Object marking, generation and authentication methods

Abstract

An object marking (9) comprising a first security element (3) and at least a second security element (4), wherein each security element (3, 4) is associated with a set of data segments (6, 7) and each security element (3, 4) presents a code segment as a function of capture conditions, in particular viewing angle (10) and / or lighting direction, which code segment is an electro-optically readable representation of one of the data segments (5) in the set associated with the respective security element (3, 4), wherein different distinguishable data segments are represented by different code segments (5) and the set associated with the first security element (3) and the set associated with the second security element (4) differ in at least one data segment; a method for generating an object marking and a method for authenticating an object marking.

Description

[0001] The present disclosure relates to an object marking comprising a first security element and at least a second security element, wherein each security element is associated with a set of data segments and each security element presents, depending on the capture conditions, in particular the viewing angle and / or the lighting direction, a code segment which is an electro-optically readable representation of one of the data segments in the set associated with the respective security element. Furthermore, the present disclosure relates to a set of object markings.

[0002] Furthermore, the disclosure relates to a base material for producing an object marking comprising a first security element and at least a second security element, wherein each security element is associated with a set of data segments and each security element presents, depending on the capture conditions, in particular the viewing angle and / or the lighting direction, a code segment which is an optoelectronically readable representation of one of the data segments in the set associated with the respective security element. The disclosure also relates to a method for authenticating an object marking and a method for producing an object marking.

[0003] In the prior art, various types of object markings for authentication or verification and base materials that can produce these object markings and methods for authenticating or verifying these object markings have been proposed. For example, WO 2018 / 046746 A1 shows a sheet product including a mark and a security feature. The mark is a machine-readable code. The security feature is implemented by a security device separate from the mark. The security device includes two optically variable devices (OVDs) placed side by side, such as different diffraction gratings that present different color changes that can be perceived, for example, by a camera or the naked eye. Therefore, by ensuring that the two OVDs look different, the presence of the security feature can be easily identified and verified using a programmable device including a camera. The security features all present substantially the same optically variable image, but with different starting angles. The sheet product has a plurality of different marks, each with a randomly selected security element next to it.

[0004] The optical diffraction effect, i.e. the image that an optically variable device "emits" or appears to present, depends on the lighting conditions and the viewing angle. In a typical setup, a point-like light source is assumed, and the properties of the diffraction grating forming the security feature are designed for this specific lighting scenario. During the design process, the physical structure is developed in such a way that it diffracts the incident light in a desired manner, i.e. presents a certain image at a certain (azimuth) angle. More specifically, a point-like light source at a specific position is assumed, and the diffraction grating is designed to present a specific image, such as a specific color or shape, at different specific viewing angles. Therefore, the known behavior of the security element is limited to this specific lighting scenario. Since the image presented by the optical diffraction security device essentially depends on the lighting conditions and the viewing angle, reading the actual content of the security feature becomes an inherently difficult problem in practice when defined environmental conditions cannot be ensured. Therefore, the optical diffraction security element will react unpredictably under uncontrolled conditions, at least to a certain extent. A typical way to overcome this problem is to provide some equipment or other means (such as user guidance, special actions, training...) to ensure that the conditions are at least similar to the environmental conditions used during the design process. The subject of the present invention is to overcome the limitations of the controlled environment used for verification.

[0005] The sheet product introduced in WO 2018 / 046746 A1 is specifically optimized for verification by a programmable device including a camera, where the marking is used to determine the expected behavior of the surrounding security features. However, in actual uncontrolled settings, there are very few instances where a defined lighting situation can be established during the verification process. Therefore, the reaction of the security device will be different from what was expected during the design process. Therefore, people are forced to extract lighting-invariant features from lighting-related optically variable security devices. Not surprisingly, this is an inherently difficult problem to solve, and there is always a trade-off between the rigor or accuracy of verification / certification and robustness to address the influence of uncontrollable lighting conditions and external unforeseen factors. This becomes particularly difficult if there is more than one point light source in the verification setting. In addition, diffuse illumination can be understood as an indefinite number of (weak) point light sources. In such a multi-light source setting, due to the lack of collimated incident light, different diffracted light beams are inevitably superimposed on the programmable device including the camera, ultimately generating multiple superimposed images visible at a single angle. There is no reliable way to filter and differentiate the superimposed reflections, and therefore verifying the correct emission of an image at a specific angle is a significant challenge.

[0006] Traditionally, the design of optically variable devices is mainly for the purpose of providing satisfactory optical effects. The security of such devices lies mainly in the use of structures that cannot be produced by others, even if replication becomes difficult. For verification, professional knowledge is required, and microstructures and nanostructures are usually evaluated under laboratory conditions to verify the correct physical structure of the grating. Automatic verification of macroscopic scales, such as based on the presented images, such as by computer vision means, is usually not considered at all. Prominent examples of optically variable devices in the prior art are rainbow holograms (zero-order / first-order diffraction gratings, usually with colored reflections) or animations of geometric shapes, such as rotating or moving objects, zoom effects (usually produced by nanostructures, micromirrors, etc.), etc. Due to the main goal of such OVDs, that is, to be visually satisfactory and verifiable under laboratory conditions, it is usually attempted to create seamless animations and continuous color changes. In the ideal case considered in this way, traditional optically variable devices are designed to have an indefinite number of images to provide a smooth optically variable effect, and these indefinite number of images are provided as a single area of ​​color that is colored with each other when the viewing angle is changed. In particular, for rainbow holograms, this is achieved by physical means because the incident white light is only diffracted at the grating. Since a rainbow hologram consists of only one "pixel" that exhibits a smooth transition of colors, these OVDs are unable to store or encode any form of distinct or distinctive data segments.

[0007] On the other hand, US 2012 / 0211567 A1 shows an animated barcode encoding a string of information, in particular a series of consecutive barcodes. An optical layer is provided to affect the display of different barcodes at different viewing angles, so that each barcode is displayed at a different viewing angle. The purpose of this solution is to increase the data capacity stored in a single barcode area. To achieve this goal, ideal lighting conditions are implicitly assumed and indeed required. However, as mentioned above, such lighting conditions, while perhaps acceptable for data storage applications, are not acceptable for security marking applications, where reliable and convenient authentication is key to user acceptance and ultimately necessary for uncovering fraud and forgery.

[0008] The object of the present invention is to overcome the inherent problem of unpredictable images in an uncontrolled authentication environment. In particular, the present disclosure will provide a special design of an optically variable security element for object marking that allows for more robust authentication using a programmable device including a camera while making less compromise in authentication accuracy and precision.

[0009] The present invention proposes an object tag as mentioned at the beginning, wherein different distinguishable data segments are represented by different code segments, and wherein the set associated with the first security element and the set associated with the second security element are different in at least one data segment. Therefore, each security element presents (i.e., displayed according to its light reflection characteristics) at least two different code segments according to the capture conditions. The capture conditions may include viewing angles and / or lighting directions, wherein the change of one or both is necessary for revealing different code segments. Each code segment is an optoelectronically readable representation of a data segment. The same data segment may be represented by one or more code segments. Each code segment just represents a data segment. The data segment represented by the code segment belongs to a limited set of data segments associated with the corresponding security element. The first security element is associated with the first data segment set. The second security element is associated with the second data segment set. Each set may include at least two data segments. The first data segment set is different from the second data segment set. For example, there may be at least one data segment located in the first set or the second set but not in the two sets. Therefore, the code segments presented by the security element and the final security element itself are different. The object tag may include more than two security elements that are different in the same sense; that is, the object tag may include three or more security elements associated with a corresponding number of data segment sets, wherein each set pair is different according to the above definition. In the group of the security element, each security element can therefore be distinguished from each other security element. Depending on the degree of similarity between the sets of interest (e.g., the number or ratio of data segments in more than one set), any two security elements in such a group can be distinguished by reading one or more code segments in the code segments of the set of interest under the capture conditions of the corresponding number. Each security element can present a predefined maximum number of code segments, so that at least when the code segments of the number are read from any two security elements, they can be distinguished.

[0010] Without limiting the scope of the present disclosure, the object tag may additionally include similar security elements, i.e., two or more security elements associated with the same data segment set. In the case of more than one group of similar security elements, these groups may differ in their size (i.e., the number of their security elements) and / or the relative arrangement between their members (e.g., the distance between the security elements from the same group or the direction of the nearest adjacent security element from the same group). These characteristics and measures provide: security elements that are different but similar can be distinguished by their respective adjacent (or continuous) dissimilar security elements. In other words, if adjacent (or continuous) dissimilar security elements can be read, then even similar security elements can usually be distinguished from each other. In essence, what happens is that two or more data segment sets are combined based on the geometric distance of the security elements they are associated with. Then, the set of the first combination and the set of the second combination are different in at least one data segment. In this case, for easier understanding, we refer to the different "neighborhoods" of security elements.

[0011] Distinguishing between different security elements or different neighborhoods can be used to increase the diversity of object markings that can be produced from a given base material. Increased diversity means that the probability that any two real object markings are the same or even similar is reduced. The work of counterfeiting object markings is proportional to the number of different instances that must be counterfeited, because copying the same instance usually requires relatively little work. In a preferred setting, this can be achieved by observing the relative frequency of verified object markings with the same indistinguishable pattern, which is therefore essentially a physically real replica. This observation can be made by capturing all verifications from a single verification device including a camera or from a database, in which verification data of multiple programmable devices including cameras are captured. Due to the low probability of a real replica, the threshold of the frequency of the replica may be low, and therefore if a counterfeit is used to produce a higher than average number of replicas, the counterfeit can be easily detected. Therefore, greater diversity makes counterfeiting without a negligible risk of detection more expensive and ultimately less attractive.

[0012] The present invention also proposes a set of object tags, wherein the set includes a plurality of object tags as defined above. For example, the set includes two or more object tags of the types defined above. The set of object tags, especially when it contains more than 100, more than 1000 or more than 10000 object tags, exhibits the statistical properties of a single object tag. Specifically, for example, the average repetition rate of a security element with any particular set of data segments or the repetition rate of a set of data segments in any particular neighborhood or combination can be determined based on the set of object tags, or the set size determines the upper limit of such a repetition frequency. In other words, the statistical properties of the set are quantitative and measurable expressions of the above-mentioned diversity.

[0013] In addition, the present invention proposes a basic material as mentioned at the beginning, wherein different distinguishable data segments are represented by different code segments, and the set associated with the first security element and the set associated with the second security element are different in at least one data segment. A basic material is provided for generating an object tag. Optionally, the basic material includes a sufficient number of security elements to generate at least two object tags or at least three object tags or more object tags. For example, the basic material may include a two-dimensional security element array with significantly more than two security elements, such as an array of at least 5x5 security elements or an array of at least 10x10 elements or an array of at least 20x20 security elements. Without limiting the scope of the present disclosure, the basic material, as explained above for a single object tag, may additionally include similar security elements, i.e., two or more security elements associated with the same data segment set. All of the above explanations about distinguishable "neighborhoods" for a single object tag are applicable to the basic material as similar possibilities. Furthermore, again without limiting the scope of the present disclosure, the base material may have a repeating sequence of security elements, wherein the period of repetition, i.e. the distance between repeated instances of the security element, is significantly larger than the size of a single object marking, for example at least ten times larger or at least a hundred times larger.

[0014] In addition, without limiting the scope of the present disclosure, the present invention proposes a method for generating an object mark by randomly or pseudo-randomly combining at least two different security elements. The random combination can be achieved by changing the "neighborhood" configuration of the distinguishable security device, that is, arranging the "neighborhood" configuration differently for different object marks. In order to generate a security device including at least two different security elements by the present method, the following device can be used: the device is configured to randomly or pseudo-randomly select the at least two different security elements from a limited set of distinguishable security elements and place the at least two different security elements in a specific geometric arrangement in a random or pseudo-random manner. More specifically, the security element can be pre-generated using any means suitable for generating an optically variable device. In addition, any registered transfer process suitable for transferring the pre-generated security element to a carrier material (forming an object mark) or the object itself can be used. For example, registered hot stamping or cold stamping, digital cold foil transfer, etc. can be used to transfer at least two OVD-like security elements to a carrier material or an object to generate a security device and object mark according to the present invention.

[0015] The invention also proposes a corresponding method for authenticating an object mark, the object mark comprising an optoelectronically discernible delimited area of ​​a base material (e.g., the object mark is optionally formed on a carrier material or directly on the object), wherein the base material is a base material as described above, wherein the area comprises a first security element and at least a second security element, the method comprising the following steps:

[0016] capturing a first image of the object marker from a first angle or under a first lighting direction;

[0017] identifying a first code segment presented by the first secure element in the first image;

[0018] decoding the first code segment to obtain a first data segment;

[0019] capturing a second image of the object marker from a second angle and / or under a second lighting direction;

[0020] identifying a second code segment presented by the first security element in the second image;

[0021] decoding the second code segment to obtain a second data segment;

[0022] It is determined whether there is a data segment set including the first data segment and the second data segment according to a model storing data segment sets associated with the security element of the base material.

[0023] The above method essentially checks whether the combination of data segments contained in the first security element has a corresponding set of data segments according to a defined storage model containing all valid sets of data segments. If no match is found, ie no corresponding set is found, the security element is likely to belong to a forged object tag.

[0024] For authentication purposes of a specific security element, it may be sufficient to observe only a subset of at least two code segments of all possible code segments of that specific security element. In a preferred arrangement, the authentication method can be set to confirm authenticity when N code segments out of M possible code segments (known according to the model) of the specific security element are observed from different angles or under different capture conditions (e.g., lighting). Examples of parameters N and M are: N=2 (N must be greater than or equal to 2), M=5 (M must be greater than or equal to N, for example, M=N+1, M=N+2, M=N+3, M=N+4). Since all code segments are independent, it is not important to decode N=2 out of M=5. Any combination is sufficient.

[0025] Often, it may be sufficient to change the viewing angle while keeping the illumination direction (eg the arrangement of the light source and the security element) unchanged for observing two or more different code segments of a specific security element.

[0026] Finally, the present invention proposes a method for generating an object tag, the method comprising the following steps:

[0027] randomly, pseudo-randomly or deterministically selecting a region of a base material, wherein the base material is a base material disclosed herein, the selected region comprising a first security element and at least a second security element, and

[0028] The selected regions are photoelectrically distinguishable from unselected portions of the base material.

[0029] The method for selecting the area of ​​the base material can contribute to the diversity of the object marking obtained. Random and pseudo-random selection ensure that no unintentional repetition with a reasonable relatively high repetition rate is caused. Therefore, these measures also increase diversity. The shape, size or any other photoelectric readable characteristics of the selection may vary. The selection can be completed by cutting or stamping from the base material, directly combining multiple security elements on the object or partially overprinting the base material and using a negative selection mask so that the base material is only visible in the mask area.

[0030] In another preferred arrangement, the proposed base material is particularly suitable for producing a safety device as proposed in WO 2015 / 079014 A1 and / or for a safety system introduced, for example, in WO 2013 / 188897 A1, since the selected positions in the base material are known by the model. In such a particular arrangement, the randomness introduced by the selection process (e.g. due to manufacturing tolerances) is combined with the a priori known geometric information from the model, which essentially maps the base material.

[0031] By providing a security element presenting a code segment that represents a data segment in an optoelectronic manner instead of a security element with, for example, a rainbow effect, i.e., a smooth color change, the authentication of the object tag is more robust. The reason for this is that it is possible to determine whether the code segment actually represents a valid data segment. The possibility that a random or diffuse lighting condition will cause an invalid security element to accidentally present a code segment representing a valid data segment is much lower than the possibility that an invalid color-shifted image or a simple geometric shape will accidentally display a valid image. In addition, by presenting a security element representing a code segment of a data segment, by scanning the code segment, the position of the code segment in the original base material (or one of a few valid positions) can be determined, and the validity of the code segment can be verified by a model that associates a data segment set (or neighborhood) with a position. In other words, the security element is used as a landmark in the model (the landmark, for example, maps the base material from which the object tag is generated). Since the security element is different in at least one data segment, the position can be determined by changing the capture condition. Alternatively or additionally, according to the set, the position can also be determined by capturing the first security element and the second security element only under a single capture condition and finding the corresponding combination of adjacent sets (of adjacent or adjacent security elements). In this case, "neighborhood" can be used as a landmark in the model. It is noteworthy that in order to authenticate at least one security element in this arrangement, at least a second code segment (and corresponding data segment) needs to be observed from at least a second different capture environment to ensure that the OVD is indeed present (rather than, for example, a printed copy representing the OVD in a single capture environment). It is also noteworthy that the object marking disclosed herein - and in particular the security element - does not allow the use of animated barcodes to encode more information than a conventional barcode. Rather, it allows the use of animated barcodes for authentication.

[0032] In the case of presentation according to capture conditions, the code segment is understood as the corresponding code segment being physically displayed in at least some form. In particular, there is at least one capture condition for each code segment, under which the code segment can be distinguished from other code segments of the security element and / or can be photoelectrically identified from the code segment of the data segment in the set representing the security element. The viewing angle refers to the viewing angle of the object mark, more particularly to the viewing angle of the corresponding security element. For practical applications, it is important to mention that, strictly speaking, the viewing angle and the capture conditions are already slightly different for adjacent security elements. This is a problem that is difficult to solve using traditional optically variable devices. One can design the optically variable device to have features that are so robust that the geometric offset can be ignored. Alternatively, it is impractical according to our experience that the capture conditions can be estimated based on the observed image from the presentation of the first code segment and a mathematical model for inferring the expected presentation of the second adjacent code segment.

[0033] The advantage that can be achieved using the present disclosure is that authentication is essentially a check whether a particular data segment belongs to a set of data segments of a particular security element. The verification method is very robust and no longer needs to account for the diversity of capture conditions that occur within a single captured image due to geometric distortions across security devices or more specifically across object markers.

[0034] The code segment of the second security element preferably does not overlap with the code segment of the first security element at least partially, more preferably completely. The code segment representing the data segment from the set associated with the first security element preferably does not overlap with the code segment representing the data segment from the set associated with the second security element at least partially, more preferably completely. In addition, the security elements themselves, i.e. the first security element and the second security element, may not overlap at least partially or (completely). That is, the first security element and the second security element may be arranged so that there is no overlap between the first security element and the second security element. The first security element and the second security element may, for example, be arranged adjacent to each other, adjacent to each other or at a distance.

[0035] Optionally, the set of data segments associated with each security element is an aggregate of data segments represented in an electro-optically readable manner by an aggregate of code segments presented under the overall capture condition. Optionally, for each data segment in the set of data segments associated with each security element, there is at least one code segment that represents the data segment in an electro-optically readable manner under at least one defined capture condition. That is, each code segment that represents in an electro-optically readable manner a data segment in the set of data segments associated with each security element is presented by the security element under at least one defined capture condition.

[0036] According to a specific embodiment of the present object marking, for a fixed lighting direction, each data segment in the set associated with the security element (and therefore, each code segment presented by the corresponding security element) is associated with a distinguished viewing angle area, in which the contrast of the code segment representing the corresponding data segment is higher than the contrast of the code segment representing all other data segments from the same set. In other words, the code segment is associated with a viewing angle range or area where they can be read. On the contrary, each viewing angle is attributed to only one specific code segment (therefore, data segment), but each code segment can be visible from multiple different viewing angles. The viewing angle range usually depends on the actual lighting, and may indeed overlap in the case of multiple distributed light sources. It is also worth noting that in practical applications, a specific data segment may be associated with a plurality of distinguished viewing angles or viewing angle areas, wherein each viewing angle or viewing angle area may only be attributed to exactly one data segment, that is, there may be a mutually exclusive distribution of viewing angles or viewing angle areas between the data segments of a specific set associated with the security element.

[0037] In this context, there may optionally be at least one viewing angle region associated with the data segments of the set of first security elements, which is different from each of the viewing angle regions associated with the data segments of the set of second security elements. Therefore, there may be at least one viewing angle at which the first security element changes the presented code segment and the second security element does not change the presented code segment. More generally, the switching characteristics may be different between the first security element and the second security element. For example, due to the different sizes of the first data segment set and the second data segment set, the switching characteristics may be different: for example, the first data segment set may consist of nine data segments, and the second data segment set may consist of 18 data segments, wherein the first security element presents a different code segment (i.e., switching) every 20° between 0° and 180° viewing angles, and the second security element presents a different code segment (i.e., switching) every 10° between 0° and 180° viewing angles.

[0038] Each code segment can be a structured image, specifically a barcode-like structure, preferably a two-dimensional code, and more preferably a two-dimensional array code. These types of images are relatively easy to read out photoelectrically. In particular, the structured image can provide sufficient contrast to distinguish the structure under different lighting conditions.

[0039] More specifically, each code segment may be a two-dimensional array code, wherein each code segment is an array of tiles, and the data segment is represented by the code segment selecting one of at least two optically distinguishable states (e.g., dark or light, black or white) through each of the tiles of the code segment, wherein the code segment presented by the first security element is arranged adjacent to the code segment presented by the second security element. The two-dimensional array code may have no delimitation and / or no search pattern between adjacent tiles of the code segment.

[0040] According to an embodiment of the present disclosure, each code segment may represent a corresponding data segment in a predefined encoding, wherein the predefined encoding preferably includes information for error detection or error correction.

[0041] Optionally, the predefined encoding may allow a maximum number of possible distinguishable data segments, and the number of data segments in the data segment set of each security element may be less than 1 / 100 of the maximum number of possible distinguishable data segments, preferably less than 1 / 1000, and more preferably less than 1 / 10000. In other words, only a small portion of the possible data segments (and therefore the code segments) may actually be used. Assuming that a read error will involve all parts of the code segment roughly equally, this can be used to detect a read error because a read error is likely to result in an unused read data segment. In this regard, the data segments used can be selected so that, for example, a code segment representing the data segments used is different on more than one tile (in the case of a tile-shaped two-dimensional array code)-preferably more than two tiles-so that a single flipped tile will result in an unused data segment and therefore a detectable read error.

[0042] The positions of the security elements relative to each other can be predetermined. These positions can be stored in a model, for example, and used to identify and distinguish neighbourhoods of otherwise (at least partially) similar security devices, thereby increasing the diversity of distinguishable object markers.

[0043] Thus, with respect to the base material, the positions of the security elements relative to each other on the base material may be predetermined according to the model, and the data segments of the set associated with the security elements may be predetermined according to the model.

[0044] Thus, when an object marking is generated by placing security elements randomly, pseudo-randomly or deterministically in a geometric arrangement, the positions of the security elements may be recorded in a model or database. This information may be accessed during authentication.

[0045] Optionally, each code segment can represent the corresponding data segment in a predefined encoding, wherein the predefined encoding preferably includes information for error detection or error correction. Error detection is particularly useful for triggering the re-reading (i.e. repeated reading attempts) of the relevant code segment, wherein such re-reading will generally be advantageously performed under different lighting conditions, thereby increasing the chance of not repeating the same reading error. Error correction provides a more robust photoelectric readout of the code segment, wherein a small portion of the reading error of the code segment can generally be tolerated. Therefore, both error detection and error correction contribute to the robustness of the readout. This reduces the possibility that the real object tag will be rejected (false rejection). It is worth mentioning that, in particular, the use of known error correction codes such as Reed-Solomon is considered to be easily decoded by errors when used for very small data segments such as 16 bits, but the error correction capability is high.

[0046] As an extension of what is discussed above for individual object markings, the predefined encoding may allow for a maximum number of possible distinct data segments, and the number of distinct data segments in the set of data segments for all security elements (i.e., on the base material) may be less than 1 / 100, preferably less than 1 / 1000, and more preferably less than 1 / 10000 of the maximum number of possible distinct data segments. As mentioned above, this sparse use of data segments may be exploited to further minimize the number of false rejections for known vulnerabilities in error correction codes with very small data segments.

[0047] Regarding the method for authenticating an object identity, the method may further include the following steps:

[0048] identifying a third code segment presented by the second security element in the first image or the second image;

[0049] decoding the third code segment to obtain a third data segment;

[0050] It is determined whether a second security element positioned relative to the first security element is associated with a set of data segments containing a third data segment based on a model storing a set of data segments associated with security elements of base material and storing the relative positions of security elements of base material to each other. In this case, the optically variable property of the second security element is verified and, in addition, the contained information is used to increase the diversity of the object marking.

[0051] According to a specific embodiment of the present method for authentication, the security elements of the base material may be arranged in a tiled manner, wherein the object tag comprises a portion of the security element, and each code segment presented by the security element is an array of tiles, and the code segments presented by one security element are arranged to have a spread to the code segments presented by other security elements, so as to form a larger array of tiles, wherein the method further comprises the following steps:

[0052] a) identifying a first sample block in a first image;

[0053] b) decoding a first sample code segment in a first image to obtain a first sample data segment, the first sample code segment being formed by a first sample tile array comprising the first sample tile at a predefined position;

[0054] c) determining, according to a model storing sets of data segments associated with security elements of base material, whether there is at least one set of data segments containing said first sample data segment;

[0055] d) if such a set cannot be determined in step c), repeating steps a) to c) using different first sample tiles until such a set is found in step c); and

[0056] 1) Identify the current first sample code segment as the first code segment.

[0057] Optionally, more specifically, the method may further include the following steps before step 1):

[0058] e) identifying a first sample block in the second image;

[0059] f) decoding a second sample code segment formed by the first sample tile array in the second image to obtain a second sample data segment;

[0060] g) determining, based on a model storing sets of data segments associated with the security element of the base material, whether at least one of the at least one sets containing the first sample data segment contains the second sample data segment;

[0061] h) if no such set can be determined in step g), repeating steps a) to g) until such a set is found in step g); and

[0062] m) Identify the current second sample code segment as the second code segment.

[0063] Finally, in order to optionally further refine the method for authentication, the method may also include, before step l) - and, if applicable, before step m) - the following steps:

[0064] i) decoding a third sample code segment formed by a second sample tile array positioned relative to the first sample tile array to obtain a third sample data segment;

[0065] j) determining, based on a model storing sets of data segments associated with security elements of base material and storing relative positions of security elements of base material to each other, whether the third sample data segment is contained in the following sets of data segments belonging to security elements respectively positioned relative to the security elements belonging to the sets preliminarily identified in step e);

[0066] k) if no such set can be determined in step j), repeating steps a) to d) and steps i) to j) and preferably steps e) to h) until such a set is found in step j);

[0067] n) Identify the current third sample code segment as the third code segment.

[0068] Reference is now made to the accompanying drawings, which are for the purpose of illustrating the present disclosure and not for the purpose of limiting the same.

[0069] Figure 1a schematically illustrates a first embodiment of a base material for producing an object marking having six complete security elements according to the present disclosure, and visually indicating below the object marking two sets of data segments associated with two of the security elements;

[0070] Figure 1b The object labels are schematically shown, and the code segments presented at three different viewing angles are indicated;

[0071] Figure 2 schematically illustrates a second embodiment of a base material for producing an object marking having sixteen security devices according to the present disclosure, the sixteen security devices presenting a two-dimensional array code as code segments, wherein the code segments at different viewing angles are indicated; and

[0072] Figure 3a to Figure 3c A method for authenticating an object token according to the present disclosure is schematically illustrated.

[0073] As a basic building block of the base material 1 and the object mark 8 thus produced according to the present disclosure, a security element 2 optimized to be able to be verified using a programmable device including a camera is proposed in a first embodiment. The security elements 2 of the base material 1 can each only display a very limited, discrete set of distinguishable images. This means that: due to the indefinite number of possible combinations of lighting settings and viewing angles, each image in this limited set will be visible from multiple viewing angles. In fact, such a security device 2 can be designed by creating an optical element that presents a specific picture within a range of (azimuth) angles, i.e., displays the same picture within a range of + / - 5 degrees. This can be achieved by cylindrical lenses, diffraction gratings, micromirrors and microlenses, nanostructures, etc.

[0074] The displayed image of the security element can be an image in the "traditional" sense, such as a geometric shape, a combination of shapes, different colors, a pixelated image, etc. In the present disclosure, these images are also referred to as code segments. Subsequently, we will show different possible structures of the base material (usually a sheet product) and different embodiments of the present disclosure.

[0075] In order to summarize the main functions of the present disclosure, for the purpose of illustration, we Figure 1a The following setting is assumed in : In this setting, the set of available images consists of images of lowercase characters from the Latin alphabet, namely {a...z}. Figure 1a A part of the proposed base material 1 comprising a plurality of security elements 2 is also presented exemplarily. For easier understanding, we focus the explanation on the first security element 3 and the second security element 4. The first security element 3 is configured to present, depending on the viewing angle, one image (or typically a code segment) 5 from a first set of images 6 (or typically a code segment representing a data segment from a first set of data segments). The second security element 4 is configured to present, depending on the viewing angle, one image (or typically a code segment) 5 from a second set of images 7 (or typically a code segment representing a data segment from a second set of data segments). The number of images in the two sets 6, 7 as well as the angular coherence may be different, i.e. the images in the first set 6 may have different switching characteristics than the images in the set 7. Furthermore, certain images may appear in multiple sets, for example in 6 and 7, as long as the sets themselves are distinguishable, i.e. not all elements are equal.

[0076] As previously described, various generation processes can generate selection or object labels 9 from base material 1.

[0077] Figure 1b By way of example, an object marking 9 is shown after selection from the base material 1 , which object marking 9 contains the first security element 3 and the second security element 5 . Figure 1b Also shown are the selected presented images (or code segments) 5 when viewed from different angles 10. When viewed from a first angle 10α, the first security element 3 displays an image (or code) "a" which is a member of a set of images 6 corresponding to the first security element 3. At the same viewing angle, the second security element 4 displays an image (or code) "z" which is a member of a set of images 7 corresponding to the second security element 4.

[0078] Similarly, at angle 10β, the first security element 3 presents "s" and the second security element 4 presents "v", both "s" and "v" being members of the respective image sets 6, 7. We should note that due to the very limited set of available images and the indefinite number of possible lighting / perspective scenarios, different combinations or all combinations of images may be possible. For example, at observation angle 10γ, the first security element 3 again displays image "a" 5 (similar to angle 10α), while the second security element 4 displays image "b" 5. Such a scenario may also occur if different switching characteristics, i.e. different optical elements and characteristics, are used for different security elements 2 in the design of the base material 1. The first security element 3 may also have, in addition to having a different image set, a different switching characteristic / switching angle than the second security element 4.

[0079] As a notation, for clarity in subsequent figures, we will use capital letters A...P to represent different security elements 2. We will use the letter "A" to represent the first security element 3, and the letter "B" to represent the second security element 4, etc. The first image (or code segment) 5 in the image set 6 will then be represented as A_1, the second image (or code segment) 5 will be represented as A_2, etc. Similarly, the image (or code segment) 5 of the second security element 4 of the corresponding second image set 7 will be represented as B_1, the second image (or code segment) 5 will be represented as B_2, etc. In the simplest case, each code segment has a 1:1 relationship with the corresponding data segment. However, the scope of the present disclosure extends to the case where multiple code segments (e.g., A_1.1, A_1.2, etc.) can represent the same data segment (e.g., A_1). Related to the set is the data segment. For simplicity, in conjunction with the description of the subsequent figures, we will use the terms image, code segment, and data segment synonymously and mark them as 5.

[0080] In practical applications, when computer vision means are used on a programmable device including a camera to verify or read certain images, the correctness of the reading / decoding of the image itself is always a problem. Although the color shift image example mentioned above sounds quite simple, reading and classifying colors (absolutely and even relatively) is still a very difficult problem in the field of computer vision. Therefore, it is not recommended to choose different colors as different presented images. Geometric shapes or structured images with good contrast are more reliable to read and decode, but it is still almost impossible to completely avoid decoding errors without taking any additional measures. Therefore, in practical applications, using generic images or even letter images (such as those used in Figure 1) will bring no small problems, but in fact almost error-free reading is required. This is indeed what is desired for the current purpose, because we need a reliable method to determine whether its data segment representation is a member of the data segment set of this particular security element based on the decoded image. We certainly do not want to hinder consumer adoption by rejecting real object tags due to reading errors.

[0081] In a preferred embodiment, the images 5 are designed in such a way that they can be read easily and almost error-free in an automatic manner by a programmable device including a camera. One possible measure to ensure correct readability is to embed a checksum-like / parity-like structure in each of the possible images. This concept is well known in the field of telecommunications; the image is structured into at least two individually readable / decodable parts and there is a relationship between these parts. In the field of information technology, these parts are usually called "codewords" - "payload" and "parity", respectively. The codewords / parts are read and decoded individually and the decoding results are then matched to each other. If the decoding results match, it is confirmed that a correct reading has been performed. Prominent methods implemented in the field of information technology are checksums, cyclic redundancy check codes (CRC) or error correction (EC) codes. In the field of visually decodable barcodes, in particular Reed-Solomon encoding - an example of EC codes - is popular.

[0082] Therefore, as a possible implementation of the present disclosure, we propose to use an image 5 that is optimized for robust readability / decodability using a programmable device including a camera. An intuitive choice is to use a barcode-like structure such as a QR code or a pixel-level structure that represents a codeword encoded using an EC code such as Reed-Solomon encoding.

[0083] Such encoding provides the possibility to encode any type of digital data segment, such as numbers, alphanumeric numbers, binary data, etc. In a preferred arrangement, numerical or alphanumeric identifiers can be encoded in a 2D-like structure and a set of possible images corresponds to a set of encoded identifiers.

[0084] While standard barcode structures such as DataMatrix-Codes, QR-Codes etc. can be used, we recommend using codeword arrangements and custom structures using error correction coding such as Reed-Solomon coding. This is more efficient in terms of space and data capacity, i.e. increases the number of possible images. This is due to the fact that these standard barcode structures use special structures or patterns to encode version information, use Finder patterns to locate and determine the size of the code in the image etc. We propose methods later in this document to locate and decode such structures without the need for the commonly used finder patterns etc.

[0085] According to, for example, US 2012 / 0211567 A1, it is known to use an optical diffraction layer to display different spatially overlapping linked barcode structures depending on the viewing angle. US 2012 / 0211567 A1 proposes the use of an optical layer, which acts in such a way that different barcodes are displayed when viewed from different angles. They also propose the use of a code to link these at least two view-dependent codes together and to determine their order. The main purpose of the invention seems to be to increase the data storage capacity, so efforts are made to establish links so that the data can be reassembled into one data segment when reading different codes.

[0086] We want to understand that in the present invention, the view-dependent images / code segments / data segments are independent of each other. In addition, in contrast to data storage applications, the present invention is designed to require only a small portion of the data segments from a specific set of data segments to be decoded. The order of decoding is irrelevant, because only the membership of the decoded data segments to a specific set of data segments identifying a specific security element is important. Finally, the subject of the present invention is to identify the location of the security element within the base material by the following operations: by using the prior knowledge of the model to determine the identity of the specific security element and the location within the base material by decoding at least one data segment from at least one view, preferably taking into account the decoding of other code segments under different capture conditions and determining their corresponding set membership, the model stores the set of data segments that identify the security element and their geometric relationship to each other. Therefore, in strong contrast to, for example, US 2012 / 0211567 A1, instead of (physically) encoding the link information and the order information within the data segments / code segments themselves, the relationship between different data segments / code segments is determined by a predetermined model.

[0087] Figure 2 A preferred embodiment of the present disclosure is shown. The range of possible images is limited by 6×6 pixels, which can be black or white. The base material 1 includes a plurality of security elements 2 arranged in a tiled manner. For example, a first security element 3 identified as security element A is placed adjacent (or directly adjacent) to a second security element 4 identified as security element B. Each of the security elements 2 implements an optically variable element that displays one of N different images when viewed from different angles or lighting conditions. Therefore, the first security element 3 identified as security element A can switch between N different images A_1, A_2, ... A_N (5) in a possible image set 6 for the particular security element under different capture conditions α, β, ... ω. A similar second image set 7 with available images B_1, B_2, ... B_N is defined for the second security element 4.

[0088] It is worth mentioning that in practical settings, there is a trade-off between switching sensitivity, i.e. the "speed" of the switching effect, and robustness. In particular, if there is diffuse illumination or multiple point-like light sources with similar intensities, crosstalk between multiple images may occur, i.e. two or more of the N images in the set of M possible images may be superimposed with different intensities. In this case, the error correction function becomes particularly useful, as it allows to filter between the superimposed images to a certain extent, or at least determine that the image cannot be reliably read under the current conditions.

[0089] In a practical setting, there is usually more than one illumination (light) source during readout. For example, there may be a dedicated light source linked to the verification device including the camera. When operating under realistic conditions, there is always a certain residual of ambient light, or there may even be point-like light sources (lamps, sun...) superimposed with the dedicated light source. In another practical setting, there may be no dedicated light source, but a superposition of multiple "natural" light sources. In addition, it may be beneficial to equip the verification device including the camera with multiple dedicated light sources, which can be turned on and off one at a time, or turned on simultaneously in a preferred setting, thereby creating a mixture of different more or less directional light sources.

[0090] Crosstalk between multiple images caused by multiple light sources or diffuse light can be exploited during readout. Based on the information learned from the model and utilizing error correction functions, the superimposed image can be decomposed and multiple code segments decoded. This allows, in certain cases, to verify a security element from a single captured image if the superimposed image can be successfully decomposed into at least two different code segments belonging to the set of available code segments for a specific security element. A very simple method to achieve such a decomposition is as follows:

[0091] - Based on the superimposed image, determining the intensity of the main code segment in the superimposed image (e.g., by gray value and histogram analysis)

[0092] - Filter all other intensities to isolate the prominent code segments

[0093] -Decode the separated highlighted code segments

[0094] - Determining the corresponding secure element and thus the set of available code segments for the specific secure element.

[0095] - Likewise continue with other possible intensities and try decoding.

[0096] If there is a second code segment that can be decoded and matches the set of available code segments for a particular secure element, then the secure element can be considered valid and authentic.

[0097] In another preferred arrangement, people may not try to find the strength of the main code segment, but simply iterate over all possible strengths. For each strength, separate the "possible" code segment. If the "possible" code segment is decodable, i.e., error correction and error detection are successful, it is assumed that the code segment is a valid code segment and the corresponding safety element is determined. Then iterate over the remaining possible strengths, filter for each strength and attempt to decode the possible code segments under these strengths. If there is at least a second strength in which the code segment can be decoded and the code segment is a member of the set of available code segments of the corresponding safety element, the safety element can be considered to be authentic.

[0098] In each of these cases, provided that the lighting environment includes an appropriate superposition of light sources suitable for separating and filtering the different code segments, the authenticity of the security element (and therefore at least a portion of the security device) can be verified from a single captured image.

[0099] In the current example of 6×6 pixels, the number of distinguishable pictures is theoretically 2^36. In a simple setting, this would mean that we can encode 2^36 different identifiers. However, in this case, there is no room for error correction and correct decoding cannot be ensured. If error correction coding is used, for example we can use 12 bits for error correction and 24 bits for the payload, so the number of distinguishable images can be reduced to 2^24.

[0100] If we choose a small number, for example N=5 images, this allows, for each set of images 6, 7 for the first security element 3 and the second security element 4, to "encode" a fairly large area of ​​the sheet product by simply placing the security elements in a tiled manner on the sheet product. However, practical applications require more robust error correction capabilities, especially when using smartphones or tablets with poor capture quality as verification programmable devices including cameras. With such a fault tolerance and high redundancy setting (e.g. 16-bit payload, 20-bit error correction), a considerable amount of "corrupted" data (e.g. due to poor capture quality, wrong binarization and classification, etc.) can be corrected. This is at the expense of making erroneous readings - i.e. decoding of the wrong identifier - more likely or more likely.

[0101] In a verification setting, one can then benefit from having a model of the sheet product - i.e. the set of possible images of each security element - available to a verification programmable device including a camera. This model is known a priori because it is derived as a blueprint for designing the sheet product. While one erroneous read may undoubtedly have occurred with a fairly low probability in a high redundancy setting as described above, the probability that a second decoding will lead to an erroneous read again is extremely small, especially the probability that these two erroneous reads correspond to two image members of the same set of N=5 images (of, for example, 2^16 available images). Therefore, by using two images from different angles of the same security element and checking whether the two identifiers are part of the set of images that define this particular security element, erroneous reads can be further reduced or actually eliminated.

[0102] Alternatively or in addition, one may use the spatial relationship of different security elements relative to each other. Thus, for example, if an erroneous image such as P_2 is decoded in a first security element (having the modeled set of available images A_1 ... A_N (6)) and B_2 is decoded correctly in an adjacent second security element (having the set 7: B_1 ... B_N), then it will be apparent from the model that one of the two must have been an erroneous decoding. If a first region 3 decodes to image 5 in the set 6: A_1 ... A_N and a second region 4 decodes to image 5 in the set 7: B1 ... B_N, then this can be safely assumed to be two correct reads. What we want to understand is that such geometric relationships embedded in the model may be particularly useful for minimizing the chances of erroneous decodings when using images without error detection / error correction capabilities.

[0103] Typically, for example for standard 2D code formats, there are no such small codes as 6×6 elements, simply because the risk of erroneous decoding with such a short payload is generally too high for practical applications. Nevertheless and similar to what is outlined above, the present disclosure allows such small codes to be used in a nearly error-free reading setting by exploiting the angle and / or spatial relationship of the images. This is made possible by increasing the decoding correctness by using a priori knowledge that can be obtained from a predetermined model of the sheet product in a programmable device including a camera. The benefit of using such small codes, compared to more suitable code sizes (e.g. 10×10 and higher), is that security devices that need to include at least one security element can be made smaller and still be decoded nearly error-free.

[0104] In such an arrangement, even if decoding of at least two security elements is used and a model of the base material is employed to confirm the correct decoding, it is virtually impossible for an erroneous decoding to occur.

[0105] Having a nearly error-free way to decode images, or more precisely determine a suitable set of possible images, enables two beneficial settings:

[0106] - A security element characterized by its set of possible images can act as an identifier (unique or nearly unique) due to its absolute position within the base material. It should be noted that not all N images need to be decoded to determine the set of possible images and identify the corresponding security element. For example, it is sufficient if two images from different angles are decoded and the set containing these two images can be determined based on the available models of the sheet product. Assume the fact that the sets are structured in such a way that no set can contain the same image pair as any other set / so that the image pair in this assumed embodiment is unique among all sets in the base material.

[0107] -Encoding in the security element does not require a typical structure of a two-dimensional code, such as a finder pattern, a frequency pattern or any other segmentation / positioning measure. Security elements can be placed adjacent to each other in a tiled manner without any indicator of where one security element ends and the next security element begins. High specificity (low probability of false reading) allows sliding the window pixel by pixel on the currently displayed image. Decode each possible position. If the possible position can be decoded (i.e., extract the identifier), all possible sets containing the specific image / identifier are predetermined according to the model. In the second step, images with different spaces or different angles are decoded. In the case of images with different angles (i.e., from the second captured image), all predetermined sets are searched to find the second decoded identifier. All sets that do not contain the second image, the identifier are no longer candidates. By iteratively performing this operation, only one set will be retained, which identifies the security element and allows the boundary of the security element to be defined at the same time, so that subsequent reading is performed in other captured images. In the case of using images with different spaces, the same captured image can be used. Assuming a 6×6 code: for each candidate position where an identifier can be decoded, the programmable device including the camera is also configured to try to decode adjacent 6×6 areas. If any of these areas is decodable, all possible sets of that area are determined, leaving us with a set of potentially identifiable security elements. By using the spatial relationship of two observed security elements to each other, and matching this spatial relationship with the relationship of the set of identifiers and the predetermined model, one can find matching combinations (e.g. pairs of adjacent sets) and identify again two adjacent security elements as well as the boundaries of the security elements - because they are arranged in a tiled manner. Naturally, if the encoding allows, the unused bits can be set to a specific bit pattern, which can be used to design heuristic methods and speed up the process of finding decodable areas, i.e. security element locations and boundaries.

[0108] The present disclosure is by no means limited to relatively small image sizes, i.e., 6×6 pixels. The above-mentioned identification strategies may not be necessary for larger images, since the error correction code is specific enough to prevent erroneous readings initially from a specific size (i.e., Nr bits) onwards. In the case of larger codes with more capacity, one may not need additional strategies to avoid erroneous decoding by using prior knowledge from a predefined model. In such a setting with a larger code, the sheet product can be encoded in such a way that each identifier only appears once or not twice in a certain local neighborhood - assuming that adjacent code pairs are used to identify the position in the base material. Therefore, due to the high specificity / almost error-free decoding provided by the code with a relatively large capacity / size and the fact that each identifier can be contained to the greatest extent. A successful decoding of a set of possible images is sufficient to determine the boundaries of the security element and identify the specific security element (thus knowing the exact absolute position within the sheet product).

[0109] One main goal is that the reason for using a programmable device including a camera together with an optically variable device is to provide an automated way to verify the presence of the optically variable device and therefore its authenticity. In the absence of any additional equipment besides the camera, this is usually achieved by computer vision means and a computer program configured to evaluate multiple images captured from different angles and / or lighting conditions, i.e., video streams. Alternatively, multiple simultaneously captured images from multiple cameras can be processed. The latest technology here is to evaluate the color changes of images or shapes (zero / first order diffraction devices) or certain animation effects, switching contrast, etc. Due to the uncontrolled environment, the trade-off between security and robustness / readability is substantial, i.e., only moderate specificity can be achieved-therefore security is achieved. Typically, if high security is a concern, a second evaluation line is adopted in the authentication process, which uses forensic equipment or dedicated reading equipment to evaluate the physical structure of the OVD rather than the reflective properties.

[0110] At the same time, applications employing standard equipment (such as programmable devices containing cameras) are generally intended to enable untrained users to verify the authenticity of security devices, where the user expects a convenient (and therefore robust) authentication process. Therefore, the OVD or even the presence of the OVD can only be roughly assessed at best. In the context of color-changing OVDs, this means, for example, that accepting "any" color change is generally a method of at least confirming the presence of the OVD. Confirming the presence of the OVD is generally necessary to distinguish the 3-dimensional OVD forming the security device from its picture / photo copy. Typically, under different kinds of adverse capture conditions (e.g., diffuse lighting), adverse changes in illumination or capture artifacts result in more changes in color changes, blurriness, etc. in the captured image of the printed copy of the OVD ("photo copy") than the original OVD would present. Therefore, the decision threshold of binary OVD presence detection (yes / no) is generally close to the point where the printed copy is accepted as an OVD under certain conditions, while the real OVD is rejected due to the lack of significant differences in the captured image (e.g., only small color changes).

[0111] The subject of the present disclosure is also a method that provides a way to very reliably confirm the presence of an optically variable device. By capturing at least two images from different angles / illumination settings and decoding at least two images of the same security element - which naturally need to be present in the set of possible images of that particular security element - in combination with error correction, the presence of an OVD is almost certain, since photographic copies or printed reproductions cannot exhibit this image switching behavior. Furthermore, the code switching is error corrected by the coding of the mark - which means that if a change in the image is observed, the chance of error is negligible.

[0112] Figure 3a to Figure 3c Involved in certification Figure 2 Method for marking an object made of a base material 1. In this example, the object marking includes a portion of the base material 1, wherein the portion is partially covered by a mask layer. The security elements 2 of the base material 1 are arranged in a tiled manner. Each code segment presented by the security element is a (secondary, monochrome) tile array. The code segments presented by one security element are arranged to have spread to the code segments presented by other security elements, so that a larger (secondary, monochrome) tile array is formed overall. The mask layer retains a defined area of ​​the base material 1 that is photoelectrically discernible. The area includes a first security element 3 and a second security element 4.

[0113] The method for authenticating the object marker comprises capturing a first image 12 of the object marker from a first angle or under a first lighting direction. Figure 3aThe first image 12 shown in the figure depicts the visual appearance of a bounded area discernible electro-optically under a first capture condition (e.g. a first viewing angle). The method comprises identifying a first sample code segment 13 (wherein "sample" indicates that the first sample code segment is a candidate for a first code segment) presented in the first image 12 by a presumed first security element. For the purpose of identifying the actual first code segment, the first sample code segment 13 is decoded to obtain a first sample data segment 15. In more detail, in step a), a first sample tile 11 is identified in the first image 12. Then in step b), the first sample code segment 13 in the first image 12 formed by a first sample tile array 14 including the first sample tile 11 at a predefined position is decoded to obtain a first sample data segment 15. Based on the first sample data segment 15, in step c), it is determined whether there is at least one data segment set 6 containing the first sample data segment 15 (i.e. a data segment candidate) according to a model 16 storing data segment sets associated with security elements of the base material 1. If no such set can be determined in step c), the data segment candidate is rejected and steps a) to c) are repeated using different first sample tiles until such a set is found in step c). For example, the next tile to the right of the first sample tile 11 can be identified as the new "first sample tile" and the above steps repeated. This can be repeated until a number of steps corresponding to a predetermined (known) width of the security element with respect to tiles (here the width is six tiles) are covered, and then the tile immediately below the initial first sample tile 11 can be identified as the new "first example tile" and the above steps repeated, and so on. Once at least one data segment set 6 containing a first sample data segment 15 (i.e., a data segment candidate) can be found - for example, in Figure 3a In the example, the set A includes A_1, and the current first sample code segment 13 is preliminarily identified as the first code segment.

[0114] In the absence of a particular sequence or order, the method further comprises capturing a second image 17 of the object marker under different capture conditions (e.g., from a second angle and / or under a second lighting direction). Figure 3b. A second code segment presented by the first security element is identified in the second image 17. For the purpose of identifying the second code segment, the second sample code segment 18 is decoded to obtain a second sample data segment 19. This can function similarly as for the first data segment. That is, in step e), a first sample tile 11 is identified in the second image 17 (usually an arbitrary one, such as the tile closest to the upper left corner of the second image 17); in step f), the second sample code segment 18 formed by the first sample tile array 14 in the second image 17 is decoded to obtain a second sample data segment 19; in step g), it is determined from the model 16 whether at least one of the sets containing the first sample data segment 15 in the model 16 also contains the second sample data segment 19; if no such set can be determined in step g), step h) indicates a loop and steps a) to g) are repeated until such a set 6 is found in step g). In practice this means that if no matching second sample code segment can be identified, the first sample code segment is rejected, so that the two sample code segments are released, thereby scanning different tile positions and boundaries until a valid combination of sample code segments is found. On the other hand, when a set with the two sample data segments is found, the current second sample code segment 18 is identified as the second code segment in step m). That is, the method determines whether there is a data segment set containing the first sample data segment 15 and the second sample data segment 19 based on the model 16 storing the data segment sets associated with the security element of the base material 1. Only in the affirmative case, i.e. if such a data segment set 6 is part of the model 16, the object marking can be determined as authentic.

[0115] In addition, if Figure 3cAs shown, the method includes identifying a third sample code segment presented by a hypothetical second security element in the first image 12 (but the second image 17 or both may be used similarly). The identified third code segment is decoded to obtain a third sample data segment. Based on the decoded third sample data segment, it is determined according to the model whether there is a second security element positioned relative to the first security element (identified by the first sample data segment and the second sample data segment) associated with the set of data segments containing the third sample data segment. Therefore, the model 16 not only stores the set of data segments associated with the security elements of the base material, but also stores the relative positions of the security elements of the base material to each other. Therefore, before confirming the authenticity of the object mark, the method includes: in step i), decoding the third sample code segment 20 formed by the second sample tile array 21 positioned relative to the first sample tile array 14 to obtain a third sample data segment 22; in step j), determining whether the third sample data segment 22 is contained in a data segment set 7 belonging to a security element 4 positioned relative to the security element 3 to which the sets preliminarily identified by searching for sets with the first sample data segment and the second sample data segment belong according to the model 16 including the data segment sets 6, 7 associated with the security element 2 of the base material 1 and the relative positions of the security element 2 of the base material 1 and another security element 23; if such a set cannot be determined, returning in step k) and repeating steps a) to j) until such a set is found; and once such a set is found, identifying the current sample code segment 13, 18, 20 as a valid code segment in step n). Therefore, the model 16 includes the following information: which data segment sets are associated with consecutive security devices on the base material 1.

[0116] In summary, the above method basically scans the (at least) two images 12, 17 in the tile array as follows: starting from an arbitrary tile and selecting a different tile at each round until a data segment represented by a code segment is offset from a given tile and the respective arrangement of said data segments produces a match in the model 16. If no such match is found, the object labeling is rejected (i.e. the authenticity cannot be confirmed).

Claims

1. A method for authenticating an object marking (9), said object marking comprising an optoelectronically discernible delimited area of ​​a base material (1), in, The basic materials include: a first security element (3) and at least a second security element (4), wherein each security element (3, 4) is associated with a set of data segments and each security element (3, 4) presents a code segment (5) according to a capture condition, said code segment being an electro-optically readable representation of one of the data segments of said set associated with the respective security element (3, 4), wherein different distinct data segments are represented by different code segments (5), and the set associated with the first security element (3) and the set associated with at least the second security element (4) differ in at least one data segment; wherein the photoelectrically discernible defined area includes the first security element (3) and at least the second security element (4), The method comprises the following steps: capturing a first image (12) of the object marker (9) from a first angle (10) or under a first lighting direction; identifying a first code segment presented by the first security element (3) in the first image (12); Decoding the first code segment to obtain a first data segment; capturing a second image (17) of the object marker (9) from a second angle (10) different from the first angle (10) and / or at a second lighting direction different from the first lighting direction; identifying a second code segment presented by the first security element (3) in the second image (17); decoding the second code segment to obtain a second data segment; determining whether there is a data segment set including the first data segment and the second data segment based on a model (16) storing the data segment set (6, 7) associated with the security elements (3, 4) of the base material (1) and storing the relative positions of the security elements (3, 4) of the base material (1) to each other; identifying a third code segment presented by the second security element (4) in the first image (12) or the second image (17); decoding the third code segment to obtain a third data segment; Determine whether the second security element (4) positioned relative to the first security element (3) is associated with the data segment set containing the third data segment based on the model (16) storing the data segment set associated with the security elements (2) of the base material (1) and storing the relative positions of the security elements (2) of the base material (1) to each other.

2. The method according to claim 1, wherein: Each security element (3, 4) presents, depending on the viewing angle (10) and / or the lighting direction, said code segment (5), which is an electro-optically readable representation of one of the data segments of said set associated with said respective security element (3, 4).

3. The method according to any one of claims 1 or 2, wherein: The security elements (2) of the base material (1) of which the object mark (9) comprises a part are arranged in a tiled manner, and each code segment (5) presented by the security element (2) is a tile array, and the code segment (5) presented by one security element is arranged to have a spreading property with respect to the code segments presented by other security elements, so as to form a larger tile array, and the method is characterized in that the method further comprises the following steps: a) identifying a first sample block (11) in the first image; b) decoding a first sample code segment (13) in the first image (12) to obtain a first sample data segment (15), the first sample code segment (13) being formed by a first sample tile array including the first sample tile (11) at a predefined position; c) determining, based on the model (16) storing the sets of data segments associated with the security element (2) of the base material (1), whether there is at least one set of data segments containing the first sample data segment (15); d) if such a set cannot be determined in step c), repeating steps a) to c) using different first sample tiles until such a set is found in step c); and 1) Identifying the current first sample code segment (13) as the first code segment.

4. The method according to claim 3, characterized in that The method further comprises the following steps before step 1): e) identifying the first sample tile (11) in the second image (17); f) decoding a second sample code segment (18) formed by the first sample tile array in the second image (17) to obtain a second sample data segment (19); g) determining, based on the model (16) storing the sets of data segments associated with the security element (2) of the base material (1), whether at least one of the at least one sets containing the first sample data segment (15) contains the second sample data segment (19); h) if no such set can be determined in step g), repeating steps a) to g) until such a set is found in step g); and m) identifying the current second sample code segment as the second code segment.

5. The method according to claim 3, characterized in that: The method further comprises the following steps before step 1): i) decoding a third sample code segment (20) formed by a second sample tile array positioned relative to said first sample tile array to obtain a third sample data segment (22); j) determining, based on the model (16) storing the set of data segments associated with the security elements (2) of the base material (1) and storing the relative positions of the security elements (2) of the base material (1), whether the third sample data segment (22) is included in the following set of data segments: the set of data segments belongs to the security elements respectively positioned relative to the security elements to which the set preliminarily identified in step e) belongs; k) if no such set can be determined in step j), repeating steps a) to d) and steps i) to j) until such a set is found in step j); n) identifying the current third sample code segment as the third code segment.

6. The method according to claim 4, characterized in that The method further comprises the following steps before step 1) and before step m): i) decoding a third sample code segment (20) formed by a second sample tile array positioned relative to said first sample tile array to obtain a third sample data segment (22); j) determining, based on the model (16) storing the set of data segments associated with the security elements (2) of the base material (1) and storing the relative positions of the security elements (2) of the base material (1), whether the third sample data segment (22) is included in the following set of data segments: the set of data segments belongs to the security elements respectively positioned relative to the security elements to which the set preliminarily identified in step e) belongs; k) if no such set can be determined in step j), repeating steps a) to d) and steps i) to j) until such a set is found in step j); n) identifying the current third sample code segment as the third code segment.

7. The method according to claim 6, characterized in that: In step k), if no such set can be determined in step j), steps a) to d) and steps i) to j) and steps e) to h) are repeated until such a set is found in step j).

8. The method according to claim 4, characterized in that The method further comprises the following steps before step 1): i) decoding a third sample code segment (20) formed by a second sample tile array positioned relative to said first sample tile array to obtain a third sample data segment (22); j) determining, based on the model (16) storing the set of data segments associated with the security elements (2) of the base material (1) and storing the relative positions of the security elements (2) of the base material (1), whether the third sample data segment (22) is included in the following set of data segments: the set of data segments belongs to the security elements respectively positioned relative to the security elements to which the set preliminarily identified in step e) belongs; k) if no such set can be determined in step j), repeating steps a) to d) and steps i) to j) and steps e) to h) until such a set is found in step j); n) identifying the current third sample code segment as the third code segment.

9. A method for generating an object label (9), the method comprising the following steps: randomly, pseudo-randomly or deterministically selecting a region of the base material (1), Wherein, the basic materials include: a first security element (3) and at least a second security element (4), wherein each security element (3, 4) is associated with a set of data segments and each security element (3, 4) presents a code segment (5) according to a capture condition, said code segment being an electro-optically readable representation of one of the data segments of said set associated with the respective security element (3, 4), wherein different distinct data segments are represented by different code segments (5), and The set associated with the first security element (3) and the set associated with at least the second security element (4) differ in at least one data segment; The selected area includes the first security element (3) and at least the second security element (4), optoelectronically distinguishing the selected region from unselected portions of the base material (1), and The set of data segments associated with the security elements (3, 4) of the base material (1) and the relative positions of the security elements (3, 4) of the base material (1) are stored in the model, so that the set of data segments associated with the security elements (3, 4) of the base material (1) and the relative positions of the security elements (3, 4) of the base material (1) can be accessed by a programmable device during verification of the object tag (9).

10. The method according to claim 9, wherein: The base material comprises a sufficient number of security elements (3, 4) to produce at least two object markings (9).

11. The method according to any one of claims 9 or 10, wherein: The base material comprises a two-dimensional array of at least 5×5 security elements (3, 4).

12. The method according to any one of claims 9 to 10, wherein: The base material has a repeating sequence of security elements (3, 4), wherein the repeating period is greater than the size of a single object marking (9).

13. The method according to any one of claims 9 to 10, wherein: The regions of the base material (1) are selected randomly or pseudo-randomly.

14. The method according to any one of claims 9 to 10, wherein: Each security element (3, 4) of the base material (1) presents, depending on the viewing angle (10) and / or the lighting direction, a code segment (5), which is an electro-optically readable representation of one of the data segments of the set associated with the respective security element (3, 4).

15. The method according to any one of claims 9 to 10, wherein: Under at least one defined capture condition, each code segment representing in an optoelectronically readable manner a data segment (6, 7) of the set of data segments (6, 7) associated with each security element (3, 4) is presented by the security element (3, 4).

16. The method according to any one of claims 9 to 10, wherein: Each code segment (5) represents the corresponding data segment in a predefined encoding.

17. The method according to claim 16, wherein: The predefined code includes information for error detection or error correction.

18. The method according to claim 16, wherein: The predefined encoding allows a maximum number of possible distinct data segments, and the number of distinct data segments in the set of data segments of all security elements is less than 1 / 100 of the maximum number of possible distinct data segments.

19. The method according to claim 18, wherein: The number of distinct data segments in the set of data segments of all security elements is less than 1 / 1000 of the maximum number of possible distinct data segments.

20. The method according to claim 18, wherein: The number of distinct data segments in the set of data segments of all security elements is less than 1 / 10000 of the maximum number of possible distinct data segments.

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