Abstract: A parallel, non-iterative, memory efficient method of determining image skew. A document skew angle is determined from a fast scan second order moment data set and a slow scan second order moment data set. A slow scan second order moment data set can be generated by receiving a current scanline of image data, updating columns sums for a set of rotation angles using scanlines within a buffer comprising a band having a predetermined number B of scanlines, and updating the buffer with the current scanline.

Abstract: A method for operating a printing machine to maintain developer material within in a predefined state by monitoring the state of materials in a developer and automatically scheduling corrective action before print quality becomes significantly impacted. The corrective action can include forcing an increase in toner usage by periodically generating and developing images having high toner density.

Abstract: A background detection process that analyzes background information for the purpose of limiting the impact of intensity information obtained from non-document areas includes: identifying a first white peak from pixels within a first document region; identifying a second white peak from pixels within a second document region; determining if the first white peak was identified using image data from outside of the input document; and if so, identifying a third white peak from pixels within the first document region based on the second white peak.

Abstract: A method for processing segmentation tags to generate a block level tag representative of a group of segmentation tags includes identifying a block of the segmentation tags; compiling a block statistic from a plurality of segmentation tags within the block; determining a most predominant segmentation tag and a second most predominant segmentation tag in the plurality of segmentation tags; and generating a block level tag for the block based on the most predominant segmentation tag, the second most predominant segmentation tag and the block statistic.

Abstract: A method to compensate for dot placement errors includes receiving image data comprising a plurality of pixels, each having at least two states, a first corresponding to depositing no ink and a second corresponding to depositing ink; identifying a stray pixel pattern within the image data, the stray pixel pattern including a stray pixel corresponding to a misplaced dot in a dot pattern; and modifying the image data corresponding to the stray pixel pattern by setting the stray pixel to the first state and changing a second pixel from the first state to the second state.

Abstract: A method for identifying document edges collects a predetermined number scanlines of the document. Both first order and second order statistics are then calculated based on the scanned data. A first slope value being a function of the difference between a plurality of the first value and a second slope value being a function of the difference between a plurality of the second value are calculated. A document edge is detected using the first and second slope values.

Abstract: An adaptive image enhancement filter includes a template matching module for comparing an observed pixel pattern comprising a target pixel and one or more neighboring pixels to a set of templates to determine if the observed pixel pattern matches any of the templates. The template matching module generates a match identifier signal indicating which of the templates, if any, the observed pixel pattern is found to match. Based on this match identifier, a signal generation module provides an enhanced output signal for the target pixel. The template matching and/or the signal generation modules can be independently modified to adapt to changing conditions as identified by signals identifying image attributes and marking process attributes.

Abstract: A method for calibration of touchscreen display coordinates includes displaying a calibration target; sensing a calibration touch for the calibration target; obtaining a calibration touchpoint coordinate for the calibration touch; determining if the calibration touchpoint coordinate is valid; and if so, storing the calibration touchpoint coordinate in a touchpoint history database and using calibration touchpoint coordinates to define a calibration reference point for operation, otherwise generating a computed reference calibration point as an average of using a predetermined number of the calibration touchpoint coordinates in the touchpoint history database.

Abstract: The present invention is a method and apparatus for improving the appearance of electronic images, and more specifically, to the efficient use of template rotation within a template matching process to enhance such images. The invention reduces the number of entries that are stored in a look up table by eliminating identical patterns that differ only by the angle at which they are output. The appropriate templates are then rotated it by the required angle for output subsequent to their retrieval from the lookup table.

Abstract: A method for characterizing a printing device response for a halftone screen includes (a) generating a plurality of test patches, each test patch comprising a dot pattern having less than three different base patterns for the halftone screen; (b) measuring the luminance of selected ones of the test patches; (c) plotting the luminance measurements to provide a set of calibrated points on a printer calibration curve; and (d) generating the printer calibration curve between adjacent calibrated points using an equation establishing a relationship between ink area coverage and reflectance of the image.

Abstract: A method and apparatus for multi-level color error diffusion employs semi-vector quantization. When operating on image data comprising three color separations, the method employs a vector quantization for the two separations with the most visually perceptive color output to generate a multi-level output pixel for each separation based on the sum and a difference of the input pixel values for the two separations. The method generates multilevel output pixels for the third color separation using scalar error diffusion.

Abstract: A system and method for determining the registration parameters necessary for registration or edge detection processing to enable the flexibility of changing the color of backing to suit a given application. The method includes scanning the backing surface to obtain at least two sets of gray level values; (b) determining an average gray level for each of the two color channels; (c) selecting a registration channel based on the average gray level; (d) determining a gray level deviation for the registration channel; and (e) determining registration parameters based on the average gray level and the gray level deviation of the registration channel.

Abstract: A method for identifying document edges collects a predetermined number scanlines of the document against a light backing and a dark backing. A first set of first-order statistics are calculated from the image data obtained by scanning the document against the light backing. A second set of first-order statistics are calculated from the image data obtained by scanning the document against the dark backing. A document edge is detected using the first and second sets of first-order statistics.

Abstract: A method of reproducing a document including halftoned regions therein scans the document to generate scanned image data comprising a digitized representation of said document. The scanned image data that corresponds to the halftoned regions is then rendered using a compact rendering process that includes positioning an observation window about a target pixel and a neighboring pixel; selecting a fill-order based upon a result of the analyzing step; and generating a high addressability pixel as a function of the selected fill-order.

Abstract: A method for generating a background statistics that distinguishes between gray level information from document areas and non-document areas. The method includes determining a full page background statistics from selected pixels within a scanned area; determining a sub-region background statistics from selected pixels within a sub-region of the scanned area; determining if the sub-region background statistics corresponds to image data from a non-document area; determining if the full page background statistics is corrupted; and generating a validated full page background statistics if the full page background statistics is corrupted.

Abstract: A system and method for method of cleaning segmentation tags is disclosed. A method in accordance with the present invention comprises receiving a plurality of segmentation tags; generating block level tags in response to the received segmentation tags wherein each block level tag is a representative tag for a block of received segmentation tags; and cleaning selected ones of the received segmentation tags using a window of neighboring block level tags.

Abstract: An improved sliding window dictionary-based compression method limits the data within the sliding window searched to data strings occurring at each discrete match location within a plurality of predefined discrete match locations, the plurality of predefined discrete match locations comprising a set of non-continuous data positions within the window of data.

Abstract: A method for scanning a document includes: acquiring scanned image data from a first region of the document; determining an initial estimate of a document attribute using pixels in the first region; acquiring scanned image data from a second region of the document; processing pixels in the second region in accordance with the initial estimate; determining a second estimate of the document attribute using selected pixels in the second region; determining if the initial estimate is valid and if not, processing pixels within the image in accordance with the second estimate.

Abstract: A system and method of processing segmentation tags is disclosed. In accordance with the present invention, a method for processing segmentation tags that receives blocks of segmentation tags each of which has an associated block level tag that is representative of the segmentation tags within the block. The method positions a neighborhood window about a current block and a neighboring block and cleans a target segmentation tag within the current block based upon the block level tags within the neighborhood window using a set of tag cleaning rules.

Abstract: An apparatus for steering a moving web, particularly in an electrophotographic printing machine of the type having an endless photoreceptor belt supported by a plurality of rolls and arranged to move in a predetermined path through a plurality of processing stations disposed therealong the belt being of the type which is supported by a plurality of rolls. A roll for steering the belt is adapted for rotational movement about a first axis and tilting movement about a second axis transverse to the first axis. The steering roll further is cylindrical along its length, however the ends of the cylindrical portion of the roll are radiused to reduce the stress induced on the belt edge when the roll is tilted to effect steering of the belt. Additionally, the radiused ends may be filled with a compliant material to provide needed edge support while still reducing the stress induced at the belt edge.