A turbulence noise suppression device and method based on frosted glass filtering in an imaging system

Abstract

This invention discloses a turbulence noise suppression device and method based on frosted glass filtering in an imaging system. The device inserts a frosted glass lens between two lenses in an optical imaging system, allowing the light signal to pass through turbulence and the optical imaging system, resulting in a clear image on the image acquisition system and determining the position of the frosted glass lens. This clear image means that every detail of the image sensor can be recognized by the image acquisition system. The device also includes an image enhancement unit, which uses image enhancement technology to enhance the image acquired by the image acquisition system, obtaining an image after turbulence noise suppression. This invention effectively suppresses turbulence noise by combining frosted glass filtering and image enhancement technology.

Description

Technical Field

[0001] This invention relates to a turbulence noise suppression device and method based on frosted glass filtering in an imaging system, belonging to the field of noise suppression technology. Background Technology

[0002] Turbulent noise is the noise radiated by Reynolds stress in a flow. Turbulence is a very common type of flow, originating from flow instability. The stability of a flow is related to the Reynolds number; when the Reynolds number exceeds a certain critical value, a small disturbance in the fluid will continue to grow and eventually develop into turbulence.

[0003] Optical imaging systems utilize the principle that when light waves are shone onto a target, a portion of the reflected light beam is detected by a detection system to obtain target information and reconstruct an image of the target. Since optical imaging systems operate in an atmospheric environment, they inevitably encounter atmospheric turbulence. Atmospheric turbulence distorts the phase of light waves, reducing the resolution of the optical imaging system and affecting image quality.

[0004] In addition, underwater imaging is also a hot research topic. Due to its advantages of simple system structure, high imaging resolution, and intuitive target detection, it has been widely used in marine resource exploration, biological research, seabed archaeology, and marine search and rescue. However, underwater imaging is also affected by turbulence noise. Unlike atmospheric turbulence, the refractive index fluctuations in ocean turbulence are caused by changes in temperature and salinity, and its refractive index fluctuation spatial power spectrum has a complex double-peak structure. Obviously, underwater turbulence in the natural environment is an important factor limiting the quality of optical imaging. Based on the above background discussion, the following conclusions can be drawn: (1) Turbulence noise is ubiquitous in the natural environment and cannot be prevented by certain means; (2) Both atmospheric turbulence and underwater turbulence will have a great impact on the imaging of optical imaging systems, thus limiting the quality of optical imaging. Summary of the Invention

[0005] The purpose of this invention is to provide a turbulence noise suppression device and method based on frosted glass filtering in an imaging system. By inserting frosted glass into the imaging system, the imaging system can still form an image after passing through turbulence. By effectively combining it with commonly used image processing algorithms, the effect of suppressing turbulence noise can be better achieved.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] This invention provides a turbulence noise suppression device based on frosted glass filtering in an imaging system, used in an optical imaging system where turbulence exists between the optical imaging system and the target under test. The device includes a frosted glass plate inserted between two lenses of the optical imaging system. The position of the frosted glass plate is determined by placing a calibration plate at the target under test, so that the light signal from the calibration plate, after passing through the turbulence and the optical imaging system with the frosted glass plate inserted, can be clearly imaged on the image acquisition system, thus determining the position of the frosted glass plate. Clear imaging means that every detail of the calibration plate can be recognized by the image acquisition system.

[0008] The device also includes an image enhancement device.

[0009] The image enhancement device is used to perform image enhancement processing on the image obtained by the image acquisition system to obtain an image after suppressing turbulence noise.

[0010] Furthermore, the frosted glass has a mesh count greater than 600.

[0011] Furthermore, the frosted glass has a mesh count of 1500.

[0012] Furthermore, the optical imaging system is a 4f system.

[0013] Furthermore, the calibration board is selected as the USAF1951 board.

[0014] Furthermore, the image acquisition system is a CCD.

[0015] Furthermore, the turbulence is atmospheric or underwater turbulence.

[0016] Furthermore, the image enhancement device is specifically used for,

[0017] The image obtained by the image acquisition system can be enhanced using any of the following methods:

[0018] Sharpening filtering methods, edge detection methods, and methods that first perform mean filtering and then edge detection.

[0019] This invention also provides a method for suppressing turbulence noise in an imaging system based on frosted glass filtering, comprising:

[0020] Insert the frosted glass between the two lenses of the optical imaging system;

[0021] The calibration plate is placed at the location of the target to be measured, and there is turbulence between the optical imaging system and the target to be measured;

[0022] The frosted glass is moved back and forth so that the light signal from the calibration plate can be clearly imaged on the image acquisition system after passing through the turbulence and optical imaging system, thus determining the position of the frosted glass; the clear imaging means that every detail of the calibration plate can be recognized by the image acquisition system;

[0023] Remove the calibration plate and acquire an image of the target under test using an image acquisition device;

[0024] The acquired image of the target under test is subjected to image enhancement processing to obtain an image after suppressing turbulence noise.

[0025] The beneficial effects of this invention are as follows:

[0026] This invention provides a turbulence noise suppression device based on frosted glass filtering in an imaging system. By inserting frosted glass into the imaging system, the system can still form an image after passing through turbulence. By effectively combining it with commonly used image processing algorithms, the device can better suppress turbulence noise. Attached Figure Description

[0027] Figure 1 This is an example of the application of the turbulence noise suppression device based on frosted glass filtering in the imaging system provided by the present invention during the imaging process;

[0028] Figure 2 This invention illustrates the imaging results when the frosted glass is inserted into the optical imaging system at different positions.

[0029] Figure 3 In one embodiment of the present invention, the pattern of the number "4" is placed in the imaging system as the target to be imaged, and the images are obtained before and after the frosted glass is inserted. Figure 3 (a) is the image obtained without inserting frosted glass. Figure 3 (b) is the image obtained by inserting frosted glass;

[0030] Figure 4 To Figure 3 The result after sharpening and filtering the two images; Figure 4 (a) is for Figure 3 (a) The result after sharpening filtering. Figure 4 (b) for Figure 3 (b) The result after sharpening filtering;

[0031] Figure 5 To Figure 3 The result after edge detection of the two images; Figure 5 (a) is for Figure 3 (a) The result after edge detection. Figure 5 (b) for Figure 3 (b) The result after edge detection;

[0032] Figure 6 To Figure 3 The result of mean filtering and then edge detection on the two images; Figure 6 (a) is for Figure 3 (a) The result of edge detection after mean filtering. Figure 6 (b) for Figure 3 (b) The result of edge detection after mean filtering. Detailed Implementation

[0033] The present invention will now be further described. The following embodiments are only used to more clearly illustrate the technical solution of the present invention, and should not be used to limit the scope of protection of the present invention.

[0034] Normally, objects passing through turbulent flow generate noise, and frosted glass also scatters images, degrading image quality. This invention discovers that when frosted glass is combined with a lens, a clear image can be formed when the frosted glass is in a certain position. Based on this, combined with image enhancement technology, turbulent noise can be suppressed.

[0035] Based on the above-described inventive concept, this invention provides a turbulence noise suppression device based on frosted glass filtering in an imaging system. This device is used in an optical imaging system where turbulence exists between the optical imaging system and the target under test. The device includes a frosted glass plate inserted between two lenses of the optical imaging system. The position of the frosted glass plate is defined such that when a calibration plate is placed at the target under test, the light signal from the calibration plate, after passing through the turbulence and the optical imaging system with the frosted glass plate inserted, can be clearly imaged on the image acquisition system. It should be noted that clear imaging means that every detail of the calibration plate can be recognized by the image acquisition system.

[0036] The turbulence noise suppression device also includes an image enhancement device.

[0037] The image enhancement device is used to enhance the images obtained by the image acquisition system to obtain images after suppressing turbulence noise.

[0038] See Figure 1 This is an example of the application of the turbulence noise suppression device based on frosted glass filtering in the imaging system provided by the present invention during the imaging process, including the target to be measured, turbulence, the turbulence noise suppression device of the present invention, and the image acquisition system.

[0039] It should be noted that the frosted glass selected in this invention is required to have a mesh count greater than 600.

[0040] It should be noted that turbulence is caused by the environment, and can be atmospheric or underwater turbulence.

[0041] In one embodiment of the present invention, 1500-mesh frosted glass is selected.

[0042] In one embodiment of the present invention, the optical imaging system is a 4f system.

[0043] In one embodiment of the present invention, the image acquisition system employs a CCD.

[0044] It should be noted that the entire imaging system can only form an image when the frosted glass is in a specific position. Therefore, after setting up the optical path, the position of the frosted glass is determined by moving it back and forth. For example... Figure 2 As shown, a USAF1951 plate was selected as a calibration plate. The light signal emitted by this plate passed through turbulent water and entered an optical imaging system containing a frosted glass screen. By moving the frosted glass screen back and forth, the position of the screen where a clear image could be detected was determined. Figure 2 As can be seen, when the frosted glass is in a certain position, all the details in the USAF1951 board can be clearly distinguished, such as... Figure 2 As shown in the left-middle image, moving the frosted glass back and forth, even by only a millimeter, results in a completely blurred image received by the CCD, as... Figure 2 Images of other locations within the image.

[0045] Those skilled in the art should know that turbulence may have caused irreversible damage, and the resulting image cannot be recovered. However, the turbulence noise suppression device of the present invention can recover the resulting image after inserting frosted glass.

[0046] In this invention, frosted glass filtering combined with commonly used image enhancement techniques can suppress turbulence noise. It should be noted that this invention can be achieved using common image enhancement techniques. As for the specific image enhancement techniques used and the implementation details of these image enhancement techniques, these are all within the scope of existing technology.

[0047] It should be noted that after determining the position of the frosted glass using the calibration plate, the calibration plate is removed, and the image of the target to be tested is acquired using the image acquisition device.

[0048] It should be further noted that if the target under test is far from the imaging system, it is not practical to place the calibration plate at the distant target. In this case, the position of the frosted glass can be calibrated using the real-time image of the target under test. The frosted glass can be set to an adjustable position between the two lenses in the imaging system. The best imaging effect can be obtained by adjusting the position of the frosted glass back and forth.

[0049] In one embodiment of the present invention, the pattern of the number "4" is used as the image to be generated. Figure 3 (a) is an image collected by the optical imaging system after passing through turbulence without the frosted glass inserted. Figure 3(b) is an image collected by an optical imaging system after the frosted glass is inserted at a specific location and passes through turbulence.

[0050] It can be seen that, Figure 3 The pattern of the number "4" in (a) became somewhat blurred after passing through turbulence, and produced a lot of noise with clear lines. Figure 3 (b) Although the image is also blurry, no major noise defects were found. The image consists of a series of noise points, which makes it more suitable for image enhancement techniques to restore.

[0051] In one embodiment of the present invention, a sharpening filter is used to... Figure 3 (a) and Figure 3 The image in (b) is processed to obtain Figure 4 As can be seen, after sharpening the two images, the image before inserting the frosted glass becomes completely black, as shown below. Figure 4 (a), and the image after inserting the frosted glass still clearly shows the number "4", such as Figure 4 (b). It can be seen that the image after frosted glass insertion can be effectively combined with sharpening filtering to achieve noise reduction.

[0052] In one embodiment of the present invention, edge detection is used to... Figure 3 (a) and Figure 3 The image in (b) is processed to obtain Figure 5 As can be seen, after edge detection, only a faint trace remains in the image before the frosted glass is inserted, such as... Figure 5 (a), and the image after inserting the frosted glass still clearly shows the number "4", such as Figure 5 (b). It can be seen that the noise reduction effect is good after inserting frosted glass.

[0053] In one embodiment of the present invention, a mean filtering + edge detection method is used to... Figure 3 (a) and Figure 3 The image in (b) is processed to obtain Figure 6 .

[0054] contrast Figure 5 and Figure 6 It can be seen that after mean filtering and edge detection, the image before inserting the frosted glass is slightly better than the image without mean filtering, such as... Figure 6 (a), but compared to the image after frosted glass insertion, which is first mean filtered and then edge detected, such as Figure 6 (b) There is still a significant gap.

[0055] By comparing the images before and after insertion using multiple image processing algorithms, it is clear that the image after frosted glass insertion not only achieves noise reduction through physical means and saves computing resources, but also its effect when combined with image processing algorithms is far superior to the image before insertion.

[0056] Based on the above-mentioned turbulence noise suppression device, the present invention provides a turbulence noise suppression method based on frosted glass filtering in an imaging system, comprising:

[0057] Insert the frosted glass between the two lenses of the optical imaging system;

[0058] The calibration plate is placed at the location of the target to be measured, and there is turbulence between the optical imaging system and the target to be measured;

[0059] The frosted glass is moved back and forth so that the light signal from the calibration plate can be clearly imaged on the image acquisition system after passing through the turbulence and optical imaging system, thus determining the position of the frosted glass; the clear imaging means that every detail of the calibration plate can be recognized by the image acquisition system;

[0060] Remove the calibration plate and acquire an image of the target under test using an image acquisition device;

[0061] The acquired image of the target under test is subjected to image enhancement processing to obtain an image after suppressing turbulence noise.

[0062] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A device for turbulence noise suppression based on ground glass filtering in an imaging system, used in an optical imaging system, wherein there is turbulence between the optical imaging system and a target to be measured; characterized in that, The device comprises a ground glass which is inserted between two lenses of the optical imaging system; the ground glass is positioned in such a way that a calibration board is placed at the target to be measured, and the light signal of the calibration board can be clearly imaged on an image acquisition system after passing through the turbulence and the optical imaging system with the ground glass inserted, so as to determine the position of the ground glass; the clear imaging means that each detail of the calibration board can be recognized by the image acquisition system; The device further comprises an image enhancement device, The image enhancement device is used for image enhancement processing of the image obtained by the image acquisition system, so as to obtain an image after turbulence noise is suppressed.

2. The device for turbulence noise suppression based on ground glass filtering in an imaging system according to claim 1, characterized in that, The ground glass has a mesh number greater than 600 meshes.

3. The device for turbulence noise suppression based on ground glass filtering in an imaging system according to claim 2, characterized in that, The ground glass has a mesh number of 1500 meshes.

4. The device for turbulence noise suppression based on ground glass filtering in an imaging system according to claim 1, characterized in that, The optical imaging system is a 4f system.

5. The device for turbulence noise suppression based on ground glass filtering in an imaging system according to claim 1, characterized in that, The calibration board is selected from a USAF1951 board.

6. The device for turbulence noise suppression based on ground glass filtering in an imaging system according to claim 1, characterized in that, The image acquisition system is a CCD.

7. The device of claim 1, wherein the device is implemented in an imaging system. The turbulence is atmospheric turbulence or underwater turbulence.

8. The device of claim 1, wherein the device is implemented in an imaging system. The image enhancement device is specifically used for, The image obtained by the image acquisition system is processed by any one of the following image enhancement methods: a sharpening filter method, an edge detection method, and a method of first performing mean filter and then performing edge detection.

9. A method for turbulent noise suppression based on ground glass filtering in an imaging system, characterized in that, The method comprises the following steps: inserting a ground glass between two lenses of an optical imaging system; placing a calibration board at a target to be measured, and there is turbulence between the optical imaging system and the target to be measured; moving the ground glass forward and backward, so that the light signal of the calibration board can be clearly imaged on an image acquisition system after passing through the turbulence and the optical imaging system, and the position of the ground glass is determined; the clear imaging means that each detail of the calibration board can be recognized by the image acquisition system; removing the calibration board, and obtaining an image of the target to be measured by the image acquisition system; performing image enhancement processing on the obtained image of the target to be measured, so as to obtain an image after turbulence noise is suppressed.

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