A method of inserting guilloche patterns in a document, each guilloche pattern being capable of encoding variable alphanumeric data ensuring a different aspect at each guilloche pattern so as to render said document secure using an operation of determining an insertion intensity of each guilloche pattern previously generated on the basis of a mid-gray level of the document near said guilloche pattern. A device for implementing this insertion method. The method further provides for extracting guilloche patterns from a secure document likely to be degraded by determining a contrast card of at least one portion of the secure document that includes the guilloche patterns, identifying, on this contrast card an optimal percolation trajectory, and extracting the optimal percolation trajectory, said trajectory corresponding to the guilloche pattern. The method further provides for authentication of the guilloche patterns of a secure document likely to be degraded, by the extraction operations, and comparing each extracted guilloche pattern with a corresponding theoretical guilloche pattern.

Disclosed is an anti-counterfeiting printed material including: a background part for analyzing a distribution of Cyan Magenta Yellow Black (C/M/Y/K) after performing first color separation of an original image into C/M/Y/K, and printing the original image as C/M/Y/K lines each having an included angle preset according to each distribution; and a latent image part formed in a first region of the background part, and printed with the number of C/M/Y/K lines in a ratio different from the number of C/M/Y/K lines of the background part according to each distribution by performing secondary color separation, into C/M/Y/K, of a second region spaced apart from the first region by a preset distance.

A security element with one or more first microstructures, wherein the first microstructures are provided in each case in one or more tracks which are curved at least in sections or in one or more sections of a track which are curved at least in sections, and/or in each case run along one or more tracks which are curved at least in sections or along one or more sections of a track which are curved at least in sections, and a method, wherein at least one file containing image points of one or more image elements is provided, which includes the locational arrangement of the image points, and one or more tracks which are curved at least in sections or one or more sections of one or more tracks which are curved at least in sections are determined from the locational arrangement of the image points, and in the one or more tracks or sections of tracks in each case one or more first microstructures are provided which, when illuminated, provide a first item of optically variable information.

A security element with one or more first microstructures, wherein the first microstructures are provided in each case in one or more tracks which are curved at least in sections or in one or more sections of a track which are curved at least in sections, and/or in each case run along one or more tracks which are curved at least in sections or along one or more sections of a track which are curved at least in sections, and a method, wherein at least one file containing image points of one or more image elements is provided, which includes the locational arrangement of the image points, and one or more tracks which are curved at least in sections or one or more sections of one or more tracks which are curved at least in sections are determined from the locational arrangement of the image points, and in the one or more tracks or sections of tracks in each case one or more first microstructures are provided which, when illuminated, provide a first item of optically variable information.

An anti-counterfeiting pattern having an optically variable structure, comprising lithographic lines and gravure blind embossed relief lines printed on a carrier. The lithographic lines are a set of lithographic curve lines having a curvature, the widths of the lithographic curve lines changing from thick to thin, or thin to thick. The gravure blind embossed relief lines are a set of curve lines corresponding to the lithographic lines, and having the same curvature. The relief lines are overprinted on the lithographic lines with a width variation identical to that of said lithographic lines. Accurate overprinting of the two printing types forms a curved relief structure wherein the width of the lines changes continuously. When a printed product is rotated and observed, a continuously variable optical effect will be seen, which is visual, readily to identify, anti-copying and difficult to forgery.

An anti-counterfeiting pattern having an optically variable structure, comprising lithographic lines and gravure blind embossed relief lines printed on a carrier. The lithographic lines are a set of lithographic curve lines having a curvature, the widths of the lithographic curve lines changing from thick to thin, or thin to thick. The gravure blind embossed relief lines are a set of curve lines corresponding to the lithographic lines, and having the same curvature. The relief lines are overprinted on the lithographic lines with a width variation identical to that of said lithographic lines. Accurate overprinting of the two printing types forms a curved relief structure wherein the width of the lines changes continuously. When a printed product is rotated and observed, a continuously variable optical effect will be seen, which is visual, readily to identify, anti-copying and difficult to forgery.

A method for authenticating an article including engraving a circular feature into a verification substrate that includes a plurality of concentric rings within the circular feature arranged in a pattern according to a data encoding schema, wherein at least one of the plurality of rings includes a surface anomaly. The method can include capturing a first image of the circular feature and storing the first image in a memory device. The verification substrate can be attached to an article to traced and/or authenticated. A second image of the circular feature can be captured and compared with the first image to determine if the surface anomaly is present in the second image, thereby authenticating the article.

A method for authenticating an article including engraving a circular feature into a verification substrate that includes a plurality of concentric rings within the circular feature arranged in a pattern according to a data encoding schema, wherein at least one of the plurality of rings includes a surface anomaly. The method can include capturing a first image of the circular feature and storing the first image in a memory device. The verification substrate can be attached to an article to traced and/or authenticated. A second image of the circular feature can be captured and compared with the first image to determine if the surface anomaly is present in the second image, thereby authenticating the article.

There is described a printed security element (10; 10*; 10**) comprising a rainbow feature (15; 15*; 15**) exhibiting, at least in part, a gradual transition from a first colour (C1) to a second colour (C2) distinct from the first colour (C1), wherein the rainbow feature (15; 15*; 15**) extends over a colour-gradient area (A) of the printed security element (10; 10*; 10**) where first and second printed patterns (P1, P2) are partly superimposed or juxtaposed, each of the first and second printed patterns (P1, P2) comprising a first, respectively second set of linear or curvilinear elements (20, 30; 20*, 30*), the first and second printed patterns (P1, P2) being printed in register one with the other by means of two distinct printing plates (PP1, PP2) so that the first and second sets of linear or curvilinear elements (20, 30; 20*, 30*) are partly superimposed or juxtaposed in the colour-gradient area (A) and thereby generate the rainbow feature (15; 15*; 15**), the first printed pattern (P1) exhibiting the first colour (C1) and being printed by means of a first printing plate (PP1) and the second printed pattern (P2) exhibiting the second colour (C2) and being printed by means of a second printing plate (PP2), where at least the first or second printed pattern (P1; P2) exhibits, in the colour-gradient area (A), a modulation of line width or line structure such as to cause, when superimposed or juxtaposed with the other printed pattern (P2; P1), a gradual transition from the first colour (C1) to the second colour (C2), wherein, in the colour-gradient area (A), the second printed pattern (P2) is printed on top of the first printed pattern (P1) and wherein the second colour (C2) is darker than the first colour (C1). Also described is a method of producing the aforementioned printed security element.

There is described a printed security element (10; 10*; 10**) comprising a rainbow feature (15; 15*; 15**) exhibiting, at least in part, a gradual transition from a first colour (C1) to a second colour (C2) distinct from the first colour (C1), wherein the rainbow feature (15; 15*; 15**) extends over a colour-gradient area (A) of the printed security element (10; 10*; 10**) where first and second printed patterns (P1, P2) are partly superimposed or juxtaposed, each of the first and second printed patterns (P1, P2) comprising a first, respectively second set of linear or curvilinear elements (20, 30; 20*, 30*), the first and second printed patterns (P1, P2) being printed in register one with the other by means of two distinct printing plates (PP1, PP2) so that the first and second sets of linear or curvilinear elements (20, 30; 20*, 30*) are partly superimposed or juxtaposed in the colour-gradient area (A) and thereby generate the rainbow feature (15; 15*; 15**), the first printed pattern (P1) exhibiting the first colour (C1) and being printed by means of a first printing plate (PP1) and the second printed pattern (P2) exhibiting the second colour (C2) and being printed by means of a second printing plate (PP2), where at least the first or second printed pattern (P1; P2) exhibits, in the colour-gradient area (A), a modulation of line width or line structure such as to cause, when superimposed or juxtaposed with the other printed pattern (P2; P1), a gradual transition from the first colour (C1) to the second colour (C2), wherein, in the colour-gradient area (A), the second printed pattern (P2) is printed on top of the first printed pattern (P1) and wherein the second colour (C2) is darker than the first colour (C1). Also described is a method of producing the aforementioned printed security element.