JPH09164127A - Method for evaluating light transmissivity of skin and apparatus therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To objectively evaluate the light transmission of a film of every kind such as a cosmetics coating film of foundation or the like or the epidermis of the skin itself. SOLUTION: Light is projected on a specimen A to be tested having a film on the surface thereof and another specimen A to be tested having no film on the surface thereof from a light source 2 through a first polarizing filter 1a, and the reflected light thereof is received by a light receiving means 3 through a second polarizing filter 2 of which the polarizing direction is different from that of the first polarizing filter. The power spectrum density of the received light is calculated and the parameter T related to the light transmissivity of the film or the parameter σ related to the light diffusibility of the film is calculated on the basis of both power spectrum densities and the light transmissivity of the film is evaluated on the basis of the numerical values of these parameters.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for evaluating the light transmittance of various coatings such as a cosmetic coating on the skin or a coating of the skin itself such as the stratum corneum or the epidermis, and an apparatus therefor. .

[0002]

2. Description of the Related Art In order to apply a cosmetic such as foundation to the skin to obtain a desired skin, the correspondence between the texture of the skin (what the skin looks like to an observer) and the physical characteristics of the skin It is effective to analyze the relationship and the correspondence between the type and amount of the cosmetic and the physical characteristics of the skin before and after applying the cosmetic, and select the makeup method to be applied to the skin. for that reason,
2. Description of the Related Art Conventionally, various methods have been used to analyze and evaluate the unevenness of the skin surface such as wrinkles and pores, or the condition inside the skin such as spots and freckles.

As a method in this case, there is also a method of simply enlarging and photographing the skin and analyzing the surface condition of the skin based on the image. In this method, the unevenness of the skin surface such as small wrinkles and pores and spots and freckles are used. It is not possible to separately analyze and evaluate the state inside the skin such as. Therefore, as a method for separately analyzing and evaluating the skin surface state such as wrinkles and pores and the skin internal state such as spots and freckles, a method utilizing polarized light has been proposed (Japanese Patent Laid-Open No. 2-206426, etc.). .

That is, as shown in FIG. 7, light Li having a specific plane of polarization is projected onto the skin S through the first polarization filter 1a, and the reflected light is received through the second polarization filter 1b, so that the skin Forming an image of. In such an observation system, a part of the projected light Li is reflected by the surface and becomes surface-reflected light Ls. This surface-reflected light Ls has information on the surface roughness of the skin and maintains the same polarization plane as the projected light Li.
On the other hand, in addition to the projected light Li, the epidermis S ₁ of the skin repeats scattering and absorption, and is emitted from the skin surface again and internally reflected light Ld.
Becomes Therefore, the internal reflected light Ld has internal information such as spots and freckles on the epidermis S ₁ . Further, the internally reflected light Ld has lost the polarization property. Therefore,
When the polarization direction of the second polarization filter 1b is made different from that of the first polarization filter 1a during observation, the surface reflected light Ls is cut and an image is formed based on the internal reflected light Ld. Therefore, the second polarization filter 1b
Compared with the case where the polarization direction of (1) is set to be the same as that of the first polarization filter 1a, it becomes possible to clearly obtain a state such as a stain or freckle.

[0005]

However, even if the surface reflected light and the internal reflected light are separately observed using polarized light, the conventional method quantitatively evaluates the covering power such as foundation. It is not possible. Also, it is not possible to evaluate the transparency and dullness of bare skin. Therefore, it has been difficult to select the most suitable cosmetic for the skin.

The present invention is intended to solve the problems of the prior art as described above, and objectively evaluates the light transmittance of various coatings such as foundations and other cosmetic coatings or the epidermis of the skin itself. The purpose is to be able to.

[0007]

The inventors of the present invention evaluated the covering power, transparency, dullness, etc. of a film by calculating the power spectral density of the internal reflected light based on the internal reflected light from the film, and By finding the parameter T relating to the light transmittance of the coating or the parameter σ relating to the light diffusivity on the basis of the spectral density, it was found that it can be performed objectively, and has completed the first present invention. In addition, this method evaluates the light transmittance of the film changed by the surface treatment when the film is subjected to some surface treatment such as when applying a cosmetic such as a moisturizer or a drug to the skin. And found that it is also effective when
The present invention has been completed.

That is, the first aspect of the present invention is to project light from a light source through a first polarizing filter to each of an object having a film on its surface and an object having no film on its surface. , The reflected light is received through a second polarizing filter having a polarization direction different from that of the first polarizing filter, the power spectral density of the received light is obtained, and a parameter relating to the light transmittance of the film based on both power spectral densities. Alternatively, there is provided a method for evaluating light transmittance of a film, which comprises evaluating a light transmittance of the film by obtaining a parameter relating to the light diffusivity of the film.

As a second invention, the present invention provides a first light source for a surface of a subject having a coating on the surface of the subject and a surface of the subject before and after the surface treatment. Light is transmitted through the polarizing filter of No. 1, the reflected light is received through the second polarizing filter having a polarization direction different from that of the first polarizing filter, the power spectral density of the received light is obtained, and based on both power spectral densities Provided is a method for evaluating light transmittance of a film, which comprises evaluating a light transmittance of the film or a parameter concerning light diffusivity of the film to evaluate the light transmittance of the film changed by the surface treatment.

Further, the present invention is a device useful for carrying out the above-mentioned first or second method of the present invention, which comprises a light source and a first polarizing filter, and polarizes a subject having a film on its surface. , A second polarizing filter having a polarization direction different from that of the first polarizing filter, a light receiving means for receiving reflected light from the subject through the second polarizing filter, and a power of light received by the light receiving means. A calculation device for obtaining and storing the spectral density, calculating a parameter relating to the light transmittance of the coating or a parameter relating to the light diffusivity of the coating based on the power spectral density based on a plurality of measurement data, and a display means for displaying the calculation result. Provided is an apparatus for evaluating light transmittance of a coating having the above.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

FIG. 1 is a system configuration diagram of an apparatus according to an embodiment of the present invention. The apparatus shown in FIG. 1 includes a light source 2, a first polarization filter 1a provided in front of the light source 2, and a second polarization filter 1 having a polarization direction different from that of the first polarization filter 1a.
b, the reflected light from the object A to be detected by the second polarization filter 1b
The light receiving means 3 that receives light through the light receiving means 3 and the power spectral density of the light received by the light receiving means 3 are obtained and stored, and the parameter relating to the light transmittance of the film or the light diffusivity of the film is calculated based on the power spectral density based on a plurality of measurement data It comprises an arithmetic unit (not shown) for calculating parameters relating to the above, and display means (not shown) for displaying the arithmetic result.

Here, the light source 2 preferably emits white light, and, for example, a metal halide lamp, a fluorescent lamp, an incandescent lamp or the like can be provided.

The first polarizing filter 1a and the second polarizing filter 1b have different polarization directions. In particular, it is preferable to make the polarization directions of the first polarization filter 1a and the second polarization filter 1b orthogonal to each other in order to cut off the surface reflected light from the subject A and receive only the internal reflected light. .

As the light receiving means 3, an image pickup device such as a high-definition camera can be used. Further, as the light receiving means 3, it is preferable to output lightness information of the received light or information corresponding thereto (for example, G image of RGB image) to the arithmetic device in the subsequent stage. In other words, the covering power of cosmetics such as foundation is the ability to make color unevenness such as spots and freckles on bare skin difficult to see. Is known to be in close contact with. Therefore, the light receiving means does not output the chromaticity information of the received light to the arithmetic device in the subsequent stage, but outputs the lightness information, and causes the arithmetic device to calculate the power spectrum for the lightness information.
It becomes possible to easily carry out the evaluation of the light transmittance of the coating in practical use without complicating the device structure.

When the optical transparency of the coating is evaluated by using such an apparatus according to the method of the first aspect of the present invention, first, the object A having the coating on its surface is projected, and the reflected light is reflected. To the light receiving means 3 through the second polarizing filter 1b.
The light is received by and the power spectral density is calculated by the arithmetic unit. Preferably, as described above, the power spectral density of the lightness information of the light received by the arithmetic device or information corresponding thereto is calculated. Similarly, the power spectrum density of the reflected light of the subject A having no film is also calculated. Then, the parameter T relating to the light transmittance of the coating or the parameter σ relating to the light diffusivity of the coating is obtained based on the power spectral densities of both.

Here, the meaning of the parameter T relating to the light transmittance and the parameter σ relating to the light diffusivity of the coating, and the principle of the evaluation method of the present invention using these parameters will be described. This evaluation method was created by the present inventor on the assumption of the following model.

As shown in FIG. 2, let us consider a case in which the light Li is projected onto the subject A having the coating B and the internally reflected light Ld is received. Here, it is assumed that the coating B on the surface of the subject A has a light transmittance T, and the coating B has a blur function g (σ) according to a Gaussian distribution in terms of light diffusivity. Then, the image f ₁ (x, formed by the internal reflection light Ld
y) and the image f ₀ (x, y) formed by projecting the light Li on the subject A and receiving the reflected light in the same manner when the film B is not present are expressed by the following equation (2). Suppose you have a relationship.
In the formula (2), the light transmittance T is squared with respect to the image f ₁ (x, y) because the incident light Li is received as the internal reflected light Ld. This is because it is considered that the coating B passes twice.

(Equation 5)

The Fourier transform of this image f ₁ (x, y) is F
_{When 1} (u, v) and its power are Φ, these are expressed by the following equations (3) and (4).

(Equation 6)

(Equation 7)

Here, the power spectral density F is obtained by integrating the power Φ in the two-dimensional spatial frequency plane with respect to the ring-shaped region at a distance r _{j to} r _j + Δr from the origin.
_{When 1} (r _j ) is obtained, the following equation (5a) is obtained. Where:
j is the number of the ring area.

(Equation 8)

(Equation 9)

(Equation 10)

Similarly, the power spectral density F ₀ (r _j ) of the image f ₀ (x, y) formed when the film B is not present can be obtained.

Therefore, the power spectral density F ₁ (r _j ) of the image f ₁ (x, y) formed when the film B is present.
And the power spectral density F ₀ (r _j ) of the image f ₀ (x, y) formed when the film B is not present have the relationship of the following expression (1a).

[Equation 11]

Therefore, as shown in FIG. 3, when log (F ₁ (r _j ) / F ₀ (r)) is plotted against r ² , a linear relationship is obtained, and the intercept on the vertical axis is log T ² . Become. Thereby, the light transmittance T of the film B is obtained. In the present invention, the light transmittance T thus obtained is used as one of the parameters of the light transmittance of the film (that is, the parameter relating to the light transmittance of the film). Also, the slope of the straight line in FIG.
From (σ ^2/2) and made it, can be determined this by sigma. In the present invention, σ thus obtained is also used as one of the parameters of light transmittance (that is, the parameter relating to the light diffusivity of the film).

Here, the evaluation results regarding the light transmittance of the film obtained by the conventional sensory evaluation method and the correlation with these parameters are such that the evaluation items regarding the light transmittance are the covering power, transparency and dullness. Etc. It depends on which one of them is. The parameter T relating to the light transmittance and the parameter σ relating to the light diffusivity depending on the evaluation item.
Both may be used for evaluation, or either one may be used for evaluation.

As described above, in the process of obtaining the parameter T relating to the light transmittance or the parameter σ relating to the light diffusivity, due to the noise of the light receiving means 3 or the noise in the calculation processing at the time of the Fourier transform, the straight line of FIG. Sometimes does not show a negative slope, but for such noise, the taper is used prior to the Fourier transform.
Window function processing such as windows and Hanning windows can be performed.

The reason why the straight line in FIG. 3 does not show a negative slope is that the model of the formula (1a) is based on the assumption that the subject and the coating film are isotropic. It can be mentioned that the color unevenness such as skin stains and freckles is not necessarily circular and isotropic. In that case, considering the directionality of the received light, the above equation (1
Equation (1b) described below is used instead of a).

That is, the power Φ in the two-dimensional spatial frequency plane is the distance r _{j to} r _j + Δr from the origin, and the angles θ _{i to} θ.
_When the power spectral density P (r _j , θ _i ) is obtained by integrating in the region of _i + Δθ, the following equation (5b) is obtained.
become that way. Here, j and i are the numbers of the divided areas in the radial direction and the angular direction.

(Equation 12)

Therefore, when the power spectral density with the coating B is P ₁ (r _j , θ _i ) and the power spectral density without the coating B is P ₀ (r _j , θ _i ), they are both It has the relationship of the following expression (1b).

(Equation 13) (In the formula, log represents a natural logarithm, P ₁ (r _j , θ _i ): power spectrum density of an object having a film on the surface P ₀ (r _j , θ _i ): no film on the surface Power spectral density of sample T: parameter relating to light transmittance of coating σ: parameter relating to light diffusivity of coating)

Therefore, for r _j ²

[Equation 14] Plotting gives a linear relationship with a slope of − (σ ² /
2) and the intercept becomes logT ² . Accordingly, even when the subject A or the coating B is not isotropic, the parameter σ related to the diffusivity of the coating B and the parameter T related to the light transmittance can be obtained.

Although the principle of the first aspect of the present invention has been described above, the principle of the second aspect of the present invention can be considered in the same manner as the first aspect of the present invention. That is, in the second aspect of the present invention, the power spectral densities are obtained both before and after the surface treatment. Here, the power spectral density before the surface treatment is
It may be considered that the power spectrum density in the case where the film of the first present invention is absent corresponds to the power spectrum density after the surface treatment and the power spectrum density in the case where the film of the first present invention is present. it can.

Further, in the method of the first aspect of the present invention, it is necessary to perform the measurement operation both when the coating film for evaluating the light transmittance is present on the surface of the subject and when it is not. It is premised that the coating of (2) can be removed from the body of the subject, but the method of the second aspect of the present invention does not have such a limitation. The present invention can be applied to any coating, whether it is removable from the body of the subject or integrated with the body of the subject. Therefore, for example, the present invention can be applied to the case of evaluating the change occurring in the stratum corneum or epidermis when the stratum corneum of the skin surface layer or epidermis is treated with a cosmetic such as a moisturizer or a drug.

As described above, in the present invention, the parameter relating to the light transmittance of the coating or the parameter relating to the light diffusivity of the coating is obtained based on the power spectral density of the internal reflection light from the coating. These parameters are physical properties of the film, and their values have a high correlation with the conventional subjective evaluation of the light transmittance such as the covering power and transparency of the film. Therefore, instead of the conventional subjective evaluation, it becomes possible to objectively evaluate the light transmittance of the film by the parameters of the present invention.

When the surface of the film is subjected to some surface treatment such as when a cosmetic such as a moisturizer or a drug is applied to the skin, the film is removed from the film both before and after the surface treatment. By obtaining the power spectrum density of the internally reflected light of and obtaining these parameters, it becomes possible to evaluate the light transmittance of the film changed by the surface treatment. Further, this also makes it possible to evaluate the effectiveness of the surface treatment applied to the film.

[0034]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below based on embodiments.

Example 1 In the apparatus configuration shown in FIG. 1, as the light source 2, two metal halide lamps (SMT-1200, manufactured by RDS) arranged with a center interval of 1000 mm were used. These were installed at a distance of 1600 mm from the subject A. The first polarizing filter 1a is POLARO.
HN32 (50 cm × 120 cm) manufactured by ID Co. was used. An electronic camera (XC-009, manufactured by Sony Corporation) was provided as the light receiving means 3. In addition, on the front surface of this electronic camera, as the second polarizing filter 1b, a polarizing filter (5 cm × 5c) similar to the first polarizing filter 1a is used.
m) was arranged so that the polarization direction thereof was orthogonal to the polarization direction of the first polarizing filter 1a. The computing device connected to the electronic camera is Q6 manufactured by Macintosh.
50 is provided.

As the test object A, three types of gray filters A, B, and C having different transmittances on a substrate (A-19 manufactured by IC Color Co., Ltd., IC Color Overlay) are used.
4, A-195, A-196) were respectively prepared. Then, polarized light was projected onto each subject by the above device, and the reflected light was received by an electronic camera to obtain the power spectrum density. in this case,
The light projection angle to the subject is about 15 °, and the light receiving angle is about 0 °.
And The power spectral density was similarly obtained when the gray filters A, B, and C were not placed on the substrate.

However, in calculating these power spectral densities, the power spectral density P ₁ when the gray filter is mounted and the power when the gray filter is not mounted are taken into consideration in consideration of the isotropic property of the object and the gray filter. As a ratio with the spectral density P ₀ , the ratio of the two is integrated over all angles of the space as in the above equation (1b), R (r
_j ) asked.

(Equation 15)

Further, assuming that the noise of the camera system is additive noise, the power spectral densities actually measured when the gray filter is mounted and when it is not mounted are represented by the following equations.

When a gray filter is mounted:

(Equation 16)

When no gray filter is mounted:

[Equation 17]

In these equations, N (θ, r) is the power spectrum of the camera system noise. Further, the power spectrum N (r _j , θ _i ) of noise of this camera system is
It was determined by actually measuring a uniform gray color chart.

Thus, the power spectral density P ₁ (r _j )
And P ₀ (r _j ) are modified, the above equation (1b) becomes the following equation (1c).

(Equation 18)

Therefore, in order to check that this equation (1) holds, r _j ² and

[Equation 19] And are plotted. The result is shown in FIG.

Further, based on the power spectral densities of the gray filters A, B and C with and without the gray filters A and B, the parameter T relating to the light transmittance of each of the gray filters A, B and C is set. I asked. Table 1 shows the results.
Shown in

[0045]

[Table 1]

Furthermore, of the projected light, a loss due to surface reflection at each of the gray filters A, B, and C is conceivable. Therefore, the loss ratio S is obtained by a haze meter, the parameter T is corrected, and after the correction, Parameter (T / S) ²
I got These results are also shown in Table 1.

On the other hand, the transmittance of each gray filter was measured with a haze meter, and the result was plotted against the parameters T ² and (T / S) ² relating to the light transmittance obtained as described above. The result is shown in FIG.

From FIG. 5, the parameters T ² and (T / S) ² relating to the light transmittance obtained as described above have a high correlation with the actually measured transmittance by the haze meter, and particularly the parameter (T / S). ^It can be seen that ² agrees with the measured transmittance by the haze meter. Therefore, it is understood that the transmittance of the coating can be evaluated more favorably by the parameter relating to the light transmittance obtained by this method.

Example 2 Using the same apparatus as in Example 1, a fixed amount (0.4 mg / cm ² ) of various commercially available foundations (a to i) was applied to the face.
In the case where a foundation coating film was formed by applying, the parameter T relating to the light transmittance of the foundation coating film was obtained.

On the other hand, the covering power of each foundation coating film was evaluated on a scale of 5 from 1 to 5 according to the following criteria by a subjective evaluation by a total of 5 women, 2 women and 3 men, and the average value was obtained. . The evaluation criteria in this case are as follows.

[Subjective Evaluation Criteria] 1: Low Covering Power 2: Slightly Low Covering Power 3: Moderate Covering Power 4: Moderately High Covering Power 5: High Covering Power

Then, the parameter T ² obtained by the method of the present invention and the covering power by subjective evaluation were plotted.
The result is shown in FIG. It can be seen from FIG. 6 that there is a high correlation (correlation coefficient R = 0.92) between the parameter T obtained by the method of the present invention and the covering power by subjective evaluation.

[0053]

EFFECTS OF THE INVENTION According to the present invention, it is possible to objectively evaluate the light transmittance of a cosmetic coating such as foundation or various coatings such as epidermis of the skin itself.

[Brief description of the drawings]

FIG. 1 is a system configuration diagram of an apparatus according to an embodiment.

FIG. 2 is an explanatory diagram of the principle of the present invention.

FIG. 3 is a relationship diagram between power spectral density and r.

FIG. 4 is a relationship diagram between power spectral density and r in the example.

FIG. 5 is a relationship diagram between parameters relating to light transmittance and measured transmittance.

FIG. 6 is a relationship diagram between parameters relating to light transmittance and subjective evaluation of covering power.

FIG. 7 is an explanatory diagram of surface reflection and internal reflection when polarized light is projected on the skin.

[Explanation of symbols]

 A subject B coating 1a first polarizing filter 1b second polarizing filter 2 light source 3 light receiving means

Claims (15)

[Claims] 1. A light source is projected from a light source through a first polarizing filter to each of an object having a film on its surface and an object having no film on its surface, and the reflected light is Light is received through a second polarization filter having a polarization direction different from that of the polarization filter, and the power spectral density of the received light is obtained. A method for evaluating the light transmittance of a film, which comprises evaluating the light transmittance of the film by obtaining it. 2. As the power spectral density, a distance r _{j to} r _j + Δr from an origin in a two-dimensional spatial frequency plane.
Power spectral density F for the ring region of
(r _j ) is calculated and the following equation (1a) is obtained. (In the formula, log represents a natural logarithm, F ₁ (r _j ): power spectrum density of an object having a film on the surface F ₀ (r _j ): power spectrum of an object having no film on the surface The density T is a parameter relating to the light transmittance of the coating, σ is a parameter relating to the light diffusivity of the coating, and the parameter T relating to the light transmittance or the parameter σ relating to the light diffusivity of the coating is obtained.
A method for evaluating light transmittance of a film as described. 3. As a power spectral density, a distance r _{j to} r _j + Δ from an origin in a two-dimensional spatial frequency plane.
r, angle θ _i ~θ _i + Δθ power spectral density P (r _j, θ _i) for the region of the seek, following formula (1b) [Equation 2] (In the formula, log represents a natural logarithm, P ₁ (r _j , θ _i ): power spectrum density of an object having a film on the surface P ₀ (r _j , θ _i ): no film on the surface The power spectral density of the object T: a parameter relating to the light transmittance of the coating σ: a parameter relating to the light diffusivity of the coating) is used to obtain the parameter T relating to the light transmittance or the parameter σ relating to the light diffusivity of the coating. 1
A method for evaluating light transmittance of a film as described. 4. The method for evaluating light transmittance of a coating film according to claim 1, wherein the power spectral density is obtained for lightness information of received light. 5. A white light source is used as the light source.
4. The method for evaluating light transmittance of a film according to any one of 3 to 3. 6. The light transmittance evaluation method according to claim 1, wherein the film is a cosmetic coating film on the skin. 7. A light source projects light onto a surface of a subject having a film on its surface before and after the surface treatment of the subject through a first polarizing filter. The reflected light is received through a second polarizing filter having a polarization direction different from that of the first polarizing filter, the power spectral density of the received light is obtained, and the parameter relating to the light transmittance of the coating or the coating based on both power spectral densities. A method for evaluating the light transmittance of a film, characterized in that the light transmittance of the film changed by the surface treatment is evaluated by determining a parameter relating to the light diffusivity of the film. 8. As a power spectral density, a distance r _{j to} r _j + Δr from an origin in a two-dimensional spatial frequency plane.
Power spectral density F for the ring region of
(r _j ) is calculated and the following equation (1a) is obtained. (In the formula, log represents a natural logarithm, F ₁ (r _j ): power spectral density of the subject after the surface treatment F ₀ (r _j ): power of the subject before the surface treatment The spectral density T is a parameter relating to the light transmittance of the coating, σ is a parameter relating to the light diffusivity of the coating, and the parameter T relating to the light transmittance or the parameter σ relating to the light diffusivity of the coating is obtained.
A method for evaluating light transmittance of a film as described. 9. As the power spectral density, a distance r _{j to} r _j + Δ from an origin in a two-dimensional spatial frequency plane.
r, angle θ _i ~θ _i + Δθ power spectral density P (r _j, θ _i) for the region of the seek, following formula (1b) [Expression 4] (In the formula, log represents a natural logarithm, P ₁ (r _j , θ _i ): power spectral density of the subject after the surface treatment P ₀ (r _j , θ _i ): before the surface treatment Of the power spectral density T for the subject of: T: parameter relating to light transmittance of coating, σ: parameter relating to light diffusivity of coating, and obtaining parameter T relating to light transmittance or parameter σ relating to light diffusivity of coating. Item 7
A method for evaluating light transmittance of a film as described. 10. The method for evaluating the light transmittance of a coating film according to claim 7, wherein the power spectral density is obtained for lightness information of received light. 11. The method for evaluating the light transmittance of a film according to claim 7, wherein a white light source is used as the light source. 12. The method for evaluating the light transmittance of a film according to claim 7, wherein the film is the stratum corneum of the skin or the epidermis. 13. A light projecting means, comprising a light source and a first polarizing filter, for projecting polarized light to a subject having a film on its surface, a second polarizing filter having a polarization direction different from that of the first polarizing filter, and the subject. The light receiving means for receiving the reflected light from the second polarization filter through the second polarizing filter, the power spectral density of the light received by the light receiving means is obtained and stored, and the light transmittance of the film is calculated based on the power spectral density based on a plurality of measurement data. A light transmittance evaluation device for a film, comprising: a calculation device for calculating a parameter or a parameter relating to the light diffusion property of the film; and a display means for displaying the calculation result. 14. The film light transmittance evaluation device according to claim 13, wherein the light receiving means outputs the brightness information of the received light to the arithmetic device. 15. The film light transmittance evaluation device according to claim 13, wherein the light receiving means is a high-definition camera.