JP2022163456A - Method and device for determining uv coverage percentage after applying real life stress - Google Patents

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

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

Protecting targets such as human skin from ultraviolet light (UV protection) is important for skin health and beauty. After applying a formulation with a UV protective effect, i.e. after the sunscreen has been applied onto the target, the sunscreen will eventually be exposed to other factors such as wetting the target, wiping the target with a towel, or allowing time to pass. Removed by stress on sunscreen. Therefore, sunscreen efficacy is eventually lost through stress and the passage of time. In order to effectively protect targets, it is necessary to measure the current protective effectiveness. However, since ultraviolet light is invisible to the human eye, the UV protection effect is also not visible. Therefore, the consumer cannot visually inspect the extent to which UV protection is maintained.

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

FIG. 10 shows a conventional method of determining the intensity of fluorescence emitted from a target in response to irradiation with UV light. In this method, a target 1010 is illuminated with light 1016 that includes UV light. Target 1010 emits fluorescence 1020 in response to irradiation with light 1016 . When fluorescent light 1020 impinges on optical sensor 1006 , optical sensor 1006 outputs a signal according to the intensity of fluorescent light 1020 . The change in fluorescence intensity is calculated by the following formula.

where T _imm represents the intensity of fluorescence measured immediately after applying the UV protection formulation onto the target, and T _i represents the intensity of fluorescence measured after a given number of stresses were applied to the UV protection formulation. represents

However, this conventional method can only measure a portion of the target at a time. For example, when the target is a human face, it is difficult to simultaneously evaluate the UV protection effect in multiple parts of the face such as the forehead and left and right cheeks, and to evaluate the distribution of the UV protection effect.

An imaging system has been developed that can obtain a standard image of a human face as a target under certain illumination conditions. For example, Canfield Scientific, Inc. Visia system is commercially available. The UV imaging capabilities of such imaging systems are often used to deduce and show pigmentation spots that significantly absorb UV light. Additionally, UV imaging capabilities are often used as an example to demonstrate the efficacy of UV protection formulations. However, to the best of the inventor's knowledge, such imaging systems have not been used to directly quantify temporal variations in the distribution of UV protective formulations on the surface of the skin. (1999) reported the use of blue fluorescent pigments to estimate the resistance of UV protection formulations to some types of water.

Other systems developed by L'Oreal, such as UV Patch, aim to obtain real-time data and changes in UV protection levels based on photosensitive patches that occur in response to UV irradiation. UV patches have the advantage of being portable, but the purpose of UV patches is not to assess the distribution of an applied UV protection formulation. Additionally, UV patches require intentional exposure to UV light, in other words, UV patches do not react unless exposed to sunlight.

Ｃｈｕｔｉｍａ Ｒｕｎｇａｎａｎｃｈａｉら、“Ｓｕｎｓｃｒｅｅｎ Ａｐｐｌｉｃａｔｉｏｎ ｔｏ ｔｈｅ Ｆａｃｅ Ｐｅｒｓｉｓｔｓ ｂｅｙｏｎｄ ２ Ｈｏｕｒｓ ｉｎ Ｉｎｄｏｏｒ Ｗｏｒｋｅｒｓ； ａｎ Ｏｐｅｎ－Ｌａｂｅｌ Ｔｒｉａｌ”、Ｊｏｕｒｎａｌ ｏｆ Ｄｅｒｍａｔｏｌｏｇｉｃａｌ Ｔｒｅａｔｍｅｎｔ、第３０巻、２０１９年、第５号、４８３頁－４８６頁

The purpose of the present invention is to quantify the change in spatial distribution of the UV protection formulation and its uniformity for an initial uniform application of a sufficient amount of the UV protection formulation, called "UV coverage". It should be noted that the purpose of the present invention is not to estimate the UV Protection Factor SPF of UV protection formulations applied on the surface of the skin.

A method for determining the UV coverage of a UV protection formulation by a measurement process according to an embodiment of the invention comprises:
acquiring an image of the target by illuminating the target prior to applying the UV protective formulation onto the target;
obtaining an image of the target by illuminating the target after applying the UV protective formulation onto the target;
acquiring an image of the target by irradiating the target with light after stressing the target to which the UV protective formulation has been applied;
establishing at least one region of interest on the target in the image acquired in each image acquisition step;
obtaining the intensity of the detected light within the region of interest in the image obtained from the image obtaining step;
and determining the UV coverage of the UV protective formulation by comparing the detected light intensity in the regions of interest in the images acquired from the image acquisition step.

In one embodiment of the invention, the step of acquiring an image of the target by irradiating the target with light after applying stress to the target coated with the UV protective formulation may be performed one or more times.

In one embodiment of the invention, determining the UV coverage of the UV protection formulation may determine the UV coverage of the UV protection formulation based on the following formula:

where T ₀ represents the intensity of the detected light obtained from the image of the target before applying the UV protection formulation and T _imm is the intensity from the image of the target after applying the UV protection formulation on the target. represents the intensity of the detected light acquired, T _i represents the intensity of the detected light acquired from the image of the target after the i-th stress of the target coated with the UV protective formulation, i represents an integer of 1 or more.

In one embodiment of the invention, acquiring an image of the target may comprise acquiring an image of fluorescence emitted from the target in response to illuminating the target.

In one embodiment of the invention, acquiring an image of the target may include filtering to attenuate or block fluorescence having wavelengths outside the range between 290 nm and 420 nm.

In one embodiment of the invention, the target may be a human face or a dummy sample containing fluorescent material similar to that contained in human skin.

In one embodiment of the present invention, establishing at least one region of interest may comprise establishing multiple regions of interest on the human face, and determining UV coverage comprises: simultaneously determining the UV coverage in the .

In one embodiment of the invention, the light for illuminating the target may have a wavelength in the ultraviolet light range.

A device for determining the UV coverage of a UV protection formulation according to one embodiment of the invention comprises:
a light source for illuminating the target;
a detector for obtaining an image of the target in response to illuminating the target;
a controller for determining UV coverage of a UV protective formulation applied on the target based on the image of the target acquired by the detector;
The controller is configured to set at least one region of interest on the target in the image;
The controller provides an image of the target before applying the UV protective formulation onto the target, an image of the target after applying the UV protective formulation onto the target, and a target after stressing the target with the UV protective formulation applied. is configured to determine the UV coverage of the UV protective formulation by comparing the detected light intensity in the region of interest in the image of the.

In one embodiment of the invention, one or more images of the target after stressing the target to which the UV protective formulation has been applied may be acquired.

In one embodiment of the invention, the controller may be configured to determine the UV coverage of the UV protection formulation based on the formula:

where T ₀ represents the intensity of the detected light obtained from the image of the target before applying the UV protective formulation on the target, and T _imm is the intensity of the target after applying the UV protective formulation on the target. and T _i represents the detected light intensity obtained from the image of the target after the i-th stress of the target coated with the UV protective formulation. and i represents an integer of 1 or more.

In one embodiment of the invention, the detector may be configured to acquire an image of fluorescence emitted from the target in response to illuminating the target.

In one embodiment of the invention, the detector may comprise a filter configured to attenuate or block fluorescence having wavelengths outside the range between 420 nm and 520 nm by filtering.

In one embodiment of the invention, the target may be a human face or a dummy sample containing fluorescent material similar to that contained in human skin.

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

In one embodiment of the invention, the light source may be configured to illuminate the target with light having a wavelength in the ultraviolet light range.

According to the present invention, methods and devices are provided for determining UV coverage of UV protection formulations.

1 is a schematic diagram of a device for determining UV coverage of UV protection formulations, according to some embodiments of the present invention; FIG. FIG. 2 schematically illustrates a flowchart of a method for determining UV coverage of UV protection formulations, according to some embodiments of the present invention; Fig. 2 shows the illumination spectrum of Visia UV light with a range from 290nm to 420nm; FIG. 4 shows the intensity in the R, G, and B channels of fluorescence emitted from human skin in response to irradiation with UV light in a method for determining UV coverage of a UV protective formulation according to some embodiments of the present invention; is. FIG. 3 shows images of fluorescence acquired in the R, G, and B channels in a method for determining UV coverage of UV protective formulations according to some embodiments of the present invention; FIG. 10 illustrates an example of setting a region of interest on a target in a method of determining UV coverage of a UV protective formulation, according to some embodiments of the present invention; FIG. 3 illustrates UV coverage obtained by a method for determining UV coverage of UV protection formulations, according to some embodiments of the present invention; FIG. 13 shows changes in fluorescence obtained by a conventional method for comparison; FIG. 4 shows the correlation between UV coverage obtained by methods according to some embodiments of the present invention and changes in fluorescence obtained by conventional methods. FIG. 3 illustrates the UV coverage obtained for different types of UV protection formulations by the method for determining UV coverage of UV protection formulations, according to some embodiments of the present invention; 1 illustrates a conventional method of measuring the intensity of fluorescence emitted from a target in response to irradiating the target with UV light; FIG.

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

The light source 2 may emit light 16 including ultraviolet light (UV light). The light source 2 may be a known light source such as a mercury lamp or an LED. For example, 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 comprise an optical filter 22 for transmitting only light having the desired wavelength range. Such a filter 22 may, for example, allow light having wavelengths in the UV light range to pass. For example, filter 22 may allow UV light to pass, for example light having UV-A or UV-B wavelengths, or in particular UV light including wavelengths of 365 nm. Alternatively, light source 2 may emit only UV light. For example, the light source 2 may emit monochromatic UV light, eg light having UV-A or UV-B wavelengths. Alternatively, in particular, the light source 2 may be a UV LED emitting UV light containing a wavelength of 365 nm. If the light source 2 emits only UV light, the light source 2 need not be equipped with the filter 22 .

Target 10 may be, for example, human skin, in particular a human face. Human skin may comprise at least one fluorescent material that may emit fluorescence 20 in the visible light range, for example, upon irradiation with light, in particular UV light. Such fluorescent substances may be collagen, NADPH, or amino acids, for example. Alternatively, target 10 may be a dummy sample containing fluorescent material similar to that contained in human skin. Such a dummy sample may be, for example, pig skin, cultured human skin, or gel modeled human skin.

The UV protection formulation 12 applied on the target 10 may be, for example, a sunscreen. UV protection formulation 12 may include materials that absorb and/or reflect UV light. Since part of the light 16 impinging on the target 10 is blocked by the UV protection formulation 12 , the intensity of the light 16 impinging on the target 10 is reduced by the UV protection formulation 12 applied on the target 10 and remaining on the target 10 . depends on the amount of 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 impinging on the detector 6 also depends on the UV protection formulation 12 . Depends on quantity.

Detector 6 may detect the intensity of fluorescence 20 emitted from target 10 in response to illumination with light 16 and generate a signal in response to the intensity. Alternatively, the detector 6 may detect the two-dimensional distribution of the intensity of the detected fluorescence 20 to produce a two-dimensional image with a distribution of brightness corresponding to the intensity of the fluorescence 20 . Such 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 light 16 reflected on target 10 is generally much greater than the intensity of fluorescent light 20 . Therefore, the reflected light 16 impinging on the detector 6 may produce a large amount of noise, making accurate measurement of the intensity of the fluorescence 20 difficult. Furthermore, if the light 16 impinging on the detector 6 has a high intensity, the detector 6 can be damaged. Detector 6 may therefore comprise a shield 26 for blocking light 16 reflected on target 10 . Further, detector 6 may detect fluorescence 20 only having wavelengths within a desired range for determining UV coverage. For example, the detector 6 may have relatively little sensitivity, or more preferably no sensitivity to light having wavelengths outside the desired wavelength range. Alternatively, detector 6 may comprise a filter 24 that at least attenuates, preferably blocks, fluorescence 20 having wavelengths outside the preferred wavelength range. Filter 24 may be configured to attenuate or block fluorescence at wavelengths other than between 290 nm and 420 nm by filtering. Filter 24 may also include the ability to block light 16 reflected onto target 10 .

Controller 8 may be configured to control the emission of light 16 from light source 2, the detection by detector 6 of fluorescent light 20 emitted from target 10, and the generation of images. Controller 8 may also be configured to determine the UV coverage of the UV protection formulation from the images acquired by detector 6 . Determination of UV coverage of UV protection formulations is described in detail below.

FIG. 2 is a flow chart that schematically illustrates a method 100 for determining UV coverage of UV protection formulations using device 1 .

Method 100 includes a measurement process including steps 102-116. At step 102 , the target 10 is illuminated with light 16 before the UV protective formulation 12 is applied, and fluorescence 20 emitted from the target 10 is detected to obtain a first image of the target 10 .

At step 104 a predetermined amount of UV protection formulation 12 is applied onto the target 10 .

At step 106 , target 10 is illuminated with light 16 and fluorescent light 20 emitted from target 10 is detected to obtain a second image of target 10 .

At step 108, a predetermined stress is applied to the target 10 with the UV protective formulation 12 applied. For example, water may be sprayed onto the target 10 as a stress, and then the target 10 may be wiped with a dry cloth. If the target 10 is a human face, the subject may exercise, such as running or biking, and then wipe off sweat. Stress may also be simply the passage of time. Stress can also be everyday activities such as work or household chores.

At step 110, the target 10 is illuminated with light 16 and fluorescence 20 emitted from the target 10 is detected to obtain an image of the target 10 after applying stress.

Steps 108 and 110 may be performed one or more times, eg, i times (where i is an integer equal to or greater than 1), as needed, and images may be acquired multiple times. If step 108 is performed multiple times, step 110 may be performed for each step 108 . Step 110 may be omitted after performing step 108 several times. In other words, step 110 may be performed once after repeating step 108 a predetermined number of times. A set of performing step 110 once after repeating step 108 a predetermined number of times may be performed a predetermined number of times. The image obtained in step 110 after performing step 108 i times is called the i post-stress image. If step 110 is performed after each step 108, the number of images acquired is i. If step 110 is omitted, less than i images are acquired.

The positions of the target 10 in the images acquired in steps 102, 106 and 110 are preferably at least similar, more preferably identical, across all images. Further, the images are preferably obtained from at least similar directions, more preferably from the same directions. Therefore, the position of the target 10 in the image causes the position of the detector 6 and Adjusting the orientation may be performed prior to acquiring the image. Such adjustments may be performed by operator input, or may be performed automatically by controller 6 based on comparison with the first image. Adjustments by the operator may be performed with controller 6 or without controller 6 .

At step 112, at least one region of interest is established on the target 10 in the image obtained from the image acquisition step. The region of interest may preferably be a common location across all images. If the 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. If the images are adjusted such that the positions of the targets in the images are similar or identical, the regions of interest can be adjusted for all images without having to fine-tune the positions only if the regions of interest are set for one image. It may be set in a common position. For example, controller 6 may set the region of interest. The number, location and size of the regions of interest can be set appropriately for the purpose of the measurement. By setting multiple regions of interest, the distribution of the UV protection formulation 12 applied to the target 10 can be obtained.

At 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. The grayscale value may therefore be used as an indicator of the intensity of the detected light. A grayscale value may be obtained, for example, by averaging the grayscale values of the pixels in the region of interest.

At step 116, the UV coverage of the UV protective formulation 12 may be determined by comparing the detected light intensity, eg, the grayscale value within the region of interest of the image in the image acquisition step. Various methods may be provided to determine UV coverage. Preferably, the UV coverage is defined by the formula below.

where T ₀ is the detected light intensity obtained from the first image of the target 10 before applying the UV protective formulation 12 onto the target 10 , and T _imm is the UV protective formulation 12 applied on the target 10 . is the detected light intensity obtained from the second image of the target 10 after application on the target 10, and T _i is the intensity of the light detected after the i-th stress on the target 10 with the UV protective formulation 12 applied. Detected light intensity obtained from the i-th post-stress image obtained. The grayscale value within the region of interest in the image may be used as the detected light intensity as described above.

Detector 6 may preferably detect light in the blue range between fluorescence 20 . For example, if the detector 6 is a conventional CMOS or CCD camera having R, G and B channels, images may preferably be acquired by using only the B channel data. 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 intensity of fluorescence in R, G, and B channels emitted from human skin in response to irradiation with UV light. The intensity in the B channel is shown to be highest. FIG. 4 shows images of fluorescence in the R, G, and B channels emitted from human skin in response to irradiation with UV light. The B channel image is shown to have the highest brightness and highest contrast. Therefore, UV coverage may be determined with high resolution and accuracy when data in the B channel is used. Additionally, the detector 6 may comprise a filter 24 for attenuating or blocking light having wavelengths other than the B-channel wavelengths. Filter 24 may attenuate or block light having wavelengths outside the range between 290 nm and 420 nm.

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

First, a preliminary preparation was performed. Subjects washed their faces with cleansing oil and foaming cleanser. After that, 1.0 mL of lotion and 0.6 mL of emulsion were applied all over the face for moisturizing. It was then acclimated for 15 minutes at 22°C and 45% humidity.

Measurements were then carried out before applying the UV protection formulation. Specifically, the device 1 was used to irradiate the subject's face with UV light and a first image was acquired based on the fluorescence emitted from the face. In addition, the left and right sides of the forehead and the left and right cheeks were irradiated with UV light and the intensity of emitted fluorescence was measured by conventional methods.

After measurement, 150 mg of two UV protection formulations (858419 5) and (884474 1) were applied to the left and right sides of the face, respectively. It was then acclimated for 15 minutes at 22°C and 45% humidity.

Measurements were then carried out after application of the UV protection formulation. Specifically, a second image was acquired by using Device 1 . Fluorescence intensity was also measured by conventional methods.

Subjects then ate a light meal within 30 minutes in an environment of 22°C and 45% humidity. After eating, the operator sprayed 2.5 g of water mist over the entire face from a distance of 20 cm for 3 seconds as a first stress. A paper towel was then applied over the face to remove moisture.

A first post-stress measurement was then performed. Specifically, a first post-stress image was acquired by using Device 1 . Fluorescence intensity was also measured by conventional methods.

As a second stress, subjects spent 40 minutes in an environment of 30-32° C. and 30% humidity, and exercised on a fitness bike for 10 minutes in an environment of 20-30° C. and 30% humidity. Subjects were asked to maintain a heart rate of 130 beats/minute during exercise. A paper towel was then applied over the face to remove sweat. Acclimatization for 30 minutes at 22° C. and 45% humidity.

A second post-stress measurement was then performed. Specifically, a second post-stress image was acquired by using Device 1 . Fluorescence intensity was also measured by conventional methods.

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

A third post-stress measurement was then performed. Specifically, a third post-stress image was acquired by using Device 1 . Fluorescence intensity was also measured by conventional methods.

Then, regions of interest were set on the left and right sides of the forehead and on the left and right cheeks by using Device 1 as shown in FIG. The region of interest was set so as to include the region whose fluorescence intensity was measured by the conventional method. The grayscale value of the region of interest was determined by averaging the grayscale values in the region of interest within the image.

The UV coverage after the ith stress was then determined using the following formula based on the grayscale values in the region of interest of the image.

where T ₀ is the grayscale value obtained from the first image of the subject's face before the UV protection formulation is applied to the subject's face, and T _imm is the UV protection formulation applied to the subject's face. is the grayscale value obtained from the second image of the subject's face after application, T _i is the grayscale value obtained from the image after the ith stress on the subject's face to which the UV protective formulation was applied. scale value. As mentioned above, the grayscale values correspond to the intensity of detected fluorescence emitted from the subject's face.

Similarly, the change in fluorescence obtained by the conventional method after the i-th stress was determined by the following equation.

where T _imm is the intensity of fluorescence from the subject's face measured according to conventional methods after the UV protection formulation was applied to the subject's face, and T _i is the UV protection formulation applied. Intensity of fluorescence measured according to the conventional method after the ith stress on the subject's face.

FIG. 6 shows the UV coverage obtained by the method of the invention. It can be seen that the UV coverage decreases with each stress for the two UV protection formulations (858419 5) and (884474 1) applied to the forehead and cheeks.

FIG. 7 shows changes in fluorescence intensity obtained by the conventional method shown in FIG. 10 for comparison. It can be seen that the fluorescence intensity increases with each stress for the two UV protection formulations (858419 5) and (884474 1) applied to the forehead and cheeks.

FIG. 8 shows the correlation between the UV coverage obtained by the method of the invention and the change in fluorescence intensity obtained by the conventional method. UV coverage shows a good correlation with changes in fluorescence intensity, thus demonstrating that UV protection efficacy of UV protection formulations can be evaluated by measuring UV coverage rather than changes in fluorescence intensity. Unlike conventional methods, the method of the present invention can simultaneously acquire UV coverage at multiple portions in the image of the target, thus simultaneously assessing the UV protection efficacy of UV protection formulations at multiple portions of the target. , the distribution of UV protection formulations can also be evaluated.

Further, Figure 9 shows the UV coverage obtained by the method of the invention for two UV protection formulations (858419 5) and (884474 1). Figure 9 shows that (884474 1) has a higher tolerance to stress than (858419 5). Since the method of the present invention can evaluate the UV coverage of multiple types of UV protection formulations applied to different portions of the target, it is possible to easily and accurately compare different types of UV protection formulations. can.

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

1 device for determining UV coverage 2 light source 6 detector 8 controller 10 target 12 UV protective formulation 16 light 20 fluorescence 22 light source filter 24 detector filter 26 shield 1006 light sensor 1010 target 1016 light 1020 fluorescence

Claims (16)

A method for determining UV coverage of a UV protection formulation by a measurement process, comprising:
acquiring an image of the target by illuminating the target prior to applying a UV protective formulation onto the target;
obtaining an image of the target by illuminating the target after applying the UV protective formulation onto the target;
acquiring an image of the target by irradiating the target with light after applying stress to the target coated with the UV protective formulation;
establishing at least one region of interest on the target in the image acquired in each image acquisition step;
obtaining the intensity of detected light within the region of interest in the image obtained from the image obtaining step;
and determining the UV coverage of the UV protective formulation by comparing the intensity of the detected light in the region of interest within the image obtained from the image obtaining step. 2. The step of acquiring the image of the target by irradiating the target with light after applying the stress to the target coated with the UV protective formulation is performed one or more times. described method. The step of determining the UV coverage of the UV protection formulation comprises determining the UV coverage of the UV protection formulation based on the formula:

where T ₀ represents the detected light intensity obtained from the image of the target prior to applying the UV protection formulation, and T _imm is the UV protection formulation applied onto the target. T i represents the intensity of the detected light obtained from the image of the target after applying the UV protective formulation, and T _i is 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 protective formulation. 2. The method of claim 1, wherein i represents the intensity of the detected light obtained and i represents an integer greater than or equal to 1. 2. The method of claim 1, wherein acquiring the image of the target comprises acquiring an image of fluorescence emitted from the target in response to illuminating the target. 2. The method of claim 1, wherein the step of acquiring the image of the target comprises filtering to attenuate or block fluorescence having wavelengths in a range other than between 290 nm and 420 nm. 2. The method of claim 1, wherein the target is a human face or a dummy sample containing fluorescent material similar to that contained in human skin. said step of establishing said at least one region of interest comprises establishing a plurality of regions of interest on a human face;
2. The method of claim 1, wherein determining the UV coverage comprises determining the UV coverage in the plurality of regions of interest simultaneously. 2. The method of claim 1, wherein the light for illuminating the target has a wavelength in the ultraviolet light range. A device for determining the UV coverage of a UV protection formulation, comprising:
a light source for illuminating the target;
a detector for obtaining an image of the target in response to illuminating the target;
a controller for determining UV coverage of a UV protective formulation applied onto the target based on the image of the target acquired by the detector;
the controller is configured to establish at least one region of interest on the target in the image;
The controller provides an image of the target before applying the UV protective formulation onto the target, an image of the target after applying the UV protective formulation onto the target, and an image of the target with the UV protective formulation applied. A device configured to determine the UV coverage of the UV protective formulation by comparing the detected light intensity in the region of interest in an image of the target after subjecting the target to stress. 10. The device of claim 9, wherein the image of the target after applying the stress to the UV protective formulation applied on the target is acquired one or more times. The controller is configured to determine the UV coverage of the UV protection formulation based on the formula:

where T ₀ represents the intensity of the detected light obtained from the image of the target prior to applying the UV protection formulation onto the target, and T _imm represents the UV protection formulation to the target. represents the intensity of the detected light obtained from the image of the target after application on a target, and T _i is the intensity of the detected light after the i-th stress on the target coated with the UV protective formulation; 10. The device of claim 9, wherein i represents an integer greater than or equal to 1 and represents the intensity of the detected light obtained from the image of . 10. The device of Claim 9, wherein the detector is configured to acquire an image of fluorescence emitted from the target in response to illuminating the target. 10. The device of Claim 9, wherein the detector comprises a filter configured to attenuate or block fluorescence having wavelengths in a range other than between 420 nm and 520 nm by filtering. 10. The device of claim 9, wherein the target is a human face or a dummy sample containing fluorescent material similar to that contained in human skin. the at least one region of interest is a plurality of regions of interest on a human face;
10. The device of Claim 9, wherein the controller is configured to determine the UV coverage in the multiple regions of interest simultaneously. 10. The device of Claim 9, wherein the light source is configured to illuminate the target with light having a wavelength in the ultraviolet light range.

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