Abstract: What is provided herein are systems and methods for digitally reproducing a moiré-free color halftone image using an enhanced halftone screen set consisting of a halftone screen for each of N colorants, where N>4. Also disclosed is an enhanced color halftoning screening apparatus for reproducing a moiré-free color halftone image using an enhanced halftone screen set consisting of a halftone screen for each of N colorants, N>4. Further disclosed are embodiments for generating a plurality of non-orthogonal halftone screen outputs for moiré-free enhanced color halftoning.

Abstract: Disclosed herein is a method and apparatus for moiré-free color halftone printing with up to four color image separations. The method and apparatus utilize a plurality of non-orthogonal halftone screens to produce outputs that are moiré free and form uniform periodic rosettes. The method and apparatus provide for defining a first and a second color halftone screen fundamental frequency vector for each of three halftone screens such that the halftone screen set output forms uniform hexagonal rosettes; then defining a fourth color halftone screen where a first fundamental vector of the fourth screen shares a fundamental frequency vector with one of said three halftone screens and a second fundamental frequency vector of the fourth screen shares a fundamental frequency vector with a different one of said three color halftone screens.

Abstract: Method for duplex printing on transparencies to create auto-stereoscopic enhancement to rendered images. On one side of the transparency is provided a uniform halftone with a selected median spatial frequency as printed. On the other side, the image for enhanced rendering consisting of two partitions is printed: that partition which is to be perceived as the background is printed using a halftone with spatial frequency equal to the median plus some delta x, while the other image partition is printed using a halftone with a spatial frequency equal to the median minus the same delta x. The spatial frequency difference creates a corresponding shift-magnification factor M with an amplified total depth of the shift-magnification factor M times the thickness of the transparency.

Abstract: What is disclosed is a system and method for efficiently and accurately estimating the complete TRC for a color marking device equipped with a multi-center cluster halftone screen which has a similar halftone tiling geometry and a similar growth specified by a corresponding single-center cluster halftone screen. The present method introduces a cluster-based printer model which establishes a relationship between a color output of a single-center cluster halftone screen and a color output of a multi-center cluster halftone screen. The present cluster-based printer model determines the complete TRC for the multi-center cluster halftone screen using the measurements for the single-center cluster halftone screen. Results of halftone dot linearization with different printing devices demonstrates that high accuracy can be achieved using the reduced measurements from the single-center cluster halftone screen.

Abstract: An apparatus and method are provided for processing a digital image to determine whether the image includes a region of differential gloss (which would yield a differential gloss when that digital image is printed into hardcopy). The method includes identifying whether an input digital image has a periodic characteristic which is indicative of a cluster screen halftoned digital image and, if so, determining a correlation between first and second filters and halftone structures of the identified digital image. The second filter has a different polarization from the first filter. The first and second filters are selected to enable a region of differential gloss in the identified digital image to be identified, based on the determined correlations. Where such a region or regions are detected, a representation of the differential gloss image may be displayed and/or another action automatically initiated, such as restricting printing of the image.

Abstract: A process for improving the reconstruction of images compressed by the wavelet-based JPEG2000 specification. The basic reconstruction is followed by an edge-preserving filter (such as a sigma filter), another transform to the wavelet domain, an adjustment in the wavelet domain to yield the same quantized values as the compressed input image, and, finally, an inverse wavelet transform to yield the improved image. The process reduces the artifacts in sharp text and graphics documents, yielding images that would otherwise require larger files.

Abstract: The present invention relates to the expedient supply of differential gloss text into a document image, particularly as when desired in the employ of rendering variable data. A font character is selected and sub-sampled. The sub-sampled result is then scaled up into a full size result. A first halftone cell having a first anisotropic structure orientation is selected and applied to the full size scaled font result while a second halftone cell having a second anisotropic structure orientation is applied to the surrounding background around the full size scaled font result to create a gloss font character. This full gloss font character is then stored as a font representation as callable by the digital front end of a printing apparatus.

Abstract: Systems and method for digitally reproducing a moiré-free color halftone output image having an embedded correlation-based digital watermark are provided using an enhanced halftone screen set consisting of a halftone screen for each of N colorants forming N color separations (where N?3). The N different uniform rosette halftone screen configurations are generated such that each meets uniform rosette halftone screen conditions. A corresponding three-dimensional threshold array is generated for each halftone screen configuration having a phase shift value as an input. The color input image is halftoned, halftoning each one of the N different color separations using a corresponding halftone screen configuration and three-dimensional threshold array to form a moiré-free color output image having the correlation-based digital watermark embedded therein. A single key can be used to produce a full color image of the output image having the watermark image visible therein.

Abstract: The present invention relates to the expedient supply of differential gloss or other correlation mark text into a document image via a font definition, particularly as when desired in the employ of rendering variable data. A font character is selected and sub-sampled. The sub-sampled result is then scaled up into a full size result. A first halftone cell having a first anisotropic structure orientation is selected and applied to the full size scaled font result while a second halftone cell having a second anisotropic structure orientation is applied to the surrounding background around the full size scaled font result to create a gloss font or other correlation mark character. This full gloss font character or correlation mark character is then stored as a font representation as callable by the digital front end of a printing apparatus.

Abstract: A variable data pantograph is formed by receiving a variable data string and retrieving at least one character representation from a vocabulary of character representations stored in memory. The retrieved at least one character representation corresponds to the variable data string. Each of the character representations in the vocabulary include a foreground region including a character shape and a background region suitably sized and arranged for encompassing the foreground region. The background region incorporates a first pattern of elements and the foreground region incorporates a second pattern of elements. The retrieved at least one character representation is assembled to form a variable data pantograph, whereby when the variable data pantograph is rendered in an original document, the foreground and background regions are similar in tone, the foreground and background regions being substantially less similar in tone in a copy of the original document to render the character visible.

Abstract: Various implementations of this invention provide a method of color transformation of image data that included: providing at least two units, each unit comprising a combination of a plurality of look-up tables and a M×N matrix; providing image data configured in a first color space; processing the image data using a first unit to generate an output; and processing the generated output using a second unit to generate a second output; wherein the plurality of look-up tables are used to transform an input color space to a device dependent color space, and the M×N matrix is used to perform one of at least converting color data defined in standard space to data defined in XYZ space and converting image data defined in XYZ space to image data defined in LAB space.

Abstract: A method for encryption of a digital watermark by intelligent halftoning includes receiving image data that define at least a portion of a document to be printed in terms of at least three halftone images corresponding respectively to three printing colorants, each of the three halftone images comprising a plurality of halftone cells. The image data are modified by phase-shifting some of the halftone cells of at least one of the halftone images relative to the other halftone images to encode a watermark within the portion of the document such that the at least one phase-shifted halftone image includes a phase-shifted region and a non-phase-shifted region. The modified image data are used to print the portion of the document on a substrate that will fluoresce when subjected to UV illumination. The printed portion of the document includes a first printed pattern resulting from the phase-shifted region and a second printed pattern resulting from the non-phase-shifted region.

Abstract: A fluorescence-based correlation mark is included in a printed document by encoding the correlation mark as phase shifts in the yellow halftone image only of a printed color document. The correlation mark transparency key is likewise printed using only yellow colorant or can be printed in black or with another colorant or mixture of colorants that will appear dark or black when subjected to UV illumination. UV illumination of the document without use of the transparency key, and use of the transparency key without UV illumination of the document are insufficient to reveal the fluorescence-based correlation mark. UV illumination of the document while the transparency key is overlaid with the document will allow the correlation mark to be perceived.

Abstract: Disclosed herein is a Moiré-free color halftone configuration for clustered dots. Unlike conventional methods, the disclosed method produces periodic hexagon rosettes of identical shapes. These exemplary hexagon rosettes have three fundamental spatial frequencies exactly equal to half of the fundamental frequency of the three halftone screens. The resultant halftone outputs are truly Moiré free, as all the fundamentals and harmonic frequencies are multiples of and thus higher in frequency than the rosette fundamental frequency. The halftone outputs resulting from the employment of the exemplary rosette design methodology provided herein, are also robust to the typical misregistration among color separations commonly found in color systems.

Abstract: A method for enhancing color fidelity in multi-reproduction, includes scanning an image to be reproduced, wherein the image contains an invisible digital watermark including color information; decoding the color information contained in the watermark; comparing the decoded color information with the scanned image; generating a correction table from the differences between the decoded color information and the scanned image; and performing color correction on the scanned image using the correction table. This method confines the color error to one generation, even when copies go through multiple reproduction.

Abstract: Disclosed are systems and methods directed to digital watermarks, and more particularly, the generation of invisible correlation-based digital watermarks embedded in halftone images.

Abstract: Disclosed are systems and methods directed to the generation of digitally watermarked grayscale images having a watermark embedded at different arbitrary Rotation Angles. A single public key can be used to retrieve the otherwise invisible watermarks from the watermarked images when overlaid atop the images at Orientation Angles corresponding to the Rotation Angles.

Abstract: Disclosed are systems and methods directed to the generation of multi-layer digital watermarks, including the generation of distinct watermarks on each of at least two color layers or channels within an image such that each may be retrieved or viewed independently of the other in the output image.

Abstract: A method and apparatus are provided for compensating for spatial non-uniformities in a printer by deriving a true spatial non-uniformity tone response curve (TRC) that characterizes the printer in terms of color output variation for each addressable pixel location in a spatial range. In a one-time offline process, the “true average” tone response curve is determined for a color channel and stored. The “true average” tone response curve defines an average true response for the printer across the printed output spatial range. A prediction of the true response as a function of the spatial location is derived by printing and scanning a specially designed halftone-independent target of binary patterns. The predicted tone response curve for each color channel and halftone is predicted using a binary printer model and stored, wherein the “predicted tone response curve” provides a model based approximation of the actual response for the printer for each addressable pixel location in the spatial range.

Abstract: Disclosed herein is a Moiré-free color halftone configuration for clustered dots. Unlike conventional methods, the disclosed method produces periodic hexagon rosettes of identical shapes. These exemplary hexagon rosettes have three fundamental spatial frequencies exactly equal to half of the fundamental frequency of the three halftone screens. The resultant halftone outputs are truly Moiré free, as all the fundamentals and harmonic frequencies are multiples of and thus higher in frequency than the rosette fundamental frequency. The halftone outputs resulting from the employment of the exemplary rosette design methodology provided herein, are also robust to the typical misregistration among color separations commonly found in color systems.