Pressure-sensitive paint image light attenuation compensation method, device, equipment and medium

Abstract

The application provides a pressure-sensitive paint image light attenuation compensation method, device, equipment and medium, and relates to the technical field of image processing. The method compensates the light attenuation of the mean image corresponding to the image of the measured object based on the attenuation rate of the pressure-sensitive paint under the action of the light source, can compensate the normal attenuation of the pressure-sensitive paint to the mean image, improves the accuracy of the mean image, and further improves the accuracy of the pressure field.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of image processing, in particular to a pressure-sensitive paint image light attenuation compensation method and device, equipment and medium. BACKGROUND

[0002] PSP technology (Pressure Sensitive Paint technique) is a non-contact full-field pressure measurement method based on image processing. The pressure-sensitive material is used as the coating on the model surface, and when a laser or ultraviolet LED is used as the excitation light source, the luminescent molecules and oxygen in the coating undergo oxygen quenching reaction. The change of the fluorescence intensity of the model surface coating is converted into a pseudo-color image by a CCD camera, and finally the surface pressure distribution is obtained through computer graphics processing.

[0003] In the PSP technology, coating light attenuation compensation is a necessary link to realize high-precision pressure field reconstruction, which is necessary due to the system performance energy loss in the process of light-induced luminescence signal along the light path. According to the Stern-Volmer relationship, the PSP luminescence intensity and oxygen partial pressure have a quantitative relationship, but this relationship only holds when the photons are completely received by the detector. However, in actual wind tunnel tests, the spatial irradiance attenuation caused by model curvature, uneven spraying thickness and light source angle difference, as well as the spectral attenuation caused by lens vignetting and the wavelength-dependent transmittance of the filter, will significantly reduce the local signal-to-noise ratio. When precise measurement of small range pressure changes is performed, the light attenuation effect will cause obvious deviation in the measurement results. Li et al. conducted light attenuation analysis of domestic PSP in PSP calibration measurement, and obtained a light attenuation rate of 4% / h. In the case of small pressure fluctuations, the light attenuation effect may mask or exacerbate these changes, making the pressure measurement results no longer accurate. In addition, the calibration experiments reported in the literature show that the PSP image without light attenuation compensation can produce large pressure deviations in areas with large curvature. The existing PSP light attenuation compensation methods mainly rely on the "reference image ratio" and "empirical mapping matrix" two technical routes, but both have obvious limitations in engineering applications:

[0004] 1. The reference image ratio method requires the acquisition of an additional "uniform illumination reference image" under windless conditions to eliminate errors caused by spatial inhomogeneity of the light source, coating thickness, and differences in probe concentration. However, when the model experiences millimeter-level vibrations or thermal deformation during operation, the surface normal and illumination / observation geometry change in real time, causing the pixels between the reference image and the running image to no longer correspond one-to-one. Forcing a ratio will amplify the error. Sakaue et al.'s two-component PSP attempted to solve this problem with an "oxygen-insensitive" reference probe, but the overlap of the emission spectra of the active probe and the reference probe caused fluorescence resonance energy transfer (FRET), which reduced the pressure sensitivity. Furthermore, the channel crosstalk of the color high-speed camera further compressed the dynamic range.

[0005] 2. The empirical mapping matrix method typically establishes a "light intensity-grayscale" mapping table before the experiment using grayscale targets or Lambertian whiteboards, assuming that this mapping remains constant throughout the entire field and at all times. In actual wind tunnels, the aging and temperature rise of the light source, the change in the refractive index of the window glass with temperature, and the elastic deformation of the model all alter the local incident angle and observation angle, causing nonlinear drift in the mapping relationship. Furthermore, once the mapping matrix is ​​calibrated, it cannot be updated online, making it unsuitable for long-term continuous experiments or dynamic scanning with varying angles of attack. Both the ratio method and the matrix method treat light attenuation as a static error related only to spatial position, ignoring the dynamic characteristics of the PSP's own luminous intensity changing with temperature and pressure coupling. Under thin coating conditions (<5μm), the signal-to-noise ratio is already limited, and the light compensation process further amplifies photon statistical noise, making it difficult to eliminate the measurement error of high-frequency pressure pulsations through subsequent compensation. Summary of the Invention

[0006] This application provides a method, apparatus, device, and medium for compensating for light attenuation in pressure-sensitive paint images. Based on the attenuation rate of the pressure-sensitive paint itself under the action of a light source, it can compensate for the light attenuation of the mean image corresponding to the image of the object under test. It can compensate for the normal attenuation of the pressure-sensitive paint into the mean image, improve the accuracy of the mean image, and further improve the accuracy of the pressure field.

[0007] This application provides a method for compensating for light attenuation in pressure-sensitive paint images, comprising:

[0008] Acquire dark field images of the test object and multiple test images of the test object corresponding to multiple consecutive time points under the current pressure; the test images of the test object are images obtained by placing the test object under pressure, and the surface of the test object is coated with pressure-sensitive paint.

[0009] Determine the mean image based on multiple test images of the test analytes;

[0010] The light compensation image is determined based on the mean image, attenuation percentage, and dark field image of the test object; the attenuation percentage characterizes the attenuation rate of the pressure-sensitive paint under the action of a light source.

[0011] Based on the light compensation image, equation inversion is performed to obtain the pressure field of the test sample.

[0012] Optionally, the light compensation image is determined based on the mean image, the attenuation percentage, and the dark field image of the object to be measured, and the method comprises:

[0013] The light compensation image is determined based on the mean image, the dark field image, and a light compensation formula, and the light compensation formula comprises:

[0014] ;

[0015] wherein, is the light compensation image, is the mean image, is the attenuation percentage, is the dark field image.

[0016] Optionally, the method further comprises:

[0017] acquiring a plurality of first pressure reference images and a plurality of second pressure reference images;

[0018] determining a first image based on the plurality of first pressure reference images;

[0019] determining a second image based on the plurality of second pressure reference images;

[0020] determining the attenuation percentage based on the first image and the second image.

[0021] Optionally, after the attenuation percentage is determined based on the first image and the second image, the method further comprises:

[0022] acquiring a second pressure test image;

[0023] determining a second pressure compensation image based on the attenuation percentage, the second pressure test image, and the dark field image;

[0024] performing equation inversion based on the second pressure compensation image to obtain the sample pressure;

[0025] calibrating the attenuation percentage based on the sample pressure and a sensor pressure collected by a pressure sensor.

[0026] Optionally, the calibration of the attenuation percentage based on the sample pressure and the sensor pressure collected by the pressure sensor comprises:

[0027] if a difference between the sample pressure and the sensor pressure is greater than a preset difference, reacquiring the first pressure test image, the plurality of first pressure reference images, the plurality of second pressure test images, and the plurality of second pressure reference images, and determining an updated attenuation percentage.

[0028] Optionally, determining the attenuation percentage based on the first image and the second image comprises:

[0029] ;

[0030] wherein, the attenuation percentage, the first image, the second image.

[0031] To achieve the above object and other related objects, the present application provides a pressure-sensitive paint image light attenuation compensation device, comprising:

[0032] a data acquisition module configured to acquire a dark field image of a test object and a plurality of test images of the test object corresponding to a plurality of time points under a current pressure; the test images of the test object are images obtained when the test object is placed in a pressure environment, and the surface of the test object is coated with pressure-sensitive paint;

[0033] a first image determination module configured to determine a mean image based on the plurality of test images of the test object;

[0034] a second image determination module configured to determine a light compensation image based on the mean image, an attenuation percentage, and the dark field image of the test object; the attenuation percentage represents an attenuation rate of the pressure-sensitive paint under the action of a light source;

[0035] a pressure determination module configured to perform equation inversion based on the light compensation image to obtain a pressure field of the test sample.

[0036] Optionally, the second image determination module is further configured to:

[0037] determine the light compensation image based on the mean image, the dark field image, and a light compensation formula; the light compensation formula comprises:

[0038] ;

[0039] wherein, the light compensation image, the mean image, the attenuation percentage, the dark field image.

[0040] To achieve the above object and other related objects, the present application further provides an electronic device, comprising:

[0041] one or more processors;

[0042] a memory for storing program codes executable by the processor;

[0043] wherein, the processor is configured to execute the program codes to implement the pressure-sensitive paint image light attenuation compensation method described above.

[0044] To achieve the above object and other related objects, the present application also provides a computer readable storage medium, which stores a computer program, and the computer program, when executed by a processor of a computer, causes the computer to execute one or more of the above-mentioned pressure-sensitive paint image light attenuation compensation methods.

[0045] As described above, the pressure-sensitive paint image light attenuation compensation method, device, equipment and medium provided by the present application have the following beneficial effects:

[0046] The pressure-sensitive paint image light attenuation compensation method provided by the present application can compensate the mean image corresponding to the image of the measured object based on the decay rate of the pressure-sensitive paint itself under the action of the light source, can compensate the normal decay of the pressure-sensitive paint into the mean image, improve the accuracy of the mean image, and further improve the accuracy of the pressure field.

[0047] It should be understood that the foregoing general description and the following detailed description are only exemplary and explanatory, and cannot limit the present application. BRIEF DESCRIPTION OF DRAWINGS

[0048] The accompanying drawings, which are incorporated into and form part of the specification, illustrate embodiments consistent with the present application and, together with the description, serve to explain the principles of the application. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained from these drawings without creative labor for those skilled in the art. In the drawings:

[0049] Figure 1 is a flow chart of the pressure-sensitive paint image light attenuation compensation method according to an exemplary embodiment of the present application;

[0050] Figure 2 is a flow chart of the pressure-sensitive paint image light attenuation compensation method according to another exemplary embodiment of the present application;

[0051] Figure 3 is a schematic diagram of a test environment according to an exemplary embodiment of the present application;

[0052] Figure 4 is a comparison of the PSP image gray value and the pressure fitting curve before light attenuation compensation;

[0053] Figure 5 is a comparison of the PSP image gray value and the pressure fitting curve after light attenuation compensation;

[0054] Figure 6 is a block diagram of the pressure-sensitive paint image light attenuation compensation device according to an exemplary embodiment of the present application. DETAILED DESCRIPTION

[0055] The present application is illustrated by way of example and not limitation in the figures of the accompanying drawings and in the following detailed description with reference to the figures. Other advantages and beneficial implementations of the present application can become apparent to those of ordinary skill in the art, to which the present application pertains, upon reading the foregoing description with reference to the accompanying drawings and detailed description. The present application can be implemented in its various aspects by a wide variety of different embodiments, and its details can be varied without departing from the scope of the present application. It will be appreciated that the preferred embodiments are only for illustration and are not for the purpose of limiting the scope of the present application.

[0056] It is to be understood that the above-mentioned arrangements are merely illustrative for the basic concept of the present application, and thus the drawings only show the components related to the present application, rather than the components number, shape and size as implemented in practice. The actual implementation of the components may, therefore, be a matter of choice, and the layout of the components may, therefore, be more complex, and the shape, number and proportion of the components may, therefore, be changed arbitrarily.

[0057] In the following description, numerous specific details are discussed in order to provide a thorough understanding of the embodiments of the present application. However, it will be apparent to one of ordinary skill in the art that the embodiments of the present application can be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to avoid obscuring the embodiments of the present application.

[0058] Reference is made to Figure 1 , Figure 1 is a flow chart of a pressure-sensitive paint image light decay compensation method according to an exemplary embodiment of the present application. Reference is made to Figure 1 It can be seen that the pressure-sensitive paint image light decay compensation method can include:

[0059] In step S110, a dark-field image of the object to be measured and a plurality of test images of the object to be measured corresponding to a plurality of time points under a current pressure are obtained.

[0060] The test images of the object to be measured are images obtained by placing the object to be measured in a pressure environment, and the surface of the object to be measured is coated with pressure-sensitive paint.

[0061] In an embodiment of the present application, a dark-field image of the object to be measured and a plurality of test images of the object to be measured corresponding to a plurality of time points under a current pressure can be obtained. The experimental environment can be kept free of any light source exciting the pressure-sensitive paint, and the dark-field image of the object to be measured can be obtained by a CCD camera shooting the object to be measured. The plurality of test images of the object to be measured are images of the object to be measured shot by the CCD camera at the same position and angle, the object to be measured at the same position and angle, and the object to be measured under a pressure by the CCD camera at a plurality of time points in succession, for example, 10 images of the object to be measured can be continuously collected at a preset time interval, and the preset time interval can be set by a user according to actual conditions.

[0062] It should be noted that after the first image of the to-be-tested object placed in the dark field is obtained, the first image can be processed to obtain a first gray-scale image, and the first gray-scale image is determined as the dark field image of the to-be-tested object. After the LED light source or the laser is turned on to irradiate the to-be-tested object, a second image can be obtained, and after the second image is processed, a second gray-scale image is obtained, and the second gray-scale image is determined as the test image of the to-be-tested object.

[0063] In step S120, a mean image is determined based on a plurality of test images of to-be-tested objects.

[0064] In an embodiment of the present application, the mean image can be determined based on a plurality of test images of to-be-tested objects. Since the number of pixel points of each test image of the to-be-tested object is consistent, and the physical positions of each pixel point are consistent, that is, the position of any point in each test image of the to-be-tested object is consistent.

[0065] The collected images can be processed by averaging the pixel points, that is, for each pixel point of each test image of the to-be-tested object, the mean value of the pixel points at the same position in all test images of the to-be-tested object can be determined as the gray-scale value of the position, and the gray-scale mean values of the pixel points corresponding to all positions are combined to obtain the mean image.

[0066] In step S130, a light compensation image is determined based on the mean image, the decay percentage, and the dark field image of the to-be-tested object.

[0067] The decay percentage represents the decay rate of the pressure-sensitive paint under the action of the light source.

[0068] In an embodiment of the present application, the light compensation image can be determined based on the mean image, the decay percentage, and the dark field image of the to-be-tested object. The background noise of the camera corresponding to the dark field image of the to-be-tested object can be increased in the mean image to obtain a signal generated purely by the irradiation of the light source, improve the signal-to-noise ratio and the accuracy of the light compensation image, and further improve the accuracy of the pressure field of the test sample obtained in the subsequent step.

[0069] The working principle of the pressure-sensitive paint is based on the oxygen quenching effect: after the luminescent molecules in the paint layer are excited by a specific wavelength of light source, they will emit fluorescence, and the intensity of the fluorescence is inversely proportional to the oxygen partial pressure of the environment, that is, the pressure. By using a camera to collect the image of the luminescent intensity, the pressure image can be converted. However, under the continuous irradiation of the excitation light, the luminescent dye molecules will gradually decompose or deactivate due to photochemical reaction. Before the experiment starts, in a known and constant normal temperature and pressure environment, the sample is first irradiated and two reference images, namely a first image and a second image, are collected at a preset interval; since the pressure does not change, any change in the gray-scale values of the two images is only due to the light-induced decay itself. Therefore, the decay percentage can represent the inherent decay rate of the paint layer itself at a preset time interval under the intensity of the excitation light.

[0070] Step S140, equation inversion is performed based on the light compensation image to obtain the pressure field of the test sample.

[0071] In an embodiment of the present application, equation inversion can be performed based on the light compensation image to obtain the pressure field of the test sample.

[0072] It should be noted that equation inversion can be performed by the Stern-Volmer equation, i.e., the Stern-Volmer formula, to obtain the pressure field of the test sample. The Stern-Volmer equation can be expressed as:

[0073] ;

[0074] wherein, is a reference image, is a light compensation image, is a sample sensitivity, is a pressure to be calculated, i.e., a pressure of an environment in which the object to be measured is located, is a reference pressure, is a basic coefficient.

[0075] It should be noted that, The reference image can be obtained by measuring an initial image under a known and uniform reference pressure, performing image processing on the initial image to obtain a gray-scale image, and determining the gray-scale image as the reference image. For example, the corresponding reference image can be measured under the pressure in the plenum of a wind tunnel. is a reference pressure, i.e., a pressure when the reference image is collected.

[0076] In an embodiment of the present application, the process of determining the light compensation image based on the mean image and the dark field image of the object to be measured in step S130 can include:

[0077] The light compensation image is determined based on the mean image, the dark field image, and a light compensation formula. The light compensation formula includes:

[0078] ;

[0079] wherein, is a light compensation image, is a mean image, is a decay percentage, is a dark field image.

[0080] The decay percentage can be obtained by user calibration. The decay percentage The light compensation coefficient can be characterized. The intensity of the excitation light source can be unstable due to problems such as thermal drift or power fluctuations caused by long-time work during work of the excitation light source, which can cause different light intensities on the surface of the object to be measured. In order to eliminate the influence of light source fluctuation, the mean value image is light compensated using the attenuation percentage to obtain a light compensation image, which can improve the accuracy and reliability of the pressure measurement data.

[0081] Referring to Figure 2 which is a flowchart of a pressure-sensitive paint image light attenuation compensation method according to another exemplary embodiment of the present application. The pressure-sensitive paint image light attenuation compensation method can further include:

[0082] In step S210, a plurality of first pressure reference images and a plurality of second pressure reference images are acquired.

[0083] In an embodiment of the present application, the first pressure reference image of the second test sample placed in the normal pressure environment acquired by the CCD camera can be acquired. After the first pressure reference image is acquired, the second pressure reference image of the second test sample placed in the normal pressure environment acquired by the CCD camera can be acquired at a preset time interval. It should be noted that the first pressure reference image and the second reference image are in the same environment pressure, and the only difference is that the acquisition time interval between the second pressure reference image and the first pressure reference image is long. The preset time can be set by the operator according to the actual situation.

[0084] In step S220, a first image is determined based on a plurality of first pressure reference images.

[0085] In an embodiment of the present application, the first image can be determined based on a plurality of first pressure reference images. The second test sample can be placed in a normal pressure environment outside the calibration cavity, and a plurality of first pressure reference images of the second test sample in the normal environment are acquired by the CCD camera arranged at a fixed position. The mean value of the gray scale images of the plurality of first pressure reference images is determined as the first image.

[0086] In step S230, a second image is determined based on a plurality of second pressure reference images.

[0087] In an embodiment of the present application, the second image can be determined based on a plurality of second pressure reference images. The second test sample can be placed in a normal pressure environment outside the calibration cavity, and a plurality of second pressure reference images of the second test sample in the normal environment are acquired by the CCD camera arranged at a fixed position at a preset time interval after the first pressure reference image is acquired. The mean value of the gray scale images of the plurality of second pressure reference images is determined as the second image.

[0088] It should be noted that the acquisition time of each second pressure reference image is after the acquisition time of each first pressure reference image.

[0089] For example, the time interval between the acquisition of the first pressure reference image and the second pressure reference image can be any value within [0, 10 min].

[0090] In step S240, the attenuation percentage is determined based on the first image and the second image.

[0091] In the first embodiment of the present application, the attenuation percentage can be determined based on the first image and the second image.

[0092] ;

[0093] wherein, is the attenuation percentage, is the first image, is the second image.

[0094] In step S250, the second pressure test image is acquired.

[0095] In an embodiment of the present application, the same first test sample can be placed in the calibration cavity, the pressure in the calibration cavity can be set to a preset value, and the second pressure test image of the first test sample in the calibration cavity can be acquired at the same time when the second pressure reference image is acquired. That is, the acquisition time of the second pressure test image is consistent with the acquisition time of the second pressure reference image, but the test sample corresponding to the second pressure test image and the second pressure reference image is under different pressures.

[0096] In step S260, the second pressure compensation image is determined based on the attenuation percentage, the second pressure test image and the dark field image.

[0097] In an embodiment of the present application, the second pressure compensation image can be determined based on the attenuation percentage, the second pressure test image and the dark field image.

[0098] For example, the second pressure compensation image can be determined by the following formula:

[0099] ;

[0100] wherein, is the second pressure test image, is the second pressure compensation image.

[0101] In step S270, the sample pressure is obtained by equation inversion based on the second pressure compensation image.

[0102] In an embodiment of the present application, after the second pressure compensation image is obtained, the sample pressure can be obtained by equation inversion based on the second pressure compensation image, the second pressure reference image and the reference pressure corresponding to the second pressure reference image. ​

[0103] Step S280, based on the sample pressure and the sensor pressure collected by the pressure sensor, calibrating the attenuation percentage.

[0104] In an embodiment of the present application, the attenuation percentage can be calibrated based on the sample pressure and the sensor pressure collected by the pressure sensor. It should be noted that the sensor pressure is the pressure value in the calibration cavity when the second pressure test image is acquired, that is, the pressure value when the second pressure reference image is acquired.

[0105] In a possible implementation, the process of calibrating the attenuation percentage based on the sample pressure and the sensor pressure collected by the pressure sensor in step S250 can include: if the difference between the sample pressure and the sensor pressure is greater than a preset difference, re-collecting the first pressure test image, the plurality of first pressure reference images, the plurality of second pressure test images and the plurality of second pressure reference images, and determining an updated attenuation percentage.

[0106] It should be noted that the preset difference can be 50 Pa. If the difference between the sample pressure and the sensor pressure is greater than the preset difference, the light source can be turned off to allow the light source to recover to room temperature and / or self-calibrate inside the light source, and then steps S210 to S250 are executed again to determine the attenuation percentage. If the difference between the sample pressure and the sensor pressure is less than or equal to the preset difference, the attenuation percentage can be applied to steps S110 to S140.

[0107] It should be noted that to avoid overcompensation, |C|<1% is forced to be zero, that is, when the absolute value of the calculated attenuation percentage C is less than 1% (i.e. the gray scale change is less than 1%), it is treated as "measurement noise" rather than "real attenuation", and C=0 is directly set, without any light compensation, to avoid "overcorrection" due to small disturbances. |C|>5% triggers system self-check, that is, if the absolute value of C exceeds 5%, it means that the gray scale change is too large, which has exceeded the normal experimental expectation, and it may be that the LED suddenly loses stability, the PSP peels off in a large area, or the equipment is abnormal, at which time the system starts the self-check program, and the subsequent compensation is suspended to prevent the error coefficient from continuing to be transmitted.

[0108] For example, please refer to Figure 3This is a schematic diagram illustrating a test environment in an exemplary embodiment of this application. A first test sample 310 can be placed inside a calibration chamber 320, the pressure inside of which can be changed, thus changing the pressure of the environment in which the first test sample 310 is located. A second test sample 330 can be placed in the external normal environmental pressure. Pressure-sensitive paint can be sprayed onto both the first and second test samples 310. A photomultiplier tube 340 can be placed parallel to the calibration chamber 320, and can detect the stability of the laser emitted by the light source. An excitation light source 350 can be positioned in front of the calibration chamber 320, and a CCD camera 360 can also be positioned in front of the calibration chamber 320.

[0109] Calibration tests were performed on the PSP samples using two stationary PSP samples from the same batch. The samples used pentafluorotetraphenylporphyrin platinum as the luminescent molecule, a polymer as the main binder, and dichloromethane as the main solvent. The sample placement was as follows. Figure 3 As shown. Temperature was controlled at room temperature, and pressure ranged from 50 kPa to 150 kPa in 25 kPa increments. A continuous and stable excitation light source, a high-precision regulated LED, was used to illuminate the PSP sample under different pressure conditions. This source was placed approximately 1 m vertically from the calibration box to ensure uniform and stable excitation light illumination of the sample surface. Simultaneously, a photomultiplier tube (PMT) was placed parallel to the calibration box to monitor the stability of the light source. During the experiment, both the PSP sample and the PMT were positioned at the center of the excitation light source to avoid the PMT capturing edge light sources, thus ensuring the accuracy of the measurement results. A CCD camera was used to acquire the luminous intensity. The camera was fixed at a suitable distance from the calibration box, at a 90° angle, and on its central axis to ensure image accuracy and consistency. A filter with a center wavelength of 650 nm was fixed at the front lens of the CCD camera via a converter connector to filter non-featured fluorescence and improve image quality. Five grayscale images were captured in total. 100 kPa was used as the reference pressure, and the corresponding image grayscale value was the reference light intensity. Normalization is achieved by comparing the light intensity with that under reference pressure, and the sensitivity of the PSP sample is finally obtained according to the Stern-Volmer.

[0110] During the experiment, the pressure-sensitive paint images used had to be from the same batch of PSP samples. The images were cropped to generate uniformly sized pressure-sensitive paint images. The pressure was set from 96 kPa to 97 kPa in 50 Pa increments, and the light intensity values ​​of the samples were collected under different pressure conditions. Of the 21 data sets obtained, 13 were randomly selected for verification. 96.45 kPa was selected as the reference pressure. The corresponding measurement pressure was derived based on the sensitivity of the obtained PSP samples, and verification was performed using the pressure displayed on the sensor.

[0111] In the experiment, the PSP sample is tested in a calibration chamber, the pressure of the calibration chamber is controllable and can be displayed by a pressure sensor, and the accuracy of the PSP pressure measurement can be improved by noise reduction and light compensation. In actual wind tunnel applications, pressure measurement on the model surface requires pressure measurement holes to connect pressure scanning valves for pressure measurement. This pressure measurement method can only measure discrete points and the model punching cost is high, and punching cannot be performed in some special positions. The pressure-sensitive paint image light attenuation compensation method provided in the embodiments of the present application can measure the pressure of the model area without punching the model, has the characteristics of high resolution and low cost, improves the PSP measurement accuracy, and expands the application of PSP in actual wind tunnels.

[0112] For example, the images of the first test sample can be jointly denoised, and the gray value distribution of the PSP images is adjusted at any three positions in the first test sample, namely Position1, Position2 and Position3, so as to reduce the gray fluctuation between the original images. The high-frequency noise and unnecessary details in the image are effectively suppressed while the main structural information of the image is retained. In this way, the gray value fluctuation between different images is further reduced, and the overall consistency of the image is improved. Then, the light compensation method is performed, and after the compensation, the interference of the light attenuation effect on the experimental results is minimized, and the gray change in the image can more accurately map the pressure change. Figure 4 The comparison of the PSP image gray value and the pressure fitting curve before light attenuation compensation is shown. Figure 5 The comparison of the PSP image gray value and the pressure fitting curve after light attenuation compensation is shown. As can be seen from the figure, the consistency of the PSP measurement pressure data after compensation and the pressure data displayed by the sensor is significantly improved, and the measurement error of the PSP is effectively controlled within 50 Pa, indicating the effectiveness of the compensation measure. Figure 4 and Figure 5 In the above formulas, the abscissa represents the number of the first test sample, and the ordinate represents the pressure value determined based on the image of the first test sample.

[0113] To quantitatively verify the effectiveness of the pressure-sensitive paint image light attenuation compensation method provided in the embodiments of the present application in the PSP image recovery, the peak signal-to-noise ratio (PSNR) and the structural similarity (SSIM) are used as objective evaluation indexes. The experiment is completed under the static calibration condition of 97 kPa→96 kPa step 50 Pa. After estimating the attenuation percentage C and compensating pixel by pixel by the PSP image dynamic light compensation algorithm, the image noise is effectively suppressed, the gray consistency is significantly improved, and the objective indexes are improved to PSNR=46.02 dB and SSIM=0.99. The pressure-sensitive paint image light attenuation compensation method provided in the embodiments of the present application has high fidelity recovery capability for the texture and structure details of the PSP image while maintaining the micro-pressure measurement accuracy.

[0114] Figure 6 is a block diagram of a pressure sensitive paint image light attenuation compensation device shown in an example embodiment of the present application. As shown, the example pressure sensitive paint image light attenuation compensation device 600 includes: Figure 6

[0115] a data acquisition module 610 configured to acquire a dark field image of a test object and a plurality of test images of the test object corresponding to a plurality of time points under a current pressure, the test images of the test object being obtained when the test object is placed in a pressure environment, and a surface of the test object being coated with pressure sensitive paint;

[0116] a first image determination module 620 configured to determine a mean image based on the plurality of test images of the test object;

[0117] a second image determination module 630 configured to determine a light compensation image based on the mean image, an attenuation percentage, and the dark field image of the test object, the attenuation percentage representing an attenuation rate of the pressure sensitive paint under an action of a light source;

[0118] a pressure determination module 640 configured to perform equation inversion based on the light compensation image to obtain a pressure field of the test sample.

[0119] In an embodiment of the present application, the second image determination module is further configured to:

[0120] determine the light compensation image based on the mean image, the dark field image, and a light compensation formula, the light compensation formula including:

[0121] ;

[0122] wherein, is the light compensation image, is the mean image, is the attenuation percentage, is the dark field image.

[0123] In an embodiment of the present application, the pressure sensitive paint image light attenuation compensation device further includes:

[0124] a first image acquisition module configured to acquire a plurality of first pressure reference images and a plurality of second pressure reference images;

[0125] a first determination unit configured to determine a first image based on the plurality of first pressure reference images;

[0126] a second determination unit configured to determine a second image based on the plurality of second pressure reference images;

[0127] a data determination unit configured to determine the attenuation percentage based on the first image and the second image.

[0128] ​In an embodiment of the present application, the pressure-sensitive paint image light attenuation compensation device further comprises:

[0129] The second image acquisition module is configured to acquire a second pressure test image.

[0130] The compensation image determination module is configured to determine a second pressure compensation image based on the attenuation percentage, the second pressure test image, and the dark-field image.

[0131] The data processing module is configured to perform equation inversion based on the second pressure compensation image to obtain a sample pressure.

[0132] The data calibration module is configured to calibrate the attenuation percentage based on the sample pressure and a sensor pressure collected by the pressure sensor.

[0133] In an embodiment of the present application, the data calibration module is further configured to:

[0134] If the difference between the sample pressure and the sensor pressure is greater than a preset difference, the first pressure test image, the plurality of first pressure reference images, the plurality of second pressure test images, and the plurality of second pressure reference images are re-collected, and an updated attenuation percentage is determined.

[0135] In an embodiment of the present application, the data determination unit is further configured to:

[0136] ;

[0137] wherein, is the attenuation percentage, is the first image, is the second image.

[0138] It should be noted that the pressure-sensitive paint image light attenuation compensation device provided in the above embodiments and the pressure-sensitive paint image light attenuation compensation method provided in the above embodiments belong to the same concept, and the specific manner in which each module and unit performs operations has been described in detail in the method embodiments, which will not be repeated here. The pressure-sensitive paint image light attenuation compensation device provided in the above embodiments can allocate the above functions to different functional modules according to needs, i.e., divide the internal structure of the system into different functional modules to complete all or part of the functions described above, and this is not limited herein.

[0139] Embodiments of the present application also provide an electronic device, comprising: one or more processors; a storage device configured to store one or more programs, when the one or more programs are executed by the one or more processors, the electronic device implements the pressure-sensitive paint image light attenuation compensation method provided in each of the above embodiments.

[0140] Another aspect of the present application also provides a computer readable storage medium, which stores a computer program. The computer program is executed by a processor of a computer, so that the computer executes the pressure-sensitive paint image light attenuation compensation method provided in each of the above embodiments. The computer readable storage medium can be included in the electronic device described in the above embodiments, or can exist separately without being assembled into the electronic device.

[0141] Another aspect of the present application also provides a computer program product or a computer program, which includes computer instructions stored in a computer readable storage medium. A processor of a computer device reads the computer instructions from the computer readable storage medium, and the processor executes the computer instructions, so that the computer device executes the pressure-sensitive paint image light attenuation compensation method provided in each of the above embodiments.

[0142] In the embodiments of the present application, the terms "first" and "second" are only used for descriptive purposes, and should not be construed or implied as indicating or implying relative importance. Throughout the specification and claims, "comprise" and "include" are open-ended terms, and should be interpreted as "comprise but not limited to".

[0143] The above embodiments only exemplarily illustrate the principles and effects of the present application, and are not used to limit the present application. Any person skilled in the art can modify or change the above embodiments without departing from the spirit and scope of the present application. Therefore, all equivalent modifications or changes made by those skilled in the art without departing from the spirit and technical thought of the present application should be covered by the claims of the present application.

Claims

1. A method of compensating for light attenuation of a pressure sensitive paint image, characterized by, The method comprises the following steps: obtaining a dark field image of a test object and a plurality of test images of the test object corresponding to a plurality of time points under a current pressure; the test images of the test object are obtained under a pressure environment, and the surface of the test object is coated with pressure-sensitive paint; determining a mean image based on the plurality of test images of the test object; determining a light compensation image based on the mean image, a decay percentage and the dark field image of the test object; the decay percentage represents the decay rate of the pressure-sensitive paint under the action of a light source; performing equation inversion based on the light compensation image to obtain a pressure field of the test sample; determining the light compensation image based on the mean image, the dark field image and a light compensation formula, wherein the light compensation formula comprises: The method further comprises: ； wherein, is a light compensated image, is a mean image, is a percentage of attenuation, is a dark field image; obtaining a plurality of first pressure reference images and a plurality of second pressure reference images; determining a first image based on the plurality of first pressure reference images; determining a second image based on the plurality of second pressure reference images; determining a decay percentage based on the first image and the second image; determining the decay percentage based on the first image and the second image comprises: After determining the decay percentage based on the first image and the second image, the method further comprises: ； wherein, is the percentage of attenuation, is the first image, is the second image.

2. The method of claim 1, wherein the pressure sensitive paint image light attenuation compensation is performed by: obtaining a second pressure test image; determining a second pressure compensation image based on the decay percentage, the second pressure test image and the dark field image; performing equation inversion based on the second pressure compensation image to obtain a sample pressure; calibrating the decay percentage based on the sample pressure and a sensor pressure collected by a pressure sensor. Calibrating the decay percentage based on the sample pressure and the sensor pressure collected by the pressure sensor comprises:

3. The method of claim 2, wherein the pressure sensitive paint image light attenuation compensation is performed by: If the difference between the sample pressure and the sensor pressure is greater than a preset difference, re-collecting the first pressure test image, the plurality of first pressure reference images, the plurality of second pressure test images and the plurality of second pressure reference images, and determining an updated decay percentage. The method comprises the following steps:

4. A pressure sensitive paint image light attenuation compensation apparatus characterized by comprising: a data acquisition module for obtaining a dark field image of a test object and a plurality of test images of the test object corresponding to a plurality of time points under a current pressure; the test images of the test object are obtained under a pressure environment, and the surface of the test object is coated with pressure-sensitive paint; a first image determination module for determining a mean image based on the plurality of test images of the test object; a second image determination module for determining a light compensation image based on the mean image, a decay percentage and the dark field image of the test object; the decay percentage represents the decay rate of the pressure-sensitive paint under the action of a light source; a pressure determination module for performing equation inversion based on the light compensation image to obtain a pressure field of the test sample; the second image determination module is further used for: determining the light compensation image based on the mean image, the dark field image and a light compensation formula, wherein the light compensation formula comprises: The pressure-sensitive paint image light decay compensation device further comprises: ； wherein, is a light compensated image, is a mean image, is a percentage of attenuation, is a dark field image; a first image acquisition module for obtaining a plurality of first pressure reference images and a plurality of second pressure reference images; a first determination unit for determining a first image based on the plurality of first pressure reference images; a second determination unit for determining a second image based on the plurality of second pressure reference images; ​ a data determining unit configured to determine the percentage of attenuation based on the first image and the second image; the data determining unit is further configured to: ； wherein, is the percentage of attenuation, is the first image, is the second image.

5. An electronic device, comprising: The electronic device comprises: one or more processors; a memory for storing program codes executable by the processors; wherein the processors are configured to execute the program codes to implement the pressure-sensitive paint image light attenuation compensation method according to any one of claims 1 to 3.

6. A computer-readable storage medium, characterized in that, a computer program stored thereon, which, when executed by a processor of a computer, causes the computer to perform the pressure-sensitive paint image light attenuation compensation method according to any one of claims 1 to 3.

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