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.

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.

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.

Generation of one dimensional guilloche patterns able to be affixed on a document, each guilloche pattern being able to encode variable alphanumeric data providing a different appearance to each guilloche pattern, by formatting alphanumeric data to be encoded in the form of a predefined number of data blocks with a predefined size, generating a carrier function having a plurality of parameters, the formatted data blocks forming at least one of the parameters, and modulating the carrier function by the formatted data blocks so as to encode the alphanumeric data graphically, each data block defining a guilloche pattern, the number of data blocks defining the number of guilloche patterns, the carrier function associated with a formatted data block is modulated locally, each datum of the block being encoded locally in the guilloche pattern, by interpolation of a predefined point associated with the carrier function.

Generation of one dimensional guilloche patterns able to be affixed on a document, each guilloche pattern being able to encode variable alphanumeric data providing a different appearance to each guilloche pattern, by formatting alphanumeric data to be encoded in the form of a predefined number of data blocks with a predefined size, generating a carrier function having a plurality of parameters, the formatted data blocks forming at least one of the parameters, and modulating the carrier function by the formatted data blocks so as to encode the alphanumeric data graphically, each data block defining a guilloche pattern, the number of data blocks defining the number of guilloche patterns, the carrier function associated with a formatted data block is modulated locally, each datum of the block being encoded locally in the guilloche pattern, by interpolation of a predefined point associated with the carrier function.

A method for manufacturing a security document including a security pattern generation method includes the steps of selecting a bounding region, an image object, and a raster image or a function; cutting the image object into image object partitions; and repeating the image object as a pattern, preferably a lattice pattern, in the bounding region wherein each of the image object partitions of an image object is transformed depending on the position area of the image object in the lattice pattern and the rank of the image object partition.

A method for manufacturing a security document including a security pattern generation method includes the steps of selecting a bounding region, an image object, and a raster image or a function; cutting the image object into image object partitions; and repeating the image object as a pattern, preferably a lattice pattern, in the bounding region wherein each of the image object partitions of an image object is transformed depending on the position area of the image object in the lattice pattern and the rank of the image object partition.

A security document includes a first ink layer and a second ink layer. The first ink layer includes a first color in a first color zone and a second color in a second color zone offset from the first color zone in a first direction, and a first blended color including a mixture of the first and second colors in a first blended color zone between the first color zone and the second color zone. The second ink layer includes a third color in a third color zone and a fourth color in a fourth color zone offset from the third color zone in a second direction, and a second blended color including a mixture of the third and fourth colors in a second blended color zone between the third color zone and the fourth color zone. The first direction is different than the second direction.

A security document includes a first ink layer and a second ink layer. The first ink layer includes a first color in a first color zone and a second color in a second color zone offset from the first color zone in a first direction, and a first blended color including a mixture of the first and second colors in a first blended color zone between the first color zone and the second color zone. The second ink layer includes a third color in a third color zone and a fourth color in a fourth color zone offset from the third color zone in a second direction, and a second blended color including a mixture of the third and fourth colors in a second blended color zone between the third color zone and the fourth color zone. The first direction is different than the second direction.