JP3349026B2 - Skin surface analysis device and skin surface evaluation method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for analyzing skin surface and a method for evaluating skin surface, and more particularly to quantifying the exfoliation state of a stratum corneum sampled using a stratum corneum sample sheet having an adhesive surface. And a skin surface evaluation method.

[0002]

2. Description of the Related Art It is very important to accurately grasp and evaluate skin properties and skin qualities in developing a main ingredient in cosmetics, especially basic cosmetics. Further, in the future, it will be necessary to evaluate from more various directions, and it will be important to grasp the skin condition in more detail.

[0003] As a method of evaluating the condition of the skin, an evaluation method by measuring the keratin water content, absorbed water retention ability, transdermal water evaporation, and the like using electrical conductivity and the like is generally used.

[0004] In recent years, as a method of evaluating the condition of the skin, an evaluation method using keratinocytes collected non-invasively has become important. As a method of non-invasively collecting the stratum corneum and evaluating the skin, a method called a tape stripping method using an adhesive tape is generally used. Conventionally, the skin condition is evaluated by staining the keratinocytes collected in this way and measuring the number of nucleated cells, cell area, shape factor, and the degree of delamination using an optical microscope. It was done. However, these methods have problems that the preparation of the sample is complicated and that observation under a microscope requires experience.

[0005] Recently, a technique has been developed in which the collected stratum corneum is evaluated at a macro level, not at a micro level as in the observation of corneocytes with a microscope. As a method therefor, there is a method in which a sheet having an adhesive surface is pressed against the skin surface to collect and collect keratin pieces on the adhesive surface and project this on a screen using a projection lens (Japanese Patent Laid-Open No. 63-1224).
No. 38) or a sheet having an adhesive surface is pressed against the skin surface to collect and collect keratin pieces from the adhesive surface, and irradiate the light from a light source to measure the amount of transmitted light to determine the amount of keratin layer attached. Method of measurement, a sheet having an adhesive surface is pressed against the skin surface, and keratin pieces are adhered and collected on the adhesive surface, and after staining, the color is measured with a color difference meter. Measurement method, press the sheet with the adhesive surface to the skin surface, adhere and collect the keratin pieces on the adhesive surface, paste this on black paper, take a picture of the keratin layer adhesion sheet, peel off to the image analyzer There is known a method of measuring the luminance after inputting the stratum corneum image and quantifying the amount of exfoliation of the stratum corneum.

[0006]

However, in the above method, since the image is an enlarged projection image on a screen, the image quality is unclear and it is difficult to clarify the difference between samples. Is impossible. Further, in the above method, it is considered that it is impossible to catch a subtle change only by the amount of light transmitted through the sheet, and it is also difficult to clarify the difference between the samples. Further, in the above method, it is very difficult to perform the same staining every time, and it is expected that the measurement result is considerably affected by the state of the staining. Further, since the exfoliated stratum corneum is not uniform, an error is considered to increase depending on the colorimetric site. In addition, in the above methods and the above methods, the quantification of the exfoliated stratum corneum can be performed by the light amount (Lux) or the colorimetric value. It is impossible to evaluate the exfoliated stratum corneum image that comes off.
In addition, the above method is to capture the image using scattered light, but in order to measure the thickness and amount of the exfoliated stratum corneum using the brightness value, the amount of stratum corneum adhered to the sheet This is inappropriate because it is necessary to use transmitted light whose light quantity increases and decreases correspondingly. Further, in this method, although the measured value of the peeling amount can be calculated to quantify the peeling amount, the fact is that it is not enough to quantify the peeling pattern.

In general, when the stratum corneum is peeled and collected by the tape stripping method, images of various patterns are obtained depending on the subject and the measurement site. Normally, the modulation that occurs inside the skin appears as it is in the stratum corneum, and in that case, the normal stratum corneum is not formed, but becomes apparent on the skin surface in the form of rough skin, etc. The pattern is considered to reflect the state inside the skin. Therefore, it is necessary to establish a method to accurately capture and quantify various patterns of the exfoliated stratum corneum,
It is indispensable to evaluate the condition inside the skin.

When the exfoliated stratum corneum was observed,
It has been found that these peeled stratum corneum patterns have two axes of a certain amount of peeling and uniformity. The present invention has been made in view of such circumstances, and has as its object to provide a skin surface analysis apparatus and a skin surface evaluation method for objectively and quantitatively quantifying the amount and uniformity of exfoliation of the stratum corneum. Is what you do.

[0009]

In order to achieve the above object, the present invention has the following arrangement. That is, the skin surface analyzing apparatus according to the present invention is a method of pressing the horny layer collection sheet having an adhesive surface to the subject's skin surface with a constant pressure and peeling off the horny layer on the skin surface with the adhesive surface of the horny layer collection sheet. Stratum corneum collecting means for attaching to the skin, imaging means for photographing the stratum corneum collecting sheet to which the stratum corneum has adhered with transmitted light, and processing the obtained exfoliated stratum corneum image, and measuring the luminance distribution to obtain the exfoliated stratum corneum Image analysis means for calculating the layer amount and calculating the image uniformity of the exfoliated stratum corneum thickness uniformity, the mass exfoliated stratum corneum size uniformity, the exfoliated stratum corneum positional uniformity, and the overall image uniformity And the thickness of the exfoliated stratum corneum
Oneness classifies the brightness value of the image into several levels,
Measure the number of pixels at the luminance level and calculate the total number of pixels
Analyzed by calculating each luminance level ratio in
The size uniformity of the massive exfoliated stratum corneum
The stratum corneum is exfoliated thickly by extracting high-brightness sites
Particles are obtained by highlighting and extracting the part that has
The size of the particle area into several levels
And the number of particles at each size level
By calculating each particle size level ratio in
Analyzed, the positional uniformity of the exfoliated stratum corneum
Is spread throughout the image so that each particle does not fuse
And measure the area of each diffused particle to reduce its variation.
It is analyzed by measuring, and the average of the entire image
One character divides the image into multiple blocks, and
Measure the amount of exfoliated stratum corneum of each block and measure the variation
It is characterized by being analyzed by measuring . Further, the skin surface evaluation method according to the present invention is a method for removing the horny layer collection sheet having an adhesive surface by pressing the skin surface of the subject at a constant pressure and peeling off the skin surface. The stratum corneum is attached by attaching the stratum corneum, photographing the stratum corneum-collecting sheet to which the stratum corneum is attached with transmitted light, processing the resulting peeled stratum corneum image, and measuring the luminance distribution to calculate the peeled stratum corneum amount. together, the thickness uniformity of the peeling stratum corneum, corneocytes bulk peel stratum corneum size uniformity,
Positional uniformity of the peeling the horny layer, the entire image is calculated image measurement values of uniformity, I skin surface evaluation method der to evaluate the state of the stratum corneum of the skin surface based on the calculation result, the release
The thickness uniformity of the stratum corneum allows the brightness value of the image to be
And classify the number of pixels at each luminance level.
To calculate each luminance level ratio for all pixels.
And the size uniformity of the massive exfoliated stratum corneum
However, by extracting the high brightness part of the above image,
Particles are obtained by highlighting and extracting the parts where
After measuring the particle area, several steps of the size of the particle area
And count the number of particles at each size level
And calculate the ratio of each particle size level in the total number of particles
And the positional uniformity of the exfoliated stratum corneum
However, the particles are drawn so that the particles do not fuse.
It diffuses throughout the image, measures the area of each diffused particle, and
Is analyzed by measuring the variation of
The uniformity of the whole image divides the above image into multiple blocks
Then, the exfoliated stratum corneum amount of each divided block was measured and measured.
It is analyzed by measuring the variation of
It is a method.

[0010] As described above, in the present invention, the exfoliated stratum corneum image is obtained by sampling the stratum corneum using the stratum corneum sampling sheet having an adhesive surface and photographing the stratum corneum with transmitted light. Therefore, the luminance value in this image is in correspondence with the actual exfoliated stratum corneum amount. Then, the image analysis unit measures the luminance distribution of this image, and also extracts the high-luminance part and performs particle analysis, thereby calculating the measured values of the exfoliated stratum corneum amount and the exfoliated stratum corneum uniformity. I can do it. Thus, according to the skin surface analyzing apparatus of the present invention, the pattern of the exfoliated stratum corneum can be objectively and quantitatively quantified in two parameters, the exfoliation amount and the uniformity, and the skin surface evaluation of the present invention According to the method, it is possible to clearly evaluate the state of the stratum corneum on the skin surface.

[0011]

Next, an embodiment of the present invention will be described. FIG. 1 is a block diagram showing a basic configuration of the skin surface analyzing apparatus according to the present invention. As shown in the figure, this apparatus comprises a stratum corneum collecting sheet 2 having an adhesive surface and a pressing device 1 for pressing the stratum corneum collecting sheet 2 against the skin surface.
And an imaging device 3 as an imaging means for capturing an image of the exfoliated stratum corneum adhered to the stratum corneum collecting sheet 2 and an image processing device / arithmetic device 8 as an image analysis means for analyzing the obtained image. ing.

The imaging device 3 includes an illumination light source 4 and a CCD.
It comprises an imaging tube 5, a signal conversion device 6, and a look-up table 7. The image processing device / arithmetic device 8 includes an image processor 9, a host computer 10, and an optical disk 11, and is connected to the imaging device 3.

In the thus constructed skin surface analyzing apparatus, the pressure-sensitive adhesive surface of the stratum corneum-extracting sheet 2 is brought into contact with a part (for example, cheek or the like) of the subject to be measured at a constant pressure by using a pressing instrument 1. Then, the stratum corneum on the skin surface is adhered to the adhesive surface of the stratum corneum collecting sheet 2. Then, the stratum corneum-collecting sheet 2 to which the stratum corneum is adhered is placed on the holder of the imaging device 3, and the measurement area is photographed by transmitted light. That is, the light from the illumination light source 4 passes through the stratum corneum sampling sheet 2, is subjected to photoelectric conversion by the CCD image pickup tube 5, is converted into RGB signals by the signal conversion device 6, and is inverted by the lookup table 7. Done. Next, the image processor 9 of the image processing device / arithmetic device 8 processes the image input from the imaging device 3 in the form of RGB signals. This image processor 9 has N
The image processor NEXUS6800 manufactured by EXUS is mainly used. The image processor 9
The input image is processed and measured, and the host computer 10 performs calculation processing, totalization, and the like of the measurement data from the image processor 9 by an analysis program, and performs system control of the entire apparatus.
The optical disk 11 records and stores the obtained image.

Next, the principle of capturing the exfoliated stratum corneum image by the imaging device 3 will be described with reference to FIG. That is, the stratum corneum collecting sheet 2 to which the exfoliated stratum corneum is adhered
By irradiating the light from the illumination light source 4 and transmitting the light through the stratum corneum-collecting sheet 2, a transmission image as shown on the left in FIG. Since this image was obtained by using transmitted light, the amount of the stratum corneum adhered to the image appeared somewhat as a shading of the image. Then, by inverting the black and white of the transmission image, a luminance inversion image as shown on the right side in FIG. In this inverted image,
The thicker the stratum corneum adheres, the higher the brightness is, and this inverted brightness image is used for measurement by image analysis described later.

Next, a method for measuring the amount of exfoliation of the stratum corneum will be described with reference to the flowchart of FIG. First, in step S1, the stratum corneum is collected on the stratum corneum collecting sheet 2 by the above-described method, and then, in step S2, the measurement area of the stratum corneum collecting sheet 2 to which the stratum corneum is adhered is photographed by transmitted light to thereby remove the stratum corneum. Get an image. Then, in step S3, this image is input to the image processor 9. The image processor 9 converts the captured image into 8-bit digital image data and captures it, and records and saves the image data on the optical disk 11.

The image input to the image processor 9 in this manner is a luminance-inverted image as described above. Therefore, the portion where the stratum corneum is thickly attached has higher luminance. Therefore, in step S4, a graph as shown in FIG. 4 can be obtained by measuring the luminance distribution of this image. Here, the luminance 0 is dark, and becomes brighter toward the luminance 255. Then, since the thickness of the stratum corneum and the brightness value are in a proportional relationship, in step S5, the exfoliated stratum corneum amount is calculated by the host computer 10 based on the following formula. Exfoliated stratum corneum amount = Σ luminance value × number of pixels

In order to confirm that the value of the exfoliated stratum corneum obtained as described above reflects the actual amount of exfoliated stratum corneum, a sample (n = 26) was actually collected. After measuring the weight of the stratum corneum adhering to the sheet with an electronic balance, the measured value of the exfoliated stratum corneum was measured. As a result, as shown in FIG. 5, it was confirmed that there was a high correlation between the exfoliated stratum corneum weight (μg) and the measured value of the exfoliated stratum corneum.

Next, a method for measuring the uniformity of the stratum corneum will be described with reference to the flowchart of FIG. First, as to steps S11 to S14, steps S1 to S14 described above with reference to the flowchart of FIG.
The process proceeds in the same manner as in the flow of Step 4. Next, in step S15, as shown in FIG. 7, the luminance value is divided into several levels (L0 to Ln), and the number of pixels at each luminance level is measured. Then, in step S16, each luminance level ratio (RL0 to RLn) in the total number of pixels is calculated. As described above, since the thickness of the stratum corneum is proportional to the luminance value, the luminance level ratio is used for analyzing the thickness uniformity of the stratum corneum.

In step S17, a binarization process or a threshold process is performed on the captured image to extract a high-luminance portion. The binarization process is a process performed by the image processor 9, and compares the brightness of each pixel of the image with a predetermined threshold to separate the image into two colors, white and black. That is, a portion where the stratum corneum is thick and exfoliated in a lump is emphasized and extracted, so-called particles are obtained.

Next, in step S18, the analysis of the particles, that is, the measurement of the area of each extracted particle is performed. Thereafter, in step S19, as shown in FIG. 8, the size of the particle area is divided into several levels (S1 to S
n) and count the number of particles at each size level. Then, in step S20, each particle size level ratio (RS1 to RSn) in the total number of particles is calculated. The particle size level ratio is used for analyzing the size uniformity of the stratum corneum.

In step S21, the particles in the image subjected to the binarization processing in step S17 are non-contact diffused by the image processor 9. That is, as shown in FIG. 9, diffusion is performed until the entire image is filled with particles so that the particles do not fuse. Next, in step S22, particle analysis is performed, and the area of each diffused particle is measured. Here, when the particles are present in the image in the form of aggregation, that is, in the state shown in the upper part of FIG. 9, the area of the particle is smaller in the aggregation portion and larger in the peripheral portion, The variation becomes large. Conversely, when the particles are scattered in the image, that is, when the state is as shown in the lower part of FIG. 9, the variation in the area of the particles becomes small. Thus, by measuring the variation in the area of each particle, the positional uniformity of the particles in the image can be known, and step S
In step 23, the standard deviation (SD) or coefficient of variation (CV) of each particle area is calculated by the host computer 10 to analyze positional uniformity.

In step S24, as shown in FIG. 10, the picked-up image is nxn (8.times.8 in FIG. 10).
Divided into Then, in step S25, the exfoliated stratum corneum amount of each block divided by the image processor 9 is measured using the above-described equation (Σluminance value × number of pixels). At this time, the greater the non-uniformity of the entire image, the greater the variation in the measured exfoliated stratum corneum amount values. Therefore, in step S26, the standard deviation (SD) or the coefficient of variation (C
V) is calculated by the host computer 10, and the uniformity analysis of the entire image is performed.

[0023]

EXAMPLES In order to evaluate the skin surface analyzing apparatus and the skin surface evaluation method according to the present invention, actual measurements were made, and the correlation between the measured data and various measured skin physiological parameters was examined. . As skin physiology parameters,
Stratum corneum moisture content (hereinafter, referred to as water content), absorbed water retention capacity (hereinafter, referred to as retention capacity), transdermal water evaporation (hereinafter, referred to as
TWL) and the measurement result of the amount of sebum were used.

The above-mentioned stratum corneum-extracting sheet is applied to the cheek (n = 30) of the female subject at a constant pressure (200 g) using a pressing device.
/ Cm ² ) for several seconds, followed by exfoliation to collect the stratum corneum. The stratum corneum-collecting sheet was set on an imaging device, and an image of an area of 12 mm × 12 mm in the adhesive surface of the sheet was taken. Then, after inverting the image luminance, the above-mentioned various measurement values were measured by the image processing device / arithmetic device.

The correlation between the various skin physiological parameters measured at the time of collecting the stratum corneum and the measured values of the uniformity of the exfoliated stratum corneum thickness measured by the image analysis was determined. The results are shown in Tables 1 and 2 below. In Table 1, skin physiological parameters having a high correlation with each luminance level ratio (L0 to L6)
In Table 2, skin physiological parameters having a high correlation with the ratio of each luminance level or more are displayed. In each table, the upper row shows the significance level, and the lower row shows the correlation coefficient.

Incidentally, each level was classified as follows.

[0027]

[Table 1]

[0028]

[Table 2]

Thus, the uniformity of the exfoliated stratum corneum thickness is
The correlation with the amount of water and the amount of sebum was high, and the amount of water showed a high correlation at L3 or L3 or higher. The sebum amount showed a high correlation at any level.

The correlation between the various skin physiological parameters measured at the time of collecting the stratum corneum and the measured value of the uniformity of the area size of the high-brightness site measured by the image analysis was determined. Here, the threshold was set to 51 and binarization was performed, and then the size of the extracted high-luminance portion area was measured. The results are shown in Tables 3 and 4 below. In Table 3, skin physiological parameters having a high correlation with each size level ratio (S1 to S8) are shown, and in Table 4, skin physiological parameters having a high correlation with a ratio of each size level or more are displayed. Each upper row shows the significance level, and the lower row shows the correlation coefficient.

After the binarization was performed by setting the threshold value to 51, the extracted high-luminance portion area size was classified into the following levels.

[0032]

[Table 3] Retention capacity unit: μS × min

[0033]

[Table 4]

As described above, the uniformity of the size of the high-brightness area has a high correlation with the water content and the holding ability.
High correlation was shown at the level of 1, S3 or S2 or higher. Also, the retention ability showed a high correlation at S3 or at a level of S3 or higher.

The correlation between the various skin physiological parameters measured at the time of collecting the stratum corneum and the positional uniformity measured value measured by the image analysis was determined. Here, the threshold value was set to 51, binarization was performed, and then the extracted particles were contactlessly diffused to measure the area of each particle. The results are shown in Table 5 below. In Table 5, skin physiological parameters highly correlated with the standard deviation (SD) of the extracted and non-contact diffused particles are displayed. The upper row shows the significance level, and the lower row shows the correlation coefficient.

[0036]

[Table 5]

As described above, the positional uniformity was correlated with the amount of water and the amount of sebum, and showed a particularly high correlation with the amount of sebum.

The correlation between the various skin physiological parameters measured at the time of collecting the stratum corneum and the measured uniformity of the entire image measured by the image analysis was determined. Here, 16 images
After the division into 64, the amount of peeling of each block was measured, and the variation was measured. The results are shown in Table 6 below.
Shown in In Table 6, skin physiological parameters highly correlated with the standard deviation (SD) of the exfoliated stratum corneum amount of each divided block are displayed. Each upper row shows the significance level, and the lower row shows the correlation coefficient.

[0039]

[Table 6]

As described above, the uniformity of the entire image depends on the amount of water,
There is a correlation with the amount of sebum, and in 64 divisions, TWL
High correlation.

[0041]

As described above, in the present invention, the exfoliated stratum corneum image is obtained by collecting a stratum corneum using a stratum corneum collecting sheet having an adhesive surface and photographing the stratum corneum with transmitted light. Therefore, the brightness value in this image corresponds to the actual exfoliated stratum corneum amount. Then, the image analysis unit measures the luminance distribution of this image, and also extracts the high-luminance part and performs particle analysis, thereby calculating the measured values of the exfoliated stratum corneum amount and the exfoliated stratum corneum uniformity. You can do it. Thus, according to the skin surface analysis apparatus of the present invention, the pattern of the exfoliated stratum corneum can be objectively and quantitatively quantified in two parameters, the exfoliation amount and the uniformity,
Further, according to the skin surface evaluation method of the present invention, it is possible to clearly evaluate the state of the stratum corneum on the skin surface.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a basic configuration of a skin surface analyzing apparatus according to the present invention.

FIG. 2 is a schematic diagram showing a transmitted image obtained by photographing the exfoliated stratum corneum with transmitted light and a black-and-white inverted image of the transmitted image.

FIG. 3 is a flowchart illustrating a method for measuring the amount of exfoliated stratum corneum according to the present invention.

FIG. 4 is a graph showing an example of a luminance distribution of a peeled stratum corneum image.

FIG. 5 is a graph showing a correlation between the measured value of the exfoliated stratum corneum obtained by image measurement and the actual exfoliated stratum corneum weight.

FIG. 6 is a flowchart illustrating a method for measuring the exfoliated stratum corneum uniformity according to the present invention.

FIG. 7 is a graph showing an example of level division by luminance.

FIG. 8 is a diagram showing an example of level division according to the size of extracted particles.

FIG. 9 is a diagram showing an example of non-contact diffusion of extracted particles.

FIG. 10 is a diagram showing an example in which a peeled stratum corneum image is divided into 64 (8 × 8).

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Pressing instrument 2 Stratum corneum extract sheet 3 Imaging device 4 Illumination light source 5 CCD imaging tube 6 Signal conversion device 7 Look-up table 8 Image processing device / arithmetic device 9 Image processor 10 Host computer 11 Optical disk

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int.Cl. ⁷ , DB name) G01N 33/48-33/98 A61B 5/00

Claims (2)

(57) [Claims] 1. A stratum corneum collecting means for pressing and peeling a stratum corneum collecting sheet having an adhesive surface onto a skin surface of a subject under a constant pressure to adhere a stratum corneum on the skin surface to the adhesive surface of the stratum corneum collecting sheet. And, an imaging means for photographing the stratum corneum collection sheet to which the stratum corneum adheres with transmitted light, and processing the obtained exfoliated stratum corneum image, and calculating the exfoliated stratum corneum amount by measuring the luminance distribution, Image analysis means for calculating image uniformity of exfoliated stratum corneum thickness uniformity, massive exfoliated stratum corneum size uniformity, exfoliated stratum corneum positional uniformity, and overall image uniformity The thickness uniformity of the exfoliated stratum corneum is
The brightness value of the image is divided into several levels, and
The number of pixels in each pixel
Analyzed by calculating the degree level ratio
The uniformity of the size of the exfoliated stratum corneum
By extracting, the part where the stratum corneum
After extracting the particles, the particle area is measured,
The size of the particle area is divided into several levels, and
Count the number of particles in the bell and count each particle in the total number of particles
Analyzed by calculating the size level ratio, the above
The positional uniformity of the exfoliated stratum corneum,
Particles diffused throughout the image to prevent coalescence and diffused
By measuring the area of each particle and measuring its variation
Analysis, and the uniformity of the entire image
Divide the image into multiple blocks and peel off each of the divided blocks.
By measuring the amount of stratum corneum and its variation
A skin surface analysis device characterized by being analyzed. 2. A horny layer on the skin surface is adhered to the adhesive surface of the horny layer-collecting sheet by pressing the horny layer-collecting sheet having an adhesive surface against the skin surface of the subject at a constant pressure and peeling off. The exfoliated stratum corneum sample sheet is photographed with transmitted light, the obtained exfoliated stratum corneum image is processed, and the luminance distribution is measured to calculate the exfoliated stratum corneum amount and the thickness of the exfoliated stratum corneum. Calculate the image uniformity, the size uniformity of the massive exfoliated stratum corneum, the positional uniformity of the exfoliated stratum corneum and the uniformity of the entire image, and evaluate the condition of the stratum corneum on the skin surface based on the calculation results It met the skin surface evaluation method to
The thickness uniformity of the exfoliated stratum corneum is determined by the brightness value of the image.
Is divided into several levels, and the pixel
Each bright level ratio in the total number of pixels to measure the Le number
Is analyzed by calculating the mass exfoliated stratum corneum
The size uniformity is to extract the high brightness part of the image
The exfoliated layer of the stratum corneum
Particles, and measure the area of this particle.
The size is divided into several levels, and for each size level
Count the number of particles and measure the size of each particle in the total number of particles
Analyzed by calculating the ratio, the exfoliated stratum corneum
Positional uniformity is achieved by fusing the particles with each other.
Diffused throughout the image so that the area of each diffused particle
Is analyzed by measuring the variation.
In addition, the uniformity of the entire image
Separated into locks and the amount of exfoliated stratum corneum of each divided block
Is analyzed by measuring the variation
A skin surface evaluation method comprising: