Extraction method of overexposure grating diffraction laser spot image

Abstract

According to the overexposure grating diffraction laser spot image extraction method provided by the invention, multi-scale expansion and corrosion operation is adopted, so that large-area highlight operation is processed for an exposure image, background noisy points can be filtered out, useful information of diffraction spots can be reserved, useful spot information is distinguished from other information, and the image extraction efficiency is improved. Convenience is provided for a rear end to continue to recognize light spot information, and the problem of mixed distinguishing of laser captured by a photoelectric detector and stray light under the condition that laser energy is too high is solved; in other words, stray light and noise light signals mixed in the original image are subjected to expansion corrosion and other preprocessing before the light spot image is processed, and the processing difficulty of a rear-end circuit and the design complexity can be reduced; a light spot image is more clearly divided from a preprocessed grating diffraction type laser light spot image in an exposure state, and subsequent laser point location extraction is carried out so as to identify the wavelength type of laser.

Description

Technical Field

[0001] This invention belongs to the field of image processing technology, and in particular relates to a method for extracting images of overexposed grating diffraction laser spots. Background Technology

[0002] Laser recognition technology is primarily used to measure laser signal information illuminating the photosensitive surface of detector devices. In deep space exploration, photosensitive devices are mounted on deep-space spacecraft to receive laser signals pointed at by targets in deep space. Upon receiving the external target's pointing signal, the photosensitive device processes the laser image, identifies the laser spot signal, and uses this information to control the linkage of the deep-space probe's back-end circuitry, activating the spacecraft's protection mechanisms to prevent attacks from external devices. During the identification of the laser spot signal, if the incoming laser energy is too high, it can cause overexposure in the acquired laser spot image, introducing stray light interference that affects the direct processing of the laser image. Summary of the Invention

[0003] To address the aforementioned problems, this invention provides a method for extracting laser spot images from overexposed grating diffraction. This method is used for preprocessing laser spot images, enabling the processed images to be directly used for spot image segmentation, thereby achieving the effect of laser point extraction.

[0004] A method for extracting laser spot images from overexposed grating diffraction includes the following steps: Step S1: Obtain an image of the laser spot with overexposed original grating diffraction; Step S2: Perform one-dimensional thresholding on the original overexposed laser spot image of the grating diffraction to obtain the segmentation threshold. ; Step S3: Based on segmentation threshold Binarization processing is performed on the overexposed laser spot image; Step S4: Perform a first dilation process on the binarized image using circular structuring elements. The first dilation process is used to enhance the circular light spot and filter out salt-and-pepper noise in the image. Step S5: Perform a second dilation process on the image after the first dilation process using a cross-shaped structuring element. The second dilation process is used to enhance the circular light spot and filter out band noise in non-horizontal and non-vertical directions. Step S6: Perform a third dilation process on the image after the second dilation process using the star-shaped structuring element. The second dilation process is used to enhance the circular light spot and filter out the horizontal and vertical band noise. Step S7: Use rectangular structural elements to perform erosion processing on the image after the third dilation process to obtain the final processed image. The erosion processing is used to uniformly expand the circular light spot.

[0005] Furthermore, the pixel values ​​at each pixel point in the image after one-dimensional thresholding are:

[0006] in, This indicates the position of the image after one-dimensional thresholding. pixel values, This represents the threshold parameter obtained from one-dimensional threshold segmentation.

[0007] Furthermore, the circular structural element R1 is as follows: .

[0008] Furthermore, the cross-shaped structural element R2 is as follows: .

[0009] Furthermore, the rice-shaped structural element R3 is as follows: .

[0010] Furthermore, the rectangular structural element R4 is as follows: .

[0011] Beneficial effects: This invention provides a method for extracting overexposed grating diffraction laser spot images. It employs multi-scale dilation and erosion operations to address large-area high-brightness operations in exposed images. This method filters out background noise while preserving useful information from the diffraction spots, distinguishing the useful spot information from other information. This facilitates subsequent spot information identification and solves the problem of photodetectors capturing and distinguishing between mixed laser and stray light when laser energy is too high. In other words, this invention preprocesses the stray light and noise signals mixed in with the original image through dilation and erosion before processing the spot image, reducing the difficulty and complexity of subsequent circuit processing. The preprocessed grating diffraction laser spot image under exposed conditions more clearly delineates the spot image, allowing for subsequent extraction of laser points to identify the laser wavelength type. Attached Figure Description

[0012] Figure 1 A schematic flowchart of a method for extracting laser spots from overexposed grating diffraction provided by the present invention; Figure 2 The present invention provides an image of a grating diffraction laser spot exposure obtained by a photosensitive detector. Figure 3 This invention provides an exposure image of a grating diffraction laser spot after multi-scale expansion corrosion processing. Detailed Implementation

[0013] To enable those skilled in the art to better understand the present application, the technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings.

[0014] This invention provides a method for extracting laser spot images from overexposed grating diffraction, such as... Figure 1 As shown, it includes the following steps: Step S1: Obtain an image of the laser spot with overexposed original grating diffraction, such as... Figure 2 As shown; It should be noted that the overexposed laser spot image after grating diffraction transforms from an original single spot into multiple scattered spots, and the positional size difference between adjacent scattered spots shows a regular arrangement. Therefore, the laser wavelength type can be inverted based on the size difference between adjacent scattered spots.

[0015] Meanwhile, the method for obtaining overexposed laser spot images is as follows: A laser grating diffraction system is constructed, consisting of a laser source, lens, grating, photodetector, and back-end processing circuitry. Excessively high-energy laser light passes sequentially through the lens and grating, illuminating the detector target surface to obtain the original overexposed laser spot image from the grating diffraction.

[0016] Step S2: Perform one-dimensional thresholding on the original overexposed laser spot image of the grating diffraction to obtain the segmentation threshold. ; Step S3: Based on segmentation threshold Binarization processing is performed on the overexposed laser spot image; The pixel values ​​of each pixel in the image after one-dimensional threshold segmentation are:

[0017] in, This indicates the position of the image after one-dimensional thresholding. pixel values, This represents the threshold parameter obtained from one-dimensional threshold segmentation. The binarization method is as follows: The pixel value at point index is greater than the threshold parameter index, so the pixel value at that point becomes 1. If the pixel value at a given point is less than or equal to the threshold parameter index, the pixel value at that point becomes 0.

[0018] Step S4: Perform a first dilation process on the binarized image using circular structuring elements. The first dilation process is used to enhance the circular light spot and filter out salt-and-pepper noise in the image. The circular structural element R1 is as follows:

[0019] In other words, this invention uses circular structuring elements to sequentially perform sliding dilation operations on 7×7 regions centered on each pixel of the image processed in step S3, without changing the dimensions of the original overall image. Assuming the image processed in step S3 is C, the image processed by the R1 structuring element is C = C⊕R1, where ⊕ represents the dilation operation.

[0020] It should be noted that after binarization processing, the image information based on the original grating diffraction overexposed laser spot image presents the main element as a circular spot, and the secondary elements as salt-and-pepper noise and band noise. Circular structuring elements can be used to match the main element, retain the circular spot, and filter out most of the secondary elements. That is, a large amount of scattered salt-and-pepper noise and band noise are filtered out. After this step, an image with the main element as a circular spot and a small amount of band noise is obtained.

[0021] Step S5: Perform a second dilation process on the image after the first dilation process using a cross-shaped structuring element. The second dilation process is used to enhance the circular light spot and filter out band noise in non-horizontal and non-vertical directions. The cross-shaped structural element R2 is as follows:

[0022] It should be noted that the image processed in step S4 filters out the scattered salt-and-pepper noise and compresses the size of the original banded noise, but does not completely remove it. Step S5 uses a cross-shaped structuring element to filter out the size-compressed banded noise. The cross-shaped structuring element processes the image processed in step S4 along the horizontal and vertical directions. Since the banded noise exhibits non-directional strip-like characteristics, the cross-shaped structuring element is used to expand and filter out the banded noise in the non-horizontal and non-vertical directions, while retaining the main element light spot of the image information. After this step, an image with the main element circular light spot and a small amount of horizontal and vertical banded noise is obtained.

[0023] Meanwhile, the operation of the structuring element does not change the dimensions of the original image. Here, a cross-shaped structuring element is used to slide sequentially across a 5×5 region centered on each pixel of the image processed in step S4, and the dimensions of the original overall image remain unchanged. Assuming the image after step S4 is C, the image after processing with the R2 structuring element is C = C⊕R2.

[0024] Step S6: Perform a third dilation process on the image after the second dilation process using the star-shaped structuring element. The second dilation process is used to enhance the circular light spot and filter out the horizontal and vertical band noise. The rice-shaped structural element R3 is as follows:

[0025] It should be noted that the image processed in step S5 has filtered out non-horizontal and non-vertical band noise, but the horizontal and vertical band noise has not been removed. The star-shaped structural element processes the image processed in step S5 along the non-horizontal and non-vertical direction to filter out the non-horizontal and non-vertical band noise. The image obtained at this time is a diffraction laser spot image with salt-and-pepper noise removed.

[0026] Meanwhile, the operation of structuring elements does not change the dimensions of the original image. Here, a star-shaped structuring element is used to slide sequentially across a 3×3 region centered on each pixel of the image processed in step S5, and the dimensions of the original overall image remain unchanged. Assuming the image processed in step S5 is C, the image after dilation processing with the R3 structuring element is C = C⊕R3.

[0027] Step S7: Use rectangular structuring elements to perform erosion processing on the image after the third dilation process to obtain the final processed image. The erosion process is used to uniformly expand the circular light spot, such as... Figure 3 As shown.

[0028] The rectangular structural element R4 is as follows:

[0029] It should be noted that the operations on structuring elements do not change the dimensions of the original image. Here, a rectangular structuring element is used to slide sequentially across a 5×5 region centered on each pixel of the image processed in step S6. The dimensions of the original overall image remain unchanged. Let the image after step S6 be C. The image after R4 structuring element erosion is C=C. R4.

[0030] As can be seen, the diffraction laser spot image after steps S4, S5, and S6 removes salt-and-pepper noise and band noise, but at the same time, the effective spot size is also compressed. Step S7 uses rectangular structuring element erosion. The rectangular structuring element uniformly expands the regular-shaped spot, presenting the effect of increasing the spot size, which is convenient for spot selection that reaches the threshold pixel size.

[0031] This invention sequentially uses circular, cross-shaped, and star-shaped structural element expansion to filter out salt-and-pepper noise and banded noise in a coarse-to-fine manner. The final step, rectangular structural element erosion, expands the compressed effective spot size after filtering out salt-and-pepper and banded noise, facilitating subsequent spot identification and extraction. This sequential processing effectively filters out salt-and-pepper and banded noise from overexposed laser spot images caused by grating diffraction while preserving effective spot information.

[0032] Meanwhile, the effective information in an overexposed diffraction spot image is the regularly arranged circular spot, while the invalid information is band noise and salt-and-pepper noise. Band noise appears as irregular bands, while salt-and-pepper noise appears as dense dots. This arrangement of structural elements effectively filters out salt-and-pepper noise and band noise while preserving the effective spot.

[0033] In summary, this invention provides a method for extracting laser spot images from overexposed grating diffraction, which solves the problem of distinguishing between laser and stray light mixed in the photodetector under excessively high laser energy. At the same time, it can filter out background noise and clearly distinguish useful spot information from other information in overexposed grating diffraction laser images.

[0034] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the appended claims.

Claims

1. An overexposed grating diffraction laser spot pattern image extraction method, characterized by, The method comprises the following steps: Step S1: obtaining an original grating diffraction overexposed laser spot image; Step S2: one-dimensional threshold segmentation processing is performed on the original grating diffraction overexposed laser spot image to obtain a segmentation threshold ; Step S3: based on the segmentation threshold The overexposed laser spot image is binarized. Step S4: performing first expansion processing on the binary processed image by using a circular structural element, wherein the first expansion processing is used for strengthening the circular spot and filtering out the salt and pepper noise in the image; Step S5: performing second expansion processing on the first expansion processed image by using a cross-shaped structural element, wherein the second expansion processing is used for strengthening the circular spot and filtering out the non-horizontal and non-vertical direction strip noise; Step S6: performing third expansion processing on the second expansion processed image by using a rice-shaped structural element, wherein the second expansion processing is used for strengthening the circular spot and filtering out the horizontal and vertical direction strip noise; Step S7: performing corrosion processing on the third expansion processed image by using a rectangular structural element to obtain a final processed image, wherein the corrosion processing is used for uniformly expanding the circular spot.

2. The method of claim 1, wherein the overexposed grating diffraction laser spot pattern image is extracted by using a method comprising: The pixel value of each pixel point on the one-dimensional threshold segmentation processed image is: wherein, represents a pixel value of the one-dimensional threshold segmentation-processed image at a position , represents a threshold parameter obtained by the one-dimensional threshold segmentation.

3. The method of claim 1, wherein the overexposed grating diffraction laser spot pattern image is extracted by: The circular structural element R1 is as follows: 。 4. The method of claim 1, wherein the overexposed grating diffraction laser spot pattern image is extracted by using a method comprising: The cross-shaped structural element R2 is as follows: 。 5. The method of claim 1, wherein the overexposed grating diffraction laser spot pattern image is extracted by using a method comprising: The rice-shaped structural element R3 is as follows: 。 6. The method of claim 1, wherein the overexposed grating diffraction laser spot pattern image is extracted by using a method comprising: The rectangular structural element R4 is as follows: 。

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