Method for Producing Security Elements in an Image Which are not Visible to the Human Eye and Cannot be Copied, and Printed Image

Abstract

A method for producing security elements in an image which are not visible to the human eye and which cannot be copied, in particular for checking the authenticity of images. The image is imaged by means of a halftone, the halftone consisting of individual image dots arranged adjacent to each other. This is characterized in that at least one field having a random geometric shape or freeform is defined in the image/the halftone. By means of manipulation of image dots in the field and/or by means of manipulation of the entire field, an encrypted information that cannot be copied is stored for comparison with at least one database and the serial number is displayed by means of contours formed in the halftone.

Claims

1. A method for producing security elements in an image which are not visible to the human eye and which cannot be copied, in particular for checking the authenticity of images, the image being imaged by means of a halftone, the halftone consisting of individual image dots arranged adjacent to each other, characterized in that at least one field having a random geometric shape or freeform is defined in the image/the halftone, wherein, by means of manipulation of image dots in the Field and/or by means of manipulation of the entire field, an encrypted information that cannot be copied is stored for comparison with at least one database and the serial number is displayed by means of contours formed in the halftone.

2. The method according to claim 1, characterized in that each contour is assigned at least one digit of the serial number.

3. The method according to claim 1, characterized in that the serial number can be represented in any number system.

4. The method according to claim 1, characterized in that the halftone is produced by duplex printing, four-color printing or multi-color printing or hexachrome printing, letterpress, gravure printing, planographic printing, through-printing, non-impact printing, 3D printing or a combination of at least two printing processes.

5. The method according to claim 1, characterized in that the serial number is represented at least in binary form, wherein a deviation of the halftone within the defined field is detected as 1=true and an identical halftone within the Field (F1 to F5) as 0=false or vice versa, depending on the previous definition.

6. The method according to claim 1, characterized in that information for decryption is stored in the serial number, wherein the encryption is carried out with the aid of a hash function assigned to the serial number, and in that the hash function used is integrated in the serial number as information.

7. The method according to claim 1, characterized in that the dots in the halftone have at least one, preferably four colors, wherein the manipulation of the dots and/or the fields is achieved by means of exchanging the halftone angle between two or more colors and/or changing the halftone angle of at least one color and/or changing the running width or halftone frequency of the cross-line halftone of at least one color and/or changing the frequency for frequency-modulated halftones of at least one color and/or changing the amplitude for amplitude-modulated halftones of at least one color and/or changing the frequency for amplitude-modulated halftones of at least one color and/or changing the amplitude for frequency-modulated halftones of at least one color.

8. The method according to claim 1, characterized in that the dots in the halftone have at least one, preferably four colors, wherein the manipulation of the dots and/or the fields is achieved by means of changing the surface area of dots of at least one color and/or changing the contour of the dots of at least one color.

9. The method according to claim 1, characterized in that the dots in the halftone have at least one, preferably four colors, wherein the manipulation of the dots and/or the fields is achieved by means of adding at least one color in form of infrared, ultraviolet or other special color or lacquer and/or exchanging at least one of the colors in the CMYK color space with another color in the form of infrared, ultraviolet or other special color or lacquer and/or replacing the color tones achieved by subtractive color mixing of the process colors with at least one special color or spot color and/or changing the achromatic structure by replacing equal parts of the process colors CMY completely or partially with black (K) and/or an additional black tone and/or changing the color composition when printing with more than four process colors.

10. The method according to claim 1, characterized in that the printing of the image is carried out by means of a printing process such as ink-jet, laser, offset, gravure, flexographic, screen printing or the like, and the printing is carried out on paper, plastics or other natural materials such as wood, stone or artificially produced printing substrates.

11. The method according to claim 1, characterized in that the serial number and a transformed code is stored in the form of a hash value in at least one database and assigned to a container with a serial number and supplemented by further product data, wherein the product data comprises at least the brand and/or name and/or place of production and/or production time and/or size and/or color and/or text length.

12. The method according to claim 1, characterized in that the container is filled with hash values, wherein the container itself is subsequently encrypted in such a way that the Merkle tree procedure is used, wherein two hash values of a serial number are always combined with a defined hash function to form a new transformed code and the resulting new hash value is stored in the database and thereupon two already combined hash values of serial numbers are encrypted again with a hash function (identical or modified), where this step is repeated until a hash value is available for the whole container, wherein the encryption path and the hash functions used are also stored in the database, which creates a Merkle path of the container.

13. The method according to claim 1, characterized in that the final hash value of the container is written to at least one blockchain.

14. The method according to claim 1, characterized in that the sequence for the coding is as follows: a) Rasterization of a graphic in RGB color space in a hardware or software raster image process (RIP) into a CMYK halftone or into another printable color space consisting of more or less colors b) Determination of the optical coding of the serial number, including: a. Determination of the areas for coding; b. Determination of the outer contours of the coding; c. Determination of the sequence in which the areas are arranged in sequence for coding; d. Determination of the hash function for the transformation of the serial number (1); c) Creation of the serial number (1.1) for the implementation into the graphic; d) Changing the rasterization according to the coding information of the serial number (1.1); e) Printing the information; and in that the sequence of scanning and decoding is as follows: i) Recording of the print image (CMYK or other printable color space); j) After recording, the data is available in the RGB color space or in another color space recognizable by optical systems such as camera systems; k) Application of filters and Fourier transformation; l) Recognition of fields/areas if there is information 0 or 1 (binary case) per code field and reading of the serial number (1.1), wherein in case of variation of the halftones for several colors or in case of using several variation possibilities per color or for each variation a value is assumed, for all CMYK then e.g. 0,1,2,3 and in case of using special colors further information states per special color; m) Comparison with DB1 in which fields the information for the optical decoding (field contour, sequence and hash function) for serial number (1.1) is located; n) Determination of the decoding value; o) Determination of the serial number (1) and transformation of the serial number (1) using the corresponding hash function; p) Further processing of the hash value of the serial number (2); and in that the database DB1 is at least one database, at least one cloud and/or at least one blockchain in which the relevant information is stored completely, split and/or encrypted or openly, wherein the information in DB1 can also represent links to further databases, clouds, blockchains from which information can be obtained via APIs or further interfaces.

15. A printed image (A) having at least one security element that cannot be copied, wherein the image (A) is printed from a halftone image with individual dots, characterized in that the image (A) has, within its halftone image, information which can be evaluated in such a way that the image (A) has at least one field (F1 to F5) which has a manipulation of the dots of the halftone image which is not visible to the human eye, and wherein a serial number is displayed by means of contours introduced into the halftone image.

16. The printed image (A) according to claim 15, characterized in that at least one digit of the serial number is assigned to each contour introduced into the halftone image.

17. The printed image (A) according to claim 15, characterized in that the serial number can be represented in any number system.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0125] The invention is explained in more detail in the following by reference to an exemplary embodiment and associated drawings, wherein:

[0126] FIG. 1 shows a schematic representation of an image,

[0127] FIG. 2 shows a rotated halftone angle in the color black,

[0128] FIG. 3 shows a rotated halftone angle in the color magenta.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0129] FIG. 1 shows a schematic image A with a dot grid 1. To improve the display, lines arranged in parallel as halftone image have been used in the illustration for better representation. However, the halftone image consists of dots which are arranged next to each other.

[0130] The image shows 5 fields F1 to F5, wherein each field F1 to F5 has any geometrical shape or free form.

[0131] By means of the fields F1 to F5, information can be displayed in image A. The human eye cannot recognize differences and does not perceive any fields in image A.

[0132] The fields F1, F3, F4 and F5 show a different orientation of the halftone image compared to image A. Field F2 has the same orientation of the halftone image as the halftone image of image A.

[0133] From the orientation of the dots a binary representation can be generated in such a way that in case of a deviating orientation of the dots of the field F compared to the image A, a 1 or a 0 can be generated, depending on the previous definition. In case a deviation generates a 1, this means that the field F2 generates a 0 and the fields F1, F3, F4 and F5 generate a 1, whereby a serial number can be represented binary. Beside the value 1, the fields F3 and F4 can assume the values 2 and 3 respectively, due to the further modification.

[0134] A preferred case is the use of 4 colors CMYK and display of the serial number in the halftones for the colors black (K) according to FIG. 2 and magenta (M) according to FIG. 3, with the halftone angles swapped between K and M in selected areas.