GB2593174A - Sunscreen application assessment - Google Patents

Abstract

A method for assessing the effectiveness of sunscreen application to skin comprises identifying 103 areas of an unfiltered digital image as containing exposed skin; determining areas of a UV filtered digital image that contain exposed skin by correspondence with the unfiltered digital image; extracting 104 image characteristics of the exposed skin areas in the UV filtered digital image; and generating an assessment of the effectiveness of sunscreen application to the exposed skin area for output. The assessment of the effectiveness of the application of the sunblock is generated on the basis of the extracted image characteristics of the skin area in the UV filtered image. The filtered and unfiltered images may be captured by the same camera, which may be integrated into a device such as a smartphone. The sun cream application effectiveness assessment may comprise the combination 105 of the extracted image characteristics with the unfiltered image to generate an augmented image for output.

Description

SUNSCREEN APPLICATION ASSESSMENT Technical Field of the Invention The present invention relates to sunscreen application assessment. In particular, the present invention relates to a method and apparatus for assessing sunscreen application.

Background to the Invention

In order to provide exposed skin with protection against solar radiation when outdoors, it is common for individuals to use sunscreen. The sunscreen is generally applied directly to the skin and lies on or is absorbed into the skin. The sunscreen acts to absorb or reflect ultraviolet (UV) light thus preventing the UV light from causing damage to skin cells. Typically, sunscreen is active to reflect or absorb at least UVA band light (315nm-400nm).

Most sunscreen, once absorbed into the skin, is essentially transparent in most of the visible light range and is thus not visible to the naked eye. Whilst this is beneficial for cosmetic reasons it does mean that sunscreen coverage is not readily assessed by simple visual inspection. As such, it is very easy for insufficient sunscreen to be applied to an area of skin or for sunscreen to be entirely omitted from an area of skin. Such incorrect or incomplete application of sunscreen before exposure to solar radiation can cause serious consequences, particularly for those with sensitive or young skin.

It is therefore an object of the present invention to provide means to at least partially overcome or alleviate this problem.

Summary of the Invention

According to a first aspect of the present invention there is provided a method of processing an unfiltered digital image including exposed skin and a corresponding UV filtered digital image, the method comprising the steps of: identifying areas of the unfiltered digital image as containing exposed skin, determining areas of the UV filtered digital image that contain exposed skin by correspondence with the unfiltered digital image; extracting the image characteristics of the exposed skin areas in the UV filtered digital image; and thereby generating an assessment of the effectiveness of sunscreen application to the exposed skin area for output.

A typical standard digital camera (such as those fitted to a typical smartphone) will be sensitive to light down to the lower end of the visible waveband (400nm) and some light in the near-UV band say down to -380nm. Most sunscreens, whilst adapted to be primarily active to absorb/reflect light in the UVA band may have some capacity to absorb or reflect light toward or beyond the upper end of the UVA band (say up to -420nm). The present invention thus allows assessment of sunscreen application to exposed skin by detecting the difference in light absorption/reflection of exposed skin within a small overlap wavelength band comprising the lower wavelength sensitivity range of a standard digital camera and the upper end of the light absorption range of typical sunscreens. This overlap band is typically approximately 380-420nm, although this may vary slightly depending on the specific camera and sunscreen respectively.

The unfiltered digital image and the UV filtered image may be obtained by the same digital camera. In some embodiments, the unfiltered and UV filtered images may be captured by separate, adjacently positioned, digital cameras. Such digital cameras may be provided on separate devices or integrated into a common device. Typically, each digital camera is a standard visible light digital camera. Examples of such digital cameras include those fitted to common consumer smartphones. The digital camera may be a dedicated digital camera or may be a digital camera integrated into another device such as a smartphone, laptop computer, desktop computer, tablet computer or the like.

The method may be carried out by any suitable processing unit. Typically, the processing unit may be integrated with the digital camera and/or the device in which the digital camera is integrated. In some embodiments, some or all features of the method may be controlled by a local software application. In some embodiments, the processor may be operable to communicate with a remote device in order to carry out the method. In alternative embodiments, the processor may be on a remote device in communication with the device into which the digital camera is integrated.

The effectiveness assessment may be output on a display unit. The display unit may be a dedicated display unit or may be a display unit integrated with the digital camera or integrated into the same device as the digital camera.

The UV filtered image may exclude data from light wavelengths greater than a threshold value. The threshold value may be around, say, 420nm.

The UV filtered image may be generated from the unfiltered image by digital filtering. In such embodiments, a digital filter may be applied to the unfiltered image to exclude data from light wavelengths greater than the threshold value, the digital filtering may be carried out by the processor or by a dedicated digital filtering unit. In other embodiments, the UV filtered image may be generated by applying a physical UV filter to a digital camera lens.

In one embodiment, the effectiveness assessment may comprise combining the extracted image characteristics with the unfiltered image to generate an augmented image for output In such embodiments, the augmented image may be generated by overlaying the extracted image characteristics over the exposed skin areas in the unfiltered image. In such embodiments, the extracted image characteristics may be overlaid in a distinctive colour, pattern, tone or the like. This can enable ready identification of the relative application effectiveness of sunscreen to exposed skin. This can facilitate targeted reapplication (and reassessment using the same method) as appropriate to improve sunscreen application effectiveness.

Extracting the image characteristics of the exposed skin areas may include the step of determining the intensity of radiation recorded in the exposed skin areas of the UV filtered image. The determined intensity data can be used to infer the amount of UV radiation reflected or absorbed by the exposed skin. In some embodiments, the determined intensity data may be processed as part of the effectiveness assessment.

In some embodiments, the augmented image may be generated by overlaying determined intensity data on the unfiltered image. In further embodiments, the augmented image may be generated by overlaying processed determined intensity data on the unfiltered image. In this manner, areas of exposed skin with determined intensity data corresponding to effective and/or ineffective application of sunscreen can be readily highlighted on the display. This can even better facilitate targeted reapplication (and reassessment using the same method) as appropriate to improve sunscreen application effectiveness.

In some such embodiments, the processing may comprise the step of identifying relatively low and/or relatively intensity values. Values may be identified as relatively low and/or relatively high based on a statistical analysis and/or based on deviation from a mean value. Variation in the relative intensity values can indicate variation in UV absorption/reflection and hence variation in sunscreen application. In such cases, the processing may include classifying effectiveness in respect of the proportion of determined intensity values identified as relatively high and/or relatively low.

In some such embodiments, the processing may comprise the step of comparing the determined intensity values to one or more reference intensity values. In such embodiments, the effectiveness assessment may include classifying the determined intensity values as exceeding or not exceeding the refence values. Variation in the determined intensity values can indicate variation in UV absorption/reflection and hence variation in sunscreen application. In such cases, the processing may include classifying effectiveness in respect of the proportion of determined intensity values as exceeding or not exceeding the refence values.

In some embodiments, the processing may be varied in response to camera properties and/or sunscreen properties. For examples, the intensity values identified as relatively low and/or relatively high and/or the reference intensity values may vary for different sunscreens and/or for different cameras. This can take account of different camera performance and different sunscreen formulations. Value variations may be stored in a look up table. The look up table may be provided local to the processor or may be stored remotely and accessed by the processor over a suitable data network.

In some such embodiments, the method may include the step of identifying the sunscreen applied and/or the digital camera. The sunscreen may be identified by capturing and processing an image of the sunscreen packaging. This may be particularly advantageous where the sunscreen packaging comprises a machine-readable code such as a QR code. Additionally or alternatively, the device into which the camera is integrated may be provided with a user operable interface enabling user selection of a particular sunscreen In this context, sunscreen formulations may vary by brand, by performance mode (reflection or absorption) and by protection factor. Protection factor is typically measured on the sun protection factor (SPF) scale wherein for an SPF factor of n, 1/n of the incident UV radiation is absorbed by the skin rather than being absorbed by or reflected away by the sunscreen.

The skilled man will appreciate that in some such embodiments the processing may comprise a combination of identifying relatively low and/or relatively intensity values and comparing the determined intensity values to one or more reference intensity values.

In embodiments, where the processing includes classification of effectiveness, the output effectiveness assessment may comprise said classification. Such classifications may be a banded classification such as "effectively applied-, -partially effectively applied-or the like In other such embodiments, the output effectiveness assessment may comprise a numerical value such as a fractional or percentage effectiveness score.

According to a second aspect of the present invention there is provided a method of assessing sunscreen application to skin, the method comprising the steps of: capturing corresponding unfiltered and UV filtered digital images including exposed skin using a standard digital camera; and processing the unfiltered and UV filtered digital images according to the method of the first aspect of the present invention The method of the second aspect of the present invention may incorporate any or all aspects of the first aspect of the present invention, as desired or as appropriate.

According to a third aspect of the present invention there is provided a device for assessing sunscreen application to skin, the device comprising: one or more digital cameras, said camera or cameras operable to capture corresponding unfiltered and UV filtered digital images of exposed skin; a processing unit operable to: identify areas of the unfiltered digital image as containing exposed skin; determine areas of the UV filtered digital image that contain exposed skin by correspondence with the unfiltered digital image; extract image characteristics of the exposed skin areas in the UV filtered digital image, and thereby generate an assessment of the effectiveness of sunscreen application to the exposed skin area; and an output unit for outputting the generated effectiveness assessment.

The device of the third aspect of the present invention may incorporate any or all features of the first or second aspects of the invention as desired or as appropriate.

Detailed Description of the Invention

In order that the invention may be more clearly understood one or more embodiments thereof will now be described, by way of example only, with reference to 10 the accompanying drawings, of which: Figure 1 is a schamtic illustration of the capture of images for use in the method of the present invention, Figure 2 is a series of schematic illustrations of (a) an unfiltered image, (b) a UV filtered image, and (c) an augmented image according to the present invention, Figure 3 shows schematic block diagrams of alternative embodiments of the invention; and Figure 4 shows schematic flow diagrams of the implementation of the method A method of assessing sunscreen application to exposed skin of a person 1 according to the present invention, requires the capture of a digital image of the person using a device 10 (such as a smartphone) incorporating a digital camera 11. As is shown in figure 1, the person 1 has exposed skin on their arms 2, legs 3 and head 4. The remainder of the person's skin is covered by a t-shirt 5, shorts 6 or shoes 7.

A standard digital camera (such as those fitted to a typical smartphone) will be sensitive to light down to the lower end of the visible waveband (400nm) and some light in the near-UV band say down to -380nm Most sunscreens, whilst adapted to be primarily active to absorb/reflect light in the UVA band may have some capacity to absorb or reflect light toward or beyond the upper end of the UVA band (say up to -420nm). Accordingly, by combining a standard unfiltered digital image with a corresponding UV filtered digital image (excluding incident light with wavelength exceeding -420nm) it is possible to assess the effectiveness of sunscreen application.

Referring now to figure 2 the method is illustrated schematically. Firstly, figure 2a shows an unfiltered visible light image A of person I captured by the digital camera 11 of device 10. The person 1 has applied sunscreen to exposed skin on their arms 2 and legs 3 but has not applied sunscreen to the exposed skin of their head 4. The areas of exposed skin can be identified by suitable processing of the image A. A corresponding UV filtered image B is shown in figure 2b. Whilst the UV filtered image B will, of course, appear different to the unfiltered image A, the areas of the arms 2 and legs 3 with sunscreen applied have a contrasting appearance to the different appearance in the UV filtered image B due to the applied sunscreen. This is illustrated by the shading shown in figure 2b. Also visible in figure 2b are areas of the arms 2 and legs 3 which are not shaded. This indicates an inadequate application of sunscreen or a failure to apply sunscreen to these areas.

As the UV filtered image B corresponds to the unfiltered image A, the equivalent areas of the UV filtered image B can be determined to comprise exposed skin. Image characteristics of these areas UV filtered image B, such as intensity values can be extracted and combined with the unfiltered image A to generates an augmented image C for output, as shown in figure 2c. In this particular example, the image characteristics extracted from UV filtered image B are overlaid on the unfiltered image A. The augmented image C can then be displayed on a display unit 13 of the device 10. The person 1 (or other persons) can then view the augmented image C and readily identify areas of omitted or inadequate sunscreen application.

Turning now to figure 3a, the key components for implementing the invention are described, specifically, a digital camera 11, a processing unit 12 and a display unit 13. As is shown in figure 3a, typically these components are each integrated into a single device 10, such as a smart phone or the like. In the event that the device 10 is not capable of any of the required processing steps using internal resources, the skilled man will appreciate that the device may be operable to communicate data to a remote sewer or the like through a suitable data connection. Such communicated data may be processed remotely and returned to the device post processing via said data connection.

In the embodiment of figure 3a, the camera 11 is operable to capture an unfiltered image A of the person 1. The processing unit 12 is operable to process the unfiltered image A to identify areas of exposed skin. The processing unit 12 is further operable to digitally filter the unfiltered image A to generate the UV filtered image B. The processing unit 12 can then further process the UV filtered image B to extract image characteristics from the areas of the UV filtered image B corresponding to exposed skin. Subsequently, the processing unit 12 can use the extracted image characteristics to generate the augmented image C for output via the display unit 13.

In an alternative embodiment shown in figure 3b, a moveable physical filter 14 is provided in front of the camera 11. In such embodiments, the camera 11 may be operable to capture an unfiltered image A of the person 1 when the UV filter 14 is not in place and to capture a subsequent UV filtered image B of the person I once the UV filter 14 is in place. In such an embodiment, the processing unit 12 need not apply digital filtering to the unfiltered image A, but the method may be otherwise implemented as above.

In a further alternative shown in figure 3c, if a device 10 has two adjacent cameras 11, 15 one camera 11 can be used to capture the unfiltered image A and the second camera 15 may be fitted with a UV filter 14 and used to simultaneously capture the UV filtered image B. In such an embodiment, the processing unit 12 need not apply digital filtering to the unfiltered image A but the method may be otherwise implemented as above.

The skilled man will appreciate that whilst the filter 14 illustrated in figures 3b and 3c is external to the device 10 and internal filter 14 could be provided in certain circumstances.

Turing now to figure 4a, a flow chart is shown illustrating a basic implementation of the method in more detail.

At step 101, an infiltered image A is captured using digital camera 11 At step 102 a UV filtered image B is acquired either by digital filtering of the unfiltered image A or by capturing a UV filtered image by way of a camera 11, 15 provided with a UV filter 14. At step 103, exposed skin areas in unfiltered image A are identified, by processing unit 12. This may be achieved by use of a suitable skin identification algorithm. Such algorithms may be operable to identify potential exposed skin areas by reference to known limb shapes and/or a range of possible skin colours.

At step 104, image characteristics are extracted from areas in the UV filtered image B corresponding to exposed skin areas in the unfiltered image A. At step 105, the extracted image characteristics are combined with the unfiltered image A to generate an augmented image C. The augmented mage C may subsequently be output on display unit 13 at step 106.

The step 104 of extracting image characteristics may include determining the intensity of radiation recorded in the exposed skin areas of the UV filtered image B This intensity data can be overlaid on the unfiltered image A at step 105. Optionally, the overlaid data may be given a false colour or tone for ready identification.

The resultant augmented image can be used to infer the amount of UV radiation reflected or absorbed by the exposed skin and hence the likely effectiveness of sunscreen application to the exposed skin By reviewing the augmented image output at step 106, a person can This can facilitate targeted sunscreen reapplication (and reassessment using the same method) as appropriate to improve sunscreen application effectiveness.

In some embodiments, the determined intensity data may be processed as part of the effectiveness assessment. Possible examples of such optional processing are shown in the flow chart of figure 4b.

At step 201 the intensity of radiation in the exposed skin areas of the UV filtered image B is determined. Optionally, at step 202, the method includes identifying the sunscreen applied and/or the digital camera model. This can allow the processing to account for different camera and sunscreen properties.

In some examples, details of the camera can be input by a person using an interface provided on device 10. In other examples, the processor 12 may be operable to directly identify the camera based on identity codes and/or device model. Where details of the camera properties are not stored locally, the processor 12 may look up necessary details from a remote server or device via a data connection In some examples, details of the sunscreen can be input by a person using an interface provided on device 10. This might be achieved by entry of the brand and SPF factor into a free text or structured data interface provided on the device 10. In other examples, the digital camera 11 may be used to capture an image of the sunscreen packaging The sunscreen can then be identified by processing the captured image for instance to recognise text or logos associated with the identity of the sunscreen or to recognise a QR (or other machine readable code) identifying the sunscreen. Where details of the sunscreen properties are not stored locally, the processor 12 may look up necessary details from a remote server or device via a data connection.

At step 203 relatively low and/or relatively intensity values within the determined intensity vales are identified. Values may be identified as relatively low and/or relatively high based on a statistical analysis and/or based on deviation from a mean value. Variation in the relative intensity values can indicate variation in UV absorption/reflection and hence variation in sunscreen application.

The cut off for identifying relatively high/relatively low values may vary depending on the camera properties and/or the sunscreen properties. In particular, this may depend on the SPF value of the sunscreen. A sunscreen with a relatively high SPF value might be expected to have provide a greater contrast in UV intensity between skin where the sunscreen is applied and skin where the sunscreen is not applied than a sunscreen with a relatively low SPF value.

Whether relatively high values, relatively low values or both are of interest may depend on the mode of operation of the sunscreen. For instance, where a sunscreen is reflective of UV radiation, it is of more interest to identify relatively low intensity values on exposed skin areas whereas for a sunscreen that is intended to be effective by absorbing UV radiation, it is of more interest to identify relatively low intensity values on exposed skin areas.

Additionally, or in place of step 203, the processing at step 204 comprises the step of comparing the determined intensity values to one or more reference intensity values. Typically, this step would also include classifying the determined intensity values as exceeding or not exceeding the refence values. Variation in the determined intensity values can indicate variation in UV absorption/reflection and hence variation Ii in sunscreen application, in particular, UV intensity exceeding or not exceeding particular thresholds may be indicative of effective or ineffective application in a particular case. As discussed in relation to step 203, the threshold values could be varied depending on the camera properties or especially on the sunscreen proprieties.

For instance, absolute values of threshold may be varied as SPF varies, since this would vary the amount of UV radiation reflected/absorbed. Additionally, the mode of operation (absorption/reflection) may determine whether exceeding or not exceeding a threshold value is considered of interest.

Where either/both step 203 or step 204 is carried out, the processing can optionally include classifying the effectiveness of sunscreen application at step 205.

This step could include classifying overall effectiveness in respect of the proportion of determined intensity values identified as relatively high and/or relatively low and/or the proportion of determined intensity values as exceeding or not exceeding the refence values. The overall classified effectiveness may be output for display at step 206. This can be displayed in addition to or in place of the augmented image. Such classifications may be a banded classification such as "effectively applied", "partially effectively applied" or the like.

In other examples, classification of effectiveness may be carried out individually for each part of the exposed skin areas. In such cases, determined intensity values of interest (i.e. those that are relatively high/low and/or exceed/do not exceed particular thresholds) may be identified as effective and/or ineffective as appropriate. In such cases, information identifying or highlighting effective or ineffective application may be overlaid on the unfiltered image A to form the augmented image C. The one or more embodiments are described above by way of example only.

Many variations are possible without departing from the scope of protection afforded by the appended claims.

Claims (1)

1. CLAIMSA method of processing an unfiltered digital image including exposed skin and a corresponding UV filtered digital image, the method comprising the steps of: identifying areas of the unfiltered digital image as containing exposed skin; determining areas of the UV filtered digital image that contain exposed skin by correspondence with the unfiltered digital image; extracting the image characteristics of the exposed skin areas in the UV filtered digital image; and thereby generating an assessment of the effectiveness of sunscreen application to the exposed skin area for output 2. A method as claimed in claim 1 wherein the unfiltered digital image and the UV filtered image are obtained by the same digital camera.A method as claimed in claim 1 or claim 2 wherein the digital camera is a digital camera integrated into another device.A method as claimed in any preceding claim wherein the method is carried out by a processing unit integrated with the digital camera and/or the device in which the digital camera is integrated A method as claimed in any preceding claim wherein the effectiveness assessment is output on a display unit 6. A method as claimed in claim 5 wherein the display unit is a display unit integrated with the digital camera or integrated into the same device as the digital camera.A method as claimed in any preceding claim wherein the UV filtered image excludes data from light wavelengths greater than a threshold value.8. A method as claimed in any preceding claim wherein the UV filtered image is generated from the unfiltered image by digital filtering.A method as claimed in any preceding claim wherein the effectiveness assessment comprises combining the extracted image characteristics with the unfiltered image to generate an augmented image for output.10. A method as claimed in claim 9 wherein the augmented image is generated by overlaying the extracted image characteristics over the exposed skin areas in the unfiltered image.H. A method as claimed in claim 10 wherein the extracted image characteristics are overlaid in a distinctive colour, pattern or tone 12. A method as claimed in claim any preceding claim wherein extracting the image characteristics of the exposed skin areas includes the step of determining the intensity of radiation recorded in the exposed skin areas of the UV filtered image.13. A method as claimed in claim 12 wherein the determined intensity data is processed as part of the effectiveness assessment.14. A method as claimed in claim 13 wherein the augmented image is generated by overlaying determined intensity data on the unfiltered image or by overlaying processed determined intensity data on the unfiltered image.IS 15. A method as claimed in claim 13 or claim 14 wherein the processing comprises the step of identifying relatively low and/or relatively intensity values.16. A method as claimed in any one of claims 13 to 15 wherein the processing comprises the step of comparing the determined intensity values to one or more reference intensity values.17. A method as claimed in any one of claims 13 to 16 wherein the processing is varied in response to camera properties and/or sunscreen properties.18. A method as claimed in any one of claims 13 to 17 wherein the processing includes classification of the effectiveness assessment and output of the classification of the effectiveness assessment.19. A method of assessing sunscreen application to skin, the method comprising the steps of: capturing corresponding unfiltered and UV filtered digital images including exposed skin using a standard digital camera; and processing the unfiltered and UV filtered digital images according to any one of claims Ito 18.20. A device for assessing sunscreen application to skin, the device comprising: one or more digital cameras, said camera or cameras operable to capture corresponding unfiltered and UV filtered digital images of exposed skin; a processing unit operable to: identify areas of the unfiltered digital image as containing exposed skin; determine areas of the UV filtered digital image that contain exposed skin by correspondence with the unfiltered digital image; extract image characteristics of the exposed skin areas in the UV filtered digital image; and thereby generate an assessment of the effectiveness of sunscreen application to the exposed skin area; and an output unit for outputting the generated effectiveness assessment.21. A device as claimed in claim 20 wherein the unfiltered digital image and the UV filtered image are obtained by the same digital camera 22 A device as claimed in claim 20 or claim 21 wherein the output unit is a display unit 23 A device as claimed in claim 22 wherein the display unit is a display unit integrated with the digital camera or integrated into the same device as the digital camera 24. A device as claimed in any one of claims 20 to 23 wherein the UV filtered image excludes data from light wavelengths greater than a threshold value 25. A device as claimed in any one of claims 20 to 24 operable to implement the method of any one of claims 1 to 19