Method and apparatus for measuring the moisture content of the lips

Abstract

To provide a method and device for effectively measuring the moisture content of the skin of a lip portion.SOLUTION: The method comprises a face image acquisition step S101 of acquiring a face image including the lip of a subject photographed in a near-infrared region; a measurement region extraction step S102 of extracting a specific measurement region of the lip of the subject from the face image acquired by the face image acquisition step S101; and a quantitation step S103 of quantitating the moisture content of the skin of the lip of the subject, on the basis of the mean value of signal intensities measured in the measurement region.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present invention relates to a method and apparatus for measuring the moisture content of lips using an image including the lips of a subject.

Background Art

[0002] In recent years, a technique has been disclosed for visualizing a moisturizing liquid applied to the face surface using two near-infrared spectroscopic images with a near-infrared camera in order to visualize moisture changes in the face (for example, Non-Patent Document 1). The technique shown in Non-Patent Document 1 measures the face using an InGaAs near-infrared camera (Sensors Unlimited, Inc. SU320M-1.7RT) having sensitivity up to a wavelength of 900 to 1700 nm, and converts the two acquired near-infrared spectroscopic images into a differential absorbance image, thereby realizing visualization of only the moisturizing liquid applied to the face.

[0003] In addition, a method for discriminating skin moisture content using near-infrared has also been disclosed (see, for example, Patent Document 1). The technique shown in Patent Document 1 includes a step of obtaining the reflection intensity at a plurality of points on the skin in the near-infrared wavelength range of 1050 to 1650 nm, and a step of substituting the reflection intensity obtained in the above step into a prediction formula showing the relationship between the skin moisture content prepared in advance and the reflection intensity in the near-infrared wavelength range to obtain the skin moisture content at a plurality of points, and discriminating the skin moisture content distribution from the obtained skin moisture content at a plurality of points. Further, Patent Documents 2 and 3 disclose techniques for acquiring a face image of a subject using a near-infrared camera and analyzing the skin of the subject from the acquired face image. Patent Documents 2 and 3 disclose that there is strong absorption of water at around 1460 nm and around 1920 nm in the region photographed by the near-infrared camera.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Patent Document 3

Non-Patent Document

[0005]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] On the other hand, the skin of the lip part is different from the skin of other parts in that the stratum corneum is thin, so it is likely to cause inflammation by various stimuli. Especially in winter when the humidity is low, it is likely to dry out. Therefore, it is important to be able to measure the moisture content of the skin of the lip. However, since the shape of the lip is complex, it is necessary to measure the moisture content separately from the skin of other parts, and so far, a method for specifically measuring the moisture content of the skin of the lip part has not been established. Also, so far, there has been no technology for visualizing the moisture content of the skin of the lip part.

[0007] Therefore, one of the objectives of the present invention is to provide a method and an apparatus capable of effectively measuring the moisture content of the skin of the lip part.

Means for Solving the Problems

[0008] The method of the present invention is a method for quantitatively measuring the moisture content of the skin of the lip of a subject, comprising: a face image acquisition step of acquiring a face image including the lip of the subject taken in the near-infrared region; a measurement region extraction step of extracting a specific measurement region of the lip of the subject from the face image acquired in the face image acquisition step; a quantification step of quantifying the moisture content of the skin of the lip of the subject based on the average value of the signal intensity measured in the measurement region. and

[0009] Furthermore, the device of the present invention is a measuring device for the moisture content of the skin of the lips, for use in the above-mentioned method of the present invention, including a near-infrared camera equipped with a lens having a specific transmission wavelength, focal length, and depth of field.

[0010] (Definition) In the present invention, the "central partial region" when the lower lip is divided into three parts refers to a region including a range of 10% before and after each value of the length in the left-right direction and the length in the up-down direction. For example, when the length in the left-right direction is 60 mm and the length in the up-down direction is 12 mm, the "central partial region" is a region in the range where the length in the left-right direction is 18 mm to 22 mm and the length in the up-down direction is 3.6 mm to 4.4 mm. [Advantages of the Invention]

[0011] According to the present invention, the moisture content of the skin of the lips can be effectively measured. [Brief Description of the Drawings]

[0012]

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Mode for Carrying Out the Invention

[0013] <Regarding the Present Invention> The present invention uses a face image of a subject with respect to the absorption characteristics of water near about 1460 nm and the strong absorption characteristics of water near about 1920 nm, which are captured using a near-infrared camera capable of capturing images in the wavelength range of 800 to 2500 nm. Note that the near-infrared light in the present invention specifically means a wavelength in the vicinity of about 800 to 2500 nm.

[0014] Based on the above, the present invention is specialized in extracting the lip part as a specific measurement region from the face images of the subject captured by the near-infrared camera, quantifying the amount of moisture using the extracted measurement region, and visualizing the quantified amount of moisture. The quantification of the amount of moisture is performed by measuring the signal intensity for the extracted measurement region (for example, based on its average value). Further, by stratifying into a plurality of stages based on the measured signal intensity and outputting in monochromatic colors of different colors or different densities for each stage, the distribution of the amount of moisture can be visualized.

[0015] Hereinafter, the present invention will be described in more detail with reference to the drawings.

[0016] <Photographing System: Schematic Configuration Example> First, a schematic configuration example of a face photographing device that photographs an image obtained in this embodiment will be described with reference to the drawings.

[0017] FIG. 1 is a diagram showing an example of the schematic configuration of the photographing system in this embodiment. The photographing system 10 shown in FIG. 1 is configured to include a face photographing device 11 and an image analysis device 12. The face photographing device 11 and the image analysis device 12 are connected by wire or wirelessly in a state where data and control signals can be transmitted and received via communication means such as a cable 13 and a wireless communication unit (not shown).

[0018] The face photographing device 11 sets the face of the subject to be analyzed, illuminates a predetermined part of the face with a predetermined light source irradiated inside the sphere, and acquires the image with a camera or the like. At this time, in this embodiment, face images of the subject photographed in a plurality of different near-infrared regions may be acquired. In that case, filtering may be performed by a preset band-pass filter to acquire image data in a predetermined near-infrared region.

[0019] Also, in this embodiment, when photographing the face image of the subject with the face photographing device 11, a color chart may be photographed together with the face image. Note that the color chart can be detachably attached to the face photographing device 11. That is, in this embodiment, the photographing is performed so that not only the face of the subject but also the color chart appears in the photographed image. Thereby, image correction can be performed using the color chart for the photographed image, so that the accuracy can be improved. Note that there may be one or a plurality of color charts. In the case of a plurality, for example, a color chart corresponding to the wavelength of the light source used at the time of photographing can be selected and used.

[0020] Also, the face photographing device 11 can reduce noise by installing a polarizing filter or the like on the lens of the camera to be photographed.

[0021] Specifically, the face photographing device 11 shown in FIG. 1 is configured to include a substantially spherical dome (housing) 21, at least one light source 22, a chin rest member 23, and a camera 24 as an imaging device on a base 20.

[0022] In FIG. 1, the dome 21 has a substantially spherical shape with a hollow inside. Also, the dome 21 has a shape such that, for example, a subject's face can fit inside. By making the shape of the dome 21 spherical in this way, the light irradiated from the internal light source can be diffused and the face of the subject can be efficiently irradiated with light uniformly (flatly).

[0023] Also, the light source 22 irradiates the inside of the dome 21 installed on the base 20 directly with light. Note that the number of light sources 22 only needs to be at least one (in the example of FIG. 1, two light sources 22-1 and 22-2 on the left and right of the face). Regarding the installation positions of the light sources 21-1 and 22-2, since they vary depending on the position of the shadow of the subject's face due to irradiation, etc., they can be adjusted as needed. It can be done.

[0024] Also, the light sources 22-1 and 22-2 are not particularly limited, and for example, incandescent lamps, halogen lamps, etc. as temperature irradiation light sources, high-pressure mercury lamps, self-ballasted mercury lamps, metal halide lamps, high-pressure sodium lamps, etc. as high-pressure discharge lamps (discharge emission light sources), fluorescent lamps, low-pressure sodium lamps, etc. as constant-pressure discharge lamps (discharge emission light sources), EL (Electroluminescence) lamps, LED (Light Emitting Diode) lamps, etc. as electroluminescence light sources can be used.

[0025] In particular, in this embodiment, for example, in order to capture an image in the near-infrared region, a halogen lamp or an LED lamp can be preferably used. These two light sources can each emit light in the same band, but there are differences due to the nature of their materials and the like. Specifically, the halogen lamp and the LED lamp have different ways of spreading light, and the LED lamp is more linear than the halogen lamp. Also, the LED lamp generates less heat than the halogen lamp. Therefore, which light source, the halogen lamp or the LED lamp, to use can be appropriately selected according to the object to be photographed, the purpose of photographing, the photographing environment, and the like. In this embodiment, since a light source is arranged near the face of the subject, it is more preferable to use an LED lamp from the viewpoint of less heat generation.

[0026] The chin-rest member 23 is a holding member for allowing the subject to enter the face into the inside of the dome 21 and holding and fixing it at a predetermined position. Also, the chin-rest member 23 is provided with a mechanism for adjusting the height and the left and right positions. For example, an image taken by a camera 24 or the like can be displayed on the display of the image analysis device 12, and it can also have a scale or the like that enables adjustment of the vertical and horizontal positions of the center of the camera 24 and the face. Further, the chin-rest member 23 may have a configuration or a moving mechanism that can obtain a side image or a hair image with the subject facing obliquely, horizontally, or backward instead of a front image of the subject.

[0027] The camera 24 acquires an image of the above-described predetermined near-infrared region. Specifically, a near-infrared camera (for example, manufactured by Sumitomo Electric Industries, Ltd.) that can acquire an image in a wavelength band of about 800 to 2500 nm can be used. Also, the lens attached to the camera 24 has a specific transmission wavelength, focal length, and depth of field, and for example, a 25 mm lens manufactured by Fujifilm Corporation can be used. In this embodiment, a polarizing filter may be provided in order to eliminate noise such as surface reflection of the face image of the subject to be photographed and suppress the glare on the surface to obtain a clear image. Specific examples of the polarizing filter will be described later.

[0028] In this embodiment, in order to acquire an image in a predetermined near-infrared region, for example, a band-pass filter may be installed in front of the light source or in front of the lens to acquire an image in the predetermined near-infrared region. Further, in this embodiment, in order to capture images from a plurality of different near-infrared regions, for example, a mechanism may be provided that allows the filter to be slid and automatically switched, or the user may move the slide to switch the filter for each capture. Here, FIG. 2 is a diagram for explaining the installation position of the filter.

[0029] Further, the above-described band-pass filter may include first filters 31-1 and 31-2 disposed between the light sources 22-1 and 22-2 and the subject, and a second filter 32 and a third filter 33 disposed between the subject and the camera (lens). Here, for the first filter 31, for example, a UVA cut or an infrared attenuation filter can be used, and for example, GG395 manufactured by SCHOTT (for example, thickness 3 mm, length 100 × width 100 mm) can be used.

[0030] Furthermore, the second filter 32 may be an ND filter that is used in combination with, for example, a band-pass filter (third filter 33) described later. The ND filter is a filter for adjusting the amount of light entering the lens, and is for adjusting different amounts of light depending on the type of band-pass filter.

[0031] In this embodiment, a plurality of band-pass filters are used to acquire an image in a predetermined near-infrared region. Since the amount of transmitted light varies depending on the wavelength, it is preferable that the measurement can be performed without changing the camera settings such as the adjustment of the lens as much as possible. Therefore, by preparing a plurality of the above-described ND filters corresponding to the plurality of band-pass filters and appropriately switching and using them, attenuation of the light amount and the like can be performed to adjust the light amount. As the ND filter, for example, NG5 manufactured by SCHOTT (for example, a circle with a diameter of 25.4 mm and a thickness of 1 mm) can be used.

[0032] Here, as the third filter 37 for acquiring an image in a predetermined near-infrared band using a plurality of band-pass filters, for example, a filter manufactured by Spectrogon can be used. Also, the region of the third filter 37 can acquire an image obtained from a band of, for example, about 1100 to 1360 nm when acquiring a base image, and can acquire an image with a center wavelength of about 1300 nm ± 40 nm, for example.

[0033] Also, when acquiring an image with strong water absorption characteristics, for example, an image obtained from a band of about 1350 to 1640 nm can be acquired, and preferably an image with a center wavelength of about 1460 nm ± 45 nm can be acquired. Similarly, when acquiring an image with strong water absorption characteristics and better sensitivity, for example, an image obtained from a band of about 1860 to 2200 nm can be acquired, and preferably an image with a center wavelength of about 1920 nm ± 55 nm and about 1950 nm ± 56 nm can be acquired.

[0034] Note that the filter used to acquire these near-infrared band images may be realized by a single filter or may be a combination of a plurality of filters.

[0035] Furthermore, in this embodiment, for example, a color chart may be installed on the jaw mounting member 23 shown in FIG. 2 facing the camera 24 side. Thereby, the captured image by the camera 24 can include the face image of the subject and the color chart, and correction between a plurality of images can be performed using the color chart to improve the accuracy. Specific examples of the color chart will be described later.

[0036] The face image of the subject captured by the camera 24 using the lighting device 11 with the above-described configuration etc. is output to the image analysis device 12 via the cable 13 etc. shown in FIG. 1. Note that the communication between the face photographing device 11 and the image analysis device 12 may be wireless communication using, for example, infrared rays or the like, or may be wired communication via a LAN cable or the like. Furthermore, the captured image may be transmitted to the image analysis device 12 located remotely using a communication network such as the Internet.

[0037] Here, in this embodiment, the image captured by the face imaging device 11 does not have to be the entire face of the subject, and any region including a specific measurement region of the lips described later is sufficient. Further, the image captured by the face imaging device 11 may be an image captured according to an operator's instruction, or may be a real-time video captured continuously.

[0038] The image analysis device 12 acquires an image in a predetermined near-infrared region captured by the face imaging device 11, extracts a specific predetermined region of the lips based on the acquired image, and performs analysis related to moisture using the signal intensity measured in the measurement region. Thereby, the moisture content of the skin of the lips can be quantified and used as an index of the lip state. Furthermore, by visualizing and outputting the moisture content of the skin of the lips, highly accurate analysis, evaluation, or display of the results can be performed. Note that the image analysis device 12 can realize the analysis processing in this embodiment using a general-purpose personal computer or the like.

[0039] <Regarding the polarizing filter> Next, a specific example of the polarizing filter in the above-described embodiment will be described. Usually, in image capture, unnecessary reflected light (such as glare) may occur on the surface of the observation object due to the light source, which is unnecessary for analysis. Further, the unnecessary reflected light affects the luminance value of the acquired image, and there is a possibility that an error may occur when performing quantitative evaluation by image analysis, which becomes a problem.

[0040] Therefore, in this embodiment, a polarizing filter is installed in front of, behind, or both in front and behind the lens of the camera 24. Further, in this embodiment, a polarizing filter may be installed in front of the light source instead of near the lens. Furthermore, in this embodiment, polarizing filters are installed on both the lens and the light source. Note that one or a plurality of polarizing filters can be installed.

[0041] Thereby, in this embodiment, unnecessary reflected light generated on the surface of the observation object can be removed. Further, in this embodiment, the installation of these filters reduces noise and enables highly accurate analysis.

[0042] <Regarding Color Charts> Next, a specific example of the color chart in the above-described present embodiment will be described. Usually, when performing comparison between images using quantitative evaluation by image analysis, slight differences due to shooting conditions become an analytical problem. Therefore, in the present embodiment, by correcting the luminance value of the acquired image using an arbitrary color chart whose reflectance from white to black can be specified, comparison between images becomes possible regardless of the timing of image acquisition, and accurate analysis can be performed.

[0043] Note that, as an example, a plurality of color charts with different reflectances are arranged in parallel on a board, and the color chart can be selected according to the wavelength of the light source used when photographing the subject. By using the color chart in this way, the luminance between the photographed images can be corrected.

[0044] <Image Analysis Apparatus 12: Example of Functional Configuration> Next, an example of the functional configuration of the image analysis apparatus 12 in the present embodiment will be described with reference to the drawings. FIG. 3 is a diagram showing an example of the functional configuration of the image analysis apparatus in the present embodiment. The image analysis apparatus 12 shown in FIG. 3 is configured to include an input means 41, an output means 42, a storage means 43, a photographed image acquisition means 44, an image analysis means 45, an evaluation means 46, an image generation means 47, and a control means 48.

[0045] The input means 41 receives inputs such as the start / end of various instructions such as an image acquisition instruction, an image analysis instruction, and an evaluation instruction from an operator. Note that the input means 41 includes, for example, a keyboard, a pointing device such as a mouse, and the like. Further, the input means 11 also has a function of inputting an image including an imaging portion of a subject photographed by an imaging means such as a digital camera.

[0046] The output means 42 performs display and output of the content input by the input means 41, the content executed based on the content, and the like. Note that the output means 42 can include a display device such as a display and / or a sound output device such as a speaker. Further, the output means 42 may include a printing device such as a printer. In this case, the image analysis result and the like can be printed on a printing medium such as paper and provided to an operator, a subject, or the like.

[0047] Note that the input means 41 and the output means 42 may be an integrated input / output means such as a touch panel that combines, for example, a touch screen as the input means 41 and a display as the output means 42. In this case, input can be performed by touching a predetermined position using an operator's finger, a pen-type input device, or the like.

[0048] The storage means 43 stores various data such as each image information, such as the captured image obtained by the captured image acquisition means 44, the image analysis result by the image analysis means 45, and the evaluation result generated by the image generation means 47. Further, the storage means 43 can read out the various stored data as needed.

[0049] The captured image acquisition means 44 acquires a face image of a subject captured by the camera 24 in the face imaging device 11. Note that when the captured image acquisition means 44 captures the face of the subject by the face imaging device 11, the type, position, number, etc. of the light source to be used can be set according to the content of the image to be captured. Further, the captured image acquisition means 44 generates instruction information indicating the imaging conditions in order to acquire an image of a predetermined near-infrared region filtered by a predetermined band-pass filter by using the above-described first to third filters 31 to 33 in combination with the camera 24 of the face imaging device 11, and outputs the instruction information to the face imaging device 11. Note that the image acquired by the captured image acquisition means 44 is stored in the storage means 43.

[0050] The image analysis means 45 acquires a face image from the photographed image acquisition means 44, extracts a specific measurement area of the lips from the acquired face image, and measures the signal intensity in the extracted measurement area.

[0051] The image analyzed by the image analysis means 45 may be an image captured from the face photographing device 11 or an image previously stored in the storage means 43. When the image analyzed by the image analysis means 45 is an image captured from the face photographing device 11, the image analysis means 45 may analyze the image in real time each time.

[0052] The evaluation means 46 quantifies the moisture content of the skin of the lips based on the average value of the measured signal intensities.

[0053] The image generation means 47 generates an image for presenting to the user based on the result analyzed by the image analysis means 45 and the result evaluated by the evaluation means 46. Specifically, the lip part of the acquired face image is stratified into a plurality of stages based on the measured signal intensity, and an image is generated in which each stage is represented by a different color or a monochromatic color with a different density.

[0054] The control means 48 controls the entire configuration of each component of the image analysis device 12. Specifically, the control means 48 performs each control such as image analysis processing and image generation processing based on an instruction from the input means 41 by an operator or the like.

[0055] <Image analysis device 12: Hardware configuration> Here, in the above-described image analysis device 12, an execution program (image analysis program) that enables each function to be executed by a computer is generated, and for example, by installing the execution program in a general-purpose personal computer, a server, etc., it is possible to perform analysis using an image in a predetermined near-infrared region that has been photographed.

[0056] Here, an example of the hardware configuration of a computer capable of realizing the image analysis processing in this embodiment will be described with reference to the drawings.

[0057] FIG. 4 is a diagram showing an example of a hardware configuration capable of realizing the image analysis process in this embodiment. The computer main body in FIG. 4 is configured to include an input device 51, an output device 52, a drive device 53, an auxiliary storage device 54, a memory device 55, a CPU (Central Processing Unit) 56 that performs various controls, and a network connection device 57, and these are interconnected by a system bus B.

[0058] The input device 51 has a pointing device such as a keyboard and a mouse operated by a user or the like, and inputs various operation signals such as execution of a program from the user or the like. Further, the input device 51 can also input various data such as a face image of a subject photographed in the near-infrared region obtained via a communication network from an external device connected to the network connection device 57 or the like.

[0059] The output device 52 has a display for displaying various windows, data, etc. necessary for operating the computer main body for performing the process in the present invention, and can display the progress and results of program execution by a control program of the CPU 56. Further, the output device 52 can print the above-described processing results, etc. on a printing medium such as paper and present them to a user or the like.

[0060] Here, the execution program installed in the computer main body in the present invention is provided by a recording medium 58 such as a USB (Universal Serial Bus) memory, a CD-ROM, a DVD, or the like. The recording medium 58 on which the program is recorded can be set in the drive device 53, and the execution program included in the recording medium 58 is installed from the recording medium 58 via the drive device 53 in the auxiliary storage device 54.

[0061] The auxiliary storage device 54 is a storage means such as a hard disk, and can store the execution program in the present invention, a control program provided in the computer, etc. and perform input / output as necessary.

[0062] The memory device 55 stores the execution program and the like read from the auxiliary storage device 54 by the CPU 56. Note that the memory device 55 includes a ROM (Read Only Memory), a RAM (Random Access Memory), and the like.

[0063] Also, all or part of the execution program may be downloaded from an external device as needed via an arbitrary network. Further, the auxiliary storage device 54 in which the execution program is installed and / or the memory device 55 that stores the installed execution program may be provided in the external device. The external device may be a server. The server may be a specific server or an indefinite server such as a cloud infrastructure. Furthermore, the execution program may be provided by a subscription-based service. A subscription-based service is one of the usage forms of computer software, and is a service in which a fee is paid according to the period during which the software is used. Thus, the usage form of the execution program may be arbitrary and is not limited.

[0064] Based on a control program such as an OS (Operating System) and the execution program stored in the memory device 55, the CPU 56 can control the processing of the entire computer, such as various operations and data input / output with each hardware component, to realize each process. Note that various information and the like required during the execution of the program can be acquired from the auxiliary storage device 54, and the execution results and the like can also be stored.

[0065] By connecting to a communication network or the like, the network connection device 57 can acquire an execution program from another terminal or the like connected to the communication network, or provide the execution result obtained by executing the program or the execution program itself in the present invention to another terminal or the like.

[0066] With the hardware configuration as described above, the image analysis processing in the present invention can be executed. Also, by installing a program, the image analysis processing in the present invention can be easily realized on a general-purpose personal computer or the like.

[0067] <Image analysis processing procedure> Next, the image analysis processing procedure in the present embodiment using the above-described image analysis apparatus 12 and image analysis program will be described. FIG. 5 is a flowchart showing an example of the image analysis processing procedure in the present embodiment.

[0068] In the image analysis processing shown in FIG. 5, first, a face image including the lips of a subject taken in the near-infrared region is acquired (face image acquisition step: S101). The face image may be acquired by directly capturing face image data captured by a camera from the camera, or by capturing face image data stored in the storage means from the storage means. Also, the face image does not need to be the entire face as long as it includes the lips of the subject.

[0069] Next, a specific measurement region of the lips of the subject is extracted from the face image acquired in the face image acquisition step (S101) (measurement region extraction step: S102). In the extraction of the measurement region, first, the lip portion is specified from the face image of the subject, and further, a specific measurement region is extracted from the specified lip portion. Any image processing technique can be used to specify the lip portion. Also, as shown in FIG. 6, the specific measurement region can be the central portion region (the region shown in white in the figure) when the lower lip is divided into three equal parts in the left-right direction and the upper-lower direction based on the length between both ends in the left-right direction and the length between the upper and lower ends of the specified lip portion. Also, the specific measurement region may be a further partial region within the central portion region (for example, a similar region with an area reduced by 50 to 90%).

[0070] Next, the signal intensity is measured in the measurement area extracted in the measurement area extraction step (S102), and based on the average value of the measured signal intensity, the moisture content of the skin of the subject's lips is quantified (quantification step: S103). The quantified moisture content can be used as an index representing the state of the subject's lips, such as by being displayed on a display means.

[0071] The quantified moisture content can be visualized (visualization step: S104). The visualization of the moisture content can be performed, for example, by stratifying the lip portion of the face image acquired in the face image acquisition step (S101) into a plurality of stages based on the measured signal intensity and outputting it in different colors or monochromes with different densities for each stage. Thereby, the moisture content of the skin of the lips can be visually recognized. The number of stages for stratification may be arbitrary, and for example, it can be preferably 3 or more stages, more preferably 4 or more stages, and still more preferably 5 or more stages. Also, if the number of stages is too large, the visualization process becomes complicated and it becomes difficult to visually distinguish each stage by color or density. Therefore, it can be preferably 10 or less stages, more preferably 8 or less stages, and still more preferably 6 or less stages. In the stratified stage, it may be a gradation in which the lightness or chroma, or both the lightness and chroma, continuously changes from a certain value to a certain value.

[0072] Also, as another example of the visualization of the moisture content, it can also be performed by outputting a graph representing the relationship between the period and the moisture content of the moisture content quantified from a plurality of face images taken at intervals (for example, one week) for the same subject. For example, assume that the moisture content of the skin of the lips quantified through the above series of steps from a face image of an arbitrary subject one week ago is stored in the storage means, and now a current face image of the same subject is newly acquired and the moisture content of the skin of the lips is similarly quantified. In this case, the moisture content one week ago for the same subject is taken in from the storage means and plotted on a graph with the period on the horizontal axis and the moisture content on the vertical axis together with the current moisture content. By doing so, the temporal change in the moisture content of the skin of the lips can be visually grasped.

[0073] The visualization step S104 described above may be optional.

[0074] <Measurement Example of Moisture Content> Next, the results of examining the measurement of the moisture content of the lips according to this embodiment will be described.

[0075] <Examination 1> In Examination 1, the moisture content of the lips every week when the external preparation for lips was continuously used for 2 weeks was quantified from the face images of 19 subjects photographed with a camera. The external preparation for use was applied for 8 to 12 hours per day, and the photography was performed in a state where the external preparation for lips was removed by washing the face and removing makeup. As shown in FIG. 6, the quantification region was the central partial region (the region shown in white in the figure) when the lower lip was divided into three equal parts in both the left-right direction and the upper-lower direction based on the length between both ends in the left-right direction and the length between the upper and lower ends of the specified lip portion. The acquisition of the subjects' face images was performed in a "control wavelength region" that is hardly absorbed by water, a "first wavelength region" that exhibits strong absorption characteristics by water, and a "second wavelength region" that exhibits strong absorption characteristics by water. The "control wavelength region" is a wavelength region of 1300 nm ± 40 nm, and the specific wavelength in Examination 1 was 1300 nm. The "first wavelength region" is a wavelength region of 1500 ± 45 nm, and the specific wavelength in Examination 1 was 1462 nm. The "second wavelength region" is a wavelength region of 1920 nm ± 55 nm, and the specific wavelength in Examination 1 was 1950 nm.

[0076] The quantification results of the moisture content are shown in FIGS. 7A to 7C. FIG. 7A shows the quantification results in the control wavelength region, FIG. 7B shows the quantification results in the first wavelength region, and FIG. 7C shows the quantification results in the second wavelength region. Each is a graph where the horizontal axis is the continuous use period and the vertical axis is the average value of the measured signal intensity. In the first wavelength region and the second wavelength region, the more moisture there is, the more light is absorbed, so the measured signal intensity becomes lower. Therefore, in order to intuitively show the amount of moisture, the scale of the vertical axis is arranged so that the signal intensity decreases as it goes upward in each graph.

[0077] From the graphs of FIGS. 7A to 7C, the following can be understood. The amount of moisture has increased significantly after 1 week (1W) and 2 weeks (2W) compared to before the start of continuous use (0W).

[0078] <Study 2> In conjunction with Study 1, the moisture content of the lips was measured using a corneometer (manufactured by Courage + Khazaka, model number: Corneometer CM825), which is commonly used to measure the moisture content. That is, in Study 1, in addition to photographing with a camera, the moisture content was also measured using a corneometer. The results are shown in FIG. 8. From FIG. 8, it can be seen that even when measured with a corneometer, the amount of moisture has increased significantly due to the continuous use of the external preparation for the lips.

[0079] <Study 3> In Study 3, the lip portion of the face image obtained in Study 1 was stratified into multiple levels based on the measured signal intensity and output in monochrome with different concentrations for each level, thereby visualizing the moisture content. The results of the visualization are shown in FIG. 9. In FIG. 9, for easy comparison, the images before the start of continuous use (0W), 1 week after the start of continuous use (1W), and 2 weeks after the start of continuous use (2W) are shown side by side. From FIG. 9, it can be seen that the moisture content of the lips has improved due to continuous use. In FIG. 9, the levels of the moisture content are output in monochrome with different concentrations, but they may also be output in different colors, for example, in order from less moisture content, red, orange, yellow, and blue.

[0080] <Study 4> In Study 4, the subjects were asked a questionnaire about the condition of their lips when using the external preparation for the lips, and the results were compared with the results obtained in Study 1 and Study 2.

[0081] The results of the questionnaire are shown in FIG. 10A. The results obtained in Study 1 are shown in FIG. 10B, and the results obtained in Study 2 are shown in FIG. 10C. In the questionnaire, the subjects were asked to evaluate three items regarding the condition of their lips, namely, "whether moisture can be felt on the lips", "whether the lips are not dry", and "whether the lips are plump", on a 6-point scale from 0 to 5.

[0082] From the graph of FIG. 10A, it can be seen that all items have improved one week (1W) after the start of continuous use. Also, when comparing FIGS. 10A, 10B, and 10C, surprisingly, the result of quantification using the face image taken in the near-infrared region is closer to the feeling actually felt by the subject compared to the result measured using a corneometer. That is, it can be seen that the moisture content can be quantified more accurately by quantifying the moisture content using the face image taken in the near-infrared region. The reason for this is presumably that the method using the face image taken in the near-infrared region can quantify the moisture content non-contact, so it worked effectively for quantifying the moisture content of the lips with a complex shape compared to the contact-type measurement method such as a corneometer.

[0083] As described above, the present invention has been described in detail. However, the present invention is not limited to the above-described embodiments, and various modifications and changes are possible within the scope of the gist of the present invention described in the claims.

Explanation of Reference Numerals

[0084] 10 Imaging system 11 Face imaging device 12 Image analysis device 22 Light source 24 Camera 41 Input means 42 Output means 43 Storage means 44 Imaging image acquisition means 45 Image analysis means 46 Evaluation means 47 Image generation means 48 Control means 51 Input device 52 Output device

Claims

1. A method for measuring the moisture content of the skin of a subject's lip, comprising: a face image acquisition step of acquiring a face image including the lip of the subject, the face image being taken in the near-infrared region of 1350 nm to 1640 nm; a measurement region extraction step of extracting a specific measurement region of the lip of the subject from the face image acquired in the face image acquisition step; a quantification step of quantifying the moisture content of the skin of the lip of the subject based on the signal intensity measured in the measurement region and including a method.

2. The method according to claim 1, characterized in that the specific measurement region of the lip is a central partial region when the lower lip is divided into three equal parts in both the left-right direction and the upper-lower direction based on the length between both ends in the left-right direction and the length between the upper and lower ends of the lower lip.

3. The face image acquisition step includes taking a face image including the lip of the subject by a near-infrared camera having a lens with a specific transmission wavelength, focal length, and depth of field The method according to claim 1 or 2, characterized by including.

4. The method according to any one of claims 1 to 3, further including a visualization step of stratifying the lip portion of the face image acquired in the face image acquisition step into a plurality of stages based on the measured signal intensity and outputting it in monochrome with different colors or different densities for each stage.

5. A photographing system for quantifying the moisture content of the skin of the lip, including a face photographing device including a near-infrared camera having a lens, an accumulating means, an input means, an output means, an image analysis means, and an image analysis device, acquiring an image in the near-infrared region obtained from a band of 1350 to 1640 nm by the face photographing device; inputting the acquired image from the input means of the image analysis device; the image analysis device extracting a specific measurement region of the lip from the input image; the image analysis device measuring the signal intensity of the extracted measurement region; the image analysis means quantifying the moisture content from the signal intensity; and outputting the quantified moisture content to the output means and including the photographing system.

Images