Examining visible skin conditions

Abstract

A method of, and apparatus for, examining a visible skin condition by placing the housing 101 of a device at the location of a region of skin containing a visible skin condition 102, imaging the regio

Description

The present invention relates to an examination apparatus and in particular to an apparatus for examining visible skin conditions. The present invention also relates to an examination method and in particular to a method of examining visible skin conditions. It is known to examine skin conditions visually, which may be achieved directly, possibly via a lens or indirectly by means of a camera. Suggestions have been made to the effect that a video camera included within a mobile phone could be deployed to achieve this. However, problems arise in terms of reliability and repeatability. Proposals have been made for examining visible skin conditions using electric fields, However, problems arise if electrodes generating these electric fields are in contact with a skin condition itself. According to a first aspect of the present invention there is provided a method of examining a visible skin condition, comprising the steps of: locating a housing at a region of a visible skin condition; capturing image data of the skin over said region; generating electric fields that penetrate the skin over said region, such that an application of the apparatus produces both image-related signals and electric field related signals for the same skin condition; calculating the surface area of the visible skin condition from the image data produced by said capturing step; determining an indication of the volume of the visible skin condition from the electric field related signals; and processing said calculated surface area in combination with said determined indication of volume to assess the depth of skin penetration. In an embodiment, said generating step is performed by an electric field generating device that comprises a first dielectric substrate having a hole having a first radius; said capturing step is performed by a camera; and the visible skin condition is viewed through said hole. The image data may be captured by the camera substantially at the same time as electric fields are generated by the electric field generating device. In an embodiment, the image data from said capturing step is displayed on a visual display device. The displayed image data may be enhanced in response to the electric field data. The step of changing colour properties of the visible skin condition shown in the image data could be enhanced in response to the electric field data and, in particular, by an extent related to the assessed depth of penetration. According to a second aspect of the present invention, there is provided an apparatus for examining a visible skin condition, comprising: a housing for location at a region of a visible skin condition; an image capturing device for capturing image data of the skin over said region; an electric field generating device for generating electric fields that penetrate the skin over said region, such that an application of the apparatus produces both image-related signals and electric field related signals for the same skin condition; and a processor configured to: calculate the surface area of the visible skin condition from image data captured by said image capturing device; determine an indication of the volume of the visible skin condition from the electric field related signals generated by said electric field generating device; and process said calculated surface area in combination with said determined indication of volume to assess the depth of skin penetration. The invention will now be described by way of example only with reference to the accompanying drawings, of which: Figure 1 shows an apparatus for examining visible skin conditions; Figure 2 shows the apparatus of Figure 1 obtaining test data; Figure 3 shows the apparatus of Figure 1 in an inverted position; Figure 4 shows the apparatus of Figure 1 in a cradle; Figure 5 details the dielectric substrate identified in Figure 3; Figure 6 shows an internal subassembly for the apparatus identified in Figure 1; Figure 7 shows procedures performed by a microcontroller contained within the apparatus; Figure 8 details procedures for producing electric field data as identified in Figure 7; Figure 9 shows procedures for calculating and saving data identified in Figure 8; Figure 10 illustrates the production of output samples identified in Figure 9; Figure 11 details procedures for identifying and storing information identified in Figure 9; Figure 12 illustrates the population of a database table; Figure 13 shows the examining apparatus connected to a data processing system; Figure 14 shows procedures performed by the data processing system identified in Figure 13; Figure 15 details procedures for processing the received data identified in Figure 14; Figure 16 illustrates the processing of images; Figure 17 shows an image of a first visible skin condition; Figure 18 shows an image of a second visible skin condition Figure 19 shows a procedure for processing image and electric field related data; and Figure 20 shows a cross section of the apparatus of Figure 3. Figure 1 An apparatus for examining visible skin conditions is shown in Figure 1 and comprises a housing 101 locatable at a region of the skin under examination; an example 102 of a skin condition is illustrated. The housing contains a camera for capturing image data of the skin over the region of the skin condition. In addition, an electric field generating device is configured to generate electric fields that penetrate the skin over the region, such that an application of the apparatus produces both image related signals and electric field related signals for the same skin condition. In an embodiment, reference image data is produced and reference electric field data is also produced by placing the apparatus firstly at a position of healthy skin, as shown in Figure 1. Thus, while located as illustrated in Figure 1, a camera captures reference image data and the electric field generating device produces reference signals from which electric field reference data is produced. In an alternative embodiment, reference data is obtained by deploying the apparatus upon a reference proxy device having known optical and electrical properties. As an example, the reference proxy device may comprise a receptacle containing an oil, such as olive oil. Figure 2 As shown in Figure 2, after obtaining reference data, as described with respect to Figure 1, the apparatus is moved to the position of the visible skin condition 102 to produce test image data and test electric field data. To initiate a procedure, an operative applies pressure to a manual activation button 201 to generate reference data. Thereafter, after moving the apparatus to a location substantially similar to that shown in Figure 2, a second activation of this button 201 results in the generation of the test data. In alternative embodiments, alternative measures may be taken to initiate this activation and activation could be initiated by a connected computer. In the embodiment shown in Figure 2, the apparatus includes a socket 202 for interfacing with a cradle, as described with reference to Figure 4, which may in turn be connected to a data processing system, such as a laptop computer and a connection of this type will be described with reference to Figure 13. In the embodiment of Figure 2, the camera is configured to capture image data substantially at the same time as the electric field generating device generates electric fields. In practice, these operations are likely to be performed sequentially but a complete cycle may be completed within a time interval of only a few seconds. Thus, from the perspective of an operative, the electric field data and the image data are captured substantially at the same time, such that the captured data is derived from the apparatus held in a fixed location relative to the region of the skin being examined or the region of the skin providing reference data. Figure 3 The housing 101 is shown inverted in Figure 3, exposing a first dielectric substrate 301 with a hole 302 having a first radius. The dielectric substrate may take the form of a board of a substantially conventional type onto which circuits may be printed or etched. Scanning electrodes, including a first scanning electrode 311 and a second scanning electrode 312, are circumferentially evenly displaced on a first planar surface of the dielectric substrate 301 at a second radius around the hole 302. In this way, it is possible for the camera to view the skin condition through the hole 302. This portion of the housing, which comes into contact with a subject’s skin, may be covered by a transparent replaceable cap that is also configured to permit the transmission of electric fields. In the embodiment shown in Figure 3, the apparatus has a total of sixteen scanning electrodes, although alternative embodiments could have fewer or more scanning electrodes. In an embodiment, each scanning electrode 311 to 316 may be energised as a transmitter or monitored as a receiver. Thus, in an embodiment, a full scanning cycle may consist of energising each of the available scanning electrodes which are sequentially selected. In an embodiment, upon selecting a scanning electrode as a transmitter, it may be energised a total of fifteen times with a different scanning electrode being selected as the receiver for each energisation. In the embodiment of Figure 3, each scanning electrode is configured exclusively to be energised, and thus act as a transmitter, or to be configured as a receiver. In the embodiment of Figure 3, the functionality of the electrodes is fixed; with eight of the scanning electrodes acting as transmitters alternating with the remaining eight electrodes acting as receivers. In the example shown in Figure 3, electrode 331 is being energised sequentially eight times. Electrode 312 acts as a receiver and electrode 332 acts as a receiver on the next energisation cycle. Thus, eight energisations of the same electrode are made sequentially with each of the available eight receiving electrodes. Energisations of this type produce electric fields that extend away from the plane of the dielectric substrate 301. In the embodiment of Figure 3, respective electrical conductors for each of the scanning electrodes 311 to 326 are configured to pass through the first dielectric substrate to a second planer surface. The embodiment of Figure 3 also includes circumferentially and substantially evenly displaced secondary electrodes 341, 342 etc. In the embodiment of Figure 3, a total of eight secondary electrodes (341 - 348) are provided at a third radius that is larger than the second radius. In an alternative embodiment, the number of secondary electrodes present is the same as the number of scanning electrodes and each secondary electrode may be radially displaced from a respective scanning electrode. The secondary electrodes 341 to 348 do not perform scanning operations as such and the scanning operations are performed exclusively by the scanning electrodes. However, appropriate connections to the secondary electrodes can influence the resulting electric fields and as such can increase the size of the dataset. Figure 4 After performing the operations described with respect to Figure 1 and Figure 2, the apparatus is returned to a cradle 401. In an embodiment, the socket 202 engages a plug extending from the cradle 401 and the cradle 401 may be connected to a data processing system by means of a USB (or similar) socket 402. A USB connection from socket 402 may be used to perform data transfer from the apparatus to a data processing system. In an alternative embodiment, data transfer from the apparatus to the data processing system occurs wirelessly, thereby enhancing an operative’s ability to move around a subject and position the apparatus appropriately. Figure 5 The dielectric substrate 301 is shown in Figure 5, with the scanning electrodes 311 to 316 and the secondary electrodes 341 to 348 mounted thereon. A camera 501 is visible through the hole 302 and is surrounded by a cylindrical shroud 502. The camera 501 may produce individual still images in response to being triggered. Alternatively, the camera may be a video camera producing a stream of video images which may be viewed on an appropriate external device while the apparatus is being placed in position. Activation of the manual activation button 201 then results in a particular image being selected followed by the electric fields being generated to produce electric field data. In an alternative embodiment, it is also possible for video material to be recorded. Figure 6 An internal subassembly for the apparatus is shown in Figure 6, with the first dielectric substrate 301 inverted. The first dielectric substrate 301 may take the form of a conventional circuit board which, as shown in Figure 6, is attached to a second circuit board 602 which is in turn attached to a third circuit board 603. Electronic components are supported on the second circuit board 602 and a third circuit board 603 for implementing procedures described with reference to Figure 7 to Figure 12. In an embodiment, these electronic components include an inertial module such as that produced by iNEMO and made available under the commercial designation LSM6 DS016IS. This provides a three-axis accelerometer and a three-axis gyroscope with an intelligent sensor processing unit. In this way, it is possible for a data processing system to receive data indicating the position and orientation of the apparatus when in use as described with reference to Figure 1 and Figure 2. The underside of camera 501 is also shown in Figure 6, to which is attached a heatsink 604. In an embodiment, the camera is widely available under the commercial designation OV5640 and is capable of providing image data at a definition from 320x240 pixels up to 2592x1944 pixels in an eight-bit or ten-bit RAW RGB output format. An autofocusing capability is also available but the necessity for this is mitigated on the basis that the distance between the camera and the subject remains substantially the same; given that activation only takes place after the apparatus has been appropriately located. Figure 7 Procedures performed by a microcontroller contained within the apparatus described with reference to Figure 6, are detailed in Figure 7. After being switched on at step 701, the apparatus is placed in a reference position, as described with reference to Figure 1. The processor is then interrupted by activation of the manual activation button 201 at step 702. In an alternative embodiment, it is possible for a first thread to be responsible for generating image data and a second thread to be responsible for generating the electric field data. In the embodiment shown in Figure 7, the reference image data is produced at step 703 and the reference electric field data is then produced at step 704. In an embodiment, a light-emitting diode present within the apparatus may be activated to indicate to an operative that the reference data has been collected. The operative would then be invited to relocate the apparatus to collect the test data, as described with reference to Figure 2. Meanwhile, in an embodiment, the reference image data and the reference electric field data are uploaded to a data processing system as described with reference to Figure 13. Thus, the light-emitting diode may be illuminated after the upload process has been completed and the procedure then anticipates a further activation of the manual activation button 201 at step 706 At step 707, test image data is produced which is then followed, at step 708, by the production of test electric field data. These procedures are substantially similar to procedures 703 and 704 respectively. Thus, again, the test image data and the test electric field data are uploaded to the data processing system at step 709. In the embodiment of Figure 7, a reset operation is performed at step 710 in anticipation of a further interrupt signal being received. The processor therefore enters a wait state at step 711. At step 712, a question is asked as to whether the system is to power down and if answered in the affirmative, the apparatus switches off at step 713 to conserve battery power. Alternatively, if the question asked at step 712 is answered in the negative, the processor awaits the next activation interrupt at step 702. Figure 8 As described with reference to Figure 7, procedure 704 for producing the electric field reference data and procedure 708 for producing the electric field test data are substantially similar; and procedure 708 is detailed in Figure 8. In an embodiment, scanning electrodes may be selected for energisation to optimise the quality of the collected data. Similarly, appropriate scanning electrodes may be monitored. In the embodiment illustrated in Figure 8, all of the transmitter electrodes are selected as an energised electrode and for each selected energised electrode, all of the remaining receiver electrodes are sequentially selected as monitored electrodes. The selection of these capacitively coupled electrodes may occur in any order but to facilitate the creation of appropriate instructions, the electrodes are selected sequentially in numerical order in the embodiment shown in Figure 8. In the embodiment shown in Figure 8, on a first iteration, the first scanning electrode 311 is selected at step 801 and the second scanning electrode 312 is selected at step 802. At step 803, data is collected for this capacitively coupled pair as described with reference to Figure 9. At step 804, a question is asked as to whether another electrode is present to be monitored and on the first iteration this question will be answered in the affirmative resulting in the selection of the next receiver electrode. Thus, this procedure is repeated until all of the remaining receiver electrodes have been selected, resulting in the question asked at step 804 being answered in the negative. At step 805, a question is asked as to whether another transmitter electrode is present to be energised such that, on this first iteration, the next transmitter electrode will be selected at step 801 and repeated iterations of step 802 will result in all of the remaining receiver electrodes being sequentially selected as electrodes to be monitored. Thus, the process will continue until all of the transmitter electrodes have been selected at step 801 and the question asked at step 805 will be answered in the negative. Figure 9 Procedure 803 for calculating and saving data derived from the electric field signals are detailed in Figure 9. At step 901, one or more of the secondary electrodes 341 to 348 are grounded. At step 902 the scanning electrode selected at step 801 is energised and at step 903 the scanning electrode selected at step 802 is monitored and sampled. The data collected, as described with reference to Figure 10, is then identified and stored at step 904. At step 905, the secondary electrodes 341 to 348 are allowed to float and the selected electrodes are again coupled by energising the electrode selected at step 801 and monitoring the electrode selected at step 802. Thus, each selected pair are capacitively coupled twice in accordance with this embodiment. Again, at step 908, the data is identified and stored. In an embodiment, each energising pulse lasts for a duration of ten microseconds and individual pulses are separated by a duration of ninety microseconds. During each cycle, one hundred samples are taken, thereby requiring a sample rate of five megahertz. In an alternative embodiment, fewer samples are taken and in alternative embodiments more samples may be taken. In an embodiment, fifty samples are taken. An analogue to digital converter, which in an embodiment forms part of the microcontroller, converts each sample into a twelve-bit representation and as a result of this, each energising pulse generates a significant amount of data. However, the processor is fast enough to allow a significant amount of processing to take place during the sample period. Thus, by comparing samples, it is possible to identify a peak value and the regular intervals between samples allows the time at which this peak value occurred to be determined. Thus, each sample point is made up of data that defines a voltage level at a particular time. The resulting data is saved initially at step 904 and then again at step 908. This raw data is processed to produce a smaller volume of output data that, in an embodiment, is transferred to a data processing system as described with reference to Figure 13. In an alternative embodiment, the raw data is transmitted to the data processing system and the procedures identified above, for reducing the data volume, are performed on the data processing system. Figure 10 The production of output samples at step 903 (or at step 907) is illustrated in Figure 10. In the graph shown in Figure 10, output voltage 1001 is plotted against time 1002. The sampling operation creates data points, such as data point 1003 and data point 1004. As is known in the art, it is also possible to fit a curve 1005 to the real data points, such that other values on this curve may be calculated through a process of interpolation. From this, it is possible to identify a peak value 1006. Having calculated the peak value 1006, it is then possible to identify points at which a portion of this peak value has been achieved. Thus, from the large volume of raw data, it is possible to calculate a much more limited volume of data (information) which conveys what is required in terms of a rate of charge, a peak and a rate of discharge. Furthermore, it is known that the absolute peak value and the rate of discharge are directly related to the conductivity and permittivity of the tissue being examined. Figure 11 Procedures 904 and 908 for identifying and storing information (the data that will be uploaded to the data processing system) are shown in Figure 11. At step 1101, the peak value 1006 is identified and this peak information 1007 is stored at step 1102. At step 1103, a value is calculated that represents sixty-three percent of the peak value 1007. At step 1104, data is stored, consisting of a first data point 1021 and a second data point 1022 at which the curve 1005 passes through the sixty-three percent value. At step 1105, a value is calculated that represents fifty percent of the peak value 1007. A first data point 1031 and a second data point 1032 are identified where the curve 1005 crosses this fifty percent level. At step 1107, a value is calculated that represents thirty-seven percent of the peak value 1007. Again, at step 1108, a first data point 1041 is stored, along with a second data point 1042, showing where the curve 1005 crosses these values. Figure 12 The refined data (or information) calculated at steps 1102, 1104, 1106 and 1108 are stored in a database and a representation of this database is illustrated in Figure 12. k data table 1201 is constructed for the reference data and a similar data table 1202 is constructed for the test data. In a first column 1211, the electrode being energised is recorded and in a second column 1212 the electrode being monitored is recorded. For each of these combinations, a third column 1213 records whether secondary electrodes were grounded or allowed to float. The resulting information is then stored in a fourth column 1214 In this embodiment, the information (data for transmission to the data processing system) represents the first peak value 1221. The information then represents the two positions for thirty-seven percent of the peak value 1222, the two positions for fifty percent of the peak value 1223 and the two positions for sixty-three percent of the peak value 1224. After fully populating the database table of Figure 12, the resulting information consists of a relatively small volume compared to the totality of raw data generated through the scanning and sampling operations. In an embodiment, this information is transferred to a data processing system, as described with reference to Figure 13, for subsequent processing. The overall objective is to identify the nature of the tissue under consideration. In particular, when scanning visible skin conditions, the overall objective is to give an indication as to whether the skin condition is considered benign or whether the skin condition is considered malignant and therefore requires further attention. As is clear from the table shown in Figure 12, similar combinations exist for both the reference stage 704 and the test stage 708. Thus, specific similar information entries may be directly compared to determine the extent to which they differ. In an embodiment, a larger difference may indicate that the skin under test has characteristics that differ significantly from healthy skin; thereby prompting further investigation. Figure 13 The examining apparatus 101 is shown in Figure 13, connected to a data processing system 1301. The data processing system 1301 also communicates with a remote data analysis system 1302 via the Internet 1303. In the embodiment described with reference to Figure 6, the apparatus includes a signal processor for processing electric field signals produced by the electric field generating device, which are in turn influenced by the electrical properties of the penetrated tissue, to produce electric field data as described with reference to Figure 7 to Figure 12. Thus, in an embodiment, the data stored in the database described with reference to Figure 12 is transmitted to the data processing system 1301 either wirelessly or via a connected cable 1304. The cable 1304 may also be used to recharge batteries contained within the apparatus 101. In an embodiment, data communication occurs wirelessly from the examining apparatus to the data processing system 1305 without the need for the examining apparatus to be returned to a cradle. In this way, it is possible for the examining apparatus 101 to be displaced by a significant distance away from the data processing system; possibly being located in a different room, while allowing the data to be collected by the data processing system. In this alternative embodiment, the examining apparatus is returned to a cradle for charging purposes only and cable 1304 may be connected to a conventional power supply. In addition to transferring the electric field data, image data is also transmitted from the apparatus 101 to the data processing system 1301. The data processing system 1301 provides a visual display 1305 for displaying the received image data. The camera 501 may be a video camera and may continually supply video images to the data processing system, which can be viewed on the visual display 1305. After positioning the apparatus, as described with reference to Figure 1 and Figure 2, and upon activation of the manual activation button 201, a high definition still image may be viewed on the visual display 1305. In addition, a display may also be provided to show a graphical representation of the received electric field data. Furthermore, in an embodiment, it is possible for a visual image derived from the image data to be enhanced in response to the electric field data. This enhancement may be used to provide a local indication of the extent to which the skin condition may be considered malignant and therefore in need of further investigation. The electric field data and the image data may also be conveyed to the remote data analysis system 1302 In an embodiment, a machine learning exercise may be performed to analyse image data and electric field data in combination with independent assessments; such that it is possible to provide an additional indication of a need for medical intervention. Furthermore, over a period of time, as more data is collected, enhancements may be made to the machine learning process and the output from the machine learning process may be combined with local assessments made by operatives. This combined data may then allow enhancements to be made to the procedures performed by the data processing system 1305 and the remote data analysis system 1302. In an alternative embodiment, data collected by the examining apparatus 101 may be conveyed, possibly via a data processing system, directly to the remote data analysis system. This allows sophisticated analysis to take place, possibly derived from a machine learning process, and in turn an indication may be returned from the remote data analysis system to the examining apparatus to indicate whether the skin condition under consideration may be considered as benign or malignant. In in an embodiment, appropriately coloured light emitting diodes may be included on the examination apparatus, resulting in the examining apparatus, for example, being illuminated in a blue colour if the area under consideration is considered to be benign and illuminated in a red colour if the area under consideration is considered to be malignant and thereby requiring further attention. Further colours may be included to indicate gradations between these two extremes. Alternatively, it is possible for a display device to be included as part of the examining apparatus itself. Figure 14 Procedures performed by the data processing system 1301 are illustrated in Figure 14. At step 1401, reference image data is received whereafter, at step 1402, reference electric field data is received. The selected images are stored in the examination apparatus 101 and the electric field data is read from the database table described with reference to Figure 12. Thereafter, at step 1403, test image data is received and at step 1404 test electric field data is received. At step 1405 the image test data is displayed on the visual display 1305. The test image data is captured in response to operation of the manual activation button 201 as described with reference to Figure 2. At step 1406 the data that has been received at steps 1401 to 1404 are processed and the processed data is displayed at step 1407. At step 1408 a question is asked as to whether the data is to be uploaded for data analysis and when answered in the affirmative, the data is uploaded to the remote data analysis system 1302. This allows an operative to perform the exercise several times upon the same subject until data has been collected that is considered optimum by the operative. Thus, a graphical user interface displayed on the visual display 1305 may invite an operative to upload the data for data analysis or invite the operative to repeat the examination process. At step 1410 the local data that has been uploaded to the remote system, at step 1409, is stored locally on the data processing system 1301 whereafter, at step 1411, the system is reset for the next testing operation to be performed. At step 1412 a question is asked as to whether the process is to close and the process ends if the question is answered in the affirmative. Alternatively, control returns to step 1401 in anticipation of receiving further data. Figure 15 An example of procedure 1406 for processing the received data is shown in Figure 15. However, it should be appreciated that many manipulations of this data may be performed to facilitate local assessments and to optimise the quality of the data that is uploaded to the remote data analysis system. In this example, the image data is keyed at step 1501 to separate the image of the visible skin condition from background skin. This allows the area of concern to be specified at step 1502. At step 1503 the electric field data is normalised, which may involve subtracting the reference data from the test data. Again, alternative mathematical manipulations may be performed at this stage with a view to optimising the effectiveness of the electric field data. Fundamentally, the purpose of these procedures is to identify the existence of problematic conditions. Thus, the electric field data may suggest that the area of skin which shows a visible skin condition does not represent an area of skin that may be considered problematic, which may in turn suggest that no further action is required. Alternatively, the electric field test data may be substantially different from the electric field reference data and this in turn may indicate that the skin condition is malignant and requires further attention. Consequently, in this embodiment, the area of concern in the image data is modified at step 1504 and an enhanced display of this modified data is produced at step 1505. Figure 16 The results of the procedure described with reference to Figure 15 are illustrated in Figure 16. Images are displayed on the visual display 1305, either sequentially, as shown in Figure 16, or in combination. A first image 1601 represents the image test data displayed at step 1405. This shows the particular skin condition of interest 1602 surrounded by healthy skin 1603. The raw image data consists of eight or ten bits representing light intensities for red, green and blue. These are illustrated in a first histogram 1611, depicting a level for red 1612, a level for green 1613 and a level for blue 1614. These levels represent the colour of the skin condition 1602 and different levels would be represented for the surrounding skin 1603. These differences allow the area representing the skin condition 1602 to be distinguished over values representing the background skin 1603. Following known keying techniques, this allows pixels representing the skin condition to be separated from the background pixels, such that the image may depict the skin condition against a plain white background as shown in a second image 1622. In the second image 1622, the skin condition image 1602 appears as before but this time it is shown against a white background 1623. When represented in red-green-blue (RGB) colour space, pixel values representing the skin condition 1602 remain the same as illustrated in chart 1611. As is known in the art, manipulations may be performed within this RGB colour space. In this embodiment, the intention is to enhance pixel values which show the skin condition to an extent determined by the analysis of the electric field data. In this example, individual pixel values are transformed from red-green-blue colour space to luminance, hue and saturation colour space (usually identified as YHS respectively). A second histogram 1624 shows the same colour as that represented in chart 1611 but in YHS colour space. Furthermore, in this embodiment, modifications are made at step 1504 by adjusting the luminance values and the saturation values in response to the electric field data. For the purposes of this example, it is assumed that the electric field test data differs significantly from the electric field reference data. This creates a significant difference signal and this is used to make an appropriate adjustment. Thus, as shown in a third histogram 1625, the luminance of the image has been significantly increased and the saturation of the image has also been significantly increased. The hue remains unchanged such that the colour of the displayed region 1626 substantially retains its original colour. Referring to the first histogram 1611, the colour is substantially red and therefore appears red both in the original image and in the processed image. However, based upon the electric field difference values, the brightness of the image 1626 is increased and the saturation of the image is also increased. Adjustments to the saturation will make the red colour appear more red and less pink for example. An operative can clearly compare the modified image with the original image and from this make an assessment as to whether further intervention is required. Furthermore, additional prompts may be provided by the data processing system itself and a recommendation may also be made to the extent that the data should be sent to the remote data analysis system. In alternative embodiments, different modifications to the image data could be made. For example, the hue of the image could be changed making the area of the visible skin condition appear in a very unsightly green colour, for example, when a malignant condition is suspected. Alternatively, the luminance value could be modified periodically to create a flashing or throbbing image; again, bringing the condition to the attention of an operative. The system therefore presents a method of examining a visible skin condition in which a housing is located at a region of a visible skin condition. Image data is captured of the skin over the region and electric fields are generated that penetrate the skin over the region, such that an application of the apparatus produces both image related signals and electric field related signals for the same skin condition. In an embodiment, a visual image is created that is derived from the image data and this image may be enhanced in response to the electric field data. In an embodiment, the test image data is compared against reference image data to identify an area of concern within the region, as shown in image 1622. Furthermore, a keying operation may be performed to isolate the area of concern in the image data and colour properties of the area of concern may be changed in response to the electric field data. Figure 17 A visible skin condition 1701 as shown in Figure 17. The apparatus described with reference to Figure 2 has been located over this visible skin condition and a captured image is bounded by circle a 1702. For each deployment of the apparatus, the size of the visible image remains substantially constant and the number of pixels populated also remains constant. Consequently, the overall area of the image contained within the circle 1702 is known and may be represented in terms of the number of pixels present. Following a keying operation, as described with reference to Figure 16, it is possible for the area of the visible skin condition 1701 to be determined, as a subset of the available pixels, such that the area may be converted into conventional units or represented as a percentage of the overall area contained within circle 1702. For the purposes of this illustration, it may be assumed that the visible skin condition 1701 is relatively large and, to a clinician, could be seen as problematic. The visible skin condition may be identified as a mole for example and the clinician would wish to know the extent to which the mole has penetrated the skin, representing the possibility of the undesirable material reaching a blood supply. For the purposes of this illustration, a cross-section of the visible skin condition 1701 is shown at 1703. The cross-section illustrates an epidermis 1704 and a dermis 1705. In many situations, moles of this type would be considered problematic if they have, or if they possibly could, penetrate the dermis 1705. However, in this example, the depth of the visible skin condition 1701, as illustrated by a first arrow 1706, is relatively shallow and has not entered the dermis 1705. However, the captured image data does not provide this information and a clinician may be prompted to organise a biopsy. However, in the environment of Figure 17, this would be unnecessary and the clinician would be better informed if it were possible to obtain information indicating the depth of penetration without incurring a surgical procedure. Figure 18 An image of a second visible skin condition 1801 is shown in Figure 18. The overall area of the totality of the image is substantially the same as that described with reference to Figure 17 and is again identified by circle 1702. Again, the area of the second visible skin condition 1801, which again may be identified as a mole, is much smaller than the area of the first visible skin condition 1701. Thus, when presented only with the image data, a clinician may be tempted to conclude that the first visible skin condition 1701 appears more problematic than the second skin condition 1801. For the purposes of illustration, a cross-section of the second skin condition is shown at 1802, with similar representations for an epidermis 1803 and a dermis 1804. In this example, the second visible skin condition 1801 has penetrated through the epidermis 1803 and has also penetrated through most of the dermis 1804; such that there is now a significant risk of the undesirable material reaching blood capillaries below the dermis 1804. Thus, although from a visual inspection, the first visible skin condition 1701 appears more problematic than the second visible skin condition 1801, in reality, due to the depth of penetration, the second visible skin condition 1801 is actually more problematic and would be assessed, following biopsy, as requiring surgical intervention. Figure 19 A further embodiment for step 1406 of processing the received data, as described with reference to Figure 14, is illustrated in Figure 19. In an embodiment, steps described with reference to Figure 15 may also be incorporated. At step 1901 the surface area of the visible skin condition is calculated. This makes use of the captured image data as described with reference to Figure 17. At step 1902, the volume of the visible skin condition is determined from the electric field related data. Thereafter, at step 1903, the calculated surface area is processed in combination with the determined indication of volume to assess the depth of skin penetration. As illustrated in Figure 3, the generated electric fields extend from the plane of the apparatus in three-dimensional space and thereby penetrate the skin. In an embodiment, this degree of penetration is such that it extends below the dermis 1705 / 1804. As previously described, data is obtained by generating reference data which is then compared with the test data. The inventor has appreciated that the resulting electric field related signals represent, in the test data, values which vary with respect to the amount or volume of undesirable material present. Thus, the electric field data does not exclusively vary with respect to the viewable area of the skin condition but varies with respect to the totality of material present in the three-dimensional region comprising the epidermis 1803 and the dermis 1804. For the purposes of this illustration, it may be assumed that the volume of the undesirable material identified at 1701 is substantially similar to the volume of undesirable material identified at 1801. In many practical implementations, it is unlikely that these assessments will be perfectly linear but in alternative embodiments, modifications may be made to the geometry of the apparatus to improve linearity, processing exercises may be performed to compensate for non-linear effects or reliance may be made upon a trained machine learning procedure. However, the realisation made by the inventor is to the effect that an indication of depth 1905 may be obtained by dividing the determined volume 1906 by the calculated surface area 1907. Following this procedure, the first visible skin condition 1703 producers a determined volume that is very similar to that of the second visible skin condition 1802. However, the calculated area for the first visible skin condition 1701 is much larger than the calculated area for the second visible skin condition 1801, therefore the assessment of depth 1905 will be significantly deeper for the second visible skin condition 1801. Consequently, in a clinical environment, an operative would receive information to the effect that the second visible skin condition 1801 is actually likely to be more problematic than the first visible skin condition 1701. In an embodiment, deploying procedures substantially similar to those described with reference to Figure 15 and Figure 16, modifications to the perceived colour of the visible skin conditions could be changed with reference to the depth assessment 1905. Thus, for the purposes of illustration, it may be assumed that when viewing the captured image data, the first visible skin condition 1701 appears to have a colour that is substantially similar to the second visible skin condition 1801. However, following the procedure described with reference to Figure 19, colour modifications may be made, as described with reference to Figure 16, such that, when viewed, greater 5 modifications are made to the colour of the second visible skin condition 1801 compared to the first visible skin condition 1701. Figure 20 A cross-section of the apparatus of Figure 3 is shown in Figure 20. The housing 101 supports the first dielectric substrate 301 and the camera 501. 10 The visible skin condition is viewed through the hole 302 in the first dielectric substrate 301. Scanning electrodes on the first dielectric substrate sequentially produce electric fields including a first electric field 2001. This extends vertically from the housing 101 to penetrate the visible skin condition. Subsequently, a second electric field is generated that also penetrates the 15 visible skin condition but with a greater degree of penetration. Similarly, a third electric field is generated with an even greater degree of skin penetration.

Claims

1. A method of examining a visible skin condition, comprising the steps of:locating a housing at a region of a visible skin condition;capturing image data of the skin over said region;generating electric fields that penetrate the skin over said region, such that an application of the apparatus produces both image-related signals and electric field related signals for the same skin condition;calculating the surface area of the visible skin condition from the image data produced by said capturing step;determining an indication of the volume of the visible skin condition from the electric field related signals; andprocessing said calculated surface area in combination with said determined indication of volume to assess the depth of skin penetration.

2. The method of claim 1, wherein:said generating step is performed by an electric field generating device that comprises a first dielectric substrate having a hole having a first radius;said capturing step is performed by a camera; andthe visible skin condition is viewed by said camera through said hole.

3. The method of claim 2, wherein image data is captured by the camera substantially at the same time as electric fields are generated by the electric field generating device.

4. The method of any of claims 1 to 3, wherein said calculating step is performed by pixel counting.

5. The method of any of claims 1 to 4, further comprising the step of locating the housing over an area of healthy skin to obtain reference signalsfor comparison against test signals.

6. The method of any of claims 1 to 5, wherein the image data from said capturing step is displayed on a visual display device.

7. The method of claim 6, further comprising the step of enhancing the image data in response to the electric field data.

8. The method of claim 7, comprising the step of changing colour properties of the visible skin condition shown in the image data in response to the electric field data.

9. The method of claim 7, comprising the step of changing the image data by an extent related to the assessed depth of penetration.

10. The method of any of claims 1 to 9, further comprising the step of analysing the image data and the electric field data to produce output data following a machine learning exercise.

11. An apparatus for examining a visible skin condition, comprising: a housing for location at a region of a visible skin condition;an image capturing device for capturing image data of the skin over said region;an electric field generating device for generating electric fields that penetrate the skin over said region, such that an application of the apparatus produces both image-related signals and electric field related signals for the same skin condition; anda processor configured to:calculate the surface area of the visible skin condition from image data captured by said image capturing device;determine an indication of the volume of the visible skin condition fromthe electric field related signals generated by said electric field generating device; andprocess said calculated surface area in combination with said determined indication of volume to assess the depth of skin penetration.

12. The apparatus of claim 11, wherein:said electric field generating device comprises a first dielectric substrate having a hole having a first radius;said capturing step is performed by a camera; andthe visible skin condition is viewed by said camera through said hole.

13. The apparatus of claim 12, wherein a said processor is configured to capture image data at substantially the same time as electric fields are generated by said electric field generating device.

14. The apparatus of any of claims 11 to 13, wherein said processor is configured to calculate surface area by pixel counting.

15. The apparatus of any of claims 11 to 14, configured to be located over an area of healthy skin to obtain reference signals for comparison against test signals.

16. The apparatus of any of claims 11 to 15, comprising a visual display device for displaying captured image data.

17. The apparatus of claim 16, wherein said processor is configured to enhance the image data in response to the electric field data.

18. The apparatus of claim 17, wherein the processor is configured to change colour properties of the visible skin condition shown in the image data in response to the electric field data.

19. The apparatus of claim 17, wherein the processor is configured to change the image data by an extent related to the assessed depth of penetration.

520. The apparatus of any of claims 11 to 19, wherein an external processing system is configured to analyse the image data and the electric field data to populate a machine learning environment.10A

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