Camera exposure time control method and device under high dynamic background light intensity change

Abstract

The invention discloses a camera exposure time control method under high-dynamic background light intensity change, and aims to solve the problem of camera overexposure caused by environment light intensity change in optical measurement. The method comprises the following steps: building a test system, and setting a camera frame rate; setting initial exposure time, and shooting an image of the measured object to obtain an optimal gray scale; adjusting parameters of the signal processing circuit; and starting the to-be-tested equipment, and obtaining the exposure time when the ambient light intensity rapidly changes. According to the invention, an open-loop control method is applied, the ambient light intensity is captured in real time through the photodiode, and the ambient light intensity is converted into the camera exposure time inversely proportional to the ambient light intensity through the signal processing circuit, so that rapid adjustment of the camera exposure time is realized. Compared with a fixed exposure time measuring method and a traditional method based on an image gray value, the method has the advantages of being high in response speed, small in calculation burden, real-time in feedback and the like, and is particularly suitable for an application scene where the light intensity changes rapidly in a high-temperature environment.

Description

Technical Field

[0001] The present invention relates to the technical field of camera exposure control, and in particular to a method and device for controlling camera exposure time under high dynamic background light intensity changes. Background Art

[0002] Optical measurement technology plays a vital role in a variety of precision measurement scenarios, such as digital image correlation (DIC) technology, three-dimensional morphology measurement technology, material surface strain monitoring technology, etc. These technologies are widely used in aerospace, energy, manufacturing, transportation and other fields. However, in extreme environments such as rocket engine hot test, gas turbine testing, high enthalpy wind tunnel experiments and high-temperature material testing, due to strong radiation and rapid fluctuations in light intensity, the images captured by optical sensors are often overexposed, resulting in a significant decrease in measurement accuracy. This overexposure phenomenon is due to the saturation of the sensor under high light intensity, which cannot capture the real light signal changes, thus affecting subsequent image processing and analysis.

[0003] Existing technologies usually rely on manually adjusting the camera's exposure time or using fixed exposure parameters for measurement. However, in scenes where light intensity changes dramatically, fixed exposure time is difficult to cope with complex dynamic environments, resulting in unstable image quality. Traditional exposure control methods make adjustments based on image grayscale value feedback, but there is a certain response delay in image grayscale calculation, especially in high temperature or high-speed dynamic change environments. It is difficult to make adjustments in time, which easily leads to distortion of measurement data.

[0004] Therefore, there is an urgent need for a technical solution that can adaptively adjust the exposure time in real time, which is suitable for various optical sensor measurement scenarios and can ensure measurement accuracy and image quality under high dynamic light intensity changes. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a method and device for controlling the exposure time of a camera under high dynamic background light intensity changes in view of the deficiencies of the above-mentioned prior art.

[0006] In order to achieve the above technical objectives, the technical solution adopted by the present invention is:

[0007] A method for controlling camera exposure time under high dynamic background light intensity changes comprises the following steps:

[0008] Step S1, build a test system and set the camera frame rate f;

[0009] Step S2: Set the initial exposure time of the camera to Δt 0 , shoot the object under test without light intensity change, the image grayscale obtained at this time is the optimal grayscale g 0 , at this time the light intensity input to the camera is I 0 ;

[0010] Step S3: Adjust the signal processing circuit that controls the camera exposure time so that the input light intensity is I 0 When the signal processing circuit outputs the exposure time Δt 0 ;

[0011] Step S4: Start the device under test, the ambient light intensity I changes rapidly, the camera inputs the light intensity I, and the signal processing circuit outputs the exposure time Δt, so that the grayscale of the captured image is always kept at g 0 .

[0012] To optimize the above technical solutions, the specific measures taken also include:

[0013] A camera exposure time control device under high dynamic background light intensity change includes a signal processing circuit applied to the camera, the signal processing circuit includes a light intensity acquisition module, a division circuit module, an integration circuit module and a pulse signal control module connected in sequence;

[0014] The light intensity acquisition module is used to detect the changes in ambient light intensity in real time, and convert the light intensity signal into a voltage signal and send it to the division circuit module. The division circuit module is used to operate on the voltage signal. The voltage signal after operation is inversely proportional to the transformed ambient light intensity, and the voltage signal after operation is sent to the integration circuit module. The gain of the division circuit module can be adjusted according to the range of changes in ambient light intensity. The integration circuit module is used to convert the voltage signal after operation into a digital signal that can control the pulse width, and send the digital signal to the pulse signal control module. The pulse signal control module generates a pulse signal according to the digital signal. The rising edge and falling edge of the pulse signal correspond to the start and end of camera exposure respectively, thereby realizing real-time camera exposure time adjustment.

[0015] The light intensity collection module is a photodiode, the photodiode detection wavelength range is 400 to 1100 nanometers, and the photodiode is installed in front of the camera.

[0016] The pulse signal control module is a voltage-controlled oscillator, which can convert a voltage signal into a pulse width modulation signal.

[0017] The camera exposure time control device under high dynamic background light intensity changes also includes a computer and an image acquisition system. The computer is respectively connected to the image acquisition system and the pulse signal control module signal. The image acquisition system is used to acquire and process the image output by the camera and send the image to the computer. The pulse signal control module sends the pulse signal to the computer. The computer is used to process the image and monitor and adjust the exposure time according to the received pulse signal.

[0018] The computer's processor is a multi-core CPU or a device with GPU acceleration.

[0019] An exposure control method in three-dimensional DIC measurement, using the above-mentioned camera exposure time control device under high dynamic background light intensity change, includes the following steps: installing a light intensity acquisition module in front of a dual camera to detect the change of ambient light intensity in real time; converting the detected light intensity signal into a voltage signal; processing the voltage signal through an analog operational amplifier circuit; using a pulse signal control module to generate a pulse signal; and controlling the camera exposure time through the pulse signal.

[0020] The invention discloses an exposure control method for three-dimensional structured light topography measurement, which uses the above-mentioned camera exposure time control device under high dynamic background light intensity change, and comprises the following steps: a projection device projects specific structured light onto the object to be measured; a light intensity acquisition module is installed in front of two cameras to detect the change of ambient light intensity in real time; the detected light intensity signal is converted into a voltage signal; the voltage signal is processed by an analog operational amplifier circuit; a pulse signal control module is used to generate a pulse signal; the exposure time of the camera is controlled by the pulse signal; the two cameras synchronously acquire images; a computer and an image acquisition system acquire and process images to reconstruct the three-dimensional topography of the object.

[0021] The beneficial effect of the present invention is that by adjusting the camera exposure time in real time, the problem of image overexposure caused by rapid changes in background light intensity during optical measurement is solved. Its application scope includes but is not limited to optical measurement technologies that require background light illumination, such as digital image correlation (DIC) measurement and three-dimensional shape measurement, and is particularly suitable for scenes with high dynamic background light changes, such as rocket engine hot test and high enthalpy wind tunnel experiment.

[0022] In addition, the present invention also has the following advantages:

[0023] Fast response speed: The present invention detects the ambient light intensity in real time through a photodiode, and quickly generates a pulse signal proportional to the change in light intensity through a voltage-controlled circuit, avoiding the calculation delay problem in the traditional image grayscale value adjustment method, and is particularly suitable for scenes with rapid changes in light intensity.

[0024] Reduced computational burden: Compared with traditional exposure control methods, the present invention does not rely on image grayscale value calculations, but directly adjusts the exposure time based on the light intensity signal, which reduces the computational burden of the processor and simplifies the system design.

[0025] Real-time feedback: The photodiode can capture changes in ambient light intensity in real time and quickly feed it back to the exposure control circuit, enabling instant adjustment of the camera exposure time to ensure the accuracy of exposure control.

[0026] Strong adaptability: The present invention is particularly suitable for scenes with rapid light intensity changes in high-temperature environments, such as rocket engine hot testing, high-temperature casting, etc. By adaptively adjusting the exposure time, overexposure can be effectively reduced, and the image quality and measurement accuracy of digital image correlation measurements can be improved.

[0027] Flexible and scalable: The system design of the present invention can be flexibly expanded according to different application requirements, supports the combined use of multiple photodiodes, and can also be connected to a computer system to achieve remote control and monitoring, which is suitable for different industrial scenarios. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 The figure is a flow chart of the camera exposure time control method under high dynamic background light intensity change of the present invention.

[0029] Figure 2 Schematic diagram of signal transformation in the camera exposure time control method.

[0030] Figure 3 Schematic diagram of a camera exposure control device in a three-dimensional digital image correlation (3D-DIC) measurement system.

[0031] Figure 4 Schematic diagram of the camera exposure control device in the three-dimensional shape measurement system.

[0032] Figure 5 FIG. 2 is a device diagram of a signal processing circuit.

[0033] Figure numerals: 1. light source; 11. one of the dual light sources in 3D-DIC; 12. the second of the dual light sources in 3D-DIC; 2. the deformable part to be measured, whose surface is sprayed with irregular speckles; 3. camera; 31. one of the dual cameras in 3D-DIC; 32. the second of the dual cameras in 3D-DIC; 4. photodiode; 5. signal processing circuit; 51. division circuit module; 52. integration circuit module; 53. pulse signal control module; 6. computer and image acquisition system; 7. projection equipment; 8. object of morphology to be measured. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical solutions and advantages of the present application clearer, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not intended to limit the present application. Based on the embodiments provided in the present application, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present application.

[0035] Obviously, the drawings described below are only some examples or embodiments of the present application. For ordinary technicians in this field, the present application can also be applied to other similar scenarios based on these drawings without creative work. In addition, it can also be understood that although the efforts made in this development process may be complicated and lengthy, for ordinary technicians in this field related to the content disclosed in this application, some changes in design, manufacturing or production based on the technical content disclosed in this application are just conventional technical means, and should not be understood as insufficient content disclosed in this application.

[0036] Reference to "embodiments" in this application means that a particular feature, structure, or characteristic described in conjunction with the embodiments may be included in at least one embodiment of the present application. The appearance of the phrase in various locations in the specification does not necessarily refer to the same embodiment, nor is it an independent or alternative embodiment that is mutually exclusive with other embodiments. It is explicitly and implicitly understood by those of ordinary skill in the art that the embodiments described in this application may be combined with other embodiments without conflict.

[0037] Unless otherwise defined, the technical terms or scientific terms involved in this application should be understood by people with ordinary skills in the technical field to which this application belongs. The words "one", "a", "a", "the" and the like involved in this application do not indicate a quantitative limitation, and may represent the singular or plural. The terms "include", "comprise", "have" and any of their variations involved in this application are intended to cover non-exclusive inclusions; for example, a process, method, system, product or device that includes a series of steps or units (units) is not limited to the listed steps or units, but may also include steps or units that are not listed, or may also include other steps or units inherent to these processes, methods, products or devices. The words "connect", "connected", "coupled" and the like involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The "multiple" / "several" involved in this application refers to two or more. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships, for example, "A and / or B" can mean: A exists alone, A and B exist at the same time, and B exists alone. The character " / " generally indicates that the objects before and after are in an "or" relationship. The terms "first", "second", "third", etc. involved in this application are only used to distinguish similar objects and do not represent a specific ordering of the objects.

[0038] The present invention provides an adaptive camera exposure time control method and device, aiming to solve the problem of camera overexposure caused by rapid changes in ambient light intensity. The method uses a photodiode to detect light intensity signals, and adjusts the camera exposure time in real time through an analog operational amplifier circuit and a voltage control circuit to ensure measurement accuracy and image quality.

[0039] Embodiment 1: Detailed process of camera exposure time control method

[0040] During the camera's imaging process, the grayscale of the image captured by the camera mainly depends on: the ambient light intensity I entering the camera, the camera's light sensitivity coefficient α, the camera's exposure time Δt, and the camera grayscale g = α × I × Δt. To avoid overexposure of the camera, it is necessary to ensure that the grayscale of the captured image remains basically constant. Assume that the initial light intensity when the ambient light intensity does not fluctuate is I 0 , when the camera exposure time is set to Δt 0 When the optimal grayscale of the image is g 0 When the ambient light intensity I changes rapidly, the exposure time Δt to obtain the best grayscale is g 0 / αI=Δt 0 ×I 0 / I, the actual exposure time is inversely proportional to the ambient light intensity.

[0041] According to the above principles, an open-loop control method is designed to achieve adaptive control of the camera exposure time through the signal processing circuit. For the specific process, see Figure 1 The specific implementation steps are as follows:

[0042] Step S1, building a test system, includes: building a test system according to the test method and test conditions used, turning on a camera, and setting a camera frame rate f.

[0043] Step S2, obtaining the best grayscale, including: setting the initial exposure time of the camera to Δt without turning on the exposure time control system 0 , shooting without light intensity change (I=I 0 ) is the object being measured. The image grayscale obtained at this time is the optimal grayscale g 0 .

[0044] Step S3, adjusting the parameters of the signal processing circuit, including: turning on the camera exposure time control device, adjusting the parameter k of the signal processing circuit so that when the light intensity of the input photodiode is I 0 When the output exposure time is Δt 0 .

[0045] Step S4, obtaining the exposure time when the ambient light intensity changes rapidly, including: starting the device to be tested, the ambient light intensity I changes rapidly, inputting the light intensity I, outputting the exposure time Δt, and the grayscale of the captured image is always kept at g0 .

[0046] Embodiment 2: Exposure control device in three-dimensional digital image correlation (3D-DIC) measurement:

[0047] DIC (Digital Image Correlation) technology is an optical non-contact measurement method for measuring surface deformation of objects. By using a high-resolution camera to capture images of the object surface and performing correlation analysis on these images, DIC can accurately measure the displacement field and strain field of the object under conditions such as force and temperature changes. When performing DIC measurement on high-temperature solid surfaces, temperature fluctuations and thermal radiation fluctuations on the high-temperature solid surface will cause image overexposure during the measurement process.

[0048] See also Figure 3 and Figure 5 This embodiment describes an exposure control device for three-dimensional digital image correlation (3D-DIC) measurement. The device includes the following key components:

[0049] Dual light sources (one of the dual light sources in 3D-DIC 11 and the second of the dual light sources in 3D-DIC 12): The light source type can be an LED light source, a halogen lamp light source or a laser, and the specific selection depends on the measurement environment and the reflective characteristics of the surface of the deformable part to be measured.

[0050] Deformable part 2 to be tested: The material type is metal, composite material or other structural parts in high temperature environment. The surface is coated with random speckle pattern to facilitate the recognition and analysis of digital image correlation algorithm.

[0051] The dual cameras (the first dual camera 31 in 3D-DIC and the second dual camera 32 in 3D-DIC) respectively collect images of the deformable part 2 to be measured from different angles to form a three-dimensional image. The frame rate of the camera is 30fps to 3000fps, and the specific frame rate selection depends on the movement speed of the deformable part to be measured. The exposure time can be dynamically adjusted between 1 microsecond and 1 second.

[0052] Photodiode 4: The detection wavelength range is 400 to 1100 nanometers, suitable for visible light and near-infrared spectra. The response time of the photodiode should be less than 1 microsecond to ensure that it can respond to rapid changes in light intensity in a timely manner. The output voltage range is 0V to 5V, representing different light intensity signals.

[0053] Signal processing circuit 5: includes a division circuit module 51, an integration circuit module 52, and a pulse signal control module 53. The specific gain of the division circuit module is set according to the range of ambient light intensity. The pulse signal frequency range generated by the pulse signal control module is 1Hz to 1MHz, and the pulse width is proportional to the exposure time.

[0054] Computer and image acquisition system 6: used to acquire and process the images output by camera 3, and monitor and adjust the exposure time. The processor of the computer running the DIC algorithm should be a multi-core CPU or a device with GPU acceleration to ensure that large-scale image data can be processed quickly.

[0055] Implementation steps:

[0056] Build a test system: Build a test system based on the test method and test conditions used. Use dual cameras to synchronously capture images. Turn on the camera and set the camera frame rate f.

[0057] Get the best grayscale: Without turning on the exposure time control system, set the initial exposure time of the camera to Δt 0 , shooting without light intensity change (I=I 0 ) is the object being measured. The image grayscale obtained at this time is the optimal grayscale g 0 .

[0058] Adjust the parameters of the signal processing circuit: Turn on the camera exposure time control device and adjust the parameter k of the signal processing circuit so that when the light intensity of the input photodiode is I 0 When the output exposure time is Δt 0 .

[0059] To obtain the exposure time when the ambient light intensity changes rapidly: Start the device under test, such as Figure 2 In (b), the ambient light intensity I changes rapidly. Input light intensity I, output exposure time Δt, the grayscale of the captured image is always kept at g 0 The exposure time of the dual cameras is controlled by the generated pulse signals. The rising and falling edges of the pulse signals trigger the exposure of the cameras, ensuring that the exposure time of each frame matches the current light intensity, thereby avoiding overexposure or underexposure. For example, when the ambient light intensity increases, the voltage signal increases, and the voltage-controlled oscillator generates a narrower pulse signal, shortening the camera's exposure time to avoid overexposure.

[0060] In the process of obtaining the exposure time Δt, the signal undergoes the following transformation process:

[0061] Initial light intensity I 0 like Figure 2 As shown in (a), its intensity does not change with time.

[0062] The rapidly changing ambient light intensity I captured by the photodiode is Figure 2 As shown in (b), after entering the photodiode, the light intensity signal I is converted into a voltage signal U A .

[0063] Voltage signal U AEnter the division circuit module and get the voltage signal U B .U B = k / U A , whose size is inversely proportional to the light intensity signal and the exposure time required to obtain the best image grayscale (such as Figure 2 is proportional to (c)).

[0064] U B It is a continuously changing analog signal and cannot be used directly to control the exposure time. Through the integration circuit module, the analog signal is converted into a digital signal U that can control the pulse width. C ,like Figure 2 As shown in (d) in .

[0065] like Figure 2 In (e) and (f), the digital signal U C Input to the voltage-controlled oscillator, which converts the voltage signal into a pulse width modulated signal. The width of the pulse signal is proportional to the input voltage and represents the required exposure time. The rising and falling edges of the pulse correspond to the start and end of the exposure, respectively, thus achieving real-time exposure time adjustment.

[0066] Through this method, the system can quickly and adaptively adjust the exposure time to ensure that the image is not overexposed in a rapidly changing light intensity environment, thereby improving measurement accuracy.

[0067] Embodiment 3: Exposure control device in three-dimensional structured light profile measurement

[0068] Three-dimensional shape measurement technology, also known as 3D profilometry, is a method and technology that uses instruments to obtain external shape data of the measured object and establish a digital model. The structured light method uses a system composed of a projection device and a camera. The projection device projects specific light information onto the surface of the object, and the camera collects it synchronously. The position and depth information of the object are calculated based on the reflection changes of the light signal on the surface of the object, and then the entire three-dimensional shape of the object is restored. When the ambient light is too strong or changes dramatically, the strong background light may saturate the camera's sensor, resulting in overexposure of some areas and the inability to correctly obtain pattern information. In this case, the camera will not be able to accurately capture the true optical information of the object's surface.

[0069] See also Figure 4 and Figure 5 This embodiment describes an exposure control device for three-dimensional structured light topography measurement, which includes the following key components:

[0070] Projection device 7: used for projecting structured light carrying specific light information.

[0071] Object to be measured 8: an object for which three-dimensional shape measurement is required.

[0072] Dual cameras (one of the dual cameras 31 in 3D-DIC and the other of the dual cameras 32 in 3D-DIC): collect images of the deformable part 2 to be measured from different angles to form a three-dimensional image. The frame rate of the camera is 30fps to 3000fps, and the specific frame rate selection depends on the movement speed of the deformable part to be measured. The exposure time can be dynamically adjusted between 1 microsecond and 1 second.

[0073] Photodiode 4: The detection wavelength range is 400 to 1100 nanometers, suitable for visible light and near-infrared spectra. The response time of the photodiode should be less than 1 microsecond to ensure that it can respond to rapid changes in light intensity in a timely manner. The output voltage range is 0V to 5V, representing different light intensity signals.

[0074] Signal processing circuit 5: includes a division circuit module, an integration circuit module, and a pulse signal control module. The specific gain of the division circuit module is set according to the range of ambient light intensity. The pulse signal frequency range generated by the pulse signal control module is 1Hz to 1MHz, and the pulse width is proportional to the exposure time.

[0075] Computer and image acquisition system 6: used to acquire and process the images output by camera 3, and monitor and adjust the exposure time. The processor of the computer running the morphology measurement algorithm should be a multi-core CPU or a device with GPU acceleration to ensure that large-scale structured light data can be processed quickly.

[0076] Implementation steps:

[0077] Build a test system: Build a test system according to the test method and test conditions used. The projection device 7 projects a specific structured light onto the object 8 to be tested, and the dual cameras synchronously collect images. Turn on the camera and set the camera frame rate f.

[0078] Get the best grayscale: Without turning on the exposure time control system, set the initial exposure time of the camera to Δt 0 , shooting without light intensity change (I=I 0 ) is the object being measured. The image grayscale obtained at this time is the optimal grayscale g 0 .

[0079] Adjust the parameters of the signal processing circuit: Turn on the camera exposure time control device and adjust the parameter k of the signal processing circuit so that when the light intensity of the input photodiode is I 0 When the output exposure time is Δt 0 ,

[0080] Get the exposure time when the ambient light intensity changes rapidly: start the device under test, the ambient light intensity I changes rapidly, input the light intensity I, output the exposure time Δt, and the grayscale of the captured image is always kept at g 0The exposure time of the dual cameras is controlled by the generated pulse signals. The rising and falling edges of the pulse signals trigger the exposure of the cameras, ensuring that the exposure time of each frame matches the current light intensity, thereby avoiding overexposure or underexposure. For example, when the ambient light intensity increases, the voltage signal increases, and the voltage-controlled oscillator generates a narrower pulse signal, shortening the camera's exposure time to avoid overexposure.

[0081] Image processing: The computer and image acquisition system 6 collect and process images to reconstruct the three-dimensional shape of the object.

[0082] Through this method, the system can quickly and adaptively adjust the exposure time to ensure that the image is not overexposed in a rapidly changing light intensity environment. The method and device are particularly suitable for the morphology measurement of high-temperature objects. Since the radiation and light intensity of the object change greatly in a high-temperature environment, it is difficult to respond quickly using the traditional exposure control method based on image grayscale. Therefore, the method of the present invention can effectively solve this problem. By real-time monitoring of light intensity changes and adjusting the exposure time, the overexposure of the image can be greatly reduced and the measurement accuracy can be improved.

[0083] It can be understood that the above specific description of the present invention is only used to illustrate the present invention and is not limited to the technical solution described in the implementation of the calculation method of the present invention. Ordinary technicians in the field should understand that the present invention can still be modified or replaced by equivalents to achieve the same technical effect; as long as the requirements of the calculation method are met, they are all within the protection scope of the present invention.

Claims

1. A camera exposure time control method under high dynamic background light intensity changes, characterized by: The following steps are involved: Step S1, build a test system and set the camera frame rate f; Step S2, setting the initial exposure time of the camera to Δt0, photographing the object under test without light intensity change, the image grayscale obtained at this time is the optimal grayscale g0, and the light intensity input to the camera at this time is I0; Step S3, adjusting the signal processing circuit for controlling the camera exposure time so that when the input light intensity is I0, the signal processing circuit outputs an exposure time of Δt0; Step S4, start the device to be tested, the ambient light intensity I changes rapidly, the camera inputs the light intensity I, and the signal processing circuit outputs the exposure time Δt, so that the grayscale of the captured image is always maintained at g0.

2. A camera exposure time control device under high dynamic background light intensity changes, characterized by: It includes a signal processing circuit applied to the camera, the signal processing circuit includes a light intensity acquisition module, a division circuit module, an integration circuit module and a pulse signal control module which are sequentially connected; The light intensity acquisition module is used to detect the change of ambient light intensity in real time, and convert the light intensity signal into a voltage signal and send it to the division circuit module. The division circuit module is used to operate on the voltage signal. The voltage signal after operation is inversely proportional to the transformed ambient light intensity, and the voltage signal after operation is sent to the integration circuit module. The gain of the division circuit module can be adjusted according to the range of change of ambient light intensity. The integration circuit module is used to convert the voltage signal after operation into a digital signal that can control the pulse width, and send the digital signal to the pulse signal control module. The pulse signal control module generates a pulse signal according to the digital signal. The rising edge and falling edge of the pulse signal correspond to the start and end of camera exposure respectively, thereby realizing real-time camera exposure time adjustment.

3. The camera exposure time control device under high dynamic background light intensity change according to claim 1, characterized in that: The light intensity collection module is a photodiode.

4. The camera exposure time control device under high dynamic background light intensity change according to claim 3, characterized in that: The photodiode detects wavelengths in the range of 400 to 1100 nanometers, and the photodiode is installed in front of the camera.

5. The camera exposure time control device under high dynamic background light intensity change according to claim 2, characterized in that: The pulse signal control module is a voltage-controlled oscillator, which can convert a voltage signal into a pulse width modulation signal.

6. The camera exposure time control device under high dynamic background light intensity change according to claim 2, characterized in that: It also includes a computer and an image acquisition system. The computer is respectively connected to the image acquisition system and the pulse signal control module signal. The image acquisition system is used to acquire and process the image output by the camera and send the image to the computer. The pulse signal control module sends the pulse signal to the computer. The computer is used to process the image and monitor and adjust the exposure time according to the received pulse signal.

7. The camera exposure time control device under high dynamic background light intensity change according to claim 6, characterized in that: The processor of the computer is a multi-core CPU or a device with GPU acceleration.

8. An exposure control method in three-dimensional DIC measurement, characterized in that: The camera exposure time control device under high dynamic background light intensity changes as described in claim 3 includes the following steps: installing a light intensity acquisition module in front of the dual cameras to detect changes in ambient light intensity in real time; converting the detected light intensity signal into a voltage signal; processing the voltage signal through an analog operational amplifier circuit; using a pulse signal control module to generate a pulse signal; and controlling the camera exposure time through the pulse signal.

9. An exposure control method in three-dimensional structured light topography measurement, characterized in that: The camera exposure time control device under high dynamic background light intensity change as claimed in claim 6 comprises the following steps: a projection device projects specific structured light onto an object to be measured; a light intensity acquisition module is installed in front of dual cameras to detect changes in ambient light intensity in real time; the detected light intensity signal is converted into a voltage signal; the voltage signal is processed by an analog operational amplifier circuit; a pulse signal is generated by a pulse signal control module; the exposure time of the camera is controlled by the pulse signal; the dual cameras synchronously acquire images; a computer and an image acquisition system acquire and process images to reconstruct the three-dimensional shape of the object.

Images