JP4072489B2 - Particle image analysis method and apparatus, program and recording medium - Google Patents

Description

  The present invention relates to a particle image analysis method and apparatus for obtaining information on particles by imaging particles and analyzing the image of the particles.

As a background art of the present invention, a flow cell for converting a flow of a particle suspension into a flow surrounded by a sheath liquid, light irradiation means for irradiating light to the converted suspension flow, and irradiated particles An image analysis unit that analyzes the captured particle image, and a display unit, the image analysis unit measures the particle data about the area and the perimeter of each captured particle image, A calculation means for calculating the particle and the circularity from the particle data, a histogram based on the particle size frequency data based on the particle size, and a two-dimensional scattergram based on two parameters corresponding to the particle size and the circularity A chart creation means for displaying on each display means, a storage means for storing each captured particle image, and a particle image calling means for collectively displaying each particle image stored in the storage means on the display means It made it the particle image analyzing apparatus according to claim is known (for example, see Patent Document 1).
Japanese Patent No. 3411112

In recent years, in the manufacturing process and quality control process of various particulate materials such as fine ceramic particles and toner, pigments, cosmetic powders, food additives, chemicals, various information about each particle of the particulate material has been measured, It is becoming important to analyze particles.
However, the conventional method and apparatus can determine the particle diameter, circularity, or aggregation degree of particles, but cannot determine other particle information, for example, the degree of unevenness of particles.
The present invention has been made in consideration of such circumstances, and provides a particle image analysis method and apparatus capable of calculating the degree of unevenness of particles from particle images obtained by imaging particles. is there.

  The present invention is characterized in that the number of inflection points and the perimeter of the particle contour of image data obtained by imaging the particles are obtained, and the degree of unevenness of the particles is obtained from the number of inflection points and the perimeter. A particle image analysis method is provided.

  The present invention also provides a binarization unit that binarizes image data obtained by imaging particles, and a chain code that tracks contour pixels forming the contours of the binarized image data particles. And an analysis unit that obtains the number of inflection points of the particle contour and the perimeter of the particle using the chain code, and obtains the degree of irregularity of the particle from the number of inflection points and the perimeter The present invention provides a particle image analyzer characterized by the above.

  According to the present invention, the degree of unevenness of a particle image can be easily obtained from the number of inflection points of the particle and the peripheral length, and new information necessary for particle analysis is provided.

The object of image analysis of the present invention includes fine ceramics, pigments, inorganic powders such as cosmetic powders, and organic powders such as food additives, and may be polycrystalline particles. .
In the particle image analysis method of the present invention, the number of inflection points and the perimeter of the particle contour of image data obtained by imaging the particle are obtained, and the degree of unevenness of the particle is determined from the number of inflection points and the perimeter. It is characterized by seeking.
The degree of unevenness is the ratio of the number of bending points to the perimeter.

The particle image analysis apparatus according to the present invention includes a binarization unit that binarizes image data obtained by imaging particles, and a contour pixel that forms a particle contour of the binarized image data The edge trace part for obtaining the chain code for tracking the particle, the number of inflection points of the particle outline and the circumference of the particle are obtained using this chain code, and the degree of unevenness of the particle is obtained from the number of the inflection points and the circumference And an analysis unit.
The degree of unevenness is the ratio of the number of bending points to the perimeter.
The binarization unit, the edge trace unit, and the analysis unit can be integrally configured by a microcomputer or a personal computer including a CPU, ROM, and RAM.

The particle image analyzer of the present invention includes a flow cell that converts a suspension containing particles into a suspension flow, a light irradiation unit that irradiates light to the converted suspension flow, and an irradiated particle. You may further provide the imaging part which images.
In this case, the flow cell is a cell that can be converted into a fine or flat flow by a hydrodynamic effect by wrapping the flow of the particle suspension in a sheath liquid, and includes a conventionally known one. Can be used.

In addition, about the sheath liquid supplied to a flow cell, it is preferable to select the kind according to the property (particle | grains) and the property of a solvent).
Further, it is preferable to use a strobe or a laser light source that emits a pulsed light for the light irradiation unit.
Although a light source that emits light continuously can be used, in this case, it is necessary to provide a shutter in the imaging unit. A video camera that captures a general two-dimensional image can be used for the imaging unit.

The light irradiation unit and the imaging unit are arranged with the flow cell interposed therebetween, and when the particle suspension is converted into a flat flow in the flow cell, the light irradiation unit emits light perpendicular to the flat surface of the particle suspension flow. And the imaging unit is preferably arranged on the optical axis.
Further, the present invention obtains the number of inflection points and the circumference of the particle from the image data obtained by imaging the particle, and obtains the degree of irregularity of the particle from the number of the inflection points and the circumference. A featured particle image analysis program is provided.
The present invention also provides a computer-readable recording medium on which the program is recorded.

  This recording medium may be a memory that is processed by a microcomputer, such as a ROM, or a program medium provided with a program reading device as an external storage device and read by being inserted therein. Also good.

  In either case, the stored program may be configured to be accessed and executed by a microprocessor, or may be downloaded to a program storage area of a computer and executed. Good. It is assumed that this download program is stored in advance in the particle image analyzer.

  Here, the program medium is a storage medium configured to be separable from the apparatus, such as a tape system such as a magnetic tape or a cassette tape, a magnetic disk such as a floppy (registered trademark) disk or a hard disk, or a CD-ROM / MO / MD. Media that carries a fixed program, including disk systems such as / DVD, optical disks, IC cards (including memory cards) / optical cards, and semiconductor memories such as mask ROM, EPROM, EEPROM, flash ROM, etc. It may be.

  In addition, the particle image analysis apparatus of the present invention may be configured as a system that can be connected to a communication network including the Internet, and the recording medium may be a medium that carries the program in a fluid manner so as to download the program from the communication network. The download program is stored in the analysis device in advance.

A fluid system and an optical system of the particle analyzing apparatus of the present invention are shown in FIG.
In FIG. 1, when the valves 16 and 17 are opened, the particle suspension is sucked from the suction pipette 1 by the pump 18, passes through the sample filter 2, and is drawn into the sample charging line 3 at the top of the flow cell 5. The sample filter 2 removes coarse particle dust in the suspension so that the flow cell 5 having a narrow (narrow) flow path is not clogged. The sample filter 2 also has an effect of loosening coarse agglomerates.

  The particle suspension drawn into the charging line 3 is guided to the flow cell 5 by closing the valves 16 and 17 and operating the syringe 4, and the suspension is discharged from the tip of an internal sample nozzle (not shown). Extruded. At the same time, the sheath liquid is also sent from the sheath liquid bottle 6 through the sheath liquid chamber 7 to the flow cell 5, the particle suspension is surrounded by the sheath liquid, and the suspension is squeezed flatly in terms of fluid dynamics. And is discharged through the waste liquid chamber 14. By periodically irradiating pulse light from the strobe 8 to the suspension flow narrowed in this manner, a still image of particles is captured by the video camera 10 via the objective lens 9.

As a solvent for suspending particles, an optimum solvent may be selected according to particle characteristics (particle size and specific gravity).
Further, in order to reliably narrow the flow of the suspension flatly or finely, it is preferable to change the viscosity or specific gravity of the sheath liquid according to the characteristics of the suspension, for example, according to the viscosity or specific gravity of the solvent. Although not shown in FIG. 1, a plurality of types of sheath liquid bottles may be provided, and a mechanism that can easily switch the type of sheath liquid to be used according to the sample to be measured may be added.

  If the flat surface of the suspension flow is imaged by the video camera 10, a particle image can be captured over the entire imaging area of the video camera 10, and a large number of particles can be imaged by one imaging as shown in FIG. . In addition, since the distance between the center of gravity of the imaged particle and the imaging surface of the video camera 10 can be made almost constant, a focused particle image can always be obtained regardless of the size of the particle.

  FIG. 3 is a block diagram showing a signal processing system of the particle image analyzer. As shown in the figure, the image processing unit 11 includes a binarization unit 11a that converts an image signal from the video camera 10 into binarized data, and an edge trace unit that performs edge tracing of the binarized particle image data. 11b, an analysis unit 11c for analyzing data obtained by edge tracing, a data storage unit 11d for storing image data, processing data, and the like, and a particle image analysis read from a program recording medium by the program reading unit 15 A program storage unit 11e for storing a program is provided. Then, the image processing unit 11 processes the image signal from the video camera 10 according to the processing condition input from the keyboard 13 and displays the processing result on the monitor television 12.

  The procedure of image processing in such a configuration is shown in the flowchart of FIG. An image signal from the video camera 10 is captured by the image processing unit 11, A / D converted, and captured as image data (step S1). Next, background correction for correcting the intensity unevenness (sudding) of the irradiation light with respect to the suspension flow is performed (step S2).

  Specifically, image data obtained by light irradiation when not passing through the particle flow cell 5 is captured in advance before measurement, and the image data is compared with the image data of the actual particle imaging screen. This is a process generally improved as image processing. Next, contour enhancement processing is performed as preprocessing for accurately extracting the contour of the particle image (step S3). Specifically, generally well-known Laplacian enhancement processing is performed.

  Next, when the image data is binarized at an appropriate threshold level, each particle image becomes a binarized image as shown in FIG. 5 (step S4). Next, for each binarized particle image, it is determined whether the edge point is a (contour pixel representing the contour), and in which direction is the edge point adjacent to the edge point of interest Information, that is, a chain code is generated (step S5). Next, edge tracing of the particle image is performed with reference to this chain code, and the area (total number of pixels) St, the orthogonal count number Et, the skew count number Es, and the corner count of each particle image are analyzed as the particle image analysis parameters. The number Cn is obtained (step S6).

  Here, the processing in steps S5 and S6 will be described with reference to FIG. 5. The center points a to n of the contour pixels (edge points) forming the contour of the particle image (hatched portion in FIG. 5) are connected by straight lines. Focusing on the contour pixels sequentially from the point a in the counterclockwise direction (or clockwise direction), when the straight line connecting the current target contour pixel and the next target contour pixel faces in the vertical or horizontal direction, It is regarded as one pixel, and when the straight line connecting the current target contour pixel and the next target contour pixel faces in an oblique direction, the current target contour pixel is regarded as the second pixel, and the number of first and second pixels is counted.

Here, the total number of first pixels is the orthogonal count number Et, and the total number of second pixels is the skew count number Es.
Further, in FIG. 5, when a straight line connecting one contour pixel of interest and two contour pixels adjacent to both sides thereof is bent at the focused contour pixel, the contour pixel is regarded as a bending point, and all the contour pixels Paying attention to each, the number of bending points is counted. The total number of bending points is the corner count number Cn.
In the particle image shown in FIG.
Area St = total number of pixels = 25,
Since the first pixel is a pixel including points c, e, g, h, j, k, l, m, Et = 8,
Since the second pixel is a pixel including points a, b, d, f, i, and n, Es = 6.
Since the bending points are points a, c, d, e, f, g, i, j, and n, Cn = 9.

When the necessary imaging process is completed (step S7), the perimeter length L is first calculated by the following equation based on the analysis parameters obtained for each particle image (step S8).
L = 0.980 * Et + 1.406 * Es-0.091 * Cn ... (1)
(However, one pixel has a unit length of 1.)
Equation (1) is known as Vossepoel's equation.
Next, the area S is calculated by the following equation (step S9).
S = St−0.5L (2)
(However, one pixel has a unit length of 1)
Next, the equivalent circle diameter Rs is calculated by the following equation (step S10).
Rs = a × S ^1/2 × k + b (3)
Here, k is the size of one pixel, and a and b are correction coefficients.
Next, the unevenness degree X is calculated by the following equation (step S11).
X = Cn / L (4)
In addition, since the unevenness degree X of the particle image shown in FIG. 5 is Cn = 9 and L = 15.5,
X = 0.58
It becomes.

  As described above, not only the perimeter length, area, and equivalent circle diameter but also the degree of unevenness can be obtained for each of a large number of particle images, and the particle image can be statistically analyzed using these.

It is principal part structure explanatory drawing of the Example by this invention. It is explanatory drawing of the image by the Example of this invention. It is a block diagram which shows the principal part structure of the Example by this invention. It is a flowchart which shows operation | movement of the Example of this invention. It is explanatory drawing of the particle image in the Example of this invention.

Explanation of symbols

1 Suction Pipette 2 Sample Filter 3 Sample Charging Line 4 Sheath Syringe 5 Flow Cell 6 Sheath Liquid Bottle 7 Sheath Liquid Chamber 8 Strobe 9 Objective Lens 10 Video Camera 14 Waste Liquid Chamber

Claims (12)

  Particle image analysis characterized by obtaining the number of inflection points and the perimeter of the particle contour in the image data obtained by imaging the particle, and obtaining the degree of irregularity of the particle from the number of inflection points and the perimeter Method.   The chain code for tracking the contour pixels forming the particle contour is obtained, and the number of inflection points and the perimeter of the particle contour are obtained using the chain code. Particle image analysis method.   3. The particle image analysis method according to claim 2, wherein a chain code for tracking the pixel center of the contour pixel is obtained.   The particle image analysis method according to any one of claims 1 to 3, wherein the unevenness degree is a ratio of the number of bending points to the perimeter.   A binarization unit that binarizes image data obtained by imaging particles, and an edge trace unit that obtains a chain code that tracks contour pixels forming the contours of the particles of the binarized image data; A particle comprising: an analysis unit that obtains the number of inflection points and the perimeter of the particle using the chain code, and obtains the degree of irregularity of the particles from the number of the inflection points and the perimeter Image analysis device.   6. The particle image analysis apparatus according to claim 5, wherein the edge trace unit obtains a chain code for tracking the pixel center of the contour pixel. The particle image analysis apparatus according to claim 5 or 6, wherein the analysis unit obtains the degree of unevenness from the ratio of the number of bending points and the circumference.   The particle image analysis apparatus according to claim 5, wherein the analysis unit calculates an equivalent circle diameter.   A flow cell that converts a suspension containing particles into a suspension flow, a light irradiation unit that irradiates light to the converted suspension flow, and an imaging unit that images the irradiated particles. The particle image analysis apparatus according to claim 5, wherein the particle image analysis apparatus is a particle image analysis apparatus.   Particle image analysis characterized in that the number of inflection points and the perimeter of the particle contour are obtained from the image data obtained by imaging the particle, and the degree of unevenness of the particle is obtained from the number of inflection points and the perimeter program.   A chain code that tracks the contour pixels that form the contour of the particle is obtained, and the number of inflection points and the perimeter of the contour of the particle are obtained by using this chain code. The particle image analysis program according to claim 10, wherein the degree of unevenness is obtained.   The computer-readable recording medium which recorded the program of Claim 10 or 11.

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