A method of reading an optically readable security element using illumination intensity

Abstract

A method of reading an optically readable security element (ORSE) 200 using an image capturing device (ICD) 100 comprises establishing a relative configuration between the ORSE and ICD such that an il

Description

TECHNICAL FIELD The present disclosure relates to a method of reading an optically readable security element, and a related device and system. BACKGROUND Security elements or tags are used to provide security in relation to an object to which they are attached. These security elements provide security in relation to the object by labelling the object. For example, a security element may be encoded with a unique (e.g., randomised) identity that can be extracted from the security element, thereby enabling authentication of the object. However, nefarious actors may attempt to provide a response or signal which imitates or mimics a response or signal provided by a genuine security element (e.g., an area of the security element encoding a unique identity) when the genuine security element is read during a reading operation. This action may be known as “spoofing”. Nefarious actors typically do not have access to information relating to the manner in which the genuine security element is read, and thus the imitated response may have a predetermined form. For example, the provided imitated response may have a form which corresponds with an expected response obtained from a conventional or typical reading operation. Hence, there is a desire to provide a method of reading an optically readable security element wherein the response of the reading operation is dependent on the manner or context in which the reading operation is performed, thereby improving security. Furthermore, and perhaps more generally, it is desirable to increase complexity of imitating the response provided by a genuine security element when read during a reading operation and / or improve accuracy of reading of the security element. SUMMARY It is one aim of the present disclosure, amongst others, to provide a method of reading an optically readable security element which at least partially obviates or mitigates at least some of the disadvantages of the prior art, whether identified herein or elsewhere, or to provide an alternative approach. For instance, it is an aim of embodiments of the invention to provide a method of reading an optically readable security element wherein the response of the reading operation is dependent on the manner in which the reading operation is performed, thereby improving security. Furthermore, it is an aim of embodiments of the invention to increase complexity of spoofing and / or improve accuracy of reading of the security element. According to the present invention there is provided a method of reading an optically readable security element, an image capturing device, and a related system, as set forth in the appended claims. Other features of the invention will be apparent from the dependent claims and the description that follows. According to a first aspect, there is provided a method of reading an optically readable security element, using an image capturing device, the method comprising: establishing a relative configuration between the optically readable security element and the image capturing device, such that an illumination intensity gradient is present across the optically readable security element, whereby different regions of the optically readable security element are illuminated with different illumination intensities; and reading the optically readable security element using the illumination intensity gradient, such that reading of different regions of the optically readable security element is undertaken with different illumination intensities. The method further comprises: determining the relative configuration between the optically readable security element and the image capturing device; during or following reading the optically readable security element, determining a measured response of the optically readable security element to the illumination; and comparing the measured response with an expected response of the optically readable security element to the illumination, the expected response being established based on the determined relative configuration. In one example, determining the relative configuration between the optically readable security element and the image capturing device comprises: determining a map of values which relate to a distance between each different region of the optically readable security element and a light emitting element of the image capturing device. In one example, the map of values is determined based on one or more of: information obtained by reading an engineered component of the optically readable security element; an orientation of the optically readable security element; an optical characteristic of a region of the optically readable security element or a region surrounding the optically readable security element; an output of a three-dimensional mapping process. In one example, the method further comprises: establishing the expected response based on the map of values. In one example, the method further comprises: establishing the expected response based on one or more of: information relating to composition of the optically readable security element; information relating to intensity of illumination of the optically readable security element, from a source of illumination; information relating to environmental conditions; information relating to a condition of the optically readable security element. In one example, the optically readable security element and the image capturing device are relatively configured to provide the illumination intensity gradient. In one example, the regions of the optically readable security element are regions of a second area, the second area comprising an identity. In one example, the method further comprises: during or following reading the optically readable security element, extracting the identity from the optically readable security element, and comparing the extracted identity with identities stored in a database. In one example, establishing the relative configuration between the optically readable security element and the image capturing device comprises: providing the image capturing device in an angled orientation relative to the optically readable security element, or adjusting an angle of orientation of the image capturing device relative to the optically readable security element; providing the optically readable security element in an angled orientation relative to the image capturing device, or adjusting an angle of orientation of the optically readable security element relative to the image capturing device; providing the optically readable security element on a non-planar surface, such that the optically readable security element has a non-planar form; and / or causing the optically readable security element to adopt a non-planar form. In one example, the optically readable security element comprises one or more optical emitters arranged to be read via emission radiation emitted from the one or more optical emitters. In one example, the optically readable security element comprises one or more optical emitters arranged to be excited by excitation radiation, optionally wherein the image capturing device is configured to emit the excitation radiation. In one example, the method comprises capturing an image of the optically readable security element using the illumination intensity gradient, preferably capturing a single image of the optically readable security element using the illumination intensity gradient. According to a second aspect of the present invention, there is provided an image capturing device for reading an optically readable security element, the image capturing device comprising: a reader configured to read the optically readable security element; and a processor configured to: read the optically readable security element using an illumination intensity gradient, such that reading of different regions of the optically readable security element is undertaken with different illumination intensities. In one example, the processor is further configured to: determine the relative configuration between the optically readable security element and the image capturing device; during or following reading the optically readable security element, determine a measured response of the optically readable security element to the illumination; and compare the measured response with an expected response of the optically readable security element to the illumination, the expected response being established based on the determined relative configuration. The image capturing device according to the second aspect may comprise any or all features of the method according to the first aspect, as necessary or as desired. According to a third aspect of the present invention, there is provided a system comprising: an optically readable security element; and an image capturing device according to the second aspect. The system according to the third aspect may comprise any or all features of the method according to the first aspect and / or the image capturing device according to the second aspect, as necessary or as desired. BRIEF DESCRIPTION OF DRAWINGS For a better understanding of the invention, and to show how embodiments of the same may be brought into effect, reference will be made, by way of example only, to the accompanying Figures, in which: Figure 1 shows a flowchart for a method of reading an optically readable security element; Figure 2 shows a first configuration of an optically readable security element being read by an image capturing device; Figure 3 shows a second configuration of an optically readable security element being read by an image capturing device; Figure 4 shows a third configuration of an optically readable security element being read by an image capturing device; Figure 5 shows a flowchart for a method of determining relative configuration; Figure 6 shows an image of an optically readable security element with an area divided into pixels; Figure 7 shows a flowchart for a method of a process of image capture and information acquisition; Figure 8 shows a flowchart relating to fingerprint comparison; Figure 9 shows a flowchart relating to emission comparison; Figure 10 shows a flowchart relating to response of the reading; Figure 11 shows an image capturing device; and Figure 12 shows a system. DETAILED DESCRIPTION The description which follows describes a method of reading an optically readable security element. In summary, as introduced above, it is an aim of embodiments of the invention to provide a method of reading an optically readable security element wherein the response of the reading operation is dependent on the context or manner in which the reading operation is performed, thereby improving security. Furthermore, it is an aim of embodiments of the invention to increase complexity of spoofing and / or improve accuracy of reading of the security element. Figure 1 shows a flowchart for a method of reading an optically readable security element (ORSE). The method of Figure 1 will be best understood in conjunction with Figures 2 to 4, which show an image capturing device 100 (ICD 100) reading an ORSE 200 in a field of view 300 (e.g., in a same image frame) of the ICD 100. The ORSE 200 comprises a first area 210 and a second area 220. The first area 210 may comprise an engineered component, such as a QR code, in which information or data is included. The second area 220 comprises an identity. The identity may be extractable from the second area 220. The identity can be used to authenticate the object to which the ORSE 200 is attached (including authenticating the ORSE 200 itself), advantageously, therefore, providing security in relation to the object. In an example, the first area 210 and second area 220 may be discrete (i.e., separate and distinct) areas. The first and second areas 210, 220 being distinct and spaced apart may, advantageously, facilitate easier distinction and reading (or even manufacturing) thereof. However, any arrangement of the first area 210 and the second area is possible. For instance, the first area 210 and the second area 220 may correspond to adjacent and contiguous areas (e.g., the ORSE 200 may be divided between the first area 210 and the second area 220 along a longitudinal axis) of the ORSE 200 or adjacent and non-contiguous areas (e.g., an equal number of equally sized strips). The first and second areas 210, 220 may partially or completely overlap one another, which, advantageously, may reduce the required space for both or make it harder to copy or replicate one or both areas 210, 220. The method comprises establishing S100 a relative configuration between the ORSE 200 and the ICD 100, such that an illumination intensity gradient is (deliberately and intentionally) present across the ORSE 200, whereby different regions of the ORSE 200 are (deliberately and intentionally) illuminated with different illumination intensities. The method comprises reading S110 the ORSE 200 using the illumination intensity gradient, such that reading of different regions of the ORSE 200 is undertaken with different illumination intensities. The response from different regions to those different illumination intensities will typically be different, or at least dependent on those different illumination intensities. In other words, this may be said to be reading S110 the ORSE 200 “by the image capturing device” or “using the image capturing device”. Advantageously, in this way, the illumination intensity gradient used in the reading of the ORSE 200 leads to a measured ORSE 200 response which is dependent on the relative configuration between the ORSE 200 and the ICD 100. That is, a gradient is not just accidentally or incidentally present. The illumination intensity gradient is deliberately and intentionally used, and is an intrinsic part of the invention. A configuration dependent response is highly advantageous in improving security, as, absent information of the relative configuration, a spoofed response of the ORSE 200 to the illumination is unlikely to correspond with an expected response established based on the relative configuration between the ORSE 200 and the ICD 100. In this way, using the illumination intensity gradient in the reading of the ORSE 200 is highly advantageous in improving security, and increasing complexity of spoofing. Furthermore, by using the illumination intensity gradient, it is possible to avoid, remove and / or limit a need to capture multiple images, or image frames, at different illumination intensities to examine the response of an ORSE to illumination. In this way, by using the illumination intensity gradient, fewer measurements may be required, and the process of reading the ORSE 200 may therefore be both simpler and faster, whilst still ensuring improvements in security, and a high level of security. That is, as will be appreciated from the description herein, the result of multiple intensity measurements may be replaced (or reconstructed) with the use of a single imaging step using an illumination intensity gradient. The step of establishing a relative configuration between the ORSE 200 and the ICD 100 may mean that the ORSE 200 and the ICD 100 are relatively configured such that an illumination intensity gradient is providable across the ORSE 200, or relatively configured to provide the illumination intensity gradient. This may be described as deliberately, or intentionally, establishing the relative configuration so that an illumination intensity gradient is present. This may be achieved in a number of different ways, examples of which will be described in greater detail below. The method comprises determining the relative configuration of the ORSE 200 and the ICD 100. That is, characteristics of said relative configuration, or values defining the configuration, may be determined. For example, a map or set of distances between the ICD 100 and various points on the ORSE 200, and / or information relating to the gradient of the surface ofthe ORSE 200 relative to the ICD 100, may be determined. Determining the relative configuration will be described in greater detail below. During or following reading the ORSE 200, the method comprises determining a measured response of the ORSE 200 to the illumination. The measured response is intended to be the measured response of a genuine (i.e., authentic) ORSE 200 to the illumination. However, nefarious actors may look to provide a measured response (i.e., signal or information) which imitates or mimics that of a genuine ORSE. The method comprises comparing the measured response with an expected response of the ORSE 200 to the illumination, the expected response being established based on the determined relative configuration. In this way, the expected response accounts for the relative configuration, and thus the illumination intensity gradient present, used, or employed during the reading. If the measured response is the measured response of a genuine ORSE 200 (thereby providing a response which is indicative of the relative configuration used during imaging or reading), a correspondence between measured response and expected response may be determined, and it can be determined that the measured response is indeed that of a genuine ORSE 200 (which may be a physical, valid, ORSE 200). The measured response may be accepted as that of a genuine ORSE 200. In contrast, if the measured response is not the measured response of a genuine ORSE 200 (thereby possibly not providing a response which is indicative of the relative configuration used during imaging or reading, or at least not resembling the same configuration used in the establishing the expected response), a correspondence between measured response and expected response may not be determined, and can be determined that the measured response may be the result of an attempt to imitate or mimic a genuine ORSE response. In such a case, the imitated measured response may be determined to have been provided without actually reading a genuine ORSE, and this can be determined due to the lack of correspondence between the measured response and the expected response. The measured response may be rejected. Referring to Figures 2 to 4, relative configurations between the ORSE 200 and the ICD 100 are shown. In each case, the ORSE 200 may be provided on a surface of an object, thereby enabling authentication of the object. The ORSE 200 may be attached, affixed printed, embedded, or otherwise provided on the object. Each relative configuration leads to the desired illumination intensity gradient being present, or provided, across the ORSE 200. Other relative configurations not described here may also be usable, as will be understood by those skilled in the art. The ICD 100 may comprise a light emitting element 130 (e.g., in the form of a light or flash), which provides a source of illumination. It will be appreciated that whilst the relative configuration is said to be between the ORSE 200 and the ICD 100, in a preferred example where illumination is provided by the light emitting element 130, the relative configuration is specifically that of the arrangement between the light emitting element 130 of the ICD 100 and the ORSE 200. Using the light emitting element 130 of the ICD 100 is highly advantageous as it has a known location, or displacement, relative to a reader (e.g., a sensor, such as a camera) of the ICD 100. Furthermore, using the light emitting element 130, the intensity of illumination can be known and controlled. In this way, the relative configuration can be calculated or established more easily. In some examples, described in further detail below, the geometry of the ORSE 200 can be established quicker and / or more easily. The light emitting element 130 can be controlled so that it is the main, or dominant, source of illumination in the field of view of the reader. In some examples, a set of images can be captured whilst using, and also not using, the illumination provided by the light emitting element 130, so that the response induced by the illumination can be inferred from said captured images. In a highly advantageous example, the light emitting element 130 provides a source of excitation radiation. That is, the ICD 100 may be configured to emit the excitation radiation. The excitation radiation is used to excite one or more optical emitters provided on the ORSE 200, preferably at the second area 220, thereby to emit emission radiation. Various optical effects may be exploited, including photoluminescence, fluorescence, reflection, scattering, refraction, or the like, although photoluminescence is preferred. This is because photoluminescence may be far more sensitive to changes in illumination intensity, and / or harder to mimic, and so more secure. The arrangement of the one or more optical emitters may encode the identity. Whilst use of the light emitting element 130 is also preferred, in some examples it may be possible to make use of external (e.g., ambient) lighting to provide the illumination, and thus the illumination intensity gradient. Again, an illumination intensity gradient is beneficial, because this can result in different excitation-emission responses across the ORSE 200. Most preferably, the second area 220 comprises one or more optical emitters arranged to be read via emission radiation emitted therefrom. Relatedly, the one or more optical emitters may be arranged to be excited by excitation radiation. The one or more optical emitters may serve as the component that provides or serves as the unique identity. Advantageously, the ORSE 200 being read via emission emitted therefrom provides a more robust barrier to fraudulent reading, more readily preventing spoofing or copying by, for instance, simply replicating (e.g., by printing) a bar code, QR code or similar. This advantage is particularly true when one or more (e.g., hundreds, thousands or millions or more) of optical emitters are distributed randomly. For instance, this effect may be achieved using quantum dots, flakes of 2D materials, (e.g., small) molecules, atomic defects or vacancies, plasmonic structures or similar. In some examples, emission radiation from the one or more optical emitters may be non-isotropic. That is, certain suitable materials may have non-isotropic emission. In these cases, there may exist a known angular dependence to their emission, which may be independent from their excitation dependence). For example, this may be the case where the material, or emitters thereof, exhibit a strong dipole moment (e.g., emitters or molecules with a preferential deposition orientation), where the material incorporates fluorescent molecules, and / or due to optical effects associated with the deposition of emitters. In the latter example, if emitters are included in a transparent thin (e.g., order of a few microns) film, then as the depth of the film varies with angle so too will the measured emission (e.g., reflection, or diffraction) strength. A further, highly advantageous, feature of the invention may be realised due to this non-isotropic emission, including by virtue of thin-film effects. By non-isotropic emission, a single ORSE 200 may provide multiple unique identities (e.g., a different response depending on the angle of illumination). In other words, a plurality of unique identities may correspond with a single ORSE 200, or the identities “registered against” the ORSE 200. Each unique identity may be derived from capturing the image, or images, of the ORSE 200 at different orientations (e.g.., angle of illumination) thereby to provide different illumination intensity gradients. In this way, it is possible to generate multiple measured responses and expected responses (as described in greater detail below), and multiple comparisons can be performed, thereby further enhancing security. Referring to Figure 2, the ORSE 200 is shown in a vertical orientation. The ORSE 200 is flat (i.e., planar). This may be a result of the ORSE 200 being provided on a flat surface of an object. Whilst the ORSE 200 is shown in a vertical orientation, the ORSE 200 may be provided in a different orientation. The ICD 100 is oriented at an angle 0 to the vertical axis. That is, the ICD 100 is provided in an angled orientation relative to the ORSE 200. In some examples, the angle of orientation of the ICD 100 may be adjusted relative to the ORSE 200 to provide the desired relative configuration. When the ICD 100 is used to illuminate the ORSE 200, an illumination intensity gradient is present across the ORSE 200 due to the relative angle between the device 100 and ORSE 200. It will be appreciated that the angle 0 may be provided by a user of the device 100 angling, or tilting, the device 100. When the ICD 100 is used to illuminate the ORSE 200, an illumination intensity gradient is present across the ORSE 200 due to the varying distance, or varying separation, between the ORSE 200 and the light emitting element 130 of the ICD 100. That is, in the illustrated example, regions toward an upper edge of the ORSE 200 may be illuminated with a relatively lower illumination intensity, as the upper edge of the ORSE 200 is farther away from the light emitting element 130 of the ICD 100. Referring to Figure 3, the ORSE 200 is shown in an angled orientation. A perspective view is shown in Figure 3A, and a side view is shown in Figure 3B. The ORSE 200 is flat (i.e., planar). This may be a result of the ORSE 200 being provided on a flat surface of an object. The ORSE 200 is oriented at an angle 9 to the vertical axis. That is, the ORSE 200 is provided in an angled orientation relative to the ICD 100. In some examples, the angle of orientation of the ORSE 200 may be adjusted relative to the ICD 100 to provide the desired relative configuration. When the image capturing device 100 is used to illuminate the ORSE 200, an illumination intensity gradient is present across the ORSE 200 due to the relative angle between the device 100 and ORSE 200. It will be appreciated that the angle 9 may be provided by providing the ORSE 200 on an angled object surface and / or a user of the device 100 angling, or tilting, the device 100. That is, the example of Figure 3 may simply be an alternative view of Figure 2, with the reference frame of device 100 being used to define the vertical axis. When the ICD 100 is used to illuminate the ORSE 200, an illumination intensity gradient is present across the ORSE 200 due to the varying distance, or varying separation, between the ORSE 200 and the light emitting element 130 of the ICD 100. That is, in the illustrated example, regions toward an upper edge of the ORSE 200 may be illuminated with a relatively lower illumination intensity, as the upper edge of the ORSE 200 is farther away from the light emitting element 130 of the ICD 100. Referring to Figure 4, the ORSE 200 is shown having a non-planar form. In particular, the ORSE 200 is shown having a curved form. A perspective view is shown in Figure 4A, and a plan view is shown in Figure 4B. The non-planar (e.g., curved) form of the ORSE 200 may be a result of the ORSE 200 being provided on a non-planar (e.g., curved) surface of an object. Additionally or alternatively, the ORSE 200 may be caused to adopt a non-planar (e.g., curved) form, for example by manipulation of the object on which the ORSE 200 is provided. The ORSE 200 may have an angle of arc 9. When the ICD 100 is used to illuminate the ORSE 200, an illumination intensity gradient is present across the ORSE 200 due to the varying distance, or varying separation, between the ORSE 200 and the ICD 100. That is, in the illustrated example, regions toward the lateral edges of the ORSE 200 are at a greater distance from the light emitting element 130 of the ICD 100 than regions toward the centre of the ORSE 200. As a result, the regions toward the lateral edges of the ORSE 200 may be illuminated with a relatively lower illumination intensity. Figure 5 shows a flowchart for a method for use in determining the relative configuration between the ORSE 200 and the ICD 100. The method is also for use in generating a transformed, or corrected, image. At step S510, an image of the ORSE 200 is captured using the ICD 100. The image of the ORSE 200 is captured using the illumination intensity gradient. That is, the image of the ORSE 200 is captured using the ICD 100 with the light emitting element 130 thereof in operation. Preferably, a single image of the ORSE 200 is captured using the illumination intensity gradient. Single image capture is made possible by using the illumination intensity gradient. In this way, in contrast with prior art approaches, a need for multiple images, or image frames, utilising different flash intensities, is obviated. The method (i.e., the overall method of verification / validation) is made simpler and / or faster, which ensuring high level of security. Whilst a single image using the illumination intensity gradient is described, it will be appreciated that this does not exclude the possibility of capturing one or more images of the ORSE 200 without operation of the light emitting element 130, which may provide a reference image with which a comparison can be made in order to infer or establish the result of the illumination intensity gradient on the response (e.g., emission) of the ORSE 200. At step S512 - S518, the orientation of the ORSE 200 is calculated or established. This may be known as calculating or establishing the “geometry” of the ORSE 200. Each of steps S512 - S518 may be performed independently, and may be performed exclusively. Advantageously, this may facilitate a rapid calculation of the geometry of the ORSE 200. Alternatively, more than one of steps S512 - S518 may be performed in combination, to advantageously improve accuracy of the calculating or establishing of the geometry and / or to be used as a validation. Information from the ICD 100 may also be used in calculating or establishing the orientation of the ORSE 200, for example information from an accelerometer or gyroscope (or other orientation sensor) of the ICD 100, enabling the determination of orientation of the ICD 100. At step S512, the first area 210 is read. The first area 210 may be or comprise an engineered component. The engineered component may be a QR code, or other codified feature. The reading of the first area 210 allows the ICD 100 to obtain (e.g., access) information about the applied geometry of the ORSE 200. For example, the ICD 100 may read the engineered component, and use that reading to obtain information (e.g., information stored locally or remotely) about the geometry of the ORSE 200, thereby to establish the orientation of the ORSE 200. In an example relating to Figure 3, the ICD 100 may read the engineered component, and use that reading to establish that the ORSE 200 is oriented on the object at an angle 6 to the vertical axis. At step S514, the first area 210 is read. The first area 210 may be or comprise an engineered component, or may include a different feature of the ORSE 200. The projection of the first area 210 in the field of view 300 of the ICD 100 may be used to obtain information about the applied geometry of the ORSE 200. In obtaining said information, the applied geometry of the ORSE 200 may be determined. For example, the applied geometry may be determined by considering the shaping of the first area 210. In an example relating to Figure 3, the ICD 100 may identify an engineered component having a trapezoidal shape, and establish that the ORSE 200 is oriented on the object at an angle 6 to the vertical axis. At step S516, an optical characteristic of the ORSE 200 and / or a surrounding or bordering region may be used to determine the geometry of the ORSE 200. That is, the ICD 100 may determine geometry of the ORSE 200 based on variation in an optical characteristic (e.g., light intensity) of the ORSE 200 and / or a region surrounding or bordering the ORSE 200. At step S518, a three-dimensional mapping process may be performed to calculate the geometry of the ORSE 200. The three-dimensional mapping process may be performed by a three-dimensional mapping system. At step S520, the accessed, calculated and / or determined geometry of the ORSE 200 is used to generate a map of values which relate to the distance between each different region of the ORSE 200 and the light emitting element of the ICD 100. The map may be referred to as a “separation map”. The separation map may provide information about such distances for each pixel of the image of the ORSE 200. An optional further step may comprise generating a corrected image of the ORSE 200. Generating a corrected image may comprise using the separation map to transform the image of the ORSE 200 captured using the ICD 100 into a planar representation of the ORSE 200. As above, the separation map provides information about the distance between the ORSE 200 and the ICD 100 for different regions of the ORSE 200. Using such information, emission intensity from different regions, pixels or sub pixels of the image of the ORSE 200 with known separations from the ICD 100 can be measured and compared with expected values. Alternatively or additionally, the reading of the first area 210 may allow the ICD 100 to determine what illumination intensity gradient is to be applied, or what relative configuration between the ICD 100 and the ORSE is to be established. Referring to Figure 6, an example image of the ORSE 200 is shown with the second area 220 divided into pixels. The image of the ORSE 200 shown in Figure 6 is a corrected, or transformed, into a planar representation. Pixels 610, 620 are indicated. Based on the separation map, for pixel 610, a respective measured intensity can be established to correspond with a first distance determined from the separation map. Similarly, for pixel 620, a respective measured intensity can be established to correspond with a second distance determined from the separation map. The intensities can be compared with expected values, as will be described in greater detail below. If the comparison indicates a level of correspondence of the measured intensity with an expected intensity within a threshold, the reading of the ORSE 200 may be approved. However, if the comparison indicates a level of correspondence outside of the threshold, the reading of the ORSE 200 may be rejected. Reading S110 of the ORSE 200 using the illumination intensity gradient will be described in greater detail with reference to Figures 7 to 10. Referring to Figure 7, a flowchart detailing the process of image capture and information acquisition will be described. At step S710, the ICD 100 may prompt or instruct a user of the device 100 to capture an image of the ORSE 200. At step S720, the ICD 100 may prompt the user to adjust or maintain a relative configuration between the ORSE 200 and ICD 100. For example, this may be performed in order to establish a relative configuration as described above in relation to Figures 2 and 3. Furthermore, it may be desired for a relative configuration to be established where a relative angle is present between the ORSE 200 and ICD 100, for example as described in relation to Figures 2 and 3. This ensures that an illumination intensity gradient is present, or may also enable additional images to be captured for validation of results. The user may be guided or even forced to establish the configuration. For example, this might be achieved by displaying a verification target (e.g. a border or alignment markings) on a viewfinder of the ICD 100. This could be shaped so that, in order to fit or match the ORSE 200, the relative configuration is achieved. For example, a trapezoidal verification target (as compared to a square or rectangular target) may guide or force the user to tilt or angle the ICD 100 or ORSE 200 with respect to one another, to establish the configuration, and the required gradient. Alternatively or additionally, the user may not even be aware that a gradient is being used or established. For example, even if a target is used, and even if a target changes from one form to another (e.g. to change the gradient to another gradient), the user may not know why. One or more different gradients could even be established or used during relative movement between the ICD 100 or ORSE 200, for example when taking one or more images or even a video of the ORSE 200. Again, this might be largely invisible to the user, in that the ICD 100 may be establishing or using the illumination gradients without the user seeing or knowing that this is happening. At step S730, the light emitting element 130 of the ICD 100 may be controlled to emit light toward the ORSE 200 thereby to provide an illumination intensity gradient. The amount, direction, duration and / or other characteristics of the emitted light may be monitored and stored by the ICD 100. A processor of the ICD 100 may perform said monitoring, and a memory of the ICD 100 may perform said storing. The light may be visible light, which might assist the user in performing an identity check. Alternatively, the light may not be visible (e.g. UV) so that the ICD 100 might use the illumination gradients without the user seeing or knowing that this is happening. At step S740, an image of the ORSE 200 is captured by the ICD 100. At step S750, the geometry of the ORSE 200 is obtained, accessed, calculated and / or determined, as described above in relation to Figure 5. At step S760, a corrected (e.g., transformed) image of the ORSE 200 may be generated by the ICD 100, as described above in relation to Figure 5. At step S770, the identity may be extracted from the ORSE 200, specifically from the second area 220 of the ORSE 200. This may be known as generating the “fingerprint” of the ORSE 200. In examples, the identity may be extracted from the ORSE 200 during or following reading of the ORSE 200. In an example, the fingerprint may relate to the arrangement or location (e.g., randomised location) of constituent parts of the second area 220. Importantly, the fingerprint may be independent of the intensity of illumination used in the reading. This contrasts with the “emission map”, as described below, which is dependent on the illumination intensity gradient. At step S780, the relative configuration between the ORSE 200 and ICD 100 is determined. This is performed as described above in relation to Figure 5. In particular, a separation map is generated. The separation map provides information which relates to a distance between each different region of the ORSE 200 and the light emitting element 130 of the ICD 100. In more detail, the separation map provides information which relates to the distance between different region of the ORSE 200 and the light emitting element 130 of the ICD 100 as represented by a corresponding pixel in the captured image. Said information may comprise a map of values, i.e., distance values. At step S790, an emission map is generated. The emission map provides information relating to intensity of emission from different regions of the second area 220. As described above, regions of the second area 220 which are illuminated with a higher intensity (such as those regions of the second area 220 which are at a lesser distance from the light emitting element 130 of the ICD 100) may emit a higher intensity of emission radiation. Similarly, regions of the second area 220 which are illuminated with a lower intensity (such as those regions of the second area 220 which are at a greater distance from the light emitting element 130 of the ICD 100) may emit a lower intensity of emission radiation. As mentioned above, the emission is preferably photoluminescence from optical emitters of the second area 220. However, and again as mentioned above, other optical effects may be exploited or used in the reading. In this regard, the emission map may otherwise be referred to as an “intensity map”. Referring to Figure 8, a flowchart relating to fingerprint comparison will be described. At step S810, the fingerprint generated at step S770 is provided to a remote server, or is compared against a local database. The local database may be encrypted. At step S820, the information (or part thereof) encoded in the engineered component of the first area 210 may be sent to the remote server, or used to find a local record. At step S830, at the remote server, or locally, the fingerprint is checked for similarity to a known record. That is, the extracted identity is compared with identities stored in a database, which may be a local database and / or remote database. If the fingerprint corresponds with the known record at a level at or above a threshold, a valid signature response is returned. Conversely, if the fingerprint fails to correspond with the known record at the level at or above the threshold, a valid signature response is not returned, and the reading may be rejected. Referring to Figure 9, a flowchart relating to emission (or intensity) comparison will be described. At step S910, the emission map (or intensity map) generated at step S790 and the separation map generated at step S780 are transmitted to the remote server or are processed locally. Where the emission map and separation map are transmitted to the remote server, the transmitted information may be encrypted for transmission, thereby ensuring security. At step S920, expected values of the emission map (or intensity map) are established, determined, or generated. The expected values of the emission map may be based on the separation map, that is, may be based on the map of values of distance between the ORSE 200 and the ICD 100. It will be appreciated that where it is determined that a region of the second area (e.g., pixel 610) is at a relatively greater distance from the light emitting element 130 of the ICD 100, a lower intensity is to be expected at that region, and a lower expected value is thereby calculated. The expected value may further account for composition of the ORSE 200, intensity of illumination of the ORSE 200 by the source of illumination (e.g., the light emitting element 130), one or more environmental conditions during the imaging (e.g., ambient lighting conditions), and / or a condition of the ORSE 200 (e.g., the type of ORSE 200, object on which the ORSE 200 is provided, and / or the age of the ORSE 200, where the responsiveness of the ORSE 200 to illumination may degrade over time). Considering one or more of these factors in establishing the expected response is highly advantageous in producing expected values that are accurate for the conditions in which the ORSE 200 is read, and the condition of the ORSE 200, enabling an accurate comparison to be made, and ultimately improving the comparison described in relation to step S930. The expected emission values map may provide information relating to expected emission values for a part or whole of the second area 220. Using a part of the second area 220 may be advantageous in increasing speed of the reading and validation. For example, the part of the second area 220 may be a strip of the second area 220 across which an illumination intensity gradient is expected. At step S930, the emission map (or intensity map) generated at step S790 and the expected values of the emission map generated at step S920 (which may be an expected emission values map) are compared. If the emission map corresponds with the expected emission value map at a level at or above a threshold, a valid signature response is returned, and the reading may be accepted. Conversely, if the emission map fails to correspond with the expected emission value map at a level at or above the threshold, a valid signature response is not returned, and the reading may be rejected. It will be appreciated that if the emission map corresponds with the expected emission value map at a level at or above the threshold, it can be established that the reading of the ORSE 200 is likely to correspond with reading of a genuine ORSE 200, as the emission map and expected emission value map both account for the illumination intensity gradient used in the reading. This leads to a valid signature response being returned, and the reading may be accepted. Conversely, if the emission map fails to correspond with the expected emission value map at a level at or above the threshold, it can be establish that the reading of the ORSE 200 is unlikely to correspond with reading of a genuine ORSE 200, and may instead be a spoofed reading of an ORSE, as only the expected emission value map accounts for the illumination intensity gradient. This leads to a valid signature response not being returned, and the reading may be rejected. Advantageously, in this manner, attempted spoofing can be identified and prevented, and security in relation to the object is improved. Referring to Figure 10, a flowchart relating to response of the reading will be described. At step S1010, if a valid signature response is returned from step S830 and a valid signature response is returned from step S930, a valid measurement result is returned. Otherwise, a failure in the reading may be reported, and the reading may be rejected. A repeat of the reading may be requested, instructed, or prompted by the ICD 100. Figure 11 shows the image capturing device (ICD) 100 in more detail. The ICD 100 may be a terminal device, such as a smartphone. The ICD 100 may be configured to provide a source of illumination, for example to emit excitation radiation to excite the one or more optical emitters of the ORSE 200 (e.g., from an electromagnetic radiation source, such as a flash or LED). By being configured to emit excitation radiation, the ICD 100, advantageously, facilitates the aforementioned robust security. Further, emitting the excitation radiation from the ICD 100, advantageously, allows convenient control of excitation of the one or more optical emitters. The source of illumination may be a UV LED, which advantageously can excite visible fluorescence without reflected light being measured. As shown in Figure 11, the ICD 100 comprises a reader 110 and a processor 120. The reading S110 of the ORSE 200 is performed by the reader 110, which could include or be a sensor. The processor is configured to perform any of the operations described herein, as desired or as appropriate. In particular examples, the processor is configured to read the ORSE 200 using the illumination intensity gradient; determine the relative configuration between the ORSE 200 and the ICD 100; determine a measured response; establish an expected response; compare the measured response with an expected response; extract the identity; and / or any other operation described herein. The processor 120 may be configured to perform the aforementioned steps or actions locally (i.e., at the ICD 100) or externally (e.g., at a server). The processor 120 may be dedicated hardware or existing hardware specifically configured to extract to perform the method. Figure 12 shows a system comprising the ICD 100, the ORSE 200 and a data store 400. The data store 400 may be used to store information about the first area 210 and / or second area 220. For example, the data store may store information linking the engineered component of the first area 210 with an ORSE 200 of a particular applied geometry. In other words, information about the second area 220 may be stored in the data store 400. Storing the information about the second area 220 in the data store 400, advantageously, introduces an extra layer of security and / or enables use of a less sophisticated, for instance, engineered component. The data store 400 may be an external device, as shown in Figure 12, or part of the ICD 100. The data store 400 being an external device, advantageously, facilitates compactness of the ICD 100. The data store 400 may be accessed by wireless communication. Although preferred embodiments have been shown and described, it will be appreciated by those skilled in the art that various changes and modifications might be made without departing from the scope of the invention, as defined in the appended claims and as described above. The optional features set out herein may be used either individually or in combination with each otherwhere appropriate and particularly in the combinations as set out in the accompanying claims. The optional features for each aspect or exemplary embodiment of the invention, as set out herein are also applicable to all other aspects or exemplary embodiments of the invention, where appropriate. In other words, the skilled person reading this specification should consider the optional features for each aspect or exemplary embodiment of the invention as interchangeable and combinable between different aspects and exemplary embodiments.

Claims

1. A method of reading an optically readable security element, using an image capturing device, the method comprising:establishing a relative configuration between the optically readable security element and the image capturing device, such that an illumination intensity gradient is present across the optically readable security element, whereby different regions of the optically readable security element are illuminated with different illumination intensities;reading the optically readable security element using the illumination intensity gradient, such that reading of different regions of the optically readable security element is undertaken with different illumination intensities;determining the relative configuration between the optically readable security element and the image capturing device;during or following reading the optically readable security element, determining a measured response of the optically readable security element to the illumination; andcomparing the measured response with an expected response of the optically readable security element to the illumination, the expected response being established based on the determined relative configuration.

2. The method according to claim 1, wherein determining the relative configuration between the optically readable security element and the image capturing device comprises:determining a map of values which relate to a distance between each different region of the optically readable security element and a light emitting element of the image capturing device.

3. The method according to claim 2, wherein the map of values is determined based on one or more of:information obtained by reading an engineered component of the optically readable security element;an orientation of the optically readable security element;an optical characteristic of a region of the optically readable security element or a region surrounding the optically readable security element;an output of a three-dimensional mapping process.

4. The method according to claim 2 or 3, further comprising:establishing the expected response based on the map of values.

5. The method according to claim 4, further comprising:establishing the expected response based on one or more of:information relating to composition of the optically readable security element;information relating to intensity of illumination of the optically readable security element, from a source of illumination;information relating to environmental conditions;information relating to a condition of the optically readable security element.

6. The method according to any one of the preceding claims, wherein the optically readable security element and the image capturing device are relatively configured to provide the illumination intensity gradient.

7. The method according to any one of the preceding claims, wherein the regions of the optically readable security element are regions of a second area, the second area comprising an identity.

8. The method according to claim 7, further comprising:during or following reading the optically readable security element, extracting the identity from the optically readable security element, and comparing the extracted identity with identities stored in a database.

9. The method according to any one of the preceding claims, wherein establishing the relative configuration between the optically readable security element and the image capturing device comprises:providing the image capturing device in an angled orientation relative to the optically readable security element, or adjusting an angle of orientation of the image capturing device relative to the optically readable security element;providing the optically readable security element in an angled orientation relative to the image capturing device, or adjusting an angle of orientation of the optically readable security element relative to the image capturing device;providing the optically readable security element on a non-planar surface, such that the optically readable security element has a non-planar form; and / orcausing the optically readable security element to adopt a non-planar form.

10. The method of any preceding claim, wherein the optically readable security element comprises one or more optical emitters arranged to be read via emission radiation emitted from the one or more optical emitters.

11. The method according to any preceding claim, wherein the optically readable security element comprises one or more optical emitters arranged to be excited by excitation radiation, optionally wherein the image capturing device is configured to emit the excitation radiation.

12. The method according to any preceding claims, wherein the method comprises capturing an image of the optically readable security element using the illumination intensity gradient, preferably capturing a single image of the optically readable security element using the illumination intensity gradient.

13. An image capturing device for reading an optically readable security element, the image capturing device comprising:a reader configured to read the optically readable security element; anda processor configured to:read the optically readable security element using an illumination intensity gradient, such that reading of different regions of the optically readable security element is undertaken with different illumination intensities.

14. The image capturing device according to claim 13, wherein the processor is further configured to:determine the relative configuration between the optically readable security element and the image capturing device;during or following reading the optically readable security element, determine a measured response of the optically readable security element to the illumination; andcompare the measured response with an expected response of the optically readable security element to the illumination, the expected response being established based on the determined relative configuration.

15. A system comprising:an optically readable security element; andan image capturing device according to claim 13 or 14.

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