Skin evaluation method, skin evaluation device and program

Abstract

The skin evaluation method includes acquiring information of light emitted from the inside of skin irradiated with light, and evaluating the state of a specified depth of the skin using information of light of a specified wavelength in the light emitted from the inside of the skin.

Description

Technical Field

[0001] The present invention relates to a skin evaluation method, a skin evaluation device and a program. Background Art

[0002] As a skin evaluation method, there is a method of irradiating light onto the skin and utilizing the information of the returned light. For example, Patent Document 1 describes the following method, which is a skin condition evaluation method using the following skin image data, receiving the reflected light of the linear or point light projected onto the skin of the subject and reflected by the surface and the inside of the skin, thereby obtaining skin image data corresponding to the evaluation object area of ​​the skin, wherein skin image data consisting of a collection of images of the skin area at a specified distance from the projection position of the light on the skin is obtained, and the skin condition of the evaluation object area is evaluated based on the spatial distribution of the reflected light on the skin surface and inside the skin represented by the distribution value of the reflected light intensity at each specified distance calculated from the skin image data. The skin condition evaluated by the method described in Patent Document 1 is specifically the transparency of the skin, which is the impression of the appearance or the beauty of the skin recognized by human vision.

[0003] [Prior art literature]

[0004] [Patent Literature]

[0005] [Patent Document 1] Patent No. 6029379 Summary of the invention

[0006] [Problems to be solved by the invention]

[0007] In recent years, it has become necessary to evaluate skin conditions in more detail. Therefore, for example, analysis and evaluation of skin tissue conditions have become important. However, such analysis of skin tissue conditions often requires the use of large-scale equipment with precision equipment, which becomes a burden for experimenters.

[0008] In view of the above circumstances, an object of one embodiment of the present invention is to provide a simple method capable of evaluating skin conditions in more detail.

[0009]

Methods to solve the problem

[0010] In order to solve the above-mentioned problems, a skin evaluation method according to one embodiment of the present invention includes obtaining information of outgoing light from inside the skin irradiated with light, and evaluating the state of a specified depth of the skin using information of light of a specified wavelength in the outgoing light from inside the skin.

[0011] [Effects of the invention]

[0012] According to one embodiment of the present invention, a simple method can be provided for evaluating skin conditions in more detail. BRIEF DESCRIPTION OF THE DRAWINGS

[0013]

Figure 1

[0014]

Figure 2

[0015]

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[0016]

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[0018]

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[0019]

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[0020]

Figure 8

[0021]

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[0022]

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[0023]

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[0024]

Fig.12

[0025] <Skin evaluation method>

[0026] A skin evaluation method based on an embodiment of the present invention obtains information about outgoing light from the inside of the skin irradiated with light, and uses information about light of a specified wavelength in the outgoing light from the inside of the skin to evaluate the state of the skin at a specified depth. The evaluation obtained according to this embodiment is an evaluation for cosmetic purposes. In addition, in this specification, "light of a specified wavelength" refers to light with a single wavelength or light with a specified wavelength range (wavelength width). In addition, it can also be light synthesized by two or more lights with different specified single wavelengths, or it can be light synthesized by two or more lights with different specified wavelength ranges.

[0027] When light is irradiated to the skin, the irradiated light exhibits various behaviors due to the translucency of the skin. For example, it may be light reflected from the skin surface in the direction opposite to the irradiation direction (referred to as "surface reflected light" or "mirror reflected light"), light reflected from the skin surface in various directions other than the irradiation direction due to the unevenness of the skin surface (referred to as "diffuse reflected light" or "surface diffuse reflected light"), or light absorbed inside the skin (below the skin surface), or light scattered inside the skin (below the skin surface) and emitted from the skin surface. Among these lights, light scattered inside the skin and emitted from the skin surface may be referred to as "subsurface scattered light", "internal scattered light", "internal reflected light", "internal diffused light", "diffused light", "internal transmission light", "light inside the skin", etc., but in this specification, it is referred to as "outgoing light from the inside of the skin" or "outgoing light from the inside". In addition, even if light is incident on the skin, light scattered inside the skin that is not emitted from the skin surface to the outside is considered as light absorbed by the skin and is not included in the "outgoing light from the inside of the skin". In addition, in this specification, "surface reflected light" and "diffuse reflected light" are sometimes collectively referred to as "reflected light on the skin surface", and this "reflected light on the skin surface" and "outgoing light from the inside of the skin" are collectively referred to as "total reflected light".

[0028] The present embodiment is a skin evaluation method using the above-mentioned information of the emitted light from inside the skin. The inventors have discovered that the depth of penetration into the skin tissue is different based on the wavelength of the emitted light from inside the skin, and further, the state of the skin tissue at a specified depth of the skin is reflected by the information of the emitted light from inside the skin of a specified wavelength. The present invention is based on such a discovery. Here, the state of the skin at a specified depth refers to the state of a specified position contained in the skin tissue, or the state of a specified layer contained in the skin tissue. In addition, the light information includes image data.

[0029] Skin tissue has a structure composed of a plurality of layers, and each of these layers has a predetermined organization, composition, or property, and has a predetermined function. In this embodiment, the state of one or more layers constituting the skin tissue can be evaluated. Figure 1 This is a schematic diagram showing skin tissue (skin structure). Figure 1 As shown, the skin is roughly divided into, and has epidermis, dermis and subcutaneous tissue in sequence from the side close to the skin surface. In this model, the epidermis contains a stratum corneum as the outermost layer, and the following is the granular layer, the spinous layer (granular layer and / or the spinous layer) and the basal layer (basement membrane). The dermis contains the papillary layer, the subpapillary layer, the upper capillary network layer, the reticular layer and the lower capillary network layer in sequence from the side close to the skin surface. The subcutaneous tissue is below the lower capillary network layer. Therefore, in this embodiment, for example, more than one of the epidermis and dermis can be evaluated, or in more detail, the state of more than one layer contained in the epidermis and / or more than one layer contained in the dermis can be evaluated.

[0030] The present inventors have discovered that information about blue light and / or green light in the outgoing light from the inside of the skin irradiated by light is highly correlated with the state of the epidermis in the skin tissue. An evaluation method according to one embodiment of the discovery includes evaluating the state of the epidermis using information about blue light and / or green light in the outgoing light from the inside of the skin. In particular, information about blue light in the outgoing light from the inside of the skin irradiated by light is highly correlated with the state of the stratum granulosum and / or stratum spinosum in the epidermis, and therefore, a skin evaluation method according to one embodiment of the present invention includes evaluating the state of the stratum granulosum and / or stratum spinosum using information about blue light in the outgoing light from the inside of the skin. In addition, information about green light in the outgoing light from the inside of the skin irradiated by light is highly correlated with the state of the basal layer in the epidermis, and therefore, a skin evaluation method according to one embodiment of the present invention includes evaluating the state of the basal layer using information about green light in the outgoing light from the inside of the skin.

[0031] In addition, according to one embodiment of the skin evaluation method, information of all reflected light from the skin irradiated with light (light information including information of reflected light on the skin surface and information of emitted light from the inside of the skin) is also obtained, and information of light of a specified wavelength in the emitted light from the inside of the skin can also be used. For example, information of blue light in the total reflected light and information of blue light in the emitted light from the inside of the skin can be used to evaluate the state of the stratum corneum. In this case, the difference between information of blue light in the total reflected light and information of blue light in the emitted light from the inside of the skin is used.

[0032] Furthermore, the inventors have found that the information about red light in the outgoing light from the inside of the skin irradiated by light is highly correlated with the state of the dermis in the skin tissue. An evaluation method according to one mode based on this discovery includes evaluating the state of the dermis using the information about red light in the outgoing light from the inside of the skin. In addition, in the evaluation of the state of the dermis, in addition to the information about red light in the outgoing light from the inside of the skin, the information about green light in the outgoing light from the inside of the skin can also be used. At this time, the difference between the information about red light in the outgoing light from the inside of the skin and the information about green light in the outgoing light from the inside of the skin can be used.

[0033] In the past, methods for analyzing and evaluating the state of skin tissue include photoacoustic microscopy, confocal microscopy, multiphoton microscopy, optical coherence tomography (OCT), etc. However, such methods require large equipment, and the measurement takes time and effort, so they cannot be easily used. In contrast, the present embodiment uses information from the outgoing light from the inside of the skin irradiated with light, and the information of the outgoing light from the inside required for evaluation can be obtained by a camera, etc., so detailed evaluation of the skin can be performed more easily than with existing technologies.

[0034] Figure 2 1 is a flowchart showing a specific example of the evaluation method according to the present embodiment. Figure 2 As shown, the evaluation method according to the present embodiment more specifically includes a step of irradiating light onto the skin of an experimenter (S1), a step of separating image data of outgoing light from inside the skin from image data of all reflected light (S2), a step of generating spectral image data of a specified wavelength from the image data (S3), a step of calculating an index using the image data (S4), and a step of evaluating the state of a specified layer in the skin tissue based on the index (S5).

[0035] The light source used in the light irradiation step (S1) is preferably a light source that can irradiate light including visible light, for example, a white light source is preferably a white light source. A white light source continuously has a broad spectrum wavelength range that includes visible light wavelengths, and therefore, can be used to obtain information on the status of various depth positions within the skin tissue, or the evaluation of the status of various layers within the skin tissue. In addition, if a specified layer to be evaluated within the skin tissue (a depth position to be evaluated within the skin tissue) is predetermined, the light source may include a specified wavelength that reflects the status of the specified layer to be evaluated of the skin tissue (the status of the depth position of the skin tissue). In addition, the light irradiated from the light source is preferably light that irradiates in a narrow range in the evaluation object area, such as linear, point-shaped or sinusoidal light. Linear or point-shaped light is particularly preferred because the calculation is not complicated.

[0036] Regarding the step (S2) of separating the image data of the outgoing light from the inside of the skin from the image data of all the reflected light from the skin surface, refer to Figure 3 During separation, the image data of the skin is acquired by a camera (video recording). As the camera used to acquire the image data, an RGB camera, a light field camera, a spectral camera, a hyperspectral camera, etc. can be used. During video recording, a pattern including an irradiated area and a non-irradiated area is projected onto the skin area to be evaluated (evaluation object area). Figure 3 (a)). Such a pattern including irradiated areas and non-irradiated areas can be formed by, for example, projecting an image with white (= irradiated areas) and black (= non-irradiated areas) arranged alternately from a projector, and placing a template with light-transmitting areas and opaque areas arranged alternately in strips at the irradiation port of the projector. Figure 3 As shown in (a), the following state can be formed, where a pattern including an irradiated area and a non-irradiated area is projected onto the face of the experimenter.

[0037] Generally, light irradiated to the evaluation target area is reflected by the skin surface, or is transmitted through the skin surface and scattered inside the skin, and then emitted from the skin surface to the outside. Figure 3 (b) Represents the behavior of light relative to the skin. Figure 3 Arrow 1 in (b) is the irradiated light (light irradiated from the light source to the skin). Arrow 2 is the light specularly reflected on the irradiated area, and arrow 3 is the light diffusely reflected on the surface of the irradiated area. Arrow 4 is the light emitted to the outside of the skin after being scattered inside the skin (light that enters the skin, detours inside the skin, and then emits), that is, the emitted light from the inside of the skin. The light indicated by arrow 5 is the light absorbed inside the skin and is not emitted to the outside.

[0038] The light emitted from the inside is emitted from both the irradiated area and the non-irradiated area. The light emitted from the non-irradiated area is only the light emitted from the inside. Therefore, by measuring the intensity of the light emitted from the non-irradiated area, the information of the light emitted from the inside can be obtained locally from the evaluation object area. Then, the above pattern is slid ( Figure 3 (c)) Project a non-irradiated area onto the area in the evaluation object area that becomes the irradiated area, and measure the light intensity of the outgoing light from the inside in the newly projected non-irradiated area. Thus, the intensity of the outgoing light from the inside can be measured in the entire evaluation object area, and two-dimensional image data of the outgoing light from the inside of the skin can be obtained. Furthermore, by measuring the light intensity of the reflected light in the irradiated area in the evaluation object area, the light intensity of all reflected light (i.e., the sum of the reflected light on the skin surface and the outgoing light from the inside of the skin) can be measured in the entire evaluation object area, and two-dimensional image data of all reflected light can be obtained. The image size is preferably greater than 20 pixels × 20 pixels.

[0039] In addition, when the above pattern is a stripe pattern as shown in the figure, the width of the non-irradiated area can be more than 0.1mm and less than 10mm, and the width of the irradiated area can be more than 0.1mm and less than 3mm. In addition, the pattern does not have to be stripe-shaped, and if it is a pattern in which the irradiated area and the non-irradiated area are repeated on the surface, it can also be a grid pattern, etc.

[0040] Thus, in the image data separation step (S2), when recording, the image data of all reflected light, that is, the image data of the outgoing light from the inside of the skin can be separated from the image data including the image data of the reflected light on the skin surface and the image data of the outgoing light from the inside of the skin. In other words, the image data of the reflected light on the skin surface and the image data of the outgoing light from the inside of the skin can be separated from the image data of all reflected light. Therefore, in step S2 of the present embodiment, one or more of the image data of all reflected light, the image data of the reflected light on the skin surface, and the image data of the outgoing light from the inside of the skin can be obtained.

[0041] here, Figure 4 In the example of image data of the outgoing light from the inside of the skin obtained in the separation step (S2) is represented as initial image data Img-0. The initial image data Img-0 includes data of the light intensity of visible light (360 to 840 nm) in the evaluation target area. In other words, the initial image data Img-0 is an image expressed by the intensity of the outgoing light from the inside including the visible light.

[0042] In the spectroscopic image data generating step (S3), spectroscopic image data of a specified wavelength is generated from the image data obtained in the image data separating step (S2). In the spectroscopic image data generating step (S3), spectroscopic image data can be generated from any image data obtained in the image data separating step (S2). More specifically, spectroscopic image data can be generated from one or more of the image data of all reflected light, the image data of reflected light on the skin surface, and the image data of emitted light from the inside of the skin obtained in the image data separating step (S2). The spectroscopic image data is image data containing information of light of a specified wavelength (information of light intensity). In addition, the spectroscopic image data of a specified wavelength obtained in the spectroscopic image data generating step (S3) can be spectroscopic image data of a single wavelength, or can be spectroscopic image data of a specified wavelength range (wavelength width), can be spectroscopic image data of light synthesized by two or more different lights of a specified single wavelength, or can be spectroscopic image data of light having two or more different specified wavelength ranges.

[0043] Figure 4 FIG. 2 shows an example of generating spectroscopic image data of a designated wavelength from image data of light emitted from the inside of the skin (initial image data Img-0). Figure 4 This is an example of generating spectral image data when using an RGB camera. Figure 4 As shown, image data Img-B of blue light (wavelength 380-500nm), image data Img-G of green light (wavelength 500-600nm), and image data Img-R of red light (wavelength 600-720nm) can be generated from initial image data Img-0. Furthermore, by using a spectral camera or a hyperspectral camera, spectral image data of light in an arbitrary wavelength range can be generated. Spectral image data of a specified wavelength can also be generated from image data of all reflected light in the same manner.

[0044] Furthermore, in the index calculation step (S4), an index for skin evaluation is calculated based on at least one of the spectroscopic image data of the specified wavelength. The index may be an index of the overall size of light intensity or an index of distribution. In addition, after the light intensity is converted into absorbance by logarithmic transformation, an index of the overall size or an index of distribution may be calculated. For example, it may be one or more statistics of the average value, maximum value, minimum value, median value, integral value, total value, standard deviation, variance, skewness, and kurtosis of the light intensity in the evaluation object area.

[0045] In addition, in the index calculation step (S4), the index calculation based on the spectroscopic image data includes calculating the index using more than two spectroscopic image data. The more than two spectroscopic image data may be, for example, two spectroscopic image data of outgoing light from the inside of the skin having different specified wavelengths, or may be spectroscopic image data of all reflected light having a specified wavelength and spectroscopic image data of outgoing light from the inside of the skin having a specified wavelength that is the same as the specified wavelength. Or it may be spectroscopic image data of all reflected light having a specified wavelength and spectroscopic image data of outgoing light from the inside of the skin having a specified wavelength that is different from the specified wavelength. When calculating the index using such more than two spectroscopic image data, for example, the index may be calculated based on finding the difference, ratio, etc. of the two spectroscopic image data. At this time, difference image data, ratio image data, etc. may be generated, and the index may be calculated based on the difference image data, ratio image data, etc. That is, the index calculation based on the spectroscopic image data may include calculating the index based on the difference image data and ratio image data obtained from more than two spectroscopic image data. An example of the difference image data is difference image data obtained by subtracting spectral image data of the light emitted from the inside of the skin at the same designated wavelength from spectral image data of all reflected light at the same designated wavelength.

[0046] The obtained index is used in the step (S5) of evaluating the state of the designated layer of the skin. In order to evaluate the state of the designated layer of the skin, the relationship between the index calculated based on the spectroscopic image data of the designated wavelength and the state of the designated layer in the skin tissue is pre-calculated and stored as a database. In such a pre-calculated relationship, the index calculated based on the spectroscopic image data of the designated wavelength obtained through steps S1 to S4 for the experimenter who wants to evaluate the skin is applied, thereby determining and evaluating the state of the designated layer in the skin tissue of the above-mentioned experimenter. Therefore, for example, in the evaluation step (S5), the relationship between the index calculated based on the spectroscopic image data corresponding to the outgoing light from the inside of the skin at the designated wavelength and the state of the designated layer in the skin tissue is pre-calculated, and in this relationship, the index calculated based on the spectroscopic image data of the designated wavelength obtained through steps S1 to S4 for the experimenter who wants to evaluate the skin is applied to determine and evaluate the state of the designated layer in the skin tissue. In addition, as described above, the above-mentioned spectroscopic image data may include spectroscopic image data generated from the image data of all reflected light and spectroscopic image data generated from the image data of the outgoing light from the inside of the skin. In addition, as described above, when an indicator is obtained based on difference image data or ratio image data obtained from more than two spectral image data, the relationship between the indicator calculated based on such difference image data or ratio image data and the state of a specified layer in the skin tissue can be obtained in advance, and in this relationship, it is applicable to determine and evaluate the state of the specified layer in the skin tissue based on the indicator calculated based on the difference image data or ratio image data obtained from the spectral image data of a specified wavelength through steps S1 to S4 for an experimenter who wants to evaluate the skin.

[0047] In the evaluation step (S5), the state of the designated skin layer to be evaluated may be, for example, the state of the epidermis or the state of the dermis. The state of the epidermis includes at least one of the state of the stratum corneum, the state of the stratum granulosum and / or the stratum spinosum, and the state of the basement membrane.

[0048] <Skin evaluation device>

[0049] Figure 5 FIG. 2 shows a skin evaluation system 1 used in the skin evaluation method according to the present embodiment. Figure 5 As shown, the skin evaluation system 1 includes a skin evaluation device 10 , a camera 20 , and a light source 30 .

[0050] The skin evaluation device 10 can be a computer for evaluating the optical properties of the skin, and can execute the above-mentioned steps S2 to S5. That is, the skin evaluation device 10 uses the image photographed by the camera 20 to obtain information about the light irradiated from the light source 30, incident into the skin, circling in and out of the skin surface, and then emitting from the skin surface (outgoing light from the inside). In addition, spectral image data of a specified wavelength can be generated from the image data, and an index of the outgoing light from the inside of the specified wavelength in the evaluation object area can be calculated. Furthermore, based on the calculated index, the state of the specified layer in the skin tissue of the evaluation object area can be determined and evaluated by using the relationship between the index of the outgoing light from the inside of the specified wavelength and the state of the specified layer in the skin tissue that has been previously obtained. The skin evaluation device 10 can be a personal computer, a tablet terminal, a smart phone, etc.

[0051] The camera 20 is a device for photographing the skin, and may be, for example, the above-mentioned RGB camera, spectral camera, hyperspectral camera, light field camera, etc. The image photographed by such a camera 20 is an image displayed by the intensity of the internal reflected light, and the emitted light from the inside is divided into a plurality of wavelength ranges, including images of the respective wavelength ranges.

[0052] like Figure 5 In the example shown, the skin evaluation device 10, the camera 20, and the light source 30 are described as different devices, but in practice, at least two of the skin evaluation device 10, the camera 20, and the light source 30 may be the same device. For example, when the camera 20 and the skin evaluation device 10 are installed in a terminal such as a smartphone, the user may take a skin image of his or her own face with the built-in camera of the smartphone and perform the evaluation.

[0053] Figure 6 FIG. 1 is a functional block diagram of the skin evaluation device 10. Figure 6 As shown, the skin evaluation device 10 may include an image acquisition unit (information acquisition unit) 101, a calculation unit 102, and an evaluation unit 103. The skin evaluation device 10 may function as the image acquisition unit 101, the calculation unit 102, and the evaluation unit 103 by executing a program.

[0054] The image acquisition unit 101 acquires, through the camera 20, an image showing the intensity of the outgoing light from the inside of the skin in the evaluation target area of ​​the skin irradiated by the light from the light source 30. The image acquisition unit 101 can acquire information on the outgoing light from the inside of the evaluation target area from the above-mentioned image acquired from the camera 20, more specifically, information on the intensity of each wavelength or wavelength range of the outgoing light from the inside (for example, each value of RGB of each pixel). The image acquisition unit 101 can also generate or extract spectral image data of a specified wavelength from the acquired image of the outgoing light from the inside (information on the outgoing light from the inside). In addition, the image acquisition unit 101 can also perform certain processing on the acquired image data or spectral image data, such as noise reduction processing, sharpening processing, correction processing, etc.

[0055] The calculation unit 102 can calculate an index about the outgoing light from the inside at the specified wavelength or the outgoing light from the inside in the specified wavelength range based on the obtained spectral image data of the specified wavelength. The index can be an index about the overall size of the light intensity or an index about the distribution. The light intensity can also be converted into absorbance and then the index about the overall size or the index about the distribution can be calculated.

[0056] The evaluation unit 103 evaluates the skin based on the index calculated by the calculation unit 102. For example, the evaluation unit 103 can evaluate the state of the specified layer in the skin tissue based on the relationship between the index of the outgoing light from the inside with a specified wavelength and the state of the specified layer in the skin tissue, which is previously obtained and stored in the skin evaluation device 10.

[0057] <Hardware Structure>

[0058] Figure 7 1 is a block diagram showing an example of the hardware configuration of the skin evaluation device 10 according to one embodiment of the present invention.

[0059] The skin evaluation device 10 includes a CPU (Central Processing Unit) 1001, a ROM (Read Only Memory) 1002, and a RAM (Random Access Memory) 1003. The CPU 1001, the ROM 1002, and the RAM 1003 form a so-called computer.

[0060] In addition, the skin evaluation device 10 may include an auxiliary storage device 1004, a display device 1005, an operation device 1006, an I / F (interface) device 1007, and a drive device 1008. In addition, the hardware components of the skin evaluation device 10 are connected to each other via a bus B.

[0061] The CPU 1001 is a computing device that executes various programs installed in the auxiliary storage device 1004 .

[0062] ROM 1002 is a nonvolatile memory. ROM 1002 functions as a main storage device, and stores various programs and data required for CPU 1001 to execute various programs installed in auxiliary storage device 1004. Specifically, ROM 1002 functions as a main storage device, and stores boot programs such as BIOS (Basic Input Output System) and EFI (Extensible Firmware Interface).

[0063] The RAM 1003 is a volatile memory such as a DRAM (dynamic random access memory) or an SRAM (static random access memory) and functions as a main storage device, providing a work area in which various programs installed in the auxiliary storage device 1004 are executed by the CPU 1001 .

[0064] The auxiliary storage device 1004 is an auxiliary storage device that stores various programs and information used when the various programs are executed.

[0065] The display device 1005 is a display device that displays the internal state of the skin evaluation device 10 and the like.

[0066] The operation device 1006 is an input device for the administrator of the skin evaluation device 10 to input various instructions to the skin evaluation device 10 .

[0067] The I / F device 1007 is a communication device for connecting to a network and communicating with the skin evaluation device 10 .

[0068] The drive device 1008 is a device for setting the storage medium 1009. The storage medium 1009 mentioned here includes a medium that records information optically, electrically or magnetically, such as a CD-ROM, a floppy disk, a magneto-optical disk, etc. In addition, the storage medium 1009 includes a semiconductor memory that records information electrically, such as an EPROM (erasable programmable read-only memory), a flash memory, etc.

[0069] In addition, various programs installed in the auxiliary storage device 1004 may be installed, for example, by setting the allocated storage medium 1009 in the drive device 1008 and reading various programs recorded in the storage medium 1009 through the drive device 1008. Alternatively, various programs installed in the auxiliary storage device 1004 may be downloaded from the network through the I / F device 1007.

[0070] Hereinafter, embodiments of the present invention will be described in further detail.

[0071] <First embodiment>

[0072] The skin evaluation method according to the first embodiment is a skin evaluation method that obtains information of outgoing light from the inside of the skin irradiated with light, and evaluates the skin condition in the granular layer and / or the spinous layer using information of blue light in the outgoing light from the inside.

[0073] Blue (wavelength 380-500nm) light emitted from the skin mainly in the granular layer and / or spinous layer ( Figure 1 ) is reflected and emitted from the skin surface, and the state of the granular layer and / or the spinous layer can be reflected in the image data of the blue light in the emitted light from the inside of the skin. Therefore, according to this embodiment, for example, the thickness of the epidermis layer, the amount of melanin, etc. can be easily evaluated. For example, by evaluating the amount of melanin, the dullness, uneven color (including spots, freckles, etc.), sun exposure, etc. of the skin can be evaluated.

[0074] In this embodiment, refer to Figure 2 In the above-mentioned spectral image data generating step (S3), the spectral image data of blue light is generated, and in the index calculating step (S4), the index is calculated using the spectral image data of blue light. Figure 2 The process description shown may be a skin evaluation method, comprising: a step of irradiating light onto the skin of an experimenter (S1), a step of separating image data of outgoing light from inside the skin from image data of all reflected light (S2), a step of generating spectral image data of blue light from image data of outgoing light from inside the skin (S3), a step of calculating an index using the spectral image data of blue light (S4), and a step of evaluating the state of the granular layer and / or the spinous layer based on the index (S5).

[0075] =Application example (Example) of the first embodiment=

[0076] As an application example of the first embodiment, the evaluation of melanin amount is studied. Specifically, skin images of the faces of 24 subjects aged 30 to 39 were taken using an RGB camera. The image data of the outgoing light from the inside of the skin was separated from the obtained image data (image data of all reflected light), and the spectral image data of blue light (wavelength 380 to 500nm) was generated from the image data of the outgoing light from the inside of the skin. The light intensity in the spectral image was converted into absorbance, which was multiplied by the coefficient determined by multivariate regression analysis and used as the melanin index (indicator). On the other hand, the distribution of the overall melanin amount on the face of each subject was measured based on its spectral spectrum using a spectrophotometer, and its average value was used as the "melanin amount" of the subject. Figure 8 Indicates the relationship between melanin index and melanin amount. Figure 8 As shown, it is confirmed that there is a high correlation between the two.

[0077] Therefore, if Figure 8 The relationship shown is calculated in advance, and skin image data is obtained from a subject who wants to evaluate the amount of melanin in the skin. Image data of blue light in the outgoing light from inside the skin is then generated to calculate an index (melanin index). By applying this index to the above-mentioned relationship calculated in advance, the amount of melanin in the subject can be evaluated and estimated.

[0078] <Second embodiment>

[0079] The skin evaluation method according to the second embodiment is a skin evaluation method that obtains information on light emitted from the inside of skin irradiated with light and evaluates the skin condition in the basal layer (basement membrane) using information on green light in the light emitted from the inside.

[0080] Green (wavelength 500-600nm) light emitted from the skin is mainly emitted in the basal layer of the skin tissue ( Figure 1 ) is reflected and emitted from the skin surface, so the state of the basal layer can be reflected in the image data of the green light in the emitted light from the inside of the skin. Therefore, according to this embodiment, for example, reflection from the basal layer, elasticity, etc. can be easily evaluated. By evaluating the basal layer according to this embodiment, the possibility of future deterioration of the skin, the health of the skin, etc. can be evaluated.

[0081] In this embodiment, refer to Figure 2 In the above-mentioned spectral image data generating step (S3), the spectral image data of green light is generated, and in the index calculating step (S4), the index is calculated using the spectral image data of green light. Figure 2 The process description shown may be a skin evaluation method, comprising a step of irradiating light onto the skin of an experimenter (S1), a step of separating image data of outgoing light from inside the skin from image data of all reflected light (S2), a step of generating spectral image data of green light from image data of outgoing light from inside the skin (S3), a step of calculating an index using the spectral image data of green light (S4), and a step of evaluating the state of the basal layer (basement membrane) based on the index (S5).

[0082] <Third embodiment>

[0083] The skin evaluation method according to the third embodiment may be a skin evaluation method that acquires information of light emitted from the inside of the skin irradiated with light and evaluates the skin condition in the dermis using information of red light in the light emitted from the inside.

[0084] The red (wavelength 600-720nm) light emitted from the skin is mainly emitted in the dermis, especially the papillary layer and / or subpapillary layer ( Figure 1 ) is reflected and emitted from the skin surface, so the state of the dermis, especially the papillary layer and / or the subpapillary layer, can be reflected in the image data of the red light emitted from the inside. Therefore, according to this embodiment, for example, collagen density, blood vessel density, the number of capillaries, hemoglobin amount, etc. can be easily evaluated. By evaluating the dermis according to this embodiment, the evaluation of skin color (evaluation of skin color considered to be young), the evaluation of the elasticity of the skin as a whole, inflammation, blood circulation status, etc. can be evaluated.

[0085] In this embodiment, refer to Figure 2 In the above-mentioned spectral image data generating step (S3), the spectral image data of red light is generated, and in the index calculating step (S4), the index is calculated using the spectral image data of red light. Figure 2 The process illustrated may be a skin evaluation method, comprising the step of irradiating light onto the skin of an experimenter (S1), the step of separating image data of outgoing light from inside the skin from image data of all reflected light (S2), the step of generating spectral image data of red light from image data of outgoing light from inside the skin (S3), the step of calculating an index using the spectral image data of red light (S4), and the step of evaluating the state of the dermis, particularly the papillary layer and / or the subpapillary layer, based on the index (S5).

[0086] Furthermore, in the step (S3) of generating spectral image data, in addition to the spectral image data of red light in the outgoing light from the inside of the skin, spectral image data of green light in the outgoing light from the inside of the skin can also be generated. Furthermore, in the step (S4) of calculating an index, in addition to the spectral image data of red light in the outgoing light from the inside of the skin, spectral image data of green light in the outgoing light from the inside of the skin can also be used to calculate the index. At this time, the index can be calculated using the difference image data of the spectral image data of red light in the outgoing light from the inside of the skin and the spectral image data of green light in the outgoing light from the inside of the skin. Thus, the influence of the information of the green light reaching the basal layer can be subtracted from the information of the outgoing light from the inside of the skin, so that the state of the dermis can be evaluated with higher accuracy.

[0087] =Application example (Example) of the third embodiment=

[0088] As an application example of the third embodiment, the evaluation of the hemoglobin amount is studied. In the same manner as the video recording in the application example of the first embodiment, an image of the subject's skin is taken. From the obtained image data (image data of all reflected light), the image data of the outgoing light from the inside of the skin is separated, and then from the image data of the outgoing light from the inside of the skin, spectral image data of red light (wavelength 600-720nm) and spectral image data of green light (wavelength 500-600nm) are generated, and the difference image data of the two spectral image data are obtained. The light intensity in the difference image data is converted into absorbance, multiplied by the coefficient obtained by multivariate regression analysis, and the result is used as hemoglobin (index). On the other hand, the distribution of the hemoglobin amount in the entire face of each subject is measured based on the spectral spectrum obtained by a spectrophotometer, and the average value is used as the "hemoglobin amount" of the subject. Fig. 9 It indicates the relationship between hemoglobin index and hemoglobin amount. Fig. 9 As shown, it can be confirmed that the two have a high correlation.

[0089] Therefore, if Fig. 9 The relationship shown is calculated in advance, and skin image data is obtained from a subject who wants to evaluate the amount of melanin in the skin. Image data of red light in the outgoing light from inside the skin is then generated, and an index (hemoglobin index) is calculated. This index is applied to the above-mentioned relationship calculated in advance, thereby evaluating and estimating the hemoglobin amount of the above-mentioned subject.

[0090] In addition, as a further application example of the third embodiment, the evaluation of collagen volume density is studied. Similar to the evaluation of the hemoglobin amount described above, spectral image data of red light (wavelength 600-720nm) and spectral image data of green light (wavelength 500-600nm) are generated, and the difference image data of the two spectral image data are obtained. The light intensity in the spectral image is converted into absorbance, multiplied by the coefficient obtained by multivariate regression analysis, and used as the collagen volume density index (indicator). On the other hand, the distribution of the overall collagen volume density index on the face of each subject is measured by an acoustic microscope, and the regional average value is used as the "collagen volume density" of the subject. Fig.10 It represents the relationship between collagen volume density index and collagen volume density. Fig.10 As shown, it can be confirmed that the two have a high correlation.

[0091] Therefore, if Fig.10The relationship shown is calculated in advance, and skin image data is obtained from a subject who wants to evaluate the collagen volume density of the skin. Image data of red light in the outgoing light from inside the skin is then generated. Image data of red light and image data of green light are generated according to the situation, and an index (collagen volume density index) is calculated. The index is applied to the above-mentioned relationship calculated in advance, thereby evaluating and estimating the collagen volume density of the above-mentioned subject.

[0092] <Fourth embodiment>

[0093] The skin evaluation method according to the fourth embodiment may be a skin evaluation method that is the same as the skin evaluation method according to the first embodiment in that information of the outgoing light from the inside of the skin irradiated with light is obtained and information of blue light in the outgoing light from the inside is used, but further information of all reflected light from the skin irradiated with light is obtained, and the skin condition in the stratum corneum in the epidermis is evaluated using information of blue light in the all reflected light and information of blue light in the outgoing light from the inside. In this embodiment, the difference between information of blue light in the all reflected light and information of blue light in the outgoing light from the inside is used.

[0094] As mentioned above, the blue light (wavelength 380-500nm) emitted from the skin mainly reaches the granular layer and / or spinous layer ( Figure 1 ) is reflected from the skin surface, and therefore, the blue light in the emitted light from the inside of the skin can reflect the state of the stratum corneum and / or the stratum spinosum. On the other hand, the image data of the blue light in the total reflected light obtained by irradiating the experimenter's skin with light reflects the state of the stratum corneum from the stratum granulosum and / or the stratum spinosum to the upper layer. Therefore, when generating spectroscopic image data of blue light from the image data of total reflected light, and generating difference image data by subtracting the image data of blue light in the reflected light from the image data of blue light in the total reflected light, the state of the stratum corneum is reflected in the difference image data. Therefore, according to the present embodiment, for example, the thickness and transparency of the stratum corneum can be easily evaluated. For example, by being able to evaluate the transparency of the stratum corneum, the dullness, turbidity, metabolism, etc. of the skin can be evaluated.

[0095] In this embodiment, refer to Figure 2 In the above-described spectral image data generation step (S3), spectral image data of blue light is generated from the image data of all reflected light and the image data of light emitted from the inside of the skin, respectively. In the index calculation step (S4), the spectral image data of blue light in all reflected light and the image data of blue light in light emitted from the inside of the skin are used to calculate the index. Therefore, according to the skin evaluation method of this embodiment, if the following steps are followed: Figure 2The process description shown may be a skin evaluation method, comprising a step of irradiating light onto the skin of an experimenter (S1), a step of separating image data of outgoing light from the inside of the skin from image data of all reflected light (S2), a step of generating spectral image data of blue light from the image data of outgoing light from the inside of the skin and a step of generating spectral image data of blue light from the image data of all reflected light, respectively (S3), a step of calculating an index using difference image data of the spectral image data of blue light in the outgoing light from the inside of the skin and the spectral image data of blue light in all reflected light (S4), and a step of evaluating the state of the stratum corneum based on the index (S5).

[0096] =Application example (Example) of the fourth embodiment=

[0097] As an application example of the fourth embodiment, the turbidity of the stratum corneum is evaluated. Specifically, skin images of the faces of 134 subjects aged 20 to 79 (22 to 23 subjects in each age group) were photographed using an RGB camera. The image data of the outgoing light from the inside of the skin was separated from the obtained image data (image data of total reflected light), and then spectral image data of blue light (wavelength 380 to 500 nm) was generated from the image data of the outgoing light from the inside of the skin. At the same time, spectral image data of blue light was generated from the image data of total reflected light. Furthermore, the difference image data between the spectral image data of blue light in the total reflected light and the spectral image data of blue light in the outgoing light from the inside of the skin was obtained, and the regional average value of the light intensity in the difference image data was used as the stratum corneum index or turbidity level index (indicator). Fig.11 It represents a graph showing the stratum corneum index relative to the age of the subject. Fig.11 As shown in FIG. 1 , the index (turbidity level) of each layer increases with age, and a tendency to become unfavorable is confirmed. Fig.11 The relationship shown is obtained in advance, and based on the stratum corneum index (index) obtained based on the image data, the approximate age (skin age or stratum corneum age) can be estimated.

[0098] The above-mentioned embodiments can be implemented individually or in combination of two or more. For example, the first embodiment for evaluating the amount of melanin using information of blue light is combined with the third embodiment for evaluating the amount of hemoglobin using information of red light and green light, thereby evaluating inflammation and melanin production caused by ultraviolet rays. In addition, by combining the first to fourth embodiments, a comprehensive evaluation of the skin can be performed, such as determining and evaluating skin age, skin type, etc.

[0099] Fig.12 The results of the comprehensive skin evaluation example are shown in Figure 2. Fig.12In the example shown, the melanin level of the subject's skin is evaluated by the first embodiment, the hemoglobin level and the collagen level are evaluated by the third embodiment, and the stratum corneum level is evaluated by the fourth embodiment. Furthermore, the average of the evaluations of the subjects of the same generation as the subject obtained in advance can be compared. Such a comprehensive skin evaluation can be performed by a relatively simple process such as skin photography.

[0100] Thus, according to the present embodiment, the state of a specified depth in the skin tissue can be evaluated, and thus the potential beauty state of the skin that is not apparent on the outside can be evaluated. Therefore, the obtained evaluation can help determine a beauty policy for fundamentally caring for the skin. For example, based on the evaluation obtained by the above-mentioned skin evaluation method, it is possible to appropriately provide recommendations on beauty methods, makeup methods, lifestyle improvement, etc., cosmetics, care products, beauty foods, etc.

[0101] The present invention has been described above based on specific embodiments, but the above embodiments are given as examples only, and the present invention is not limited to the above embodiments. Various changes, corrections, substitutions, deletions, additions and combinations may be made within the scope of the disclosure of the present invention.

[0102] This application claims priority based on Japanese Patent Application No. 2022-158733 filed on September 30, 2022, the entire contents of which are incorporated herein by reference.

[0103] [Description of Reference Numerals]

[0104] 1 Skin evaluation system

[0105] 10 Skin evaluation device

[0106] 20 Cameras

[0107] 30 Light Source

[0108] 101 Image acquisition unit

[0109] 102 Computing Department

[0110] 103 Evaluation Department

[0111] 1001 CPU

[0112] 1002 ROM

[0113] 1003 RAM

[0114] 1004 Auxiliary storage device

[0115] 1005 Display device

[0116] 1006 Operating device

[0117] 1007 I / F Device

[0118] 1008 Drive unit

[0119] 1009 storage media.

Claims

1. A skin evaluation method, comprising obtaining information on light emitted from the inside of skin irradiated with light, The condition of the skin at a specified depth is evaluated using information on light of a specified wavelength in the light emitted from the inside. 2 . The skin evaluation method according to claim 1 , wherein the light emitted from the inside includes visible light. 3 . The skin evaluation method according to claim 1 , wherein the information on the light of the specified wavelength includes light intensity in the evaluation target area or a statistic of absorbance calculated from the light intensity.

4. The skin evaluation method according to claim 2, comprising: Using the information of the blue light and / or green light in the light emitted from the inside to evaluate the epidermal state, and / or The state of the leather is evaluated using information on red light in the light emitted from the interior.

5. The skin evaluation method according to claim 4, wherein the epidermal state is evaluated as follows: Using the information of the blue light in the light emitted from the interior, the state of the stratum granulosum and / or stratum spinosum is evaluated, Based on the state of the stratum granulosum and / or stratum spinosum, one or more selected from the group consisting of the amount of melanin and the thickness of the epidermis are evaluated.

6. The skin evaluation method according to claim 4, wherein the epidermal state is evaluated as follows: Using the information of green light in the light emitted from the inside, the state of the base layer is evaluated. Based on the state of the base layer, at least one selected from reflected light from the base film and elastic force of the base film is evaluated.

7. The skin evaluation method according to claim 4, wherein the dermis state is evaluated as follows: Using the information of the red light in the light emitted from the inside, the state of the leather is evaluated. Based on the dermis condition, one or more selected from the group consisting of collagen condition, blood vessel condition, and hemoglobin level are evaluated.

8. The skin evaluation method according to claim 4, wherein evaluating the epidermal state comprises: Further obtaining information of all reflected light from the skin illuminated by the light, The state of the stratum corneum is evaluated using the difference between the information of the total reflected light and the information of the green light in the light emitted from the inside. 9 . The skin evaluation method according to claim 8 , wherein at least one selected from stratum corneum transparency and stratum corneum thickness is evaluated based on the stratum corneum state.

10. The skin evaluation method according to claim 7, wherein evaluating the dermis state comprises: The state of the leather is evaluated using the difference between the information of the red light in the light emitted from the interior and the information of the green light in the light emitted from the interior. 11 . The skin evaluation method according to claim 1 , wherein at least one selected from skin age and skin type is determined based on the evaluation of the state of the designated depth of the skin.

12. The skin evaluation method according to claim 1 or 2, wherein obtaining the information of the light emitted from the inside comprises: A pattern including an irradiated area where light is irradiated and a non-irradiated area where light is not irradiated is projected onto the skin area of ​​the evaluation subject, and information on light from the non-irradiated area is acquired.

13. The skin evaluation method according to claim 3, wherein evaluating the state of the skin at a specified depth comprises: Calculating the light intensity in the evaluation target area or the absorbance calculated from the light intensity, including one or more indicators selected from the group consisting of average value, maximum value, minimum value, median value, integrated value, total value, standard deviation, variance, skewness and kurtosis, The condition of the specified depth of the skin is evaluated based on the index.

14. A skin evaluation device, comprising: an information acquisition unit that acquires information of light emitted from the inside of the skin irradiated with light, and The evaluation unit evaluates the state of the skin at a designated depth using information of light of a designated wavelength in the light emitted from the inside.

15. A program for causing a computer to perform the following operations: an information acquisition unit that acquires information of light emitted from the inside of the skin irradiated with light, The evaluation unit evaluates the state of the skin at a designated depth using information of light of a designated wavelength in the light emitted from the inside.

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