The invention relates to the field of the protection of security documents such as for example banknotes and identity documents against counterfeit and illegal reproduction. In particular, the invention relates to optical effect layers (OEL) showing a viewing-angle dependent optical effect, devices and processes for producing said OEL and items carrying said OEL, as well as uses of said optical effect layers as an anti-counterfeit means on documents. The OEL comprises a plurality of non-spherical magnetic or magnetizable particles, which are dispersed in a coating composition comprising a binder material, the OEL comprising two or more loop-shaped areas, being nested around a common central area that is surrounded by the innermost loop-shaped area, wherein, in each of the loop-shaped areas, at least a part of the plurality of non-spherical magnetic or magnetizable particles are oriented such that, in a cross-section perpendicular to the OEL layer and extending from the center of the central area to the outer boundary of the outermost loop-shaped area, the longest axis of the particles in each of the cross-sectional areas of the looped-shaped areas follow a tangent of either a negatively curved or a positively curved part of hypothetical ellipses or circles.

A micro-optic security device with zonal color transitions includes a planar array of focusing elements, an image icon layer including a plurality of retaining structures, the plurality of retaining structures defining isolated volumes at a first depth within the image icon layer, a first zone of image icons, the first zone of image icons having a first predefined subset of the plurality of retaining structures, wherein the isolated volumes of retaining structures of the first predefined subset of the plurality of retaining structures contain cured pigmented material of a first color, and a second zone of image icons, the second zone of image icons including a second predefined subset of the plurality of retaining structures, wherein the isolated volumes of retaining structures of the second predefined subset of the plurality of retaining structures contain cured pigmented material of a second color, wherein the second color contrasts with the first color.

A micro-optic security device with zonal color transitions includes a planar array of focusing elements, an image icon layer including a plurality of retaining structures, the plurality of retaining structures defining isolated volumes at a first depth within the image icon layer, a first zone of image icons, the first zone of image icons having a first predefined subset of the plurality of retaining structures, wherein the isolated volumes of retaining structures of the first predefined subset of the plurality of retaining structures contain cured pigmented material of a first color, and a second zone of image icons, the second zone of image icons including a second predefined subset of the plurality of retaining structures, wherein the isolated volumes of retaining structures of the second predefined subset of the plurality of retaining structures contain cured pigmented material of a second color, wherein the second color contrasts with the first color.

Methods and systems for optical effects in pigments, inks, and on media. One aspect of this disclosure involves a pigment particle which includes a core, having a fluorescent material and having a spherical shape, and a shell surrounding the core; the shell includes a photochromic material which has a first optical property in a first light source and a second optical property in a second light source which includes a set of wavelengths not sufficiently present in the first light source. The second optical property attenuates an emitted radiation from the fluorescent material. Other aspects are also described.

Methods and systems for optical effects in pigments, inks, and on media. One aspect of this disclosure involves a pigment particle which includes a core, having a fluorescent material and having a spherical shape, and a shell surrounding the core; the shell includes a photochromic material which has a first optical property in a first light source and a second optical property in a second light source which includes a set of wavelengths not sufficiently present in the first light source. The second optical property attenuates an emitted radiation from the fluorescent material. Other aspects are also described.

In the field of protection of value documents and value commercial goods, the present disclosure relates to the field of security threads or stripes to be incorporated into or onto security documents, and security documents having security threads or stripes. The security threads or stripes include i) first optically variable layer imparting a first different color impression at different viewing angles, ii) second optically variable layer imparting a second different color impression at different viewing angles, iii) first color constant layer having a color matching color impression of the first or second optically variable layer at a first viewing angle, iv) second color constant layer having a color matching color impression of the first or second optically variable layer at a second viewing angle, and v) a substrate. The layers are jointly visible from one side of the security thread or stripe.

In the field of protection of value documents and value commercial goods, the present disclosure relates to the field of security threads or stripes to be incorporated into or onto security documents, and security documents having security threads or stripes. The security threads or stripes include i) first optically variable layer imparting a first different color impression at different viewing angles, ii) second optically variable layer imparting a second different color impression at different viewing angles, iii) first color constant layer having a color matching color impression of the first or second optically variable layer at a first viewing angle, iv) second color constant layer having a color matching color impression of the first or second optically variable layer at a second viewing angle, and v) a substrate. The layers are jointly visible from one side of the security thread or stripe.

To provide a relief structure having a simple structure, capable of being manufactured with ease and at low cost, and capable of improving visibility, and a security medium having the relief structure.

A relief structure includes a grating structure part having a grating formed at a predetermined angle. The grating structure part includes a scattering structure part having a light scattering property.

Techniques for texture-based authentication of digital identity documents are disclosed. The disclosed techniques include authentication based on global texture information and/or on local texture information. Global texture-based authentication may include generating a global texture profile for an identity document image and comparing the global texture profile with a stored profile associated with a jurisdiction class of the identity document. Local texture-based authentication may include generating one or more local texture patches representative of texture information of one or more select local blocks of the ID. The one or more local texture patches are provided as input to one or more local detectors each trained to detect the presence of a forgery based on a target manipulation space.

Techniques for texture-based authentication of digital identity documents are disclosed. The disclosed techniques include authentication based on global texture information and/or on local texture information. Global texture-based authentication may include generating a global texture profile for an identity document image and comparing the global texture profile with a stored profile associated with a jurisdiction class of the identity document. Local texture-based authentication may include generating one or more local texture patches representative of texture information of one or more select local blocks of the ID. The one or more local texture patches are provided as input to one or more local detectors each trained to detect the presence of a forgery based on a target manipulation space.