JP6907766B2 - Measuring equipment and measuring system - Google Patents

Description

The present invention relates to a measuring device and a measuring system.

In recent years, paints mixed with a bright material such as aluminum flakes and mica flakes have been known in order to give a high-class feeling to home appliances and the like. The paint having such a structure has an appearance to which the glittering appearance peculiar to the bright material is given.
In such a paint containing a glittering material, in order to evaluate the so-called glittering feeling, a method of measuring the painted surface and quantifying the glittering feeling as a particle characteristic is known (see, for example, Patent Document 1). ).

However, the conventional measurement method does not consider the influence of the color of the painted surface and the lighting conditions, and it is not possible to evaluate the difference in the appearance of glitter depending on the color of the sample, and the actual situation such as sunny / cloudy / evening. Due to changes in the environment, there was a risk that there would be a discrepancy between the evaluation value and the appearance.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a measuring device having a high correlation between appearance and evaluation value in consideration of coating color and lighting conditions.

In order to solve the above-mentioned problems, the measuring device of the present invention has the two-dimensional spectroscopic image based on the two-dimensional spectroscopic image of the object and the spectral distribution and intensity distribution of the illumination irradiating the object. was closed and chromaticity conversion means for converting into chromaticity information, and particle characteristics evaluating means for evaluating the particle properties of the surface of the subject matter on the basis of the chromaticity information the chromaticity converter is derived, the The particle characteristic evaluation means evaluates the particle characteristics by weighting the fluctuation amount of the in-plane chromaticity distribution with the average value of the in-plane chromaticity distribution .

According to the measuring device of the present invention, since the particle characteristics on the surface of the object are evaluated in consideration of the coating color and the lighting conditions, the correlation between the appearance and the evaluation value is high.

It is a figure which shows an example of the whole structure of the measurement system which concerns on embodiment of this invention. It is a block diagram which shows an example of the structure of the measuring apparatus shown in FIG. It is a flow chart which shows an example of the operation of the measuring apparatus which concerns on embodiment of this invention. It is a figure which shows an example of the measurement result of the sample which concerns on embodiment of this invention. It is a figure which shows an example of the whole structure of the measurement system which concerns on 2nd Embodiment of this invention. It is a figure which shows the structure of the sample shown in FIG. It is a figure which shows the state of the orientation of the bright material shown in FIG. It is a figure which shows the modification of the embodiment shown in FIG. It is a figure which shows an example of the functional structure of a measuring device. It is a flow chart which shows an example of the operation of the measuring apparatus which concerns on 2nd Embodiment of this invention. It is a figure which shows an example of the measurement result of the sample which concerns on embodiment of this invention. It is a figure which shows an example of the measurement result of the sample which concerns on embodiment of this invention. It is a figure which shows the modification of the embodiment shown in FIG. It is a figure which shows the modification of the structure shown in FIG. It is a figure which shows an example of the measurement result of the sample which concerns on embodiment of this invention. It is a figure which shows the modification of the structure shown in FIG.

As an example of the embodiment of the present invention, FIG. 1 shows a schematic configuration of a measurement system 200 for evaluating particle characteristics.

The measurement system 200 includes a holder 201 on which the sample P, which is an object whose particle characteristics are to be measured, is placed, a light source 202 for irradiating the sample P with the irradiation light L, and the reflected light L reflected by the sample P. It has an image pickup device or a camera device 203 which is an image pickup unit that receives light and acquires a two-dimensional spectroscopic image.
The measurement system 200 includes a measurement device 100 for quantitatively evaluating the particle characteristics of the surface of the sample P, that is, the glittering appearance peculiar to the bright material, based on the two-dimensional spectroscopic image of the sample P taken by the camera device 203. is doing.
In the following description, for the sake of simplicity, as shown in FIG. 1, the vertical upper direction is set to the + Z direction, and among the planes perpendicular to the Z direction, the Y direction toward the back side of the paper surface and the left and right direction of the paper surface are X. As a direction, it is assumed that the sample P is a plate-shaped sample placed parallel to the XY plane.

As the light source 202, a xenon light source is used in this embodiment, and the illuminance on the surface of the sample P is set to be about 100,000 lux.

The camera device 203 is a hyperspectral camera capable of measuring a measurement wavelength range of 400 nm to 700 nm with a bandwidth of 5 nm.
The camera device 203 adjusts the magnification using a lens so that 1 pixel is 30 μm in the range of 200 × 200 pixels, measures the surface state of the sample P, and captures a two-dimensional spectroscopic image. The camera device 203 is not limited to such a configuration, and may be a multispectral camera or a spectroscopic camera capable of capturing a two-dimensional spectroscopic image in a plurality of wavelength widths.
Further, the two-dimensional spectroscopic image is different from an image such as a photograph using ordinary three primary colors, and shows an image in which the hue in each pixel is recorded as a wavelength component engraved with a predetermined bandwidth. ..

Both the camera device 203 and the light source 202 are rotatably installed so that the angle can be freely changed with respect to the holder 201, and the angle at which the particle characteristics are most emphasized according to the position of the sample P. Can be measured at.

Sample P is a plate-shaped member having a pearl-coated surface on at least the surface on the + Z direction side.
In the present embodiment, the sample P is placed parallel to the XY plane, and as shown in FIG. 1, the measurement is performed with the incident angle of the illumination light L being 25 ° and the installation angle of the camera device 203 being 0 °.
It should be noted that the angle is not limited, and the angle may be changed to take a plurality of shots.
As shown in FIG. 6, the sample P has a base material 300 which is a base layer and a coating layer 301 which is a coating surface formed on the upper surface of the base material 300, and the coating layer 301 is brilliant. Aluminum flakes 302 as a material are scattered. Although aluminum flakes are used here, the structure is not limited to this, and mica flakes or the like may be used, or other metal pieces may be used.
Depending on the position and angle of the aluminum flakes 302, when the sample P is viewed, a so-called “glittering feeling” peculiar to the bright material is generated due to the local metallic luster and the strength of reflection.
In the present embodiment, the degree of such glittering feeling is evaluated as a particle characteristic.

As shown in FIG. 2, the measuring device 100 is derived by a chromaticity conversion unit 10 which is a chromaticity conversion means for converting a two-dimensional spectroscopic image captured by the camera device 203 into chromaticity information, and a chromaticity conversion unit 10. It has a particle property evaluation unit 20 which is a particle property evaluation means for evaluating the particle property of the surface of the sample P based on the chromaticity information.

The chromaticity conversion unit 10 includes a series of programs for converting a two-dimensional spectral image into chromaticity information by a spectral reflectance acquisition step, a tristimulus value conversion step, and a chromaticity acquisition step, which will be described later as shown in FIG. Information processing department.
Similarly, as will be described later, the particle property evaluation unit 20 uses the chromaticity information obtained by the chromaticity conversion unit 10 to acquire a deviation image acquisition step of acquiring a deviation image in the Lab color space, and Fourier the deviation image. It is an information processing unit that executes an evaluation value calculation step of extracting a frequency component by conversion and calculating a particle property evaluation value.
Although the chromaticity conversion unit 10 and the particle characteristic evaluation unit 20 are both information processing units provided in the measuring device 100 in the present embodiment, a personal computer having a program having the above configuration installed is installed. It may be an external device such as.

A method for evaluating the particle characteristics of the sample P will be described using the measuring device 100 having the above configuration.

First, the positional relationship between the light source 202 and the camera device 203 is adjusted so that the irradiation light L emitted from the light source 202 is incident on the camera device 203, and the initial state is set (step S101).
In the initial state, first, a two-dimensional spectroscopic image is taken using a standard sample for calibration (step S102). At this time, it is desirable to adjust the exposure time of the camera device 203 so that there are no saturated pixels and record the exposure time.
In this embodiment, a white reference plate having a reflectance of 100% and a reflection characteristic close to that of completely diffused radiation is used as a standard sample.

Next, the sample P is placed on the holder 201, and a two-dimensional spectroscopic image is taken in the same manner as in step S102 (step S103). Such step S103 is an imaging step of acquiring a two-dimensional spectroscopic image of the sample P as an object. At this time, the exposure time of the camera device 203 is adjusted and recorded so that there are no saturated pixels, similarly to the exposure time recorded in step S102.

The chromaticity conversion unit 10 divides each pixel / wavelength of the two-dimensional spectroscopic image obtained in step S103 by each pixel / wavelength of the two-dimensional spectroscopic image of the standard sample obtained in step S102, and divides the sample P. The two-dimensional spectral reflectance of (step S104) is calculated.
When the exposure time differs between when the sample P is photographed and when the standard sample is photographed, it is desirable to multiply the ratio of the exposure times by the measured value of the sample P to correct the difference in the exposure time.

The user sets an arbitrary lighting condition for which he / she wants to know the particle characteristics of the sample P (step S105).
In this embodiment, two patterns of illumination conditions, A state (spectral distribution using a D50 light source) and B state (spectral distribution using a standard light source), which will be described later, are set.
The chromaticity conversion unit 10 calculates the tristimulus value XYZ in each pixel by the two-dimensional spectral reflectance of the sample P obtained in step S104, the spectral distribution set in step S105, and the color matching function.
The two-dimensional spectral reflectance of the sample P obtained in step S104 indicates the wavelength distribution of the reflected light L'reflected when the sample P is exposed to light.
The spectral distribution set in step S105 shows the wavelength distribution of the irradiation light L applied to the sample P.
Therefore, by multiplying the two-dimensional spectral reflectance of the sample P and the spectral distribution, what kind of wavelength distribution the light incident on the human eye from the sample P shows is simulated.

Here, the color matching function is a function that expresses the difference in sensitivity of the sensory tissues corresponding to R, G, and B of the human eye. That is, what kind of tristimulus value XYZ is used in the human eye by using the wavelength of light incident on the human eye and the difference in sensitivity of the sensory tissue corresponding to R, GB, and B of the human eye. It is a numerical value that expresses whether it can be seen as a color.
In the present embodiment, the tristimulus values XYZ represented by the formulas (1) to (3) in the formula 1 are treated as a part of the chromaticity information that quantitatively expresses the color.
It is known that a person's color sensation changes not only due to individual differences but also when the viewing angle (size of an object) changes. Therefore, in the present embodiment, the calculation is performed using the color matching function corresponding to the 10 ° field of view.

In Equation 1, S (λ): spectral distribution of illumination, x (λ), y (λ), z (λ): color matching function, R (λ): spectral reflectance, k: coefficient.
Further, the coefficient k is expressed by the equation (4) of the mathematical formula 2 in the conventional tristimulus value conversion.

By the way, when the conventional coefficient k is used, if the three stimulus values differ depending on the intensity of the irradiation light L, it is necessary to specify the intensity of the light source, which limits the measurement conditions. Therefore, conventionally, the intensity of the irradiation light L is standardized by the coefficient k in order to express the appearance regardless of the intensity of the irradiation light L.
That is, no matter what function S (λ) is, the tristimulus value XYZ does not depend on | S (λ) |.

However, according to the study of the inventor, it has been found that when the particle property evaluation unit 20 evaluates the particle characteristics, the actual appearance differs greatly depending on the intensity of the irradiation light L, as will be described later.
Therefore, in the present embodiment, as shown in Equation 3 as Equation (5), the tristimulus value XYZ is calculated as a coefficient k'including the illumination intensity coefficient α (step S106).

In other words, the illumination intensity coefficient α determines how many times the illumination intensity should be set based on the illumination intensity when Y becomes 100 out of the three stimulation values of the standard sample. equal.
For example, assuming illumination with an intensity of 50% of the light of the halogen lamp of the reference light source 202, when it is desired to evaluate the particle characteristics, the tristimulus values are calculated with α = 0.5.
As described above, if the intensity coefficient α is used for the calculation of the tristimulus value XYZ, the tristimulus value XYZ depends on | S (λ) |.

Next, the chromaticity conversion unit 10 converts the tristimulus values XYZ into L *, a *, and b * (step S107).
The conversion formula at this time is expressed as shown in the formula 4 defined by the International Commission on Illumination (CIE) using, for example, the tristimulus values Xn, Yn, and Zn on the perfect diffuse reflection surface.

In Equation 4, Xn = 96.42, Yn = 100, Zn = 82.49.
As shown in step S107, the chromaticity conversion unit 10 calculates each component of L *, a *, and b * in the Lab color system from the tristimulus values XYZ as chromaticity information.
Step S107 is a chromaticity conversion step in which two-dimensional spectroscopy converts an image into chromaticity information based on the two-dimensional spectroscopic image and the spectral distribution and intensity distribution of the illumination light L irradiating the sample P. ..

Subsequently, a method of calculating the particle quality evaluation value will be described.
First, the particle nature evaluation unit 20 calculates the average value of the L * images among the images of the L *, a *, and b * components in the Lab color system calculated in step S107 (step S201).
The particle nature evaluation unit 20 subtracts the average value from the L * value in each pixel of the L * image calculated in step S201 to acquire the L deviation image (step S202).
The L deviation image is an image showing the amount of fluctuation of how much each pixel deviates from the average of the entire L * image, in other words, the deviation Δ. The deviation Δ of L takes a uniformly low value because the average value rises in a sample such as a metal that reflects as a whole, and a small part that has little influence on the average value is locally particularly strongly reflected. In the so-called glittering state, a large value is taken in the portion of the pixel that appears to shine.
That is, the pixels whose reflection is locally strengthened are perceived by the human eye as a glittering feeling and a grainy feeling.

The particle nature evaluation unit 20 Fourier transforms the L deviation image acquired in step S202 with respect to the deviation Δ in all the pixels. After the Fourier transform, the amplitude is averaged at each frequency to obtain a one-dimensional frequency characteristic (step S203).
The amplitude here is obtained by the square root of the intensity after the Fourier transform. The frequency is determined by the calculated image size (200 × 200pixel) and the measurement resolution (1pixel = 30 μm).

The particle nature evaluation unit 20 weights the Fourier transform result of the deviation Δ obtained in step S203 by the “visual spatial frequency characteristic (VTF) with respect to the observation distance” (step S204). In this embodiment, the function shown in Equation 5 is used as the spatial frequency characteristic of vision.
The configuration is not limited to this, and as the spatial frequency characteristic of vision, a function related to other visual characteristics already known may be used.

Here, the unit of u is [cycle / degree]. By converting to Cycle / mm according to the observation distance of the sample P, it is possible to evaluate the grain feeling near or far by multiplying the one-dimensional frequency characteristic obtained in step S203. In this embodiment, the observation distance is 350 mm.

The significance of such weighting will be described.
It is generally known that the human eye has a visual characteristic that the closer the object is to the object, the higher the resolution (easy to see even the finer parts), and the lower the resolution when looking at a distant object (the finer parts are crushed and hard to see) ( For example, see Non-Patent Document 1 and the like).
At this time, since the graininess is obtained by visually recognizing "pixels whose reflection becomes stronger locally", even minute pixels are accurately counted when observed from a close location. When observing from a distant place, it can be said that only pixels having a certain size or larger are recognized.
Therefore, in the present embodiment, from the Fourier transform results for all the pixels of the L deviation image acquired in step S203 in step S204, the influence on the evaluation value of the pixel size that is difficult to recognize according to the observation distance is reduced. Is being processed.
The step S204 is a weighting step for calculating a value obtained by weighting the fluctuation amount with the visual frequency characteristic.

The amplitude values of the respective frequencies obtained in this way are integrated to obtain the particle quality evaluation value (step S205). That is, step S205 is a particle characteristic evaluation step for evaluating the particle characteristics on the surface of the sample P from the chromaticity information. The particle quality evaluation value corresponds to the fact that "pixels whose reflection is locally strengthened" are weighted according to the ease / difficulty of recognition according to the observation distance and counted. That is, as for the particle quality evaluation value, the larger the value, the stronger the particle feeling (appearing as glittering), and the smaller the particle property evaluation value, the weaker the particle feeling.

In the present embodiment, only the deviation image of L in the Lab color space has been described. However, depending on the coloring of the particles and the hue of the sample P, a * and b * are similarly described in steps S201 to S205. Perform the operation of.

FIG. 4 shows an example in which nine types of white pearl samples of the primary color sample book manufactured by ISAMU were measured using the measuring device of the present embodiment in the order of particle roughness described in the sample book.
The one shown by A in FIG. 4 assumes the case where the sample P is observed under the sunlight at noon using a light source having a specific wavelength showing the distribution of daylight. Similarly, in FIG. 4, the shaded B indicates that the amount of the irradiation light L of the standard light source that emits uniform light at all wavelengths is reduced to 20%, and the sample P is sampled in the evening when the sunlight becomes dark. It is supposed to be when observed.

As is clear from FIG. 4, neither the A state nor the B state is reversed from the order written in the sample book, but the particle quality evaluation values are P1 to P4 for each sample P1 to P9 and P1 to P4 in the A state. There is a difference of 0.1 or more between them, but in the B state, it is within the range of about 0.05 between P1 and P4.
Further, it can be seen that the particle quality evaluation value is suppressed to about half as a whole in the B state as compared with the A state.
That is, it is shown that in a state where the sunlight is dark as in the B state, the difference in the graininess of P1 to P4 is small, and the graininess such as the glittering feeling is weakened.

In this way, since the particle quality evaluation value is greatly affected by the intensity of illumination, the chromaticity conversion unit 10 uses the intensity of the illumination light L in the conversion formula when converting the spectral reflectance into the tristimulus value XYZ. The intensity coefficient α that depends on is added.
With this configuration, the particle characteristics on the surface of the object are evaluated in consideration of the lighting conditions, so that the correlation between the appearance and the evaluation value is high.

In the present embodiment, the measuring device 100 converts the two-dimensional spectroscopic image into chromaticity information based on the two-dimensional spectroscopic image of the sample P and the spectral distribution and intensity distribution of the light source 202 irradiating the sample P. It has a chromaticity conversion unit 10 and a particle property evaluation unit 20 that evaluates the particle characteristics of the surface of the sample P based on the chromaticity information derived by the chromaticity conversion unit 10.
With this configuration, the particle characteristics on the surface of the object are evaluated in consideration of the lighting conditions, so that the correlation between the appearance and the evaluation value is high.

In the present embodiment, the chromaticity information includes a deviation Δ which is a fluctuation amount of L *, a *, and b * in the Lab color system.
With this configuration, since the deviation Δ indicates a pixel whose reflection is locally strong, it is perceived by the human eye as a glittering feeling and a grainy feeling.

In the present embodiment, the deviation Δ is a value indicating the frequency characteristic of the deviation image when the difference is taken from each average value of L *, a *, and b * in the Lab color system.
With such a configuration, the local reflection can be evaluated in a state closer to the actual appearance, and the correlation between the appearance and the evaluation value is high.

Further, in the present embodiment, the particle nature evaluation unit 20 evaluates the particle characteristics based on the value obtained by weighting the deviation Δ with the visual spatial frequency characteristics.
With this configuration, "pixels whose reflection is locally strong" are weighted according to the ease / difficulty of recognition according to the observation distance. Therefore, it is possible to reflect the appearance in consideration of the observation distance in the evaluation value.

Further, in the present embodiment, the measurement system 200 includes a measurement device 100 including a chromaticity conversion unit 10 and a particle quality evaluation unit 20, a light source 202 that irradiates the sample P with the irradiation light L, and a sample P surface of the irradiation light L. It has a camera device 203 for acquiring a two-dimensional spectroscopic image from the reflected light L'in the above.
With this configuration, the particle characteristics on the surface of the object are evaluated in consideration of the lighting conditions, so that the correlation between the appearance and the evaluation value is high.

Further, in the particle characteristic evaluation method used in the present embodiment, a two-dimensional spectroscopic image is obtained based on the acquired two-dimensional spectroscopic image of the sample P and the spectral distribution and intensity distribution of the irradiation light L irradiating the sample P. It has a chromaticity conversion step S107 for converting into chromaticity information, and a particle characteristic evaluation step S205 for evaluating the particle characteristics on the surface of the sample P from the chromaticity information.
With this configuration, the particle characteristics on the surface of the object are evaluated in consideration of the lighting conditions, so that the correlation between the appearance and the evaluation value is high.

Next, as a second embodiment of the present invention, the measurement system 200b as shown in FIG. 5 will be described.
In the second embodiment, the description of the same configuration as that of the first embodiment will be omitted as appropriate.
The measurement system 200b is an imaging device that captures a two-dimensional color image by receiving two light sources 202a and 202b for irradiating the sample P with the irradiation light L and the reflected light L'irradiated and reflected by the sample P. It has a camera device 203b as an imaging unit, and a measuring device 100b for evaluating particle characteristics from an image acquired by the camera device 203b.

Both the light source 202a and the light source 202b are white LED light sources, and are arranged so that the illumination angles with respect to the sample P, that is, the incident angles of the irradiation lights La and Lb are different from each other.
In this embodiment, in particular, the illumination angle of the light source 202a is positioned so that the inclination angle is −10 ° with respect to the specular reflection direction of the camera device 203b. Further, the illumination angle of the light source 202b is arranged so as to have an inclination angle of + 45 ° with respect to the specular reflection direction.
That is, in the present embodiment, at least one of the plurality of light sources 202a and 202b is arranged between the inclination angles of −25 ° to + 25 ° with respect to the specular reflection direction.

This point will be described in more detail. As shown in FIG. 6, the sample P has a coating layer 301 and a base material 300, and aluminum flakes 302 are contained in the coating layer 301 in the horizontal direction of the coating layer 301 as shown in FIG. It is scattered with various orientation angles θ. Due to the orientation angle θ, when the irradiation lights La and Lb are applied to the aluminum flakes 302 inside the coating layer 301, reflection is generated in a direction different from specular reflection, and a glittering feeling appears.
Further, in coating the coating layer 301, it is known that the aluminum flakes 302 are difficult to have an extremely large orientation angle θ, and generally, it is known to have an orientation angle θ in the range of ± 25 °. ing.
Therefore, by arranging at least one of the plurality of light sources 202a and 202b between the inclination angles of -25 ° to + 25 ° with respect to the specular reflection direction, a highly grainy reflected light L'near the specular reflection can be obtained. Therefore, it becomes easy to evaluate the particle characteristics on the surface of the object in consideration of the illumination conditions.

Further, of the plurality of light sources 202a and 202b, the other one (light source 202b in this embodiment) is arranged so that the inclination angle is + 45 ° with respect to the specular reflection direction.
At this time, since the reflected light of the light source 202b is in a diffused condition, the reflected light L'with a strong reflection intensity near the normal reflection condition and the reflected light L'with a weak reflection intensity near the diffused condition are incident on the camera device 203b. do.
With this configuration, by irradiating the sample P with light under a plurality of different lighting conditions, the camera device 203b acquires a first image and a second image which are two-dimensional color images corresponding to the plurality of different lighting conditions. do.
With such a configuration, the particle characteristics on the surface of the sample P can be evaluated based on the actual human visual sensation and the lighting conditions.

Further, in the present embodiment, the illumination angle is arranged so as to include at least an illumination angle in the range of an inclination angle of −25 ° to + 25 ° with respect to the specular reflection direction, but the present invention is not limited to this configuration. For example, as shown as a modification in FIG. 16, the arrangement of the plurality of light sources 202a and 202b may be changed in various ways.
Further, as shown in FIG. 16, if the camera device 203b is arranged directly above the sample P so that the inclination angle is 0 °, the camera device 203b is in focus on the entire sample P regardless of the lighting conditions. , The acquisition of the image becomes easier.

In this embodiment, two light sources 202a and 202b are used, but as shown in FIG. 8, a reflective dome illumination 205 may be provided above the sample P.
With such a configuration, the light source 202a is incident on the camera device 203 as reflected light L'with strong reflection intensity in the vicinity of normal reflection, and the irradiation light Lb from the light source 202b is reflected on the inner wall surface of the dome illumination 205. The sample P is irradiated from the entire surface as diffused light, and a specific diffused angle reaches the camera device 203b.
In other words, even in the modified example as shown in FIG. 8, the reflected light L'from the light source 202a reaches the camera device 203 with a light intensity close to that of the normal reflected light, as shown in FIG. The reflected light L'from the light source 202b reaches the camera device 203b as the reflected light L'with a weak reflection intensity near the diffusion condition.

The camera device 203b is an RGB color camera, and the magnification is adjusted by using a lens so that 1pixel = 30 μm, the surface state of the sample P is measured, and an RGB image which is a two-dimensional color image is taken.
At this time, there is a concern that the light intensity of the reflected light L'that reaches the camera device 203b is significantly different between the light source 202a arranged near the specular reflection and the light source 202b arranged under the diffusion condition.

Therefore, when the difference in light intensity is large, the amount of reflected light may not fit within the dynamic range of the camera device 203b.
In such a case, the measurement system 200b may be provided with light intensity adjusting means. Examples of the light intensity adjusting means include adjusting the light intensity of the light sources 202a and 202b, attaching an ND filter to the incident side of the camera device 203b, and adjusting the exposure time of the camera device 203b to adjust the light intensity. The configuration to drop is mentioned.

The measuring device 100b has a function as a particle characteristic evaluation means having substantially the same configuration as the measuring device 100 described in the first embodiment.
Further, as shown in FIG. 9, the measuring device 100b includes a chromaticity conversion unit 10 for acquiring the in-plane chromaticity distribution in the coating layer 301 of the sample P from the two-dimensional image taken by the camera device 203b, and the in-plane chromaticity distribution. It has a particle characteristic evaluation unit 20 as a particle characteristic evaluation means for calculating a particle characteristic evaluation value for evaluating the particle characteristics based on the amount of fluctuation of the above.

The chromaticity conversion unit 10 has the same function as that of the first embodiment, but is different in the second embodiment in that the image used is a two-dimensional color image.
As shown in FIG. 10, the chromaticity conversion unit 10 has an image acquisition step S301 for acquiring an RGB image which is a two-dimensional color image and a tristimulus value conversion step S302 for converting an RGB image into an XYZ image which is a tristimulus value. An information processing unit provided with a series of programs for converting a two-dimensional color image into chromaticity information by means of chromaticity acquisition step S303 for converting an XYZ image into an L * a * b * space which is a uniform color space. Is.
That is, the chromaticity conversion unit 10 has a function as a chromaticity distribution acquisition means for acquiring the in-plane chromaticity distribution of the sample P under at least two or more lighting conditions or light receiving conditions.

Similarly, the particle nature evaluation unit 20 calculates the particle nature evaluation value in the Fourier transform step S304 that Fourier transforms the L * deviation image, the step S305 that weights by visual characteristics, and the step S306 that weights by color. The information processing unit executes the evaluation value calculation step S307.
Although the chromaticity conversion unit 10 and the particle characteristic evaluation unit 20 are both information processing units provided in the measuring device 100 in the present embodiment, a personal computer having a program having the above configuration installed is installed. It may be an external device such as.

A method of calculating the particle quality evaluation value using such a configuration will be described.
First, the camera device 203b takes a first image which is a two-dimensional color image with only the light source 202a turned on. Next, with only the light source 202b turned on, the second image is similarly taken using the camera device 203b.
Both the first image and the second image include a photograph of at least a part of the surface of the sample P so that the photographed range coincides with the first image and the second image. Be photographed. For example, in the present embodiment, it is a shooting range of a square of 512 × 512 pixel.
At this time, the first image and the second image captured by the camera device 203b are two RGB images having different irradiation conditions of the light source (step S301).

The chromaticity conversion unit 10 converts each of the first image and the second image from an RGB image to an XYZ image having three stimulus values (step S302).
Generally, the RGB → XYZ conversion formula in sRGB (D65) may be used.
Next, the XYZ image is converted into a Lab image using the mathematical formula 4 defined by the International Commission on Illumination (CIE) (step S303).

In the present embodiment, the RGB image is acquired by using the RGB camera as the camera device 203b, but the XYZ camera may be used. In that case, the RGB → XYZ conversion in step S302 can be omitted.

Next, the chromaticity conversion unit 10 calculates the average value L * ave of L * in the image plane of the L * image, and the average value from the L * value in each pixel of the L * image corresponding to the first image. The deviation image of L * is calculated by subtracting L * ave.
The deviation image of L * referred to here represents the amount of fluctuation of how much each pixel deviates from the average of the entire L * image.
That is, in the imaging region, the deviation becomes large only for the locally glittering pixels, and the strength of the local deviation is perceived by the human eye as the strength of the particle feeling.

Next, the particle characteristic evaluation unit 20 performs a two-dimensional Fourier transform on the deviation image (step S304). After the Fourier transform, the amplitude is averaged at each frequency to obtain a one-dimensional frequency characteristic.

At this time, since the graininess is obtained by visually recognizing "pixels whose reflection is locally strengthened", the amplitude values of the respective frequencies obtained in step S304 are integrated to obtain the _GL value. Step S304 is a particle characteristic evaluation step for evaluating the particle characteristics on the surface of the sample P from the chromaticity information.

Such a _GL value corresponds to the counting of pixels in which the reflection is locally strong on the surface of the sample P, but the strength of the graininess felt by a person is as described in step S205 of the first embodiment. In addition, it varies depending on the visual characteristics.
Therefore, also in the present embodiment, by weighting by the visual characteristics as shown in step S305, the particle characteristic evaluation value S, which will be described later, has a deeper correlation with the particle feeling felt by humans. Note that such weighting is omitted because it overlaps with the description in step S204.

By the way, the strength of the graininess is affected not only by the visual characteristics but also by the color, that is, the appearance of the sample P is different depending on whether it is colorless such as silver or colored. Are known.
Specifically, research by the inventors has revealed that the whiter and brighter the sample P, the harder it is to perceive the graininess, and the darker and darker the sample P, the easier it is to perceive the graininess. ing.
That is, in the weighting shown in step S306, the particle characteristic evaluation unit 20 has a lower particle characteristic evaluation value S as the average brightness of the in-plane chromaticity distribution is higher or the average saturation of the in-plane chromaticity distribution is lower. It is desirable to perform weighting so as to be.

Specifically, the whiteness W is calculated from each in-plane average value of the measured L * a * b * image using the mathematical formula 6, and the particle characteristic evaluation value S is calculated according to the whiteness W. ..

The whiteness W increases as the contribution of L * in the image plane increases, and decreases as the contribution of a * and b * in the image plane increases. By correcting the whiteness W as shown in Equation 7, the particle characteristic evaluation value S becomes an index having a deeper correlation with the human grain feeling. That is, in such a configuration, the "average value of the in-plane chromaticity distribution" can be said to be the average value of the in-plane whiteness.

Note that p1, p2, and p3 are integration coefficients, which are parameters determined by nonlinear regression analysis based on the sensory evaluation points, respectively.
Further, in the present embodiment, since the deviation image of L * _{is used, the particle characteristic evaluation value S is calculated using the GL} value, but when the deviation images of a * and b * are used together. It is desirable to modify Equation 7 as in Equation 8 and handle it.

In this way, weighting by visual characteristics and color is performed (step S305) (step S306), and the particle characteristic evaluation value S is calculated (step S307).

As described above, in the present embodiment, the particle characteristic evaluation value S is calculated for each of the first image taken with the light source 202a turned on and the second image taken with the light source 202b turned on.
Here, assuming that the particle characteristic evaluation value S1 of the first image and the particle characteristic evaluation value S2 of the second image are used, the particle characteristic evaluation value S1 represents the glittering feeling of the particles when observed at the highlight, and the particle characteristic evaluation value. It can be said that S2 is an index showing the glittering feeling of the particles when observed in a short time.

FIG. 11 shows the respective particle characteristic evaluation values S1 and the particle characteristic evaluation value S2 combined to clarify the correlation with the sensory evaluation points. Here, the sensory evaluation points are defined by presenting a color sample book manufactured by ISAMU to the observer, and having 15 observers observe the color sample book by highlighting, shaving, and observing at an observation distance of 350 mm under each irradiation condition. This is the average score of each sample when the glittering feeling of each sample was evaluated on a 10-point scale.
As is clear from FIG. 11, the particle characteristic evaluation value S1 and the particle characteristic evaluation value S2 are clearly correlated with the evaluation of the glittering feeling observed by the observer, and the contribution rate to the sensory evaluation point is high. You can see that.

It should be noted that the particle property evaluation value S1 and the particle property evaluation value S2 can each evaluate the particle property when viewed from the corresponding angles, but in reality, the observer can evaluate the particle properties at various angles and various angles. In order to observe in an environment, it is desirable that the particle characteristic evaluation value is also quantified by the overall strength and weakness of the particle feeling.
Therefore, in the present embodiment, the particle characteristic evaluation unit 20 evaluates the glitter degree Sk and the glare degree Sg using the equations 9 and 10.

The number 9 indicates that the stronger the graininess when viewed at the highlight and the weaker the graininess when viewed at the watermark, the more the observer feels that the painted surface is shining. The number tens indicate that the observer feels that the painted surface is glaring when the graininess is strong in both the highlight and the watermark.

Each of the glitter degree Sk and the glare degree Sg shown in the equations 9 and 10 has a correlation with the sensory evaluation points as shown in FIG.
With this configuration, the particle characteristics on the surface of the object are evaluated in consideration of the lighting conditions, so that the correlation between the appearance and the evaluation value is high.
Further, since the particle characteristics of the surface of the object are evaluated using the highlight particle characteristic evaluation value S1 and the watermark particle characteristic evaluation value S2 using the measurement image of the same location of the sample P, the measurement is performed. The variation becomes smaller.

In the present embodiment, the illumination color is white, but various illumination colors may be used according to a specific wavelength such as evaluation in the evening.

Further, as shown in FIG. 13, the measurement system 200c may have a moving portion 204 which is a rotation mechanism capable of moving the light source 202 to two points having different irradiation angle conditions, a position a, and a position b.
According to this configuration, the first image is taken with the light source 202 turned on at the position a, and the second image is taken with the light source 202 turned on at the position b.
The method of calculating the particle characteristic evaluation value using the first image and the second image is the same as that of the second embodiment described above, and thus the description thereof will be omitted.

Alternatively, as shown in FIG. 14, the measurement system 200d may be used for taking pictures using a plurality of camera devices 203a and 203b.
In the case of such an embodiment, it is desirable to arrange at least one camera device 203a in the vicinity of the specular reflection direction of the light source 202. The term "near the specular reflection direction" here may be appropriately set according to the orientation of the aluminum flakes 302 of the sample P, but generally indicates a range of -25 ° to + 25 ° with respect to the specular reflection direction. ..
According to such a configuration, when the cost of the camera device 203 is lower than that of the light source 202, it contributes to cost reduction.

Further, in the present embodiment, the camera devices 203a and 203b are connected to the measuring device 100b by wire, respectively, but the present invention is not limited to such a configuration, and a wireless connection may be used.

In addition, a third embodiment of the present invention will be described.
In the third embodiment, the measurement system 200 includes a holder 201 on which the sample P, which is an object whose particle characteristics are to be measured, is placed, a light source 202 for irradiating the sample P with the irradiation light L, and the sample P. It has an image pickup device or a camera device 203 which is an image pickup unit, which receives the reflected light L'reflected by the light source and acquires a two-dimensional spectroscopic image.
In the third embodiment, the description of the portion having the same configuration as that of the first embodiment shown in FIG. 1 will be omitted.
In the third embodiment, in addition to the operations performed in steps S101 to S205 in the first embodiment, the formulas 9 and 10 shown in the second embodiment are used to obtain the glitter degree Sk and the glare degree Sg. It is different in that it evaluates.

That is, in the third embodiment, the measuring device 100 includes a chromaticity conversion unit 10 which is a chromaticity distribution acquisition means for acquiring the in-plane chromaticity distribution of the sample P under at least two or more illumination conditions or light receiving conditions. The particle characteristic evaluation means 20 for calculating the particle characteristic evaluation value for evaluating the particle characteristics based on the amount of fluctuation of the in-plane chromaticity distribution is provided.
With this configuration, the particle characteristics on the surface of the object are evaluated in consideration of the lighting conditions, so that the correlation between the appearance and the evaluation value is high.

Further, in the third embodiment, the particle characteristics of the sample P are evaluated using at least two or more particle characteristic evaluation values Sk and Sg calculated by using the particle characteristic evaluation means 20.
With this configuration, the particle characteristics on the surface of the object are evaluated in consideration of the illumination conditions, so that the correlation between the appearance and the evaluation value is higher.

FIG. 15 shows an example in which the glitter degree Sk was evaluated for the white pearl sample of the color sample book manufactured by ISAMU, which was also used in the first embodiment.
In FIG. 15, similarly to FIG. 4, the A state is set as the illumination condition of the D50 that imitates the daytime light, the light amount of the standard light source is reduced to 20%, and the state that imitates the dusk light is set as the B state. displayed.
From FIG. 15, when comparing the A state and the B state, it can be seen that the glitter degree Sk can be suppressed to about half.
As already described, Equation 6 is an index indicating a state in which the graininess is strong when viewed at the highlight and the graininess is weak when viewed at the watermark. That is, it is shown that the observer cannot strongly recognize the difference between the highlight and the watermark in the B state imitating the dusk, and it becomes difficult to see the difference in the glittering feeling Sk.
As described above, by evaluating the particle characteristics using at least two or more particle characteristic evaluation values, the measuring device 100 can perform an evaluation having a higher correlation with the actual human visual sensation. ..

Although the preferred embodiment of the present invention has been described above, the present invention is not limited to such a specific embodiment, and unless otherwise specified in the above description, the present invention described in the claims. Various modifications and changes are possible within the scope of the above.

For example, in the present embodiment, the case where the measurement system has an image pickup device and the two-dimensional spectroscopic image is captured by the image pickup device has been described, but the two-dimensional spectroscopic image may be transmitted from the outside of the measurement system. ..
Further, in the present embodiment, the case where the particle nature is evaluated from one two-dimensional spectroscopic image has been described, but a plurality of two-dimensional spectroscopic images may be used.

Further, the measurement system 200 shown in the first embodiment has various conditions such as various illumination angles, spectral distributions, and illumination intensities as shown in the second embodiment, and a light receiving angle due to a change in the position of the imaging device. A configuration for changing the conditions of the above may be added.

The effects described in the embodiments of the present invention merely list the most preferable effects arising from the present invention, and the effects according to the present invention are limited to those described in the embodiments of the present invention. is not it.

10 Color conversion means (color conversion unit)
20 Particle property evaluation means (particle property evaluation unit)
100 Measuring device 200 Measuring system 201 Holder 202 Light source (light source)
203 Imaging device (camera device)
302 Bright material L Lighting (irradiation light)
L'Reflected light P Object (sample)
S107 Chromaticity conversion step S205 Particle characteristic evaluation step W Whiteness XYZ 3 Stimulation value Δ Deviation (variation amount) (chromaticity information) (variation amount of in-plane chromaticity distribution)
α coefficient (strength coefficient)

Japanese Patent No. 5257170 Japanese Unexamined Patent Publication No. 2006-208333

R. P. Dooley, R.M. Shaw: Noise Perception in Xerography, J. et al. Apple. Photogr. Eng. , 5, 4 (1979), pp. 190-196.

Claims (20)

In a measuring device that evaluates the particle characteristics of a painted surface containing a bright material
A chromaticity distribution acquisition means for acquiring an in-plane chromaticity distribution of an object under at least two or more lighting conditions or light receiving conditions.
Based on the amount of change of the in-plane chromaticity distribution, possess a particle characterization means for calculating the particle characterization value for evaluating the particle properties, a,
The particle characteristic evaluation means has a flatness of the in-plane chromaticity distribution with respect to the fluctuation amount of the in-plane chromaticity distribution.
A measuring device characterized in that the particle characteristics are evaluated by weighting with an average value. In the measuring device according to claim 1,
A measuring device characterized in that the particle characteristics of the object are evaluated using at least two or more particle characteristic evaluation values calculated by using the particle characteristic evaluation means. In the measuring device according to claim 1 or 2.
In the weighting of the average value, the particle characteristic evaluation means has a lower particle characteristic evaluation value as the average brightness of the in-plane chromaticity distribution is higher or the average saturation of the in-plane chromaticity distribution is lower. A measuring device characterized in that weighting is performed as described above. In the measuring device according to any one of claims 1 to 3.
A measuring device characterized in that the average value of the in-plane chromaticity distribution is the average value of the in-plane whiteness. In the measuring device according to any one of claims 1 to 4.
The lighting condition is a measuring device characterized by being a lighting method. In the measuring device according to claim 5,
The illumination method is a measuring device characterized in that it is a difference between parallel light and diffused light. In the measuring device according to any one of claims 1 to 6.
The lighting condition is a measuring device characterized by being a lighting angle. In the measuring device according to claim 7.
The chromaticity distribution acquisition means acquires two or more in-plane chromaticity distributions having different illumination angles, and obtains the in-plane chromaticity distribution.
A measuring device characterized in that the illumination angles differ from each other by 25 ° or more. In the measuring device according to any one of claims 1 to 8.
The illumination condition is a measuring device characterized by having a spectral distribution or an illumination color. In the measuring device according to any one of claims 1 to 9.
The lighting condition is a measuring device characterized in that it is a lighting intensity. In the measuring device according to any one of claims 1 to 10.
The light receiving condition is a measuring device characterized by a light receiving angle. In the measuring device according to any one of claims 1 to 11.
The in-plane chromaticity distribution is a measuring device including the amount of fluctuation of L *, a *, and b * in the Lab color system. In the measuring device according to claim 12,
The measuring device characterized in that the fluctuation amount of the in-plane chromaticity distribution is a value indicating the frequency characteristics of L *, a *, and b * in the Lab color system. In the measuring device according to any one of claims 1 to 13.
A measuring device characterized in that a two-dimensional color image of the painted surface is used for acquiring the fluctuation amount of the in-plane chromaticity distribution. In the measuring device according to any one of claims 1 to 13.
A measuring device characterized in that a two-dimensional spectroscopic image of the painted surface is used for acquiring the fluctuation amount of the in-plane chromaticity distribution. In the measuring device according to claim 15,
It has an illumination that illuminates the object and
A measuring device comprising the two-dimensional spectroscopic image, a chromaticity conversion means for converting the two-dimensional spectroscopic image into chromaticity information based on the spectral distribution of the illumination and the intensity of the illumination. In the measuring device according to claim 16,
The chromaticity conversion means is a measuring device characterized in that a coefficient depending on the intensity of the illumination is added to a conversion formula for converting the spectral reflectance into three stimulus values. In the measuring device according to any one of claims 1 to 17.
The particle characteristic evaluation means is a measuring device for evaluating the particle characteristics based on a value obtained by weighting the fluctuation amount with a visual spatial frequency characteristic. The measuring device according to any one of claims 1 to 18 .
A light source unit that irradiates the object with light,
An imaging unit that acquires an image from the reflected light of the light in the object,
The measurement system is characterized in that the exposure time or the illumination intensity of the imaging unit is changed according to the illumination angle or the illumination method of the light source unit. The measuring device according to any one of claims 1 to 18.
At least two light source units that irradiate the object with light from different angles,
An imaging unit that acquires an image from the reflected light of the light in the object,
Have,
When viewed from the imaging unit, at least one of the light source units is within a range of ± 25 ° from the position where the specularly reflected light of the light emitted from the light source unit to the object is incident on the imaging unit. Placed in
A measurement system in which another light source unit is arranged outside the above range.

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