Abstract: Provided are a method, system, and program for generating threshold values in a dither matrix. A dither matrix of threshold values is generated.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: 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 3×3 pixels).

Abstract: 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.

Abstract: A data processing system and method are described for generating a halftone screened image from an input image. A first threshold matrix is generated which, when utilized to halftone a solid gray input image, generates a first halftoned output image which is a plurality of generally solid vertical lines. The first threshold matrix includes a plurality of matrix elements arranged in a plurality of rows and a plurality of columns. A plurality of groups of the matrix elements are shifted within the first threshold matrix to create a second threshold matrix which, when utilized to halftone the solid gray input image, generates a second halftoned output image which is a checkerboard type pattern of alternating black or white blocks. In one embodiment, groups of the plurality of the rows are shifted horizontally over by at least one adjacent column to generate the second matrix.

Abstract: A method, computer program product, and a program storage device readable by machine, for repurposing images includes classifying the pixels of a binary image as being either halftone image pixels or non-halftone image pixels, further processing the halftoned image pixels with halftone image pixel processing and combining the outputs of the halftone image pixel processing and non-halftone image pixel processing to prepare the images for a second purpose such as a second printer. The processing that classifies the binary pixels as being either halftone image pixels or non-halftone image pixels segments the image into regions of halftone image pixels and regions of non-halftone image pixels. The processing of regions of halftone image pixels first constructs an intermediate gray scale representation of the regions of halftone image pixels.

Abstract: A digital halftoning technique for controlling a spot function to address gear noise, printer stress, and general print quality 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. The resulting non-separable shape-changing spot function can reduce printer stress and improve print quality.

Abstract: 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.

Abstract: 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.

Abstract: A system and process by which misregistration among the pixel components of the several color planes of a color image can be substantially eliminated is presented. In an embodiment, the physical object which comprises the test scene is represented as having features that are uniform squares of alternating black and white color arranged. The digitized color image of the test scene is employed to make measurements of misregistration of scene features in its color planes. A process by which misregistration among the several color planes is measured, and substantially eliminated, is made up of three parts. First, one of the color planes is chosen as a reference plane. The remainder of the color planes are called secondary planes. The relative misregistration of image features in the secondary planes relative to corresponding image features in the reference plane are measured at dispersed pixel locations in the reference plane.

Abstract: A method and an apparatus to descreen a halftoned picture takes into account the actual distribution of black or colors on the print without the need for scanning printed images but, rather, using only the printing decision matrix and the printer characteristics. For the purpose of laser printing, or more generally for reproduction on any printing device with a limited number of printing levels, a color or grayscale image has to be transformed into an array of printing decisions at each pixel of the output image. Sometimes this array is the only available representation of the original image. One may desire to reconstitute a good approximation of the original grayscale image from this array, for instance to print the picture on a printer with different characteristics from the printer for which the array was originally prepared, or to display it on a high resolution monitor. The method and apparatus to solve this problem in a way which take precise account of printer characteristics is described.

Abstract: A method and apparatus for halftoning utilizes a truly aperiodic mask with memory requirements much smaller than the mask itself. The mask is constructed of several smaller compatible masks and a selector which selects between the smaller masks. In this way the computation of a large aperiodic mask is replaced by the computation of several much smaller masks. Using this technique, watermarks may be embedded for encrypting information in such a way that the quality of the image is not compromised.

Abstract: A method and apparatus for matching the print outputs of two printers having different characteristics. For the purpose of laser printing, or more generally for reproduction on any printing device with limited number of printing levels, a color or grayscale image has to be transformed into an array of printing decisions at each pixel of the output image. Sometimes this array is the only available representation of the original image. One may desire to print this array on a printer with different characteristics from the printer for which the array was originally prepared. The method and apparatus solve this problem by generating a printing decision matrix which takes into account the differences between the two printers.

Abstract: A technique which combines the advantages of blue noise and clustering obtains more pleasant "blueish" effects in the rendering of the grey levels for which the original multicell mask generates unwanted periodic representations. Such original multicell clustered dither array patterns which are undesirable are replaced by less periodic ones while preserving all benefits of the classical methods, and in particular, leaving the nicest patterns unchanged. An automated process redistributes the locations of the threshold values corresponding to undesirable grey levels to obtain more pleasant "blueish" effects in the rendering of the grey levels.