Method of printing authentication indicators with amplitude modulated halftone printing
AssigneeU-Nica Systems AG
InventorKlaus Franken
Life of this patent
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Abstract
A method of printing authentication indicia by applying an at least amplitude-modulated halftone print in a detection zone to an object uses adjoining halftone cells, in each of which a halftone dot is printed from a matrix of printable halftone elements, individual tone values of the halftone print corresponding in each case to a halftone plane of a halftone mountain for a halftone dot. In this process, the assigned screen plane of the screen mountain is modified in the detection zone in a predetermined manner for a plurality of tone values of screen dots to be printed, so that a predetermined matrix image of the screen elements to be printed is assigned to it while the tone value of the print remains constant.
Claims15
A method of printing authentication indicators by applying an at least amplitude-modulated halftone print in a detection zone to an object, comprising:
- providing a halftone mountain having a plurality of halftone planes with a predetermined halftone dot assignment for each plane, wherein individual tone values of the at least amplitude-modulated halftone print are associated to the plurality of halftone planes for a halftone dot to be printed, wherein the predetermined halftone dot assignment is changing between subsequent halftone planes of the plurality of halftone planes for different tone values creating asymmetrically modified matrix images over said subsequent halftone planes,
- providing adjoining halftone cells in the detection zone, wherein each of the adjoining halftone cells comprises a plurality of printable halftone elements, and
- printing the halftone dot in each of the adjoining halftone cells from the asymmetrically modified matrix images of the plurality of printable halftone elements.
An authenticating method of a printed object, wherein an at least amplitude-modulated halftone print in a detection zone is printed on the printed object, comprising:
- providing a portable image capture device having a microprocessor for executing an authentication program and having access to print data relating to the printed object;
- storing in print data:
- data relating to a halftone mountain having a plurality of halftone planes, with a predetermined halftone dot assignment for each plane, wherein individual tone values of the at least amplitude-modulated halftone print are associated to the plurality of halftone planes for a halftone dot to be printed, wherein the predetermined halftone dot assignment is changing between subsequent halftone planes for different tone values creating asymmetrically modified matrix images over said subsequent halftone planes,
- data relating to adjoining halftone cells in the detection zone, wherein each halftone cell comprises a plurality of printable halftone elements, and
- data relating to printed halftone dots in the adjoining halftone cells from the asymmetrically modified matrix images of the plurality of printable halftone elements,
- taking an image of the detection zone of the printed object;
- selecting a predetermined number of halftone dots in said detection zone from the image of the printed object;
- determining a print image of the detection zone predetermined from halftone mountain data for a predetermined number of halftone dots of the printed object from said detection zone for one or more individual tone values;
- providing a first computer program for identifying captured halftone dots from the image of the detection zone of the printed object;
- providing a second computer program for comparing the captured halftone dots with the print image predetermined from the halftone mountain data for the plurality of individual tone values;
- comparing the print image of the predetermined number of halftone dots with the print images predetermined from the halftone mountain data for the plurality of individual tone values;
- and
- deciding on the basis of the comparison whether or not there is an original print on the printed object.
Dependencies are inferred from the claim text.