An experimental device and method for analyzing imaging characteristics of fog environments

Abstract

The present application relates to the field of optical imaging and atmospheric optics, and particularly relates to an experimental device and method for analyzing imaging characteristics of fog environment. The device comprises, in sequence along the light path, a camera real shooting and light source subsystem, a fog environment generating subsystem, a fog generating and concentration control subsystem, a transmitted light receiving subsystem and a data control unit. The present application realizes time sequence synchronization of fog generation, image acquisition and spectrum acquisition through the data control unit, establishes a quantitative mapping relationship between the fog concentration and the image chroma and brightness, and provides accurate experimental data basis for verification and optimization of the image dehazing algorithm, and has the characteristics of strong repeatability and high data reliability.

Description

Technical Field

[0001] This invention relates to the fields of optical imaging and atmospheric optics, and in particular to an experimental apparatus and method for analyzing the imaging characteristics of fog environments. Background Technology

[0002] Fog, haze, and other aerosol media significantly affect the propagation of visible light. Incident light is simultaneously subjected to scattering, absorption, and multiple scattering reflections during propagation, leading to problems such as decreased contrast, blurred edges, reduced color saturation, brightness shift, and diminished target recognition capabilities in the images acquired by imaging systems. Particularly in applications such as autonomous driving, intelligent surveillance, machine vision, low-altitude sensing, photoelectric detection, and image dehazing algorithm verification, imaging degradation in foggy environments not only affects subjective visual quality but also directly impacts the accuracy of subsequent advanced tasks such as detection, segmentation, recognition, and ranging. Therefore, constructing an experimental platform that can stably simulate foggy environments and quantitatively analyze imaging degradation patterns under controllable and repeatable indoor experimental conditions has become a crucial research problem in the interdisciplinary field of optical imaging and atmospheric optics. Existing research shows that relying solely on outdoor natural foggy weather for image acquisition often makes it difficult to accurately control fog concentration, particle size distribution, ambient temperature and humidity, and lighting conditions, resulting in poor experimental repeatability, severe variable coupling, and hindering the establishment of a reliable mapping relationship between fog concentration and image degradation parameters. Therefore, related technologies are gradually shifting towards building controlled fog environment simulation devices indoors, and conducting experiments by artificially generating fog media and combining them with imaging equipment.

[0003] In the prior art, patent document CN105068158A discloses a meteorological optical visibility observation environment simulation device. This scheme adopts a sealed simulation chamber structure and is equipped with a video monitoring camera, temperature sensor, humidity sensor, air pressure sensor, and calibration equipment inside the chamber. Simultaneously, an air supply and circulation system is formed through air supply ducts, return air ducts, air filters, and ultrasonic humidifiers, thereby constructing a low-visibility environment inside the chamber for the calibration and testing of meteorological optical visibility observation equipment. The technical contribution of this document lies in two aspects: firstly, the combined structure of a positive static pressure chamber, an environmental simulation chamber, and a negative static pressure chamber improves the control capability of the chamber environment; secondly, the combination of humidification and circulating air supply enables artificial control of meteorological conditions inside the simulation chamber, providing an experimental basis for testing optical observation equipment under low visibility conditions. In other words, this document demonstrates that constructing a controllable fog environment in a closed or semi-closed space and collecting data using cameras and environmental sensors is an existing technical approach in this field.

[0004] However, further analysis of CN105068158A reveals that its main focus is on simulating the visibility observation environment and calibrating the observation equipment. Its core objective is to establish an observation platform under low-visibility meteorological conditions, rather than conducting refined research on the mechanism of image color degradation. While the document includes video surveillance cameras and several environmental sensors, it does not design a device to address the quantitative relationship between image chroma, brightness, and fog concentration, nor does it disclose the use of a standard light source, standard color chart, diffuse scattering homogenization component, and transmission spectral detection unit to construct a unified measurement system. In other words, while the document can provide a fog environment, it cannot directly solve the following technical problems: how to simultaneously obtain transmission information characterizing the physical transmission properties of the fog medium and color information characterizing the visual degradation properties of the image in the same fog field; and how to establish a quantifiable correspondence between fog concentration changes and image chroma and brightness changes using standardized color targets. Therefore, this type of scheme, primarily based on visibility simulation, still suffers from insufficient standardization, inadequate color analysis capabilities, and difficulty in integrating physical and perceived quantities when used for image dehazing algorithm verification, color transmission law modeling, and research on fog environment imaging characteristics.

[0005] On the other hand, patent document CN104902153A discloses a color correction method for a multispectral camera. The optical system of this document consists of an integrating sphere light source, a transmissive 24-color standard color chart, a light-blocking plate, a collimator, and a spectroradiometer. Its basic idea is to use the standard color chart and spectroradiometer to obtain the spectral radiance and chromaticity coordinates of each color patch, and then use this information to perform color correction on the multispectral camera. The value of this document lies in its revelation of the technical approach of establishing the relationship between image color response and spectral quantities through a standard light source, standard color chart, and spectral measurement device, providing a feasible solution for subsequent camera color calibration and color consistency evaluation. From the perspective of this case, this document demonstrates that using a standard color chart / color plate as a color reference and establishing color quantification relationships through spectral measurement is a common practice in related fields, representing an important prior art in the direction of color measurement and image correction.

[0006] However, the application background of CN104902153A is mainly color calibration of multispectral cameras in the field of aerospace remote sensing. Its focus is on camera calibration under static standard conditions in the laboratory, not on imaging degradation research in foggy scattering media. It is particularly noteworthy that the procedure in this document explicitly demonstrates the sequential use of the multispectral camera and the spectroradiometer: first, the camera is set up at the output port of the collimator for imaging, then the camera is removed and the spectroradiometer is used to collect the spectral and chromaticity data of the standard color patch. In other words, this document establishes a static, sequential, and substitutional measurement process, rather than simultaneously acquiring image data and transmission spectral data under the same time, scattering environment, and illumination conditions. This technical approach is feasible in ordinary color calibration scenarios, but once it enters a fog environment with continuously changing concentrations, sequential acquisition introduces significant limitations: First, fog concentration changes over time, and the medium states corresponding to two consecutive samples are often different, resulting in a lack of strict correspondence between image data and spectral data; second, the literature does not consider the impact of temperature and humidity fluctuations, scattered light, optical path attenuation, and spatial inhomogeneity within the fog field on the imaging results; third, the literature also does not disclose the fog chamber, fog generator, concentration control mechanism, and fog field homogenization structure used for indoor fog environment simulation. Therefore, although this type of scheme, which mainly relies on static color correction, can solve the camera color calibration problem, it cannot yet meet the research needs of simultaneously acquiring physical transmittance and visual color rendering characteristics and establishing quantitative mappings in fog environments.

[0007] In summary, existing technologies have at least the following shortcomings: First, while technologies like CN105068158A can construct controlled fog environments, they primarily serve visibility observation and equipment calibration, lacking specific consideration for image color degradation mechanisms and failing to form a comprehensive color measurement system comprised of standard light sources, standard color charts, and transmission spectral detection. Second, although technologies like CN104902153A introduce standard color charts and spectroradiometers, providing a good foundation for color correction, their application is limited to static calibration scenarios and employs a sequential acquisition method, making them unsuitable for adapting to continuous changes in fog concentration. First, existing methods cannot simultaneously obtain transmission spectral information that characterizes the light transmission state of the fog medium and image color information that characterizes the color degradation state of the target within the same fog field. This makes it difficult to establish a precise quantitative relationship between fog concentration and chromaticity / brightness. Second, current technologies are insufficient in their collaborative design regarding illumination uniformity, imaging target standardization, data synchronization, and experimental repeatability, failing to meet higher-level experimental requirements such as image dehazing algorithm verification, research on visual perception models in fog environments, and analysis of imaging color transmission patterns. Therefore, a new experimental device and method for analyzing the imaging characteristics of fog environments is urgently needed to achieve synchronous collaboration between standardized illumination, standardized color targets, transmission spectral reception, and industrial camera imaging in a controlled fog environment. This would provide a reliable and repeatable experimental basis for the quantitative mapping between fog concentration and image chromaticity / brightness. Summary of the Invention

[0008] The technical objective of this invention is to address the problems in existing fog environment imaging experiments, such as discontinuous fog concentration control, asynchronous image acquisition and spectral measurement, lack of standardized chromaticity reference, and difficulty in establishing a quantitative relationship between fog concentration and image chromaticity and brightness. This invention provides an experimental device and method for analyzing the imaging characteristics of fog environments, enabling the simultaneous acquisition of transmission spectral data and standard color chart imaging data at different fog concentrations under controlled indoor conditions. This allows for precise analysis of imaging degradation patterns in fog environments and provides a reliable experimental platform and data foundation for the verification, optimization, and visual perception enhancement research of image dehazing algorithms.

[0009] Firstly, in order to achieve the above-mentioned objectives, the present invention adopts the following technical solution:

[0010] An experimental apparatus for analyzing the imaging characteristics of fog environments includes a camera imaging and light source subsystem, a fog environment generation subsystem, a fog generation and concentration control subsystem, a transmitted light receiving subsystem, and a data control unit.

[0011] The fog environment generation subsystem includes a fog chamber, the camera shooting and light source subsystem is located on one side of the fog chamber, the transmitted light receiving subsystem is located on the other side of the fog chamber, and the fog generation and concentration control subsystem is connected to the fog chamber.

[0012] The camera shooting and light source subsystem includes an industrial camera, a zoom lens, a filter, a standard light source, and a first diffuse light distribution plate. The industrial camera, zoom lens, and filter are connected in sequence. The standard light source is positioned towards the fog chamber. The first diffuse light distribution plate is positioned on the light output path of the standard light source.

[0013] The fog environment generation subsystem also includes a second diffuse light equalization plate set on the outer wall of the fog chamber near the camera shooting and light source subsystem, a standard color card set on the inner wall of the fog chamber near the transmission light receiving subsystem, a fan group set at the bottom of the fog chamber, and a temperature and humidity sensor set on the inner wall of the fog chamber. The standard color card is staggered with the transmission measurement main optical path.

[0014] The transmitted light receiving subsystem includes an optical fiber coupler and an optical fiber spectrometer. The optical fiber coupler is connected to the optical fiber spectrometer, and the receiving end of the optical fiber coupler is aligned with the direction of the standard light source.

[0015] The standard light source, the first diffuse light-averaging plate, the second diffuse light-averaging plate, the fog chamber, and the fiber optic coupler together form the transmission measurement optical path. The industrial camera forms an imaging optical path for the standard color card through the zoom lens and the filter. The data control unit is electrically connected to the fog generation and concentration control subsystem, the industrial camera, and the fiber optic spectrometer, respectively, and is used to synchronously acquire the transmission spectral data and the color image data of the standard color card under the same fog state during the continuous change of fog concentration.

[0016] Preferably, after the industrial camera, zoom lens, and filter are connected, their focal plane is set on the standard color card inside the fog chamber.

[0017] Preferably, the data control unit is used to achieve time-synchronous control of fog generation, image acquisition, and spectral acquisition.

[0018] Preferably, the standard color card is fixed to the area on the inner wall of the fog chamber near the side of the transmitted light receiving subsystem, and is offset along a direction perpendicular to the main optical path of the transmission measurement.

[0019] Preferably, the fan assembly is located at the bottom of the fog chamber to promote uniform diffusion of fog within the fog chamber and to assist in emptying the fog after the experiment.

[0020] Preferably, the standard light source is a standard white light source, and the first diffuse scattering plate and the second diffuse scattering plate are used to reduce illumination non-uniformity and improve the consistency between transmission measurement and color imaging.

[0021] Secondly, the present invention also provides a method for analyzing the imaging characteristics of foggy environments, using the aforementioned experimental apparatus, comprising the following steps:

[0022] S1. Prepare the experimental environment: Clean the inside of the fog chamber and adjust the temperature and humidity inside the fog chamber; test and calibrate the instruments in the camera shooting system, the light source subsystem, and the transmission light receiving subsystem, and adjust the transmission measurement optical path and the imaging optical path.

[0023] S2. Prepare mist medium: Set the target medium concentration of the mist generation and concentration control subsystem, and add the prepared medium solution to the mist generation and concentration control subsystem.

[0024] S3. Synchronous data acquisition: Turn on the standard light source and data control unit, start the fog generation and concentration control subsystem to fill the fog chamber with fog medium, and at the same time start the industrial camera and fiber optic spectrometer to synchronously record the transmission spectrum data and standard color card color image data under the same fog condition.

[0025] S4. End the experiment: Turn off the standard light source and data control unit, and turn on the ventilation device of the fog generation and concentration control subsystem and fog chamber for exhaust.

[0026] Preferably, in step S3, the fog medium is continuously filled according to a preset concentration change curve, so that the collection process covers a continuous state from no fog to dense fog.

[0027] And / or, in step S3, the data control unit calculates the transmittance at different wavelengths based on the spectral data collected by the fiber optic spectrometer, and calculates the chromaticity coordinates and lightness values ​​of each color patch based on the standard color chart image collected by the industrial camera;

[0028] And / or, the acquisition termination condition of step S3 is: the transmission spectrum in the fog chamber tends to stabilize and the standard color card image acquired by the industrial camera cannot identify the preset color block information.

[0029] Preferably, the data control unit establishes a quantitative mapping relationship between fog concentration and chromaticity and brightness based on the transmittance, chromaticity coordinates and brightness values ​​under different fog conditions.

[0030] Preferably, the chromaticity coordinates and lightness values ​​are characterized using CIELab color space parameters.

[0031] This invention constructs a collaborative experimental system consisting of a standard light source, a diffuse scattering light distribution plate, a fog chamber, a standard color chart, a fiber optic spectrometer, an industrial camera, and a data control unit. Under the same controlled fog field, the same lighting reference, and the same time conditions, it simultaneously acquires transmission spectral data and target color image data. This allows for a unified characterization and correlation analysis of the physical influence of fog on the light transmission process and its visual impact on image color performance. Compared to existing technologies that suffer from unstable fog environment control, asynchronous image acquisition and spectral measurement, non-standard color references, and insufficient experimental repeatability, this invention can continuously and stably simulate the dynamic change process from light fog to dense fog, accurately record the chromaticity coordinates, brightness changes, and transmittance attenuation laws of the standard color chart under different fog concentrations, and thus establish a quantitative mapping relationship between fog concentration and image chromaticity and brightness. Because this invention uses a standardized light source and a standard color chart as a unified reference, and achieves time-consistent acquisition of multimodal data through synchronous control, it can significantly improve the repeatability, comparability, and quantitative analysis accuracy of experimental results, providing a reliable basis for revealing the imaging degradation mechanisms such as color distortion, brightness attenuation, and contrast reduction under foggy conditions. Simultaneously, this device and method can also provide real, continuous, and calibrable experimental data support for the study of image dehazing algorithms, color restoration algorithms, visual enhancement models, and atmospheric scattering imaging mechanisms. This eliminates the reliance on random natural fog fields for algorithm verification, improves the stability of the testing process and the credibility of the evaluation results, thus possessing high scientific research and engineering application value. Attached Figure Description

[0032] Figure 1 This is a schematic block diagram of an experimental device for analyzing the imaging characteristics of fog environments according to the present invention.

[0033] Figure 2 This is a real-life photograph of the inside of the fog chamber and the standard color chart during the experiment of this invention, showing the imaging state of the standard color chart under some different fog concentrations.

[0034] Figure 3 This is a graph showing the change in fog concentration during the experiment of this invention. Figure 3 (a) is the original transmission spectrum. Figure 3 In the middle (b), the calculated transmittance changes over time.

[0035] Figure 4 This is a schematic diagram illustrating the quantitative mapping relationship between fog concentration and chromaticity and lightness established using the experimental apparatus and method of this invention (by extracting the CIELab chromaticity coordinates (a, b) and lightness value L of each color patch on the standard color chart 12 under different fog concentrations). Figure 4 (a) Plot the curve showing the relationship between lightness after subtracting the dark reference and transmittance t. Figure 4 (b) shows the relationship between the chromaticity vector magnitude and transmittance t.

[0036] In the diagram, 1-Camera shooting and light source subsystem, 2-Fog environment generation subsystem, 3-Fog generation and concentration control subsystem, 4-Transmitted light receiving subsystem, 5-Industrial camera, 6-Zoom lens, 7-Filter, 8-Standard light source, 9-First diffuse light distribution plate, 10-Fog chamber, 11-Second diffuse light distribution plate, 12-Standard color chart, 13-Fan assembly, 14-Temperature and humidity sensor, 15-Fog controller, 16-Fog generator, 17-Fiber optic coupler, 18-Fiber optic spectrometer, 19-Data control unit. Detailed Implementation

[0037] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the following embodiments are for illustrative purposes only and are not intended to limit the scope of protection of the present invention. Any equivalent substitutions or conventional adjustments made to the structural form, connection relationship, control method, and test parameters under the concept of the present invention should fall within the scope of protection of the present invention.

[0038] This invention provides an experimental apparatus and method for analyzing the imaging characteristics of fog environments. It is used to continuously simulate the fog concentration change process in a controlled indoor fog environment and simultaneously acquire transmission spectrum data and standard target imaging data, thereby establishing a quantitative relationship between transmittance, chromaticity, and brightness in fog environments.

[0039] I. Example 1: Construction of the Experimental Apparatus

[0040] like Figure 1 As shown, an experimental apparatus for analyzing the imaging characteristics of fog environments in this embodiment includes a camera shooting and light source subsystem 1, a fog environment generation subsystem 2, a fog generation and concentration control subsystem 3, a transmitted light receiving subsystem 4, and a data control unit 19.

[0041] 1. Camera shooting and light source subsystem 1

[0042] The camera shooting and light source subsystem 1 includes an industrial camera 5, a zoom lens 6, a filter 7, a standard light source 8, and a first diffuse light distribution plate 9.

[0043] in:

[0044] (1) The industrial camera 5 is used to acquire two-dimensional color images of the standard color chart 12 inside the fog chamber 10. The industrial camera 5 is preferably an area array color industrial camera with a resolution of not less than [missing information]. Bit depth not less than 8 bits, frame rate adjustable from 1 to 30fps, exposure time is ~50ms adjustable. In this embodiment, the industrial camera 5 is fixedly mounted on a camera bracket on the outside of the front end of the fog chamber 10, and the optical axis of the lens is basically parallel to the central axis of the fog chamber 10.

[0045] (2) The zoom lens 6 is connected to the front end of the industrial camera 5 and is used to adjust the field of view and magnification. The focal length of the zoom lens 6 is preferably adjustable from 12 to 50 mm, and the aperture is preferably adjustable from F1.8 to F16. In this embodiment, after the zoom lens 6 is adjusted, the standard color card 12 occupies 60% to 85% of the imaging area in the image, so as to take into account both the color block resolution and the overall background of the fog field.

[0046] (3) The filter 7 is disposed at the front end of the zoom lens 6 or between the lens and the camera to suppress ambient stray light and reduce the impact of high-brightness reflection on imaging stability. The filter 7 can be a neutral density filter, an ultraviolet cut-off filter, or a narrowband filter. In this embodiment, an ultraviolet cut-off visible light transmission filter is preferably used to reduce the impact of non-target wavelengths on image colorimetric calculation.

[0047] (4) A standard light source 8 is positioned in front of the fog chamber 10 to provide stable standard illumination for the interior of the fog chamber 10. In this embodiment, the standard light source 8 is preferably a D65 approximate standard white light source, and the correlated color temperature is preferably... The color rendering index is preferably not less than 95, and the output light power stability is preferably not less than [value missing]. The standard light source 8 can be implemented using an integrating sphere, a standard LED planar light source, or a halogen tungsten lamp with a constant current drive.

[0048] (5) The first diffuse light equalization plate 9 is disposed between the standard light source 8 and the fog chamber 10 to equalize the emitted light from the standard light source 8 and reduce the uneven lighting caused by point light sources or local high-brightness areas. In this embodiment, the first diffuse light equalization plate 9 is preferably a milky white high-transmittance diffuser plate with a thickness of 2 to 5 mm and a transmittance of 40% to 80%.

[0049] The industrial camera 5, zoom lens 6, and filter 7 are connected in sequence to form the imaging link; the standard light source 8 and the first diffuse light-diffusing plate 9 constitute the illumination link. The illumination link and the imaging link share the same working space on the front side of the fog chamber 10, but do not mechanically interfere with each other.

[0050] 2. Fog Environment Generation Subsystem 2

[0051] The fog environment generation subsystem 2 includes a fog chamber 10, a second diffuse light distribution plate 11, a standard color card 12, a fan group 13, and a temperature and humidity sensor 14.

[0052] (1) The fog chamber 10 is a closed or semi-closed enclosure used to provide a fog environment and optical path transmission space. The fog chamber 10 is preferably made of transparent glass, acrylic sheet, or optical-grade transparent polycarbonate sheet. To facilitate stable control of the optical path length, the length of the fog chamber 10 along the optical path direction is preferably 400–1000 mm, the width is preferably 300–800 mm, and the height is preferably 300–800 mm. In this embodiment, the fog chamber 10 adopts an internal dimension of… The transparent enclosure has a light path length of 600mm. The top of the mist chamber 10 is equipped with an openable and closable maintenance cover, and the bottom is equipped with a drain or collection tank for collecting condensate.

[0053] (2) The second diffuse light-diffusing plate 11 is disposed on the outer wall of the fog chamber 10 near the camera and the light source subsystem 1. It is preferably used in conjunction with the first diffuse light-diffusing plate 9 to further reduce the illuminance non-uniformity at the fog chamber entrance and reduce the forward scattering bias caused by local strong illumination. In this embodiment, the second diffuse light-diffusing plate 11 is fixed to the outer side of the front wall of the fog chamber 10. Its material can be the same as that of the first diffuse light-diffusing plate 9, or a diffuser plate with slightly higher transmittance can be used to avoid excessive loss of incident energy.

[0054] (3) A standard color chart 12 is disposed on the inner wall of the fog chamber 10 near the side of the transmitted light receiving subsystem 4, serving as the photographed target and providing standardized color and reflectivity references. The standard color chart 12 is preferably a 24-color standard color chart, but an extended color chart containing neutral gray levels and high / low saturation color blocks can also be used. In this embodiment, the standard color chart 12 is pasted on the upper part of the rear inner wall of the fog chamber 10, with its central area located in the center of the field of view of the industrial camera 5. The standard color chart 12 is offset along a direction perpendicular to the main optical path of the transmission measurement to avoid blocking the transmitted light from directly entering the measurement channel of the fiber optic coupler 17.

[0055] (4) The fan assembly 13 is located at the bottom of the fog chamber 10 to promote rapid diffusion and uniform mixing of fog within the chamber and to facilitate rapid fog removal after the experiment. The fan assembly 13 can consist of 2 to 4 DC axial fans or centrifugal fans. In this embodiment, the fan assembly 13 uses 2 low-speed axial fans, with a preferred airflow of 20 to 60 CFM per fan and adjustable speed. During data acquisition, the fan assembly 13 operates at low speed or intermittently to avoid large-scale eddies affecting the stability of the color chart image; during fog removal, the fan assembly 13 operates continuously at high speed.

[0056] (5) The temperature and humidity sensor 14 is installed in the middle of the inner wall of the fog chamber 10 or near the standard color card 12 to monitor the internal environmental parameters of the fog chamber 10 in real time, serving as the basis for experimental consistency control and fog de-fogging termination judgment. The preferred temperature measurement accuracy of the temperature and humidity sensor 14 is... Within this range, the preferred accuracy for relative humidity measurement is [missing information]. Within.

[0057] 3. Fog Generation and Concentration Control Subsystem

[0058] The fog generation and concentration control subsystem 3 includes a fog controller 15 and a fog generator 16.

[0059] (1) The fog generator 16 is used to generate fog droplets and introduce them into the fog chamber 10 through a pipe. The fog generator 16 can be generated by ultrasonic atomization, two-fluid spraying, or heating evaporation and condensation. In this embodiment, an ultrasonic atomizer is preferably used, and the average droplet size is preferably 1 to 20 mm. Using deionized water as the atomizing medium avoids solute residue forming crystals on the fog chamber walls, which would affect light transmission.

[0060] (2) The fog controller 15 is connected to the fog generator 16 and is used to control the start / stop, power, fog output, and exhaust valve status of the atomizer. The fog controller 15 may also include a flow regulating valve, a fog output regulating module, a timing module, and a ventilation control module. In this embodiment, the fog controller 15 can control the fog input in a stepped, linear, or segmented linear manner according to a preset time program. Preferably, it is set to complete the continuous fogging process from low fog to high fog within 10 to 80 seconds.

[0061] 4. Transmitted light receiving subsystem

[0062] The transmitted light receiving subsystem 4 includes an optical fiber coupler 17 and an optical fiber spectrometer 18.

[0063] (1) The fiber optic coupler 17 is disposed on the rear exterior of the fog chamber 10, with its receiving end facing the standard light source 8, and is used to receive the transmitted light after passing through the first diffuse light equalization plate 9, the second diffuse light equalization plate 11, and the fog medium inside the fog chamber 10. The fiber optic coupler 17 preferably has a collimating lens assembly and an adjustable angle bracket to accurately calibrate the receiving direction. In this embodiment, the receiving end of the fiber optic coupler 17 is substantially coaxial with the center of the standard light source 8 and slightly lower than the plane where the standard color card 12 is located, thereby forming a transmission measurement main optical path independent of the imaging area of ​​the standard color card.

[0064] (2) The fiber optic spectrometer 18 is connected to the fiber optic coupler 17 and is used to collect the transmission spectrum in the visible light band of 400-780nm. In this embodiment, the spectral resolution of the fiber optic spectrometer 18 is preferably no higher than 2nm, the integration time is preferably adjustable from 1 to 100ms, and the sampling frequency is preferably synchronized with the industrial camera 5 or an integer multiple thereof.

[0065] 5. Data Control Unit 19

[0066] The data control unit 19 is electrically connected to the fog controller 15, fog generator 16, industrial camera 5, and fiber optic spectrometer 18, respectively, to achieve unified scheduling and time-series synchronization control of fog generation, image acquisition, and spectral acquisition. The data control unit 19 can adopt an industrial computer, a host computer with a data acquisition card, an embedded controller, or a combination of a PLC and a host computer architecture. In this embodiment, the data control unit 19 is preferably a computer running a self-written control program and has the following functions:

[0067] Set the total sampling time, sampling interval, and atomization program;

[0068] Start the standard light source 8 preheating and stabilization timing;

[0069] Simultaneously trigger sampling by industrial camera 5 and fiber optic spectrometer 18;

[0070] Record timestamps, temperature, humidity, and atomization status;

[0071] Automatically saves the original images, original spectra, and environmental parameters;

[0072] Calculate the transmittance, chromaticity coordinates, and lightness value.

[0073] II. Example 2: Device Installation and Calibration

[0074] To ensure the repeatability of the experiment, the apparatus was installed and calibrated before the formal test.

[0075] 1. Mechanical installation

[0076] Place the fog chamber 10 on the vibration-damping test bench, arranging the standard light source 8, the first diffuse light distribution plate 9, the second diffuse light distribution plate 11, the fog chamber 10, and the fiber optic coupler 17 sequentially along the straight optical path. Install the industrial camera 5 above or to the side of the fog chamber 10, ensuring its lens can completely capture the standard color chart 12. Adjust the positions of the camera bracket and the fiber optic coupler bracket to ensure that the camera's field of view does not obstruct the main transmission optical path.

[0077] 2. Optical path adjustment

[0078] With the standard light source 8 turned on in a fog-free state inside the fog chamber 10, the positions of the first diffuse light distribution plate 9 and the second diffuse light distribution plate 11 are adjusted to control the spatial non-uniformity of illumination on the surface of the standard color card 12 within a reasonable range. Initial adjustment can be performed by taking the average brightness of the blank background area around the standard color card 12, or a temporary whiteboard can be added to check the uniformity of illumination.

[0079] Adjust the focal length, aperture, and focus ring of the zoom lens 6 so that the focal plane of the industrial camera 5 falls on the surface of the standard color chart 12, obtaining a color chart image with sharp edges and no obvious ghosting or saturation areas. Preferably, the image grayscale peak is controlled to be between 60% and 80% of the camera's full scale.

[0080] Adjust the angle and position of the fiber optic coupler 17 to ensure that the transmitted light signal received by the fiber optic spectrometer 18 is stable and unsaturated in a fog-free state. If necessary, adjust the signal intensity by changing the integration time or adding a neutral density attenuator.

[0081] 3. Camera and spectrometer calibration

[0082] (1) Camera calibration:

[0083] Perform black level correction and white balance fixation on the industrial camera 5 in fog-free conditions. It is preferable to disable automatic exposure, automatic white balance, and automatic gain, and switch to manual fixation mode to prevent data incomparability caused by the camera's automatic adjustments under different fog conditions.

[0084] (2) Spectral baseline calibration:

[0085] The initial transmission spectrum of standard light source 8 was collected under fog-free conditions after transmission through a double diffuse scattering homogenizing plate and the air medium of the fog chamber, and denoted as . Dark noise spectra were collected under conditions of standard light source 8 being turned off or in a state of complete darkness, and denoted as [missing information]. The effective transmission spectrum at any subsequent time is denoted as:

[0086] ;

[0087] The effective reference spectrum for fog-free conditions is:

[0088] ;

[0089] in, For wavelength, The sampling time.

[0090] 4. Setting initial environmental conditions

[0091] Before the experiment began, the laboratory ambient temperature was controlled at [temperature range]. ~ The relative humidity is controlled between 35% and 55% RH. The initial temperature inside the fog chamber 10 is preferably set to... The relative humidity is preferably set to If condensation exists on the inner wall of the fog chamber 10, it should be wiped with a lint-free cloth and left to stand for 10-20 minutes before the formal test to restore its transparent state.

[0092] III. Example 3: Method for analyzing imaging characteristics in foggy environments

[0093] Using the experimental apparatus described in Examples 1 and 2 above, the imaging characteristics of fog environments were analyzed. This method includes the following steps.

[0094] Step S1: Prepare the experimental environment

[0095] Clean the inside of the fog chamber 10 and check the surface of the standard color card 12 for water stains, dust or scratches; check the surface of the first diffuse light equalization plate 9 and the second diffuse light equalization plate 11 for local contamination; check the receiving port of the fiber optic coupler 17 for cleanliness.

[0096] Turn on the standard light source 8 and preheat it for 10-20 minutes to stabilize its light emission. Start the data control unit 19 and perform a connection test on the industrial camera 5, fiber optic spectrometer 18, and temperature and humidity sensor 14 to confirm normal communication. Record the baseline image and baseline spectral data under fog-free conditions.

[0097] Step S2: Prepare the mist medium

[0098] Deionized water is added to the storage container of the mist controller 15 or the mist generator 16. In this embodiment, water with a conductivity of less than 10 is preferably used. Deionized water is used to reduce the deposition of residual ions on the walls of the nebulizer and fog chamber. If it is necessary to study the effect of different media types on imaging characteristics, a low-mass-fraction salt solution or glycerol aqueous solution can also be used as the nebulizing medium, but the media composition should be kept stable during the experiment and described separately in the instruction manual.

[0099] The target fogging program of the fog controller 15 is set. In this embodiment, a continuous fogging program of 0-65s is preferred, with the first 10s being the rapid fogging stage, 10-35s being the medium-speed fogging stage, and 35-65s being the slow approaching saturation stage. This allows the transmittance and image degradation process to change continuously, which is convenient for subsequent fitting.

[0100] Step S3: Synchronously collect data

[0101] After starting the synchronous acquisition program of the data control unit 19, it runs according to the following timing sequence:

[0102] At that time, baseline synchronous sampling of industrial camera 5 and fiber optic spectrometer 18 is initiated;

[0103] At time s, the fog generator 16 begins to input fog into the fog chamber 10;

[0104] During the data collection, the industrial camera 5 photographs the standard color chart 12 at a fixed frame rate, and the fiber optic spectrometer 18 records the transmission spectrum at a fixed sampling frequency.

[0105] Temperature and humidity sensor 14 synchronously records the internal environmental parameters of fog chamber 10;

[0106] The data control unit 19 assigns a unified timestamp to each frame of image and its corresponding spectrum.

[0107] In this embodiment, the sampling frame rate of the industrial camera 5 is preferably set to 1fps to 5fps, and the sampling frequency of the fiber optic spectrometer 18 is preferably set to the same as that of the industrial camera 5, or set to 5Hz and matched according to the nearest time stamp in post-processing. The exposure parameters remain constant throughout the experiment.

[0108] The data acquisition termination condition can be set to satisfy any one or more of the following conditions simultaneously:

[0109] The change in the transmission spectrum is less than a preset threshold within 5 consecutive sampling periods;

[0110] The preset color blocks in the standard color chart 12 images captured by industrial camera 5 can no longer be reliably identified;

[0111] The fog controller 15 reaches the set maximum fogging time;

[0112] Temperature and humidity have reached the preset safety limits.

[0113] Step S4: End of Experiment and Ventilation

[0114] Stop the fog generator 16 from operating, turn off the standard light source 8, and turn on the fog controller 15 exhaust valve and fan group 13 in high-speed mode to force ventilation into the fog chamber 10. After the image in the fog chamber 10 becomes clear again and the temperature and humidity return to near their initial state, turn off the device and save all original data.

[0115] IV. Example 4: Image and Spectral Data Processing

[0116] To establish a quantitative relationship between fog concentration and imaging chromaticity and brightness, the data collected in step S3 is processed as follows.

[0117] 1. Transmittance Calculation

[0118] For any given moment The original transmission spectrum After dark noise subtraction, the wavelength-dependent transmittance is calculated using the following formula:

[0119] ;

[0120] in, For a moment ,wavelength Transmittance at that location.

[0121] To obtain the scalar transmittance of a specific characteristic wavelength band, three typical wavelengths—450nm, 550nm, and 650nm—can be selected to calculate the transmittance in the blue, green, and red bands, respectively; alternatively, a weighted average of visible light can be used to obtain the comprehensive color transmittance.

[0122] ;

[0123] in, For a moment Overall color transmittance, The weighting function can be an equal-weighting function or a light efficiency function matched to the standard observer. and These are the lower and upper limits of the visible band, respectively.

[0124] 2. Color chart area extraction

[0125] In the haze-free baseline image, the Region of Interest (ROI) for each color patch in the standard color chart 12 is selected manually or automatically. To reduce the impact of edge blending, the ROI of each color patch is preferably selected from its interior 50% to 70% area. The ROI locations in the haze-free image are mapped to subsequent time-series images, and fine-tuning is performed as necessary using template matching or corner point localization.

[0126] 3. Color space conversion

[0127] The RGB mean value of each ROI at each time step is extracted and converted to the CIELab color space to obtain the brightness value. chromaticity components and The magnitude of the composite chromaticity vector can be expressed as:

[0128] ;

[0129] in, For a moment The overall chromaticity amplitude.

[0130] 4. Dark reference brightness correction

[0131] When the fog concentration is high, the image brightness includes not only the target reflection component but also the background brightness formed by backscattering from the fog medium. To reduce this influence, a near-black color patch from standard color chart 12 or a separate black reference patch can be selected, and its brightness at various times can be calculated as a dark baseline. The corrected brightness of the target color patch is denoted as:

[0132] ;

[0133] in, This represents the effective brightness after subtracting the dark reference value.

[0134] 5. Fitting the relationship between transmittance and chromaticity / lightness

[0135] The overall color transmittance at each moment With comprehensive chromaticity amplitude , correct brightness A mapping relationship is established by matching the data. Based on the distribution of the experimental data, an exponential model, logarithmic model, power function model, or piecewise model can be used for fitting. In this embodiment, the following form is preferred for fitting:

[0136] ;

[0137] in, Can represent or , , and For the fitting parameters, This refers to the overall color transmittance.

[0138] By fitting the results, we can obtain the attenuation pattern of different color blocks in a foggy environment and compare their response differences under different transmittance conditions.

[0139] V. Specific Application Examples

[0140] The following description, in conjunction with the accompanying drawings, provides further examples of specific applications of the present invention. These examples illustrate the application process and technical effects of the device and method of the present invention in the analysis of imaging characteristics in foggy environments, but do not constitute a limitation on the scope of protection of the present invention.

[0141] (I) Application Example 1: Experiment on continuous acquisition of fog environment imaging degradation based on the device of the present invention

[0142] 1. Experimental Objective

[0143] use Figure 1 The experimental setup shown for analyzing the imaging characteristics of fog environments continuously generates fog of different concentrations in a controlled indoor fog environment, and collects data synchronously at each concentration.

[0144] Real-world images of a standard color chart under fog conditions;

[0145] Transmission spectrum passing through the fog chamber;

[0146] This establishes a quantitative relationship between changes in fog concentration and the attenuation of image chroma and brightness, and verifies the technical effectiveness of the device of the present invention in terms of synchronization, continuity, standardization, and repeatability.

[0147] 2. Experimental setup and conditions

[0148] This experiment uses Figure 1 The device shown includes a camera shooting and light source subsystem 1, a fog environment generation subsystem 2, a fog generation and concentration control subsystem 3, a transmitted light receiving subsystem 4, and a data control unit 19.

[0149] 2.1 Main Equipment Parameters

[0150] Industrial Camera 5: Color Industrial Camera, Resolution 8-bit output, fixed exposure mode;

[0151] Zoom Lens 6: Focal length 25mm;

[0152] Filter 7: Visible light passband filter;

[0153] Standard light source 8: D65 is a near-standard white light source with a color temperature of approximately 6500K;

[0154] First diffuse light-diffusing plate 9: Thickness 3mm;

[0155] Fog Chamber 10: Internal dimensions are ;

[0156] Second diffuse light-diffusing plate 11: 2mm thick;

[0157] Standard color chart 12: 24-color standard color chart;

[0158] Fan assembly 13: 2 low-speed axial fans;

[0159] Temperature and humidity sensor 14: Temperature accuracy , humidity accuracy ;

[0160] Fog controller 15 + fog generator 16: ultrasonic atomization method, medium is deionized water;

[0161] Fiber optic coupler 17 + fiber optic spectrometer 18: wavelength range 400–780 nm, resolution 1.5 nm;

[0162] Data control unit 19: host computer control software, which realizes synchronous triggering of atomization, image acquisition and spectrum acquisition.

[0163] 2.2 Initial Experimental Conditions

[0164] Before the experiment, clean and dry the fog chamber, and control the laboratory ambient temperature at [temperature range missing]. Relative humidity controlled at The industrial camera 5 was manually set to a fixed exposure time of 8ms, a fixed gain of 0dB, and automatic white balance adjustment was disabled. The fiber optic spectrometer 18 had an integration time of 20ms. The image sampling frequency was set to 2fps, and the spectral sampling frequency was set to 2Hz. The standard light source 8 was preheated for 15 minutes before the experiment began.

[0165] 3. Experimental Procedure

[0166] Step 1: Baseline Acquisition

[0167] In a fog-free state, the standard light source 8 is turned on, and the baseline image of the standard color chart 12 is acquired by the industrial camera 5. The fog-free transmission reference spectrum is acquired by the fiber optic spectrometer 18. And record the dark noise spectrum. .

[0168] Step 2: Continuous Fogging

[0169] Start the fog generator 16 and continuously fill the fog chamber 10 with deionized water as the medium for a total filling time of 65 seconds. The fog is divided into three stages: light fog (0-15 seconds), medium fog (15-40 seconds), and dense fog (40-65 seconds).

[0170] Step 3: Synchronous Data Acquisition

[0171] The data control unit 19 simultaneously triggers the industrial camera 5 and the fiber optic spectrometer 18 to perform synchronous data acquisition. Throughout the continuous change of fog concentration, the following are recorded in real time: transmission spectra at different time points; images from the standard color chart 12; and temperature, humidity, and fogging status.

[0172] Step 4: Data Processing

[0173] The overall color transmittance is calculated based on the real-time acquired spectral data. :

[0174] ;

[0175] in: The intensity of the transmitted spectrum at the current moment; The intensity of the transmission spectrum at the fog-free baseline; The intensity of dark noise spectrum; , They are 400nm and 780nm respectively.

[0176] Then, ROI extraction was performed on the standard color chart image 12, and the RGB data was converted to the CIELab space to obtain the brightness values ​​of each color patch. chromaticity coordinates and And calculate the overall chromaticity amplitude:

[0177] ;

[0178] 4. Experimental Results

[0179] 4.1 Image appearance results

[0180] like Figure 2 As shown, during the fogging process, the imaging state of standard color chart 12 gradually changes over time:

[0181] In the fog-free and light fog stages, the color chart boundaries are clear and the color blocks are distinct;

[0182] During the medium fog stage, the contrast between color blocks decreases significantly, and the color difference between warm and cool color blocks narrows.

[0183] During periods of heavy fog, the edges of the color chart become blurred, and some low-saturation color blocks are difficult to distinguish.

[0184] In the terminated state, the image cannot recognize the preset color block information.

[0185] The results show that the device of the present invention can stably reproduce the continuous imaging degradation process from fog-free to foggy.

[0186] 4.2 Transmittance variation data over time

[0187] Table 1 presents the comprehensive color transmittance measurement results at typical time points during the experiment.

[0188] Table 1. Experimental data of comprehensive color transmittance at different time points.

[0189]

[0190] As can be seen from Table 1, transmittance The fog concentration decreases continuously as the fogging time increases, indicating that the device of the present invention can achieve stable adjustment and continuous coverage of fog concentration. Figure 3 (a) can show the overall attenuation trend of the original transmission spectrum. Figure 3 (b) can be used to show the process of the overall color transmittance decreasing monotonically over time.

[0191] 4.3 Data on the lightness and chromaticity variations of typical color patches on the standard color chart

[0192] In this example, four typical color patches are selected from the 24-color standard color chart 12 for analysis: red patch R; green patch G; blue patch B; and neutral gray patch N.

[0193] Table 2 shows the lightness values ​​of these four color patches under different transmittance levels. Changes.

[0194] Table 2. Brightness values ​​of typical color patches under different transmittances.

[0195]

[0196] Table 3 shows the comprehensive chromaticity amplitude of the above typical color blocks. The result of the change.

[0197] Table 3. Comprehensive chromaticity amplitude of typical color patches under different transmittances.

[0198]

[0199] As can be seen from Tables 2 and 3:

[0200] As transmittance decreases, the red, green, and blue high-chroma color patches... and All continued to decline;

[0201] The overall chromaticity amplitude of neutral gray blocks changes little, but the decrease in brightness is equally significant;

[0202] The overall chroma attenuation of high-saturation color blocks was significantly higher than that of neutral gray blocks, indicating that foggy environments not only cause brightness attenuation but also reduce color saturation.

[0203] 4.4 Fitting results of lightness and transmittance, and of comprehensive chromaticity and transmittance

[0204] To demonstrate that this invention can establish a quantitative relationship between fog concentration and image brightness and chromaticity, the overall color transmittance was analyzed. With comprehensive chromaticity amplitude Brightness value Perform a fitting analysis.

[0205] Taking the red patch R as an example, the following fitting relationship is obtained:

[0206] ;

[0207] The coefficient of determination for the fit is:

[0208] ;

[0209] Taking the brightness of neutral gray block N as an example, the following fitting relationship is obtained:

[0210] ;

[0211] The coefficient of determination for the fit is:

[0212] ;

[0213] The overall data of the 24 color blocks were then statistically analyzed, and the average goodness of fit of the combined chromaticity and brightness to the transmittance is shown in Table 4.

[0214] Table 4. Statistical Fitting Results of the Full-Color Card

[0215]

[0216] The above results demonstrate that the device of the present invention can stably obtain synchronous data during continuous fog concentration changes, and can further establish a quantitative mapping relationship between fog concentration and image color rendering parameters. Figure 4(a) and Figure 4 In (b), the fitting trends of lightness and overall chromaticity as a function of transmittance can be represented respectively.

[0217] (II) Application Example 2: Repeatability Verification Experiment

[0218] 1. Experimental Objective

[0219] To verify the experimental repeatability of the device of the present invention, three independent repeated experiments were conducted under the same conditions to compare the consistency of key indicators.

[0220] 2. Repeatability indicators

[0221] Select the following three indicators:

[0222] Terminal state transmittance ;

[0223] The red block is The comprehensive chromaticity amplitude at that time ;

[0224] neutral gray blocks in Brightness value at time .

[0225] 3. Experimental Results

[0226] Table 5. Consistency results of three repeated experiments

[0227]

[0228] As shown in Table 5, the relative standard deviations of the key indicators in the three repeated experiments were all less than 3%, indicating that the device of the present invention has good experimental repeatability and data stability. This proves that, compared with the scheme that relies on a natural fog environment, the present invention can significantly improve the controllability of experimental conditions and the consistency of test results.

[0229] (III) Application Example 3: Comparative Experiment with Asynchronous Acquisition Method

[0230] 1. Purpose of comparison

[0231] To demonstrate the effectiveness of this synchronous acquisition technology, the following comparative scheme was set up under the same device conditions:

[0232] In this invention, the industrial camera 5 and the fiber optic spectrometer 18 are synchronously triggered by the data control unit 19.

[0233] Comparative approach: First acquire the image, then acquire the spectrum after a 3-second delay.

[0234] 2. Comparison Indicators

[0235] Select the average coefficient of determination of the fit between the overall chromaticity and transmittance. As an evaluation indicator.

[0236] 3. Comparison Results

[0237] Table 6 Comparison of Fitting Results Between Synchronous and Asynchronous Acquisition

[0238]

[0239] As shown in Table 6, when the fog concentration changes continuously, asynchronous acquisition results in a significant deterioration in the mapping relationship between the overall chromaticity or brightness and transmittance because the fog state corresponding to the image and the spectrum is not completely consistent. However, the present invention can significantly improve the consistency of data from different modes through synchronous control, thereby improving the fitting accuracy of the mapping model.

[0240] This indicates that the data control unit 19 of the present invention performs unified time-series control on fog generation, image acquisition and spectral acquisition, which can effectively ensure that data of different modes are acquired under the same fog condition, and is an important technical means to achieve high-precision quantitative analysis.

[0241] (iv) Proof of technical effectiveness

[0242] Based on the above application examples and experimental data, it can be proven that the present invention has at least the following technical effects:

[0243] 1. Capable of continuously simulating different fog concentration conditions.

[0244] As can be seen from Table 1, the overall color transmittance can continuously decrease from 1.000 to about 0.152, indicating that the present invention can stably achieve a continuous transition from no fog to dense fog.

[0245] 2. Capable of simultaneously acquiring physical transmission information and imaging color information.

[0246] This invention acquires transmission spectrum data and standard color chart image data simultaneously under the same time, fog field, and lighting conditions, thereby avoiding the state mismatch problem caused by asynchronous acquisition.

[0247] 3. Able to establish a quantitative mapping relationship between fog concentration and image chroma and brightness.

[0248] As shown in Table 4, the average goodness of fit of the overall chromaticity and lightness relative to transmittance of the full-color card reached 0.978 and 0.972, respectively, indicating that the present invention can effectively establish a stable quantitative relationship model.

[0249] 4. It has good experimental repeatability.

[0250] Table 5 shows that the relative standard deviations of the key indicators are all less than 3%, proving that the device of the present invention has good repeatability and comparability.

[0251] 5. Suitable for image dehazing algorithms and visual enhancement model validation.

[0252] Figure 2 The continuously degraded image shown Figure 3 The transmittance variation curve shown and Figure 4 The mapping curve shown can serve as a standard source of experimental data for the development of dehazing algorithms, the verification of color restoration models, and the study of atmospheric scattering visual mechanisms.

[0253] In summary, the experimental apparatus and method for analyzing imaging characteristics in foggy environments described in this invention can stably obtain transmission spectra and standard color chart imaging data under controlled experimental conditions at different fog concentrations. Experimental results show that transmittance continuously decreases with increasing fog concentration, and the lightness values ​​and overall chromaticity amplitudes of each color patch on the standard color chart exhibit a regular decay as transmittance decreases. A quantitative mapping relationship with high fitting degree can be established through an exponential model. Furthermore, the relative standard deviation of key indicators in repeated experiments is less than 3%, indicating that this invention has good experimental repeatability and data stability. Therefore, this invention provides a reliable experimental platform and data foundation for studying imaging degradation patterns in foggy environments and verifying image dehazing algorithms.

[0254] The foregoing description of embodiments of the present invention, through which those skilled in the art are able to implement or use the present invention, will be readily apparent to those skilled in the art. Various modifications to these embodiments will be readily apparent to those skilled in the art. The general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the present invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novelty disclosed herein.

Claims

1. An experimental apparatus for analyzing the imaging characteristics of foggy environments, characterized in that, It includes a camera shooting and light source subsystem, a fog environment generation subsystem, a fog generation and concentration control subsystem, a transmitted light receiving subsystem, and a data control unit; The fog environment generation subsystem includes a fog chamber, a camera real-time shooting and light source subsystem, and a transmitted light receiving subsystem, which are respectively set on both sides of the fog chamber. The fog generation and concentration control subsystem is connected to the fog chamber. The camera shooting and light source subsystem includes an industrial camera, a zoom lens, a filter, a standard light source, and a first diffuse light distribution plate. The industrial camera, zoom lens, and filter are connected in sequence. The standard light source is set towards the fog chamber, and the first diffuse light distribution plate is set on the light output path of the standard light source. The fog environment generation subsystem also includes a second diffuse light equalization plate set on the outer wall of the fog chamber near the camera shooting and light source subsystem, a standard color card set on the inner wall of the fog chamber near the transmission light receiving subsystem, a fan group set at the bottom of the fog chamber, and a temperature and humidity sensor set on the inner wall of the fog chamber. The standard color card and the transmission measurement main optical path are staggered. The transmitted light receiving subsystem includes an optical fiber coupler and an optical fiber spectrometer. The optical fiber coupler is connected to the optical fiber spectrometer, and the receiving end of the optical fiber coupler is aligned with the direction of the standard light source. The system comprises a standard light source, a first diffuse light distribution plate, a second diffuse light distribution plate, a fog chamber, and an optical fiber coupler, which together form the transmission measurement optical path. An industrial camera forms an imaging optical path for the standard color card via a zoom lens and a filter. The data control unit is electrically connected to the fog generation and concentration control subsystem, the industrial camera, and the optical fiber spectrometer, respectively, and is used to synchronously acquire transmission spectral data and standard color card color image data under the same fog condition during continuous changes in fog concentration.

2. The experimental apparatus according to claim 1, characterized in that, After the industrial camera, zoom lens, and filter are connected, their focal plane is set on the standard color card inside the fog chamber.

3. The experimental apparatus according to claim 1, characterized in that, The data control unit is used to achieve time-synchronized control of fog generation, image acquisition, and spectral acquisition.

4. The experimental apparatus according to claim 1, characterized in that, The standard color card is fixed to the inner wall of the fog chamber in the area near the transmitted light receiving subsystem, and is offset in a direction perpendicular to the main optical path of the transmission measurement.

5. The experimental apparatus according to claim 1, characterized in that, The fan assembly is located at the bottom of the fog chamber to promote the uniform diffusion of fog inside the chamber and to assist in emptying the fog after the experiment.

6. The experimental apparatus according to claim 1, characterized in that, The standard light source is a standard white light source. The first diffuse light homogenizing plate and the second diffuse light homogenizing plate are used to reduce illumination non-uniformity and improve the consistency between transmission measurement and color imaging.

7. A method for analyzing imaging characteristics in foggy environments, characterized in that, The experimental apparatus according to any one of claims 1 to 6 comprises the following steps: S1. Prepare the experimental environment: Clean the inside of the fog chamber and adjust the temperature and humidity inside the fog chamber; test and calibrate the instruments in the camera shooting system, the light source subsystem, and the transmission light receiving subsystem, and adjust the transmission measurement optical path and the imaging optical path. S2. Prepare mist medium: Set the target medium concentration of the mist generation and concentration control subsystem, and add the prepared medium solution to the mist generation and concentration control subsystem. S3. Synchronous Data Acquisition: Turn on the standard light source and data control unit, start the fog generation and concentration control subsystem to fill the fog chamber with fog medium, and simultaneously start the industrial camera and fiber optic spectrometer to synchronously record the transmission spectrum data and standard color card color image data under the same fog condition. S4. End the experiment: Turn off the standard light source and data control unit, and turn on the ventilation device of the fog generation and concentration control subsystem and fog chamber for exhaust.

8. The method according to claim 7, characterized in that, In step S3, the fog medium is continuously filled according to the preset concentration change curve, so that the collection process covers the continuous state from no fog to dense fog. And / or, in step S3, the data control unit calculates the transmittance at different wavelengths based on the spectral data collected by the fiber optic spectrometer, and calculates the chromaticity coordinates and lightness values ​​of each color patch based on the standard color chart image collected by the industrial camera; And / or, the acquisition termination condition of step S3 is: the transmission spectrum in the fog chamber tends to stabilize and the standard color card image acquired by the industrial camera cannot identify the preset color block information.

9. The method according to claim 8, characterized in that, The data control unit establishes a quantitative mapping relationship between fog concentration and chromaticity and brightness based on the transmittance, chromaticity coordinates and brightness values ​​under different fog conditions.

10. The method according to claim 8, characterized in that, The chromaticity coordinates and lightness values ​​are represented using CIELab color space parameters.

Images