Image processing method and particle analysis system

Abstract

There is a known analytical processing technique for calculating the concentration and particle diameter of a dispersion liquid based on an image obtained by irradiating a dispersion liquid with a laser beam and capturing scattered light from particles in the dispersion liquid. However, expanding the imaging range of an imaging device increases the number of particles to be analyzed, which may slow down the speed of the analytical processing. To solve this problem, the image processing method of the present invention acquires an image of an area of ​​the dispersion liquid where the laser beam is incident using an imaging device, sets an analysis area in the image, and performs image processing on this analysis area to calculate the particle concentration or particle diameter in the analysis area.

Description

[Technical Field]

[0001] The present invention relates to an image processing method and a particle analysis system for more quickly calculating the concentration and particle diameter of a dispersion liquid based on an image obtained by irradiating a dispersion liquid with laser light and capturing an image of scattered light from particles in the dispersion liquid. [Background technology]

[0002] BACKGROUND ART Conventionally, there is known a technique for determining the concentration of a dispersion or the particle diameter of particles in a dispersion based on an image obtained by irradiating a dispersion with laser light and capturing an image of scattered light from particles in the dispersion.

[0003] For example, Patent Document 1 describes a method of irradiating a dispersion containing standard particles with laser light, capturing the scattered light with a camera, and measuring the concentration of the dispersion based on the number of bright spots contained in the image. Patent Document 2 describes a method of irradiating a dispersion with laser light, capturing the particle movement by continuously capturing images of the particle movement with an imaging device, and calculating the particle diameter from the Brownian motion of the particles using the Stokes-Einstein equation. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2024-061147 [Patent Document 2] Japanese Patent Application Publication No. 2020-109419 Summary of the Invention [Problem to be solved by the invention]

[0005] In this way, when irradiating a dispersion with a laser and imaging the irradiated area, the imaging area may be set wide to observe a wide range of particles in the dispersion. For example, when the concentration of the dispersion is low, it may be necessary to widen the imaging area to check whether there is any uneven distribution of particles.

[0006] However, when the imaging range is expanded, the number of particles to be analyzed increases, which leads to problems such as calculation time being required to obtain the particle size distribution of a dispersion liquid, making it impossible to obtain results immediately. [Means for solving the problem]

[0007] In order to solve the above problem, the image processing method of the present invention acquires an image of an area where laser light is incident on a dispersion liquid using an imaging device, specifies an analysis area in the image, and performs image processing on this analysis area to calculate the particle concentration or particle diameter in the analysis area.

[0008] In addition, in order to solve the above-mentioned problems, the particle analysis system of the present invention includes an imaging device that captures an image of an area where laser light is incident on a dispersion liquid to obtain the captured image, an image processing device that generates a GUI (Graphical User Interface) image including the captured image, a display device that displays the GUI image, and an input device connected to the image processing device, wherein the input device receives from a user an indication of an analysis area for the captured image included in the GUI image, and the image processing device performs image processing on the analysis area to calculate the particle concentration or particle diameter in the analysis area. [Effects of the Invention]

[0009] The present invention enables a system that analyzes particles by irradiating a dispersion with a laser and performing image processing to speed up the analysis process even when the imaging range is expanded. Furthermore, by providing a graphical user interface, the system can improve user convenience while realizing faster analysis processing. [Brief explanation of the drawings]

[0010] [Figure 1] 1 illustrates a particle analysis system according to an embodiment of the present invention. [Figure 2] 1A and 1B are diagrams illustrating an example of a captured image captured by an imaging device according to an embodiment of the present invention. [Figure 3]FIG. 1 is a flowchart of an image processing method according to an embodiment of the present invention. [Figure 4] 10A and 10B are diagrams for explaining setting of an analysis area in an image processing method according to an embodiment of the present invention. [Figure 5] 10A to 10C are diagrams for explaining particle identification in an image processing method according to an embodiment of the present invention. [Figure 6] FIG. 2 is a diagram showing an example of a GUI according to an embodiment of the present invention. [Figure 7] FIG. 1 is a diagram for explaining an imaging range according to an embodiment of the present invention; [Figure 8] FIG. 1 is a diagram showing an example of an observation image according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0011] Hereinafter, embodiments of the present invention will be described with reference to the drawings. However, the components described are merely examples and are not intended to limit the technical scope of the present invention.

[0012] <Embodiment> 1 is a diagram showing a particle analysis system 100 according to the present invention. The particle analysis system 100 includes a laser light source 10, a container 20, an imaging device 30, an image processing device 40, a display device 50, a GUI (Graphical User Interface) 60, and an input device 70.

[0013] A semiconductor laser can be used as the laser light source 10. The laser light source 10 emits laser light 11 into a container 20 containing the dispersion liquid, and outputs light of a wavelength that can cause Rayleigh scattering light to be emitted from the fine particles and ultrafine bubbles contained in the dispersion liquid. For example, a semiconductor laser with a wavelength of 405 nm can be used. The irradiation direction of the laser light 11 is the X direction when the XYZ directions are set as shown in Figure 1.

[0014] To expand the imaging range, a lens or the like may be added to the optical path to form the laser light 11 into a sheet, thereby expanding the irradiation range. For example, the laser light 11 can be formed into a sheet by using a GRIN lens or a cylindrical lens. When a GRIN lens is used, the laser light 11 can be formed into a sheet by reducing the laser spot diameter in the Y-axis direction shown in FIG. 1 with a first GRIN lens and expanding the laser spot diameter in the Z-axis direction with a second GRIN lens. After forming the laser light 11 into a sheet, an aperture may be placed to cut off portions of the laser with weak intensity, or the laser light may be passed through a diffraction grating to uniformly shape the beam intensity distribution before entering the container 20.

[0015] The container 20 is made of glass, transparent plastic, or the like, and can contain a dispersion liquid. For example, the container 20 has a capacity to contain a maximum of 500 mL of dispersion liquid, but is not limited to this. The dispersion medium is, for example, pure water or city water. Note that the particle analysis system 100 is not limited to the container 20, and may also be configured to capture an in-line flow to observe scattered light from the dispersion liquid.

[0016] The imaging device 30 is an imaging device such as a camera equipped with a lens such as a telecentric lens, and captures an image by setting an imaging range within the irradiation area of ​​the container 20 where the laser light 11 is irradiated. The imaging device 30 generates captured images by continuously capturing images of the imaging area at predetermined intervals. The imaging device 30 is connected to an image processing device 40, and can transmit the captured images to the image processing device 40. Figure 2 shows an example of an image captured by the imaging device 30. As shown in Figure 2, scattered light from particles appears as bright spots. Note that Figure 2 is an image of pure water containing UFB (ultra-fine bubbles) with a particle size of approximately 100 nm.

[0017] 1, the imaging device 30 is disposed so as to capture an image from a direction (Y direction) perpendicular to the X direction, which is the irradiation direction of the laser light 11. However, this is not limiting, and it is sufficient if the imaging device can capture an image of scattered light from particles in the dispersion liquid.

[0018] The imaging range of the imaging device 30 can be set to, for example, 5 [mm] x 1.4 [mm], but is not limited to this. The imaging range can be calculated using the distance to the object to be imaged, the focal length of the lens, and the sensor size. The volume of the dispersion liquid in the imaging range can be calculated based on the imaging range and depth of field of the imaging device 30. For example, if the depth of field of the imaging device 30 is 44 [μm], then the volume is calculated as 5 x 1.4 x 44 = 0.308 mm. 3 is the volume of the dispersion liquid in the imaging range.

[0019] The imaging range is set to at least fall within the irradiation range of the laser beam 11. This imaging range will be described with reference to Fig. 7. Fig. 7 is a cross-sectional view of the irradiation range of the laser beam 11 shown in Fig. 1 along the XZ plane.

[0020] As shown in Fig. 7, the height M of the imaging range 710 in the direction perpendicular to the traveling direction of the laser beam 11 (the X direction in Fig. 1) is set to be equal to or less than 1 / 2 of the width L of the laser beam 11. In other words, M ≦ 1 / 2 × L. The center of the imaging range 710 is set to be on the laser optical axis 720. This is because, due to the characteristics of laser beams, the intensity in the Z direction attenuates with increasing distance from the optical axis direction. If this setting is not made, the brightness value of the scattered light in the captured image may vary between the edges and the center.

[0021] The image processing device 40 is, for example, a PC (personal computer), and performs various image processing on the captured image sent from the imaging device 30. The image processing device 40 is also connected to an input device 70 operated by a user, such as a keyboard 70-1 or a mouse 70-2, and receives instructions from the user via a GUI 60 and performs processing in accordance with the instructions. The image processing method according to the present invention is implemented in the image processing device 40.

[0022] The display device 50 is, for example, a liquid crystal monitor, and is connected to the image processing device 40, and is capable of displaying images captured by the imaging device 30, images processed by the image processing device 40, etc. The display device 50 also displays a GUI image generated by the image processing device 40 as a GUI 60. The GUI 60 provides various information, and can also accept instructions from the user via the input device 70 and visually display the processing results in response to those instructions.

[0023] 6 shows an example of the GUI 60. The GUI 60 includes a captured image 420 captured by the imaging device 30. When analysis areas 421 to 423 are set, observation images 631 to 633, which are images within those areas, can be included. The observation images 631 to 633 may display the analysis areas 421 to 423 at the same size or may be enlarged.

[0024] FIG. 3 shows the flow of an image processing method 300 executed by the image processing device 40. First, in S310, an analysis area is set in the captured image. The analysis area is a region on the image divided for determining the concentration of a dispersion within this range or the particle diameter of any particle within this range. FIG. 4 is a diagram for explaining S310. FIG. 4(A) shows a captured image 410 and an analysis area 411. For example, while checking the captured image 410 displayed on the GUI 60, the user operates the mouse 70-2 or keyboard 70-1 connected to the image processing device 40 to specify the size and position of the analysis area 411, thereby setting any region on the captured image 410 as the analysis area.

[0025] The number of analysis areas set in S310 is not limited to one, and may be multiple. For example, as shown in Fig. 4(B) or Fig. 6, multiple analysis areas such as analysis areas 421 to 423 can be set for a captured image 420. When multiple analysis areas are set, the sizes of the respective analysis areas may be the same or different.

[0026] When an analysis area is set, the analysis area may be displayed separately from the captured image in the GUI 60. For example, as in the GUI 60 shown in Fig. 6, when an analysis area 421 is set for the captured image 410, an observation image 631, which is an image of the analysis area 421, can be included. Similarly, the analysis areas 422-423 can be included in the GUI 60 as observation images 632-633. Note that the observation image may be an enlarged display of the image of the analysis area.

[0027] Next, in S320, an analysis area to be subjected to particle analysis in S350 is specified for the analysis area set in S310. For example, as shown in FIG. 4(A), if one analysis area is set in S310, that analysis area is specified in S320. On the other hand, as shown in FIG. 4(B), if multiple analysis areas are set in S310, at least one analysis area is specified. Note that if there are multiple analysis areas, all of the analysis areas may be specified. If there are multiple analysis areas, analysis area 421, which is one of analysis areas 421 to 423 shown in FIG. 4(B), may be specified, or all of analysis areas 421 to 423 may be specified. Note that only a portion of the analysis area may be specified, such as analysis area 421 and analysis area 422.

[0028] When specifying an analysis area via GUI 60, the user operates mouse 70-2 to move the pointer over the analysis area or its observation image displayed on GUI 60 and specify it by clicking, or by clicking to display a subwindow for selection, prompting the user to specify which analysis area to specify.

[0029] Next, in S330, the user specifies whether to perform concentration analysis or particle size analysis for the analysis region specified in S320. It is also possible to specify both concentration analysis and particle size analysis. The specification in S330 may be made, for example, by right-clicking the mouse 70-2 on the observed image 631 to display a menu of options for "concentration analysis" and "particle size analysis," allowing the user to select one option.

[0030] The concentration analysis described in this specification is intended to determine the number concentration. To determine the number concentration of the entire captured image, the number of bright spots, which are scattered light from particles contained in the entire captured image, is counted, and the number of bright spots is multiplied by 0.308 mm, which is the volume of the dispersion liquid determined from the captured image. 3 The value obtained by dividing by (5 [mm] × 1.4 [mm] × 44 [μm] as mentioned above) is the number concentration of the dispersion. When determining the number concentration for a partial region of a captured image, such as an analysis region, the area of ​​the partial region is calculated, and the volume of the dispersion in the partial region is determined by multiplying the calculated area by the depth of field, and the number of bright spots in the partial region is then divided by the volume of the dispersion in the partial region. The area of ​​the partial region can be calculated based on the size of the partial region relative to the captured image.

[0031] Next, in S340, particles within the specified analysis area are identified. FIG. 5 is a diagram for explaining the identification of particles in S340. In identifying particles, for example, a group of pixels showing a predetermined brightness value or more or a group of pixels having a feature amount that satisfies a predetermined condition can be identified as particles. For example, with respect to the analysis area 500 shown in FIG. 5, particles such as particles 501 and 502 can be identified as particles based on brightness values ​​and feature amounts. Note that particles other than particles 501 and 502 can also be identified by similar processing.

[0032] Next, in S350, an analysis process is performed. The analysis process is to perform the concentration analysis or particle size analysis (including both) specified in S330 on the analysis area by image processing. The concentration analysis counts the number of particles identified in S340 and determines the number concentration based on the number of particles in the analysis area and the volume of the analysis area. As shown in FIG. 6, when a concentration analysis is performed on the analysis area 421, the number concentration may be displayed in an area 641 adjacent to the observation image 631. Similarly, when a concentration analysis is performed on the analysis areas 422-423, the number concentration can be displayed in areas 642-643.

[0033] Particle size analysis involves determining the particle size of each particle identified in S340. Specifically, the diffusion coefficient is calculated based on the particle movement amount determined from multiple captured images after a predetermined time has elapsed, and the particle size is then calculated by substituting this into the Stokes-Einstein equation using information on the temperature and viscosity of the dispersion. Figure 8 shows an example of an observation image obtained when particle size analysis is performed on an analysis area. As shown in observation image 800 in Figure 8, the particle size is displayed in the upper right corner of the particle for which particle size analysis was performed, allowing the user to visually grasp each particle size. The numerical values ​​in observation image 800 are in [nm]. Note that, as in trajectory 810, multiple captured images may be used to superimpose the particle movement on observation image 800 based on the identified particle's movement position, allowing the user to see how the particle moved, as in trajectory 810.

[0034] Next, in S360, it is determined whether there are any unanalyzed particles in the analysis region. If concentration analysis is specified in S330, this process is skipped and the image processing method 300 ends. If there are unanalyzed particles in the analysis region (S360; YES), the process returns to S340 and the unprocessed particles are identified. On the other hand, if there are no unanalyzed particles in the analysis region (S360; NO), the image processing method 300 ends.

[0035] Although the flow of the image processing method 300 has been described above using FIG. 3, the order of the steps is not limited to this. For example, before setting the analysis area in S310, a process for specifying whether to perform concentration analysis or particle size analysis in S330 may be executed. In this way, the steps can be interchanged without changing the spirit of the invention. Furthermore, as in the following modified example, some steps can be modified without deviating from the spirit of the invention.

[0036] <Modification 1> Automatic calculation of the size of the analysis area In S310, the analysis area is set based on the user's instructions, but the optimal size of the analysis area may be set automatically based on the concentration of the dispersion liquid and the number of particles that require analysis processing.

[0037] For example, suppose the captured image is 5000 x 1200 pixels (6,000,000 pixels). Then, suppose that the result of counting the number of particles in this captured image reveals that there are 1,000 particles. In this case, if the particles are evenly distributed, it would be sufficient to divide the image into 6,000 pixel intervals.

[0038] Here, for example, if the number of particles to be subjected to particle size analysis in S350 is set to 50, then 6,000 x 50 = 300,000 pixels should be set as the analysis region. If the region is divided into squares, the size of the analysis region can be set to 550 x 550 based on the square root of 300,000. Note that the number of particles to be subjected to particle size analysis is not limited to 50 and can be set arbitrarily. In this way, the size of the analysis region may be determined first before S310, and then the process may proceed to S310 to determine the position of the analysis region.

[0039] <Modification 2> Specifying particles to be analyzed by particle size analysis When performing particle size analysis, the user may specify in advance which particles are to be analyzed by size analysis. For example, before step S350, the user may click the mouse 70-2 on the observation image to specify the particles, and the particle size analysis is performed on the specified particles.

[0040] <Variation 3> Parallel processing of analysis area If multiple analysis regions are set in S310, the processes of S340 and S350 may be performed in parallel, which means that if the image processing device 40 is equipped with a multi-core CPU, the processing speed can be increased.

[0041] <Modification 4> Subdividing the analysis area and parallel processing The analysis area may be further divided into a plurality of areas, and the divided analysis areas may be processed in parallel for analysis.

[0042] <Modification 5> Determining the presence or absence of convection and resetting If convection occurs in the dispersion, it may affect the Brownian motion of the particles and prevent accurate particle size analysis. Therefore, after the analysis area is set in S310, it may be determined whether or not convection exists in the analysis area, and if convection exists, the user may be prompted via GUI 60 to reset the analysis area and set a different analysis area.

[0043] To determine whether or not convection is occurring, similar to S340, particles in the analysis area are identified and their movement components are calculated using multiple captured images. Next, other particles in the vicinity are identified and their movement components are calculated in the same way. If these movement components are in the same direction for multiple particles, it can be determined that convection is occurring.

[0044] <Modification 6> Limiting the number of particles to be analyzed In S360, it is determined whether there are any unanalyzed particles in the analysis region, and if a predetermined number of particles have been analyzed, the image processing method 300 may be terminated. When analyzing standard particles, the particle size is almost uniform, so the number of particles to be processed can be reduced.

[0045] <Variation 7> No GUI The image processing method 300 is performed by the user entering predetermined instructions via the GUI 60, but can also be performed without using the GUI 60 by presetting the items to be specified; for example, the size and position of the analysis area may be fixed in advance. Also, the process to be performed may be pre-set without the user specifying it in S330.

[0046] <Modification 8> High precision First, before executing image processing method 300, the number concentration of the dispersion liquid is calculated based on the captured image. Then, when executing image processing method 300 to perform particle size analysis, if the calculated number concentration of the analysis region is not within a predetermined range for the number concentration of the captured image, the user may be prompted to reset the analysis region via GUI 60. This prevents accidentally setting an analysis region with few particles for, for example, a low-density dispersion liquid, and prompts the user to set a new analysis region that is within an appropriate concentration range, thereby improving accuracy.

[0047] <Modification 9> High precision (removal of foreign matter) If a foreign object is found in the analysis area, the user can be prompted to reset the analysis area via the GUI 60. Foreign objects can be determined by setting various conditions when identifying particles based on bright points, such as whether the brightness value of the bright point is a predetermined value or higher, or whether the shape of the bright point is not spherical, and by doing so, it can be determined whether the bright points included in the analysis area are foreign objects.

[0048] <Modification 10> Setting the analysis order based on concentration When two or more analysis regions are specified and particle size analysis is performed for each analysis region, the particle concentration in each analysis region may be calculated first, and particle size analysis may be performed in order from the analysis region with the lowest particle concentration. This allows particle size analysis to be performed starting with the analysis region with the lowest processing volume, and allows the user to be notified of the progress of the processing results as quickly as possible. [Explanation of symbols]

[0049] 10 Laser light source 20 containers 30 Imaging device 40 Image processing device 50 Display device 60 GUI 70 Input Device 100 Particle Analysis System

Claims

1. An image of the area of ​​the dispersion liquid where the laser light is incident is captured by an imaging device, and an image is obtained. setting an analysis area in the captured image; image processing of the analysis area to calculate the particle concentration or particle diameter in the analysis area; 1. An image processing method, comprising: an image processing method for calculating the particle diameter when the particle concentration in the analysis area is within a predetermined range with respect to the particle concentration of the dispersion determined based on the captured image;

2. An image of the area of ​​the dispersion liquid where the laser light is incident is obtained by an imaging device; setting an analysis area in the captured image; image processing of the analysis area to calculate the particle concentration or particle diameter in the analysis area; 1. An image processing method, comprising: An image processing method that determines whether or not there is convection in the analysis area, and resets the analysis area if there is convection.

3. 3. The image processing method according to claim 1, wherein the imaging range in the vertical direction of the imaging device is equal to or smaller than half the width of the laser light, and the center of the imaging range is on the optical axis of the laser light.

4. 3. The image processing method according to claim 1, wherein the size of the analysis area is based on the particle concentration of the dispersion and the number of particles that require analysis.

5. 3. The image processing method according to claim 1, wherein the particle concentration in the analysis area is calculated by dividing the number of bright spots contained in the analysis area by the volume of the dispersion liquid calculated by multiplying the area of ​​the analysis area by the depth of field.

6. The image processing method according to claim 1 , wherein when two or more analysis regions are set, the image processing is performed in parallel.

7. The image processing method according to claim 1 or 2, wherein the calculation of particle diameters is performed for designated particles in the analysis region.

8. an imaging device that captures an image of a region of the dispersion liquid where the laser light is incident, and acquires a captured image; an image processing device that generates a GUI (Graphical User Interface) image including the captured image; a display device that displays the GUI image; an input device connected to the image processing device, the input device receives, from a user, an instruction to set an analysis area for the captured image included in the GUI image; The image processing device processes an image of the analysis area to calculate a particle concentration or a particle diameter in the analysis area, the image processing device calculates a particle diameter when the particle concentration in the analysis area is within a predetermined range with respect to the particle concentration of the dispersion liquid determined based on the captured image. Particle analysis system.

9. an imaging device that captures an image of a region of the dispersion liquid where the laser light is incident, and acquires a captured image; an image processing device that generates a GUI (Graphical User Interface) image including the captured image; a display device that displays the GUI image; an input device connected to the image processing device, the input device receives, from a user, an instruction to set an analysis area for the captured image included in the GUI image; The image processing device processes an image of the analysis area to calculate a particle concentration or a particle diameter in the analysis area, the image processing device determines whether or not convection exists in the analysis region, and resets the analysis region if convection exists; Particle analysis system.

10. 10. The particle analysis system according to claim 8, wherein the imaging range in the vertical direction by the imaging device is equal to or less than half the width of the laser light, and the center of the imaging range is on the optical axis of the laser light.

11. 10. The particle analysis system of claim 8 or 9, wherein the size of the analysis area is based on the particle concentration of the dispersion and the number of particles requiring analysis processing.

12. 10. The particle analysis system according to claim 8, wherein the particle concentration in the analysis region is calculated by dividing the number of bright spots contained in the analysis region by the volume of the dispersion liquid calculated by multiplying the area of ​​the analysis region by the depth of field.

13. A particle analysis system as described in claim 8 or 9, wherein when two or more analysis areas are set, the image processing is performed in parallel.

14. A particle analysis system as described in claim 8 or 9, wherein the calculation of particle diameter is performed for specified particles in the analysis area.

15. 10. A particle analysis system according to claim 8 or 9, wherein the GUI image comprises an image of the analysis area.

Images