes instructions that can be executed by one or more computers, and the instructions, through such execution, cause the one or more computers to perform operations, and the operations include the process of the image enhancement method for an omnidirectional infrared search tracker as described in any one of the preceding claims 1-4.

9. A computer system, characterized in that: include: one or more processors; A memory storing operable instructions, wherein when the instructions are executed by the one or more processors, the one or more processors are caused to perform operations, wherein the operations include the process of the image enhancement method for an omnidirectional infrared search tracker as described in any one of claims 1 to 4.

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