The present invention relates to a method for evaluating the cosmetic effects of a cosmetic product
on the skin.
10 BACKGROUND ART
Recently, some methods for measuring the cosmetic effects of a cosmetic product have been
developed. For examples, JP-A-2007-307084 discloses a method for evaluating the whitening
effect by measuring an increase in whiteness of skin color due to a skin color change caused by
15 promoted blood circulation. The whitening effect is determined by the increase rate of the
average hemoglobin content in this method.
JP-A-2008-245666 discloses a method for evaluating skin pigmentation comprising a step of
obtaining a color image of a color chart for adjusting a white balance by using a camera. This
20 method is based on RGB information which provides a color image and conventional color
parameters which do not teach homogeneity of skin color and pigmentary spots.
However, consumer perception is very complex and thus multi instrumental parameters are often
used to understand what consumers feel and think. Also, the results obtained by current
25 technologies are not precise enough to understand consumers' needs.
The conventional methods for evaluating the cosmetic effects of a cosmetic product are based
primarily on color information by a spectrum or average spectrum of an area. However,
discrepancies may be found with customer perception in the cosmetic application by methods
30 based on color analysis.
On the other hand, a hyperspectral imaging method coupled with spectral angle map fractal
analysis has been developed for a method and an apparatus for a non-invasive measurement of
human skin melanin. For example, JP-A-20 10-51589 discloses a non-invasive method for
35 measuring the amount of melanin in human skin. JP-A-2010-125288 discloses a method for
creating images for melanoma diagnosis by using spectral analysis in a non-invasive manner.
JP-A-2010-252904 discloses a method for deriving an index for discriminating melanoma using a
spectra analysis.
40 The hyperspectral imaging method has numerous advantages. For example, the method is
non-invasive, non-contact and enables swift measurement. In addition, information on the
molecular level can be obtained by the method.
The hyperspectral imaging method has been mainly focused on the biomedical field for the
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purpose of pre-diagnostics application of superficial cancer and images oflentigo malignant
melanoma. However, the hyperspectral imaging method has not been investigated in the
cosmetic field so far.
DISCLOSURE OF INVENTION
An objective of the present invention is to provide a new method for evaluating the cosmetic
effects of a cosmetic product on the skin with high precision and accuracy. Another objective is
to provide new indices directly linked to customer perception.
The above objectives of the present invention can be achieved by a method for evaluating the
cosmetic effects of a cosmetic product on the skin, comprising steps of:
(i) measuring diffuse reflection spectrum at the surfaces of a reference and an object skin before
an application to acquire positional information at the surfaces of the reference and the object skin,
15 and pixel data including the diffuse reflection spectrum at the pixel,
(ii) applying the cosmetic product to the surface of the object skin,
(iii) measuring diffuse reflection spectrum at the surfaces of the object skin after the application to
acquire positional information at the surfaces of the object skin, and pixel data including the
diffuse reflection spectrum at the pixel,
20 (iv) determining multi-dimensional vectors from the diffuse reflection spectrum at the surfaces of
the reference and the object skin before and after the application,
(v) evaluating the cosmetic effects of the cosmetic product by comparing any indices of relative
spectral lengths of the object skin, spectral angles and an entropy after the application of the
cosmetic product to the indices before the application of the cosmetic product,
25 wherein
the average spectral lengths of the object skin relative to the spectral length ofthe reference before
and after the application are determined from the multi-dimensional vectors of the object skin
before and after the application using the reference vector,
the spectral angles are determined from the multi-dimensional vectors ofthe reference and the
30 object skin before and after the application using the reference vector, and
the entropy is determined from the spectral angles, the positional information and the pixel data.
The multi-dimensional vectors of the reference and the object skin before and after the application
in the step (iv) may be determined by vectors whose components are the diffuse reflectances at
35 wavelength bands at the pixel.
40
The relative spectral lengths of the object skin before and after the application ( f sb and f sa) in
step (v) can be determined by the following equations:
L
f =~
sb L '
r
f = Lsa
sa L
r
(1)
(2)
2
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wherein
Lr is the average length of the multi-dimensional vectors of the reference,
Lsb is the average length of the multi-dimensional vectors of the object skin before the application,
and
5 Lsa is the average length ofthe multi-dimensional vectors of the object skin after the application,
wherein
(3)
(4)
(5)
lO wherein
a/ is the diffuse reflectance component at the i-th wavelength band ofthej-th pixel ofthe
reference,
b; is the diffuse reflectance component at the i-th wavelength band ofj-th pixel ofthe object skin
before the application,
15 c( is the diffuse reflectance component at the i-th wavelength band ofj-th pixel of the object skin
after the application,
n is the total number of wavelength bands, and
N is the total number of pixels.
20 The spectral angles before the application (Bbj) and those after the application (Bi) at the j-th pixel
in step (v) can be determined by the following equations:
. l
e~ =cost
(_!_ i>~ )bt
i=l N m=l (6)
8j =COS-I
a
n ( J N ) I-L:a~'cf
i=l N m=l
LO r sa
(7)
wherein
25 U is the length ofthe multi-dimensional vector at the j-th pixel of the reference,
Ls~ is the length of the multi-dimensional vector at the j-th pixel of the object skin before the
application,
Lsi is the length of the multi-dimensional vector at the j-th pixel of the object skin after the
application,
30 eJ is the spectral angle at the j-th pixel of the object skin before the application,
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ej is the spectral angle at the j-th pixel of the object skin after the application,
aim is the diffuse reflectance component at the i-th wavelength band ofm-th pixel of the reference,
b! is the diffuse reflectance component at the i-th wavelength band of the j-th pixel of the object
skin before the application,
5 c! is the diffuse reflectance component at the i-th wavelength band of the j-th pixel of the object
skin after the application,
n is the total number of wavelength bands, and
N is the total number of pixels.
10 The entropy before and after the application in step (v) can be determined by the following
equations:
K
epy b =-L n.(8b.k )log2 n.(8b.k)
k=O
K
epya =-Ln.(8a.k)log2 n(8a.k)
k=l
wherein
15 epyb is the entropy before the application,
epya is the entropy after the application,
n(8b,k) = (n(8b,k )- n(8b,k-J); N
n(8a,k) = (n(8a,k )- n(8a,k-J); N
wherein
(8)
(9)
(10)
(11)
20 n(8b,k) is the number of pixels with the corresponding spectral angles less than 8b,k,
n(8a,k) is the number of pixels with the corresponding spectral angles less than 8a,k, and
N is the total number of pixels
wherein
k18 -8 . ) 8 = '\ a,max a,mm k = 0 1 2 ... K
a,k K ' '' ' ' '
25 K is the total number of segments between 8 a,min = min(8~) and
e a,max = max(e;) with a = b, a .
A wavelength of the diffuse reflection spectrum may be in the range of 450 to 750 nm.
30 The reference may be the skin of inner arms.
The object skin may be the skin of a face.
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The cosmetic product may be for a topical application.
The cosmetic product for the topical application can be a skin care product, a makeup product for
5 the skin, or a sun protection product.
10
The skin care product can be selected from the group consisting of a cleanser, a lotion, a cream, a
gel, a facial mask, a skin lightener, a skin whitener, and a serum. The skin care product can be
for skin lightening, skin whitening, skin bleaching or self-tanning.
The method according to the present invention can be non-invasive.
The method according to the present invention can be for evaluating a lightening or whitening
effect, for evaluating a protective effect against ultraviolet radiation and for evaluating a makeup
15 effect.
20
25
BRIEF DESCRIPTION OF DRAWINGS
Figure 1 shows a schematic diagram of an example of an apparatus used in the present invention.
Figure 2 shows a block diagram of a spectrometer which is mounted on the apparatus shown in
Figure 1.
BEST MODE FOR CARRYING OUT THE INVENTION
After diligent research, the inventors have discovered that it is possible to provide a method for
evaluating the cosmetic effects of a cosmetic product on the skin with high precision and accuracy,
and to provide new indices directly linked to customer perception.
30 The method according to the present invention can provide accurate analytical results by
considering the spectral angles and spectral lengths in correlation with skin color tone so that
accurate information on the homogeneity of skin color and the effect ofwhitening cosmetic
products can be obtained. The method can achieve an increase in data quality so that consumer
perception can be understood precisely due to the parameters from the spectral angles and spectral
35 lengths.
ln addition, the method according to the present invention has advantageous effects as follows: the
device used for the method according to the present invention provides a fast data acquisition time,
lower data-fluctuation during the time course, and a lower failure-frequency. The software for
40 the method according to the present invention provides an operator-friendly interface, easy
navigation for positioning, an automated calibration, and a malfunction indicator.
Hereinafter, the method for evaluating the cosmetic effects of a cosmetic product on the skin
according to the present invention will be explained in more detail.
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[Method for Evaluating Cosmetic Effects]
The method for evaluating the cosmetic effects of a cosmetic product on the skin according to the
5 present invention comprises the steps of:
(i) measuring diffuse reflection spectrum at the surfaces of a reference and an object skin before
an application to acquire positional information at the surfaces of the reference and the object skin,
and pixel data including the diffuse reflection spectrum at the pixel,
(ii) applying the cosmetic product to the surface of the object skin,
10 (iii) measuring diffuse reflection spectrum at the surfaces of the object skin after the application to
acquire positional information at the surfaces of the object skin, and pixel data including the
diffuse reflection spectrum at the pixel,
(iv) determining multi-dimensional vectors from the diffuse reflection spectrum at the surfaces of
the reference and the object skin before and after the application,
15 (v) evaluating the cosmetic effects of the cosmetic product by comparing any indices of relative
spectral lengths of the object skin, spectral angles and an entropy after the application of the
cosmetic product to the indices before the application of the cosmetic product,
wherein
the average spectral lengths of the object skin relative to the spectral length ofthe reference before
20 and after the application are determined from the multi-dimensional vectors of the object skin
before and after the application using the reference vector,
25
the spectral angles are determined from the multi-dimensional vectors of the reference and the
object skin before and after the application using the reference vector, and
the entropy is determined from the spectral angles, the positional information and the pixel data.
In the steps (i) and (iii), diffuse reflection spectrum at the surfaces of a reference and an object
skin before and after the application are measured to acquire positional information at the surfaces
of the reference and the object skin, and pixel data including the diffuse reflection spectrum at the
pixel. The diffuse reflection spectrum obtained in the steps (i) and (iii) are related to the
30 wavelength in the two-dimensional plane.
In order to utilize the information at the molecular level, the wavelength of the diffuse reflection
spectrum is preferably in the range of 450 to 750 nm, more preferably in the range of 500 to 750
nm which is a visible- near infrared spectrum. The visible- near infrared spectrum includes the
35 information of components at the molecular level that constitutes the object.
In the measurement of the diffuse reflection spectrum, all predetermined spatial regions may be
scanned. Therefore, there is a possibility that unnecessary pixel data will also be acquired.
Consequently, preferably, after acquiring the pixel data, the pixel data having a predetermined
40 reflectivity at a given wavelength should be excluded by filtering.
The reference used in the method according to the present invention is preferably the skin of inner
arms.
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In the step (iv), multi-dimensional vectors from the diffuse reflection spectrum at the surfaces of
the reference and the object skin before and after the application are determined. The
multidimensional vectors of the reference and the object skin before and after the application can
be determined by vectors whose components are the diffuse reflectances at wavelength bands at
5 the pixel.
10
15
20
In the step (v), the cosmetic effects of the cosmetic product are evaluated by comparing any
indices of relative spectral lengths ofthe object skin, spectral angles and an entropy after the
application of the cosmetic product to the indices before the application of the cosmetic product.
The relative spectral lengths and the spectral angles are calculated by Spectral Angle Mapper
(SAM) described in F. A. Kruse et al., "The spectral image processing system (SIPS) - interactive
visualization and analysis of imaging spectrometer data", (1993) Remote Sensing ofEnvironment,
44, pp. 145-163.
The relative spectral lengths of the object skin before and after the application ( e sb and e sa) in
step (v) can be determined from the multi-dimensional vectors. These lengths indicate the
change in net light absorption caused by change in melanin content in the skin. The relative
spectral lengths can be determined by the following equations:
wherein
£ = Lsb
sb L '
r
e = Lsa
sa L
r
(1)
(2)
Lr is the average length of the multi-dimensional vectors of the reference,
Lsb is the average length of the multi-dimensional vectors of the object skin before the application,
25 and
30
Lsa is the average length of the multi-dimensional vectors of the object skin after the application,
wherein
(3)
(4)
(5)
wherein
a! is the diffuse reflectance component at the i-th wavelength band ofthe j-th pixel of the
reference,
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b( is the diffuse reflectance component at the i-th wavelength band ofj-th pixel of the object skin
before the application,
c; is the diffuse reflectance component at the i-th wavelength band ofj-th pixel of the object skin
after the application,
5 n is the total number of wavelength bands, and
N is the total number of pixels.
The longer the relative spectral lengths are, the more reflectances are acquired from the skin.
10 The spectral angles before the application (8bj) and after the application (8i) at the j-th pixel in step
(v) can be determined from inner products of the multi-dimensional vectors. These spectral
angles indicate the qualitative change in spectrum characteristics between the reference and the
object skin at a molecular level, such as differences in the ratio of constituents in the skin due to a
change in balance between melanin and hemoglobin amounts. These spectral angles can be
15 determined by the following equations:
8~ =COS-I
f(_!__ i>~)bl
i=l N m=l (6)
8j =COS-I
a (7)
wherein
L) is the length of the multi-dimensional vector at the j-th pixel of the reference,
20 LsJ is the length of the multi-dimensional vector at the j-th pixel of the object skin before the
application,
Lsl is the length of the multi-dimensional vector at the j-th pixel of the object skin after the
application,
ebj is the spectral angle at the j-th pixel of the object skin before the application,
25 ej is the spectral angle at the j-th pixel of the object skin after the application,
at is the diffuse reflectance component at the i-th wavelength band ofm-th pixel ofthe reference,
b( is the diffuse reflectance component at the i-th wavelength band of the j-th pixel of the object
skin before the application, Cc; is the diffuse reflectance component at the i-th wavelength band of the j-th pixel of the object
30 skin after the application,
35
n is the total number of wavelength bands, and
N is the total number of pixels.
The smaller the spectral angles are, the closer to the reference the object skin is.
The entropy is one of the indices reflecting molecular information at the surface of the object skin.
8
5
10
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This entropy indicates the width of spectral angle distribution associated with homogeneity of the
skin. The entropy before and after the application in step (v) can be determined by the following
equations:
K
epyb =-L:n(eb,k)log2 n(eb,k)
k=O
K
epya =-L:n(ea,k)log2 n(ea,k)
k=l
wherein
epyb is the entropy before the application,
epya is the entropy after the application,
n(eb,k) = (n(eb,k )- n(eb,k-1 ))1 N
n(ea,k) = (n(ea,k)- n(ea,k-1))1 N
wherein
(8)
(9)
(10)
(11)
n(eh,k) is the number of pixels with the corresponding spectral angles less than eb,k,
n(ea,k) is the number of pixels with the corresponding spectral angles less than ea,k, and
N is the total number of pixels
15 wherein
k(8a,max -8a,min) -------''-------'------'-----'- , k = 0, 1, 2,- · ·, K ,
K
K is the total number of segments between ect,min = min(eU and
e a,min = max(e~ ) with a = b, a.
20 The smaller the entropy is, the more homogeneous the color of the skin is.
By setting a threshold value for spectral angles and the percentage in the spectral angle
distribution, spots of no interest can be excluded from analysis. The spectral angles of the object
skin should be smaller than the threshold value, so that ifthere are spots having a higher threshold
25 value with a certain percentage, they will be excluded from the target spots.
The method according to the present invention can be used for the application of skin color
analysis and color analysis of cosmetic products by determining ( l) the differences before and
after an application, and (2) the differences immediately after the application and after any
30 numbers ofhours of the application ofthe cosmetic products.
The method according to the present invention is a beneficial evaluation tool that provides
9
5
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accurate analytical results by considering spectral angles and spectral lengths in correlation with
the object skin color tone. The method can achieve an increase in data quality for precise
understanding of consumers' perception using the parameters from the spectral angles and spectral
lengths.
[Cosmetic Product]
In step (ii) ofthe method according to the present invention, a cosmetic product is applied to the
surface of the object skin. The object skin is preferably the skin of a face.
The cosmetic product used in the present invention is preferably for a topical application. The
cosmetic product for the topical application may be a skin care product, a makeup product for the
skin, or a sun protection product.
15 The skin care product is not limited specifically, and can be selected from the group consisting of
a cleanser, a lotion, a cream, a gel, a facial mask, and a serum. The skin care product can be for
skin lightening, skin whitening, skin bleaching or self-tanning.
The skin lightener and the skin whitener are compositions for applying to the surface of the body
20 of a human being for the purpose of lightening or whitening, and are preferably cosmetics or
agents for topical application on the skin. Cosmetics or agents for topical application on the skin
means a product to be applied onto the skin, and may correspond to a dermatological drug or quasi
drug. The terms "lightening" and "whitening" mean all effects of inhibiting the production
and/or deposition of melanin, and include inhibiting of the production of melanin, and reducing
25 the produced melanin.
In the case of the skin lightener or the skin whitener being a cosmetic water, the cosmetic water is
preferably transparent or preferably has a uniform outer appearance. Here, the expression
"transparent" means a transilluminating property without any deviation caused due to refraction or
30 reflection. Transparency of a composition such as a cosmetic water can be measured by means
of a turbidimeter. For example, a portable turbidimeter model 2100 P (trade name) manufactured
by Hach Company can be employed in order to measure the transparency limit of a composition.
When a composition has a measured turbidity value ranging from 0 to 250 NTU, the composition
can be considered as being transparent.
35
The skin lightener or the skin whitener is employed in a cosmetic treatment process comprising
the step of applying the skin lightener or the skin whitener onto the skin. The process is, in
particular, suitable for removing brownish pigmentation blemishes, for example, caused by
external factors, and/or blemishes caused by, for example, internal factors such as aging and the
40 like, and/or is suitable for lightening the brown skin.
The cosmetic product used in the present invention may be in the form of a suspension, a
dispersion; an oil-in-water, water-in-oil or multiple emulsion; a gel or a mousse; an oily or
emulsified gel; a dispersion of vesicles, especially lipid vesicles; a two-phase or multi-phase
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lotion; a spray; a loose, compact or cast powder; an anhydrous paste. The cosmetic product may
have the appearance of a lotion, a cream, a pomade, a soft paste, an ointment, a mousse, a cast or
molded solid, or a compacted solid.
5 The cosmetic product may also be in the form of a composition for protecting or caring for the
skin of the face, the neck, the hands or the body.
The cosmetic product used in the present invention can comprise components typically employed
in cosmetics, such as acids, bases, salts, pigments, antioxidants, UV absorbing agents, blood
10 circulation accelerators, metal chelators, sebum controllers, powders, astringents, skin softeners,
humectants, surfactants, oils, organic solvents, silicones, silicone derivatives, natural extracts
derived from animals or vegetables, waxes, and the like.
15
[Apparatus]
The apparatus used in the present invention will be described with reference to Figures 1 and 2.
In Figure 1, l is the subjectS. 2 is a white light source, and spectrometer 4 with a slit 3 is
integrated with the CCD camera 5. Spectrometer 4 is an imaging spectrometer equipped with a
transmission grating. The light reflected from the one line of the measurement object passes
20 through the slit 3, is imaged on a light receiving surface ofthe CCD camera 5 serving as the
detector, and is dispersed by the spectrometer. That is, the X-axis of the light receiving surface
of the CCD camera 5 corresponds to the position of one line of the measurement object, and the
Y-axis direction is the spectrum of the light dispersed.
25 The detailed structure of spectrometer 4 is shown in Figure 2. Slit 3 is composed of a lens 3b to
condense light and the slit body 3a. In addition, spectrometer 4 is composed of a prism 4b of the
transmissive grating system which is between two lens 4a and 4c. Using an EM (Electron
Multiplying) CCD camera, CCD camera 5 enhances the sensitivity to even weak light.
30 Since the optical part of the apparatus is configured as stated above, the diffuse reflection
spectrum data of one line of the objectS can be obtained from one frame of the CCD camera.
This data is input to the data processing device 6. Then, to get to the next frame of the CCD
camera, the optical part ofthe apparatus is moved at a short distance and the diffuse reflection
spectrum data of the next line is sent to the data processing device 6. By repeating this operation,
35 it is possible to obtain diffuse reflectance spectral data of a two-dimensional plane. In fact, by
the mechanism which moves in the direction perpendicular to the one line of the measurement
object surface corresponding to the X-axis such as control unit 6b, the optical part is moved
substantially continuously, and the data is acquired synchronously by the CCD camera 5.
40 Although not shown, the apparatus used in the present invention is provided with a pair of
polarizing plates. The light from the white light source 2 is linearly polarized by the polarizing
plate, and only the perpendicular linearly polarized light component from the white light source 2
is incident on the spectrometer 4. Thus, the influence of irregular reflection occurring at the
surface of the objectS is suppressed. In addition, the direction of the polarizing plate can be set
wo 2014/204007 PCT /JP2014/066493
freely.
Although not shown, the apparatus used in the present invention has an Automatic focus (AF)
function which can always focus on the center of the measuring point. Accordingly, the effects
5 of shadows caused by large irregularities in the frequency space relatively on the surface of the
object S can be suppressed.
The apparatus used in the present invention can store the diffuse reflection spectrum in the
wavelength band that is determined by the characteristics of the spectrometer 4 in a
10 two-dimensional image in each pixel. The basic length scale of the two-dimensional image is
determined by the measurement screen vertical dimension determined by an optical slit length of
the slit 3 and the optical system magnification of the spectrometer 4, the measurement lateral
screen dimension determined by the optical slit width of the slit 3 and the drive software setting of
the control means 7, the one pixel dimension of the CCD camera 5, and the one pixel dimension
15 determined by the optical slit width of the slit 3 and the optical system magnification of
spectrometer 4. Information on the position and diffuse reflection spectrum can be acquired in a
short time by line scanning perpendicular to the longitudinal direction of the optical slit.
Analysis ofthe diffuse reflection spectrum of the target object obtained makes it possible to draw
a two-dimensional spectral image. Therefore, it is possible to highlight the area where there is a
20 qualitative or quantitative difference optically in the diffuse reflection spectrum with the apparatus.
25
It is also possible to reconfigure the pseudo-color image by calculating and drawing the three
primary colors element value from the diffuse reflectance spectrum.
[Cosmetic Application]
The method according to the present invention can be used for various applications. For
example, the method can be used for evaluating a lightening or whitening effect of a cosmetic
product such as a skin lightener and a skin whitener on the skin.
30 The method according to the present invention can also be used for evaluating a protective effect
against ultraviolet radiation of a sun protection product on the skin.
35
40
The method according to the present invention can also be used for evaluating a makeup effect of
a makeup product for the skin.
EXAMPLES
The present invention will be described in a more detailed manner by way of examples.
However, they should not be construed as limiting the scope of the present invention.
[Apparatus]
A hyperspectral imaging device (MSI-03, Mitaka Kohki Co., Ltd., Tokyo, Japan) was used for this
study. The details of this apparatus are as follows:
12
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Spectral resolution: 1.51 nm,
Spectral range: 450.23-749.95 nm,
Measurement area: 16.09 mm x 21.52 mm,
Spatial resolution: 32.7 J..lm,
PCT /JP2014/066493
5 Measurement time: about 10 s,
Power of light source: 150 W,
10
Total number of wavelength bands (n): 199
Total number of pixels (N): 323736
Total number of segments (K): 80
[Reference and Object for Evaluation]
An inner arm of one person is used as a reference for the measurements. A diffuse reflection
spectrum at the surface of the inner arm is measured to acquire positional information at the
15 surface of the inner arm, and pixel data including the diffuse reflection spectrum at the pixel.
20
30 models who had solar lentigos on both sides of their faces were selected by a dermatologist.
[Protocol for Evaluation]
Two products (One is a whitening product with active and the other is a placebo, i.e. a product
without active) were applied to the left and right side of the faces of the models for 8 weeks. The
models washed their faces with standard cleansing procedures every morning and evening. The
application side was randomly selected for each model. During the test period, the models were
25 prohibited to use any other serum. The rest of the skincare and makeup items they used
normally were kept in their beauty routine.
The diffuse reflection spectrums at the surfaces of the skins of the faces were measured before the
test (TO) and after 8 weeks (T8). Relative spectral lengths, spectral angles and entropies after the
30 application ofthe whitening product were determined from the diffuse reflection spectrum at the
surfaces of the reference and the skin of the faces before and after the application.
[Results]
· 35 Average spectral lengths, average spectral angles and entropy were determined from the
multi-dimensional vectors, and these indices for the whitening product and the placebo are shown
in Tables 1 and 2. The values shown are averages for 30 models.
Table 1 Cosmetic product without active (Placebo) at TO and T8
40
TO T8
Entropy 3.1 ± 0.6 3.0±0.7
Averaged spectral angle 3.8 ± 1.9 3.6± 1.6
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I Averaged spectral length 1.0± 0.1 1.0± 0.1
Table 2 Cosmetic product with active at TO and T8
TO T8
Entropy 3.1 ± 0.6 3.0±0.5
Averaged spectral angle 3.8 ± 1.6 3.5 ± 1.5
Averaged spectral length 1.0 ± 0.1 1.0± 0.1
5 The differences in average spectral lengths, average spectral angles and entropy between TO and
T8 calculated from the values in Tables 1 and 2 are shown in Table 3.
10
Table 3 Difference between Placebo and Whitening Product, T8 -TO
Placebo
Whitening
Product
Entropy 0.01 ± 0.29 -0.08 ± 0.29
Averaged spectral angle -0.06 ± 0.90 -0.40± 0.95
Averaged spectral length 0.01 ±0.05 0.01 ±0.06
Comparing the results of the placebo and those of the whitening product, entropy and average
spectral angle are decreased significantly. These results show that the target skin of the face is
whitened by the whitening product.
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CLAIMS
A method for evaluating the cosmetic effects of a cosmetic product on the skin,
comprising steps of:
(i) measuring diffuse reflection spectrum at the surfaces of a reference and an
object skin before an application to acquire positional information at the
surfaces ofthe reference and the object skin, and pixel data including the
wherein
diffuse reflection spectrum at the pixel,
applying the cosmetic product to the surface of the object skin,
measuring diffuse reflection spectrum at the surfaces of the object skin after the
application to acquire positional information at the surfaces of the object skin,
and pixel data including the diffuse reflection spectrum at the pixel,
determining multi-dimensional vectors from the diffuse reflection spectrum at
the surfaces of the reference and the object skin before and after the application,
evaluating the cosmetic effects of the cosmetic product by comparing any
indices of relative spectral lengths ofthe object skin, spectral angles and an
entropy after the application of the cosmetic product to the indices before the
application ofthe cosmetic product,
the average spectral lengths of the object skin relative to the spectral length of the
reference before and after the application are determined from the multi-dimensional
vectors ofthe object skin before and after the application using the reference vector,
the spectral angles are determined from the multi-dimensional vectors of the reference
and the object skin before and after the application using the reference vector, and
the entropy is determined from the spectral angles, the positional information and the
pixel data.
The method according to Claim 1, characterized in that the multi-dimensional vectors of
the reference and the object skin before and after the application in the step (iv) are
determined by vectors whose components are the diffuse reflectances at wavelength
bands at the pixel.
3. The method according to Claim 1 or 2, characterized in that the relative spectral lengths
of the object skin before and after the application ( f sb and e sa) in step (v) are
determined by the following equations:
f = Lsb
sb L '
wherein
r
f = Lsa
sa L
r
Lr is the average length of the multi-dimensional vectors of the reference,
wo 2014/204007 PCT /JP2014/066493
Lsb is the average length of the multi-dimensional vectors of the object skin before the
application, and
Lsa is the average length ofthe multi-dimensional vectors ofthe object skin after the
application,
wherein
wherein
ai is the diffuse reflectance component at the i-th wavelength band of the j-th pixel of the
reference,
b( is the diffuse reflectance component at the i-th wavelength band ofj-th pixel of the
object skin before the application,
ci is the diffuse reflectance component at the i-th wavelength band ofj-th pixel of the
object skin after the application,
n is the total number of wavelength bands, and
N is the total number of pixels.
The method according to any one of Claims 1 to 3, characterized in that the spectral
angles before the application (8bj) and after the application (8j) at the j-th pixel in step (v)
are determined by the following equations:
Ln -( L1 aN ~b) t
i=l N m=l (6)
Ln -( L1a N~ 'c) f
i=l N m=l (7)
wherein
I) is the length of the multi-dimensional vector at the j-th pixel of the reference,
Lsbj is the length of the multi-dimensional vector at the j-th pixel of the object skin
before the application,
Lsi is the length ofthe multi-dimensional vector at the j-th pixel of the object skin
after the application,
ebj is the spectral angle at the j-th pixel of the object skin before the application,
wo 2014/204007 PCT /JP2014/066493
ej is the spectral angle at the j-th pixel of the object skin after the application,
at is the diffuse reflectance component at the i-th wavelength band ofm-th pixel of the
reference,
b( is the diffuse reflectance component at the i-th wavelength band ofthej-th pixel ofthe
object skin before the application,
c( is the diffuse reflectap.ce component at the i-th wavelength band of the j-th pixel of the
object skin after the application,
n is the total number of wavelength bands, and
N is the total number of pixels.
5. The method according to any one of Claims I to 4, characterized in that the entropy
before and after the application in step (v) is determined by the following equations:
K
epy b =-2: n(8b,k )log2 n(8b,k)
k=O
K
epya =-2:n(8a,k)log2 n(8a,k)
k=l
wherein
epyb is the entropy before the application,
epya is the entropy after the application,
n(8b,k) = (n(8b,k )- n(8b,k-,))1 N
n(8a,k) = (n(ea,k)- n(ea,k-J); N
wherein
n(8b,k) is the number of pixels with the corresponding spectral angles less than 8b k,
n(8a,k) is the number of pixels with the corresponding spectral angles less than Ba k,
and
N is the total number of pixels
wherein
k1 B = ~8 -8 . ) a,max a,mm k = 0 1 2 ... K
a,k K , '', , '
K is the total number of segments between 8 a,min = min(8~) and
e a,min = max(e~) with a = b, a.
30 6. The method according to any one of Claims l to 5, characterized in that a wavelength of
the diffuse reflection spectrum is in the range of 450 to 750 nm.The method according to any one of Claims 1 to 6, characterized in that the reference is the skin of inner arms.
The method according to any one of Claims 1 to 7, characterized in that the object skin is the skin of a face.
The method according to any one of Claims 1 to 8, characterized in that the cosmetic product is for a topical application.
The method according to Claim 9, characterized in that the cosmetic product for the topical application is a skin care product, a makeup product for the skin, or a sun protection product.
The method according to Claim 10, characterized in that the skin care product is selected from the group consisting of a cleanser, a lotion, a cream, a gel, a facial mask, and a serum.
The method according to any one of Claims 1 to 11, characterized in that the method is non-invasive.
The method according to any one of Claims 1 to 12, characterized in that the method is for evaluating a lightening or whitening effect.
The method according to any one of Claims 1 to 12, characterized in that the method is for evaluating a protective effect against ultraviolet radiation.
The method according to any one of Claims 1 to 12, characterized in that the method is for evaluating a makeup effect