CN111989721B - Method for verifying security features based on luminescent materials - Google Patents
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- G—PHYSICS
- G07—CHECKING-DEVICES
- G07D—HANDLING OF COINS OR VALUABLE PAPERS, e.g. TESTING, SORTING BY DENOMINATIONS, COUNTING, DISPENSING, CHANGING OR DEPOSITING
- G07D7/00—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency
- G07D7/06—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency using wave or particle radiation
- G07D7/12—Visible light, infrared or ultraviolet radiation
- G07D7/1205—Testing spectral properties
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- G—PHYSICS
- G07—CHECKING-DEVICES
- G07D—HANDLING OF COINS OR VALUABLE PAPERS, e.g. TESTING, SORTING BY DENOMINATIONS, COUNTING, DISPENSING, CHANGING OR DEPOSITING
- G07D7/00—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency
- G07D7/20—Testing patterns thereon
- G07D7/2008—Testing patterns thereon using pre-processing, e.g. de-blurring, averaging, normalisation or rotation
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- G—PHYSICS
- G07—CHECKING-DEVICES
- G07D—HANDLING OF COINS OR VALUABLE PAPERS, e.g. TESTING, SORTING BY DENOMINATIONS, COUNTING, DISPENSING, CHANGING OR DEPOSITING
- G07D7/00—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency
- G07D7/20—Testing patterns thereon
- G07D7/2016—Testing patterns thereon using feature extraction, e.g. segmentation, edge detection or Hough-transformation
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- G—PHYSICS
- G07—CHECKING-DEVICES
- G07D—HANDLING OF COINS OR VALUABLE PAPERS, e.g. TESTING, SORTING BY DENOMINATIONS, COUNTING, DISPENSING, CHANGING OR DEPOSITING
- G07D7/00—Testing specially adapted to determine the identity or genuineness of valuable papers or for segregating those which are unacceptable, e.g. banknotes that are alien to a currency
- G07D7/20—Testing patterns thereon
- G07D7/202—Testing patterns thereon using pattern matching
- G07D7/205—Matching spectral properties
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- Investigating, Analyzing Materials By Fluorescence Or Luminescence (AREA)
Abstract
The present invention relates to a method for verifying a luminescent material based security feature by a smart phone, the security feature comprising a luminescent material that can be excited to radiate. In a first step, the luminescent material of the security feature is excited to radiate by the lighting unit of the smartphone. During a predetermined decay time after the end of the excitation, the radiation is detected by capturing a sequence of images or video with an image detection unit of the smartphone. Finally, the image sequence or video is evaluated by means of a data processing unit of the smart phone, wherein the radiation detected during the decay time is compared with stored reference data to verify the authenticity of the security feature.
Description
Technical Field
The present invention relates to a method for verifying a security feature.
Background
It has long been known from the prior art to provide security documents with security features in the form of luminescent substances in order to render them tamper-proof or verifiable. Such security features must be verified by suitable means.
An instrument for authenticating documents marked with a photochromic system is known from WO 2012/083469 A1. The photochromic security feature exhibits a color change and/or a shape change upon flash excitation. Also described are security features constructed based on retinal proteins.
WO 2013/034471 A1 describes an instrument for identifying documents having security features with wavelength conversion characteristics. For this purpose, a light-emitting device is provided, which emits a security feature with excitation light, and an image capture device is provided, which receives the light emitted by the security feature.
WO 2013/034603 A1 describes a method for verifying a security document having a security feature in the form of a fluorescent printing element. The method provides that the printing element is excited by means of a light source and thereby emits electromagnetic radiation, which is detected in a further step by a sensor. The detected data is evaluated by comparison with the given data. And outputting a verification result in a further step according to the comparison result. In particular, the method will be implemented in a smart phone, wherein a flash module of the smart phone is used as an excitation source and a light sensor of a camera of the smart phone is used as a detection unit.
A multifunctional mobile device is known from US 2010/0144387 A1. The apparatus includes a camera module, a processor unit, and a display.
Two heretofore unsolved problems arise in the verification of luminescent material based security features described in the above prior art. Previously known luminescent materials are often used as so-called conversion luminescent materials for producing white LEDs, such that these luminescent materials are also often contained within flash LEDs of camera units (cameras) of smartphones and similar mobile devices. If it is desired to use such a device to provide excitation radiation for verification of a security feature, the excitation source presents the same radiation as the security feature to be checked, so that reliable verification is not possible. The second problem is caused by the fact that the luminescent materials described in the prior art have a very short decay time in the range of ns to mus. Since the camera of a mobile device typically has a relatively low shooting speed (modern advanced smartphones up to 240 fps), when excited with a smartphone flash, the radiation originating from the security feature is usually already attenuated before the camera of the smartphone can be used for image shooting after the excitation has ended.
According to the level of knowledge before the present invention, experts consider that luminescent material based security features are hardly suitable for simple performing verification in daylight while meeting relatively high security requirements, as they cannot be verified at low cost and using a wide range of devices. The known security features require very special verification devices that are available only in larger units, such as banks or transit checkpoint prescriptions. Or security features that can be verified with generally available devices, such as smartphones in particular, are susceptible to counterfeiting.
Disclosure of Invention
It is therefore an object of the present invention to provide an improved method for verifying a luminescent material based security feature. In particular, the security feature should be detectable by the image capturing unit of the smartphone and also be verifiable by the data processing unit of the smartphone. Particularly at the time of verification, not only the presence of the radiation but also the specific characteristics of the radiation should be checked.
According to the invention, this object is achieved by a method for verifying a security feature based on a luminescent material, the security feature comprising a luminescent material capable of being excited to emit light, the luminescent material having a decay time in the ms range, the method comprising the steps of: exciting the luminescent material of the security feature by the lighting unit of the smart phone to radiate the luminescent material; detecting radiation by capturing an image sequence or video with an image detection unit of the smartphone during a predetermined decay time after the excitation is over; the image sequence or video is evaluated by means of a data processing unit of the smartphone, wherein the radiation detected during the decay time is compared with stored reference data to verify the authenticity of the security feature.
The general solution proposed for the task, which is adopted by the present invention, consists firstly in providing the security feature with a specific luminescent material which circumvents the above-mentioned problems. The luminescent material must for this purpose be configured such that it can be excited on the one hand with the light source of a smart phone or of such a mobile data processing device, and thus in particular with the flash LED of the smart phone. At the same time, the luminescent material must have a luminescence characteristic (luminescence yield, decay time) that enables a reliably detectable decaying luminescence signal even after the end of the flash excitation. The decay time and the radiation occurring during decay must be distinguishable from the other luminescent material, and furthermore the decaying luminescent signal should not be perceptible to human vision. This indicates that this condition is met by only a few specifically configured luminescent materials that can be used in the security feature. Such luminescent materials must in particular have decay times in the ms range. Suitable luminescent materials are given in german patent application DE 10 2018 109 141.9 entitled "smart phone verifiable security features based on luminescent materials and means for verification" filed by the applicant at the same priority date (date 2017, month 4, 17). The content of this further patent application, in particular with respect to the composition and manufacture of luminescent materials usable therein, is fully and completely incorporated into the disclosure of the present invention.
The method according to the invention is used to verify a luminescent material-based security feature that can be excited to emit light, which security feature is arranged on a security document. The method may be implemented by means of a smartphone or similar mobile terminal device which is correspondingly configured and controlled by software, preferably in the form of an App.
The security feature which can be evaluated by the method according to the invention is applied to or incorporated into a security document and comprises the luminescent material described above. The luminescent material may be excited to emit light by electromagnetic radiation of a predetermined wavelength, followed by the emission of radiation. The decay time of the emission of the luminescent material is in the range of ms. The decay time is preferably selected in the range between 1ms and 100ms, particularly preferably in the range between 5ms and 50ms, again preferably in the range between 10ms and 30 ms. Furthermore, the radiation of the luminescent material may be detected by means of an image detection unit of the smart phone.
In a first method step, the security document is positioned such that the security feature is detected by the image capturing unit of the smartphone. In the simplest case, this is done by manually positioning the security document in front of the image capturing unit. Preferably, a translucent mask or a positioning frame is shown in the display of the mobile terminal device as user support. An identification that is visually perceptible to a person and is positioned within the positioning frame may be applied to the security document. The security feature is then placed in proximity to this tag such that the tag is located within the detection area of the image detection unit.
Alternatively, the object recognition may be performed by means of an image detection unit and a data processing unit of a smart phone (mobile terminal device). Object recognition is indirectly used to determine the location of security features on a document and/or to support the positioning of a smartphone over a security document. Object recognition may also be used for automatic triggering of detection.
In an optional method step, a camera frame or a camera window is specified, wherein its positioning is defined in accordance with a previously determined positioning of the security feature, and wherein the camera frame is selected such that the security feature is arranged in the region of the camera frame.
In a subsequent method step, the security feature is excited to emit light by means of a lighting unit of the smart phone (mobile terminal device), so that the security feature emits electromagnetic radiation. The illumination unit and the image capturing unit are controlled by a data processing unit of the smartphone by means of an App (software application), wherein a combination of single flash and video capturing or a combination of single flash and serial capturing is performed, and wherein the illumination unit is turned off after the luminescent material of the security feature is excited, so that after the end of the flash, attenuated radiation can be captured by the image capturing unit.
An optional method step provides for defining a reference region directly adjacent to the security feature. The evaluation of the images of the detected security features and of the reference areas and the evaluation of the differences detected here (image differences, histograms, hue values) may be helpful for document verification in the case of intense flashing external light.
In a further method step, an image sequence or video of the security feature and optionally of the reference region is recorded by an image detection unit of the smart phone for detecting radiation. The recording is preferably carried out in a defined recording region. Radiation is detected after the excitation is over, i.e. after the flash is turned off. Preferably, the time of capture of the image sequence or of the video captured by the image detection unit is selected such that the radiation of the security feature can no longer be detected in the last image of the image sequence or of the video as long as the predetermined decay time of the luminescent material of the security feature ceases. This last image is taken as a reference image (B Reference to ). Also, a starting image may optionally be taken before the luminescent material is excited, which starting image may be employed in the verification as a further reference.
In a further method step, the detected or captured image sequence or video is processed by a data processing unit and compared with predetermined data or reference data. In the simplest case, the reference data is stored in the smartphone, and then the reference data is compared with the known radiation parameters.
Preferably, an image difference (delta) between the detected image and a reference image detected after radiation decay is generated 1R ＝B 1 -B Reference to …Δ nR ＝B n -B Reference to ) From which radial values are then calculated as channels of different colours by means of RGB histogramsHue values, and then analyzing the decay time of the luminescent material based on the learned data. Preferably, n=10 images are used to calculate the image difference. The number of images is preferably between 5 and 15 images.
Assuming exponential decay behavior, the decay time (τ) may be determined by the following equation:
Where Δt is the time interval between images, and E (t) is the emission value at the determined instant of decay.
These values may be known from the histogram of the image or the image differences.
The spectral distribution of the emission of the luminescent material can be known from the color coordinates of the different images, wherein:
Furthermore, a comparison of the additional starting image recorded before the activation of the excitation radiation with the image of the image sequence recorded during the decay time and with the last image (reference image) can be carried out.
By comparison, the presence of the security feature in the region of the camera frame can be verified and the authenticity of the security document can then be verified. In particular, by verifying the security features on the security document, the authenticity and integrity of the security document can be verified.
The reference image is the last image in the image sequence, which is generated within a predetermined time range, in particular within the ms range, so that radiation having a decay time greater than the ms range is also filtered out. For this purpose, the reference image can be compared with a starting image recorded before the activation of the excitation radiation.
In one embodiment of the method, the authenticity of the security feature is verified according to the following features:
-comparing the last image (reference image) in the series of photographs with the starting image taken before the excitation, with reference to a ping;
-detecting a security feature, and
-determining a radiation characterization (τ, λ) of the security feature or its luminescent material.
The speed of the imaging when producing the image sequence is chosen such that the fluorescent material or the features with a short decay time, i.e. in the range of mus, are inferred to be unverified, since such short radiation cannot be detected with sufficient intensity. By referring to the inspection in which the last image in the photograph is compared with the starting image taken before excitation, the luminescent material with a long decay time is inferred to be unverified. If one of the two features indicates a fluorescent or phosphorescent material, the result of the authenticity of the security feature is output as "false".
In addition to verifying the presence of the luminescent material sought within the security feature, the external shape of the security feature may also be verified. If the detected luminescent material and security feature do not match the stored data of the predetermined luminescent material or security feature, then the authenticity is determined to be "false". For the features of the radiological characterization, the spectral distribution of the radiation emitted by the luminescent material and the decay time of the luminescent material of the security feature are examined. If the spectral position and decay time of the luminescent material agree with the stored values and if the other features are still confirmed to be positive ("true"), a verification is made that the security feature is "true".
The optional object recognition preferably comprises different image processing steps, such as filter applications for noise reduction, contrast matching or color channel enhancement, shape analysis for detecting security features. The noise reduction may be performed, for example, by means of a morphological filter, for example, by erosion or dilation. Template matching may be used for shape analysis. A Fast Fourier Transform (FFT) of the image may also be used.
In a preferred method step, which is particularly interesting in strong ambient light, the distance between the security document with the security feature and the image detection unit of the smartphone is selected to be less than or equal to the distance of the focusing area of the image detection unit. No optical focusing or focusing adjustment is required. Since no sharp image is required for the present method, the distance between the smartphone camera and the security feature can be chosen to be small when detecting the image, since only the radiation of the security feature and, if necessary, the shape of the security feature is detected. An advantage of the small distance between the security feature and the camera is that more energy is available to excite the luminescent material of the security feature and detect the emission of the luminescent material over a wide spatial angle. Minimizing the distance between the camera and the security feature is particularly important due to the quadratic dependence of the intensity of the flash light and the distance to the excitation source or the quadratic dependence of the radiation and the distance to the detection unit. Thus, radiation that is relatively low and no longer detectable when captured in the focus area can also be detected. This reduces the false reject rate (i.e. the authentic security document is rated as false). For example, a typical smart phone has a 60mm focus area. Thus, for the method, a distance between 10mm and 80mm between the image detection unit and the security document with the security feature is preferably used for taking the image. The distance between the image capturing unit and the security document with the security feature is particularly preferably less than 50mm during image capturing. Another advantage of using blurred images is that the resolution of the images is reduced and thus the processing of the images is speeded up.
In a further embodiment of the method for authenticating a security feature, the reference area is selected to be beside the area of the security feature, i.e. beside the area of the luminescent material. The two areas preferably have the same visible surface color. Therefore, it can be used to compensate for exposure fluctuations during shooting under artificial light (50 Hz flicker). Preferably, the positioning of the luminescent material and the reference area on the security document is predefined (e.g. relative to a special symbol on the document). For verification, an equal number of pixels are selected in both areas of all detected images, and an image difference is created for these parts for each image.
For certain luminescent materials, in particular silicate garnet, additional verification factors may be used. These luminescent materials exhibit broad emission spectra with local maxima in the green and red spectral ranges and, furthermore, have different decay times. It follows that the color shift of the characterization is ascertained when the attenuation is measured over the entire visible spectrum, which can also be used as a plausibility criterion.
Another advantage of the method is that a large number of users can use the known smart phone as a mobile terminal device to verify the security features. A rapid, internal evaluation and verification of the luminescent material emissions measured with a smart phone is performed. It is furthermore advantageous that the distance between the security feature and the image capturing unit can be kept small, since the security feature is simultaneously shielded from ambient light, such as daylight or room light.
The method and its method steps are preferably provided as an application or App of a smart phone.
The image frequency of the image sensor used, in particular a smartphone camera, determines the lower limit achievable by the decay behavior of the luminescent material.
The upper limit is predetermined by the physiological characteristics of human vision, in particular by visual perception, i.e. the reception and processing of optical stimuli by the eyes and brain. In order to be able to assign the luminescent material used in the security feature to a high security level, no radiation of the security feature should be detected by human visual perception. In particular, the decay time of the luminescent material should be less than 1s, since the afterglow of the luminescent material is perceivable by a human from 1 s. The light-emitting material is selected so that the decay time is in the range of several ms or several tens ms. The decay time of the luminescent material of the security feature (always considered from the point of view of switching off the excitation source) is preferably in the range of 1ms to 50 ms. The luminescent material of the security feature particularly preferably has a decay time of 10ms to 30 ms.
In order to make the security feature detectable only by the mobile terminal device, in particular the smart phone, the luminescent material is configured such that it can be excited in the visible spectral range, in particular in the blue spectral range, so that the flash light source of the smart phone can emit this excitation radiation. Furthermore, the luminescent material is configured such that it emits in the visible spectrum, wherein the user cannot detect this emission by visual perception due to the short decay time.
The white light of the lighting unit of a smartphone is produced by an LED consisting of an LED semiconductor chip with an emission wavelength of approximately 450nm and an LED conversion luminescent material arranged above the LED semiconductor chip, wherein the conversion luminescent material converts the emission of the blue LED in portions into visible luminescent radiation with a maximum peak emission of approximately 560nm (broadband emission in the green, yellow and red spectral ranges.
The smart phone camera may be used as an image detection unit to detect a light emitting signal of a light emitting material. The image detection unit is preferably a CMOS sensor equipped with an IR filter, whereby the spectral sensitivity is up to about 750nm. A single image, sequence of images or video may be acquired by the image detection unit.
In principle, the method according to the invention can be used in different examination devices. The verification device may be used as a retrofit module for stationary verification (for example in an automated teller machine) or preferably be designed as a mobile terminal device. The mobile terminal device is preferably a smart phone, but may also be a tablet computer or other similar multifunctional data processing device comprising a camera with an image detection unit and/or a lighting unit and comprising a data processing unit. The data processing unit is preferably a processor, in particular a microprocessor. The verification may also be performed using a stationary terminal device or other data processing system with an image detection unit, such as a desktop display or a service terminal.
The luminescent material is preferably arranged in a patterned manner within the security feature. The luminescent material, in particular luminescent pigment of the luminescent material, is preferably applied as a defined pattern on the carrier. The pattern may be arranged in a triangular or star shape, for example. Alternatively, the pattern of security features formed from luminescent material may contain data and be arranged as a code, for example a QR code.
Pigments of luminescent material are printed as security features, for example, on security documents or on layers of security documents. The printing or application of the luminescent material on the security document may be performed by known printing methods, such as gravure, flexography, offset printing, screen printing or digital printing methods. Furthermore, the luminescent material may be applied to the security document by a coating method or a lamination method.
A plausibility check and/or an integrity check may be performed. The security feature must be verified by selecting the luminescent material whose decay time is in the ms range. It has proven advantageous to select the luminescent material in such a way that the emission of the luminescent material can be reliably measured even after the end of the excitation process. The luminescent material can be verified not only by decay time and emission spectrum, but also as an additional safety factor the pattern formed by the luminescent material. Thus, a high security against counterfeiting can be achieved by a combination of factors. For more reliable authentication of a security document with a security feature, this security feature may be arranged, for example, in the region of a further security feature, for example in the region of an image.
The security features may be applied to different security documents, such as banknotes, identification cards, passports, driver's licenses, tickets, stamps, and the like.
Drawings
Further details, advantages and improvements of the invention emerge from the following description of a preferred embodiment of the invention with reference to the accompanying drawings. Wherein:
figure 1 shows an embodiment of a security feature according to the invention on a banknote;
FIG. 2 shows a schematic illustration of components of a facility for verifying a security feature in accordance with the present invention;
FIG. 3 shows a schematic representation of the appearance and decay behavior of the luminescent material of the security feature upon flash excitation;
fig. 4 shows a flow chart of performing security feature verification with a facility according to the invention.
Detailed Description
Fig. 1 shows a security feature 01 according to the invention, which security feature 01 is applied to a value document, namely a security document 02 in the form of a banknote, which is illustrated symbolically. The security feature may be used to authenticate the security document 02. The security feature 01 here has a star shape. The security feature 01 is positioned under the visible feature 03 (here the denomination of the banknote). The security feature 01 consists of a luminescent material capable of exciting luminescence by electromagnetic radiation with a predetermined wavelength, as described above, and explained in detail in the further patent applications of the cited applicant.
The security feature 01 may be verified by a method in which the authenticity of the security feature 01 is verified.
Fig. 2 shows a schematic illustration of a device for verifying a security feature 01, wherein the security feature 01 is excited to emit light by means of an illumination unit 04 of an image recording unit 06 of a mobile terminal, in particular of a smart phone 07, in such a way that the illumination unit 04 generates excitation light, in particular a flash 08. The flash 08 of the image detection unit 06 is generated by an LED emitting white light. Flash 08 has intensity I A . After excitation, the luminescent material of the security feature 01 emits electromagnetic radiation, which occurs within a decay time in the ms range after the excitation has ended. The radiation I of the luminescent material can be detected using the detector 09 or camera of the image capturing unit 06 E . In addition, the detector 09 detects the security feature 01 and the banknoteAmbient radiation I of sunlight or indoor light on ticket 02 and reflected here 0 . In the method according to the invention, the environmental radiation I can be kept small, since the distance d between the security feature 01 and the smart phone 07 can be kept small 0 Kept low. Due to the small distance d, which is preferably smaller than the focusing area (focal point) of the image capturing unit 06, the smartphone 07 is largely shielded from the ambient radiation I 0 。
Fig. 3 shows a graph of the appearance and decay behavior of a luminescent material used within security feature 01. In this graph, the emission curve 11 of the excited luminescence security feature 01 is illustrated along the time axis t. Furthermore, a flash excitation curve 12 is plotted along the time axis. If a flash is generated by the smartphone 07 (fig. 2), the flash excitation curve 12 rises steeply, keeps its level for a short time, and extinguishes after the flash. The luminescent material of the security feature 01 is stimulated to emit light by the electromagnetic radiation of the flash of light, whereby its emission curve 11 rises almost simultaneously with the flash emission curve 12, typically with a decreasing slope. After the flash is extinguished, the emission curve 11 drops significantly more slowly than the flash excitation curve. According to the invention, the decay behavior of the luminescent material is in the range of ms.
Below the time axis in fig. 3, the respective images 13 of the security feature 01 detected by the detector 09 of the smart phone 07 (fig. 2) are shown. The image acquisition 13 shows the attenuated radiation of the security feature 01 as a pattern that weakens over time. The pattern may be used in a further processing step for verification of the security document 02. After substantially complete attenuation of the radiation, the reference image 14b can be detected as the last image of the captured image sequence. Depending on the evaluation method, an additional reference image 14a may also be recorded before the excitation radiation is activated (triggering a flash). For example, by comparing reference images 14a and 14b to each other, additional checks may be made for security features.
Fig. 4 shows in simplified form a principle sequence for verifying the security feature 01 by using the facility illustrated in fig. 3. In a positioning step 41, the security document to be verified is positioned so that it can be reliably detected by the image detection unit of the smartphone. In an optional reference verification step 42, the starting image 14a of the security feature is generated before triggering the flash activation of the smartphone. In a detection step 43, a single flash is triggered by means of the image capturing unit and the illumination unit of the smartphone and an image sequence capturing or video capturing is performed to record the luminescence signal present after the end of the flash excitation and decaying in the ms range for the luminescent material used to create the security feature. Finally, in a radioanalysis step 44, the sequence of images taken is compared with a reference photograph by means of a data processing unit. In addition to calculating the image differences and their analysis, other image processing methods (e.g. contrast matching and histogram analysis of different color channels) can also be used here to verify in this way the radiological characterization of the spectrum of the luminescent material used according to the invention and its proprietary decay characterization. Object recognition may be implemented in an optional extraction step. By comparing the calculated parameters with the authenticity parameters of the security features preferably stored in the data memory of the smartphone, the authenticity of the inspected security document can be confirmed in a release step 45. In particular, by verifying the security features on the security document, the authenticity and integrity of the security document can be confirmed.
List of reference numerals
01. Security feature
02. Security document/banknote
03. Denomination of face
04. Lighting unit
05 -
06. Image capturing unit
07. Smart phone
08. Flash light
09. Detector/camera
10
11. Radiation profile
12. Flash excitation curve
13. Image photograph of security feature 01
14a initial image
14b reference image
41-45 method steps
Claims (8)
1. A method for authenticating a luminescent material based security feature by a smart phone, the security feature comprising a luminescent material capable of being excited to emit, the luminescent material having an decay time in the ms range, the method comprising the steps of:
-exciting the luminescent material of the security feature by the lighting unit of the smartphone to radiate it;
-detecting radiation by capturing a sequence of images or video with an image detection unit of the smartphone during a predetermined decay time after the end of excitation;
evaluating the image sequence or video by means of a data processing unit of the smartphone, wherein radiation detected during an decay time is compared with stored reference data to verify the authenticity of the security feature,
and wherein a distance between the security feature and an image detection unit of the smartphone is selected to be less than a focus area of the image detection unit during excitation of the luminescent material and during detection of radiation.
2. The method according to claim 1, characterized in that for evaluating the image sequence the following radiological characterization is known: decay time, wavelength, and/or color shift, and comparing the radiation characterization to the reference data.
3. A method according to claim 1 or 2, characterized in that for detecting radiation an image difference, Δ, between the image taken during the decay time and a reference image detected after the decay of the radiation is generated 1R ＝B 1 -B Reference to …Δ nR ＝B n -B Reference to And then calculating the radial value as hue values of different color channels through RGB histogram, and then determining the decay time of the luminous material.
4. The method according to claim 1 or 2, characterized in that the following steps are performed before the excitation of the luminescent material:
-performing object recognition by means of an image detection unit and a data processing unit of the smartphone to determine a positioning of the security feature on a security document or to correspond to a predetermined positioning frame displayed in a display of the smartphone and to position the smartphone on the security document according to a positioning mark of the security document, the positioning frame being arranged above the positioning mark;
-defining a camera frame according to the determined positioning of the security feature, wherein the security feature is arranged within an area of the camera frame;
-defining a reference area, said reference area being arranged directly adjacent to said photographing frame;
and after the excitation has ended, a detection of the image sequence takes place in the region of the acquisition frame and in the reference region.
5. The method according to claim 4, characterized in that the sequence of images detected in the shooting frame is compared with the sequence of images detected in the reference area by the data processing unit.
6. A method according to claim 1 or 2, characterized in that the time of capture is chosen such that the last image of the sequence of images is captured after the end of the decay time and the security feature is verified as true only if no radiation of the luminescent material can be detected in the last image.
7. The method according to claim 6, characterized in that the comparison of one or more images of the image sequence of the positioning frame with the last image of the image sequence by the data processing unit of the smartphone is performed in the following sub-steps:
-radiation identification, wherein the image difference of the detected image and the reference image is known separately, an RGB histogram is created, the hue values of the different color channels are known, and the decay time of the luminescent material is known; and
-object recognition, wherein a shape analysis of the security feature is performed.
8. Method according to claim 1 or 2, characterized in that an application is installed on a mobile terminal device, which controls the lighting unit, the image detection unit and the data processing unit for implementing the method.
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DE102018109142.7 | 2018-04-17 | ||
| DE102018109142.7A DE102018109142A1 (en) | 2018-04-17 | 2018-04-17 | Method for verifying a fluorescent-based security feature |
| PCT/EP2019/059635 WO2019201839A1 (en) | 2018-04-17 | 2019-04-15 | Method for the verification of a luminescent-material-based security feature |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN111989721A CN111989721A (en) | 2020-11-24 |
| CN111989721B true CN111989721B (en) | 2023-07-14 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201980026799.2A Active CN111989721B (en) | 2018-04-17 | 2019-04-15 | Method for verifying security features based on luminescent materials |
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| Country | Link |
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| EP (1) | EP3782136B1 (en) |
| CN (1) | CN111989721B (en) |
| DE (1) | DE102018109142A1 (en) |
| WO (1) | WO2019201839A1 (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE102020104115A1 (en) * | 2020-02-17 | 2021-08-19 | Bundesdruckerei Gmbh | Method for checking a smartphone-verifiable security feature, smartphone-verifiable security feature and value or security document |
| DE102020120567B4 (en) | 2020-08-04 | 2022-07-14 | Bundesdruckerei Gmbh | PROCEDURE FOR VERIFICATION OF THE AUTHENTICITY OF A FLUORESCENT SECURITY FEATURE USING A MOBILE DEVICE AND MOBILE DEVICE |
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Also Published As
| Publication number | Publication date |
|---|---|
| DE102018109142A1 (en) | 2019-10-17 |
| EP3782136A1 (en) | 2021-02-24 |
| WO2019201839A1 (en) | 2019-10-24 |
| EP3782136B1 (en) | 2023-07-26 |
| CN111989721A (en) | 2020-11-24 |
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