A visual security feature is provided that is disposed on a target. The visual security feature includes two substantially transparent layers. At least one of the two substantially transparent layers is present in an image-wise pattern.

A 3D physical unclonable functions (PUF) system produced based on harnessing the out-of-plane crumpling of a layer of 2D material during shrinkage of a substrate carrying such layer. The structural details of the so-formed 3D PUF pattern are extracted from the tags in a layer-by-layer fashion using confocal laser microscopy imaging and then reconstructed to form the 3D PUF keys and stored in the database, serving as a secure anti-counterfeiting PUF that demonstrates encoding capacity in excess of 10.sup.40,000,000. Authentication is performed with a customized trained Siamese neural network framework in a matter of few minutes in a fashion that does not depend on rotation, linear translation, tilt, variations of contrast and/or resolution of the extracted optical images.

A device comprising: an optical emitter for emitting light having an emitted optical spectrum; an optical sensor for receiving light reflected from a tag attached to an object; and a processor configured to: determine a reflected optical colour spectrum of the light reflected from the tag based on an output of the optical sensor; retrieve an optical signature associated with said object from memory; and determine the authenticity of said object based on comparing the optical signature and the reflected optical colour spectrum.

A visual security feature is provided that is disposed on a target. The visual security feature includes two substantially transparent layers. At least one of the two substantially transparent layers is present in an image-wise pattern.

A visual security feature is provided that is disposed on a target. The visual security feature includes two substantially transparent layers. At least one of the two substantially transparent layers is present in an image-wise pattern.

A method of manufacturing a document of a series identical documents in content except for a respective identifier which identifies each document within the series, each identifier having at least a first indicium, the or each indicium defining a boundary; the method having the steps of: providing a substrate; applying a first background print, defining part of the boundary of an indicium receiving area; applying the respective identifier on the substrate, such that the first indicium is provided in the indicium receiving area; the first background print and the respective identifier being applied such that when the document is viewed in at least one of transmission and reflection the juxtaposition of the first background print and the first indicium is such that a keyline extending around a portion of the boundary of the first indicium is defined between the first indicium and the boundary of the indicium receiving area.

A method of manufacturing a document of a series identical documents in content except for a respective identifier which identifies each document within the series, each identifier having at least a first indicium, the or each indicium defining a boundary; the method having the steps of: providing a substrate; applying a first background print, defining part of the boundary of an indicium receiving area; applying the respective identifier on the substrate, such that the first indicium is provided in the indicium receiving area; the first background print and the respective identifier being applied such that when the document is viewed in at least one of transmission and reflection the juxtaposition of the first background print and the first indicium is such that a keyline extending around a portion of the boundary of the first indicium is defined between the first indicium and the boundary of the indicium receiving area.

A system for verifying the authenticity of a printed mark includes an image acquisition device that acquires an image of a printed mark. In one implementation, the printed mark includes an identifier that identifies the group or class of an item to which the printed mark is to be (or has been) attached. The system may also include one or more processors that carry out actions such as receiving the image from the image acquisition device; analyzing the image to identify artifacts in the printed mark, retrieving a genuine mark signature from a data storage containing genuine mark signatures, comparing the identified artifacts with the genuine mark signature, and determining whether the unverified item is authentic based on the comparison.

A thermal transfer print ribbon having radiation curable ink thereon is used to print on a surface of a plastic card. The use of radiation curable thermal transfer printing to print on the card surface increases the durability of the printing compared to regular (i.e. non-radiation cured) thermal transfer printing once the radiation curable ink is cured. As a result, a protective laminate or coating need not be applied to the card surface to protect the printing.

A thermal transfer print ribbon having radiation curable ink thereon is used to print on a surface of a plastic card. The use of radiation curable thermal transfer printing to print on the card surface increases the durability of the printing compared to regular (i.e. non-radiation cured) thermal transfer printing once the radiation curable ink is cured. As a result, a protective laminate or coating need not be applied to the card surface to protect the printing.