JP6960323B2 - How to evaluate skin condition - Google Patents

Description

The present invention relates to a method for evaluating a skin condition.

The skin color changes depending on the amount of melanin, which is the main constituent pigment of skin color, and the amount of hemoglobin, and is an important characteristic from the viewpoint of cosmetics and diagnosis of health condition. In addition, for example, in order to appropriately grasp the whitening condition of the skin and easily diagnose the health condition, it is possible to evaluate the skin color objectively and quantitatively, not sensuously. Since it is necessary, various colorimeters and reflection spectrophotometers have been developed and put on the market, which make it possible to quantify the amount of melanin pigment and the amount of hemoglobin pigment by simply shining light on the skin without collecting the skin. Has been done. These colorimeters and reflection spectrophotometers do not measure the color of the skin, but display it with an index that quantifies the amount of pigment in the skin based on Lambert-Beer's law. It is designed to evaluate the condition.

On the other hand, when the amount of pigment in the skin is quantified and displayed by an index using a colorimeter or a reflection spectrophotometer, the amount of pigment in melanin and the amount of pigment in hemoglobin affect each other, so the index is used. When it increases or decreases, it may be difficult to distinguish whether it is due to an increase in melanin or the like or an increase in hemoglobin due to inflammation or the like. For this reason, by setting an absorbance model from the reflection spectrum of the skin, multiple regression analysis is performed using the extinction coefficient spectrum of the components of the skin, and the amount of the component in the skin is determined. Quantitative methods have been developed (see, for example, Patent Document 1).

Japanese Unexamined Patent Publication No. 11-299743

Journal of Japanese Society of Cosmetic Science Vol.28 No.1 (2004) pp18-22 "Measurement of skin color" by Hirotsugu Takiwaki Feather JW et al. Phys Med Biol 1988: 33: 711-722 Dawson JB et al. Phys Med Biol 1980: 25: 695-709

Here, Lambert-Beer's law states that the absorbance of a dilute solution (the logarithm of the inverse of the transmittance) is proportional to its concentration, and the reflectance is the apparent absorbance (reflectance of). It can be converted to the logarithm of the inverse number) and calculated (see, for example, Non-Patent Document 1).

That is, assuming that the dermis is a white reflector placed under the solution, the reflectance can be substituted by the transmittance × the transmittance, and the pigment concentration (melanin concentration and hemoglobin concentration) can be estimated by measuring the apparent absorbance. Based on the idea. The skin is divided into three layers from the surface: epidermis, dermis, and subcutaneous tissue. From an optical point of view, the color of the skin is determined by the translucent film, the stratum corneum, and the epidermis containing melanin granules. The basal layer (melanin layer), the capillary / small vascular network (hemoglobin layer) at the uppermost layer of the dermis, and the white dermis layer. Approximately 90% of the invading light is transmitted in the stratum corneum, and in the melanin layer and hemoglobin layer, the light is absorbed by each pigment, but there is almost no scattering (diffuse reflection), and the rest is transmitted and mainly scattered in the dermis. It will occur. In the multi-layer model of the skin shown in FIG. 2 in which the stratum corneum is omitted, the reflectance R at a certain wavelength λ has the transmittances of the melanin layer m and the hemoglobin layer h at Tm, Th, and the dermal layer d, respectively. Assuming that the reflectance is Rd, light reciprocates in the melanin layer m and the hemoglobin layer h, and the following equation (1) is obtained.

By taking the reciprocal of both sides of equation (1), the following equation (2) is obtained.

When the left side (apparent absorbance) of _{the equation (2) is expressed as A λ} , the equation (2) can be transformed as shown in the following equation (3).

C _m is the amount of melanin, _Ch is the amount of hemoglobin, M _λ and H _λ are the coefficients corresponding to the respective absorbances at the wavelength λ, and D is the apparent absorbance of the dermis, which is almost constant regardless of the wavelength λ, so it is a constant term. Can be regarded as. If the apparent absorbances in the two narrow wavelength bands λ1 and λ2 are A1 and A2, the following equation (4) can be obtained.

In equation (4), if λ1 and λ2 are selected so that M1-M2 is sufficiently small (ideally zero) and H1-H2 is sufficiently large, A1-A2 has a highly sensitive hemoglobin amount. the index, which is proportional to C _h. Similarly, if λ1 and λ2 are selected so that H1-H2 is sufficiently small and M1-M2 is sufficiently large, A1-A2 becomes an optimum index proportional to the _{amount of melanin C m.} Index MI of the resulting melanin amount C _m and hemoglobin C _h, EI is defined based on this concept, rather than representing a color, ideally linearly with amount of dye skin targeting It is a one-dimensional numerical value that is considered to correlate.

Further, by using a reflection spectrophotometer, since it can irradiate select light of good wavelength convenient, various formulas for obtaining the index EI index MI and Hemoglobin C _h melanin amount C _m has been proposed .. The models sold as an index meter, suitable for calculating the index EI index MI and Hemoglobin C _h melanin amount C _m, the LED emitting light of a specific narrow wavelength band is provided.

For example, when obtained by calculating the Ellis Ma index EI is the index of hemoglobin C _h is so as to reduce the effect of melanin, when irradiating the skin with light having a wavelength in the vicinity of a wavelength and 660nm of 540~570nm It is measured when the skin is irradiated with light of 5 wavelengths of 560 nm, 543 nm, 576 nm, 510 nm, and 610 nm, or a formula for subtracting the absorbance (A1-A2) using the apparent absorbance measured in. It has been proposed to calculate the erythma index EI by the formula (5) below, which is subtracted using each apparent absorbance.

In addition, when calculating and obtaining the melanin index MI, which is an index of the amount of melanin C _m , the wavelength of a long wavelength that is not easily affected by hemoglobin is, for example, 620 to 650 nm so as to reduce the influence of hemoglobin. The formula for subtracting the absorbance (A1-A2) using the apparent absorbance measured when the skin is irradiated with light having a wavelength of 670 to 700 nm (see, for example, Non-Patent Document 2), 620- The average value of the apparent absorbance measured when the skin is irradiated with light having a wavelength of 650 nm and the average value of the apparent absorbance measured when the skin is irradiated with light having a wavelength of 670 to 700 nm. It has been proposed to calculate the melanin index MI by a formula for subtracting the average value of absorbance (A1ave-A2ave) (see, for example, Non-Patent Document 3).

However, according to the conventional method of quantifying the pigment amount of melanin and the pigment amount of hemoglobin by the melanin index MI and the erythma index EI and evaluating the skin condition, the hemoglobin is used especially when calculating the melanin index MI. Hemoglobin is not so high in the long wavelength region, although the melanin index MI is calculated using the apparent absorptivity measured by irradiating long wavelength light so that the effect can be eliminated. The absorbance of deoxyhemoglobin is higher than that of oxyhemoglobin, and in actual blood, the spectrum shows a mixture of these, so the spectrum changes depending on the difference in oxygen saturation of blood. When the absorbance coefficient spectrum changes depending on the oxygen saturation of blood, the effect of deoxyhemoglobin with high absorbance cannot be sufficiently eliminated, and it becomes difficult to accurately calculate the melanin index MI. Therefore, such oxygen It is desired to develop a method for more accurately evaluating the condition of the skin by making it possible to calculate the melanin index MI more accurately without being affected by the difference in saturation.

The present invention evaluates the skin condition more appropriately by making it possible to calculate the melanin index MI and the erythma index EI more accurately without being affected by the difference in oxygen saturation of hemoglobin. The present invention relates to a skin condition evaluation method, a skin condition analyzer, and a skin condition analysis program.

The present invention is a method for evaluating a skin condition using a melanin index that reflects the amount of melanin contained in the skin. The melanin index is used as an extinction coefficient on an extinction coefficient spectrum of oxyhemoglobin and deoxy. The first-order absorption is defined as the first-equal absorption coefficient ratio wavelength and the second-equal absorption coefficient ratio wavelength, with the two wavelengths at which the hemoglobin interspecific absorption coefficient ratios, which are the ratio to the absorption coefficient on the extinction coefficient spectrum of hemoglobin, are equal. The apparent first absorbance measured when the skin is irradiated with light containing the coefficient ratio wavelength and the apparent second absorbance measured when the skin is irradiated with light containing the second extinction coefficient specific wavelength. Provide a method for evaluating the skin condition obtained from the above.

Further, the present invention is a skin condition analysis device including a skin condition analysis unit that evaluates the skin condition using a melanin index that reflects the amount of melanin contained in the skin, and the skin condition analysis unit is a wavelength selection unit. And a melanin index calculation unit, and the wavelength selection unit is a ratio of the absorbance coefficient on the absorption coefficient spectrum of oxyhemoglobin to the absorbance coefficient on the absorption coefficient spectrum of deoxyhemoglobin. Two wavelengths having the same ratio are selected as the first equal extinction coefficient specific wavelength and the second equal extinction coefficient specific wavelength, and the melanin index calculation unit irradiates the skin with light containing the first equal extinction coefficient specific wavelength. Skin condition analysis to obtain the melanin index from the apparent first absorbance measured when the wavelength is applied and the apparent second absorbance measured when the skin is irradiated with light containing the second equal extinction coefficient specific wavelength. Provide the device.

Further, the present invention is a skin condition analysis program incorporated and used in the skin condition analysis device, wherein the skin condition analysis unit is formed in the skin condition analysis device and the wavelength of the skin condition analysis unit is formed. In the selection section, two wavelengths at which the extinction coefficient ratio between hemoglobin species is equal, which is the ratio of the absorbance coefficient on the extinction coefficient spectrum of oxyhemoglobin and the absorbance coefficient on the extinction coefficient spectrum of deoxyhemoglobin, are set to the first equal absorption. The melanin index calculation unit is selected as the coefficient ratio wavelength and the second extinction coefficient ratio wavelength, and the apparent first absorbance measured when the skin is irradiated with light containing the first extinction coefficient ratio wavelength. Provided is a skin condition analysis program for obtaining a melanin index from the apparent second absorbance measured when the skin is irradiated with light containing the second equal extinction coefficient specific wavelength.

Furthermore, the present invention is a method for evaluating a skin condition using an erythma index that reflects the amount of hemoglobin contained in the skin, and the erythma index is used on the extinction coefficient spectrum of oxyhemoglobin. The two wavelengths at which the extinction coefficient ratio between species of hemoglobin, which is the ratio of the extinction coefficient of deoxyhemoglobin to the extinction coefficient on the extinction coefficient spectrum of deoxyhemoglobin, are equal, are defined as the first equal extinction coefficient specific wavelength and the second equal extinction coefficient specific wavelength. , The apparent first absorbance measured when the skin is irradiated with light containing the first equal extinction coefficient specific wavelength, and the apparent first absorbance measured when the skin is irradiated with light containing the second equal extinction coefficient specific wavelength. A method for evaluating a skin condition obtained from the above second absorbance is provided.

According to the skin condition evaluation method, the skin condition analyzer, or the skin condition analysis program of the present invention, the melanin index and the erythma index can be more accurately performed without being affected by the difference in oxygen saturation of hemoglobin. By making it possible to calculate, the condition of the skin can be evaluated more appropriately.

It is a chart of the absorption coefficient spectrum showing the relationship between the extinction coefficient and the wavelength of melanin, oxyhemoglobin and deoxyhemoglobin which are constituent pigments of skin color. It is explanatory drawing of the situation which the irradiated light is diffusely reflected in the multi-layer model of the skin which omitted the horny layer. It is explanatory drawing of the skin condition evaluation system including the hyperspectral imaging apparatus for obtaining the 2D image of the skin. 6 is a chart showing the relationship between the wavelength and the hemoglobin interspecific absorption coefficient ratio, which describes the iso-absorption coefficient ratio wavelength selected in Examples 1 to 3. Equal absorption selected in Examples 1 to 3 in a state in which melanin deposition was obtained by UV irradiation, a state in which methyl nicotinate was applied to obtain a blood flow promoting effect, and a state in which blood stasis was caused by tape hemostasis. It is explanatory drawing which shows each melanin image by a coefficient ratio wavelength. Explanatory drawing which shows the melanin image of Comparative Example 1 in the state which obtained melanin deposition by UV irradiation, the state which obtained the blood flow promotion effect by applying methyl nicotinate, and the state which was congested by tape hemostasis. Is. It is explanatory drawing which shows the melanin image by the iso-absorption coefficient ratio wavelength selected in Example 2 by changing the inter-wavelength absorption coefficient ratio α.

The skin condition evaluation method according to a preferred embodiment of the present invention includes information for appropriately evaluating a human skin condition, for example, the skin condition of an arm, palm, or face, more specifically. It was adopted as a method of presenting image information to an evaluator (a method of presenting information for evaluating skin condition). By using the skin condition evaluation method of the present embodiment, for example, the state of pigmentation derived from the amount of melanin, which is the main constituent pigment of skin color, can be appropriately grasped. That is, the skin condition evaluation method of the present embodiment is not affected by deoxyhemoglobin, for example, when calculating the melanin index MI for quantifying the _{amount of melanin C m} contained in the melanin layer m (see FIG. 2) of the skin. By making it possible to calculate accurately in this way, it has a function to make it possible to evaluate the condition of the skin more appropriately.

The skin condition evaluation method of the present embodiment is preferably an evaluation method for evaluating the skin condition using a melanin index MI that reflects the amount of melanin contained in the skin, and the melanin index MI is used as the oxyhemoglobin. Two points (equal extinction coefficient ratio points) 11 and 12 where the interspecific extinction coefficient ratios of hemoglobin, which are the ratios of the extinction coefficient on the extinction coefficient spectrum and the extinction coefficient of deoxyhemoglobin on the spectrum, are equal (see FIG. 1). The apparent first absorbance A measured when the skin is irradiated with light containing the first extinction coefficient ratio wavelength λ11, where the first extinction coefficient ratio wavelength λ11 and the second extinction coefficient ratio wavelength λ12 are used. and _{[lambda] 11,} obtained from the second absorbance a _{[lambda] 12} Metropolitan light of the apparent measured upon irradiating the skin, including the second, etc. extinction coefficient ratio wavelength [lambda] 12.

That is, in the present embodiment, the melanin index MI is the extinction coefficient and deoxyhemoglobin on the extinction coefficient spectrum of oxyhemoglobin, for example, in the extinction coefficient spectrum of FIG. 1 showing the relationship between the extinction coefficient and the wavelength of oxyhemoglobin and deoxyhemoglobin. The appearance measured when the skin is irradiated with light containing light with a wavelength of 525 nm at the first extinction coefficient ratio point 11, where the extinction coefficient ratio between species of hemoglobin, which is the ratio to the extinction coefficient on the extinction coefficient spectrum of _{The apparent second absorbance A λ12} (A ₅₆₈₎ measured when the skin is irradiated with light containing the above first absorbance A _λ11 (A ₅₂₅ ) and light with a wavelength of 568 nm at the second extinction coefficient ratio point 12. ) Is calculated by the following formula (6).

When the wavelength of the first equal absorption coefficient ratio point 11 and the wavelength of the second equal absorption coefficient ratio point 12 are selected from the absorption coefficient spectrum of oxyhemoglobin and the absorption coefficient spectrum of deoxyhemoglobin, these equal absorption coefficients are selected. Even if the wavelength of the specific point (525 nm, 568 nm) deviates from the accurate wavelength by about ± 10 nm, it is considered that there is no practical problem.

Further, in the present embodiment, in the formula (6), the apparent first extinction coefficient A measured when the skin is irradiated with light containing the first extinction coefficient ratio wavelength λ11 which is preferably the shorter wavelength. _{To λ11} (A ₅₂₅ ), the ratio of the extinction coefficient of oxyhemoglobin to the extinction coefficient at the first extinction coefficient ratio wavelength λ11 to the extinction coefficient at the second extinction coefficient ratio wavelength λ12, or the extinction of deoxyhemoglobin at the first extinction coefficient ratio wavelength λ11. Second-equal extinction coefficient ratio to coefficient Multiply the inter-wavelength absorption coefficient ratio α, which is the ratio of the extinction coefficient at wavelength λ11, and then irradiate the skin with light containing the second equivalent extinction coefficient ratio wavelength λ12, which is the longer wavelength. _{By subtracting the apparent second extinction coefficient} A λ12 (A ₅₆₈ ) measured at the time, the melanin index is obtained and the condition of the skin is evaluated.

Further, in the skin condition evaluation method of the present embodiment, the skin condition is evaluated using the melanin index MI and the erythma index EI that reflects the amount of hemoglobin contained in the skin. _{That is, 2 of the melanin index MI for quantifying the amount of melanin C m} contained in the melanin layer m of the skin and the erythma index EI for quantifying the _{amount of hemoglobin C b} contained in the hemoglobin layer h of the skin (see FIG. 2). The skin condition is evaluated using one index as an index. The erythma index EI is calculated from the apparent absorbance.

Lambert-Beer's law makes it possible to calculate the reflectance by converting it to the apparent absorbance (the logarithm of the reciprocal of the reflectance), as described above. In the present embodiment, assuming a multi-layer model of the skin shown in FIG. 2 in which the stratum corneum is omitted, the above equation (1) is modified to further obtain the above equations (2) and (3). Eq. (4) could be obtained. In equation (4), if the wavelengths λ1 and λ2 are selected so that M1-M2 is sufficiently small (ideally zero) and H1-H2 is sufficiently large, A1-A2 is a highly sensitive hemoglobin. It is considered _{that the index (erythma index EI) proportional to the amount C b} makes it possible to accurately quantify the amount of dye of hemoglobin. Similarly, if the wavelengths λ1 and λ2 are selected so that H1-H2 is sufficiently small and M1-M2 is sufficiently large, A1-A2 becomes the optimum index (melanin index MI) proportional to the _{amount of melanin C m.} , It is considered that the amount of melanin pigment can be quantified with high accuracy. The inventor of the present application has completed the invention of the present application based on these ideas.

In the present embodiment, the extinction coefficient on the extinction coefficient spectrum of oxyhemoglobin and the deoxyhemoglobin shown in FIG. As light containing wavelengths λ11 and λ12 at equal extinction coefficient ratio points 11 and 12, which are ratios to the extinction coefficient on the extinction coefficient spectrum, for example, λ11 = wavelength 525 nm, λ12 = wavelength 568 nm. light including light is measured upon irradiating the skin, apparent absorbance _a λ11 (a 525), and calculated from _a λ12 (a _568), to obtain the melanin index MI.

Here, the absorption coefficient spectrum of oxyhemoglobin showing the relationship between the absorption coefficient of oxyhemoglobin and the wavelength and the absorption coefficient spectrum of deoxyhemoglobin showing the relationship between the absorption coefficient of deoxyhemoglobin and the wavelength are peculiar to oxyhemoglobin and deoxyhemoglobin. It is a known spectrum that has already been verified as the physical properties of. As shown in FIG. 1, the absorption coefficient spectrum of oxyhemoglobin has a wavy value of the absorption coefficient, and in the long wavelength region exceeding 600 nm, the absorption coefficient becomes a value close to 0 as the wavelength increases. It gradually decreases. The absorption coefficient spectrum of deoxyhemoglobin also has a wavy value, and in the long wavelength region exceeding 600 nm, the absorption coefficient gradually decreases as the wavelength increases, but the absorption coefficient is higher than that of oxyhemoglobin. It remains high. For this reason, the conventional formula that made it possible to eliminate the effect of hemoglobin by calculating the melanin index MI using the apparent absorbance measured by irradiating light with a long wavelength excludes the effect of oxyhemoglobin. Even if it was possible, the effects of deoxyhemoglobin could not be sufficiently eliminated.

Further, since the extinction coefficient spectrum of oxyhemoglobin and the extinction coefficient spectrum of deoxyhemoglobin shown in FIG. 1 are different in the wavy shape of each spectrum, the extinction coefficient and deoxyhemoglobin on the extinction coefficient spectrum of oxyhemoglobin are different. The equi-extinction coefficient ratio points, which are the ratios to the extinction coefficient on the extinction coefficient spectrum of the above, and which have the same extinction coefficient ratio between hemoglobin species, appear at a plurality of places. In this embodiment, equation (4) the apparent absorbance A1 (A _{[lambda] 11) by,} A2 (A _{[lambda] 12)} calculating the time of obtaining the melanin index MI in the, etc extinction coefficient ratio hemoglobin species between extinction coefficient ratio is equal The wavelength of the point is used as the wavelength of light to irradiate the skin. By using the wavelengths λ11 and λ12 of the equivalence coefficient ratio points as the wavelengths for obtaining the melanin index MI calculated from the apparent absorbances A1 and A2, the influence of oxyhemoglobin and deoxyhemoglobin is suppressed, and the accuracy is high. It becomes possible to efficiently obtain the melanin index MI.

Further, in the present embodiment, the wavelength of the equal absorption coefficient ratio point used when obtaining the melanin index MI by calculating from the apparent absorbances A1 and A2 by the formula (4) is, for example, the first equal absorption coefficient ratio point 11. Wavelengths λ11, λ12 at two equal absorption coefficient ratio points 11 and 12, the first equal absorption coefficient ratio wavelength λ11 at 525 nm and the second equal absorption coefficient ratio wavelength λ12 at the second equal absorption coefficient ratio point 12 at 568 nm. Is used. These iso-absorption coefficient ratio points 11 and 12 are selected so that the difference between the wavelengths λ11 and λ12 is within a preferable range of 50 nm. By keeping the difference between the first equal absorption coefficient ratio wavelength λ11 of the first equal absorption coefficient ratio point 11 and the second equal absorption coefficient specific wavelength λ12 of the second equal absorption coefficient ratio point 12 within the range of 10 to 200 nm, the first Since the first equal absorption coefficient specific wavelength λ11 at the first equal absorption coefficient ratio point 11 and the second equal absorption coefficient specific wavelength λ12 at the second equal absorption coefficient ratio point 12 are relatively close values, the reflection of the dermis by the wavelength. It is possible to obtain the melanin index MI without or by reducing the influence of the difference in characteristics and the difference in the penetration depth of light into the skin depending on the wavelength.

Here, as the wavelength of the equal absorption coefficient ratio points when the melanin index MI (A1-A2) is obtained by calculating from the apparent absorbances A1 and A2 by the formula (4), the equal absorption coefficient ratio points 11 at two locations, It is not always necessary to use the wavelengths λ11 and λ12 in 12, for example, the wavelength λ11 of the first equal absorption coefficient ratio point 11, the wavelength λ12 of the second equal absorption coefficient ratio point 12, and the wavelength λ13 of the third equal absorption coefficient ratio point 13. It is also possible to use the wavelengths λ11, λ12, and λ13 at the three equal absorption coefficient ratio points 11, 12, and 13. For example, the average value of the wavelength λ11 of the first extinction coefficient ratio point 11 and the wavelength λ12 of the second extinction coefficient ratio point 12 is defined as the wavelength of the first extinction coefficient ratio point, and the wavelength of the third extinction coefficient ratio point 13 is used. The melanin index MI can also be calculated by Eq. (4) from these differences, with λ13 as the wavelength of the second extinction coefficient ratio point.

Further, in the present embodiment, as described above, the melanin index MI is apparently measured when the skin is irradiated with light containing the first extinction coefficient ratio wavelength λ11, which is preferably the shorter wavelength. First extinction coefficient ratio of oxyhemoglobin to first extinction A _λ11 (A ₅₂₅ ) Second extinction coefficient ratio of oxyhemoglobin to extinction coefficient at wavelength λ11 Second-equal extinction coefficient ratio to extinction coefficient at wavelength λ11 After multiplying the inter-wavelength absorption coefficient ratio α, which is the ratio of the extinction coefficient at wavelength λ11, light containing the second-equal extinction coefficient ratio wavelength λ12, which is the longer wavelength, is obtained. _{By subtracting the apparent second extinction A λ12} (A ₅₆₈ ) measured when the skin is irradiated, it can be obtained by the above equation (6).

That is, in the present embodiment, as shown in the column of Example 1 in Table 1 in Examples described later, the shorter wavelength, the first extinction coefficient ratio wavelength λ11, is set to 525 nm, and the longer wavelength is used. Since the second equal extinction coefficient specific wavelength λ12, which is the wavelength, was set to a wavelength of 568 nm, the extinction coefficient of oxyhemoglobin at the first equal extinction coefficient specific wavelength λ11 was 30883 [cm ^-1 / (moles / liter)]. Second extinction coefficient The extinction coefficient at the specific wavelength λ12 is 40172 [cm ^-1 / (moles / liter)]. Therefore, the ratio of the extinction coefficient of oxyhemoglobin at the first extinction coefficient ratio wavelength λ11 to the extinction coefficient at the second extinction coefficient ratio wavelength λ12 is 40172/30883 = 1.30. The extinction coefficient of deoxyhemoglobin at the first extinction coefficient ratio wavelength λ11 is 35171 [cm ^-1 / (moles / liter)], and the extinction coefficient at the second extinction coefficient ratio wavelength λ12 is 46948 [cm ^-1]. / (Moles / liter)]. Therefore, the ratio of the extinction coefficient of deoxyhemoglobin at the first extinction coefficient ratio wavelength λ11 to the extinction coefficient at the second extinction coefficient ratio wavelength λ12 is 46948/35171 = 1.33.

In the present embodiment, as described above, when selecting the wavelength of the first equal extinction coefficient ratio point 11 and the wavelength of the second equal extinction coefficient ratio point 12, the wavelengths of these equal extinction coefficient ratio points (525 nm, 568 nm). ) Is considered to have no problem in practical use even if the value deviates from the accurate wavelength by about ± 10 nm. Therefore, the ratio of the extinction coefficient at the second extinction coefficient ratio wavelength λ12 to the extinction coefficient at the first extinction coefficient ratio wavelength λ11 of oxyhemoglobin is the ratio of the extinction coefficient at the first extinction coefficient ratio wavelength λ11 of deoxyhemoglobin. , The ratio of the extinction coefficient at the second extinction coefficient ratio wavelength λ12 to the extinction coefficient at the first extinction coefficient ratio wavelength λ11 of oxyhemoglobin, or the ratio of the extinction coefficient at the first extinction coefficient ratio wavelength λ11 of deoxyhemoglobin. The ratio of the extinction coefficient at the second equal extinction coefficient ratio wavelength λ12 to the extinction coefficient in It has become.

The inter-wavelength absorption coefficient _{is based on the apparent first absorbance A λ11} (A ₅₂₅ ) measured when the skin is irradiated with light containing the first equal extinction coefficient specific wavelength λ11, which is the shorter wavelength of the melanin index MI. Multiply by the ratio α and then subtract the _{apparent second absorbance A λ12} (A ₅₆₈ ) measured when the skin is irradiated with light containing the longer wavelength, the second extinction coefficient specific wavelength λ12. by obtaining in, it has become possible to effectively eliminate the influence of oxyhemoglobin and deoxyhemoglobin both be melanin index MI of the melanin index proportional only to the amount of melanin C _m, obtain higher accuracy It will be possible.

In the present embodiment, the condition of the skin is further evaluated using the melanin index MI and the erythma index EI that reflects the amount of hemoglobin contained in the skin. The erythma index EI is calculated from the apparent absorbance. In the present embodiment, Ellis Ma index EI, as described above, hemoglobin C _h was devised as an expression for obtaining the Ellis Ma index EI is the index of, among various known formulas, more accurately It can be calculated using the above equation (5), which is considered to be able to calculate the erythma index EI. That is, the erythma index is preferably calculated from the apparent absorbance of light having at least two wavelengths of 500 nm or more and 700 nm or less so as to reduce the influence of melanin, and is preferably 560 nm, 543 nm, 576 nm, 510 nm, and 610 nm. It is more preferable to calculate and obtain the erythrma index EI by the above formula (5) in which subtraction is performed using each apparent absorbance measured when the skin is irradiated with the five wavelengths of light. In the present embodiment, a melanin image and a hemoglobin image are created based on the calculated erythma index EI and the above-mentioned melanin index MI, and the created melanin image and hemoglobin image are presented or statistically processed. By doing so, it is possible to evaluate the condition of the skin.

In this embodiment, the erythma index EI, which reflects the amount of hemoglobin contained in the skin, is the ratio of the extinction coefficient on the extinction coefficient spectrum of oxyhemoglobin to the extinction coefficient on the extinction coefficient spectrum of deoxyhemoglobin. Let the wavelengths of the two points 11 and 12 (see FIG. 1) having the same extinction coefficient ratio be the first equal extinction coefficient specific wavelength λ11 and the second equal extinction coefficient specific wavelength λ12, and light containing the first equal extinction coefficient specific wavelength λ11. a first absorbance a _{[lambda] 11} apparent that measured upon irradiating the skin, the second absorbance a _{[lambda] 12} Metropolitan light of the apparent measured upon irradiating the skin, including the second, etc. extinction coefficient ratio wavelength [lambda] 12 You can also ask. This makes it possible to effectively eliminate the influence of the difference in the absorption coefficient spectra of oxyhemoglobin and deoxyhemoglobin and obtain the erythma index EI more accurately. For example, the state of blood flow in the hemoglobin layer. It becomes possible to evaluate the skin condition such as, etc. more accurately.

Further, in the present embodiment, in order to evaluate the condition of the skin, for example, the skin of a human face part is photographed by using a hyperspectral imaging device, and each of the two-dimensional images of the skin of the photographed face part is taken. Calculate the melanin index and erythma index for the pixels. The evaluation of the skin condition using the melanin index MI and the erythma index EI is not limited to the method of evaluating via the image captured by the hyperspectral imaging apparatus described later, and is not limited to, for example, general spectroscopy. A colorimeter (for example, trade name: CM-2600d, manufactured by Konica Minolta) can also be used in a method or system for evaluating the condition of the skin in a specific area of the skin.

Here, the skin condition evaluation system 1 shown in FIG. 3 can be used as a system for photographing the skin of a human face using a hyperspectral imaging device. The skin condition evaluation system 1 shown in FIG. 3 includes a lighting device 2 that irradiates a subject, for example, a person's arm, palm, or face with light of a predetermined wavelength, and a face portion that is illuminated by the lighting device 2. For each pixel of the hyperspectral imaging device 3 and the image captured by the hyperspectral imaging device 3, the amount of hemoglobin and the amount of melanin are quantified using the above formulas (5) and (6) to determine the amount of hemoglobin. It is configured to include a skin condition evaluation device 4 capable of creating an image and a melanin image and evaluating the skin condition from the quantified amount of hemoglobin and melanin of each pixel.

The lighting device 2 has an opening 20a that allows the subject, for example, a person's arm, palm, or face to face the inside from the A direction, and the lens portion of the hyperspectral imaging device 3 from the B direction. A lighting box 20 having a lens insertion port 20b capable of facing the light source, and a light source that irradiates light of a predetermined wavelength toward, for example, a person's arm, palm, or face facing the inside of the lighting box 20. It is configured to include (not shown).

The lighting box 20 is formed in a hemispherical shape, and the inner surface thereof is treated with a white pear ground. The pear-ground processing is a fine and uniform roughness processing on the surface. By applying the pear ground processing to the inner surface, it becomes possible to make the inside of the lighting box 20 matte. Further, it becomes possible to improve the diffusivity of the light emitted from the light source, and it becomes possible to irradiate the subject, for example, the face with uniform light. The light source is arranged inside the lighting box 20, and a white LED is preferably used.

The hyperspectral imaging device 3 has a number of bands (wavelength resolution) of several tens to several hundreds of bands, and is compared with a three-band RGB (human eye) or a multispectral camera having several to several tens of bands. Therefore, it is known as a camera capable of viewing the spectral shape of physical properties more continuously. Further, the hyperspectral imaging device 3 visualizes changes that cannot be identified by color (RGB), visualizes invisible phenomena, and captures changes in the spectrum as an image, so that it is equivalent to or equal to the human eye. It has a function that can recognize the above color changes. As such a hyperspectral imaging device 3, for example, the product name "Hyperspectral Camera NH-7" (manufactured by Eva Japan, resolution: 1,311,000 pixels, wavelength range: 400 to 1000 nm, wavelength resolution: 5 nm) is used. Can be done.

In the present embodiment, the hyperspectral imaging device 3 is fixed in a state where the lens is inserted into the lens insertion port 20b formed in the illumination box 20 arranged on the straight line in the B direction at the time of imaging.

The skin condition evaluation device 4 includes a CPU that calculates the melanin index MI and the erythma index EI, a volatile RAM that stores a program for calculating the melanin index MI and the erythma index EI, and the calculated melanin index. A non-volatile ROM that can temporarily store MI, erythma index EI, etc., a monitor that presents the calculated melanin index MI, erythma index EI, etc. as an image, and a mouse and keyboard for operating these. It is configured to include. As the skin condition evaluation device 4, for example, a general-purpose personal computer can be used.

In the present embodiment, for example, a skin condition evaluation device 4 using a general-purpose personal computer incorporates a skin condition analysis program that evaluates the skin condition using a melanin index that reflects the amount of melanin contained in the skin. The skin condition analysis program forms a skin condition analysis unit on the skin condition evaluation device 4. As a result, the skin condition evaluation device 4 includes a skin condition analysis unit. The skin condition analysis unit includes a wavelength selection unit and a melanin index calculation unit, and the wavelength selection unit is a ratio of the extinction coefficient on the extinction coefficient spectrum of oxyhemoglobin to the extinction coefficient on the extinction coefficient spectrum of deoxyhemoglobin. The wavelengths of the two points 11 and 12 (see FIG. 1) at which the extinction coefficient ratios between the hemoglobin species are equal are selected as the first equal extinction coefficient ratio wavelength λ11 and the second equal extinction coefficient ratio wavelength λ12. .. The melanin index calculation unit irradiates the skin with the apparent first absorbance measured when the skin is irradiated with light containing the first extinction coefficient specific wavelength λ11 and the light containing the second extinction coefficient specific wavelength λ12. The melanin index MI is obtained from the apparent second absorbance measured at that time.

In addition, the skin condition analysis unit includes an inter-wavelength absorption coefficient ratio calculation unit. The inter-wavelength absorption coefficient ratio calculation unit determines the ratio of the extinction coefficient at the second extinction coefficient ratio wavelength λ12 to the extinction coefficient at the first extinction coefficient ratio wavelength λ11 of oxyhemoglobin, or the first extinction coefficient ratio wavelength λ11 of deoxyhemoglobin. The second-equal extinction coefficient ratio to the extinction coefficient in λ12 is the ratio of the extinction coefficient at the wavelength λ12. After multiplying the apparent first extinction measured when the containing light is applied to the skin by the inter-wavelength absorption coefficient ratio α, the skin is subjected to light containing the second extinction coefficient ratio wavelength λ12, which is the longer wavelength. The melanin index MI is obtained by the above equation (6) by subtracting the apparent second extinction measured when the sardine is irradiated.

That is, in the skin condition analysis program, the skin condition analysis unit is formed in the skin condition analysis device 4, and the wavelength selection unit of the skin condition analysis unit contains the extinction coefficient on the extinction coefficient spectrum of oxyhemoglobin and the absorbance of deoxyhemoglobin. The wavelengths of the two points 11 and 12 (see FIG. 1) at which the hemoglobin interspecific absorbance ratios, which are the ratio to the absorbance coefficient on the coefficient spectrum, are the same, are the first equal extinction coefficient specific wavelength λ11 and the second equal extinction coefficient specific wavelength. The melanin index calculation unit is selected as λ12, and the apparent first absorbance measured when the skin is irradiated with light containing the first equal extinction coefficient specific wavelength λ11 and the second equal extinction coefficient specific wavelength λ12 are selected. The melanin index is obtained from the apparent second absorbance measured when the skin is irradiated with the contained light.

In addition, the skin condition analysis program forms an inter-wavelength absorption coefficient ratio calculation unit in the skin condition analysis unit, and the inter-wavelength absorption coefficient ratio calculation unit contains the absorption coefficient of oxyhemoglobin at the first equal extinction coefficient ratio wavelength λ11. Second equal extinction coefficient ratio relative to The ratio is calculated, and the melanin index calculation unit absorbs between wavelengths to the apparent first extinction measured when the skin is irradiated with light containing the shorter wavelength, the first extinction coefficient ratio wavelength λ11. The melanin index is multiplied by the coefficient ratio α and then subtracted from the apparent second extinction measured when the skin is irradiated with light containing the longer wavelength, the second extinction coefficient ratio wavelength λ12. Is being asked.

In the present embodiment, for example, various known image analysis programs are incorporated in the skin condition evaluation device 4 using a general-purpose personal computer, and in the incorporated image analysis program, the above equation (5) is used. The erythma index EI and the melanin index MI are calculated for each pixel of the image of the human face, which is the subject, taken by the hyperspectral imaging device 3 by incorporating the equation (6). Further, based on the calculated erythma index EI and melanin index MI, the amount of hemoglobin and the amount of melanin in the skin are quantified, and a melanin image and a hemoglobin image are created. By presenting the created melanin image and hemoglobin image, the evaluator can determine the state of pigmentation that affects the whitening effect such as spots, freckles, and dullness derived from the amount of melanin pigment, and the amount of hemoglobin pigment. It has become possible to evaluate the condition of the skin by grasping the condition such as hemoglobin and inflammation caused by melanin.

That is, in the present embodiment, the skin condition evaluation device 4 uses a skin image composed of a plurality of pixels, and obtains a melanin index MI and an erythma index EI for each pixel or an arbitrary region of the skin image. , The condition of the skin can be evaluated. In addition, a melanin image and a hemoglobin image can be created based on the calculated melanin index MI and erythma index EI of each pixel or region, and the skin condition can be evaluated from the created melanin image and hemoglobin image. .. Further, in the present embodiment, the skin condition can be evaluated from the calculated uniformity (dispersion) of the melanin index MI and / or the erythma index EI of each pixel.

Then, according to the skin condition evaluation method of the present embodiment having the above-described configuration, the melanin index MI can be calculated more accurately without being affected by the difference in oxygen saturation of hemoglobin, whereby the skin condition can be calculated. Can be evaluated more appropriately.

That is, according to the present embodiment, the melanin index MI has an equal extinction coefficient ratio between species of hemoglobin, which is the ratio of the extinction coefficient on the extinction coefficient spectrum of oxyhemoglobin to the extinction coefficient on the extinction coefficient spectrum of deoxyhemoglobin. The skin was irradiated with light containing the first equal extinction coefficient specific wavelength λ11, with the wavelengths of the two points (equal extinction coefficient ratio points) 11 and 12 as the first equal extinction coefficient specific wavelength λ11 and the second equal extinction coefficient specific wavelength λ12. a first absorbance a _{[lambda] 11} apparent that measured in obtained from the second absorbance a _{[lambda] 12} Metropolitan light of the apparent measured upon irradiating the skin, including the second, etc. extinction coefficient ratio wavelength [lambda] 12.

As a result, according to the present embodiment, in the above equation (4) obtained based on the Lambert-Beer law, H1-H2 is sufficiently small (ideally zero) and M1-M2 is sufficiently small. Since it is possible to make it a large value, regardless of the difference in oxygen saturation of hemoglobin, the amount of melanin C _{m contained in the melanin layer m of the skin is not particularly affected by deoxyhemoglobin.} The reflected melanin index MI can be calculated with high accuracy, which makes it possible to evaluate the skin condition more appropriately.

The present invention is not limited to the above embodiment, and various modifications can be made. For example, instead of shooting with a hyperspectral imaging device, a wavelength on the light source side may be selected by, for example, a filter or the like and applied to a subject, and the reflection intensity may be shot with a monochrome camera. Further, for each pixel of the two-dimensional image of the skin taken by using the above-mentioned hyperspectral imaging device, the melanin index and the erythma index are calculated to evaluate the skin condition, or from the created melanin image and hemoglobin image. It is not always necessary to evaluate the skin condition, and various other devices and systems can be used to calculate the melanin index to evaluate the skin condition. For example, a reflectance measuring unit having a function of irradiating the skin with light containing two or more specific wavelengths and measuring the reflected wave, and a reflectance data obtained by the reflectance measuring unit in a specific region. A simple control calculation unit that has a function to obtain a plurality of reflection coefficients of the skin as an average value, calculate and display the melanin index and the erythma index from the reflection coefficients of the plurality of wavelengths using a predetermined formula. The present invention can also be carried out by using a quantifying device having various configurations.

Hereinafter, the method for evaluating the skin condition of the present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited by the description of the following Examples and Comparative Examples.

[Examples 1 to 3]
In the chart showing the relationship between the wavelength and the extinction coefficient ratio between hemoglobin species shown in FIG. 4, the extinction coefficient ratio between hemoglobin species is approximately 1.0 (the extinction coefficient of oxyhemoglobin and the extinction coefficient of deoxyhemoglobin are approximately equal). The equal extinction coefficient ratio points of the wavelengths of 530 nm and 570 nm are selected as the first equal extinction coefficient ratio points (first equal ratio points) and the second equal extinction coefficient ratio points (second equal ratio points) of Example 1. Then, the equi-extinction coefficient ratio points of the wavelength of 525 nm and the wavelength of 568 nm, which have a hemoglobin interspecific extinction coefficient ratio of approximately 0.86, are set as the first extinction coefficient ratio point (first equivalence point) and the first equivalence point of Example 2. The equi-extinction coefficient ratio points of the wavelengths of 515 nm and 565 nm, which are selected as the second-equal extinction coefficient ratio points (second-equal ratio points) and have a hemoglobin interspecific extinction coefficient ratio of approximately 0.72, are set as the second-equal extinction coefficient ratio points of Example 3. It was selected as the first-equal extinction coefficient ratio point (first-equal ratio point) and the second-equal extinction coefficient ratio point (second-equal ratio point).

Equivalent absorption coefficient ratio wavelength, absorption of oxyhemoglobin with respect to the first equal absorption coefficient ratio point (first equal ratio point) and the second equal absorption coefficient ratio point (second equal ratio point) of selected Examples 1 to 3. Coefficient, deoxyhemoglobin absorption coefficient, hemoglobin interspecific absorption coefficient ratio, oxyhemoglobin inter-wavelength absorption coefficient ratio, deoxyhemoglobin inter-wavelength absorption coefficient ratio, and oxyhemoglobin inter-wavelength absorption coefficient ratio and deoxyhemoglobin inter-wavelength absorption coefficient ratio The average value with the ratio is shown in Table 1.

[Calculation of melanin index MI and creation of melanin image]
As human skin, the skin of the inner part of the subject's arm was irradiated with UV, and after 3 months, the skin of the inner part of the subject's arm was subjected to UV irradiation in a state where melanin deposition was obtained. The image was taken using a skin condition evaluation system having the same configuration as the skin condition evaluation system 1 used. As human skin, after applying methyl nicotinate to the skin of the inner part of the subject's arm to obtain a blood flow promoting effect, the skin of the inner part of the subject's arm to which methyl nicotinate is applied is applied in the above embodiment. The image was taken using a skin condition evaluation system having the same configuration as the skin condition evaluation system 1 used. As human skin, the skin of the finger pad, which is the part of the subject's hand beyond the first joint of the middle finger, is congested by tape-stopping between the first and second joints, and then the subject's hand. The skin was photographed using a skin condition evaluation system having the same configuration as the skin condition evaluation system 1 used in the above embodiment.

A melanin index MI was calculated for each pixel of these two-dimensional images taken, and a melanin image was created. The melanin index MI is calculated by using a spectroscopic reflection image of light containing the first extinction coefficient ratio wavelength of the first extinction coefficient ratio point and light containing the second extinction coefficient ratio wavelength of the second extinction coefficient ratio point. The apparent first absorbance and the apparent second absorbance were obtained for each pixel according to the above formula (6). The prepared melanin image is shown in FIG.

[Comparative Example 1]
For each pixel of each two-dimensional image similar to the above, the melanin index MI was calculated by the conventional formula to create a melanin image. That is, the melanin index MI is calculated by using the average value of the spectroscopic images of 620 to 640 nm and the average value of the spectroscopic images of 670 to 690 nm for each pixel of the photographed two-dimensional image of the subject's skin. The average value of the apparent absorbance (Aave620 to 640, Aave670 to 690) measured at the time of reflection was obtained, and the average value was obtained for each pixel according to the conventional formula (Aave620 to 640-Aave670 to 690). The prepared melanin image of Comparative Example 1 is shown in FIG.

According to the melanin images of Example 1, Example 2, and Example 3 shown in FIG. 5, the amount of pigment of deoxyhemoglobin such as congestion and veins that could not be excluded by the melanin image of Comparative Example 1 shown in FIG. It turns out that the part derived from is excluded from the image. As a result, according to the present invention, it is found that the melanin index MI can be calculated more accurately without being affected by the difference in oxygen saturation of hemoglobin.

[Study on deviation of absorption coefficient ratio α between wavelengths]
When calculating the melanin index MI according to Example 2 in which the first equal extinction coefficient ratio wavelength of the first equal ratio point is 525 nm and the second equal extinction coefficient ratio wavelength of the second equal ratio point is 568 nm, the inter-wavelength absorption coefficient The effect of the deviation of the ratio α was examined. That is, in Example 2, the inter-wavelength absorption coefficient ratio α obtained by calculation was 1.32, whereas the inter-wavelength absorption coefficient ratio α was 1.00, 1.20, 1.40. The melanin index MI was calculated by changing to 1.60 and 2.00, and in the same manner as described above, in the state where melanin was deposited by UV irradiation, methyl nicotinate was applied to obtain a blood flow promoting effect. A melanin image was created in a state of being congested by stopping bleeding with tape. The prepared melanin image is shown in FIG. 7 together with the melanin image according to Example 2.

According to the melanin image in which the influence of the deviation of the inter-wavelength absorption coefficient ratio α shown in FIG. 7 is examined, even if the inter-wavelength absorption coefficient ratio α is deviated due to a difference in devices, for example, if the deviation is about ± 10%. , It turns out that there is no problem in practical use. When the inter-wavelength absorption coefficient ratio α is 1.00, 1.60, and 2.00, the effect of hemoglobin increased by the application of methyl nicotinate and the effect of dehemoglobin increased by congestion are melanin. It turns out that it is detected as.

1 Skin condition evaluation system 2 Lighting device 3 Hyperspectral imaging device 4 Skin condition evaluation device (personal computer)
11 First-equal extinction coefficient ratio point 12 Second-equal extinction coefficient ratio point 13 Third-equal extinction coefficient ratio point 20 Lighting box 20a Opening 20b Lens insertion port MI Melanin index EI Erisma index m Melanin layer h Hemoglobin layer d Dermal layer

Claims (13)

It is a calculation method of the melanin index that obtains the melanin index that reflects the amount of melanin contained in the skin in order to evaluate the condition of the skin.
The melanin index is the ratio of the extinction coefficient on the extinction coefficient spectrum of oxyhemoglobin to the extinction coefficient on the extinction coefficient spectrum of deoxyhemoglobin. The coefficient ratio wavelength and the second extinction coefficient ratio wavelength include the apparent first absorbance measured when the skin is irradiated with light including the first extinction coefficient ratio wavelength and the second extinction coefficient ratio wavelength. A method for calculating the melanin index, which is obtained from the apparent second absorbance measured when the skin is irradiated with light. The apparent first extinction measured when the skin is irradiated with light containing the first extinction coefficient specific wavelength, which is the shorter wavelength, is the first extinction coefficient of oxyhemoglobin with respect to the extinction coefficient at the first extinction coefficient specific wavelength. Multiply the ratio of the extinction coefficient at the second extinction coefficient ratio wavelength or the inter-wavelength absorption coefficient ratio, which is the ratio of the extinction coefficient at the second extinction coefficient ratio wavelength to the extinction coefficient at the first extinction coefficient ratio wavelength of deoxyhemoglobin. The melanin index is obtained by subtracting the apparent second extinction measured when the skin is irradiated with light containing the second extinction coefficient ratio wavelength, which is the longer wavelength . How to calculate the melanin index . The method for calculating a melanin index according to claim 1 or 2, wherein the difference between the first-equal absorption coefficient ratio wavelength and the second-equal absorption coefficient ratio wavelength is 10 to 200 nm. The method for calculating a melanin index according to any one of claims 1 to 3, wherein an image of skin composed of a plurality of pixels is used to obtain the melanin index for each pixel or any region of the image. To assess the skin condition, the method of calculating the melanin index of any one of claims 1 to 4, with determining the melanin index, obtaining the Ellis Ma index that reflects the amount of hemoglobin contained in the skin melanin It is a calculation method of index and erythma index.
The erythma index is a method for calculating the melanin index and the erythma index, which is calculated from the apparent absorbance. The method for calculating a melanin index and an erythma index according to claim 5 , wherein a melanin image and a hemoglobin image are created based on the calculated melanin index and the erythma index of each pixel. The method for calculating the melanin index and the erythma index according to claim 6, wherein the calculated uniformity of the melanin index and / or the erythma index of each pixel is obtained. A skin condition analysis device that includes a skin condition analysis unit that evaluates the condition of the skin using a melanin index that reflects the amount of melanin contained in the skin.
The skin condition analysis unit includes a wavelength selection unit and a melanin index calculation unit.
The wavelength selection unit sets the wavelengths at two points where the interspecific absorption coefficient ratios of oxyhemoglobin are equal, which is the ratio of the absorption coefficient on the absorption coefficient spectrum of oxyhemoglobin and the absorption coefficient on the absorption coefficient spectrum of deoxyhemoglobin. Select as the absorption coefficient specific wavelength and the second equal absorption coefficient specific wavelength,
The melanin index calculation unit applies the apparent first absorbance measured when the skin is irradiated with light containing the first equal extinction coefficient specific wavelength and the light containing the second equal extinction coefficient specific wavelength to the skin. A skin condition analyzer that obtains the melanin index from the apparent second absorbance measured when irradiated. The skin condition analysis unit includes an inter-wavelength absorption coefficient ratio calculation unit, and the inter-wavelength absorption coefficient ratio calculation unit is the second-equal absorption coefficient with respect to the extinction coefficient of oxyhemoglobin at the first-equal extinction coefficient ratio wavelength. The ratio of the extinction coefficient at the specific wavelength or the ratio of the extinction coefficient at the second extinction coefficient ratio wavelength to the extinction coefficient at the first extinction coefficient ratio wavelength of deoxyhemoglobin is calculated, and the interwavering absorption coefficient ratio is calculated. The index calculation unit multiplies the apparent first extinction coefficient measured when the skin is irradiated with light containing the first extinction coefficient ratio wavelength, which is the shorter wavelength, by the inter-wavelength absorption coefficient ratio. 8. The melanin index is obtained by subtracting the apparent second extinction measured when the skin is irradiated with light containing the second extinction coefficient ratio wavelength, which is the longer wavelength. Skin condition analyzer. The skin condition analysis apparatus according to claim 8 or 9, wherein a skin image composed of a plurality of pixels is used, and the melanin index is obtained for each pixel or an arbitrary region of the image. A skin condition analysis program incorporated and used in the skin condition analysis apparatus according to any one of claims 8 to 10.
The skin condition analysis unit is formed in the skin condition analysis device, and the wavelength selection unit of the skin condition analysis unit includes the absorbance coefficient on the extinction coefficient spectrum of oxyhemoglobin and the extinction coefficient on the extinction coefficient spectrum of deoxyhemoglobin. Two wavelengths having the same hemoglobin interspecific extinction coefficient ratio, which is the ratio of The apparent first absorbance measured when the skin is irradiated with light containing the equal extinction coefficient specific wavelength, and the apparent first absorbance measured when the skin is irradiated with light containing the second equal extinction coefficient specific wavelength. A skin condition analysis program that allows the melanin index to be obtained from the second absorbance. An inter-wavelength absorption coefficient ratio calculation unit is formed in the skin condition analysis unit, and the inter-wavelength absorption coefficient ratio calculation unit includes the second-equal extinction coefficient with respect to the extinction coefficient of oxyhemoglobin at the first-equal extinction coefficient ratio wavelength. The ratio of the extinction coefficient at the specific wavelength or the ratio of the extinction coefficient at the second extinction coefficient ratio wavelength to the extinction coefficient of deoxyhemoglobin at the first extinction coefficient ratio wavelength is calculated, and the melanin is calculated. The index calculation unit is allowed to multiply the apparent first extinction measured when the skin is irradiated with light containing the first extinction coefficient ratio wavelength, which is the shorter wavelength, by the inter-wavein absorption coefficient ratio. Then, the melanin index is obtained by subtracting the apparent second extinction measured when the skin is irradiated with light containing the second extinction coefficient ratio wavelength, which is the longer wavelength. 11. The skin condition analysis program according to 11. It is a calculation method of the erythma index that calculates the erythma index that reflects the amount of hemoglobin contained in the skin in order to evaluate the condition of the skin .
The erythma index is the ratio of the extinction coefficient on the extinction coefficient spectrum of oxyhemoglobin to the extinction coefficient on the extinction coefficient spectrum of deoxyhemoglobin. As the extinction coefficient ratio wavelength and the second extinction coefficient ratio wavelength, the apparent first absorbance measured when the skin is irradiated with light including the first extinction coefficient ratio wavelength and the second extinction coefficient ratio wavelength are used. A method for calculating the erythma index, which is obtained from the apparent second absorbance measured when the skin is irradiated with the contained light.

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