Microalgae density measurement method and system based on illumination light source and image analysis

Abstract

The invention discloses a microalgae density measurement method and system based on an illumination light source and image analysis, and the method comprises the steps: an information processing terminal carries out the preprocessing of a collected image, and comprises the operation of unifying the size of the image and separating RGB channels; calculating and optimizing each definition calculation correlation factor, comprehensive definition, RGB channel chromatic aberration, a non-linear change scatter diagram of indexes of comprehensive chromatic aberration under the condition of microalgae solutions with different densities and a non-linear fitting curve of the scatter diagram; a nonlinear fitting curve is optimized, the correlation between scattered points and the fitted curve and the curve smoothness are improved, the advantages of the optimal interval of each algorithm are considered, and local anomalies are reduced; carrying out nonlinear fitting on the optimized scatter diagrams obtained by testing the comprehensive definition under different microalgae density conditions; according to the method, the characteristics of comprehensive chromatic aberration and comprehensive definition are obtained through fitting and modeling, and different characteristics of microalgae solution imaging images with different densities can be accurately distinguished.

Description

Technical Field

[0001] The invention belongs to the technical field of optical testing, and in particular relates to a method and a system for measuring microalgae density based on an illumination light source and image analysis. Background Art

[0002] In the field of microalgae cultivation, in order to accurately and quickly detect the content of microalgae particles, the current traditional detection methods include dry weight method, ultrasonic detection method, counting method and electrode method. The dry weight method is to place a certain volume of suspension in a high-speed centrifuge for solid-liquid centrifugal separation. After several washes, the separated precipitate is centrifuged again, and then the particles after centrifugation are dried at high temperature. Then the dried particles are placed in a constant weight and dry weighing bottle, the mass of the separated particles is weighed, and finally the content of the particles is calculated. The counting method is often used to detect the number of cells, using a cell counter or dyeing with methylene blue. This method requires observation and counting with a microscope, and the sample needs to be diluted multiple times, which may lead to large errors. The working principle of ultrasonic detection method for detecting density is that when the ultrasonic wave passes through the suspension, the particles absorb the sound wave, the ultrasonic energy is attenuated, the amplitude is reduced, and the sound intensity, sound velocity or sound resistance before and after the ultrasonic wave is incident will change. There is a certain relationship between the density and the change of the ultrasonic wave. According to this principle, the density of the suspended particles can be measured. However, such instruments are susceptible to changes in fermentation broth composition, bubbles, temperature changes, and viscosity. The electrode method is a standard electrochemical detection method that uses changes in the permittivity between electrodes to measure the density of particles in the suspension. However, this method is usually used to detect the number of living cells and still has certain limitations for the detection of all types of granular suspended microalgae.

[0003] In addition, the technologies for calculating the density of microalgae mainly include microscopic counting, in vivo fluorescence, spectrophotometry, high-performance liquid chromatography, remote sensing, hyperspectral imaging, microfluidics and microscopic fluorescence counting methods, etc. Among them, the traditional microscopic technical method requires the identification personnel to have rich chemical classification, molecular biology, biochemical analysis level, chemical separation and extraction and instrument use ability, etc., which has high limitations and difficulties in microalgae density testing. The remote sensing method uses remote sensing equipment carried by satellites or drones to monitor the density of microalgae in water bodies on a large scale. It is suitable for rapid monitoring of large areas of water and has obvious advantages in field data collection and large-scale microalgae monitoring. However, the accuracy of the test results is easily affected by weather, cloud thickness, aerosols, water vapor, etc. The microfluidics and microscopic fluorescence technology methods are similar to the hyperspectral imaging method, which can count single microalgae cells quickly and accurately. Most of the above test methods require multiple processes such as microalgae solution sampling, sample preparation, sample testing, and data analysis. Among them, water sample collection may cause contamination to the microalgae culture medium, which makes it difficult to meet the requirements of intelligent density monitoring in large-scale microalgae cultivation.

[0004] Image recognition provides a non-contact, intelligent and environmentally friendly solution for microalgae density monitoring. By analyzing the image features of microalgae solution imaging and establishing a mapping relationship between image features and microalgae density, it can effectively assist in the construction of density recognition algorithms and obtain the density measurement value of algae solutions. At present, image recognition is combined with traditional experimental devices such as biological microscopes, remote sensing equipment, and spectrophotometers (near-field shooting) to further simplify the traditional test process and improve the calculation accuracy. There are few studies on imaging technology and image recognition algorithms for microalgae density calculation under near-field imaging conditions. There is a gap in the research on processing lighting conditions, considering the absorption characteristics of different algae species, and distinguishing properties of different microalgae densities, and the calculation accuracy of microalgae density in different scenarios is not high. Therefore, the method of using a pure color luminous light source with adjustable light field and image recognition collaborative testing under near-field imaging conditions is expected to solve the problems of standardization of microalgae image sample collection, refinement of microalgae feature extraction, and concretization of sample evaluation standards, and help improve the accuracy of microalgae density testing. It is the key to forming a fast, accurate, simple and easy-to-use microalgae density automatic identification system, which plays an important role in large-scale microalgae cultivation, real-time measurement and monitoring. Summary of the invention

[0005] The present invention provides a microalgae density measurement method and system based on illumination light source and image analysis, which can solve the problems of low adjustability and low test accuracy of microalgae density measurement in the prior art by designing an illumination light source and a microalgae density test method and optimizing an image feature extraction algorithm.

[0006] To solve the above problems, the technical solution provided by the present invention is as follows:

[0007] The embodiment of the present invention provides a method for measuring microalgae density based on an illumination light source and image analysis, comprising the following steps:

[0008] Step 1, characterizing the luminous properties of the LED chip (2), such as driving current, light power, and luminous spectrum; characterizing the luminous properties of the light conversion material layer (4), such as light conversion efficiency and luminous spectrum; characterizing the density and algae species properties of the microalgae solution to determine the biological properties of the microalgae solution to be tested;

[0009] Step 2, combining and fixing the LED chip (2) and the reflective cup (3) to form an LED lighting device with a specific lighting angle; fixing the light conversion material layer (4) to the cup mouth of the reflective cup (3) to form an LED lighting device that has excitation light, can realize light conversion, emits light of different colors, and the light intensity of which can be adjusted by current;

[0010] Step 3, using the microalgae solution container to be tested (1) to hold the configured microalgae solution of fixed volume, different algae species and different densities; placing the microalgae solution container to be tested (1) on the lifting platform (6), adjusting the height and horizontal position of the lifting platform (6), the first bracket (7-1) and the second bracket (7-2) to ensure that the center points of the LED chip (2), the reflective cup (3), the light conversion material layer (4), the microalgae solution container to be tested (1) and the camera of the imaging device (5) are aligned and on the same straight line;

[0011] Step 4, adjusting the camera of the imaging device (5) to ensure that the same focal length and the same aperture are maintained when measuring different microalgae solution samples; ensuring that in the same set of experiments, each time the microalgae solution is measured, the microalgae solution container (1) to be measured is placed at the same vertical and horizontal position of the lifting platform (6); the camera of the imaging device (5) is aimed at the halo passing through the microalgae solution to image, collect representative image data, and transmit it back to the information processing terminal (9);

[0012] Step 5, the information processing terminal (9) pre-processes the collected image, including cutting the halo core part, unifying the image size, and separating the RGB channels; on this basis, the brightness, clarity and RGB color difference parameters of the pre-processed image are calculated.

[0013] In an optional embodiment of the present invention, step 5 further includes:

[0014] The selected clarity calculation related factors include: Laplace variance sharpness factor C L , structural similarity index factor C SSIM , local binary clarity factor C LBP , Gaussian blur factor C G , Sobel edge detection factor CSE And the Canny edge detection factor C CE ; After normalization, the above factors are added according to the set weights to obtain the comprehensive clarity C A ; Comprehensive clarity C A The expression is as follows:

[0015] C A =αC L +βC SSIM +γC LBP +δC G +εC SE +ζC CE ; Among them, α, β, γ, δ,

[0016] ε and ζ are the Laplace variance sharpness factors C L , structural similarity index factor C SSIM , local binary clarity factor C LBP , Gaussian blur factor C G , Sobel edge detection factor C SE And the Canny edge detection factor C CE The weight coefficient of

[0017] Calculation method of RGB color difference: extract the RGB value of each pixel from the image, and perform difference calculation with the reference standard color to obtain the color difference of each color channel, and then perform Euclidean distance calculation according to the preset weight of each channel to finally obtain the comprehensive color difference.

[0018] An optional embodiment of the present invention further includes:

[0019] Step 6: Keep the illumination conditions unchanged, replace the same type and different density of microalgae solution for image acquisition, and repeat steps 1 to 5; obtain the relevant factors of each clarity calculation and the comprehensive clarity C A , RGB channel color difference, comprehensive color difference indicators under different density microalgae solution conditions; comprehensive clarity C A The scatter plots obtained under different microalgae density conditions were tested for nonlinear fitting to find the optimal nonlinear fitting function;

[0020] Step 7: Optimize the overall clarity C A Nonlinear fitting curves under different microalgae densities improve the correlation and smoothness of the scatter points and fitted curves;

[0021] Step 8: The optimized comprehensive clarity C obtained in step 7 A The scatter plots obtained under different microalgae density conditions were tested for nonlinear fitting, and the nonlinear fitting curves under different color illumination conditions were compared;

[0022] Step 9, after testing the microalgae solution of known density, use steps 1 to 8 to perform imaging, image processing, image feature extraction and analysis on the microalgae solution of unknown density to obtain the comprehensive clarity C under different luminous color conditions. B The index of the comprehensive clarity C obtained by referring to the microalgae solution sample with known density A The nonlinear fitting curve with the microalgae density was used to obtain the comprehensive clarity C B The corresponding density of the microalgae solution is D B ;

[0023] Step 10, by measuring the comprehensive clarity index of the microalgae sample with known density under different luminous color conditions, and inferring the unknown microalgae density; the accuracy η is D B With D A The absolute value of the difference between A The formula for calculating the microalgae density accuracy η is as follows: η=|D B -D A | / D A , where D A The microalgae density is obtained after testing the microalgae density by the traditional manual counting method;

[0024] Calculate the value of the accuracy η of the microalgae density measurement method test under different luminous color conditions; calculate the value of the accuracy η of the microalgae density measurement method test under different algae species conditions; through the analysis of the accuracy η, further optimize the weights of the clarity-related calculation factors for calculating the comprehensive clarity, and improve the final calculated accuracy η.

[0025] In an optional embodiment of the present invention, step S7 includes: it is necessary to select appropriate clarity calculation related factor calculation weights and RGB color difference calculation weights according to the illumination wavelength to obtain a comprehensive clarity C with a better fitting result. A Nonlinear fitting curves under different microalgae densities; First, the comprehensive clarity C is calculated using the default weights. A , and plot the comprehensive clarity C A and the relationship curve between the density of microalgae; then, analyze the abnormal points in the curve, and try to reduce the weight of the clarity calculation related factors that cause the abnormalities step by step; try to increase the weight of the clarity calculation related factors with good linearity appropriately; in this way, gradually adjust the weights of different clarity calculation related factors, and finally make the comprehensive clarity C A There is a good linear correlation between the density of microalgae and the

[0026] In an optional embodiment of the present invention, step S7 calculates the comprehensive clarity C AWhen optimizing the weights of the relevant factors for different clarity calculations, the default weights of the relevant factors for clarity calculations can be adjusted according to the actual curve shape, or some verified weights can be directly used to optimize the data in accordance with the principle of not expanding local anomalies and giving full play to the advantages of the optimal interval.

[0027] The embodiment of the present invention provides a microalgae density measurement system based on an illumination light source and image analysis, which is used to implement the steps of a microalgae density measurement method based on an illumination light source and image analysis in the above embodiment, characterized in that it comprises a microalgae solution container (1) to be measured, an LED lighting device, an imaging device (5), a lifting platform (6), a first bracket (7-1), a second bracket (7-2), a current source (8) and an information processing terminal (9); the microalgae solution container (1) to be measured is fixed on the top of the lifting platform (6), the first bracket (7-1) and the second bracket (7-2) are arranged on both sides of the lifting platform (6), the LED lighting device is arranged on the top of the first bracket (7-1), and the second bracket (7-2) is arranged on the top of the second bracket (7-1). The imaging device (5) is arranged on the top of the frame (7-2); the LED lighting device and the imaging device (5) are both arranged in alignment with the microalgae solution container (1) to be tested; the LED lighting device is electrically connected to the current source (8); the imaging device (5) is electrically connected to the information processing terminal (9); the information processing terminal (9) is used to obtain information from the imaging device (5) and perform calculation and analysis; wherein the LED lighting device comprises an LED chip (2), a reflective cup (3) and a light conversion material layer (4) covering the light emitting surface of the reflective cup (3); the current source (8) supplies power to the LED chip (2) to control the current of the LED chip (2);

[0028] The container (1) for the microalgae solution to be tested is used to hold microalgae solutions of different types and densities; the LED chip (2) is used as an excitation light source for the light conversion material; the reflective cup (3) is used to collect the light generated by the LED chip (2), guide the light to pass through the light conversion material layer (4), and excite the light conversion material layer (4) to emit light of a specific wavelength; at the same time, the edge size of the reflective cup (3) matches the edge size of the light conversion material layer (4), and is used to fix the light conversion material layer (4); the lifting platform (6) is used to adjust the microalgae solution to be tested. The vertical height of the algae solution container (1) is such that the halo emitted by the light conversion material layer (4) passes through the central position of the microalgae solution container (1); the imaging device (5) is used to record the halo state of the light emitted by the LED chip (2) after passing through the reflective cup (3) and the light conversion material layer (4) and then passing through the microalgae solution container (1) to be measured; before imaging, the positions of the first bracket (7-1) and the second bracket (7-2) can be adjusted to meet the shooting focal length requirements of the imaging device (5) and achieve the best imaging effect.

[0029] In an optional embodiment of the present invention, the light emission band of the LED chip (2) is blue light or ultraviolet light, wherein, when the thickness of the microalgae solution container (1) to be tested is relatively thick, a relatively high-power LED chip can be selected to emit light to ensure that the emitted light has relatively high penetration; when the thickness of the microalgae solution container (1) to be tested is relatively thin, a relatively low-power LED chip can be selected to emit light to ensure that the halo will not be overexposed when imaging the imaging device (5).

[0030] In an optional embodiment of the present invention, the material of the light conversion material layer (4) is any one of the light conversion materials in fluorescent powder, quantum dots, perovskite or organic dyes; the reflective cup (3) is made of aluminum or acrylic material, and its inner wall is a smooth or rough texture structure; the microalgae solution container (1) to be tested is made of transparent acrylic, transparent glass, or transparent quartz material, and the microalgae solution container (1) to be tested is used to store one or more algae from common microalgae such as Navicula, Thalassiosira, Haematococcus pluvialis, and Oocystis.

[0031] In an optional embodiment of the present invention, the imaging device (5) is a camera or a mobile phone, wherein the aperture of the imaging device (5) is adjustable and can be adjusted to the minimum aperture that can just capture the halo at the highest density of the microalgae solution as needed.

[0032] In an optional embodiment of the present invention, the information processing terminal (9) is a desktop computer or a tablet computer, which is used for image processing and analysis; wherein the information processing terminal (9) uses Photoshop, GIMP, Affinity Photo software to perform preliminary processing on videos and images, and to crop the parts of the images with halo characteristics.

[0033] Compared with the prior art, the embodiment of the present invention provides a method and system for measuring microalgae density based on illumination light source and image analysis, which has the following beneficial effects:

[0034] (1) The present invention proposes a microalgae density measurement method and system based on illumination light source and image analysis. The microalgae density measurement method uses light as a medium, is contactless, environmentally friendly, and does not require frequent sampling. The density of the microalgae solution can be monitored at different parts of the microalgae cultivation container only by using a mobile testing device, thereby avoiding the contamination of the microalgae solution caused by frequent sampling.

[0035] (2) The present invention can directly use cheap LED lighting devices as light sources, use common imaging devices such as mobile phones as monitoring tools for microalgae density, and use the imaging image centered on the halo of the microalgae solution as the monitoring object. It has the advantages of being simple and easy to test. The test system is portable and can be widely used in various microalgae density monitoring occasions.

[0036] (3) The present invention assembles the light source required for the microalgae density test by combining a light conversion material layer with a reflective cup and an LED chip. The light source has flexible adjustability in the microalgae density test, and a suitable light source combination can be selected from any assembled LED lighting device to assist in the imaging of the microalgae image. Compared with the traditional LED lighting device with a single luminous spectrum, the present invention is more suitable for studying the imaging mechanism of the microalgae halo image from the perspective of light source-assisted imaging, and is suitable for multiple fields such as scientific research and monitoring.

[0037] (4) The present invention proposes a method for imaging a microalgae solution of known density and extracting image features under the conditions of LED lighting devices with different luminous colors, and further proposes concepts such as comprehensive color difference and comprehensive clarity through fitting and modeling, which can accurately distinguish the different features of the imaging images of the microalgae solution under conditions of different microalgae densities. Compared with the traditional method of directly photographing the microalgae solution to obtain an image, this method solves the problem that the imaging features of the microalgae solution under high-density and low-density conditions are not obvious and the distinction is not high.

[0038] (5) The present invention proposes a new method for evaluating the density of microalgae using the concepts of comprehensive color difference and comprehensive clarity. By calculating and optimizing the parameters of comprehensive color difference and comprehensive clarity, the efficiency of image feature extraction of microalgae solutions under high-density and low-density conditions can be improved, and a nonlinear fitting curve that better matches the experimental results can be obtained, thereby solving the problem of inaccurate calculation of microalgae density.

[0039] (6) The present invention proposes a method for calculating accuracy, which can evaluate the accuracy of calculating the density of microalgae using the method of the present invention compared with the traditional counting method under the conditions of different combinations of light conversion materials and LED chips. The scope of application of the present invention under different test conditions is further clarified through the evaluation of the accuracy.

[0040] (7) The test method of the present invention is simple, easy to operate, low-cost, flexible and adjustable. After a large number of experimental verifications, the calculation of microalgae density has a high test accuracy. Therefore, the present invention has certain commercial value. Whether in the fields of marine sewage detection, microalgae solution culture monitoring, or breakthroughs in key technologies of marine visible light sensing, the present invention can support its technical needs and effectively assist in the realization of the goals of "carbon neutrality and carbon peak". BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments or the prior art, the drawings required for use in the embodiments or the description of the prior art will be introduced below. Obviously, the drawings described below are only some embodiments of the invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0042] Figure 1 A flow chart of a method for measuring microalgae density based on illumination light source and image analysis provided in an embodiment of the present application.

[0043] Figure 2 A schematic diagram of a microalgae density measurement system based on illumination light source and image analysis provided in an embodiment of the present application.

[0044] Figure 3 A schematic diagram of the relationship between the brown algae solution under orange light and the clarity calculation correlation factors provided in the embodiments of the present application.

[0045] Figure 4 Schematic diagram of the brightness change curve of brown algae images of different densities under blue light provided in an embodiment of the present application.

[0046] Figure 5 RGB color difference of green algae pictures of different densities under orange light provided in the embodiments of the present application.

[0047] Figure 6RGB color difference of green algae pictures of different densities under blue light, green light, orange light and red light provided in the embodiments of the present application.

[0048] Figure 7 This is the density calculation accuracy of the brown algae solution provided in the embodiment of the present application under different color light conditions. DETAILED DESCRIPTION

[0049] The technical solutions in the embodiments of the present application will be described clearly and completely below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative work are within the scope of protection of the present application.

[0050] The embodiment of the present invention provides a method and system for measuring the density of microalgae based on illumination light source and image analysis. The present invention realizes different light intensities and luminous colors by preparing and encapsulating luminous light sources, and uses a current source to control the driving current of the luminous light source; under the condition of a certain distance, a camera is used to collect, process and analyze the microalgae halo pictures of different densities under the same focal length condition, and the brightness change characteristics, color difference change characteristics, brightness uniformity characteristics, clarity and other characteristics of the microalgae halo pictures of different densities under the RGB channel are obtained. In addition, the present invention also proposes an accuracy algorithm for calculating the density of microalgae, and calculates and analyzes the accuracy of microalgae density measurement under the conditions of luminous light source and no luminous light source, and compares it with the accuracy of microalgae density calculation obtained by traditional measurement methods such as counting method, and evaluates the feasibility and accuracy of the method; the microalgae density measurement method of the present invention is simple and accurate, which ensures the reliability of microalgae density calculation.

[0051] Specifically, Figure 1 As shown, an embodiment of the present invention provides a method for measuring microalgae density based on an illumination light source and image analysis, comprising the following steps:

[0052] Step 1, characterize the luminous properties of the LED chip 2, such as driving current, light power, and luminous spectrum; characterize the luminous properties of the light conversion material layer 4, such as light conversion efficiency and luminous spectrum; characterize the density and algae species properties of the microalgae solution to determine the biological properties of the microalgae solution to be tested;

[0053] Step 2, combining and fixing the LED chip 2 and the reflective cup 3 to form an LED lighting device with a specific lighting angle; fixing the light conversion material layer 4 to the cup mouth of the reflective cup 3 to form an LED lighting device with excitation light, capable of realizing light conversion, emitting light of different colors, and whose light intensity can be adjusted by current;

[0054] Step 3, using the microalgae solution container 1 to be tested to hold the configured microalgae solution of fixed volume, different algae species and different densities; placing the microalgae solution container 1 to be tested on the lifting platform 6, adjusting the height and horizontal position of the lifting platform 6, the first bracket 7-1 and the second bracket 7-2 to ensure that the center points of the LED chip 2, the reflective cup 3, the light conversion material layer 4, the microalgae solution container 1 to be tested, and the camera of the imaging device 5 are aligned and on the same line;

[0055] Step 4, adjusting the camera of the imaging device 5 to ensure that the same focal length and the same aperture are maintained when measuring different microalgae solution samples; ensuring that in the same set of experiments, each time the microalgae solution is measured, the microalgae solution container 1 to be measured is placed at the same vertical and horizontal position of the lifting platform 6; the camera of the imaging device 5 is aimed at the halo passing through the microalgae solution to image, collect representative image data, and transmit it back to the information processing terminal 9;

[0056] Step 5, the information processing terminal 9 pre-processes the collected image, including cutting the halo core part, unifying the image size, and separating the RGB channels; on this basis, the brightness, clarity and RGB color difference parameters of the pre-processed image are calculated.

[0057] Preferably, step 5 further comprises: the selected clarity calculation related factors include: Laplace variance sharpness factor C L , structural similarity index factor C SSIM , local binary clarity factor C LBP , Gaussian blur factor C G , Sobel edge detection factor C SE And the Canny edge detection factor C CE ; After normalization, the above factors are added according to the set weights to obtain the comprehensive clarity C A ; Comprehensive clarity table C A The expression is as follows:

[0058] C A =αC L +βC SSIM +γC LBP +δC G +εC SE +ζC CE ;

[0059] Among them, α, β, γ, δ, ε, and ζ are the Laplace variance sharpness factors C L , structural similarity index factor C SSIM , local binary clarity factor C LBP , Gaussian blur factor C G , Sobel edge detection factor C SEAnd the Canny edge detection factor C CE The weight coefficient of .

[0060] Calculation method of RGB color difference: extract the RGB value of each pixel from the image, and perform difference calculation with the reference standard color to obtain the color difference of each color channel, and then perform Euclidean distance calculation according to the preset weight of each channel to finally obtain the comprehensive color difference.

[0061] Preferably, a method for measuring microalgae density based on illumination light source and image analysis further comprises:

[0062] Step 6: Keep the illumination conditions unchanged, replace the same type and different density of microalgae solution for image acquisition, and repeat steps 1 to 5; obtain the relevant factors of each clarity calculation and the comprehensive clarity C A , RGB channel color difference, comprehensive color difference indicators under different density microalgae solution conditions; comprehensive clarity C A The scatter plots obtained under different microalgae density conditions were tested for nonlinear fitting to find the optimal nonlinear fitting function;

[0063] Step 7: Optimize the overall clarity C A The nonlinear fitting curve under different microalgae density conditions improves the correlation between the scattered points and the fitted curve and the smoothness of the curve;

[0064] Step 8: The optimized comprehensive clarity C obtained in step 7 A The scatter plots obtained under different microalgae density conditions are subjected to nonlinear fitting, and the nonlinear fitting curves under different color illumination conditions are compared. In the embodiment, the conventional double exponential decay model is mainly used for processing to establish the corresponding relationship between the microalgae density in the solution and the image clarity, thereby realizing the calculation of the microalgae density based on the image clarity. Similarly, the method of step 7 can be used to calculate the clarity correlation factor (Laplace variance sharpness factor C in step 6) L , structural similarity index factor C SSIM , local binary clarity factor C LBP , Gaussian blur factor C G , Sobel edge detection factor C SE And the Canny edge detection factor C CE The fitting curves of indicators such as RGB color difference and comprehensive color difference under different microalgae densities were optimized in the same way.

[0065] Step 9, after testing the microalgae solution of known density, use steps 1 to 8 to perform imaging, image processing, image feature extraction and analysis on the microalgae solution of unknown density to obtain the comprehensive clarity C under different luminous color conditions. BThe index of the comprehensive clarity C obtained by referring to the microalgae solution sample with known density A The nonlinear fitting curve with the microalgae density was used to obtain the comprehensive clarity C B The corresponding density of the microalgae solution is D B ;

[0066] Step 10, by measuring the comprehensive clarity index of the microalgae sample with known density under different luminous color conditions, and inferring the unknown microalgae density; the accuracy η is D B With D A The absolute value of the difference between A The formula for calculating the microalgae density accuracy η is as follows: η=|D B -D A | / D A , where D A The microalgae density is obtained after testing the microalgae density by the traditional manual counting method;

[0067] Calculate the value of the test accuracy η of the microalgae density measurement method under different luminous color conditions; calculate the value of the test accuracy η of the microalgae density measurement method under different algae species conditions; through the analysis of the accuracy η, further optimize the weights of the clarity-related calculation factors for calculating the comprehensive clarity, and improve the final calculated accuracy η.

[0068] Similarly, the calculation formula of the accuracy η can also be used to characterize the correlation factor (Laplace variance sharpness factor C) calculated using clarity. L , structural similarity index factor C SSIM , local binary clarity factor C LBP , Gaussian blur factor C G , Sobel edge detection factor C SE And the Canny edge detection factor C CE The accuracy of calculating the unknown microalgae density by methods such as RGB color difference and comprehensive color difference.

[0069] Preferably, the specific operation of step 7 is as follows: Since the corresponding density intervals of the color difference of each clarity algorithm and each channel characterizing the properties of microalgae are significantly different. For example, Sobel edge detection and Canny edge detection have better performance under the condition that the halo edge is more obvious, while Laplace variance often performs better under the condition that the halo is severely diffused. In addition, due to the different absorption and scattering characteristics of different light sources and luminous spectra, the degree of halo diffusion will be directly affected. Therefore, it is necessary to select appropriate clarity calculation related factor calculation weights and RGB color difference calculation weights in accordance with the illumination wavelength to obtain a comprehensive clarity C with better fitting results. A Nonlinear fitting curves under different microalgae densities. First, the comprehensive clarity C was calculated using the default weights.A , and plot the comprehensive clarity C A Next, analyze the abnormal points in the curve, and try to reduce the weight of the clarity calculation related factors that cause the abnormalities; try to increase the weight of the clarity calculation related factors with good linearity appropriately. In this way, gradually adjust the weights of different clarity calculation related factors, and finally make the comprehensive clarity C A A good linear correlation is formed between the density of microalgae and the density of microalgae. Preferably, the entire optimization process can also be implemented through common optimization algorithms such as gradient descent and differential evolution to improve the adjustment efficiency and automation.

[0070] Step 7 Calculate the comprehensive clarity C A When optimizing the weights of the relevant factors for different clarity calculations, the default weights of the relevant factors for clarity calculations can be adjusted according to the actual curve shape, or some verified weights can be directly used to optimize the data in accordance with the principle of not expanding local anomalies and giving full play to the advantages of the optimal interval.

[0071] like Figure 2 As shown, an embodiment of the present invention also provides a microalgae density measurement system based on an illumination light source and image analysis, which is used to implement the steps of a microalgae density measurement method based on an illumination light source and image analysis in the above embodiment. A microalgae density measurement system based on an illumination light source and image analysis comprises a microalgae solution container 1 to be measured, an LED lighting device, an imaging device 5, a lifting platform 6, a first bracket 7-1, a second bracket 7-2, a current source 8 and an information processing terminal 9. The microalgae solution container 1 to be measured is fixed on the top of the lifting platform 6, and the first bracket 7-1 and the second bracket 7-2 are arranged on both sides of the lifting platform 6. The top of the first bracket 7-1 is provided with an LED lighting device, and the top of the second bracket 7-2 is provided with an imaging device 5. The LED lighting device and the imaging device 5 are both arranged in alignment with the microalgae solution container 1 to be measured. The LED lighting device is electrically connected to the current source 8, and the imaging device 5 is electrically connected to the information processing terminal 9. The information processing terminal 9 is used to obtain information from the imaging device 5 and perform calculations and analyses. The LED lighting device includes an LED chip 2, a reflective cup 3, and a light conversion material layer 4 covering the light emitting surface of the reflective cup 3. The current source 8 supplies power to the LED chip 2 to control the current size of the LED chip 2.

[0072] The container 1 for the microalgae solution to be tested is used to hold microalgae solutions of different types and densities; the LED chip 2 is used as an excitation light source for the light conversion material; the reflective cup 3 is used to collect the light generated by the LED chip 2, guide the light to pass through the light conversion material layer 4, and excite the light conversion material layer 4 to emit light of a specific wavelength; at the same time, the edge size of the reflective cup 3 matches the edge size of the light conversion material layer 4, and is used to fix the light conversion material layer 4; the lifting platform 6 is used to adjust the vertical height so that the halo emitted by the light conversion material layer 4 passes through the central position of the microalgae solution container 1; the imaging device 5 is used to record the halo state of the light emitted by the LED chip 2 after passing through the reflective cup 3 and the light conversion material layer 4 and passing through the microalgae solution container 1; before imaging, the position of the first bracket 7-1 and the second bracket 7-2 can be adjusted to meet the shooting focal length requirements of the imaging device 5 to achieve the best imaging effect.

[0073] The light emission band of the LED chip 2 is a variety of common short-wavelength light for excitation, such as blue light and ultraviolet light. In order to make the parameters such as the light power and light intensity emitted by the LED chip 2 in the illumination light source match the microalgae solution container 1 to be tested, the LED chip 2 can be selected. When the thickness of the microalgae solution container 1 to be tested is relatively thick, a relatively high-power LED chip can be selected to emit light to ensure that the light penetration is relatively high; when the thickness of the microalgae solution container 1 to be tested is relatively thin, a relatively low-power LED chip can be selected to emit light to ensure that the halo will not be overexposed in the imaging device 5.

[0074] In order to make the parameters such as the light power and light intensity emitted by the LED chip 2 in the LED lighting device match those of the microalgae solution container 1 to be tested, the current source 8 that drives the LED chip 2 to emit light can be adjusted: if the thickness of the microalgae solution container 1 to be tested is relatively thick, the driving current of the LED chip 2 can be increased through the current source 8 to obtain a larger power of light to ensure that the light penetration is high; if the thickness of the microalgae solution container 1 to be tested is relatively thin, the driving current of the LED chip 2 can be reduced through the current source 8 to ensure that the halo will not be overexposed at the imaging terminal.

[0075] In order to make the parameters such as the light power and light intensity emitted by the LED chip 2 in the LED lighting device match the microalgae solution container 1 to be tested, the microalgae solution container 1 to be tested can be selected: if the LED chip 2 has a higher light power and a stronger light intensity, a microalgae solution container 1 to be tested with a thicker container thickness can be selected to ensure higher light penetration; if the LED chip 2 has a lower light power and a weaker light intensity, a microalgae solution container 1 to be tested with a thinner container thickness can be selected to ensure that the halo imaging at the imaging terminal will not be unable to penetrate or the edge will not cross the boundary.

[0076] The material of the light conversion material layer 4 is any one of the commonly used light conversion materials such as phosphors, quantum dots, perovskites and organic dyes. Among them, phosphors emit light more stably, but the spectrum is wider; quantum dots and perovskite materials have a single light emission spectrum and can be used to study the imaging effect of monochromatic light; organic dyes can provide light emission of different colors, but the light emission spectrum is not highly symmetrical; the above light conversion materials can be selected according to test needs.

[0077] After the light conversion material layer 4 is determined, the luminous color is any one or more in the visible light range. The luminous color can be regulated and changed according to the synthesis mechanism of the light conversion material layer 4. When the same LED chip 2 and different light conversion materials 4 are used, the overall color of the lighting source can be changed; when different LED chips 2 and different light conversion materials 4 are used, the overall color of the lighting source can also be changed. The light conversion material layer 4 of this embodiment is in the form of a thin sheet, which is convenient for light to pass through the light conversion material; the thickness of the light conversion material layer 4 is usually about 2 to 3 mm, which ensures a certain light transmittance on the one hand, and ensures that the purity of the luminous color passing through the light conversion material is high on the other hand; at the same time, the selection of the light conversion material needs to consider its optical properties such as luminous color, quantum efficiency, luminous power, as well as its conversion rate and related response speed in the light conversion process and other properties related to detection and sensing.

[0078] Among the various light conversion materials used for lighting and display, such as commercial phosphors, organic dyes, perovskites, carbon dots, quantum dots, etc., quantum dot materials with high quantum efficiency, good monochromaticity, stable luminescence and fast modulation rate can be selected; taking cadmium selenide quantum dots as an example, it can produce any required luminescence wavelength in the visible light range under the excitation of blue light or ultraviolet light, and can achieve stable luminescence under high temperature conditions, which meets the requirements of realizing multiple different light conversion wavelengths to test the density of microalgae in this embodiment.

[0079] The use of quantum dots as light conversion materials plays a great supporting role in achieving its effects. Compared with other light conversion materials, the technical advantages of quantum dots include: 1. The luminescence peak of quantum dots is narrow, and the half-peak width ranges from about 20 nanometers to 40 nanometers, which helps to avoid the impact of inconsistent absorption coefficients of different bands in microalgae solutions on the experiment; 2. The internal quantum yield of quantum dots can be as high as 90%, with high luminescence intensity, thereby ensuring the stability of the total luminescence intensity; 3. The response speed of quantum dots is higher than that of ordinary commercial phosphors. Their fluorescence lifetime is usually on the order of 10 nanoseconds, while the fluorescence lifetime of commercial phosphors is as long as microseconds, which limits their response speed in light detection. Therefore, when using quantum dots for testing, the test requirements of rapid response can be met; 4. The luminescent color of quantum dots can be conveniently adjusted by controlling the size of quantum dots, the proportion of elements, etc. Therefore, in the experiment, continuously changing monochromatic light can be used to test the density of microalgae, and this continuously changing test effect cannot be achieved with traditional discrete luminescent peak semiconductor devices such as laser diodes and high-power light-emitting diodes; 5. The luminescent properties of quantum dots are relatively stable in a water-oxygen environment and can withstand high temperatures. They can be used with high-power LEDs and lasers to produce stable light output, thereby supporting the implementation of the experiment; 6. Compared with materials such as perovskites that have high requirements for non-polar environments, their film-forming properties are poor, and the manufacturing process of quantum dot membranes made of silicone can support quantum dots to be made into various flexible shapes to meet the needs of co-packaging with high-power light-emitting diodes in experiments.

[0080] The reflective cup 3 is made of aluminum or acrylic, and its inner wall is a smooth or rough texture structure. The size and thickness of the microalgae solution container 1 to be tested can be selected to meet the test requirements of various different light sources. The microalgae solution container 1 to be tested is made of transparent acrylic, transparent glass, and transparent quartz. Considering the cost and ease of use, a transparent acrylic container is preferred. The microalgae solution container 1 to be tested is used to store one or more algae of common microalgae such as Navicula, Thalassiosira, Haematococcus pluvialis, and Oocystis.

[0081] The imaging device 5 is a camera or a mobile phone, wherein the focal length of the imaging device 5 is adjustable, and the standard for adjustment is that when the microalgae solution to be tested is not placed, the imaging terminal can clearly present the image of the standard light source. The aperture of the imaging device 5 is adjustable, and it is adjusted to the minimum aperture that can just capture the halo of the microalgae solution at the highest density as needed. In other embodiments, the imaging device 5 and the information processing terminal 9 can be integrated into a dedicated embedded device; or they can be a separate part of the system and then connected with a data cable.

[0082] The plane fixing positions of the lifting platform 6, the first bracket 7-1 and the second bracket 7-2 are adjustable; the fixing method can be fixed on the optical breadboard by screws, or fixed on the optical platform. By adjusting the fixing positions of the lifting platform 6, the first bracket 7-1 and the second bracket 7-2, the illumination distance between the light conversion material layer 4 and the microalgae solution container 1 to be tested can be adjusted during the test, and the imaging distance of the imaging device 5 can be adjusted.

[0083] The horizontal heights of the lifting platform 6, the first bracket 7-1, and the second bracket 7-2 are adjustable by using the bracket knob of the lifting platform 6 and adjusting the heights of the support rods of the first bracket 7-1 and the second bracket 7-2; the height can be selected based on the size of the reflective cup 3, the size of the microalgae solution container 1 to be tested, etc.

[0084] The information processing terminal 9 is a desktop computer or tablet computer for image processing and analysis; wherein, the information processing terminal 9 uses Photoshop, GIMP, AffinityPhoto software to pre-process the video and image, and automatically cuts the part with halo characteristics in the image. The information processing terminal 9 can use programs such as Matlab and Python to calculate the parameters such as the Laplacian operator and Canny operator of the image. The ambient light intensity during image acquisition is adjustable, and the ambient light intensity has an impact on the image brightness. Therefore, before the test, a certain value of ambient light intensity can be set by adjusting the external light intensity, and the ambient light intensity can be recorded to facilitate the comparison and analysis of the microalgae density test results under different ambient light intensities.

[0085] In this embodiment, a green quantum dot film and a 450nm blue LED chip are selected to form an LED lighting device, and the LED lighting device is defined as a standard LED lighting device. The standard LED lighting device is used to generate a density of 3.15×10 8 ,9.46×10 8 , 2.21×10 9 , 3.47×10 9 4.73×10 9 5.99×10 9 ,7.88×10 9 The green algae samples with densities of 3.12×10 8 4.68×10 8 , 1.24×10 9 , 2.51×10 9 , 3.77×10 9 4.99×10 9 , 6.24×10 9The samples of brown algae were tested, and the imaging equipment was used to obtain the imaging photos of the microalgae solution under natural light conditions and under the conditions of lighting the LED lighting device, and the comparison was performed. The imaging photos of the microalgae solution under natural light conditions and under the conditions of lighting the LED lighting device were processed to obtain the clarity of the pictures and calculate the correlation factors (Laplace variance sharpness factor C L , structural similarity index factor C SSIM , local binary clarity factor C LBP , Gaussian blur factor C G , Sobel edge detection factor C SE And the Canny edge detection factor C CE etc.), RGB color difference and comprehensive color difference and other indicators.

[0086] Figure 3 The experimental result 1 of the embodiment shows the relationship curve between the density of the green algae solution and the sharpness calculation correlation factor when orange light is used as the background light. The results show that when the Laplace variance sharpness factor C is considered alone, L , structural similarity index factor C SSIM , local binary clarity factor C LBP , Gaussian blur factor C G , Sobel edge detection factor C SE Or the Canny edge detection factor C CE Under the conditions of the six clarity calculation related factors, there are problems such as the clarity value does not change significantly under the high density of microalgae, and the clarity value changes too fast and irregularly under the low density of microalgae. However, after further comprehensive consideration of the Laplace variance sharpness factor C L , structural similarity index factor C SSIM , local binary clarity factor C LBP , Gaussian blur factor C G , Sobel edge detection factor C SE And the Canny edge detection factor C CE By optimizing the corresponding weights of the six clarity calculation related factors, a comprehensive clarity curve with obvious slope changes under high-density microalgae and low-density microalgae conditions can be obtained. The above results show that the comprehensive clarity curve after optimizing the weights has obvious advantages over other methods in characterizing different microalgae densities.

[0087] Figure 4The experimental result 2 of the embodiment is as follows: When blue light is used as the background light, the horizontal brightness change curve of the image of the brown algae solution is shown. The results show that the horizontal brightness of the image of the brown algae solution shows an obvious inverted U-shaped change, with obvious boundaries, and the brightness distribution in the middle part is flat. When the density of microalgae is low, the horizontal brightness value is high, and the boundary change is most obvious. This is because the light intensity passing through the microalgae solution is high, and the light intensity is sensitive to the boundary of the light source; when the density of microalgae is high, the overall horizontal brightness value of the picture is low, and the boundary change is not obvious. This is because the light intensity passing through the microalgae solution is low, and after the light is scattered, the light intensity is not sensitive to the boundary of the light source. During the change of microalgae density, the overall horizontal brightness decreases unidirectionally as the density of microalgae increases. Therefore, the analysis results of the change of the horizontal brightness of the picture can better characterize the change process of the density of microalgae.

[0088] Figure 5 The experimental result 3 of the embodiment is: the RGB color difference change curve of the green algae solution imaging picture when orange light is used as the background light. The results show that the differences in R channel color difference, G channel color difference, and B channel color difference are large. Among them, the value of the R channel color difference is the lowest, and it hardly changes significantly with the density of microalgae; the value of the B channel color difference is the highest, and it has a similar change trend to the G channel color difference; the B channel color difference and the G channel color difference both show a linear change trend at low microalgae density, but show a trend towards saturation at high microalgae density. The difference between the R channel color difference, the G channel color difference or the B channel color difference is caused by the different absorption characteristics of algae to different colors of light. In summary, the R channel color difference, the G channel color difference or the B channel color difference alone cannot well characterize the linear or nonlinear change trend of the microalgae density. After calculating the comprehensive color difference, the R channel color difference, the G channel color difference or the B channel color difference in the comprehensive color difference is optimized, and the comprehensive color difference change curve with the microalgae density is obtained. The changing trend of comprehensive color difference under different microalgae densities shows that comprehensive color difference can describe the changes of microalgae density linearly and sensitively.

[0089] Figure 6 The experimental result 4 of the embodiment: when blue light, green light, orange light and red light are used as the background light, the calculation results of the comprehensive clarity of the imaging picture of the brown algae solution under different microalgae densities, and the corresponding fitting curves. The results show that the comprehensive clarity after optimizing the weights can well describe the changes in the density of microalgae under the background of different colors of light. The fitting curve can match the scatter plot obtained by the test well. In particular, the comprehensive clarity of orange light and red light does not show a rapid rise or a gentle change under the conditions of high microalgae density and low microalgae density, that is, the comprehensive clarity of orange light and red light with longer wavelengths has a good performance in characterizing high microalgae density and low microalgae density.

[0090] Figure 7The experimental result of Example 5 is the average accuracy of the density calculation of the brown algae solution when blue light, green light, orange light, and red light are used as the background light. The results show that under the test conditions of any color light, the average accuracy of the density calculation of the brown algae solution is generally higher than 90%, and the highest accuracy is 98%. Comparing the average accuracy of high-density and low-density microalgae solution samples, it can be found that, except for the results tested under green light conditions, the average accuracy of low-density microalgae solution samples is slightly higher. In general, Figure 7 The results show that the method of the present invention has a high test accuracy under different lighting test conditions and can be well used to evaluate the numerical changes in microalgae density.

[0091] Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the protection scope of the present invention. In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention can also be implemented in other ways different from those described herein, and those skilled in the art can make similar generalizations without violating the connotation of the present invention, so the present invention is not limited by the specific embodiments disclosed.

[0092] The technical effects and advantages of the present invention are as follows: (1) Technically, the present invention uses conventional quantum dots, phosphors and other materials to prepare light conversion materials with the support of existing technologies, which have the characteristics of high stability and easy preparation. (2) Technically, the present invention uses captured images as the monitoring object for feedback of microalgae density under the premise of LED lighting devices, which has the advantages of simple operation and high accuracy; the light source halo contained in the captured images has rich image features, which can generate timely feedback on the real-time changes in microalgae density; the images obtained by the imaging terminal can directly reflect the dynamic changes in microalgae density, without sampling, and the observation is convenient and accurate. (3) In theory, the present invention proposes a method for imaging a microalgae solution of known density under the conditions of LED lighting devices with different luminous colors and extracting image features, and further proposes through fitting and modeling that the different features of the imaging images of microalgae solutions under different microalgae densities can be accurately distinguished by the concepts of comprehensive color difference and comprehensive clarity; compared with the traditional method of directly shooting microalgae pictures, this method solves the problem that the imaging features of microalgae solutions under high-density and low-density conditions are not obvious and the degree of distinction is not high. (4) In theory, the present invention proposes a new method for evaluating the density of microalgae using concepts such as comprehensive color difference and comprehensive clarity. By calculating and optimizing parameters such as comprehensive color difference and comprehensive clarity, the efficiency of image feature extraction of microalgae solution imaging under high-density and low-density conditions can be improved, and a nonlinear fitting curve that better matches the experimental results can be obtained, solving the problem of inaccurate evaluation of microalgae density. (5) In theory, the present invention proposes a method for calculating the accuracy of microalgae density by comparing different light conversion materials and LED chip combinations through image color difference, clarity and other parameters; it can be used to evaluate the universality of the present invention under conditions such as different algae species, different imaging equipment, light conversion material types, and LED chip types. (6) The present invention is technically feasible, and after the technology of the present invention matures, it can be used for marine environment monitoring; under outdoor test conditions, all test instruments involved in the present invention can be used for underwater detection after waterproof design; (7) The function of the present invention is not only applicable to monitoring the density of a single microalgae species, but also to monitoring the density of multiple microalgae.

[0093] In addition, the following important aspects are also provided as auxiliary evidence for the novelty of the present invention:

[0094] The expected benefits and commercial value of the present invention after transformation are as follows: a. In marine sewage treatment, it is usually necessary to analyze the composition and characteristics of microalgae suspension in seawater sample suspensions. The method of combining lighting source and image analysis to obtain the density of microalgae suspension under different light sources can effectively evaluate the quality of seawater from the perspective of optical testing. b. At present, the cultivation of functional microalgae has occupied a certain market share nationwide. At the same time, the cultivation and monitoring of microalgae are also developing in the direction of intelligent suspension solution monitoring and evaluation. The microalgae density evaluation mechanism based on lighting source regulation proposed in the present invention can provide convenient technical support for this process. c. When light passes through different types of marine microalgae, the microalgae has different optical processes such as absorption and reflection of different colors of light. According to the above mechanism, the light transmission process of microalgae can be studied and analyzed by combining lighting source and image analysis, and further develop new optical equipment for testing the optical properties of microalgae solutions. In summary, whether from the perspective of marine sewage treatment, microalgae solution culture monitoring, or the key technology of developing new optical equipment related to microalgae, the present invention can effectively meet the technical needs;

[0095] The present invention fills the gap in the technology in the industry at home and abroad: current research mainly focuses on the fields of microscopic measurement of microalgae density and remote sensing measurement of microalgae distribution density, and there are few studies on measuring microalgae density by optical methods under near-field light field distribution conditions. Compared with the traditional microalgae density test method with multiple links such as microalgae sample collection, testing, calculation, and storage, the present invention has the characteristics of simplicity, high efficiency, and flexible light source replacement when monitoring microalgae density;

[0096] Whether the technical solution of the present invention solves the current technical problem: People have always hoped to obtain a reliable, accurate, fast, and suitable density monitoring device for different marine microalgae for use in seawater monitoring, microalgae cultivation monitoring and other fields. In the present invention, this problem is solved.

[0097] Whether the technical solution of the present invention overcomes technical prejudice: Traditionally, the measurement of microalgae density relies on specific instruments such as microscopes and photometers. However, the present invention proposes a low-cost, simple-to-operate, and flexible-assembled microalgae density measurement system and method, which can adjust the test distance, test angle, test light power, shooting focal length, etc. according to the thickness of the microalgae solution container. Compared with existing microscope tests, dry weight tests and other methods, the present invention has a simpler and more flexible test system; compared with existing spectrophotometer test methods, this method has more intuitive image display technology and more comprehensive image analysis methods.

[0098] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the embodiments of the present invention. For those skilled in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to list all the embodiments here. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the claims of the present invention.

[0099] In summary, although the present invention has been disclosed as above in terms of preferred embodiments, the above preferred embodiments are not intended to limit the present invention. A person skilled in the art may make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be based on the scope defined in the claims.

Claims

1. A method for measuring microalgae density based on illumination light source and image analysis, characterized in that: The following steps are involved: Step 1, characterizing the light-emitting properties of the LED chip (2), such as driving current, light power, and light-emitting spectrum; Characterizing the luminescent properties of the light conversion material layer (4), such as light conversion efficiency and luminescent spectrum; Characterize the density and algae species properties of the microalgae solution to determine the biological properties of the microalgae solution to be tested; Step 2, combining and fixing the LED chip (2) and the reflective cup (3) to form an LED lighting device with a specific lighting angle; fixing the light conversion material layer (4) to the cup mouth of the reflective cup (3) to form an LED lighting device that has excitation light, can realize light conversion, emits light of different colors, and the light intensity of which can be adjusted by current; Step 3, using the microalgae solution container to be tested (1) to hold the configured microalgae solution of fixed volume, different algae species and different densities; placing the microalgae solution container to be tested (1) on the lifting platform (6), adjusting the height and horizontal position of the lifting platform (6), the first bracket (7-1) and the second bracket (7-2) to ensure that the center points of the LED chip (2), the reflective cup (3), the light conversion material layer (4), the microalgae solution container to be tested (1) and the camera of the imaging device (5) are aligned and on the same straight line; Step 4, adjusting the camera of the imaging device (5) to ensure that the same focal length and the same aperture are maintained when measuring different microalgae solution samples; ensuring that in the same set of experiments, each time the microalgae solution is measured, the microalgae solution container (1) to be measured is placed at the same vertical and horizontal position of the lifting platform (6); the camera of the imaging device (5) is aimed at the halo passing through the microalgae solution to image, collect representative image data, and transmit it back to the information processing terminal (9); Step 5, the information processing terminal (9) pre-processes the collected image, including cutting the halo core part, unifying the image size, and separating the RGB channels; on this basis, the brightness, clarity and RGB color difference parameters of the pre-processed image are calculated.

2. The method for measuring microalgae density based on illumination light source and image analysis according to claim 1, characterized in that: Step 5 also includes: The selected clarity calculation related factors include: Laplace variance sharpness factor C L , structural similarity index factor C SSIM , local binary clarity factor C LBP , Gaussian blur factor C G , Sobel edge detection factor C SE And the Canny edge detection factor C CE ; After normalization, the above factors are added according to the set weights to obtain the comprehensive clarity C A ; Comprehensive clarity C A The expression is as follows: C A =αC L +βC SSIM +γC LBP +δC G +εC SE +ζC CE ; Among them, a, b, c, d, ε and ζ are the Laplace variance sharpness factors C L , structural similarity index factor C SSIM , local binary clarity factor C LBP , Gaussian blur factor C G , Sobel edge detection factor C SE And the Canny edge detection factor C CE The weight coefficient of Calculation method of RGB color difference: extract the RGB value of each pixel from the image, and perform difference calculation with the reference standard color to obtain the color difference of each color channel, and then perform Euclidean distance calculation according to the preset weight of each channel to finally obtain the comprehensive color difference.

3. The method for measuring microalgae density based on illumination light source and image analysis according to claim 2, characterized in that: Also includes: Step 6: Keep the illumination conditions unchanged, replace the same type and different density of microalgae solution for image acquisition, and repeat steps 1 to 5; obtain the relevant factors of each clarity calculation and the comprehensive clarity C A , RGB channel color difference, comprehensive color difference indicators under different density microalgae solution conditions; comprehensive clarity C A The scatter plots obtained under different microalgae density conditions were tested for nonlinear fitting to find the optimal nonlinear fitting function; Step 7: Optimize the overall clarity C A Nonlinear fitting curves under different microalgae densities improve the correlation and smoothness of the scatter points and fitted curves; Step 8: The optimized comprehensive clarity C obtained in step 7 A The scatter plots obtained under different microalgae density conditions were tested for nonlinear fitting, and the nonlinear fitting curves under different color illumination conditions were compared; Step 9, after testing the microalgae solution of known density, use steps 1 to 8 to perform imaging, image processing, image feature extraction and analysis on the microalgae solution of unknown density to obtain the comprehensive clarity C under different luminous color conditions. B The index of the comprehensive clarity C obtained by referring to the microalgae solution sample with known density A The nonlinear fitting curve with the microalgae density was used to obtain the comprehensive clarity C B The corresponding density of the microalgae solution is D B ; Step 10, by measuring the comprehensive clarity index of the microalgae sample with known density under different luminous color conditions, and inferring the unknown microalgae density; the accuracy η is D B With D A The absolute value of the difference between A The formula for calculating the microalgae density accuracy η is as follows: η=|D B -D A | / D A , where D A The microalgae density is obtained after testing the microalgae density by the traditional manual counting method; Calculate the value of the accuracy η of the microalgae density measurement method test under different luminous color conditions; calculate the value of the accuracy η of the microalgae density measurement method test under different algae species conditions; through the analysis of the accuracy η, further optimize the weights of the clarity-related calculation factors for calculating the comprehensive clarity, and improve the final calculated accuracy η.

4. The method for measuring microalgae density based on illumination light source and image analysis according to claim 3, characterized in that: Step S7 includes: selecting appropriate clarity calculation related factor calculation weights and RGB color difference calculation weights according to the illumination wavelength to obtain a comprehensive clarity C with a better fitting result. A Nonlinear fitting curves under different microalgae densities; First, the comprehensive clarity C is calculated using the default weights. A , and plot the comprehensive clarity C A and the relationship curve between the density of microalgae; then, analyze the abnormal points in the curve, and try to reduce the weight of the clarity calculation related factors that cause the abnormalities step by step; try to increase the weight of the clarity calculation related factors with good linearity appropriately; in this way, gradually adjust the weights of different clarity calculation related factors, and finally make the comprehensive clarity C A There is a good linear correlation between the density of microalgae and the 5. The method for measuring microalgae density based on illumination light source and image analysis according to claim 4, characterized in that: Step S7 calculates the comprehensive definition C A When optimizing the weights of the relevant factors for different clarity calculations, the default weights of the relevant factors for clarity calculations can be adjusted according to the actual curve shape, or some verified weights can be directly used to optimize the data in accordance with the principle of not expanding local anomalies and giving full play to the advantages of the optimal interval.

6. A microalgae density measurement system based on illumination light source and image analysis, used to implement the steps of a microalgae density measurement method based on illumination light source and image analysis according to any one of claims 1 to 5, characterized in that: The invention comprises a container (1) for a microalgae solution to be tested, an LED lighting device, an imaging device (5), a lifting platform (6), a first bracket (7-1), a second bracket (7-2), a current source (8) and an information processing terminal (9); the container (1) for a microalgae solution to be tested is fixed on the top of the lifting platform (6); the first bracket (7-1) and the second bracket (7-2) are arranged on both sides of the lifting platform (6); the LED lighting device is arranged on the top of the first bracket (7-1); the imaging device (5) is arranged on the top of the second bracket (7-2); the LED lighting device and the imaging device The equipment (5) is arranged in alignment with the microalgae solution container (1) to be tested; the LED lighting device is electrically connected to the current source (8), the imaging device (5) is electrically connected to the information processing terminal (9), and the information processing terminal (9) is used to obtain information from the imaging device (5) and perform calculation and analysis; wherein the LED lighting device comprises an LED chip (2), a reflective cup (3), and a light conversion material layer (4) covering the light emitting surface of the reflective cup (3); the current source (8) supplies power to the LED chip (2) to control the current of the LED chip (2); The container (1) for the microalgae solution to be tested is used to hold microalgae solutions of different types and densities; the LED chip (2) is used as an excitation light source for the light conversion material; the reflective cup (3) is used to collect the light generated by the LED chip (2), guide the light to pass through the light conversion material layer (4), and excite the light conversion material layer (4) to emit light of a specific wavelength; at the same time, the edge size of the reflective cup (3) matches the edge size of the light conversion material layer (4), and is used to fix the light conversion material layer (4); the lifting platform (6) is used to adjust the microalgae solution to be tested. The vertical height of the algae solution container (1) is such that the halo emitted by the light conversion material layer (4) passes through the central position of the microalgae solution container (1); the imaging device (5) is used to record the halo state of the light emitted by the LED chip (2) after passing through the reflective cup (3) and the light conversion material layer (4) and then passing through the microalgae solution container (1) to be measured; before imaging, the positions of the first bracket (7-1) and the second bracket (7-2) can be adjusted to meet the shooting focal length requirements of the imaging device (5) and achieve the best imaging effect.

7. The microalgae density measurement system based on illumination light source and image analysis according to claim 6, characterized in that: The light emission band of the LED chip (2) is blue light or ultraviolet light. When the thickness of the microalgae solution container (1) to be tested is relatively thick, a relatively high-power LED chip can be selected to emit light, so as to ensure that the emitted light has relatively high penetration. When the thickness of the microalgae solution container (1) to be tested is relatively thin, a relatively low-power LED chip can be selected to emit light, so as to ensure that the halo will not be overexposed when imaging the imaging device (5).

8. The microalgae density measurement system based on illumination light source and image analysis according to claim 7, characterized in that: The material of the light conversion material layer (4) is any one of the light conversion materials in fluorescent powder, quantum dots, perovskite or organic dyes; the reflective cup (3) is made of aluminum or acrylic material, and its inner wall is a smooth or rough texture structure; the microalgae solution container (1) to be tested is made of transparent acrylic, transparent glass, or transparent quartz material, and the microalgae solution container (1) to be tested is used to store one or more algae from common microalgae such as Navicula, Thalassiosira, Haematococcus pluvialis, and Oocystis.

9. The microalgae density measurement system based on illumination light source and image analysis according to claim 8, characterized in that: The imaging device (5) is a camera or a mobile phone, wherein the aperture of the imaging device (5) is adjustable and can be adjusted to the minimum aperture that can just capture the halo at the highest density of the microalgae solution as required.

10. The microalgae density measurement system based on illumination light source and image analysis according to claim 9, characterized in that: The information processing terminal (9) is a desktop computer or a tablet computer, and is used for image processing and analysis; wherein the information processing terminal (9) uses Photoshop, GIMP, Affinity Photo software to perform preliminary processing on videos and images, and to crop the portion of the image with halo characteristics.

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