EP3922474A1 - Method for verifying the authenticity of an image printed on a carrier for a security or value document - Google Patents

Abstract

The invention relates to a method for checking the authenticity of a visible image (15) printed on a data carrier (20) and encoded with detectable image-specific results (12), image-specific results (12e) to be expected being calculated from the visible image (15) and then their correspondence with the image-specific results (12) encoded in the image (15) or in the area (25) of the layer (27) above the image (15) is checked.

Description

The invention relates to a method for checking the authenticity of an image printed on a carrier for a security or value document and the production of the printed image on the data carrier which is protected against forgery.

Security documents such as ID cards or driver's licenses generally have photographs as a security feature. When producing ID documents, the data from the digital photos are processed using the Raster Imaging Process (RIP). The image visible in the security document is printed with colored inks in the three standardized optimal colors cyan, magenta, yellow and possibly black.

In order to detect manipulation of the photos, it is customary to provide photos with security features, which can be provided, for example, in a zone in the image to be applied.

Security documents are among other things. forged by applying a photo of another person over the photo of the document holder.

The photo of the other person can be applied directly, for example, by printing the actual photo directly onto the card surface using an inkjet printing process, or indirectly by first printing on a transfer film and then laminating the image over the actual photo . Particularly good forgeries leave the other security features such as luminescent negative pressure or kinematic holographic structures (Identigram) largely intact, so that the document looks virtually unmanipulated or a little aged.

Tampering with photos of real documents to generate false identities is therefore an increasing risk.

the US 2003/0173406 A1 teaches a security document with a visible image and a digital one that is only visible under UV radiation enhanced ghosting that may be incorporated into the same image.

From the DE 600 04 529 T2 there are known security documents with visible and personalized invisible markings that cannot be seen without the involvement of an external factor.

the DE 696 24 400 T2 relates to security documents having a printed image and a compressed digital image encoded in the magnetic medium of the image.

the DE 697 11 482 T2 teaches a certificate bearing an image engraved in an engraving film.

From the U.S. 5,421,619 a security document is known with a photo of the owner and a dithered image of the photo introduced with a laser.

the DE 10 2006 052 651 A1 relates to a data carrier with a first graphic representation and a second graphic representation, which is better protected against manipulation and is designed as a reference for determining tampering with the first representation, only partial areas of the first and second representation overlapping.

From the EP 2 209 653 B1 processes for the production of polymer layer composites for security and value documents are known.

The invention is based on the object of specifying a method for recognizing manipulations on the security and value documents.

This object is achieved by the features of claims 1 and 2. In the method according to the invention for checking the authenticity of a visible image printed on a data carrier that is coded with detectable image-specific results, image-specific results to be expected are calculated from the visible image and then their correspondence with in the image or in the area of the layer above the Image-coded image-specific results are checked.

Image-specific results are calculated from the data of a digital image and the visible, printed image or an area of at least one layer of the data carrier above the image is encoded with these results in a detectable form.

Since the visible image itself is coded with the image-specific results or the area of a layer above the image and the coding is detectable, the authenticity of the image can be checked solely on the basis of the image and possibly the layer area of the data carrier above the image.

The coding can be visible or invisible in visible light. An invisible coding has the advantage that it is not easily recognizable for the forger. In principle, the coding can take place in the visible image at the same time as the printing of the visible image, but also before or after the printing of the visible image.

Insofar as the coding is not in the image itself, but in an area in one or more layers above, ie above the image, i.e. either in an area of a layer of the data carrier between the image and the visible side of the data carrier or in the visible side of the data carrier itself above the image, the image is first printed and then the coding takes place in the area in one or more layers above the image.

In a further variant, the image is printed and, independently of this, the coding takes place with the image-specific results of the image in a carrier layer film, which is then positioned and fixed above the image.

Within the scope of the invention, the image-specific results calculated from the digital image include all possible results determined from the respective portrait, such as the contours of a face, the position of individual, specific points of a face (landmarks) or other support structures analogous to the minutiae in a fingerprint , but also other image-specific results, thus all specific results that can be uniquely calculated from the digital image (in) by calculation using a specific algorithm.

The image contours can be calculated from the visible image or light image, for example, with Canny Edge Detection (Canny or Canny Edge algorithm). Canny-Edge (or Canny) -Detection is a robust algorithm for edge detection that is widely used in digital image processing. It is divided into various convolution operations and provides an image which ideally only contains the edges of the original image.

Using Canny Edge Detection, specific, i.e. unique, contours or support contours based on the algorithm can be extracted from a portrait and output as a separate contour image. Of course, other algorithms can also be used to extract a contour image from the visible image.

In a further variant of the invention, the image-specific results are calculated using landmarks detection. Here, the positions of individual, specific points on a face are calculated and the calculated landmarks image is then encoded in the printed image, for example by means of transparent luminescent ink.

In order to be able to check the correspondence of the visible image with the image-specific results coded in the image, the image-specific results must be detectable. In order to be able to detect, ie observe, recognize, measure or see these image-specific results coded in the image, the image-specific results can be printed in the visible image, in particular by means of a luminescent ink, or in the form of a hologram, barcode or milling or in other ways for example, visually or haptically perceptible or measurable form can be introduced into the layer area above the visible image.

The authenticity of an image printed on a data carrier can be checked visually in the case of a visible coding such as a hologram or milling. In addition, the image-specific results to be expected can be calculated from the visible image and their correspondence with the image-specific results encoded in the image or in the region of the layer above the image can then be checked.

If the expected image-specific results calculated on the basis of the printed image match the coded image-specific results, the image is genuine and the image was produced using the method according to the invention.

If no match is achieved, the printed visible image is a forgery because either no image-specific results are encoded in the printed visible image or because the image-specific results encoded in the image do not match the image, for example because the original image was overprinted.

For a reliable check of the authenticity of the image, if the check is carried out by calculating the expected image-specific results from the visible image, the calculation should be carried out using the same algorithm as the original calculation of the image-specific results from the data of the digital image.

The authenticity of the coded visible image is preferably checked in an automated manner.

In addition to the automated check or as an alternative to this, the checking of the coding can also be carried out visually, insofar as it is visible or can be made visible by exposure to electromagnetic radiation, such as UV radiation.

After the image-specific results, which were calculated from image-specific data of the photo, are stored in the image itself or have been introduced into an area of the layer above the image, it can be determined solely by checking the photo and possibly the layer area above the image whether the photo has been manipulated or not, because if the image-specific results stored in the photo do not match the photo, it is a forgery.

The authenticity of the document can thus be checked solely by checking the photo as such and, if applicable, the area located above, and preferably in an automated manner, which allows a reliable and quick check.

In a preferred embodiment, the image-specific results are the image contours or landmarks calculated from the image-specific data. However, other image-specific results can also be stored in the image.

The image-specific results, in particular image contours or landmarks, can be stored in the image in various ways, for example by printing the image contours or the landmarks in the image using luminescent transparent ink, so that the image contours or landmarks are only visible under UV light and thus The correspondence of the image contours or landmarks with the photograph can only be checked under UV light.

The image contours can, however, also be provided as a hologram or volume hologram, with a carrier layer film, such as a holographic film, exposed with the image-specific results, in particular the contours, and then applied, glued and sealed to the photograph with a precise fit.

In a further variant, the image-specific results, in particular image contours or landmarks, are removed from a layer area above the image, in particular on the visible side of the data carrier, for example by laser ablation. As a result, a data carrier card with a photograph is obtained in which the contours milled into the visible side as tactile depressions in a real document match the contour of the underlying photograph with an exact fit.

The data carrier comprises one or more layers made from the following plastics or their derivatives, namely from polycarbonate, bisphenol A polycarbonate, carboxy-modified PC, polyesters such as polyethylene terephthalate (PET), its derivatives such as glycol-modified PET (PETG), carboxy-modified PET , Polyethylene naphthalate (PEN), vinylic polymers such as polyvinyl chloride (PVC), polyvinyl butyral (PVB), polymethyl methacrylate (PMMA), polyvinyl alcohol (PVA), polystyrene (PS), polyvinyl phenol (PVP), polypropylene (PP), polyethylene (PE), polyacrylonitrile butadiene styrene , Polyamides, polyurethanes, polyureas, polyimides or thermoplastic elastomers (TPE), in particular thermoplastic polyurethane (TPU).

A particularly preferred variant with a luminescent ink is explained in detail below.

In this variant, in addition to the visible image, the image also has an invisible luminescent contour image which can be made visible under a UV source and thus the correspondence of the contour image with the visible image can be checked. The visible image is thus overprinted with its own invisible contour image.

The fact that a contour image is provided via a luminescent dye that is only visible through UV irradiation makes (light) image manipulation visible through film overlay or by overprinting under UV light, since the unambiguous contour calculated using the visually visible original light image and, in particular, its Support structures only match the original photograph. If the photo is manipulated in the visible, the contour would no longer match the manipulated photo and the forgery would be uncovered.

In the case of a mechanical or chemical shave, in which the luminescent contour image is also changed, there is no longer any correspondence at all, neither with the original light image nor with the manipulated image, so that the forgery is also recognizable. Of course, this also applies to mechanical or chemical shaving of holograms or milled contours.

Thus, in this variant, the light image can be encoded invisibly using characteristic spatial image elements and thus secured.

The contour or landmark image is preferably printed with the luminescent transparent ink together with the printing of the visible image with the colored inks. In a preferred variant, in addition to the color channels for the chromatic colors (CMYK), a further color channel (spot color) for the luminescent ink is provided in the printer so that all inks can be printed at the same time.

The result is an image that can be seen in daylight or when exposed to radiation with white visible light is a "normal" image of the document holder, but makes only the relevant contours or landmarks of the image visible as luminescent lines under UV excitation.

In addition, the contour or landmarks image can also first be printed with the luminescent transparent ink and only then can the visible image be printed in the contour or landmarks image or the visible image can be generated first and then the contour or image can be added to the visible image. Landmarks image can be printed.

In a further variant, the contour or landmarks image is printed with the luminescent transparent ink on a first carrier layer, for example based on polycarbonate, and the visible image with the colored inks on a second carrier layer, preferably also based on polycarbonate. The carrier layers are then positioned with respect to one another and then joined together, in particular laminated with an increase in temperature and pressure, as in FIG DE 10 2007 052 947 A1 described.

In principle, all inks can be used as luminescent transparent inks to which the desired dyes which absorb in the UV and which are luminescent and transparent in the visible and which are suitable for printing the respective data carrier have been added. The proportion of the luminescent dye is preferably up to 10% by weight.

For printing data carriers based on polycarbonate polymer layers, those from the DE 10 2007 052 947 A1 known inks are used. Such inks contain up to 20% by weight of a binder with a polycarbonate based on a geminally disubstituted dihydroxydiphenylcycloalkane, at least 30% by weight of an organic solvent, up to 10% by weight based on the dry weight of a colorant or colorant mixture and, if applicable, functional materials, Additives and / or auxiliaries. Preferred solvents are hydrocarbons and / or ketones and / or organic esters.

These inks can be printed on polycarbonate polymer layers with inkjet printers and then laminated to form a composite with impressive optical properties.

In the case of the luminescent transparent ink, the colorants or colorant mixtures are luminescent dyes. Luminescent dyes are understood to mean substances that fluoresce, phosphoresce or afterglow.

So that the contour image printed with the ink with the luminescent dye is not visible and therefore transparent when illuminated in the visible spectral range, the luminescent dye should not absorb or only absorb very slightly in the visible spectral range.

A pure substance or a mixture of luminescent dyes can be used as the luminescent dye. In principle, the luminescent dye can be an inorganic or an organic substance, organic luminescent dyes being preferred. The luminescent dye must be excitable with UV radiation and soluble in the respective solvent of the ink. The luminescent dye or dyes can emit in the visible spectral range in different colors such as yellow, red, green, but also in mixed colors or even almost white.

Through the specific selection, composition and, if necessary, concentration ratios of one or more luminescent dyes and their excitation and emission wavelengths, special luminescences can also be generated, which can be detected visually under a UV lamp, but also spectroscopically and can represent a further security feature. If several luminescent dyes are provided which differ in their excitation and emission wavelengths, different luminescent colors can also be generated with different excitation wavelengths in the UV.

The selection and, if necessary, combination of special luminescent dyes thus enables a further security feature, because counterfeiters would not only have to check the luminescence of the Completely suppress the original contour image and integrate the contour image applied with luminescent ink into the fake image, but also use the same luminescent dye (mixture).

During the verification, a digital recording of the printed color photo in the security document can be made in order to calculate the contours or landmarks to be expected for the printed image from the digital data of the printed image. The expected contours are then compared with the luminescence contour image or landmarks image of the printed image measured under UV radiation. If the contours match, the photograph is real.

In order to be able to compare the contours calculated from the recorded printed photo and thus to be expected in the photo with the originally calculated and invisibly printed contours in the colored image, the digital recording of the printed image in the security document should under the same conditions as the production of the original digital image , ie under white light, preferably with an RGB camera.

The prerequisite for the method according to the invention is therefore that both the calculation of the contour or landmarks image from the original digital image and the calculation of the contour or landmarks image from the recorded printed photo are carried out using the same algorithm and thus under UV Radiation recorded luminescence contour or landmarks image can be compared with the contour or landmarks image calculated from the printed image.

Since the UV light penetrates into the deeper layers of the security document during the irradiation, the luminescent dye can also absorb the UV radiation underneath the surface of the security document and also below a forged overprinted image and convert it into luminescent light. The contour image produced in the layer of the original image when UV radiation is absorbed by the luminescent dye is visible on the surface of the security document even if the original image is covered by a forged image a large part of the luminescent radiation passes through the layer of the forged image.

The method according to the invention can also be applied to other images on security documents or documents of value that are not photographs.

Security documents in the form of book-like documents, such as passports, for example, comprise, in addition to the laminated data carrier, a book cover and a book block which includes the data carrier.

• Figur 1 die Verfälschung des Bildes eines Dokumenteninhabers durch Überdruck,
• Figur 2 ein digitales Lichtbild, eine daraus berechnete Kontur und die Überlagerung der berechneten Kontur mit zwei verschiedenen Bildern,
• Figur 3 die Herstellung eines gedruckten Bildes mit überdrucktem Konturenbild,
• Figur 4 die Verifikation der Konturen,
• Figur 5 die Herstellung von Konturen in der Sichtseite eines Datenträgers mit einem Laser, und
• Figur 6 die Herstellung von Konturen in einem Datenträger mit Bild in Form eines (Volumen)-Hologramms

The invention and further advantageous embodiments and developments thereof are described and explained in more detail below with reference to the examples shown in the drawings. Show it:

• Figure 1 the falsification of the image of a document holder by overprinting,
• Figure 2 a digital photo, a contour calculated from it and the superimposition of the calculated contour with two different images,
• Figure 3 the production of a printed image with an overprinted contour image,
• Figure 4 the verification of the contours,
• Figure 5 the production of contours in the visible side of a data carrier with a laser, and
• Figure 6 the production of contours in a data carrier with an image in the form of a (volume) hologram

Figure 1 shows the photograph of a document holder "original", the photograph of another person "overprint" and the falsification of the original by overprinting the photograph of the other person. If the security features of the original remain intact after the falsification, the falsification cannot be recognized.

In Figure 2 a digital photo 10 ("image 1") and the contour image 13 of this photo 10 ("contour 1") calculated with the Canny Edge Detection is shown. When the contour image 13 (contour 1) is superimposed on the light image 10 (image 1), the contours match, the contour 1 "fits" to the image 1.

If, on the other hand, the contour image 13 “contour 1” is superimposed with the light image 10 '(image 2), which deviates from image 1, it can be seen, for example, in the chin and eyebrow area that the portrait in image 2 deviates from contour 1.

Since different people have different contours and the contours are image-specific, they can be used for verification.

The contour image 13 (contour 1) printed with the luminescent ink 24 is preferably only visible under UV radiation.

Figure 3 shows the expanded processing of the image data as part of the personalization of a security or value document 21. In addition to the processing of the digital image 10 in a raster imaging process (RIP) for the color printing of the image 15 with the colored inks 16, 17, 18, 19 the contours of the digital image 10 are extracted by means of the Canny Edge Detection. Here, specific contours or support structures are calculated from the portrait and output as a separate contour image ("Canny contour").

This contour image 13 is prepared as a separate color channel (spot color) during printing and simultaneously with the colored colors (cyan, magenta, yellow, core (CMYK)) with transparent luminescent ink 24, which is only visible under UV radiation ("spot"), printed.

The result is a printed image 15, 13 that is visible as a "normal" image 15 of the document owner in the printing inks YMYK, in which the contours are coded, since these are only visible as luminescent lines under UV excitation.

In order to prove the verifiability of the authenticity of a photograph based on the Canny contours, shows Figure 4 the original image 10 (above) and the forgery 10 '(below), from which the respective Canny contour images 13, 13' were calculated. The superposition of the Canny contour images 13, 13 'from the original 10 and the forgery 10' shows that they do not match.

During the verification, the visible light image 15 is recorded with an RGB camera under white light and from this with the Canny Edge method calculates the expected contours 12e. The verification should be done with the same procedure as the image data processing.

The document is then excited, for example with UV radiation, for example with a wavelength of 365 nm, and the luminescence image of the contour image 13 is recorded and compared with the image of the calculated expected contours 12e. Correspondences between the measured contour image 13 printed with the luminescent ink 24 and the contours 12e calculated from the RGB image verify the light image 15 or, if they do not correspond, indicate a manipulation.

Figure 5 shows on the left-hand side schematically the structure of a data carrier 20 of a security document 21, which consists of several layers 27 and a printed image 15, which are laminated to one another to form a composite. The printed image 15 is located within the layer composite. The area 25 of the layer 27, which extends above or above the image 15 in the direction of the visible side 28, is transparent and thus enables the view of the image 15. In this area 25 of the layer 27 located above the image 15, in the example of FIG Figure 5 In the visible side 28 in the area 25 of the layer 27, the contours 13 (support contours) or landmarks 14 are now precisely fitted into the finished data carrier 20 by means of laser ablation using a suitable laser 40, for example a CO ₂ laser (wavelength 10 micrometers) or a CO laser (wavelength 5 micrometers).

The result is a data carrier in which the contours 13, 14 are milled precisely above the printed image 15, the contours 13, 14 representing more or less tactile depressions.

In Figure 6 a holographic film 26, that is to say a carrier layer film 26, is shown on the left-hand side, in which the calculated contours are exposed by means of a laser 40 to produce a hologram 13. The holographic film 26 is then applied precisely to the data carrier 20 above the printed image 15, connected to the data carrier 20 by means of an adhesive layer 29, and the surface is then sealed with a scratch-resistant varnish 30.

The result is a data carrier with a photo 15 and precisely fitting holographic contours above the photo 15.

List of reference symbols

10

digital image

12th

image-specific results

12 '

Contours

12 "

Landmarks

12e

expected contours

13th

Contour image

14th

Landmarks image

15th

printed visible image

16

colored ink

17th

colored ink

18th

colored ink

19th

colored ink

20th

Disk

21

Security or value document

24

luminescent transparent ink

25th

Area of the data carrier above the image 15

26th

Movie

27

Layer of the data carrier

28

Visible side of the data carrier

29

Adhesive layer

30th

Scratch-resistant varnish

40

laser

Claims (15)

A method for verifying the authenticity of an image printed on a data carrier (20) visible image (15) encoded with detectable frame specific results (12), characterized in that calculated from the visible image (15) to be expected image specific results (12 ^s) and then their agreement with the image-specific results (12) encoded in the image (15) or in the area (25) of the layer (27) above the image (15) is checked. Method for checking the authenticity of a visible image (15) printed on a carrier (20) for a security or value document (21) which is encoded with detectable image-specific results (12), characterized in that a digital recording of the printed visible image ( 15) generated, from this expected image-specific results (12), in particular image contours (12 ') or landmarks (12 "), calculated and the expected image-specific results (12) with the coded image-specific results, in particular one measured under UV irradiation Luminescence contour image (13) or landmarks image (14) in the printed image (15, 14, 13) can be compared. Method according to Claim 2, characterized in that the digital recording of the printed image (13, 14, 15) in the security or value document (21) takes place under white light with an RGB camera. Method according to one of Claims 1 to 3, characterized in that the authenticity of the coded visible image (15) is checked in an automated manner. Method according to one of the preceding claims, characterized in that the calculation of the image-specific results (12 ^e ) to be expected from the visible image (15) using the same algorithm as the original calculation of the image-specific results (12) from the data of the digital image (10 ) he follows. Method according to one of Claims 1 to 5, characterized in that the visible image (15) is printed with colored inks (16, 17, 18, 19) based on the data of a digital image (10), from the data of the digital image ( 10) image-specific results (12) are calculated and the visible image (15) and / or an area (25) of at least one layer (27) of the data carrier (20) above the image (15) is encoded with these results (12) in a detectable form (13, 14). Method according to claim 6, characterized in that the coding of the image (15) takes place simultaneously with, before or after the printing of the visible image (15) and / or the coding of the area (25) of the layer (27) above the Image (15) has taken place after the image (15) has been printed or that the coding has taken place in a carrier layer film (26), which is then positioned and fixed above the image (15). Method according to one of the preceding claims, characterized in that the coding is visible or invisible in visible light. Method according to one of the preceding claims, characterized in that the image-specific results (12) from a face of the digital image (10) calculated contours (12 ') of the face, positions of individual specific points of the face (landmarks) (12 ") or others Support structures are analogous to minutiae in a fingerprint. Method according to claim 9, characterized in that the calculation of the contours (12 ') is carried out with the Canny-Edge-Detection, in particular in the form of support contours or specific contours. Method according to one of the preceding claims, characterized in that the detectable image-specific results (12) in the visible image (15) or an area (25) of the layer (27) above the image (15) by means of a luminescent transparent ink (24) are printed, or in the form of a hologram, barcode or milling or in another visually, haptically or otherwise perceptible or measurable form in an area (25) of the layer (27) above the image (15). The method according to claim 11, characterized in that the milling is carried out by laser ablation or that the hologram is introduced into the layer area (25) above the image (15) in that a holographic carrier layer film (26) with the image-specific results (12), in particular contours (12 '), exposed and this then on the printed photo (15) is positioned and possibly sealed. Method according to one of the preceding claims, characterized in that the data carrier (20) has one or more layers (25, 26) made of the following plastics or their derivatives, namely polycarbonate, bisphenol-A polycarbonate, carboxy-modified PC, polyesters such as polyethylene terephthalate (PET), glycol-modified PET (PETG), carboxy-modified PET, polyethylene naphthalate (PEN), vinylic polymers such as polyvinyl chloride (PVC), polyvinyl butyral (PVB), polymethyl methacrylate (PMMA), polyvinyl alcohol (PVA), polystyrene (PS), polyvinyl phenol ( PVP), polypropylene (PP), polyethylene (PE), polyacrylonitrile butadiene styrene, polyamides, polyurethanes, polyureas, polyimides or thermoplastic elastomers (TPE), in particular thermoplastic polyurethane (TPU). Method according to one of the preceding claims 2 to 13, characterized in that the printing is carried out by means of luminescent transparent ink and the luminescent transparent ink (24) up to 10% by weight of at least one soluble luminescent dye which can be excited by means of UV radiation and emits in the visible spectral range and / or that during printing the luminescent transparent ink (24) was supplied via an additional color channel or that the inks (16, 17, 18, 19, 24) have up to 20% by weight of binder with a polycarbonate based on a geminal disubstituted Dihydroxydiphenylcycloalkane comprise and at least 30% by weight of organic solvents, in particular hydrocarbons and / or ketones and / or organic esters. Method according to one of the preceding claims, characterized in that the detectable coding can be made visible in the visible spectral range or under electromagnetic radiation and the verification of the conformity of the visible image (15) with the detectable coding takes place visually in daylight or under electromagnetic radiation.

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