Method and device for determining UV coverage rate after applying real-life stress

Abstract

To provide a method for determining UV coverage of a UV protective formulation.SOLUTION: A method of determining a UV coverage of a UV protective formulation by a measurement process comprises the steps of: obtaining an image of a target by irradiating the target with light before applying the UV protective formulation onto the target; obtaining an image of the target by irradiating the target with light after applying the UV protective formulation onto the target; obtaining an image of the target by irradiating the target with light after applying stress to the target onto which the UV protective formulation is applied; setting at least one region of interest on the target in the image obtained in each image obtaining step; obtaining intensity of detected light in the regions of interest in the images obtained from the image obtaining steps; and determining a UV coverage of the UV protective formulation by comparing the intensity of the detected light in the regions of interest in the images obtained from the image obtaining steps.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a method and a device for determining the UV coverage rate after applying real-life stress.

Background Art

[0002] Protecting a target such as human skin from ultraviolet light (UV protection) is important for skin health and beauty. After applying a formulation having a UV protection effect, i.e., after a sunscreen is applied onto the target, the sunscreen is ultimately removed by stress on the sunscreen such as wetting the target, wiping the target with a towel, or the passage of time. Therefore, the effect of the sunscreen is ultimately lost due to stress and the passage of time. In order to effectively protect the target, it is necessary to measure the current protection effect. However, since ultraviolet light is invisible to the human eye, the UV protection effect cannot be seen either. Therefore, consumers cannot visually inspect the degree to which the UV protection effect is maintained.

[0003] When a target is irradiated with UV light, fluorescent substances such as collagen, NADPH, and amino acids contained in the target emit fluorescence, for example, in the visible range. The amount of UV light reaching the irradiated target, in other words, the UV protection effect of the sunscreen applied onto the irradiated target, can be determined by measuring the amount of fluorescence.

[0004] FIG. 10 shows a conventional method for determining the intensity of fluorescence emitted from a target in response to irradiation with UV light. In this method, light 1016 containing UV light is irradiated onto a target 1010. The target 1010 emits fluorescence 1020 in response to irradiation with the light 1016. When the fluorescence 1020 is incident on a light sensor 1006, the light sensor 1006 outputs a signal according to the intensity of the fluorescence 1020. The change in the intensity of the fluorescence is calculated by the following formula.

[0005]

Equation

[0006] In the above formula, T imm represents the intensity of fluorescence measured immediately after applying the UV protection preparation onto the target, and T i represents the intensity of fluorescence measured after applying a predetermined number of stresses to the UV protection preparation.

[0007] However, with this conventional method, only a part of the target can be measured at a time. For example, when the target is a human face, it is difficult to simultaneously evaluate the UV protection effect in a plurality of parts of the face such as the forehead and the left and right cheeks, and to evaluate the distribution of the UV protection effect.

[0008] An imaging system has been developed that can obtain a standard image of a human face as a target under certain irradiation conditions. For example, the Visia system of Canfield Scientific, Inc. is commercially available. The UV imaging function of such an imaging system is often used to estimate and show pigmentation points that significantly absorb UV light. Furthermore, the UV imaging function is often used as an example to show the effect of a UV protection preparation. However, to the knowledge of the inventors, such an imaging system is not used to directly quantify the temporal change in the distribution of the UV protection preparation on the surface of the skin. In Non-Patent Document 1, it was reported that a blue fluorescent pigment was used to estimate the resistance of some types of UV protection preparations to water.

[0009] Another system developed by L’Oreal, for example, the UV patch, aims to obtain real-time data and changes in the UV protection level based on a photosensitive patch that occurs in response to UV irradiation. The UV patch has the advantage of being portable, but the purpose of the UV patch is not to evaluate the distribution of the applied UV protection preparation. Furthermore, with the UV patch, it is necessary to intentionally irradiate with UV light, in other words, the UV patch does not react unless exposed to sunlight.

Prior Art Documents

Non-Patent Literature

[0010]

Non-Patent Literature 1

Summary of the Invention

Problems to be Solved by the Invention

[0011] An object of the present invention is to quantify the change and uniformity of the spatial distribution of a UV protection preparation with respect to the first uniform application of a sufficient amount of the UV protection preparation, called "UV coverage". It should be noted that the object of the present invention is not to estimate the sun protection factor SPF of the UV protection preparation applied on the surface of the skin.

Means for Solving the Problems

[0012] A method for determining the UV coverage of a UV protection preparation by a measurement process according to an embodiment of the present invention is as follows: acquiring an image of the target by irradiating the target with light before applying the UV protection preparation on the target; acquiring an image of the target by irradiating the target with light after applying the UV protection preparation on the target; acquiring an image of the target by irradiating the target with light after applying stress to the target coated with the UV protection preparation; setting at least one region of interest on the target in the image acquired in each image acquisition step; acquiring the intensity of the detected light in the region of interest in the image acquired from the image acquisition step; A step of determining the UV coverage of the UV protection preparation by comparing the intensities of the detected light in the region of interest in the image obtained from the image acquisition step.

[0013] In one embodiment of the present invention, the step of obtaining an image of the target by irradiating the target with light after applying stress to the target coated with the UV protection preparation may be performed once or multiple times.

[0014] In one embodiment of the present invention, the step of determining the UV coverage of the UV protection preparation may determine the UV coverage of the UV protection preparation based on the following formula.

[0015]

Equation

[0016] In the above formula, T0 represents the intensity of the detected light obtained from the image of the target before applying the UV protection preparation, and T imm represents the intensity of the detected light obtained from the image of the target after applying the UV protection preparation onto the target, and T i represents the intensity of the detected light obtained from the image of the target after applying the i-th stress to the target coated with the UV protection preparation, and i represents an integer of 1 or more.

[0017] In one embodiment of the present invention, the step of obtaining an image of the target may include a step of obtaining an image of the fluorescence emitted from the target in response to irradiating the target with light.

[0018] In one embodiment of the present invention, the step of obtaining an image of the target may include a step of attenuating or blocking fluorescence having a wavelength outside the range between 290 nm and 420 nm by filtering.

[0019] In one embodiment of the present invention, the target may be a human face or a dummy sample containing a fluorescent substance similar to the fluorescent substance contained in human skin.

[0020] In one embodiment of the present invention, the step of setting at least one region of interest may include the step of setting a plurality of regions of interest on a human face, and the step of determining the UV coverage may include the step of simultaneously determining the UV coverage in the plurality of regions of interest.

[0021] In one embodiment of the present invention, the light for irradiating the target may have a wavelength in the ultraviolet range.

[0022] A device for determining the UV coverage of a UV protection preparation according to one embodiment of the present invention is a light source for irradiating the target with light, a detector for acquiring an image of the target in response to irradiating the target with light, and a controller for determining the UV coverage of the UV protection preparation applied on the target based on the image of the target acquired by the detector, wherein the controller is configured to set at least one region of interest on the target in the image, and the controller is configured to determine the UV coverage of the UV protection preparation by comparing the intensities of the detected light in the regions of interest in the image of the target before applying the UV protection preparation on the target, the image of the target after applying the UV protection preparation on the target, and the image of the target after applying stress to the target coated with the UV protection preparation.

[0023] In one embodiment of the present invention, the image of the target after applying stress to the target coated with the UV protection preparation may be acquired one or more times.

[0024] In one embodiment of the present invention, the controller may be configured to determine the UV coverage of the UV protection preparation based on the following formula.

[0025] [Number]

[0026] In the above formula, T0 represents the detected light intensity obtained from the image of the target before applying the UV protection preparation onto the target, T imm represents the detected light intensity obtained from the image of the target after applying the UV protection preparation onto the target, and T i represents the detected light intensity obtained from the image of the target after applying the i-th stress to the target coated with the UV protection preparation, where i represents an integer of 1 or more.

[0027] In one embodiment of the present invention, the detector may be configured to acquire an image of fluorescence emitted from the target in response to irradiating the target with light.

[0028] In one embodiment of the present invention, the detector may include a filter configured to attenuate or block fluorescence having a wavelength outside the range between 420 nm and 520 nm by filtering.

[0029] In one embodiment of the present invention, the target may be a human face or a dummy sample containing a fluorescent substance similar to the fluorescent substance contained in human skin.

[0030] In one embodiment of the present invention, at least one region of interest may be a plurality of regions of interest on a human face, and the controller may be configured to simultaneously determine the UV coverage in the plurality of regions of interest.

[0031] In one embodiment of the present invention, the light source may be configured to irradiate the target with light having a wavelength in the ultraviolet light range. [Advantages of the Invention]

[0032] According to the present invention, there are provided a method and a device for determining the UV coverage of a UV protection preparation.

Brief Description of the Drawings

[0033]

Figure 1

Figure 2

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Figure 3B

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Figure 10

DETAILED DESCRIPTION OF THE INVENTION

[0034] A device 1 for determining the ultraviolet light coverage (UV coverage) according to some embodiments of the present invention, as shown in FIG. 1, includes a light source 2 for irradiating a target 10 with light 16, a detector 6 for acquiring an image of the target 10 in response to irradiating the target 10 with light 16, and a controller 8 for determining the UV coverage of an ultraviolet light protection formulation (UV protection formulation) 12 applied to the target 10 based on the image acquired by the detector 6.

[0035] The light source 2 may emit light 16 including ultraviolet light (UV light). The light source 2 may be a known light source, for example, a mercury lamp or an LED. For example, the light source 2 may emit light having a wide range of wavelengths including UV light, visible light, and infrared light. In this case, the light source 2 may include an optical filter 22 for transmitting only light having a desired wavelength range. Such a filter 22 may, for example, allow light having wavelengths in the UV light range to pass through. For example, the filter 22 may allow UV light, for example, light having a UV-A wavelength or a UV-B wavelength, or in particular UV light including a wavelength of 365 nm to pass through. Alternatively, the light source 2 may emit only UV light. For example, the light source 2 may emit monochromatic UV light, for example, light having a UV-A wavelength or a UV-B wavelength. Alternatively, specifically, the light source 2 may be a UV LED that emits UV light including a wavelength of 365 nm. When the light source 2 emits only UV light, the light source 2 does not need to include the filter 22.

[0036] The target 10 may be, for example, human skin, particularly the human face. The human skin may contain at least one fluorescent substance that may emit fluorescence 20 in the visible light range, for example, in response to light irradiation, particularly UV light irradiation. Such a fluorescent substance may be, for example, collagen, NADPH, or an amino acid. Alternatively, the target 10 may be a dummy sample containing a fluorescent substance similar to the fluorescent substance contained in human skin. Such a dummy sample may be, for example, pig skin, cultured human skin, or human skin modeled with a gel.

[0037] The UV protection preparation 12 applied on the target 10 may be, for example, a sunscreen. The UV protection preparation 12 may contain a material that absorbs and / or reflects UV light. Since a part of the light 16 that affects the target 10 is blocked by the UV protection preparation 12, the intensity of the light 16 that affects the target 10 depends on the amount of the UV protection preparation 12 applied on and remaining on the target 10. Since the intensity of the fluorescence 20 emitted from the target 10 also depends on the intensity of the light 16 incident on the target 10, the intensity of the fluorescence 20 emitted from the target 10 and affecting the detector 6 also depends on the amount of the UV protection preparation 12.

[0038] Detector 6 may detect the intensity of fluorescence 20 emitted from target 10 in response to the irradiation of light 16, and generate a signal according to the intensity. Alternatively, detector 6 may detect the two-dimensional distribution of the intensity of fluorescence 20 detected to generate a two-dimensional image having a brightness distribution corresponding to the intensity of fluorescence 20. Such a detector 6 may be a known photodetector having photosensitive elements arranged in an array. Detector 6 may be, for example, a CMOS camera or a CCD camera. The intensity of the light 16 reflected on the target 10 is generally much larger than the intensity of the fluorescence 20. Therefore, the reflected light 16 incident on the detector 6 may generate a large amount of noise, making it difficult to accurately measure the intensity of the fluorescence 20. Further, when the light 16 incident on the detector 6 has a large intensity, the detector 6 may be damaged. Therefore, the detector 6 may be provided with a shield 26 for blocking the light 16 reflected on the target 10. Further, the detector 6 may detect only the fluorescence 20 having a wavelength within a desired range for determining the UV coverage. For example, the detector 6 may have a relatively small sensitivity, or more preferably, may not have sensitivity to light having a wavelength outside the desired wavelength range. Alternatively, the detector 6 may be provided with a filter 24 for at least attenuating, preferably blocking, the fluorescence 20 having a wavelength outside the preferred wavelength range. The filter 24 may be configured to attenuate or block fluorescence having a wavelength other than between 290 nm and 420 nm by filtering. The filter 24 may also include a function of blocking the light 16 reflected on the target 10.

[0039] Controller 8 may be configured to control the emission of light 16 from light source 2, the detection by detector 6 of the fluorescence 20 emitted from target 10, and the generation of an image. Controller 8 may also be configured to determine the UV coverage of the UV protection formulation from the image acquired by detector 6. The determination of the UV coverage of the UV protection formulation will be described in detail below.

[0040] Figure 2 is a flowchart schematically showing a method 100 for determining the UV coverage of a UV protection formulation using device 1.

[0041] Method 100 includes a measurement process that includes steps 102 - 116. In step 102, the target 10 is irradiated with light 16 before the UV protection formulation 12 is applied, and fluorescence 20 emitted from the target 10 is detected to obtain a first image of the target 10.

[0042] In step 104, a predetermined amount of the UV protection formulation 12 is applied onto the target 10.

[0043] In step 106, the target 10 is irradiated with light 16, and fluorescence 20 emitted from the target 10 is detected to obtain a second image of the target 10.

[0044] In step 108, a predetermined stress is applied to the target 10 onto which the UV protection formulation 12 is applied. For example, as the stress, water may be sprayed onto the target 10 and then the target 10 may be wiped with a dry cloth. If the target 10 is a human face, the subject may perform an exercise such as running or rowing a bike and then wipe the sweat. The stress may also be just the passage of time. The stress may also be daily activities such as work or housework.

[0045] In step 110, the target 10 is irradiated with light 16, and fluorescence 20 emitted from the target 10 is detected to obtain an image of the target 10 after the stress is applied.

[0046] Steps 108 and 110 may be executed one or more times, for example, i times (i is an integer greater than or equal to 1) as needed, and images may be acquired multiple times. When step 108 is executed multiple times, step 110 may be executed for each step 108. Step 110 may be omitted after step 108 has been executed several times. In other words, step 110 may be executed once after step 108 has been repeated a predetermined number of times. A set of executing step 110 once after repeating step 108 a predetermined number of times may be executed a predetermined number of times. The image acquired at step 110 after step 108 has been executed i times is called the image after the i-th stress. When step 110 is executed after each step 108, the number of images acquired is i. When step 110 is omitted, fewer than i images are acquired.

[0047] The positions of the target 10 in the images acquired in steps 102, 106, and 110 are preferably at least similar, and more preferably the same, across all images. Further, the images are preferably acquired from at least a similar direction, and more preferably from the same direction. Thus, in order to match the direction of the image when acquiring the image in the steps after step 106 with the first image acquired in step 102 according to the position of the target 10 in the image, the step of adjusting the position and direction of the detector 6 may be executed before acquiring the image. Such adjustment may be executed by the operator's input or may be automatically executed by the controller 6 based on comparison with the first image. The adjustment by the operator may be executed using the controller 6 or may be executed without the controller 6.

[0048] In step 112, at least one region of interest is set on target 10 within the image acquired from the image acquisition step. The region of interest may preferably be at a common position across all images. If target 10 is, for example, a human face, the regions of interest may be set, for example, on the forehead, right cheek, and left cheek. When the images are adjusted such that the positions of the targets within the images are similar or identical, the regions of interest may be set at a common position without the need to finely adjust the positions for all images only when the region of interest is set for one image. For example, controller 6 may set the region of interest. The number, position, and size of the regions of interest can be appropriately set with respect to the purpose of measurement. When multiple regions of interest are set, the distribution of UV protection formulation 12 applied to target 10 can be obtained.

[0049] In step 114, the intensity of the detected light within the region of interest set in the image is obtained. The intensity of the detected light may correspond to the brightness within the region of interest, in other words, the grayscale value. Thus, the grayscale value may be used as an indicator representing the intensity of the detected light. The grayscale value may be obtained, for example, by averaging the grayscale values of the pixels within the region of interest.

[0050] In step 116, the UV coverage of UV protection formulation 12 may be determined by comparing the intensity of the detected light, for example, the grayscale value within the region of interest of the image in the image acquisition step. Various methods may be provided for determining the UV coverage. Preferably, the UV coverage is defined by the following formula.

[0051]

Equation

[0052] In the above formula, T0 is the intensity of the detected light obtained from the first image of target 10 before applying UV protection formulation 12 onto target 10, and T immis the intensity of the detected light obtained from the second image of the target 10 after applying the UV protection formulation 12 onto the target 10, T i is the intensity of the detected light obtained from the image after the i-th stress is applied to the target 10 coated with the UV protection formulation 12. The grayscale values within the region of interest in the image may be used as the intensity of the detected light as described above.

[0053] The detector 6 may preferably detect light in the blue range between the fluorescences 20. For example, if the detector 6 is a conventional CMOS camera or a CCD camera having an R channel, a G channel, and a B channel, the image may preferably be obtained by using only the data of the B channel. FIG. 3A shows the illumination spectrum of Visia UV light with a peak at 365.9 nm and a range from 290 nm to 420 nm. FIG. 3B shows the intensities of the fluorescences in the R channel, G channel, and B channel emitted from human skin in response to the irradiation of UV light. It is shown that the intensity in the B channel is the highest. FIG. 4 shows the images of the fluorescences in the R channel, G channel, and B channel emitted from human skin in response to the irradiation of UV light. It is shown that the image of the B channel has the maximum brightness and the highest contrast. Therefore, when the data in the B channel is used, the UV coverage may be determined with high resolution and high precision. Further, the detector 6 may include a filter 24 for attenuating or blocking light having wavelengths other than the B channel wavelength. The filter 24 may attenuate or block light having wavelengths outside the range between 290 nm and 420 nm.

[0054] To compare the device 1 and the method 100 with the conventional method shown in FIG. 10, the changes in the UV coverage and the intensity of the fluorescence were determined by the following procedure.

[0055] First, the pre - preparation was carried out. The subject washed their face using cleansing oil and a foaming cleanser. Then, 1.0 mL of lotion and 0.6 mL of emulsion were applied to the entire face to provide moisture. Next, the subject was acclimated for 15 minutes at 22 °C and 45% humidity.

[0056] Next, measurements were taken before applying the UV - protecting formulation. Specifically, the subject's face was irradiated with UV light by using Device 1, and a first image was acquired based on the fluorescence emitted from the face. Additionally, the left and right sides of the forehead and the left and right cheeks were irradiated with UV light, and the intensity of the emitted fluorescence was measured by a conventional method.

[0057] After the measurement, 150 mg of two types of UV - protecting formulations (858419 5) and (884474 1) were applied to the left and right sides of the face, respectively. Then, the subject was acclimated for 15 minutes at 22 °C and 45% humidity.

[0058] Next, measurements were taken after applying the UV - protecting formulation. Specifically, a second image was acquired by using Device 1. The intensity of the fluorescence was also measured by a conventional method.

[0059] Next, the subject had a light meal within 30 minutes in an environment of 22 °C and 45% humidity. After the meal, as the first stress, the operator sprayed 2.5 g of water mist onto the entire face from a distance of 20 cm for 3 seconds. Then, a paper towel was applied to the entire face to remove the moisture.

[0060] Next, measurements were taken after the first stress. Specifically, an image after the first stress was acquired by using Device 1. The intensity of the fluorescence was also measured by a conventional method.

[0061] As the second stress, the subject spent 40 minutes in an environment of 30 - 32°C and 30% humidity, and then exercised on a fitness bike for 10 minutes in an environment of 20 - 30°C and 30% humidity. During the exercise, the subject was required to maintain a heart rate of 130 beats per minute. Next, a paper towel was applied to the entire face to remove sweat. The subject was acclimatized at 22°C and 45% humidity for 30 minutes.

[0062] Subsequently, measurements after the second stress were performed. Specifically, an image after the second stress was acquired by using Device 1. The fluorescence intensity was also measured by the conventional method.

[0063] As the third stress, the operator wiped each surface of the subject's face twice with absorbent cotton.

[0064] Next, measurements after the third stress were performed. Specifically, an image after the third stress was acquired by using Device 1. The fluorescence intensity was also measured by the conventional method.

[0065] Thereafter, as shown in FIG. 5, regions of interest were set on the left and right sides of the forehead and the left and right cheeks by using Device 1. The regions of interest were set such that the regions where the fluorescence intensity was measured by the conventional method were included in the regions of interest. The grayscale value of the regions of interest was determined by averaging the grayscale values in the regions of interest within the image.

[0066] Subsequently, based on the grayscale value in the region of interest of the image, the UV coverage after applying the i-th stress was determined using the following formula.

[0067]

Equation

[0068] In the above formula, T0 is the grayscale value obtained from the first image of the subject's face before applying the UV protection preparation to the subject's face, and T immis the grayscale value obtained from the second image of the subject's face after applying the UV protection preparation to the subject's face, T i is the grayscale value obtained from the image after applying the i-th stress to the face of the subject to whom the UV protection preparation has been applied. As described above, the grayscale value corresponds to the intensity of fluorescence emitted and detected from the subject's face.

[0069] Similarly, the change in fluorescence obtained by the conventional method after the i-th stress was determined by the following formula.

[0070] [Number]

[0071] In the above formula, T imm is the intensity of fluorescence from the subject's face measured based on the conventional method after applying the UV protection preparation to the subject's face, and T i is the intensity of fluorescence measured based on the conventional method after applying the i-th stress to the face of the subject to whom the UV protection preparation has been applied.

[0072] Figure 6 shows the UV coverage obtained by the method of the present invention. It can be seen that the UV coverage decreases each time stress is applied to two types of UV protection preparations (858419 5) and (884474 1) applied to the forehead and cheeks.

[0073] Figure 7 shows the change in the intensity of fluorescence obtained by the conventional method shown in Figure 10 for comparison. It can be seen that the intensity of fluorescence increases each time stress is applied to two types of UV protection preparations (858419 5) and (884474 1) applied to the forehead and cheeks.

[0074] Figure 8 shows the correlation between the UV coverage obtained by the method of the present invention and the change in the intensity of fluorescence obtained by the conventional method. The UV coverage shows a good correlation with the change in the intensity of fluorescence. Thus, it can be seen that the UV protection effect of the UV protection preparation can be evaluated by measuring the UV coverage rather than the change in the intensity of fluorescence. Different from the conventional method, the method of the present invention can simultaneously obtain the UV coverage in a plurality of parts within the image of the target. Therefore, the UV protection effects of the UV protection preparation in a plurality of parts of the target can be simultaneously evaluated, and the distribution of the UV protection preparation can also be evaluated.

[0075] Furthermore, Figure 9 shows the UV coverage obtained by the method of the present invention for two types of UV protection preparations (858419 5) and (884474 1). Figure 9 shows that (884474 1) has higher resistance to stress than (858419 5). Since the method of the present invention can evaluate the UV coverage of a plurality of types of UV protection preparations applied to different parts on the target, different types of UV protection preparations can be easily and accurately compared with each other.

[0076] Although specific embodiments of the present invention have been described, it will be readily understood by those skilled in the art that various changes, modifications, and improvements can be made without departing from the technical spirit and scope of the present invention.

Explanation of Reference Numerals

[0077] 1 Device for determining UV coverage 2 Light source 6 Detector 8 Controller 10 Target 12 UV protection preparation 16 Light 20 Fluorescence 22 Filter of light source 24 Filter of detector 26 Shield 1006 Optical sensor 1010 Target 1016 light 1020 fluorescence

Claims

1. A method for determining the UV coverage of a UV protection formulation by a measurement process, comprising: Before applying the UV protection formulation onto a target, irradiating the target with light from a light source, detecting fluorescence emitted from the target in response to the irradiation of the light by a detector, and obtaining a fluorescence image of the target; After applying the UV protection formulation onto the target, irradiating the target with light from the light source, detecting fluorescence emitted from the target in response to the irradiation of the light by the detector, and obtaining an image of the target; After applying stress to the target coated with the UV protection formulation, irradiating the target with light from the light source, detecting fluorescence emitted from the target in response to the irradiation of the light by the detector, and obtaining an image of the target; Setting at least one region of interest on the target in each image obtained in each image acquisition step; Obtaining the intensity of light detected within the region of interest in each image obtained from the image acquisition steps; Determining the UV coverage of the UV protection formulation by comparing the intensities of the light detected in the region of interest in each image obtained from the image acquisition steps, wherein the UV coverage of the UV protection formulation is determined based on the following formula: 【Number 1】 In the above formula, T0 represents the intensity of the detected light obtained from the fluorescence image of the target before applying the UV protection formulation, Timm represents the intensity of the detected light obtained from the fluorescence image of the target after applying the UV protection formulation onto the target, Ti represents the intensity of the detected light obtained from the fluorescence image of the target after applying the i-th stress to the target coated with the UV protection formulation, and i represents an integer of 1 or more. The method includes the above steps.

2. The method according to claim 1, wherein the step of, after applying stress to the target coated with the UV protection formulation, irradiating the target with light from the light source, detecting fluorescence emitted from the target in response to the irradiation of the light by the detector, and obtaining the fluorescence image of the target is performed once or multiple times.

3. The method according to claim 1, wherein the step of obtaining the fluorescence image of the target includes a step of attenuating or blocking fluorescence having a wavelength in a range other than between 290 nm and 420 nm by filtering.

4. The method according to claim 1, wherein the target is a human face or a dummy sample containing a fluorescent substance similar to the fluorescent substance contained in human skin.

5. The step of setting the at least one region of interest includes a step of setting a plurality of regions of interest on a human face, The method according to claim 1, wherein the step of determining the UV coverage includes a step of simultaneously determining the UV coverage in the plurality of regions of interest.

6. The method according to claim 1, wherein the light for irradiating the target has a wavelength in the ultraviolet range.

7. A device for determining the UV coverage of a UV protection preparation, a light source for irradiating a target with light, a detector that irradiates the target with light from the light source, detects fluorescence emitted from the target in response to the irradiation of the light, and obtains a fluorescence image of the target, a controller for determining the UV coverage of the UV protection preparation applied on the target based on the fluorescence image of the target obtained by the detector, the controller is configured to set at least one region of interest on the target in the fluorescence image, the controller determines the UV coverage of the UV protection preparation by comparing the intensities of the detected light in the region of interest in the image of the target before applying the UV protection preparation on the target, the image of the target after applying the UV protection preparation on the target, and the image of the target after applying stress to the target on which the UV protection preparation is applied, and the determination is configured to determine the UV coverage of the UV protection preparation based on the following formula: 【Number 2】 In the above formula, T0 represents the intensity of the detected light obtained from the fluorescence image of the target before applying the UV protection formulation onto the target, Timm represents the intensity of the detected light obtained from the fluorescence image of the target after applying the UV protection formulation onto the target, Ti represents the intensity of the detected light obtained from the fluorescence image of the target after applying the i-th stress to the target onto which the UV protection formulation has been applied, and i represents an integer of 1 or more, and the device is configured as such.

8. The device according to claim 7, wherein the fluorescence image of the target after applying the stress to the UV protection formulation applied onto the target is acquired one or more times.

9. The device according to claim 7, wherein the detector comprises a filter configured to attenuate or block fluorescence having a wavelength in a range other than between 420 nm and 520 nm by filtering.

10. The device according to claim 7, wherein the target is a human face or a dummy sample containing a fluorescent substance similar to the fluorescent substance contained in human skin.

11. The at least one region of interest is a plurality of regions of interest on a human face, The device according to claim 7, wherein the controller is configured to simultaneously determine the UV coverage in the plurality of regions of interest.

12. The device according to claim 7, wherein the light source is configured to irradiate the target with light having a wavelength in the ultraviolet range.

Images