Abstract: Moiré is an appealing visual effect observable when two or more repetitive patterns are superposed. We introduce a method for designing and fabricating level-line moirés on curved surfaces. These moiré shapes are obtained by superposing a partly absorbing or partly light deviating curved base layer and a curved revealing layer formed by a grating of transparent lines or cylindrical lenses. The distances between base layer and revealing layer are adapted to the locally varying distances between successive transparent lines or cylindrical lenses of the curved revealing layer grating. We demonstrate the quality of our method by rendered simulations and by fabrication. The resulting level-line moiré display devices can be manufactured using different fabrication techniques, from multi-material 3D printing to molding.

Abstract: Methods are disclosed for hiding a two-dimensional code such as a QR code within a visible layer of randomly scattered line segments. The scattering parameters comprise the length of successive line segments as well as their relative offsets. These parameters are stored in a key. The hidden 2d code is recovered with a computing device such as a smartphone carrying out the acquisition, perspective correction, and rectification of the visible layer of scattered line segments. This computing device synthesizes in its memory according to that same key a hidden layer of scattered line segments. The superposition of the acquired, perspectively corrected and rectified visible layer and of the hidden layer yields an image from which the hidden 2D code is revealed. The presented methods enable the secret transmission of information from the real world of documents and objects to databases located on computer networks.

Abstract: We disclose a method for printing by rotogravure, flexography, offset, inkjet or electrophotography invisible images that are viewable under UV light. The method generates juxtaposed dispersed dot halftones by first creating juxtaposed clustered dot halftones and by applying to them dispersed dot halftoning according to a blackness reduction factor. Dispersed dot halftoning is embodied by random threshold error diffusion. The resulting dispersed dot halftones comprise pixel segments located within the areas defined by the clustered dots. These pixel segments specify the areas of the cells to be engraved onto the rotogravure cylinder. For offset, they can be imaged onto an offset plate or for electrophotography, onto a photoconductor. The disclosed juxtaposed dispersed dot halftoning method can be embedded into a framework for the reproduction of fluorescent full color images with three or more invisible fluorescent inks. These invisible fluorescent color images offer a strong protection against counterfeits.

Abstract: Methods are disclosed for hiding a two-dimensional code such as a QR code within a visible layer of randomly scattered line segments. The scattering parameters comprise the length of successive line segments as well as their relative offsets. These parameters are stored in a key. The hidden 2d code is recovered with a computing device such as a smartphone carrying out the acquisition, perspective correction, and rectification of the visible layer of scattered line segments. This computing device synthesizes in its memory according to that same key a hidden layer of scattered line segments. The superposition of the acquired, perspectively corrected and rectified visible layer and of the hidden layer yields an image from which the hidden 2D code is revealed. The presented methods enable the secret transmission of information from the real world of documents and objects to databases located on computer networks.

Abstract: Moiré is an appealing visual effect observable when two or more repetitive patterns are superposed. We introduce a method for designing and fabricating level-line moirés on curved surfaces. These moiré shapes are obtained by superposing a partly absorbing or partly light deviating curved base layer and a curved revealing layer formed by a grating of transparent lines or cylindrical lenses. The distances between base layer and revealing layer are adapted to the locally varying distances between successive transparent lines or cylindrical lenses of the curved revealing layer grating. We demonstrate the quality of our method by rendered simulations and by fabrication. The resulting level-line moiré display devices can be manufactured using different fabrication techniques, from multi-material 3D printing to molding.

Abstract: The present invention proposes a method for producing an authenticable moiré shape that simultaneously moves and shows a beating effect. The method relies on a combination of the 1D or the 2D moiré and the level line moiré. When tilting a compound showing such a moiré, the moiré shape moves, its intensity levels change significantly but its shape remains the same and is recognizable. Embodiments comprise a base layer made of patterned metallic tiny shapes and a revealing layer made of a 1D array of cylindrical lenslets or of a 2D array of spherical or aspherical lenslets.

Abstract: The present invention proposes a method for producing an authenticable moiré shape that simultaneously moves and shows a beating effect. The method relies on a combination of the 1D or the 2D moiré and the level line moiré. When tilting a compound showing such a moiré, the moiré shape moves, its intensity levels change significantly but its shape remains the same and is recognizable. Embodiments comprise a base layer made of patterned metallic tiny shapes and a revealing layer made of a 1D array of cylindrical lenslets or of a 2D array of spherical or aspherical lenslets.

Abstract: The present disclosure describes a method and computerized means for creating dynamically evolving moiré shapes on curved surfaces. The method applies geometrical transformations in order to obtain curvilinear moirés and creates the moirés on curved surfaces by applying mappings from planar space to 3D space. The method relies on the superposition of a base layer with base bands and of a revealing layer with sampling elements. The dimensions of the revealing layer sampling elements such as cylindrical or spherical lenses as well as the distances between the base and revealing layer surfaces are adapted to the space between neighbouring isoparametric lines that define the curved surface. The resulting moiré shapes evolve smoothly on the specified curved surface and show recognizable shapes such as words, letters, numbers, flags, logos, graphic motifs, drawings, clip art, and faces.

Abstract: The present disclosure describes a method and computerized means for creating dynamically evolving moiré shapes on curved surfaces. The method applies geometrical transformations in order to obtain curvilinear moirés and creates the moirés on curved surfaces by applying mappings from planar space to 3D space. The method relies on the superposition of a base layer with base bands and of a revealing layer with sampling elements. The dimensions of the revealing layer sampling elements such as cylindrical or spherical lenses as well as the distances between the base and revealing layer surfaces are adapted to the space between neighbouring isoparametric lines that define the curved surface. The resulting moiré shapes evolve smoothly on the specified curved surface and show recognizable shapes such as words, letters, numbers, flags, logos, graphic motifs, drawings, clip art, and faces.

Abstract: The present disclosure describes an authentication and tracking system relying on spatial codes hidden into a grayscale, variable intensity or color multigrating reproduced on a substrate. The authentication software running in a smartphone takes pictures of the multigrating and applies perspective correction and fine grain rectification. The hidden spatial code is made apparent by the phase-controlled superposition of the fine grain rectified multigrating and a corresponding digital revealing layer grating. Subsequent image processing operations enable extracting the hidden spatial code, decode it and authenticate the corresponding document or good, by sending the decoded message to an authentication and tracking computing server. Applications include the authentication and tracking of documents and goods as well as the localization of persons.

Abstract: We disclose a method for synthesizing by computer an artwork where 2D and 3D contents are integrated within a same composition. Such an artwork creates plausible effects for the viewers by showing a different relationship between 2D and 3D at each viewing angle. Methods are proposed for ensuring the continuity between the 2D and the 3D parts in terms of mesh geometry and reflected colors. The user selects from a given scene a region of interest (ROI) to be reproduced in 3D. A flat rendering grid is created that matches the topology and tesselation of the ROI. The ROI is attached to the rendering grid. To enhance the continuity between the 2D and the 3D parts of a scene object, the 2D part of the object can be represented as bas-relief. Designers can create 2D-3D sculpture paintings for decoration, exhibitions, and homes.

Abstract: We disclose a method for synthesizing by computer an artwork where 2D and 3D contents are integrated within a same composition. Such an artwork creates plausible effects for the viewers by showing a different relationship between 2D and 3D at each viewing angle. Methods are proposed for ensuring the continuity between the 2D and the 3D parts in terms of mesh geometry and reflected colors. The user selects from a given scene a region of interest (ROI) to be reproduced in 3D. A flat rendering grid is created that matches the topology and tesselation of the ROI. The ROI is attached to the rendering grid. To enhance the continuity between the 2D and the 3D parts of a scene object, the 2D part of the object can be represented as bas-relief. Designers can create 2D-3D sculpture paintings for decoration, exhibitions, and homes.

Abstract: We present a method for hiding images in synthetic videos and reveal them by temporal averaging. We developed a visual masking method that hides the input image both spatially and temporally. Our masking approach consists of temporal and spatial pixel by pixel temporal variations of the frequency band coefficients representing the image to be hidden. These variations ensure that the target image remains invisible. In addition, by applying a temporal expansion function derived from a dither matrix, we allow the video to carry a visible message that is different from the hidden image. The image hidden in the video can be revealed by software averaging, or with a camera, by long exposure photography. The method finds applications in the secure transmission of digital information.

Abstract: The present invention describes methods and apparatuses for creating superposition shape images by superposed base and revealing layers of lenslet gratings. The superposition shape images form a message recognizable by a human observer or by an image acquisition and computing device such as a smartphone. The superposition shape images may be created by different superposition techniques ranging from 1D moiré, 2D moiré and level-line moiré superposition techniques to lenticular image and phase shift superposition techniques. Moiré superposition techniques enable creating superposition shape images at different apparent depth levels. Applications comprise the protection of documents and valuable articles against counterfeits, the creation of eye-catching advertisements as well as the decoration of buildings and exhibitions.

Abstract: We propose new methods for creating color varying prints with classical cyan, magenta, yellow inks on a metallic specularly reflecting or on a white diffusely reflecting substrate. We use a special cross-line halftone with optimized surface coverages of the inks to create cross-halftone prints whose colors change when rotating the print in-plane under specular reflection. These prints enable viewing at the same location a first image with a first set of colors and upon in-plane rotation of the print or displacement of the observer, a similar or a different image whose parts are colored with a different set of colors. Applications comprise counterfeit prevention, art, advertisement, decoration, exhibitions and surprising displays in amusement parks.

Abstract: We propose new methods for creating color varying prints with classical cyan, magenta, yellow inks on a metallic specularly reflecting or on a white diffusely reflecting substrate. We use a special cross-line halftone with optimized surface coverages of the inks to create cross-halftone prints whose colors change when rotating the print in-plane under specular reflection. These prints enable viewing at the same location a first image with a first set of colors and upon in-plane rotation of the print or displacement of the observer, a similar or a different image whose parts are colored with a different set of colors. Applications comprise counterfeit prevention, art, advertisement, decoration, exhibitions and surprising displays in amusement parks.

Abstract: We propose new methods for creating color varying prints with classical cyan, magenta, yellow inks on a metallic substrate. We use a special crossline halftone with optimized surface coverages of the inks to create color prints on a metallic surface whose colors change when rotating the print in-plane under specular reflection. These prints enable viewing on the same metallic print a first image with a first set of colors and upon in-plane rotation, the same image with parts colored with a different set of colors. They also enable viewing a first color image and upon rotation a second independent color image. Applications comprise counterfeit prevention, art, advertisement exhibitions and amusement parks.

Abstract: We propose new methods for creating color or achromatic images that are printed with classical cyan, magenta, yellow and a white diffusing ink on a metallic substrate. We optimize the surface coverages of the cyan, magenta, yellow and white inks in order to create color prints on a metallic surface that look bright and colorful under specular reflection and also look good under non-specular observation conditions. We also provide new means for the prevention of counterfeits. A first effect enables viewing on the same metallic print one achromatic image in specular viewing mode and a second independent achromatic image in non-specular viewing mode. The second effect enables hiding a pattern such as text, graphics or a grayscale image within the printed color image in one viewing mode, specular or non-specular and showing that pattern in the second viewing mode, non-specular or specular, respectively.

Abstract: A method and computing system are proposed for producing an authenticable security device with two sides. The verso side is covered with an adjustable luminescent emissive layer formed by invisible luminescent ink halftones and possibly a UV absorbing printed layer. The recto side is covered with transmissive non-luminescent ink halftones. The backlit colors resulting from the emissions of the luminescent layer or resulting from illumination by normal white light through the transmissive non-luminescent ink halftones are predicted by a backlighting model. This model enables computing the surface coverages of the luminescent and/or non-luminescent ink halftones in order to obtain a desired color either under excitation light (UV light) or under normal white light. This enable creating authenticable backlit images substantially similar to pre-stored reference images, either under normal white light, under excitation light, or under both the normal white light and the excitation light.

Abstract: A method and computing system are proposed for producing an authenticable security device with two sides. The verso side is covered with an adjustable luminescent emissive layer formed by invisible luminescent ink halftones and possibly a UV absorbing printed layer. The recto side is covered with transmissive non-luminescent ink halftones. The backlit colors resulting from the emissions of the luminescent layer or resulting from illumination by normal white light through the transmissive non-luminescent ink halftones are predicted by a backlighting model. This model enables computing the surface coverages of the luminescent and/or non-luminescent ink halftones in order to obtain a desired color either under excitation light (UV light) or under normal white light. This enable creating authenticable backlit images substantially similar to pre-stored reference images, either under normal white light, under excitation light, or under both the normal white light and the excitation light.