International Business Machines Corporation

Infoprintsolutions Company, LLC

Gerhard Robert Thompson

Chai Wah Wu

Ravishankar Rao

Mikel J Stanich

Charles Philippe Tresser

Hong Li

Joan LaVerne Mitchell

Steven Lorenz Wright

James Thomas Smith, Ii

Joseph Stanley Czyszczewski

Danielle Kathryn Dittrich

Kuo Chung-Hui

Larry Mason Ernst

Nenad Rijavec

Ravinder Prakash

Yue Qiao

Ho Chong Lee

Frederick Cole Mintzer

James Edward Christensen

Jack Louis Zable

Gordon Wesley Braudaway

Marco Martens

Jennifer Quirin Trelewicz

John E Campbell

Gerald Goertzel

Roy Lee Adler

Steven Edward Millman

Kenneth C Ho

Richard Ian Kaufman

Paul F Greier

Fritz H Obermeyer

Danielle Kathyrn Dittrich

Charles H Morris, Iii

Dan R Kaufman

Charles Philipe Tresser

Chungkui Kuo

Charles B Tresser

Huy A Nguyen

Provided are a method, system, and program for generating threshold values in a dither matrix. A dither matrix of threshold values is generated. The threshold values in the dither matrix are filtered to generate a filtered dither matrix of filtered dither values by performing for dither values in the dither matrix: determining a region of dither values in the dither matrix that surrounds the value being considered, wherein the dither values in the determined region comprise one of dither values in a first portion of the region within the dither matrix or a wrap around dither value in a second portion of the region that extends beyond the dither matrix; and using an offset value to determine one wrap around dither value, wherein repeated instances of the dither matrix are designed to be applied to an image by forming a tile pattern of the repeated instances of the matrix over the image pattern, and wherein the repeated instances of the matrix in the tile pattern are offset in one direction by the offset value; and performing an operation on the determined dither values in the region to determine a filtered value for the dither value being considered.

Generating threshold values in a dither matrix

A method (and system) of multi-bit halftoning includes comparing values of an image to threshold values of a halftone threshold matrix, and generating output values that provide a greater than minimum level of contrast.

System and method for multi-bit halftoning

A method and system for generating halftone tables, using a spot function, subdivides the pixels within the halftone cell of a halftone matrix into a plurality of sub-pixels, determines the value of the spot function corresponding to the position of each of the sub-pixels within the halftone matrix, repeats the subdividing and determining for all of the sub-pixels in the halftone matrix, ranks the values for the entire halftone matrix, normalizes the ranked values, generates a cumulative histogram based upon the normalized values, and stores the cumulative histogram as a halftone table.

Method and system for designing multilevel halftone screens using spot functions

A system and method for capturing and scaling images includes a scaling engine with the ability to employ a first scaling factor in a first direction and a second scaling factor in a second direction. In addition, the preferred scaling engine manipulates the scaling process so that the scaling calculations are performed using fixed point arithmetic. The preferred scaling engine preserves isolated features such as a single white pixel in a field of black pixels and vice versa. Improved readability is achieved in one embodiment by performing the scaling process multiple times using different degrees of 'padding' where padding refers to the technique of surrounding an image with a perimeter of one or more blank (white) pixel elements.

Black white image scaling for optical character recognition

A multiple beam printer system having N laser beams receives print job information from a print host. A rendering application uses a threshold array to generate halftone image data from the print job. The threshold array is defined based on a spot function. The defined screen is non-orthogonal and includes Y pels in a direction that is perpendicular to a scanning direction of the laser beams where Y is an integer multiple of N. A distance between screen dots in pels is preferably equal to an integer multiple of N. The screen dot may be defined by a supercell encompassing two screen dots and having an odd number of pels in a direction that is parallel to the scanning direction. The spot function may include a snap feature that snaps a screen dot to the nearest printer grid pel. The spot function may include scaling to compensate for the distortion of the non-orthogonal screen dot.

Bandless halftone design for multiple beam printers employing non-orthogonal halftones

A halftone spot function, for determining a shape of a halftone spot as a function of the intensity of an image being printed, is generated by creating one or two line segments forming a part of the shape of the spot function or by creating a number of contour lines that are interpolated to form the function. A halftone spot pattern is generated as a number of supercells, each of which includes a number of halftone spots, each defined within a halftone spot cell by a halftone spot function, with the supercell being defined to include a number of device pixels, each of which is fully inked of left without ink, a number of spot cells in each direction, and offset distance establishing angles of the lines dividing the spot cells from one another.

Method and system for specifying halftone spot shapes

Techniques for generating dither masks are provided. A dither mask is generated by selecting a sequence of at least three original patterns comprising pixels of at least one of a first color and a second color. At least two patterns are interpolated to generate interpolated patterns in the sequence between the at least three original patterns. If a pattern having at least one specified characteristic exists in the sequence, the steps of interpolating between at least two patterns, and determining if a pattern having at least one specified characteristic exists in the sequence, are repeated. The interpolation is between at least one pattern from each side of the pattern having at least one specified characteristic in the sequence.

Methods and apparatus for generating dither mask through interpolation between preferred patterns

A method, computer program product and system for detecting and compensating for color misregistration. A black/white edge or a solid color edge on a target may be scanned. A black/white edge may refer to a black image, e.g., black text, on a white surrounding background having a rapid spatial transition from black to white. A solid color edge may refer to a solid color image, e.g., solid color text, on a white surrounding background having a rapid spatial transition from color to white. A curve of gray values versus spatial pixel positions for each color channel, e.g., red, green and blue color channels, may be generated. A misregistration error may then be calculated by calculating the offset between the color channel curves. The misregistration error may then be used to calibrate the scanner to compensate for the detected color misregistration.

Detecting and compensating for color misregistration produced by a color scanner

A method of embedding an image into two images by performing a digital halftoning process on a Cartesian product of color spaces to embed the image into the two images. A digital halftoning process includes an iterative isotropic halftoning process. The iterative isotropic halftoning process for each iteration if Outimage has not changed between two iterations or maximum number of iterations reached, then exit the iterations loop.

Method and system for embedding an image into two other images

A digital halftoning technique for controlling a spot function is disclosed. A method for generating a spot for use in halftoning according to the present invention includes defining a spot function that combines two functions selected to provide a predetermined spot shape for use in a halftone cell and scaling the spot function using a scaling function that varies according to a value of a first and second spot function ordinate. Asymmetric modulation of spot functions is used to control the touching of adjacent spots, and to change the shape of the spots with the gray region.

Method and apparatus for controlling a spot function for digital halftoning

Provided is a method, system, and program for managing a multi-page document. A plurality of input files are received including digital representations of multiple pages of a document. The content of each entire page is represented in a first representation format. The entire page content is capable of including content of a first content type and second content type. For each page of the document represented in the input files, a determination is made of regions in the page including content of the second content type. Each determined region in the page is processed to generate the content for each region in a second representation format. The content of the entire page in the first representation format and the content of each region in the second representation format is added to at least one output file. The output file is then stored.

Method, system, and program for managing a multi-page document

Provided is a method, system, program, and data structures for halftoning an input image comprised of at least two input color components. Each input color component provides input intensity values for the color component at pixel locations in the image. At least two halftoning screens are accessed. There is one screen for each color component and halftone output generated by at least one of the screens has a lines per inch (LPI) that is at least approximately twenty percent different than the LPI of halftone output generated by one other screen. The input image is separated into the separate color components. The accessed screen for each color component is applied to the input intensity values for the color component to produce output intensity values for the color component. The combined halftone outputs for all the color components form the output pixels.

Method, system, program, and data structures for halftoning with line screens having different lines per inch (LPI)

A digital imaging system and method uses a two-stage sigma filter to de-screen color images. This filter does not assume any a priori knowledge about the screening process using to produce the halftone image. The two-stage sigma filter may therefore be used to convert color halftone images into continuous-tone images irrespective of the screening process used. The two-stage sigma filter may be constructed, or emulated in software, using an O (N) algorithm which performs smoothing and preserves edge information simultaneously in the Red/Green/Blue color space. This system and method outperforms conventional approaches which, for example, use a Gaussian blur, because it satisfies the dual criteria of completely eliminating halftone screens while preserving edge information. When combined with halftone segmentation techniques, a complete document processing algorithm for gray-scale and color documents is created.

De-screening halftones using sigma filters

The present invention presents halftoning techniques for printers and solves problems related to halftoning so as to render a combination of text and image areas in a pleasing manner. An advantage of this technique is that it gradually switches from text rendering to picture rendering in a manner which is locally adaptive over small regions, (say 3&#xd7;3 pixels).

Priority-driven dither

A method (and system) for producing a halftoned image, includes calculating errors corresponding to a plurality of different viewing conditions of a halftone image, and minimizing a function of the errors, such that the halftoned image appears as a different image under different viewing conditions. Alternatively, in another embodiment, the halftoned image appears as the same image under different viewing conditions.

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Wappingers Falls, NY, United States of America

Gerhard Robert Thompson