A method and system for reducing the appearance of a security feature viewed under UV (Ultra Violet) illumination can include selecting a colorant, wherein the colorant comprises a first UV spectral reflectance property, selecting a matching colored media, which matches a color of the colorant and which comprises a second UV spectral reflectance property that is different from the first UV spectral reflectance property, and adjusting the color of the colorant and a color of the matching color media to match one another and produce an adjusted colorant that facilitates a reduction in a visibility of the security feature based on the adjusted colorant.

There is provided a luminescent medium which requires difficult analysis of light emitted from a luminescent material of the medium. A luminescent medium includes a substrate, and a luminescent material comprising a first luminescent material which, when irradiated with visible light, infrared light or ultraviolet light, emits first infrared light “a”, and a second luminescent material which, when irradiated with visible light, infrared light or ultraviolet light, emits second infrared light “b”. The first luminescent material is formed in a first planar area, and the second luminescent material is formed in a second planar area. The first planar area and the second planar area overlap each other, forming an overlapping planar area in which the luminescent materials each have a concentration gradation.

The objective of the present invention is to provide an information recording body, a medium and a printed product having improved design properties. An information recording body provided with a superimposed image including a brilliant layer and a transparent layer formed on the brilliant layer is characterized in that: the brilliant layer is a chromatic color image formed from a brilliant material; the transparent layer is a regular pattern image formed from a transparent starting material; the transparent starting material is configured in such a way that an amount of light reflected therefrom differs depending on an observation angle; and the superimposed image is formed in such a way that the transparent layer is recognizable in accordance with a specific observation angle.

Security of a printed matter is enhanced, and a visual image is made clear if a latent image formed by a coating printed on a matter to be printed for a security enhancement of the printed matter becomes the visual image. A security ink pigment contains a powder. A main constituent of the powder is a perovskite-type oxide. The perovskite-type oxide has a composition expressed as a general formula of ABO.sub.3. A is mainly made of Ba. B is mainly made of Sn. The powder emits an infrared fluorescence when being irradiated with an ultraviolet excitation light. The perovskite-type oxide has a crystal lattice constant having a difference equal to or smaller than 0.002 angstrom from a theoretical crystal lattice constant of the perovskite-type oxide having a composition expressed as a composition formula of BaSnO.sub.3.

A printing system receives a print request containing patterns of marks to be printed on print media to produce printed output. A processor evaluates the print request to identify non-marking areas and identify different printing densities of the patterns of marks. The processor alters the patterns of marks to create hidden features on the printed output by adding a uniform printed background to the non-marking areas and adding different printing densities of fluorescent spots to different areas of the patterns of marks. The different printing densities of the fluorescent spots are based on the different printing densities of the patterns of marks and on the size of the hidden features. A printing device prints the print request on the print media to produce the printed output.

A method of printing a stealth white image includes applying a stealth ink containing a red coloring material that emits visible light at exposure to ultraviolet radiation and a green coloring material that emits visible light at exposure to ultraviolet radiation to a substrate which contains a fluorescent brightener to form the stealth white image thereon, wherein the stealth white image demonstrates an a* value of from −2.0 to 2.0 and a b* value of from −10.0 to 0 at exposure to ultraviolet radiation having a wavelength of 370 nm according to CIE 1976 L*a*b* colorimetric system.

The present invention relates to the field of security inks suitable for printing machine readable security features on substrate, security documents or articles as well as machine readable security feature made from said security inks, and security documents comprising a machine readable security feature made from said security inks. In particular, the invention provides security inks comprising one or more IR absorbing materials selected from the group consisting of crystal water-free iron(II) orthophosphates of the general formula Fe.sub.3(PO.sub.4).sub.2 and having a graftonite crystal structure, crystal water-free iron(II) metal orthophosphates, crystal water-free iron(II) metal phosphonates, crystal water-free iron(II) metal pyrophosphates, crystal water-free iron(II) metal metaphosphates of the general formula Fe.sub.aMet.sub.b(PO.sub.c).sub.d, wherein said security ink is an oxidative drying security ink, a UV-Vis curable security ink, a UV-Vis curable security ink or a combination thereof.

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.

A printed article includes: a base layer and a surface layer, at least one anti-counterfeit label disposed between the base layer and the surface layer. The surface layer and the anti-counterfeit label are formed via ink printing. The printed article is equipped with the anti-counterfeiting function, and the anti-counterfeit label provided can be used for authenticity identification. The anti-counterfeit label is concealed inside the printed article such that it cannot be detected easily. When a light is shone onto the printed article, the anti-counterfeit label shows on the printed article.

To provide a light-emitting medium whereby different light-emitting forms can be realized that can easily be discriminated using a normal blacklight, and to provide a forgery prevention medium and a method for determining authenticity of the light-emitting medium. A light-emitting medium provided with a substrate and a first light-emitting region and a second light-emitting region disposed on both sides of the substrate, the substrate comprising a selective transmission region for transmitting non-visible light in a first wavelength region and essentially not transmitting non-visible light in a second wavelength region different from the first wavelength region, and the first light-emitting region and the second light-emitting region emitting light when irradiated by non-visible light in the first wavelength region and also emitting light when irradiated by non-visible light in the second wavelength region.