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: Methods are proposed for visually evenly spacing of two successive characters taking into account outline shape modifications induced by character grid-fitting. Visually even spacing of characters is obtained by converting the geometric space between two characters into its visually perceived equivalent space. Converting between geometric and visually perceived spaces requires transformations applied to the character outlines for smoothing out the character borders and replacing them by virtual borders which represent the boundaries of the perceived intercharacter space. The optimal visual distance between the origins of two successive characters is obtained by requiring the characters to have a perceived visual space equal or close to an ideal perceived visual space called ideal optical intercharacter space extracted from by design optimally spaced character pairs such as "nn" for lower-case characters and "HH" for capital letters.