The invention relates to a process for securing an identification document and to a secure identification document. More particularly, the process uses UV sensitive ink(s) to define a pattern only visible under UV radiations, by printing a first layer of a transparent ablation varnish (13), printing a layer (14) of UV sensitive ink(s) over said first layer of transparent ablation varnish, removing parts of the layer (14) of UV sensitive ink(s), by means of a laser beam, some remaining areas of said UV sensitive ink(s) defining said pattern to be revealed in color under UV radiations, and some areas, where the UV sensitive ink(s) has been removed and the laser beam has interacted with the ablation varnish (13), absorbing the UV radiations with effect of creating black color. Other systems and methods are disclosed.

A security sheet including an iridescent security mark observable on the surface of the sheet, the mark having at least one zone presenting an iridescent effect, the zone being colored in normal observation with the naked eye and including iridescent pigments that are practically colorless in normal observation and that present an iridescent effect visible only in oblique observation.

The absorbance or emission wavelength of composite materials comprising a transition metal doped shell disposed over a rare earth doped core and a functionalizable group on the surface of the transition metal doped shell can change upon subjection to a carboxylic acid. This method of changing the absorbance or emission wavelength of a composite material can be used to identify counterfeit currency using an ink comprising a composite material.

A method for producing a luminescent printing ink of a desired target spectral locus in which: Z) the desired target spectral locus is specified using standard chromaticity coordinates x, y; L) at least two luminescent pigments are specified by their luminescence spectra; B) from the luminescent spectra of the luminescent pigments, from spectral value functions, and from the specified target spectral locus, proportions by weight of the at least two luminescent pigments are determined, and M) the at least two luminescent pigments are mixed in the proportions by weight deter-mined in step B) in order to obtain a luminescent printing ink having a luminescence of which the spectral locus under illumination with non-visible excitation light corresponds substantially to the target spectral locus.

A multispectral watermark and method for generating the multispectral watermark. A color pattern can be provided, which appears a single color/pattern under a first lighting condition. A watermark can be created based on the color pattern and under a second lighting condition comprising ultraviolet light, while the watermark is viewable with an infrared camera in an infrared spectrum. The watermark can be configured as a multispectral watermark with a metameric pair of inks with one ink of the metameric pair of inks using more CMYK toners that reflect in the infrared spectrum as compared to the other ink among the metameric pair of inks while simultaneously allowing more of the ultraviolet light or less of the ultraviolet light to reach a fluorescing media upon which the multispectral watermark is rendered.

A method of producing a transparent polychromatic printed iridescent image (8) of any kind in which at least two colors change simultaneously when there is a change in the viewing angle of the image under illumination by at least one visible light source.

An upconverting pigment dispersion includes an upconverting pigment, such as a -NaYF.sub.4 crystal doped with at least one of Erbium, Ytterbium or Thulium. The upconverting pigment dispersion is aqueous. Upconverting inkjet ink is made by mixing the crystals with a polymer dispersant and water and milling the mixture until the crystal particles are between 50 nanometers and 200 nanometers. Deionized water, a colorant and a humectant are added to the milled mixture.

A credential with one or more security features is disclosed. The disclosed credential includes a windowed security feature. The windowed security feature is taught to include a mirror element positioned in proximity with a transparent window and a first photo-luminescent feature positioned relative to the transparent window and the mirror element such that the mirror element enhances a luminescence of the first photo-luminescent feature when viewed and illuminated through the transparent window.

The present invention relates to methods and apparatus for printing a security card. A security image is printed onto the receiving layer of a dye receptive reverse transfer film, which can then be applied to the card and bonded with the card. The printing of the security image occurs by transferring overcoat material from an overcoat panel of the dye carrying film onto the receiving layer of the dye receptive reverse transfer film in a pattern, which forms the visual security image. This process can be used in conjunction with the printing of a primary image by printing Yellow, Magenta, Cyan dyes and Black resin (YMCK) to the receiving layer in a reverse transfer printing method to provide a security card having a primary image and a security image. The security image printing may occur before or after the YMCK printing.

Techniques for manufacturing a light field print using a printing press. The techniques include: identifying at least one characteristic of the printing press at least in part by printing at least one calibration pattern; obtaining content to be rendered using the light field print, the content comprising multiple scene views; generating, based at least in part on the content and the at least one characteristic of the printing press, a front target pattern and a back target pattern; and using the printing press to: print the front target pattern on a first side of a substrate; and print the back target pattern on a second side of the substrate.