WO2011105731A2

WO2011105731A2 - System and method for measuring skin color

Info

Publication number: WO2011105731A2
Application number: PCT/KR2011/001154
Authority: WO
Inventors: 한지연; 남개원; 김은주; 김한곤; 김명준
Original assignee: (주)아모레퍼시픽
Priority date: 2010-02-26
Filing date: 2011-02-22
Publication date: 2011-09-01
Also published as: JP2013520274A; WO2011105731A3; KR20110098275A; JP5827249B2; KR101619342B1

Abstract

A skin color measurement system comprises: a transformation module which transforms the color of an image obtained by photographing a skin into color data in a log coordinate system having coordinate axes corresponding to primary colors; a first measurement module which disposes a preset illumination vector and a plurality of pigment vectors in a polygonal cone shape surrounding the color data, and measures a yellowish tone using the position of the vertex of the polygonal cone; and a second measurement module which separates the color data into the directional component of the illumination vector and the directional component of each of the pigment vectors, and measures a plurality of pigment distributions. With the skin measurement system, it is possible to measure a yellowish tone, a blackish tone and/or a reddish tone of a skin, and to output a result of the measurement as an image, and thus it is possible to simply and visibly express a change in a skin tone before and after a specific makeup product is used.

Description

【Specification】

[Name of invention]

Skin color measurement system and method

Technical Field

Embodiments relate to skin color measurement systems and methods.

Background Art

Techniques for measuring the texture or color of skin or for representing it as a computer image have been considered important functions in various imaging systems. In particular, with the development of mobile devices equipped with charge coupled devices (CCDs), beauty diagnosis systems, and telemedicine, technology for accurately measuring the texture or color of skin has been selected for cosmetics and cosmetics suitable for visual communication and skin. Increasingly, the utilization of medical diagnosis is increasing.

Conventional methods used to measure the texture or color of the skin include a method of extracting the distribution of melanin and hemoglobin present in the skin from an image photographed by the digital camera. For example, a method for extracting the distribution of melanin and hemoglobin from an image was published in the Journal of Optical Society of America in 1999 and published in "Independent component analysis of skin color image. And the method described in a paper by Tsumura et al.

However, in the case of using such a conventional method, it is impossible to measure the primary colors of different skins according to a person separately from the amount of pigment, and thus, when used in cosmetic diagnosis, it is difficult to accurately reflect the effects of cosmetic products. [Detailed Description of the Invention]

[Technical problem]

According to an aspect of the present invention, the skin can be measured from the yellow image representing the basic skin tone and black and red due to the pigment of the skin from the image of the skin, yellow and black skin and before and after the use of the cosmetic product It is possible to provide a system and method for measuring skin color that can be easily observed by displaying the change in red phase as an image.

[Technical Solution]

Skin color measurement system according to an embodiment, converts the color of the image taken by the skin to the color data on the logarithmic coordinate system having a coordinate axis that is the primary color Modles; First measurement modules for arranging a predetermined illumination vector and a plurality of pigment vectors in a polygonal pyramid shape surrounding the color data and measuring a yellow color using a vertex position of the polygonal pyramid; And a low) 2 measurement module for separating the color data into components in the illumination vector direction and components in the respective dye vector directions to measure a plurality of pigment distributions.

According to an embodiment, a method of measuring skin color may include converting a color of an image photographing skin into color data on a logarithmic coordinate system having a coordinate axis that corresponds to a primary color. Placing the data into a polygonal horn shape that encloses the data; Measuring a yellow group using a vertex position of the polygonal pyramid; And dividing the color data into a component in the illumination vector direction and a component in each of the dye vector directions to measure a plurality of pigment distributions.

Advantageous Effects

When using the ^' skin color measurement system and method according to an aspect of the present invention, the color vector generated by projecting the color of each pixel in the image of the skin to the RGB log coordinate system, the illumination vector and each pigment (pigment) The yellow, black and / or red color of the skin can be measured by separating it into components in the vector direction. In addition, the measurement result can be output as an image, so that the change in skin tone before and after using a specific cosmetic product can be clearly displayed.

[Brief Description of Drawings]

1 is a block diagram of a skin color measurement system according to an exemplary embodiment.

2 is a graph showing color data in which an image of a skin is projected onto an RGB log coordinate system.

3A to 3C are graphs showing color data obtained by using images of skins of different subjects, respectively.

4A to 4C are schematic diagrams illustrating output forms of red, black and yellow groups in a skin color measurement system according to an exemplary embodiment.

5 is a flowchart illustrating a method for measuring skin color according to an embodiment.

[Form for implementation of invention]

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. 1 is a block diagram of a skin color measurement system according to an exemplary embodiment.

Referring to FIG. 1, the skin color measurement system includes a transform module 20 and a low U measurement module. 30 and second measurement modules 40. In other embodiments the skin color measurement system may further include imaging modalities 10 and / or output mods 50. In the present specification, a unit, a module, or a system may refer to hardware, a combination of hardware and software, or software for implementing a specific function. For example, a part, module or system may refer to a running process, a processor, an object, an executable, a thread of execution, or a program. It may refer to both a specific application and a device for executing it.

The imaging modalities 10 are portions for photographing the subject's skin as an image. For example, the imaging module 10 may include a mobile device or a digital camera provided with a charge coupled device (CCD), and may generate an image by photographing a skin of a target subject. In one embodiment, the imaging module 10 may be configured as part of a skin color measurement system. However, in another embodiment, the skin color measurement system may not include the imaging modalities 10 and may receive only the color image by receiving the skin image of the target subject photographed using a separate device.

The conversion module 20 forms an RGB log formed by a coordinate axis that subtracts the color of each pixel of the photographed skin image to each primary color of red (R), green (G), and blue (B). This part generates color data by projecting onto a coordinate system. The skin color may be understood that light representing the primary color of the skin is darkened due to pigments such as melanin or hemoglobin. When the color expressed from the _skin is c _skin> c _base is the base color of the skin, the amount of melanin is m, and the amount of hemoglobin is h, the color c _skin is expressed by the following equation modelling

can be modeled.

[Equation 11

Cskin = Cbase · k | _igh t exp (— o _m m) · exp (-(j _h h)

In Equation 1 and o _h is the absorption coefficient of melanin and hemoglobin, respectively, k _light is a scalar value indicating the effect of the light contribution to the color expressed from the skin. If there is no pigment in the skin, the color developed on the skin is c _base . k _iight . When pigments such as melanin and / or hemoglobin are present on the skin, the light emitted from the skin is exponentially exponential from the primary color of the skin as the amount of pigment increases. Decreases.

On the other hand, taking the logarithm to both sides of the above equation 1 can be converted to a linear equation such as the following equation (2).

[Equation 2]

-log (c _skin ) =-log (cbase)-log (kiight) + o _m m + o _h h

As shown in Equation 2, the light expressed from the skin is -log ( _Cbase ) _reflected on the skin primary color, -log (k _light ) _{reflected on the} lighting effect, and _0ra m _reduced to light absorption by melanin. And it can be expressed as a linear sum of o _h h to the light absorption by hemoglobin.

Equations 1 and 2 described above may be independently applied to each of red 00, green (G), and blue (B). In other words, each term of Equation 2 may be represented by a three-dimensional vector having components that are respectively defined by red (R), green (G), and blue (B). In the present specification, this is referred to as an RGB vector. In addition, in the present specification, -log (c _base ) refers to a primary color vector.

-log (k _light ) refers to the lighting vector, o _m refers to the melanin vector, and Oh refers to the hemoglobin vector. That is, the color expressed from the skin may be expressed as a vector sum of a primary color vector, an illumination vector, and a plurality of pigment vectors (eg, melanin vector and hemoglobin vector).

In the skin color measurement system and method according to the embodiments described herein, the color expressed in each pixel of the skin image is converted into an RGB vector, and modeling based on Equations 1 and 2 described above from the RGB vector is performed. The primary color of each skin and the distribution of each pigment can be found. To this end, first, the conversion module 20 may convert the color of each pixel of the skin image into the color data by projecting the color of the pixel on the RGB log coordinate system. 2 is a graph showing the color data projected by the transform model 20 in the RGB log coordinate system.

Referring to FIGS. 1 and 2, the transform module 20 is formed by three coordinate axes that respectively define the color of each pixel of the skin image in three primary colors of red (R), green (G), and blue (B). Can be projected onto a logarithmic coordinate system. For example, the color of the i-th pixel in the skin image can be expressed as a three-dimensional vector of [C _iR , C _iG , C _iB ], and C _iR , C _iG , and C _iB are the red color of the i-th pixel, respectively. And green and blue components. The logarithm of each color value separated by RGB may be taken and converted into [log (C _iR ), log (C _iG ), log (C _iB )], which can be represented on the above-described RGB log coordinate system. For every pixel in the skin image, write the method described above. Can be used to obtain color data as shown in FIG.

Each point in the color data shown in FIG. 2 corresponds to the color of one pixel of the skin image projected in the RGB log coordinate system. In the figures appended here, the points on the RGB log coordinate system are shown on a gray scale, but this does not represent the actual color of the pixel that stands for each point. It will be readily understood by those skilled in the art that the pixel subtracted for each point has a color which is a combination of the red, green and blue components subtracted to the coordinates on the RGB log coordinate system of the point.

The first measurement modules 30 may calculate the yellow color of the skin by using the color data generated by the conversion modules 20. In one embodiment, the first measurement modules 30 may include a basic color calculator 310 and a yellow color calculator 320. The primary color calculator 310 may calculate the primary color vector of the skin from the color data. The primary color calculator 310 may arrange the illumination vector and the plurality of dye vectors having a predetermined direction in a polygonal pyramid shape that surrounds the color data projected by the conversion module 20 on the RGB log coordinate system.

The illumination vector refers to -log (k _llght ) in Equation 2 above. Assuming that white illumination is used that includes the RGB components uniformly, the direction of the illumination vector can be expressed as (1, 1, 1). However, this is merely an example, and the illumination vector may be configured to have a different direction in consideration of the characteristics of the light source and / or the white balance characteristic of the camera used for imaging the skin.

The plurality of pigment vectors may be, for example, melanin vectors and hemoglobin vectors, and refer to σ _π and o _h in Equation 2, respectively. The direction of the melanin vector and hemoglobin vector can be determined in advance using color data of a number of subjects. Methods of extracting melanin vector and hemoglobin vector from any image are well known to those skilled in the art, wherein melanin vector and hemoglobin to be used in embodiments of the present invention based on melanin vector and hemoglobin vector extracted from images of multiple subjects The direction of the vector can be determined.

For example, the orientation of the melanin vector and hemoglobin vector to be used in embodiments of the present invention may be determined based on the average of each of the melanin vector and hemoglobin vector extracted from skin images of multiple subjects. Alternatively, the melanin vector and the hemoglobin vector extracted from the skin images of a plurality of subjects, when placed in the form of triangular horns together with the above-described illumination vector, may be surrounded by specific melanin that may surround the color data of the plurality of subjects. It may also be selected in the direction of the vector and the hemoglobin vector.

In the present specification, the polygonal pyramid means a space surrounded by planes formed by two vectors of these vectors when the illumination vector and the plurality of pigment vectors are disposed at the same starting point. For example, when the plurality of pigment vectors are melanan vector and hemoglobin vector, the polygonal pyramid is the plane formed by the illumination vector and the melanin vector, the plane formed by the illumination vector and the hemoglobin vector, and the melanin vector and the hemo In globin vector, it refers to a triangular pyramid-shaped space surrounded by three planes of the plane formed.

In addition, in the present specification, enclosing color data by a polygonal pyramid (for example, a triangular pyramid) does not necessarily mean that all pixels of the color data are located inside the polygonal pyramid, and a certain percentage of all pixels of the color data is included. May refer to a configuration such that they are located inside the pyramid. For example, the polygonal pyramid may be arranged such that about 90% or more of the pixels are located inside the polygonal pyramid, which is illustrative and not limited to the above numerical value.

The primary color calculator 310 may arrange an illumination vector, a melanin vector, and a haemoglobin vector whose direction is predetermined in the form of a triangular pyramid surrounding color data of the target subject. Referring to FIG. 2, the orientations of the illuminated back melanin vector and the hemoglobin vector are shown as _log (k _light ), o _m and o _h , respectively. Can yield _l0 g _(Cbase) - Next, the primary color calculation unit 310 of the primary color vector of the basic color of the target subject skin using the position of the vertex of the triangular pyramid. At this time, _{-log (Cbase)} may be represented as a position relative to the origin of the coordinate system or a specific reference point.

On the other hand, the size and / or direction of the _base color vector -log (c _base ) may vary depending on the person. 3A to 3C are graphs showing color data obtained from images of skins of different testers, respectively. In each graph of FIGS. 3A to 3C, -log (c _base ) is a skin primary color vector of a corresponding subject, and the size and / or direction of the primary color vector is different for each subject. The primary color of the skin of each person is a phenomenon in which the overall skin tone is different, which is referred to herein as a yellow group.

The yellow color calculator 320 may measure the yellow color of the skin using the primary color vector calculated from the color data by the primary color calculator 310. First, the yellow color calculator 320 calculates a base color vector -log (c _base ) in the above-described lighting vector direction and excludes the same. It can be separated into the merging component. That is, the primary color vector separated into components in each direction may be expressed as Equation 3 below.

[Equation 3]

-log (Cbase) = 0C (1 ， 1 ， 1) + pVstbase + V

In Equation 3, α and β are scalar values, and γ is a vector value. (1, 1, 1) is a vector representing an illumination vector and v _stbase is a vector representing a standard skin color obtained from a plurality of subjects.

In one embodiment, the size of the remaining components other than α (1, 1, 1), which is a component of the illumination vector direction, among the primary color vectors -log (c _base ) separated into respective components as shown in Equation 3, that is, | 3v The absolute value of _stbase + γ can be defined as the yellow color of the skin. For example, assuming that the subject's skin color vector is (3, 4, 5), the remaining component is (0, 1) except for (3, 3, 3), which is the component of the illumination vector direction. , 2) is the yellow color of the subject's skin.

In another embodiment, the remaining components except for α (1, 1, 1), which is a component in the direction of the illumination vector, are separated into the components in the direction of the predetermined standard skin color vector from the -log (c _base ), which is the skin primary color vector can do. A standard skin color vector can be defined as a vector that is treated with the lightest of those based on skin primary color vectors measured from multiple subjects. The standard skin color vector is represented by v _stbase in Equation 3 above. According to this embodiment, of β Vstbase + Y, which is a component of the skin primary color vector except for the lighting vector direction, the absolute value of Y, except for 3v _stbase , which is a component of the standard skin color vector direction, is defined as a yellow group. do. For example, assuming that the skin color vector is (0, 1, 1) for the subject whose skin component is the (0, 1, 2) except for the component in the direction of the illumination vector, as described above, The absolute value of (0, 0, 1), which is the result of subtracting (0, 1, 1) from (0, 1, 2), becomes the yellow color of the subject's skin. The yellow group, defined as described in the above embodiments, represents the degree of the color expressed from the subject's skin deviating from the illumination vector, and expresses the overall skin tone except for the effect of the skin pigmentation of the subject as a single value. Therefore, by measuring the yellow color of the skin before and after the use of a particular cosmetic product, there is an advantage that can easily track the change in skin tone due to the use of the product. On the other hand, the second measurement modules 40 are projected by the transform modules 20 into the RGB log coordinate system. From the color data, the components of the melanin vector direction and the hemoglobin vector direction can be calculated. The direction of the melanin vector and hemoglobin vector can be previously determined using the color data of multiple subjects as described above. The components in the melanin vector direction and the components in the hemoglobin vector direction calculated as described above are respectively compared to the melanin distribution and the hemoglobin distribution of the skin of the subject. In addition, melanin distribution is expressed in the black phase of the skin, hemoglobin distribution is expressed in the red phase of the skin. That is, as the amount of melanin or hemoglobin in the skin increases, the black or red phase increases, respectively. In one embodiment, the skin color measurement system includes a melanin distribution (ie black) and a hemoglobin distribution (ie, yellow) produced by the first measurement modules 30 and the second measurement module 40. Output module 50 for displaying red color). For example, the output modules 50 may display the numerical values of the yellow, black and red phases of the skin at specific locations on the coordinate system that are subtracted from these values. In addition, the output modules 50 may display the skin image actually photographed at the specific position described above.

4A to 4C are schematic diagrams illustrating an output form by an output module in a skin color measurement system according to an exemplary embodiment.

Referring to FIG. 4A, the output modules may display numerical values measured from the skin of the target subject on a coordinate system formed by coordinate axes corresponding to yellow, black and red phases, respectively. In FIG. 4A, the coordinate axes of the yellow, black and red periods may be configured to show a range of 0¾ to 100% of the first measurement result when a plurality of measurements are performed. However, this is exemplary, and in other embodiments, each coordinate axis of the yellow, black and red phases may be configured to show, for example, a 90% to 110% range or other different range.

The output modules include a first image 520 corresponding to the yellow, black and red color values of the subject measured at a first time point (eg, before use of cosmetics), which is the first time of photographing, and a second time point (eg, a schedule). After using the period cosmetics), a second image 530 may be displayed which is measured by the yellow, black and red color values of the subject.

For simplicity, only the first and second images 520 and 530 are shown in FIG. 4A, but not only the positions where the first and second images 520 and 530 are located, but also the yellow and black portions of the positions in each other position in the coordinate system. And images corresponding to the red color value may be displayed. In addition, these other images may be generated by adjusting yellow, black and / or red in the photographed image of the actual subject.

First image 520 is located on plane 500 determined by the corresponding red phase value Similarly, the second image 530 is located on another plane 510 which is determined by the corresponding redness value. Compared to the first time point, the redness level of the subject was decreased at the second time point. As a result, it can be seen that the second plane 510 moved closer to the phosphorus direction than the first plane 500. .

4B is a schematic diagram illustrating only the first plane 500 in FIG. 4A, and FIG. 4C is a schematic diagram illustrating only the second plane 510 in FIG. 4A. 4B and 4C, since the first image 520 is the first photographed image, yellow and black values may correspond to 100%, respectively, so that the first image 520 may be displayed at the center on the first plane 500. On the other hand, the second image 530 may be displayed at a point shifted from the center of the crab plane 510 to the lower left on the crab 2 plane 510 since the yellow and black values are decreased compared to the crab 1 image 520, respectively.

For example, when the values of the red phase, the black phase, and the yellow phase of the target subject measured at the first time point are 100%, respectively, the red, black, and yellow phases of the subject subject measured at the second time point are 80%. Can be assumed to be%, 70% and 50%. In this case, the first image 520, which is the image of the target subject photographed at the first time point, is displayed at the position of (100, 100, 100) on the coordinate system, while the second image, which is the image of the target subject photographed at the second time point, is displayed. The image 530 may be output at the position (80, 70, 50) on the coordinate system.

Thus, by expressing the red, black and yellow color of the skin by using a three-dimensional image array (array), it is possible to visually display the skin condition clearly. In addition, if the first time point and the second time point are set before and after a certain period of use of a particular cosmetic product, respectively, the efficacy of the corresponding product is changed by changing the position from the crab 1 image 520 to the second image 530. You can see it visually. For example, the efficacy of the product can be represented by the length of the vector that connects the pixels from the particular pixel of the first image 520 to the pixels of the second image 530. Alternatively, the redness, yellowness, and blackness may be expressed in% to indicate the level of decrease in the numerical value, indicating the efficacy of the product.

The output forms of the yellow, black and red phases shown in FIGS. 4A-4C are merely exemplary, and the output modalities are the black color of the skin measured in the yellow and the second measured hairs measured in the first measurement hairs, and The red flag may also be output using other suitable display forms.

5 is a flowchart illustrating a method of measuring skin color according to an embodiment.

Referring to FIG. 5, first, a skin of a subject may be photographed as an image (S1). Next, color data may be generated by projecting the color of each pixel of the photographed skin image to the RGB log coordinate system (S2). RGB log coordinate systems are red (R), green (G), and blue (B) It may be a coordinate system formed by the coordinate axis of each of the three primary colors of, wherein each coordinate axis may be displayed in a log scale (log scale). Each pixel of the image is represented in the form of an RGB vector in the RGB log coordinate system.

Next, the illumination vector and the plurality of dye vectors whose directions are determined in advance can be arranged in a polygonal pyramid (for example, triangular pyramid) shape surrounding the projected color data (S3). The lighting vector is a vector for the effects of the lighting, and may be expressed as an RGB vector of (1, 1, 1) in the case of white lighting. The pigment vector can be a melanin vector and a hemoglobin vector. The direction of the melanin vector and hemoglobin vector can be determined in advance using color data obtained from skin images of a number of subjects.

Next, the primary color vector may be calculated using the vertex positions of the triangular pyramid consisting of the lighting vector, the melanin vector and the hemoglobin vector (S4). The primary color vector represents the skin's inherent overall skin tone, with the exception of the optical hop effect by the pigment in the subject's skin.

Next, a yellow group may be calculated using the primary color vector (S5). The yellow color can be obtained by dividing the primary color vector into the component of the illumination vector direction and the components of the other directions except this. In one embodiment, the yellow group may be defined as the size of the remaining components other than the components in the direction of the illumination vector in the primary color vector. Meanwhile, in another embodiment, the yellow group may be defined as the size of only the remaining components except the component of the predetermined standard skin color vector direction among the remaining components except the illumination vector direction in the primary color vector.

Meanwhile, the melanin vector component and the hemoglobin vector component can be calculated from the color data described above (S6). The components of the melanin vector and the components of the hemoglobin vector are subjected to the melanin distribution and the hemoglobin distribution of the subject subjects, respectively. In addition, the melanin distribution of the skin is expressed in the black phase of the skin, hemoglobin distribution of the skin may be expressed in the red phase of the skin.

Next, the red, black and yellow groups calculated by the above process can be output (S7). For example, in the coordinate system formed by the coordinate axes of the red, black and yellow phases, the skin image photographed at the position of the red, black and yellow phases of the target subject may be output. At this time, if the image before and after using a certain cosmetic product after displaying a certain period of time is displayed together, the change in the skin tone due to the use of the product can be visually confirmed by changing the position of the image before and after use. Skin color measurement method according to an embodiment in the present specification has been described with reference to the flow chart shown in the drawings. For simplicity, the method is shown and described as a series of blocks, but the invention is not limited to the order of the blocks, and some blocks may occur in different order or simultaneously with other blocks and as described and described herein. In addition, various other branches, flow paths, and blocks may be implemented in order to achieve the same or similar results. In addition, not all illustrated blocks may be required for the implementation of the methods described herein.

Although the present invention described above has been described with reference to the embodiments illustrated in the drawings, this is merely exemplary and will be understood by those skilled in the art that various modifications and variations of the embodiments are possible therefrom. . However, such modifications should be considered to be within the technical protection scope of the present invention. Therefore, the true technical protection scope of the present invention will be defined by the technical spirit of the appended claims.

Industrial Applicability

Embodiments relate to skin color measurement systems and methods.

Claims

[Range of request]

[Claim 1]

A conversion model for converting the color of the photographed image of the skin into color data on a logarithmic coordinate system having a coordinate axis that corresponds to the primary color;

First measurement modules for arranging a predetermined illumination vector and a plurality of pigment vectors in a polygonal pyramid shape surrounding the color data and measuring a yellow color using a vertex position of the polygonal pyramid; And

And a second measurement model for separating the color data into a component in the illumination vector direction and a component in the respective dye vector direction to measure a plurality of pigment distributions.

[Claim 2]

The method of claim 1,

The plurality of pigment vector is a skin color measurement system, characterized in that it comprises a melanin vector and hemoglobin vector.

[Claim 3]

The method of claim 1,

The first measurement module,

A basic color calculator configured to calculate a basic color vector from the color data to the vertex position of the polygonal pyramid; And

And a yellow color calculator calculating the yellow color by dividing the primary color vector into a component in the lighting vector direction and remaining components except for the components in the lighting vector direction. ^'

[Claim 4]

The method of claim 3,

The yellow color system is a skin color measurement system, characterized in that corresponding to the remaining components other than the components in the direction of the illumination vector in the primary color vector.

[Claim 5]

The method of claim 3 The yellow color calculator is configured to separate the remaining components excluding the components in the direction of the illumination vector from the primary color vector, into components other than the components of the preset standard skin color vector direction and the components of the standard skin color vector direction,

The yellow color is a skin color measurement system, characterized in that the remaining color except for the component of the standard skin color vector direction of the remaining components except the component of the illumination vector direction in the primary color vector.

[Claim 6]

The method of claim 1

And output outputs for displaying the yellow group calculated in the first measurement models and the plurality of pigment distributions calculated in the second measurement models on a coordinate system having coordinate axes that are respectively subtracted from the yellow group and the plurality of pigment distributions. Skin color measurement system.

[Claim 7]

The method of claim 6,

The output modules, the skin color measurement system, characterized in that for displaying the image of the skin photographed on the coordinate system having a left coordinate axis to each of the yellow group and the plurality of pigment distribution.

[Claim 8]

Converting the color of the image of the photographed skin into color data on a logarithmic coordinate system having a coordinate axis that corresponds to the primary color;

Arranging a preset illumination vector and a plurality of dye vectors in a polygonal shape surrounding the color data;

Measuring a yellow group using the vertex position of the polypyramid; And measuring the plurality of pigment distributions by separating the color data into components in the illumination vector direction and components in the respective dye vector directions.

[Claim 9]

The method of claim 8, The plurality of pigment vector is a skin color measurement method comprising a melanin vector and hemoglobin vector.

[Claim 10]

The method of claim 8,

Measuring the yellow color of the skin,

Calculating a primary color vector corresponding to the vertex position of the polygonal pyramid from the color data; and

And calculating the yellow color by separating the primary color vector into the components in the direction of the illumination vector and the remaining components except the components in the direction of the illumination vector.

[Claim 11]

The method of claim 10,

The yellow color is a method for measuring skin color, characterized in that the remaining color except for the component in the direction of the illumination vector in the primary color vector.

[Claim 12]

The method of claim 10,

The calculating of the yellow group may include separating the remaining components except for the components in the direction of the illumination vector from the primary color vector into remaining components except for the components of the preset standard skin color vector direction and the components of the standard skin color vector direction. Including,

The yellow color is a method for measuring skin color, characterized in that the remaining color except for the component in the direction of the standard skin color vector among the components except the component in the direction of the illumination vector in the primary color vector.

[Claim 13]

The method of claim 8,

And displaying the calculated yellow group and the plurality of pigment distributions on a coordinate system having a coordinate axis subtracted from each of the yellow group and the plurality of pigment distributions. [Claim 14]

The method of claim 13,

The displaying on the coordinate system having a coordinate axis that is respectively treated with the yellow group and the plurality of pigment distributions includes displaying an image of the skin photographed at a position that is calculated by the calculated yellow group and the plurality of pigment distributions. Characteristic method of measuring skin color.