Method for reading a code stored in a halftone image and comparison with a retrievable value

A method for checking the authenticity of products, by checking an image (A) of a product, wherein the proof of authenticity is not visible to the human eye and cannot be copied, characterized in that a code stored in a halftone image by manipulation of dots and/or a manipulated field bounded in the halftone image can be read by means of an optical device and compared with a retrievable value in at least one database, wherein in at least one field (F1 to F5) a part of a serial number is determined which describes the structure of the serial number and a hash function used for transmitting the serial number to the database, and in that the serial number is subsequently assembled and encrypted with the corresponding hash function, wherein the encrypted serial number is sent to the database and a Merkle path stored for this hash value is determined, wherein an associated container hash is determined via the Merle tree method, and wherein

• the sequence for coding is as follows:
• a) rasterization of a graphic in RGB color space (or another 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. Definition of the areas for coding;
• b. Definition 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) change 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 colors ace 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 severel 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 APls or further interfaces.