Method for calibrating gas concentration information and detecting gas concentration and infrared imaging equipment

Abstract

The invention provides a method for calibrating gas concentration information, a method for detecting gas concentration and infrared imaging equipment, and the method comprises the following steps: in a calibration environment, shooting a calibration environment without gas by using the infrared imaging equipment to obtain a first infrared image, and shooting a calibration environment filled with target gas with set concentration to obtain a second infrared image; radiation energy difference parameters are obtained through calculation of the first infrared image and the second infrared image, the leakage concentration of the target gas in the calibration environment is changed, and the radiation energy difference parameters corresponding to the multiple set concentrations are obtained through processing. According to the radiation energy difference parameters corresponding to the multiple set concentrations, the mapping relation between the calibration parameters of the target gas and the gas concentration is calibrated, and the calibration parameters are related to the radiation energy difference parameters. The gas concentration can be conveniently and accurately detected by using the mapping relation between the calibration parameters of the target gas and the gas concentration.

Description

Technical Field

[0001] The present application relates to the technical fields of gas detection and infrared imaging devices, and particularly to a method for calibrating gas concentration information and detecting gas concentration, and an infrared imaging device. Background Art

[0002] With the development of social industry, there are toxic and harmful gases in many industrial production processes. These gases are flammable and explosive, and extremely prone to major safety accidents. When toxic and harmful gases are exposed to the atmosphere, they have serious adverse effects on human health, quality of life and social industrial production activities. Therefore, effective detection and early warning of gas leakage are of great significance for protecting the safety of life, property and the atmospheric environment.

[0003] At present, gas infrared imaging detection technology has been regarded as a powerful tool for gas leakage detection because this method combines rapid measurement, high sensitivity and the ability of remote large-range measurement. However, the research on the quantification of emission concentration by infrared imaging detection is still relatively limited. At present, the research on gas concentration by gas infrared imaging mostly focuses on the concentration detection limit, and it is difficult to achieve accurate quantitative detection of concentration. Summary of the Invention

[0004] To solve the existing technical problems, the present application provides a method for calibrating gas concentration information and detecting gas concentration, and an infrared imaging device for accurately quantitatively detecting gas concentration.

[0005] In the first aspect, a method for calibrating gas concentration information based on an infrared imaging device is provided, and the method includes:

[0006] Taking a first infrared image of a calibration environment without filling gas through an infrared imaging device, and taking a second infrared image of the calibration environment filled with a target gas with a set concentration through the infrared imaging device;

[0007] Calculating a radiation energy difference parameter at the set concentration according to the gray values of the first infrared image and the second infrared image; the radiation energy difference parameter represents the difference between the radiation energy with the target gas and the radiation energy without the target gas; obtaining the radiation energy difference parameters corresponding to multiple set concentrations obtained after changing the set concentration of the target gas in the calibration environment;

[0008] Determining the mapping relationship between the calibration parameter of the target gas and the gas concentration according to the radiation energy difference parameters corresponding to multiple set concentrations; the calibration parameter is related to the radiation energy difference parameter.

[0009] In the second aspect, a method for detecting gas concentration based on an infrared imaging device is provided, and the method includes:

[0010] Take a picture of the current detection environment with an infrared imaging device to obtain an infrared image;

[0011] Based on the infrared image, identify the target gas area and the gas-free area of the infrared image;

[0012] Determine the calibration parameters in the current detection environment; the calibration parameters are related to the radiation energy difference parameter; the radiation energy difference parameter is calculated based on the gray values of the target gas area and the gas-free area;

[0013] Based on the pre-calibrated mapping relationship between the calibration parameters of the target gas and the gas concentration, determine the gas concentration of the target gas corresponding to the calibration parameters in the current detection environment.

[0014] In a third aspect, a computer program product is provided, including a computer program, and when the computer program is executed by a processor, it implements the steps of the method for calibrating gas concentration information based on an infrared imaging device in the above embodiments, or the steps of the gas concentration detection method based on an infrared imaging device in the above embodiments.

[0015] In a fourth aspect, a computer program product is provided, and when the computer program is executed by a processor, it implements the steps of the method for calibrating gas concentration information based on an infrared imaging device in the above embodiments, or the steps of the gas concentration detection method based on an infrared imaging device in the above embodiments.

[0016] In a fifth aspect, an infrared imaging device is provided, including: an infrared detector, an optical system, a processor, and a memory connected to the processor. The memory stores a computer program executable by the processor, and when the computer program is executed by the processor, it implements the steps of the method for calibrating gas concentration information based on an infrared imaging device in the above embodiments, or the steps of the gas concentration detection method based on an infrared imaging device in the above embodiments.

[0017] The method for calibrating gas concentration information based on an infrared imaging device provided in the above embodiments obtains a first infrared image by using the infrared imaging device to photograph a calibration environment without gas and a second infrared image by photographing a calibration environment filled with a target gas at a set concentration in the calibration environment. The radiation energy difference parameter can be calculated from the first infrared image and the second infrared image, and the leakage concentration of the target gas in the calibration environment is changed to process and obtain radiation energy difference parameters corresponding to multiple set concentrations. Furthermore, based on the radiation energy difference parameters corresponding to multiple set concentrations, the mapping relationship between the calibration parameter of the target gas and the gas concentration is calibrated, and the calibration parameter is related to the radiation energy difference parameter. This method obtains the radiation energy difference parameters at different concentrations through calibration operations, thereby fitting the mapping relationship between the calibration parameter of the target gas and the gas concentration, enabling the gas concentration to be quantified by the calibration parameter of the target gas to achieve precise gas concentration quantification detection.

[0018] The method for detecting gas concentration based on an infrared imaging device provided in the above embodiments calibrates the mapping relationship between the calibration parameter and the gas concentration in advance. The calibration parameter is related to the radiation energy difference parameter. Furthermore, the infrared imaging device can be used to photograph the current detection environment to obtain an infrared image. After identifying the target gas area and the gas-free area of the infrared image based on the infrared image, the radiation energy difference parameter can be calculated according to the gray values of the target gas area and the gas-free area to obtain the calibration parameter in the current detection environment. Then, using the mapping relationship between the calibration parameter of the target gas and the gas concentration calibrated in advance, the gas concentration of the target gas corresponding to the calibration parameter in the current detection environment is determined. This method can be completed with only an infrared imaging device with a single band and a monocular lens. There is no need to preset the background or the light source during the detection process. It is a single-band, passive detection method that can quantify the gas concentration of the target gas. This method can be detected using an infrared imaging device and is not restricted by the scene and environment.

[0019] The computer program product and the infrared imaging device provided in the above embodiments belong to the same concept as the corresponding embodiments of the method for calibrating gas concentration information based on an infrared imaging device or the method for detecting gas concentration based on an infrared imaging device. Therefore, they have the same technical effects as the corresponding embodiments of the method for calibrating gas concentration information based on an infrared imaging device or the method for detecting gas concentration based on an infrared imaging device, and will not be elaborated here. Description of the Drawings

[0020] Figure 1 It is a schematic diagram of the layer radiation transfer model in an embodiment.

[0021] Figure 2 For Figure 1 The layer radiation transfer model is simplified to a three-layer radiation transfer model.

[0022] Figure 3 It is a flowchart of a method for calibrating gas concentration information based on an infrared imaging device in an embodiment.

[0023] Figure 4 It is a flowchart of a method for calibrating gas concentration information based on an infrared imaging device in another embodiment.

[0024] Figure 5 It is a schematic diagram of a system for calculating the concentration of a reference gas in an embodiment.

[0025] Figure 6 It is a flowchart of a method for calibrating gas concentration information based on an infrared imaging device in another embodiment.

[0026] Figure 7 It is a flowchart of a method for calibrating gas concentration information based on an infrared imaging device in another embodiment.

[0027] Figure 8 It is a flowchart of a method for detecting gas concentration based on an infrared imaging device in an embodiment.

[0028] Figure 9 It is a flowchart of a method for detecting gas concentration based on an infrared imaging device in an embodiment.

[0029] Figure 10 It is a schematic diagram of the components of an infrared imaging device in an embodiment. Detailed implementation manners

[0030] The technical solution of the present invention will be further elaborated in detail below in conjunction with the accompanying drawings of the specification and specific embodiments.

[0031] In order to make the purpose, technical solution and advantages of this application clearer, the following will further describe this application in detail in conjunction with the drawings. The described embodiments should not be regarded as limitations of this application. All other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of this application.

[0032] In the following description, the expression "some embodiments" is involved, which describes a subset of all possible embodiments. It should be noted that "some embodiments" can be the same subset or different subsets of all possible embodiments, and can be combined with each other without conflict.

[0033] In the following description, the terms "first, second, third" only distinguish similar objects and do not represent a specific order for the objects. It can be understood that "first, second, third" can be interchanged with a specific order or sequence when allowed, so that the embodiments of this application described here can be implemented in an order other than that illustrated or described here.

[0034] An infrared imaging device refers to a type of device that can convert the infrared radiation (i.e., thermal radiation) distribution of an object into an image visible to the human eye, including but not limited to infrared thermal imagers, low-light night vision devices, infrared cameras, etc. Based on the infrared imaging device, this application can calibrate the gas concentration information and then detect the gas concentration according to the calibrated gas concentration information.

[0035] The principle of using an infrared imaging device for gas concentration detection is as follows: When light of a certain frequency passes through the gas to be measured, each molecule in the gas to be measured absorbs a photon and can complete the transition from a lower energy level E1 to a higher energy level E2. When different molecules are irradiated, their vibration modes are also different. The vibration forms of molecules can be divided into two categories: stretching vibration and bending vibration. Stretching vibration refers to the vibration in which atoms elongate or shorten along the bond axis, the bond length of the chemical bond changes while the bond angle remains unchanged, and it can be divided into symmetric and asymmetric stretching vibrations; while the vibration in which atoms vibrate perpendicular to the chemical bond and the bond angle of the molecular group changes while the bond length remains unchanged is called bending vibration. The absorption characteristics of molecules for infrared radiation reflect the vibration of atomic groups in the molecules. The absorption frequency, the number of absorption peaks, and the intensity of the infrared spectrum are all related to the molecular structure. Most gas molecules have a fundamental absorption band in the mid-infrared band, which can be used in gas detection and identification systems. When gas molecules absorb the energy of infrared radiation of certain wavelengths, the vibrational-rotational energy levels undergo transitions, the gas dipole moment changes, and the energy of the molecules absorbing photons transitions from the ground state to the excited state. After the energy of these specific wavelengths of radiation is absorbed, the corresponding spectral transmittance decreases, which is manifested as absorption peaks in the gas infrared spectrum. Therefore, gas can be detected by using gas imaging technologies in different bands.

[0036] Passive infrared imaging of gas leakage is based on the infrared absorption spectrum of gas targets in the atmosphere and the background infrared radiation spectrum for detection, without the need to provide an artificial infrared light source. The infrared radiation of gas targets and their backgrounds is affected by the atmosphere and environmental radiation, etc. during the transmission to the detection system, and its mathematical description is very complex. The layer radiation transport model (Layer Model) is a widely accepted and used gas infrared detection radiation transport model at present, which was proposed by Dennis F. Flanigan et al. of the U.S. Army Chemical Research Development and Engineering Center (CRDEC) and applied to passive infrared imaging detection of gas. As Figure 1 shown, this model divides the entire path of radiation from the background to the detection system into a series of parallel layers, and each layer contains the incident radiation from the previous layer and the outgoing radiation transmitted to the next layer.

[0037] The model divides the path from the target or background to the detection system into a series of parallel layers. Each layer includes the incident radiation from the previous layer and the outgoing radiation transmitted from this layer to the next layer. Thus, for a single layer in the model, such as the i-th layer, its outgoing radiation M i has the following expression:

[0038]

[0039] where is the blackbody radiation of the i-th layer at temperature T i ; M i―1 is the outgoing radiation of the previous layer; ε T , ε A and ε I are the emissivities of the target, atmosphere, and interference objects in the i-th layer, respectively; τ T , τ A and τ I are the transmittances of the target, atmosphere, and interference objects in the i-th layer, respectively; ρ i is the scattering of all components in the i-th layer, especially the scattering caused by impurities such as aerosols.

[0040] When the radiation energy passes through the target gas, according to Kirchhoff's radiation law, the absorptivity is equal to the emissivity, and the sum of the absorptivity and the transmittance is 1. Thus, it can be known that the sum of the emissivity and the transmittance is 1. For the gas leakage infrared detection technology, based on the assumption of ignoring the environmental radiation and the interference of impurities such as aerosols in the atmosphere, the layer radiation transfer model can be simplified to the following formula:

[0041]

[0042] Assuming that the gas or atmosphere distribution in each gas target layer or each atmospheric transmission layer is uniform, then, the layer radiation transfer model can be further simplified to a three-layer radiation transfer model. As Figure 2 shown, taking the front and back boundaries of the gas cloud as the demarcation line, the entire radiation transfer process from the background to the detector is divided into three layers, which are the background layer (layer A), the gas layer (layer B), and the atmospheric transmission layer (layer C) from right to left in sequence. The gas target only exists in layer B.

[0043] There are two different transmission paths in the figure, and one of them contains the target gas. Ignoring the reflection effects of the sky or objects, the background spectral radiation can be expressed as Equation (1-3):

[0044] M BG (λ,T BG )=f BG (ε BG (λ),M(λ,T BG )) (1―3)

[0045] In the formula, ε BG (λ) is the spectral emissivity of the background. Define M i_ON to represent the total radiation emitted from each layer of the gas-containing path, and M i_OFF to represent the total radiation emitted from each layer of the gas-free path. The radiation transfer equation for the gas path is as shown in Equation (1-4):

[0046]

[0047] In the formula, τ i represents the atmospheric transmittance of the i-th layer; M gas (λ, T gas ) is the spectral radiation of the gas cloud, which can be represented by the spectral radiation of a blackbody at temperature T gas . τ gas (λ) is the gas spectral transmittance. From the above formula, the transfer equations for the gas path and the gas-free path can be derived as shown in Equation (1-5) (since in actual measurement cases, the distance from the background to the target gas is much smaller than the distance from the detection point to the target, the background layer is ignored, and for ease of viewing, the parameters λ and T are omitted).

[0048] M C_ON = g C_ON (τ C , τ gas , M BG , M gas , M C )

[0049] M C_OFF = g C_OFF (τ C , M BG , M C ) (1―5)

[0050] For the two path cases shown in Equation (1-5), there is a difference in the radiation energy received by the detection system, which is expressed as Equation (1-6):

[0051] ΔM = |M C_ON ― M C_OFF | = |g ΔM (τ C , τ gas , M BG , M gas , M C )| (1―6)

[0052] According to the Beer-Lambert law, since the absorption paths are all known quantities, the gas spectral transmittance can be written as Equation (1-7):

[0053]

[0054] In the formula, the relationship between the gas spectral transmittance and the concentration C can be indirectly reflected by the radiation energy difference value ΔM between the cases with and without gas. Among them, the radiation energy difference ΔM between the paths with and without gas is expressed as the difference value between the radiation energy of the path with the target gas and the radiation energy of the path without gas. In addition, through theoretical reasoning and experiments, the inventors of the present application found that in addition to the above-mentioned radiation energy difference value ΔM between the cases with and without gas, there are also various parameters that have a certain functional relationship with the gas concentration C. The commonality of these parameters is that they are all related to the radiation energy difference between the cases with and without the target gas. The inventors of the present application define the parameters that reflect the radiation energy difference between the cases with and without the target gas as radiation energy difference parameters, and define the parameters that are related to the radiation energy difference parameters and have a certain functional relationship with the gas concentration C as calibration parameters, so as to calibrate the functional relationship between the calibration parameters of the target gas and the gas concentration according to the radiation energy difference parameters of the target gas at different concentrations.

[0055] Based on the above theory, the present application provides a method for calibrating gas concentration information based on an infrared imaging device, as Figure 3 shown, including the following steps:

[0056] Step 302, obtaining a first infrared image by using an infrared imaging device to photograph a calibration environment without gas filled, and obtaining a second infrared image by using the infrared imaging device to photograph the calibration environment filled with a target gas with a set concentration.

[0057] Among them, the first infrared image and the second infrared image can be obtained through the following calibration operation steps:

[0058] 1. Select a suitable background to construct a calibration environment.

[0059] 2. Observe through thermal imager imaging, and use the thermal imager to collect n first infrared images of the calibration environment without gas.

[0060] 3. Prepare a gas cylinder loaded with a leaking target gas, configure a pressure reducing valve, and the pressure reducing valve can control the gas leakage concentration. Place the gas cylinder loaded with the target gas in front of the background, observe through thermal imager imaging, collect n second infrared images of the calibration environment after filling with the target gas, and record the target gas concentration.

[0061] Among them, the absorption or emission band unique to the target gas matches or overlaps with the detection band of the infrared imaging device, so that the target gas can be effectively detected by the infrared imaging device. Generally speaking, the selection of the infrared gas detection band needs to comprehensively consider the infrared absorption characteristics of the gas, the atmospheric window, and the detector band, and select the wavelength according to the infrared radiation energy of the infrared lens, window filter, and detector, so that the infrared radiation energy reaching the detector matches the characteristic absorption wavelength of the gas to be measured.

[0062] Thus, different gas molecules have specific absorption peaks in specific infrared bands. In practical applications, the working band of a non-cooled infrared imaging device needs to be set according to the absorption band of the gas to be detected.

[0063] Taking a non-cooled long-wave infrared detector as an example, the infrared absorption peak wavelength of methane is 7.8 μm, and that of SF6 is 10.55 μm. The transmission band of the detector itself is 8 - 14 μm. Select the filter window and lens according to the infrared absorption characteristics of the gas to be detected within the detector's transmission band. For example, for methane (CH 4 ), an infrared filter with a wavelength range of 7 - 8.5 μm and a long-wave infrared lens covering this band should be selected. For sulfur hexafluoride (SF 6 ), an infrared filter with a wavelength range of 10.5 - 10.7 μm and the corresponding lens should be selected.

[0064] Taking a cooled mid-wave detector as an example, the characteristic absorption band range of methane is 3.25 - 3.4 μm, and a filter window with a wavelength range of 3.2 - 3.5 μm and the corresponding lens should be selected. The characteristic absorption band range of carbon monoxide is 4.5 - 4.7 μm, and a filter window with a wavelength range of 4.3 - 4.9 μm and the corresponding lens should be selected.

[0065] Based on this wavelength selection, the thermal imager can filter out the infrared radiation outside the target gas band, only receive the narrow-band energy near the absorption peak of the target gas, reduce the signal loss of the gas during the infrared radiation energy transmission process, improve the signal-to-noise ratio of the target gas signal, and make the target gas signal have a high contrast and imaging quality in the thermal imager for the operator to identify.

[0066] Step 304: Calculate the radiation energy difference parameter at the set concentration according to the gray values of the first infrared image and the second infrared image.

[0067] According to the principle of infrared imaging, an infrared image is an image formed by an infrared imaging device collecting the radiation of a target in the infrared band. This radiation mainly comes from the thermal radiation of the target. Therefore, the energy of the infrared image actually reflects the thermal radiation intensity of the target. Furthermore, the gray value of the infrared image can represent the radiation energy of the corresponding area. Calculate the radiation energy difference parameter through the gray values of the first infrared image and the second infrared image.

[0068] Among them, the radiation energy difference parameter is used to represent the difference between the radiation energy of the target gas and the radiation energy of the non-target gas. In one example, the radiation energy difference parameter is the difference value between the radiation energy of the target gas and the radiation energy of the non-target gas. In one example, to eliminate interference, a reference gas can also be introduced during calibration, and the radiation energy difference parameter is the ratio of the first radiation energy difference to the second radiation energy difference, where the first radiation energy difference is the radiation energy difference between the reference gas region and the target gas region, and the second radiation energy difference is the radiation energy difference between the reference gas region and when there is no target gas.

[0069] Among them, the radiation energy difference parameter can be calculated based on the average gray value of n first infrared images and the average gray value of n second infrared images.

[0070] Step 306: After obtaining the set concentration of the target gas in the changing calibration environment, process to obtain the radiation energy difference parameters corresponding to various set concentrations.

[0071] Through the above steps 302 to 304, a radiation energy difference parameter under a certain set concentration can be obtained. During calibration, by controlling the pressure reducing valve of the gas cylinder filled with the leaking target gas, the change in the leakage concentration of the target gas can be controlled. The calibration environment after the set concentration of the changing target gas is collected by the infrared imaging device to obtain the second infrared images corresponding to multiple set concentrations, and then, based on the gray values of the second infrared images and the first infrared images corresponding to multiple set concentrations, the radiation energy difference parameters corresponding to various set concentrations are processed.

[0072] Step 308: Determine the mapping relationship between the calibration parameter of the target gas and the gas concentration according to the radiation energy difference parameters corresponding to various set concentrations; the calibration parameter is related to the radiation energy difference parameter.

[0073] Among them, according to the radiation energy difference parameters corresponding to various set concentrations, the theoretical derivation process of determining the mapping relationship between the calibration parameter of the target gas and the gas concentration is shown in Formulas 1-1 to 1-7, which will not be elaborated here.

[0074] According to Formula 1-7, in the formula, the relationship between the gas spectral transmittance and the concentration C can be indirectly reflected by the radiation energy difference value ΔM between the gas path and the non-gas path. In addition, the inventors of the present application found through theoretical reasoning and experiments that in addition to the above-mentioned radiation energy difference value ΔM between the gas path and the non-gas path, there are also various parameters that have a certain functional relationship with the gas concentration C. The commonality of these parameters is that they are all related to the radiation energy difference between the target gas path and the non-target gas path. Based on this, the parameter that reflects the radiation energy difference between the target gas path and the non-target gas path is defined as the radiation energy difference parameter, and the parameter that is related to the radiation energy difference parameter and has a certain functional relationship with the gas concentration C is defined as the calibration parameter. Thus, according to the radiation energy difference parameters of the target gas at different concentrations, the functional relationship between the calibration parameter of the target gas and the gas concentration is calibrated.

[0075] Among them, the calibration parameter is related to the radiation energy difference parameter of the target gas. For example, the energy difference parameter of the target gas can be the energy difference value ΔM of the target gas, or other parameter values that can represent the difference between the radiation energy of the target gas and the radiation energy of the non-target gas, or an intermediate quantity calculated based on the energy difference parameter of the target gas, such as the gas spectral transmittance, etc.

[0076] In one example, the radiation energy difference value ΔM between the gas path and the non-gas path can be used as the calibration parameter, or other values related to the radiation energy difference value ΔM between the gas path and the non-gas path can be used as the calibration parameter to calibrate the relationship between the calibration parameter of the target gas and the gas concentration C. Thus, when applied, the gas concentration c(x) can be calculated according to the calibration parameter of the target gas.

[0077] The above method for calibrating gas concentration information based on an infrared imaging device obtains a first infrared image by using the infrared imaging device to photograph a calibration environment without gas, and a second infrared image by photographing a calibration environment filled with a target gas at a set concentration in the calibration environment. The radiation energy difference parameter can be calculated through the first infrared image and the second infrared image, and the leakage concentration of the target gas in the calibration environment is changed to obtain radiation energy difference parameters corresponding to various set concentrations. Furthermore, according to the radiation energy difference parameters corresponding to various set concentrations, the mapping relationship between the calibration parameter of the target gas and the gas concentration is calibrated, and the calibration parameter is related to the radiation energy difference parameter. This method obtains the radiation energy difference parameters at different concentrations through the calibration operation, thereby fitting the mapping relationship between the calibration parameter of the target gas and the gas concentration, enabling the gas concentration to be quantified through the calibration parameter of the target gas to achieve accurate gas concentration quantification detection.

[0078] Among them, the influence of environmental parameters is ignored in the above calibration process. To improve the calibration accuracy, the present application further calibrates the mapping relationship between the calibration parameters of the target gas and the gas concentration under different environmental parameters. Thus, during application, different environmental parameters can be matched to relatively accurately determine the gas concentration corresponding to the calibration parameters.

[0079] Specifically, according to the radiation energy difference parameters corresponding to multiple set concentrations, the mapping relationship between the calibration parameters of the target gas and the gas concentration is determined, including: obtaining the radiation energy difference parameters corresponding to different set concentrations under multiple sets of environmental parameters; according to the radiation energy difference parameters corresponding to multiple set concentrations under each set of environmental parameters, determining the mapping relationship between the calibration parameters of the target gas and the gas concentration under different environmental parameters.

[0080] Specifically, the difference between this calibration process and the calibration process of the previous embodiment is that in the calibration process of this embodiment, in addition to changing the leakage concentration of the target gas, the calibration environment is also changed. Among them, the change of the calibration environment is reflected by the change of environmental parameters. In one embodiment, the environmental parameters include the background temperature.

[0081] During this calibration process, under a set of environmental parameters, the radiation energy difference parameters corresponding to different set concentrations are collected respectively.

[0082] For example, a specific calibration process under a certain set of environmental parameters includes the following steps:

[0083] 1. Select a suitable background to construct a calibration environment.

[0084] 2. Prepare a surface source blackbody, through which the infrared radiation energy calibration can be carried out in the infrared imaging device's transmission band.

[0085] 3. Through the thermal imager imaging observation, use the thermal imager to collect n first infrared images without gas in the calibration environment.

[0086] 4. Configure a gas chamber loaded with a leaking target gas, with an air inlet and an air outlet set on the gas chamber and equipped with a gas concentration meter to control the leakage concentration of the target gas. Place the gas chamber loaded with the target gas in front of the background, through the thermal imager imaging observation, collect n second infrared images of the calibration environment after filling the target gas, and record the target gas concentration.

[0087] Taking the infrared imaging device as a thermal imager as an example, among them, the gas chamber is selected based on the infrared radiation transmission band of the target gas, and it needs to cover the transmission band of the thermal imager and cover the absorption peak of the target gas. The size is a fixed length and the diameter is smaller than the diameter of the surface source blackbody. Multiple gas chambers are respectively filled with target gases of different concentrations with gradients, such as 0%, 30%, 50%, 70%, 100%.

[0088] The blackbody signals of the thermal imager at different ambient temperatures and different temperatures have been pre-corrected. During signal acquisition, the gas chamber, the surface source blackbody, and the center of the thermal imager are aligned, and the length of the gas chamber is the distance between the thermal imager and the blackbody.

[0089] Furthermore, according to the gray values of the first infrared image and the second infrared image, calculate the radiation energy difference parameter. According to the radiation energy difference parameters corresponding to multiple set concentrations under this environmental parameter, determine the mapping relationship between the calibration parameter of the target gas and the gas concentration under this environmental parameter.

[0090] On this basis, change the environmental parameter, and further repeat the above calibration operation and analysis steps to obtain the mapping relationship between the calibration parameter of the target gas and the gas concentration under different environmental parameters.

[0091] Taking the environmental parameter as the blackbody temperature as an example, at a certain blackbody temperature, change the gas chamber concentration and collect signals, that is, obtain the signals of different gas concentrations at this background temperature. For example, at a blackbody temperature of 10°C, for gas chambers with 0% (no target gas), 30%, 50%, 70%, and 100%, collect the corresponding infrared images and perform analysis to obtain the mapping relationship between the calibration parameter of the target gas and the gas concentration at a blackbody temperature of 10°C.

[0092] Change the blackbody temperature, such as changing the blackbody temperature to 30°C, 50°C, 70°C. At each blackbody temperature, change the gas chamber concentration and analyze the infrared images to obtain the mapping relationship between the calibration parameter of the target gas and the gas concentration at blackbody temperatures of 30°C, 50°C, and 70°C.

[0093] In this embodiment, during the calibration process, by changing the environmental parameter and the gas concentration, the mapping relationship between the calibration parameter of the target gas and the gas concentration under different environmental parameters can be obtained. Thus, during the gas concentration detection process, the environmental parameter and the calibration parameter can be used as variables for calculation to obtain an accurate gas concentration detection result that matches the environmental parameter and the calibration parameter during detection. This method can improve the accuracy of gas concentration information calibration and further improve the accuracy of gas concentration detection.

[0094] In one embodiment, as shown in Formula 1-7, the relationship between the gas spectral transmittance and the concentration C can be indirectly reflected by the relationship between the radiation energy difference ΔM between the paths with and without the target gas and the concentration C. Therefore, the radiation energy difference parameter includes the radiation energy difference value between the paths with and without the target gas. According to the gray values of the first infrared image and the second infrared image, calculate the radiation energy difference parameter at the set concentration, including: obtaining the radiation energy difference value between the paths with and without the target gas at the set concentration according to the difference between the gray values of the second infrared image and the first infrared image. Specifically, the radiation energy difference value between the paths with and without the target gas is the difference between the radiation energy value with the target gas and the radiation energy value without the target gas at a certain set concentration, as shown in Formula 1-7.

[0095] Correspondingly, this embodiment provides a method for calibrating gas concentration information based on an infrared imaging device, as Figure 4 shown, including the following steps:

[0096] Step 402, obtaining a first infrared image by photographing a calibration environment without gas using an infrared imaging device, and obtaining a second infrared image by photographing a calibration environment filled with a target gas at a set concentration using the infrared imaging device.

[0097] Step 404, obtaining the radiation energy difference value of the presence or absence of the target gas at the set concentration according to the difference in gray values between the second infrared image and the first infrared image.

[0098] Step 406, after obtaining the set concentration of the target gas in the changing calibration environment, processing to obtain the radiation energy difference values of the presence or absence of the target gas corresponding to multiple set concentrations.

[0099] Step 408, determining the mapping relationship between the radiation energy difference value of the presence or absence of the target gas and the gas concentration according to the radiation energy difference values of the presence or absence of the target gas corresponding to multiple set concentrations.

[0100] In this embodiment, the radiation energy difference value of the presence or absence of the target gas is used as a calibration parameter. As shown in Formula 1-7, the relationship between the gas spectral transmittance and the gas concentration C can be obtained by indirectly calibrating the relationship between the radiation energy difference value ΔM of the presence or absence of the target gas and the gas concentration C. Based on this, in this embodiment, according to the radiation energy difference values of the presence or absence of the target gas corresponding to multiple set concentrations, the mapping relationship between the radiation energy difference value of the presence or absence of the target gas and the gas concentration is fitted. Among them, specific fitting methods can be implemented in various ways such as the least squares method, interpolation method, or neural network model training.

[0101] In this embodiment, by calibrating the mapping relationship between the radiation energy difference value of the presence or absence of the target gas and the gas concentration, the gas concentration can be quantified based on the radiation energy difference value of the absence of the target gas. And the radiation energy difference value of the absence of the target gas can be calculated from the gray value of the infrared image. Therefore, this method provides a way to facilitate the use of an infrared imaging device to achieve convenient and accurate gas concentration detection.

[0102] In addition to the above method, the inventors of the present application further found during the research process that although Formula 1-7 can be used as the gas concentration inversion formula, there are many uncertain quantities affecting the measurement. In the formula, M C_ON is the radiation energy value of the path with the target gas received by the infrared imaging device, M C_OFFis the radiation energy value of the gas-free path received by the infrared imaging device. These two values ​​can be obtained by measuring the gray value in the image, but the radiation effect of gas and background is still retained in the formula. gas With M BG , and the atmospheric transmittance τ C Factors that are difficult to measure increase the computational difficulty of gas concentration inversion.

[0103] In view of this situation, the present application also provides an implementation method. During calibration, a reference gas of known concentration is placed in the same background. The reference gas is selected to ensure that its infrared absorption spectrum is similar to that of the target gas, so that the thermal imager can detect the target gas and the reference gas at the same time in the measurement band. Figure 5 Shown is a schematic diagram of the system based on the concentration calculation of the reference gas.

[0104] Based on the radiation transmission model of gas detection in the previous article as the theoretical basis, the radiation energy transmission equation of the system is established as follows (1-8):

[0105]

[0106] Where M gas1 ,M gas2 The spectral radiation of the gas cloud itself can be expressed by the blackbody radiation value of the gas itself, assuming that the reference gas has the same temperature as the target gas, that is, M gas1 =M gas2 , thus subtracting the radiation values ​​under the two gas paths in the above formula, and subtracting the radiation values ​​under the reference gas and no gas path to obtain the following formula (1-9):

[0107] M C_ON_gres ―M C_ON_gmea =|f C_ON ―f C_ON_gmea |

[0108] M C_ON_gres ―M C_OFF =|f C_ON_gmea ―f C_OFF | (1-9)

[0109] Comparing the two equations, we can get equation (1-10):

[0110]

[0111] represents the radiation energy difference parameter, f C_ON is the gray value of the reference gas area, f C_ON_gmea is the gray value of the target gas area, f C_OFF is the gray value without gas; τ gresis the spectral transmittance of the reference gas, τ gmea is the spectral transmittance of the target gas.

[0112] In comparison, this method uses the radiation characteristics of the reference gas to eliminate the influence of the atmosphere and the gas's own radiation.

[0113] Based on the above theory, in one embodiment, a second infrared image is obtained by photographing a calibration environment filled with a target gas at a set concentration through an infrared imaging device, including: obtaining a second infrared image by photographing a calibration environment filled with a reference gas at a fixed concentration and a target gas at a set concentration through an infrared imaging device.

[0114] Specifically, the calibration operation in this example includes:

[0115] 1. Select a suitable background and construct a calibration environment.

[0116] 2. Observe through thermal imager imaging and use the thermal imager to collect n first infrared images without gas in the calibration environment.

[0117] 3. Prepare a gas cylinder loaded with the leaking target gas, configure a pressure reducing valve, and the pressure reducing valve can control the gas leakage concentration. Make a gas chamber loaded with the reference gas. The front and back sides of the gas chamber use materials with better mid-infrared transmission effect to reduce radiation loss during transmission, and the surrounding uses materials with poor thermal conductivity to control the temperature in the gas chamber to be constant. An air inlet and an air outlet are provided on the gas chamber and are equipped with a gas concentration meter to control the concentration of the reference gas.

[0118] 4. Fill the reference gas chamber with a fixed concentration of the reference gas, place the gas cylinder loaded with the target gas and the gas chamber loaded with the reference gas in front of the background, observe through thermal imager imaging, collect n second infrared images of the calibration environment after filling with the target gas and the reference gas, and record the target gas concentration.

[0119] 5. Vary the leakage concentration of the loaded target gas, and through the infrared imaging device, collect n second infrared images of the calibration environment after filling with the target gas and a fixed concentration of the reference gas at different leakage concentrations of the target gas, and record the target gas concentration and the concentration of the reference gas.

[0120] Correspondingly, according to the gray values of the first infrared image and the second infrared image, calculate the radiation energy difference parameter, including: calculating the radiation energy difference parameter at the set concentration according to the gray value of the first infrared image, the gray value of the reference gas region in the second infrared image, and the gray value of the target gas region in the second infrared image.

[0121] In this embodiment, by introducing a reference gas during the calibration process, the influence of the atmosphere and the self-radiation of the gas can be eliminated using the radiation characteristics of the reference gas, and then the mapping relationship between the radiation energy difference parameter and the gas concentration can be accurately calibrated.

[0122] Among them, calculating the radiation energy difference parameter at a set concentration according to the gray value of the first infrared image, the gray value of the reference gas region in the second infrared image, and the gray value of the target gas region in the second infrared image includes:

[0123] Obtaining the first radiation energy difference between the reference gas region and the target gas region according to the absolute value of the difference between the gray value of the reference gas region in the second infrared image and the gray value of the target gas region;

[0124] Obtaining the second radiation energy difference between the reference gas region and the absence of the target gas according to the absolute value of the difference between the gray value of the reference gas region in the second infrared image and the gray value of the first infrared image;

[0125] Obtaining the radiation energy difference parameter at the set concentration according to the ratio of the first radiation energy difference and the second radiation energy difference.

[0126] Specifically, in this embodiment, calculating the radiation energy difference parameter is shown in Formula 1-10. According to Formula 1-10, it can be known that the radiation energy difference parameter in this embodiment is related to the spectral transmittance. Combining with 1-7, the spectral transmittance is related to the gas concentration. Based on this, the mapping relationship between the radiation energy difference parameter and the gas concentration can be indirectly calibrated. Compared with the method of calculating the radiation energy difference parameter in 1-7, since the radiation effects of the gas and the background M gas and M BG , as well as the interference of difficult-to-measure factors such as the atmospheric transmittance τ C are retained in the derivation process of this formula. As can be seen from the derivation process of Formula 1-10, by introducing a reference gas into the calibration environment, the first radiation energy difference between the reference gas region and the target gas region is obtained according to the absolute value of the difference between the gray value of the reference gas region in the second infrared image and the gray value of the target gas region; the second radiation energy difference between the reference gas region and the absence of the target gas is obtained according to the absolute value of the difference between the gray value of the reference gas region in the second infrared image and the gray value of the first infrared image. Then, the radiation energy difference parameter is obtained according to the ratio of the first radiation energy difference and the second radiation energy difference. This calculation method of the radiation energy difference parameter uses the radiation energy difference between the reference gas and the target gas, and the radiation energy difference between the reference gas and the absence of the gas, eliminating the influence of the gas self-radiation and the atmospheric radiation on the concentration measurement accuracy in principle, thus eliminating the interference and improving the calculation accuracy of the radiation energy difference parameter.

[0127] In one embodiment, the energy difference parameter with or without the target gas path can be used as a calibration parameter, and according to the radiation energy difference parameters corresponding to multiple set concentrations, the mapping relationship between the energy difference parameter of the target gas and the gas concentration is obtained by fitting.

[0128] Correspondingly, this embodiment provides a method for calibrating gas concentration information based on an infrared imaging device, as Figure 6 shown, including the following steps:

[0129] Step 602, obtaining a first infrared image by photographing a calibration environment without gas through an infrared imaging device, and obtaining a second infrared image by photographing a calibration environment filled with a reference gas with a fixed concentration and a target gas with a set concentration through the infrared imaging device.

[0130] Step 604, obtaining a first radiation energy difference between the reference gas region and the target gas region according to the absolute value of the difference between the gray value of the reference gas region and the gray value of the target gas region in the second infrared image.

[0131] Step 606, obtaining a second radiation energy difference between the reference gas region and the region without the target gas according to the absolute value of the difference between the gray value of the reference gas region in the second infrared image and the gray value of the first infrared image.

[0132] Step 608, obtaining the radiation energy difference parameter at the set concentration according to the ratio of the first radiation energy difference and the second radiation energy difference.

[0133] Step 610, after obtaining the set concentration of the target gas in the changing calibration environment, obtaining the radiation energy difference parameters corresponding to multiple set concentrations obtained by processing.

[0134] Step 612, determining the mapping relationship between the radiation energy difference parameter of the target gas and the gas concentration according to the radiation energy difference parameters corresponding to multiple set concentrations.

[0135] In this embodiment, a reference gas is introduced into the calibration environment. When calculating the radiation energy difference parameter without the target gas, the radiation energy difference between the reference gas and the target gas, as well as the radiation energy difference between the reference gas and when there is no gas, are used to eliminate the influence of the gas's own radiation and atmospheric radiation on the concentration measurement accuracy from the principle, thereby eliminating interference and improving the calculation accuracy of the radiation energy difference parameter. On this basis, the radiation energy difference parameter is used as the calibration parameter, and according to the radiation energy difference parameters corresponding to various set concentrations, the mapping relationship between the radiation energy difference parameter and the gas concentration is obtained by least squares fitting. Thus, in the concentration detection scenario, referring to Formula 1-10, based on the gray value corresponding to the concentration of the fixed reference gas during calibration, the gray value of the target gas region calculated from the infrared image in the detected environment in real time, and the gray value of the gas-free region, the energy difference parameter of the path with or without the target gas in the detected environment is calculated, and then according to the functional relationship between the energy difference parameter of the path with or without the target gas and the gas concentration calibrated, the gas concentration of the target gas in the current detected environment is calculated.

[0136] In another embodiment, the calibration parameter can also be other parameters related to the radiation energy difference parameter. As shown in combination with Formulas 1-10 and 1-7, the radiation energy difference parameter is related to the spectral transmittance, and the gas concentration C is related to the spectral transmittance. Therefore, the spectral transmittance can also be calculated first according to Formula 1-10, and then the mapping relationship between the spectral transmittance and the gas concentration is directly calibrated.

[0137] Specifically, determining the mapping relationship between the calibration parameter of the target gas and the gas concentration according to the radiation energy difference parameters corresponding to various set concentrations includes: obtaining the spectral transmittance of the reference gas with a fixed concentration; calculating the spectral transmittance of the target gas at various set concentrations according to the radiation energy difference parameter and the spectral transmittance of the reference gas with a fixed concentration; fitting the mapping relationship between the spectral transmittance of the target gas and the gas concentration according to the spectral transmittance of the target gas at various set concentrations; the calibration parameter includes the spectral transmittance.

[0138] Among them, during calibration, the concentration of the reference gas is fixed and known, and the spectral transmittance τ of the reference gas can be calculated according to the reference gas absorption coefficient data in the Hitran database gres . And the radiation energy value of the target gas region, the radiation energy value of the reference gas region, and the radiation energy value when there is no gas can be calculated from the gray values of the corresponding regions on the infrared image. Therefore, the spectral transmittance τ of the target gas at the leakage concentration can be calculated using Formula 1-10 gmea .

[0139] Correspondingly, this embodiment provides a method for calibrating gas concentration information based on an infrared imaging device, as Figure 7As shown, it includes the following steps:

[0140] Step 702: Use an infrared imaging device to capture a first infrared image of the calibration environment without filled gas, and use the infrared imaging device to capture a second infrared image of the calibration environment filled with a reference gas at a fixed concentration and a target gas at a set concentration.

[0141] Step 704: Obtain the first radiation energy difference between the reference gas region and the target gas region according to the absolute value of the difference between the gray value of the reference gas region and the gray value of the target gas region in the second infrared image.

[0142] Step 706: Obtain the second radiation energy difference between the reference gas region and the environment without the target gas according to the absolute value of the difference between the gray value of the reference gas region in the second infrared image and the gray value of the first infrared image.

[0143] Step 708: Obtain the radiation energy difference parameter at the set concentration according to the ratio of the first radiation energy difference and the second radiation energy difference.

[0144] Step 710: After obtaining the set concentration of the target gas in the changing calibration environment, process to obtain the radiation energy difference parameters corresponding to multiple set concentrations.

[0145] Step 712: Calculate the radiation energy difference parameters at multiple set concentrations.

[0146] Step 714: Obtain the spectral transmittance of the reference gas at a fixed concentration.

[0147] Step 716: Calculate the spectral transmittance of the target gas at multiple set concentrations according to the radiation energy difference parameter and the spectral transmittance of the reference gas at a fixed concentration.

[0148] Step 718: Determine the mapping relationship between the spectral transmittance of the target gas and the gas concentration according to the spectral transmittance of the target gas at multiple set concentrations.

[0149] In this embodiment, the calibration parameter includes the spectral transmittance. According to the spectral transmittance of the target gas at the set concentration, the mapping relationship between the spectral transmittance of the target gas and the gas concentration is obtained by fitting. Thus, when detecting the gas concentration, the radiation energy difference parameter can be calculated first according to the infrared image, and then according to the spectral transmittance of the reference gas corresponding to the concentration of the reference gas during calibration, combined with Formula 1-10, the spectral transmittance of the target gas is calculated. According to the mapping relationship between the spectral transmittance of the calibrated target gas and the gas concentration, the current gas concentration of the target gas is inversely obtained.

[0150] Through the above method for calibrating gas concentration information based on an infrared imaging device, the mapping relationship between the calibration parameters of the target gas and the gas concentration can be calibrated. Then, during detection, the corresponding calibration parameters can be obtained in real time. Using this mapping relationship, the gas concentration of the target gas can be detected. Based on this, as Figure 8 shown, the present application also provides a method for detecting gas concentration based on an infrared imaging device, including:

[0151] Step 802, capture the current detection environment through an infrared imaging device to obtain an infrared image.

[0152] Among them, the target gas to be detected matches the working band of the infrared imaging device. Taking an infrared thermal imager as an example, the working band of an uncooled infrared thermal imager needs to be set according to the absorption band of the gas to be detected. Different gas molecules have specific absorption peaks in specific infrared bands.

[0153] Taking an uncooled long-wave infrared detector as an example, the infrared absorption peak wavelength of methane is 7.8um, and the infrared absorption peak wavelength of SF6 is 10.55um. The detector's own transmission band is 8-14um. Select a filter window and lens according to the infrared absorption characteristics of the gas to be detected within the detector's transmission band. For example, methane (CH 4 ) should select an infrared filter of 7-8.5um and a long-wave infrared lens covering this band, and sulfur hexafluoride (SF 6 ) should select an infrared filter of 10.5-10.7um and the corresponding lens.

[0154] Taking a cooled mid-wave detector as an example, the characteristic absorption band range of methane is 3.25-3.4um, and a filter window of 3.2-3.5um and the corresponding lens should be selected. The characteristic absorption band range of carbon monoxide is 4.5-4.7um, and a filter window of 4.3-4.9um and the corresponding lens should be selected.

[0155] Based on this wavelength selection, the thermal imager can filter out the infrared radiation outside the target gas band, only receive the narrow-band energy near the absorption peak of the target gas, reduce the signal loss of the gas during the infrared radiation energy transmission process, improve the signal-to-noise ratio of the target gas signal, and make the target gas signal have a higher contrast and imaging quality in the thermal imager for the operator to identify.

[0156] Step 804, according to the infrared image, identify the target gas region and the gas-free region in the infrared image.

[0157] In one embodiment, a processing model for identifying the segmentation of the gas region in an infrared image can be pre-trained, and this model can achieve gas detection and gas region segmentation. In one embodiment, an initial network model can be created based on YOLO V5, which is suitable for mobile deployment, has a small model size, and fast speed, and a processing model for gas region segmentation can be obtained through training.

[0158] Specifically, a large number of visible gas-containing image test sets are collected through an infrared thermal imager, including different flow rates (high-flow gas plumes, low-flow gas plumes), different backgrounds (pure backgrounds, complex backgrounds, etc.); the gas regions in the images to be trained are labeled to obtain the gas detection boxes of the labeled images; the labeled image pairs and the initial network model are used for training, and a gas detection model is obtained with the SiLU function as the activation function. Different background temperatures are pre-classified, and corresponding thresholds are set according to the model output results to make the confidence of gas detection have an adaptive characteristic.

[0159] Using the detected gas region, the gas region and the background region are separated. By extracting the feature map of the AI model, the contribution of each region in the entire frame of data to the detection result, that is, the probability of the gas, can be obtained. The region where the gas probability is greater than the confidence of the adaptive threshold is determined as the gas region, the edge of the gas region is extracted, the dilation factor is set, and the dilated region is used as the reference background, and the reference background is used as the reference background signal in the concentration calculation.

[0160] Step 806, determine the calibration parameters in the current detection environment; the calibration parameters are related to the radiation energy difference parameter; the radiation energy difference parameter is calculated based on the gray values of the target gas region and the gas-free region.

[0161] In some embodiments, the calibration parameter is the radiation energy difference parameter. In this embodiment, the radiation energy difference parameter, that is, the calibration parameter, is calculated based on the gray values of the target gas region and the gas-free region.

[0162] In some embodiments, the calibration parameter is other parameters related to the radiation energy difference parameter. First, the radiation energy difference parameter can be calculated based on the gray values of the target gas region and the gas-free region, and then the calibration parameter can be calculated based on the radiation energy difference parameter.

[0163] It can be understood that the calibration parameters calculated in the detection environment during gas concentration detection should be consistent with the calibration parameters during calibration of gas concentration information. For example, if the calibration parameter during calibration of gas concentration information is the radiation energy difference parameter, then the calibration parameter calculated in the detection environment during gas concentration detection is also the radiation energy difference parameter. If the calibration parameter during calibration of gas concentration information is the spectral transmittance, then the calibration parameter calculated in the detection environment during gas concentration detection is also the spectral transmittance.

[0164] Step 808: Determine the gas concentration of the target gas corresponding to the calibration parameter in the current detection environment according to the mapping relationship between the calibration parameter of the target gas and the gas concentration calibrated in advance.

[0165] Among them, the mapping relationship between the calibration parameter of the target gas and the gas concentration is obtained by using the method for calibrating gas concentration information based on an infrared imaging device in this application. On this basis, according to this mapping relationship and the calibration parameter in the current detection environment obtained by real-time detection of the infrared image, the gas concentration of the target gas can be inversely calculated.

[0166] The above method for detecting gas concentration based on an infrared imaging device calibrates the mapping relationship between the calibration parameter and the gas concentration in advance. The calibration parameter is related to the radiation energy difference parameter. Furthermore, the infrared imaging device can be used to capture the current detection environment to obtain an infrared image. After identifying the target gas area and the gas-free area of the infrared image, the radiation energy difference parameter can be calculated based on the gray values of the target gas area and the gas-free area to obtain the calibration parameter in the current detection environment. Then, using the mapping relationship between the calibration parameter of the target gas and the gas concentration calibrated in advance, the gas concentration of the target gas corresponding to the calibration parameter in the current detection environment is determined. This method can be completed with only an infrared imaging device with a single band and a monocular lens. During the detection process, there is no need to preset the background or the light source. It is a single-band, passive, and quantifiable detection method for the gas concentration of the target gas. This method can be detected using an infrared imaging device without being restricted by the scene and the environment.

[0167] Regarding the determination of the calibration parameter in the current detection environment in the above step 806, it should be understood that the calibration parameter determined during the detection process should be the same as the calibration parameter used during the calibration process.

[0168] In this application, the calibration parameter can be the radiation energy difference parameter. The corresponding mapping relationship between the calibration parameter of the target gas calibrated in advance and the gas concentration is: the mapping relationship between the radiation energy difference parameter and the gas concentration. Thus, during gas concentration detection, according to the gray values of the target gas area and the gas-free area of the infrared image, the radiation energy difference parameter in the current detection environment is calculated. Furthermore, according to the mapping relationship, the gas concentration corresponding to the radiation energy difference parameter in the current detection environment can be inversely calculated.

[0169] In one embodiment, the calibration parameter is specifically the radiation energy difference value of the presence or absence of the target gas calculated according to formulas 1-7. The method for determining the calibration parameter in the current detection environment in the corresponding step 806 is: calculating the radiation energy difference value of the presence or absence of the target gas according to the difference between the gray values of the target gas area and the gas-free area, and this radiation energy difference value of the presence or absence of the target gas is the calibration parameter in the current detection environment.

[0170] In one embodiment, the calibration parameter is specifically the radiation energy difference parameter calculated according to Formulas 1-10. The method for step 806 to determine the calibration parameter in the current detection environment is as follows: Calculate the third radiation energy difference between the reference gas region and the target gas region based on the absolute value of the difference between the gray value of the reference gas region and the gray value of the target gas region during calibration; Calculate the fourth radiation energy difference between the reference gas region and the region without the target gas based on the absolute value of the difference between the gray value of the reference gas region and the gray value of the region without gas during calibration; Obtain the radiation energy difference parameter based on the ratio of the third radiation energy difference and the fourth radiation energy difference. This radiation energy difference parameter is the calibration parameter in the current detection environment.

[0171] According to Formula 1-10, it can be seen that the radiation energy difference parameter in this embodiment is related to the spectral transmittance. Combining with 1-7, the spectral transmittance is related to the gas concentration. Based on this, the mapping relationship between the radiation energy difference parameter and the gas concentration can be indirectly calibrated. Furthermore, when detecting the gas concentration, calculate the radiation energy difference parameter based on the gray values of the reference gas region, the target gas region, and the region without gas on the infrared image during calibration.

[0172] In this embodiment, by using the radiation characteristics of the reference gas during calibration to eliminate the influence of the atmosphere and the self-radiation of the gas, the accuracy of calculating the radiation energy difference parameter is improved.

[0173] In one embodiment, the calibration parameter includes the spectral transmittance of the target gas related to the radiation energy difference parameter. As shown in combination with Formulas 1-10 and 1-7, the radiation energy difference parameter is related to the spectral transmittance, and the gas concentration C is related to the spectral transmittance. Therefore, the spectral transmittance can also be calculated first according to Formula 1-10, and then the mapping relationship between the spectral transmittance and the gas concentration can be directly calibrated.

[0174] Determining the calibration parameter in the current detection environment includes: calculating the third radiation energy difference between the reference gas region and the target gas region based on the absolute value of the difference between the gray value of the reference gas region and the gray value of the target gas region during calibration; calculating the fourth radiation energy difference between the reference gas region and the region without the target gas based on the absolute value of the difference between the gray value of the reference gas region and the gray value of the region without gas during calibration; obtaining the radiation energy difference parameter based on the ratio of the third radiation energy difference and the fourth radiation energy difference; calculating the calibration parameter in the current detection environment based on the spectral transmittance corresponding to the reference gas with a fixed concentration during calibration and the radiation energy difference parameter.

[0175] In this embodiment, according to 1-10, during gas concentration detection, based on the gray values of the reference gas region and the target gas region on the infrared image, and the gray value of the gas-free region, a radiation energy difference parameter is calculated. Then, according to the spectral transmittance corresponding to the reference gas with a fixed concentration during calibration and the radiation energy difference parameter, the spectral transmittance of the target gas in the current detection environment is calculated. Furthermore, using the pre-calibrated mapping relationship between the spectral transmittance and gas concentration of the target gas, the gas concentration corresponding to the spectral transmittance of the target gas in the current detection environment is calculated.

[0176] In another embodiment, based on the pre-calibrated mapping relationship between the calibration parameters of the target gas and the gas concentration under different environmental parameters, a method for detecting gas concentration based on an infrared imaging device is further provided, as Figure 9 shown, including:

[0177] Step 902, capture the current detection environment by an infrared imaging device to obtain an infrared image.

[0178] Step 904, identify the target gas region and the gas-free region of the infrared image according to the infrared image.

[0179] Step 906, determine the calibration parameters in the current detection environment; the calibration parameters are related to the radiation energy difference parameter; the radiation energy difference parameter is calculated based on the gray values of the target gas region and the gas-free region.

[0180] Step 908, obtain the current environmental parameters in the current detection environment.

[0181] Step 910, obtain the target mapping relationship between the calibration parameters and the gas concentration of the target gas that matches the current environmental parameters.

[0182] Step 912, determine the gas concentration of the target gas corresponding to the calibration parameters in the current detection environment according to the target mapping relationship.

[0183] The method for detecting gas concentration based on an infrared imaging device in this application calculates by taking environmental parameters and calibration parameters as variables, and obtains an accurate gas concentration detection result that matches the environmental parameters and calibration parameters during detection. This method can improve the accuracy of gas concentration information calibration, and thus improve the accuracy of gas concentration detection.

[0184] In another aspect of the embodiments of the present application, there is also provided a computer-readable storage medium, on which a computer program is stored. When the computer program is executed by a processor, it implements the processes of the method for calibrating gas concentration information based on an infrared imaging device or the embodiments of the gas concentration detection method based on an infrared imaging device, and can achieve the same technical effects. To avoid repetition, it will not be elaborated here. Among them, the computer-readable storage medium includes, for example, a read-only memory (ROM), a random access memory (RAM), a magnetic disk, or an optical disc, etc.

[0185] In another aspect of the embodiments of the present application, there is also provided a computer program product, including a computer program. When the computer program is executed by a processor, it implements the processes of the method for calibrating gas concentration information based on an infrared imaging device or the embodiments of the gas concentration detection method based on an infrared imaging device, and can achieve the same technical effects. To avoid repetition, it will not be elaborated here.

[0186] In another aspect of the embodiments of the present application, as Figure 10 shown, there is also provided an infrared imaging device, including: an infrared detector 201, an optical system 202, a processor 203, and a memory connected to the processor. A computer program executable by the processor is stored on the memory. When the computer program is executed by the processor, it implements the processes of the method for calibrating gas concentration information based on an infrared imaging device or the embodiments of the gas concentration detection method based on an infrared imaging device, and can achieve the same technical effects. To avoid repetition, it will not be elaborated here.

[0187] It should be noted that in this document, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, such that a process, method, article or device including a series of elements not only includes those elements but also includes other elements not explicitly listed, or further includes elements inherent to such process, method, article or device. Without further limitations, an element defined by the statement "including one..." does not exclude the existence of additional identical elements in the process, method, article or device including that element.

[0188] Through the description of the above embodiments, those skilled in the art can clearly understand that the above-described example methods can be implemented by means of software plus a necessary general hardware platform. Of course, they can also be implemented by hardware, but in many cases the former is a better implementation. Based on such an understanding, the technical solution of the present invention, in essence, or the part that contributes to the prior art can be embodied in the form of a software product. This computer software product is stored in a storage medium (such as ROM / RAM, magnetic disk, optical disk) and includes several instructions for causing a terminal (which can be a mobile phone, computer, server, or network device, etc.) to execute the methods described in various embodiments of the present invention.

[0189] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any person skilled in the art within the technical scope disclosed in the present application can easily think of changes or substitutions, which should all be covered by the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A method for calibrating gas concentration information based on infrared imaging equipment, characterized in that: The method comprises: The first infrared image is obtained by photographing a calibration environment without gas through an infrared imaging device, and the second infrared image is obtained by photographing a calibration environment filled with a target gas of a set concentration through the infrared imaging device; Calculating the radiation energy difference parameter at the set concentration according to the grayscale values ​​of the first infrared image and the second infrared image; the radiation energy difference parameter represents the difference between the radiation energy with the target gas and the radiation energy without the target gas; After obtaining the set concentration of the target gas in the calibration environment, the radiation energy difference parameters corresponding to the multiple set concentrations obtained by processing are obtained; According to the radiation energy difference parameters corresponding to a plurality of set concentrations, a mapping relationship between the calibration parameters of the target gas and the gas concentration is determined; the calibration parameters are related to the radiation energy difference parameters.

2. The method for calibrating gas concentration information based on infrared imaging equipment according to claim 1, characterized in that: The step of determining the mapping relationship between the calibration parameters of the target gas and the gas concentration according to the radiation energy difference parameters corresponding to the plurality of set concentrations includes: Obtaining the radiation energy difference parameters corresponding to different set concentrations under multiple sets of environmental parameters; According to the radiation energy difference parameters corresponding to the multiple set concentrations under each set of environmental parameters, a mapping relationship between the calibration parameters of the target gas and the gas concentration under different environmental parameters is determined.

3. The method for calibrating gas concentration information based on infrared imaging equipment according to claim 1 or 2, characterized in that: The radiation energy difference parameter includes the radiation energy difference value with or without the target gas; the calibration parameter includes the radiation energy difference value with or without the target gas; The step of calculating the radiation energy difference parameter at the set concentration according to the grayscale values ​​of the first infrared image and the second infrared image includes: The difference in the radiation energy of the target gas at the set concentration is obtained based on the difference in the grayscale values ​​between the second infrared image and the first infrared image.

4. The method for calibrating gas concentration information based on infrared imaging equipment according to claim 1 or 2, characterized in that: The step of photographing a calibration environment filled with a target gas of a set concentration by the infrared imaging device to obtain a second infrared image includes: The infrared imaging device is used to photograph a calibration environment filled with a reference gas of a fixed concentration and a target gas of a set concentration to obtain a second infrared image; Correspondingly, calculating the radiation energy difference parameter at the set concentration according to the grayscale values ​​of the first infrared image and the second infrared image includes: The radiation energy difference parameter at the set concentration is calculated according to the grayscale value of the first infrared image, the grayscale value of the reference gas area in the second infrared image, and the grayscale value of the target gas area in the second infrared image.

5. The method for calibrating gas concentration information based on infrared imaging equipment according to claim 4 is characterized in that: The step of calculating the radiation energy difference parameter at the set concentration according to the grayscale value of the first infrared image, the grayscale value of the reference gas area in the second infrared image, and the grayscale value of the target gas area in the second infrared image includes: Obtaining a first radiation energy difference between the reference gas region and the target gas region according to an absolute value of a difference between a grayscale value of the reference gas region and a grayscale value of the target gas region in the second infrared image; Obtaining a second radiation energy difference between the reference gas area and the target gas-free area according to an absolute value of a difference between a grayscale value of the reference gas area in the second infrared image and a grayscale value of the first infrared image; The radiation energy difference parameter at the set concentration is obtained according to the ratio of the first radiation energy difference to the second radiation energy difference.

6. The method for calibrating gas concentration information based on infrared imaging equipment according to claim 5 is characterized in that: The calibration parameters include the radiation energy difference parameters; The step of determining the mapping relationship between the calibration parameters of the target gas and the gas concentration according to the radiation energy difference parameters corresponding to the plurality of set concentrations includes: According to the radiation energy difference parameters corresponding to a plurality of set concentrations, a mapping relationship between the radiation energy difference parameters and the gas concentration is obtained by fitting.

7. The method for calibrating gas concentration information based on infrared imaging equipment according to claim 5, characterized in that: The step of determining the mapping relationship between the calibration parameters of the target gas and the gas concentration according to the radiation energy difference parameters corresponding to the plurality of set concentrations includes: Acquiring the spectral transmittance of the reference gas at the fixed concentration; Calculating the spectral transmittance of the target gas at a plurality of the set concentrations according to the radiation energy difference parameter and the spectral transmittance of the reference gas at a fixed concentration; According to the spectral transmittance of the target gas under the multiple set concentrations, a mapping relationship between the spectral transmittance of the target gas and the gas concentration is obtained by fitting; the calibration parameter includes the spectral transmittance.

8. The method for calibrating gas concentration information based on infrared imaging equipment according to claim 7, characterized in that: The spectral transmittance of the target gas at various set concentrations is calculated according to the following formula: in, represents the radiation energy difference parameter, f C_ON is the gray value of the reference gas area, f C_ON_gmea is the gray value of the target gas area, f C_OFF is the gray value without gas; τ gres is the spectral transmittance of the reference gas, τ gmea is the spectral transmittance of the target gas.

9. A method for detecting gas concentration based on infrared imaging equipment, characterized in that: The method comprises: The current detection environment is photographed by infrared imaging equipment to obtain an infrared image; According to the infrared image, identifying a target gas region and a gas-free region of the infrared image; Determine calibration parameters under the current detection environment; the calibration parameters are related to the radiation energy difference parameters; the radiation energy difference parameters are calculated based on the grayscale values ​​of the target gas area and the gas-free area; According to the mapping relationship between the calibration parameters of the target gas and the gas concentration that is pre-calibrated, the gas concentration of the target gas corresponding to the calibration parameters under the current detection environment is determined.

10. The method for detecting gas concentration based on infrared imaging equipment according to claim 9, characterized in that: The method further comprises: Obtaining current environmental parameters under the current detection environment; The determining, based on the mapping relationship between the calibration parameters of the target gas and the gas concentration that is pre-calibrated, the gas concentration of the target gas corresponding to the calibration parameters under the current detection environment includes: Acquire a target mapping relationship between the calibration parameters of the target gas and the gas concentration that matches the current environmental parameters; According to the target mapping relationship, the gas concentration of the target gas corresponding to the calibration parameter under the current detection environment is determined.

11. The method for detecting gas concentration based on infrared imaging equipment according to claim 9 or 10, characterized in that: The calibration parameters include the radiation energy difference parameters; The method of calculating the radiation energy difference parameter includes: Calculating the radiation energy difference parameter according to the difference in grayscale values ​​between the target gas region and the gas-free region; or, The third radiation energy difference between the reference gas region and the target gas region is calculated according to the absolute value of the difference between the gray value of the reference gas region and the gray value of the target gas region during calibration; The fourth radiation energy difference between the reference gas region and the target gas-free region is calculated according to the absolute value of the difference between the gray value of the reference gas region during calibration and the gray value of the gas-free region; The radiation energy difference parameter is obtained according to the ratio of the third radiation energy difference to the fourth radiation energy difference.

12. The method for detecting gas concentration based on infrared imaging equipment according to claim 9 or 10, characterized in that: The calibration parameters include the spectral transmittance of the target gas associated with the radiation energy difference parameter; The step of determining the calibration parameters under the current detection environment includes: The third radiation energy difference between the reference gas region and the target gas region is calculated according to the absolute value of the difference between the gray value of the reference gas region and the gray value of the target gas region during calibration; The fourth radiation energy difference between the reference gas region and the target gas-free region is calculated according to the absolute value of the difference between the gray value of the reference gas region during calibration and the gray value of the gas-free region; Obtaining the radiation energy difference parameter according to a ratio of the third radiation energy difference to the fourth radiation energy difference; The calibration parameters under the current detection environment are calculated based on the spectral transmittance corresponding to the reference gas with a fixed concentration during calibration and the radiation energy difference parameter.

13. The method for detecting gas concentration based on infrared imaging equipment according to claim 9 or 10, characterized in that: The mapping relationship between the calibration parameters of the target gas and the gas concentration is obtained by calibrating the gas concentration information based on the infrared imaging device according to any one of claims 1 to 8.

14. A computer program product comprising a computer program, characterized in that When the computer program is executed by a processor, the steps of the method for calibrating gas concentration information based on an infrared imaging device as described in any one of 1 to 8, or the steps of the method for detecting gas concentration based on an infrared imaging device as described in any one of claims 9 to 13 are implemented.

15. An infrared imaging device, characterized in that: include: An infrared detector, an optical system, a processor and a memory connected to the processor, wherein the memory stores a computer program executable by the processor, and when the computer program is executed by the processor, the steps of the method for calibrating gas concentration information based on an infrared imaging device as described in any one of claims 1 to 8, or the steps of the method for detecting gas concentration based on an infrared imaging device as described in any one of claims 9 to 13 are implemented.

Images