Skin surface shape evaluation method, skin surface shape evaluation system, skin surface shape evaluation program, and skin surface shape evaluation device

Abstract

To provide an evaluation method that makes it easy to imagine the shape of the skin surface.SOLUTION: A method according to an embodiment of the present invention includes: acquiring measurement data indicating a measurement result of a shape of a surface of skin of a subject; generating a plurality of pieces of extraction data constituted by frequency components belonging to a plurality of frequency segments among frequency components constituting the measurement data; deriving a value of an index related to the shape of the surface of the skin for each piece of the extraction data; and evaluating the shape of the surface of the skin on the basis of the derived value of the index for each piece of the extraction data.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a method for evaluating the shape of the skin surface, a system for evaluating the shape of the skin surface, a program for evaluating the shape of the skin surface, and an apparatus for evaluating the shape of the skin surface.

Background Art

[0002] Conventionally, the shape of the skin surface has often been used as a material for judging whether the skin is in a healthy state. Furthermore, the shape of the skin surface is related to the texture of the skin that can be actually perceived by humans, such as the gloss, luster, and smoothness of the skin from the quality of the luster. Therefore, it is important to evaluate the shape of the skin surface.

[0003] For a long time, the shape of the skin surface in the range of several millimeters that is difficult to see with the naked eye has been evaluated by sensory evaluation based on visual perception using a microscope. In recent years, it has been known to evaluate the shape of the skin surface using data obtained by transferring an image or the shape of the skin surface to a silicone gel.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, with the conventional methods, even when looking at the result of evaluating the shape of the skin surface, it was difficult to form a specific image of the shape of the skin surface.

[0006] Therefore, an object of the present invention is to provide an evaluation method in which an image of the shape of the skin surface can be easily formed.

Means for Solving the Problems

[0007] The method according to an embodiment of the present invention acquires measurement data indicating the measurement result of the shape of the surface of the skin of a subject, generates a plurality of extraction data composed of frequency components belonging to each of a plurality of frequency ranges among the frequency components constituting the measurement data, derives a value of an index related to the shape of the surface of the skin for each of the extraction data, and evaluates the shape of the surface of the skin based on the value of the index for each of the derived extraction data.

Advantages of the Invention

[0008] According to the present invention, it is possible to provide an evaluation method in which an image of the shape of the surface of the skin is likely to come to mind.

Brief Description of the Drawings

[0009] [Figure 1] It is a diagram for explaining an overview of skin surface shape evaluation according to an embodiment of the present invention. [Figure 2] It is a configuration diagram of a skin surface shape evaluation system according to an embodiment of the present invention. [Figure 3] It is a functional block diagram of a skin surface shape evaluation system according to an embodiment of the present invention. [Figure 4] It is a flowchart of skin surface shape evaluation according to an embodiment of the present invention. [Figure 5] It is a diagram for explaining the relationship between a cut-off value, the shape of the surface of the skin, and a gloss index value according to an embodiment of the present invention. [Figure 6] It is a diagram for explaining the relationship between the cut-off value for each age group, the shape of the surface of the skin, according to an embodiment of the present invention. [Figure 7] It is a diagram for explaining the relationship between the cut-off value for each age group and the gloss index value according to an embodiment of the present invention. [Figure 8] It is a diagram for explaining principal component analysis according to an embodiment of the present invention. [Figure 9] It is an example of a screen showing an evaluation result of the shape of the surface of the skin according to an embodiment of the present invention. [Figure 10] It is a diagram for explaining the improvement of the gloss index value according to an embodiment of the present invention. [Figure 11] FIG. 10 is a diagram for explaining an improvement in a gloss index value according to an embodiment of the present invention. [Figure 12] FIG. 2 is a block diagram showing an example of the hardware configuration of a skin surface shape evaluation device and a user terminal according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0011] <Summary> FIG. 1 is a diagram illustrating an overview of skin surface shape evaluation according to one embodiment of the present invention. In one embodiment of the present invention, first, the three-dimensional shape of the surface of a skin replica (e.g., [Skin replica] in FIG. 1) is measured. Note that the three-dimensional shape of the surface of actual skin may also be measured. Next, a waveform representing the shape of the skin surface (specifically, a waveform representing the shape of the skin surface when viewed from the side (i.e., cross section); for example, [Waveform representing skin surface shape] in FIG. 1) is formed. Next, a waveform is formed in which wavelengths smaller than each of a plurality of thresholds (i.e., small irregularities) are removed from the waveform representing the skin surface shape (e.g., [Waveform after small irregularities are removed] in FIG. 1). Note that a waveform in which wavelengths larger than each of a plurality of thresholds (i.e., large irregularities) are removed from the waveform representing the skin surface shape may also be formed.

[0012] As shown in the [waveform indicating the shape of the skin surface] of FIG. 1, various irregularities such as small irregularities and large irregularities are mixed on the skin surface. The light irradiated on the skin is reflected in various directions according to the irregularities. On a surface with many irregularities, it is evenly reflected in all directions, and almost no gloss is felt. On a surface with few irregularities and smooth, it emits strong gloss. That is, it can be said that the gloss state of the skin is one of the indicators showing the shape of the skin surface. Furthermore, although the irregularities of the skin have a very complex waveform, considering it as a superposition of waveforms of a plurality of different frequencies (wavelengths may be used instead of frequencies), for the waveform from which components in a predetermined frequency (wavelengths may be used instead of frequencies as described above) range are removed, by examining the index value, it becomes possible to more easily understand the characteristics of the shape of the skin surface. The components corresponding to each of the plurality of waveforms constituting the waveform indicating the shape of the skin surface may be referred to as waveform components, frequency components, or wavelength components.

[0013] In one embodiment of the present invention, based on the surface reflection in each waveform (that is, each irregularity) from which wavelengths smaller than each threshold value of a plurality of threshold values are removed, the state of the gloss of the skin caused by small irregularities (texture) of the skin and the state of the gloss of the skin caused by large irregularities (overall smoothness (pores and fine wrinkles)) of the skin can be evaluated. In the present specification, removing a wavelength from a waveform includes not only a mode of removing a component having a specific wavelength from a signal or data indicating the waveform, but also a mode of attenuating the amplitude of a component having a specific wavelength included in the signal or data indicating the waveform. Thereby, a component having a specific frequency can be extracted from the signal or data indicating the waveform.

[0014] In one embodiment of the present invention, the evaluation result of the shape of the skin surface can be used for a beauty staff or the like to select cosmetics, beauty-related services, etc. to recommend to customers, or for researching or developing cosmetics, beauty-related services, etc.

[0015] <Overall configuration> FIG. 2 is a configuration diagram of a skin surface shape evaluation system 1 according to an embodiment of the present invention. The skin surface shape evaluation system 1 according to an embodiment of the present invention includes a skin surface shape evaluation device 10 and a user terminal 20. The skin surface shape evaluation device 10 and the user terminal 20 can transmit and receive data via an arbitrary network. Each will be described below.

[0016] The skin surface shape evaluation device 10 is a computer (for example, a server) for evaluating the shape of the surface of the skin of a subject 30 (for example, a customer of a store selling cosmetics). Note that the skin may be the skin of any part of a human, such as the skin of the face, neck, hands, or feet.

[0017] The user terminal 20 is a computer (for example, a personal computer, tablet, smartphone, etc.) operated by the subject 30 or a beauty staff member. For example, the user terminal 20 transmits the result of measuring the shape of the surface of the skin of the subject 30 to the skin surface shape evaluation device 10, and receives and displays the result of evaluating the shape of the surface of the skin from the skin surface shape evaluation device 10.

[0018] In FIG. 2, the skin surface shape evaluation device 10 and the user terminal 20 are described as separate computers, but they may be implemented on one computer (the skin surface shape evaluation device 10 may include at least part of the functions of the user terminal 20, and the user terminal 20 may include at least part of the functions of the skin surface shape evaluation device).

[0019] <Functional Configuration> FIG. 3 is a functional block diagram of a skin surface shape evaluation system 1 according to an embodiment of the present invention.

[0020] <<Skin Surface Shape Evaluation Device>> The skin surface shape evaluation device 10 can include a skin surface shape acquisition unit 101, a frequency component extraction unit 102, an index value derivation unit 103, an evaluation unit 104, and a screen generation unit 105. The skin surface shape evaluation device 10 functions as the skin surface shape acquisition unit 101, the frequency component extraction unit 102, the index value derivation unit 103, the evaluation unit 104, and the screen generation unit 105 by executing a program.

[0021] The skin surface shape acquisition unit 101 acquires measurement data indicating the measurement result of the shape of the surface of the skin of the subject 30. The skin surface shape acquisition unit 101 may acquire the above measurement data by acquiring a signal indicating the above measurement result. The above measurement result may be a measurement result of the three-dimensional shape of the surface of the skin. For example, the skin surface shape acquisition unit 101 acquires measurement data indicating the measurement result of the shape of the surface of the skin of the subject 30 from the user terminal 20. Note that the shape of the surface of the skin may be measured directly (the actual skin is measured) or indirectly (a replica of the skin is measured).

[0022] The frequency component extraction unit 102 generates a plurality of extraction data composed of frequency components belonging to each of a plurality of divisions related to frequency (sometimes referred to as frequency divisions) among the frequency components constituting the measurement data acquired by the skin surface shape acquisition unit 101. In one embodiment, the frequency component extraction unit 102 generates a plurality of extraction data composed of frequency components belonging to each of all preset frequency divisions among the frequency components constituting the above measurement data. In another embodiment, the frequency component extraction unit 102 generates a plurality of extraction data composed of frequency components belonging to a part of the preset frequency divisions among the frequency components constituting the above measurement data. Note that only the upper limit of the frequency division may be specified, only the lower limit may be specified, or both the upper limit and the lower limit may be specified.

[0023] For example, the frequency component extraction unit 102 can extract, for each of a plurality of frequency thresholds, frequency components having frequencies smaller than each threshold from the frequency components constituting the measurement data acquired by the skin surface topography acquisition unit 101. For each of a plurality of wavelength thresholds, the frequency component extraction unit 102 removes wavelength components having wavelengths smaller than each threshold or attenuates the amplitude of wavelength components having wavelengths smaller than each threshold from the wavelength components constituting the measurement data acquired by the skin surface topography acquisition unit 101. In this way, frequency components having the above-mentioned specific frequencies are extracted.

[0024] The frequency component extraction unit 102 can output information indicating a waveform obtained by removing frequency components having frequencies greater than a specific frequency threshold (sometimes referred to as a cutoff value) (i.e., frequency components having wavelengths smaller than the wavelength corresponding to the cutoff value) from the frequency components constituting the measurement data acquired by the skin surface shape acquisition unit 101 (i.e., frequency components constituting a waveform indicating the shape of the skin surface) using, for example, a low-pass filter. This allows information indicating a waveform formed by components having frequencies smaller than the cutoff value (sometimes referred to as a cutoff frequency) for the frequency to be obtained. Similarly, information indicating a waveform formed by components having wavelengths larger than the wavelength corresponding to the cutoff frequency (sometimes referred to as a cutoff wavelength) can be obtained. (i) Information indicating a waveform formed by components having frequencies smaller than the cutoff frequency and (ii) Information indicating a waveform formed by components having wavelengths larger than the cutoff wavelength may be examples of information indicating a waveform obtained by removing frequency components having wavelengths smaller than the threshold from the frequency components constituting a waveform indicating the shape of the skin surface.

[0025] The frequency component extraction unit 102 may output information indicating a waveform in which components having frequencies higher than the cut-off frequency are removed for each of the cut-off frequencies using a plurality of cut-off frequencies. The frequency component extraction unit 102 may output information indicating a waveform in which components having wavelengths smaller than the cut-off wavelength are removed for each of the cut-off wavelengths using a plurality of cut-off wavelengths.

[0026] For example, the frequency component extraction unit 102 outputs information indicating a waveform in which components having wavelengths smaller than the cut-off wavelength are removed for each of the cut-off wavelengths while varying the magnitude of the cut-off wavelength variously between 5 μm and 4000 μm. The above-described variation range of the cut-off wavelength may be 10 μm or more and 1500 μm or less, may be 20 μm or more and 1200 μm or less, or may be 30 μm or more and 1050 μm or less.

[0027] As described above, the cut-off value may be represented by frequency or may be represented by wavelength. The cut-off value regarding frequency may be referred to as the cut-off frequency in some cases. The cut-off value regarding wavelength may be referred to as the cut-off wavelength in some cases. Further, removing components having frequencies higher than or wavelengths smaller than the threshold value (cut-off value) includes at least one of removing components having frequencies higher than or wavelengths smaller than the threshold value (cut-off value) and attenuating the amplitude of the components.

[0028] Note that arbitrary information processing may be performed before extracting the frequency components belonging to each frequency section. For example, processing using a high-pass filter may be performed, or processing for correcting the inclination of the waveform by planar processing or the like may be performed.

[0029] The index value derivation unit 103 derives the value of an index regarding the shape of the surface of the skin for each of the extraction data generated by the frequency component extraction unit 102.

[0030] For example, an index relating to the shape of the skin surface is the degree of surface reflectance of the skin surface. The more minute irregularities there are on the surface of an object, the more light is scattered on the surface of the object, and the lower the degree of surface reflectance. On the other hand, the smoother the surface of the object, the less light is scattered on the surface of the object, and the higher the degree of surface reflectance.

[0031] Surface reflection from the skin surface is an important factor in creating a beautiful skin luster. For example, the degree of surface reflection from the skin surface is expressed using surface reflectance (hereinafter also referred to as "gloss index value"; for example, the sum of reflectance from 0° to 70° on the incident surface).

[0032] For example, the index value derivation unit 103 derives the gloss index value using a known method such as the Monte Carlo method. The index value derivation unit 103 derives the gloss index value at each threshold (cutoff value) by repeating the process of deriving the gloss index value while sequentially changing the threshold (cutoff value). This allows information indicating the relationship between the cutoff value and the gloss index value to be obtained. By expressing the relationship between the cutoff value and the gloss index value on a two-dimensional plane, a cutoff value-gloss index value diagram can be obtained.

[0033] The evaluation unit 104 evaluates the shape of the skin surface based on the index value derived by the index value derivation unit 103 for each piece of extracted data.

[0034] [Evaluation of skin irregularity (PC2)] For example, the evaluation unit 104 can perform evaluation (e.g., quantify) using variables (e.g., the second principal component PC2 described in detail later) extracted by multivariate analysis (e.g., principal component analysis) of a threshold value (cutoff value) and an index value related to the shape of the skin surface (e.g., gloss index value). The multivariate analysis derives, for example, one or more basis vectors (which may also be referred to as eigenvectors, principal components, etc.) and weighting coefficients for each basis vector.

[0035] Specifically, the evaluation unit 104 extracts the first principal component PC1 and the second principal component PC2 by performing principal component analysis on the relationship between a plurality of cut-off values and the gloss index values corresponding to each cut-off value. The evaluation unit 104 represents the relationship between the cut-off value and the gloss index value obtained from the measurement result of the surface shape of the skin of the subject 30 in terms of PC1 and PC2, and can use the score of PC2 of the subject 30 (also referred to as factor score or principal component score) as the degree of skin unevenness (that is, the score of beautiful skin (beautiful texture)).

[0036] [Evaluation of Skin Texture] As described above, the waveform indicating the surface shape of the skin can be expressed as a superposition of a plurality of components having different wavelengths from each other (that is, waveform components, frequency components, or wavelength components). The evaluation unit 104 may evaluate the skin texture of the subject 30 based on the waveform component having a relatively short wavelength (which may be referred to as a short-wavelength component) when the waveform indicating the surface shape of the skin is represented as a superposition of a plurality of waveform components. The above short-wavelength component may be one or more waveform components having a wavelength equal to or less than the first threshold value or less than the first threshold value. The first threshold value is, for example, 500 μm or more and 600 μm or less.

[0037] For example, the evaluation unit 104 can evaluate the skin texture of the subject 30 based on one or more waveform components having a wavelength of 600 μm or less when the waveform indicating the surface shape of the skin is represented as a superposition of a plurality of waveform components. The above first threshold value may be 550 μm or 500 μm. The above short-wavelength component may be one or more waveform components having a wavelength equal to or less than the first threshold value or less than the first threshold value and having a wavelength equal to or more than the second threshold value or exceeding the second threshold value. The second threshold value is a value smaller than the first threshold value.

[0038] For example, the evaluation unit 104 can evaluate (e.g., quantify (e.g., use the gloss index value as a skin texture score)) the skin texture of the subject 30 based on the short wavelength portion of the cutoff value-gloss index value diagram (specifically, based on the gloss index value in the region of the cutoff wavelength-gloss index value diagram that is shorter wavelength than the extreme point (e.g., the minimum point) of the second principal component PC2).

[0039] [Evaluation of overall skin smoothness] The evaluation unit 104 may evaluate the overall smoothness of the subject's 30 skin based on waveform components with relatively long wavelengths (sometimes referred to as long-wavelength components) when a waveform indicating the shape of the skin surface is expressed as a superposition of multiple waveform components. As described above, the wavelengths of the multiple waveform components are different from each other. The long-wavelength components may be one or more waveform components having wavelengths greater than or equal to the first threshold. As described above, the first threshold is, for example, 500 μm or more and 600 μm or less.

[0040] For example, when a waveform indicating the shape of the skin surface is expressed as a superposition of multiple waveform components, the evaluation unit 104 can evaluate the overall smoothness of the subject's 30 skin based on one or more waveform components having a wavelength of 500 μm or more. The first threshold value may be 550 μm or 600 μm. The long wavelength component may be one or more waveform components having a wavelength greater than or equal to the first threshold value and a wavelength less than or equal to a third threshold value. The third threshold value is a value greater than the first threshold value.

[0041] For example, the evaluation unit 104 can evaluate (e.g., quantify (e.g., use the gloss index value as a score for the overall smoothness of the skin)) the overall smoothness of the subject 30's skin based on the long wavelength portion of the cutoff value-gloss index value diagram (specifically, based on the gloss index value in the region of the cutoff wavelength-gloss index value diagram that is longer wavelength than the extreme point (e.g., the minimum point) of the second principal component PC2).

[0042] The screen generation unit 105 generates a screen for presenting various types of information to the user. Examples of the above-mentioned user include the subject 30, researchers, beauty staff, etc. The screen generation unit 105 generates, for example, a screen for presenting the score of the second principal component (factor score, principal component score) described above to the user as the degree of skin unevenness. The screen generation unit 105 may generate a screen for presenting to users such as the subject 30 and beauty staff the results of evaluating the degree of skin unevenness, the texture of the skin, and the overall smoothness of the skin based on the shape of the skin surface. For example, the screen generation unit 105 causes the generated screen to be displayed on the user terminal 20.

[0043] <<User Terminal>> The user terminal 20 can include a skin surface shape acquisition unit 201, a skin surface shape transmission unit 202, an evaluation reception unit 203, and a display unit 204. The user terminal 20 functions as the skin surface shape acquisition unit 201, the skin surface shape transmission unit 202, the evaluation reception unit 203, and the display unit 204 by executing a program.

[0044] The skin surface shape acquisition unit 201 acquires measurement data indicating the measurement result of the shape of the surface of the skin of the subject 30.

[0045] The skin surface shape transmission unit 202 transmits the measurement data acquired by the skin surface shape acquisition unit 201 to the skin surface shape evaluation device 10.

[0046] The evaluation reception unit 203 receives from the skin surface shape evaluation device 10 the result of evaluating the shape of the surface of the skin of the subject 30.

[0047] The display unit 204 displays the result of evaluating the shape of the surface of the skin of the subject 30 (specifically, a screen for presenting to users such as the subject 30 and beauty staff the results of evaluating the degree of skin unevenness, the texture of the skin, and the overall smoothness of the skin based on the shape of the skin surface).

[0048] <Method> FIG. 4 is a flowchart of a skin surface shape evaluation process according to an embodiment of the present invention.

[0049] In step 1 (S1), the skin surface shape evaluation device 10 acquires measurement data indicating the measurement result of the shape of the surface of the skin of the subject 30 from the user terminal 20.

[0050] In step 2 (S2), the skin surface shape evaluation device 10 generates a plurality of extracted data composed of frequency components belonging to each of a plurality of frequency ranges among the frequency components constituting the measurement data acquired in S1.

[0051] In step 3 (S3), the skin surface shape evaluation device 10 derives the value of an index regarding the shape of the surface of the skin for each of the extracted data generated in S2.

[0052] In step 4 (S4), the skin surface shape evaluation device 10 evaluates the shape of the surface of the skin based on the value of the index for each of the extracted data derived in S3.

[0053] In step 5 (S5), the skin surface shape evaluation device 10 causes the user terminal 20 to display the result evaluated in S4 (specifically, a screen for presenting to the user such as the subject 30 or a beauty staff member the result of evaluating the degree of unevenness of the skin, the texture of the skin, and the overall smoothness of the skin based on the shape of the surface of the skin).

[0054] FIG. 5 is a diagram for explaining the relationship between the cut-off value, the shape of the skin surface, and the gloss index value according to an embodiment of the present invention. In the embodiment described in relation to FIG. 5, a cut-off wavelength is used as the cut-off value. Using FIG. 5, a graph which is an example of the above-described cut-off value - gloss index value diagram and computer graphics of a virtual skin surface corresponding to each case where the cut-off wavelengths are 32 μm, 192 μm, and 1024 μm are explained. In FIG. 5, the horizontal axis of the graph indicates the cut-off value, and the vertical axis of the graph indicates the gloss index value (which may be referred to as the gloss index value corresponding to the cut-off value) when frequency components having wavelengths smaller than each cut-off value are removed. Each of the three computer graphics shown in FIG. 5 is a computer graphic of the skin surface reproduced based on information indicating waveforms in which components having wavelengths smaller than each cut-off wavelength are removed, obtained when the cut-off wavelengths are 32 μm, 192 μm, and 1024 μm, respectively.

[0055] Cut-off wavelength: 32 μm is the original data. At a cut-off wavelength of 192 μm, the unevenness on the surface of the dermal papilla disappears and the texture is reflected. At a cut-off wavelength of 1024 μm, the texture also disappears and pores and fine wrinkles are reflected. Thus, by cutting off the unevenness, the shape of the skin surface can be characterized. When the cut-off wavelength is increased to smooth the surface, the gloss index value increases.

[0056] FIG. 6 is a diagram for explaining the relationship between the cut-off value of each age group and the shape of the skin surface according to an embodiment of the present invention. In the embodiment described in relation to FIG. 6, a cut-off wavelength is used as the cut-off value. In FIG. 6, an image showing the original shape of the skin of a person in their 20s and a person in their 40s, and computer graphics of the skin surface reproduced based on information indicating waveforms in which components having wavelengths smaller than each cut-off wavelength are removed in the case of a short cut-off wavelength and in the case of a long cut-off wavelength are shown.

[0057] As shown in the top row of Figure 6, for people in their twenties, a short cutoff wavelength results in many fine structures (texture) (i.e., a low gloss index value), while a long cutoff wavelength results in few large structures (pores and fine wrinkles) and a smoother appearance (i.e., a high gloss index value).

[0058] As shown in the bottom row of Figure 6, for people in their 40s, a short cutoff wavelength results in fewer fine structures (i.e., a high gloss index value), while a long cutoff wavelength results in more large structures (pores and fine wrinkles) and less smoothness (i.e., a low gloss index value).

[0059] FIG. 7 is a diagram illustrating the relationship between the cutoff value and gloss index value for each age group according to one embodiment of the present invention. In the embodiment described with reference to FIG. 7, a cutoff wavelength is used as the cutoff value. FIG. 7 illustrates a graph that is an example of a cutoff value-gloss index value diagram for A (in their 20s) and B (in their 40s). In FIG. 7, the horizontal axis of the graph indicates the cutoff wavelength, and the vertical axis of the graph indicates the gloss index value when frequency components having wavelengths shorter than each cutoff wavelength are removed. The images shown in FIG. 7 are images showing the skin of A (in their 20s) and B (in their 40s).

[0060] As shown in Figure 7, A (in their 20s) had a low gloss index value at short cutoff wavelengths and a high gloss index value at long cutoff wavelengths. B (in their 40s) had a high gloss index value at short cutoff wavelengths and a low gloss index value at long cutoff wavelengths.

[0061] Using the results of Figures 6 and 7, the shape of the skin surface can be evaluated as follows. If the gloss index value is low when frequency components with wavelengths smaller than the short cutoff value are removed, the surface can be evaluated as having fine texture. If the gloss index value is high when frequency components with wavelengths shorter than the long cutoff value are removed, the skin can be evaluated as smooth with fewer pores and fine wrinkles. If the gloss index value is high when frequency components with wavelengths smaller than the short cutoff value are removed, it can be evaluated as having a low texture. If the gloss index value is low when frequency components with wavelengths smaller than the long cutoff value are removed, it can be evaluated that the skin has many pores and fine wrinkles and is not smooth.

[0062] Fig. 8 is a diagram for explaining principal component analysis according to one embodiment of the present invention. As described above, in one embodiment of the present invention, evaluation can be performed using the second principal component PC2 extracted by performing principal component analysis on the cutoff value and gloss index value. Note that the cutoff value on the horizontal axis of the left graph in Fig. 8 is expressed in µm as a common logarithm (base 10), and the cutoff value on the horizontal axis of the center graph in Fig. 8 is expressed in µm on a logarithmic scale.

[0063] The left graph in FIG. 8 shows the gloss index value when frequency components having wavelengths smaller than each cutoff value are removed.

[0064] The graph in the center of Figure 8 shows the coefficients at each cutoff value for PC1 and PC2, which are the results of principal component analysis (i.e., extracting the elements that make up the spectrum of reflected light). The first principal component, PC1, has a contribution rate of 80% or more and is the baseline obtained in Monte Carlo calculations. The second principal component, PC2, has a contribution rate of 11%, and reflects the texture and overall smoothness of the skin.

[0065] The first principal component PC1 has a contribution rate of over 80%, but this is due to the inevitable increase in gloss index value caused by the surface becoming smoother as the cutoff value increases, and does not represent the characteristics of the skin surface shape. On the other hand, the second principal component PC2 has a contribution rate of 11%, but has a minimum value near a small cutoff value corresponding to the size of the skin texture and increases at large cutoff values corresponding to the overall skin shape. This means that a high score (factor score, principal component score) for the second principal component PC2 indicates a clearer texture and a smoother overall skin shape. In other words, it was found that the score (factor score, principal component score) for the second principal component PC2 can be used to evaluate the skin texture and overall smoothness of subject 30's skin.

[0066] 8, it was found that the skin texture of the subject 30 can be evaluated based on the gloss index value in the region on the shorter wavelength side of the extreme point (e.g., the minimum point) of the second principal component PC2 in the cutoff wavelength-gloss index value diagram. It was also found that the overall smoothness of the skin of the subject 30 can be evaluated based on the gloss index value in the region on the longer wavelength side of the extreme point (e.g., the minimum point) of the second principal component PC2 in the cutoff wavelength-gloss index value diagram.

[0067] The graph on the right of Figure 8 shows the changes in PC1 and PC2 over an 8-week period when using a serum containing hyaluronic acid, and the changes in PC1 and PC2 over an 8-week period when using a serum without hyaluronic acid. When using a serum containing hyaluronic acid, the score for PC2 increased.

[0068] Fig. 9 is an example of a screen showing the evaluation results of the skin surface shape according to one embodiment of the present invention. As shown in Fig. 9, a screen for presenting the evaluation results of the degree of skin irregularity, skin texture, and overall skin smoothness based on the skin surface shape to a user such as a subject 30 or a beauty consultant is displayed on the user terminal 20 or the like.

[0069] FIG. 10 is a diagram for explaining the improvement of the gloss index value according to an embodiment of the present invention. Specifically, it shows the difference in the gloss index value at each cut-off wavelength when using a beauty liquid containing hyaluronic acid (the value obtained by subtracting the gloss index value before using the beauty liquid from the gloss index value after using the beauty liquid), and the difference in the gloss index value at each cut-off wavelength when using a beauty liquid not containing hyaluronic acid (the value obtained by subtracting the gloss index value before using the beauty liquid from the gloss index value after using the beauty liquid).

[0070] As shown in FIG. 10, for the beauty liquid containing hyaluronic acid, at shorter cut-off wavelengths, the gloss index value decreases compared to before using the beauty liquid, and at longer cut-off wavelengths, the gloss index value increases compared to before using the beauty liquid, as compared with the beauty liquid not containing hyaluronic acid.

[0071] FIG. 11 is a diagram for explaining the improvement of the gloss index value according to an embodiment of the present invention. Specifically, it shows the gloss index value at each cut-off wavelength when using a beauty liquid containing hyaluronic acid for 8 weeks, and the gloss index value at each cut-off wavelength when using a beauty liquid not containing hyaluronic acid for 8 weeks.

[0072] As shown in FIG. 11, when using a beauty liquid containing hyaluronic acid, at shorter cut-off wavelengths, the gloss index value decreases (that is, the texture is improved), and at longer cut-off wavelengths, the gloss index value increases (that is, the surface of the skin is smooth).

[0073] Hereinafter, embodiments of each process will be described.

[0074] [Measurement of the shape of the skin surface] To measure the shape of the skin surface, a replica of the skin (for example, a replica made of silicone) may be used, or the actual object may be used. Also, any three-dimensional shape measurement method such as a confocal microscope, a laser microscope, a white light interference microscope, a projection method, etc. may be used. The size of the measurement target is preferably, for example, 1 mm square or more and 4 mm square or more (for example, 5 mm square). Also, the sampling interval of the measurement target is preferably, for example, 64 μm or less and 8 μm or less (for example, 2.75 μm).

[0075] [Extraction of frequency components belonging to each frequency band] The extraction of the frequency components belonging to each frequency band is not limited to the extraction by the cut-off values of frequency and wavelength using the above-described filters (for example, a low-pass filter, a high-pass filter), and may be extraction by frequency using Fourier transform, extraction by frequency using Fourier series, extraction by scale using wavelet transform, etc. For example, the cut-off value of the wavelength is preferably 32 μm to 2000 μm (for example, 10 μm to 1024 μm).

[0076] [Derivation of the value of the index related to the shape of the skin surface] The value of the index related to the shape of the skin surface is not limited to the above-described gloss index value, and may be Ra, P-V, Rp / Rv, RMS, Rz, Δa, power, absolute value of amplitude, height data (when AI (artificial intelligence) evaluates the shape of the skin surface), parameters of JIS B 0601, etc.

[0077] [Analysis of the value of the index related to the shape of the skin surface in each frequency band] The analysis of the value of the index regarding the shape of the skin surface in each frequency band is not limited to the above-described principal component analysis, and any multivariate analysis such as multiple regression analysis may be used, or AI (artificial intelligence) may be used (specifically, a learning model is generated by training using the result of evaluating the shape of the skin surface as teacher data, and the height data in each frequency band is input to the learning model to output the degree of unevenness of the skin, the texture of the skin, the overall smoothness of the skin, etc., thereby evaluating the shape of the skin surface).

[0078] <Hardware Configuration> FIG. 12 is a block diagram showing an example of the hardware configuration of the skin surface shape evaluation device 10 and the user terminal 20 according to an embodiment of the present invention.

[0079] The skin surface shape evaluation device 10 and the user terminal 20 can include a control unit 1001, a main memory unit 1002, an auxiliary storage unit 1003, an input unit 1004, an output unit 1005, and an interface unit 1006. Each will be described below.

[0080] The control unit 1001 is a processor (for example, a CPU (Central Processing Unit), a GPU (Graphics Processing Unit), etc.) that executes various programs installed in the auxiliary storage unit 1003.

[0081] The main memory unit 1002 includes a non-volatile memory (ROM (Read Only Memory)) and a volatile memory (RAM (Random Access Memory)). The ROM stores various programs, data, etc. necessary for the control unit 1001 to execute various programs installed in the auxiliary storage unit 1003. The RAM provides a work area that is expanded when various programs installed in the auxiliary storage unit 1003 are executed by the control unit 1001.

[0082] The auxiliary storage unit 1003 is an auxiliary storage device that stores various programs and information used when the various programs are executed.

[0083] The input unit 1004 is an input device through which the operator of the skin surface shape evaluating device 10 and the user terminal 20 inputs various instructions to the skin surface shape evaluating device 10 and the user terminal 20 .

[0084] The output unit 1005 is an output device that outputs the internal states of the skin surface shape evaluation device 10 and the user terminal 20, etc.

[0085] The interface unit 1006 is a communication device for connecting to a network and communicating with other devices.

[0086] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the specific embodiments described above, and various modifications and variations are possible within the scope of the gist of the present invention. [Explanation of symbols]

[0087] 1. Skin surface shape evaluation system 10. Skin surface shape evaluation device 20 User terminal 30 Target Audience 101 Skin surface shape acquisition section 102 Frequency component extraction unit 103 Index value derivation unit 104 Evaluation Department 105 Screen generation section 201 Skin surface shape acquisition section 202 Skin surface shape transmitter 203 Evaluation Reception Unit 204 Display section 1001 control section 1002 Main memory 1003 Auxiliary storage unit 1004 Input section 1005 Output section 1006 Interface section

Claims

1. Obtain measurement data indicating the measurement result of the shape of the surface of the subject's skin, Generate a plurality of extracted data composed of frequency components belonging to each of a plurality of frequency ranges among the frequency components constituting the measurement data, For each of the extracted data, derive a value of an index regarding the shape of the surface of the skin, A method for evaluating the shape of the surface of the skin based on the value of the index for each of the derived extracted data.

2. Generating the plurality of extracted data includes: For each of a plurality of threshold values, extracting frequency components having a frequency smaller than each threshold value from the frequency components constituting the measurement data, The method according to claim 1, comprising: The method according to claim 1.

3. Generating the plurality of extracted data includes: Outputting, for each of a plurality of threshold values, information indicating a waveform in which frequency components having a wavelength smaller than the threshold value are removed from the frequency components constituting the waveform indicating the shape of the surface of the skin, The method according to claim 1, comprising: The method according to claim 1.

4. The evaluation according to claim 1 includes evaluating using variables extracted by performing multivariate analysis on the index for each of the extracted data.

5. The evaluation according to claim 1 includes evaluating the texture of the subject's skin based on one or more waveform components having a wavelength of 600 μm or less when the waveform indicating the shape of the surface of the skin is represented as a superposition of a plurality of waveform components having different wavelengths.

6. The evaluation according to claim 1 includes evaluating the overall smoothness of the subject's skin based on one or more waveform components having a wavelength of 500 μm or more when the waveform indicating the shape of the surface of the skin is represented as a superposition of a plurality of waveform components having different wavelengths.

7. The index regarding the shape of the surface of the skin is surface reflection on the surface of the skin, the method according to claim 1.

8. A skin surface shape acquisition unit that acquires measurement data indicating the measurement result of the shape of the surface of the subject's skin, A frequency component extraction unit that generates a plurality of extracted data composed of frequency components belonging to each of a plurality of frequency ranges among the frequency components constituting the measurement data, An index value derivation unit that derives a value of an index regarding the shape of the surface of the skin for each of the extracted data, An evaluation unit that evaluates the shape of the surface of the skin based on the value of the index for each of the derived extracted data A skin surface shape evaluation system comprising the same.

9. A program for causing a skin surface shape evaluation system to function as: a skin surface shape acquisition unit that acquires measurement data indicating a measurement result of the shape of the surface of a subject's skin; a frequency component extraction unit that generates a plurality of extraction data each constituted by frequency components belonging to each of a plurality of frequency ranges among the frequency components constituting the measurement data; an index value derivation unit that derives a value of an index regarding the shape of the surface of the skin for each of the extraction data; and an evaluation unit that evaluates the shape of the surface of the skin based on the derived values of the index for each of the extraction data.

10. An acquisition unit that acquires measurement data indicating a measurement result of the shape of the surface of a subject's skin; and a screen generation unit that generates a screen for presenting to a user a result of evaluating the degree of unevenness of the skin, the texture of the skin, and the overall smoothness of the skin based on the shape of the surface of the skin. A skin surface shape evaluation apparatus comprising the same.

Images