Abstract: The present invention is a method and apparatus for generating N-bit per pixel output signals in response to M-bit per pixel image input signals, where M is greater than N. The invention employs a halftone cell threshold memory that stores a single threshold for each cell element. During real-time processing of the video image signals, multiple thresholds are calculated based upon the stored thresholds, and the image signals are compared to the thresholds. The threshold calculation process is simplified by using equally spaced constants and any desired variation from the resulting equally spaced thresholds is accomplished through a remapping of the video image signals using a look-up table. The output of the plurality of comparisons carried out for each halftone cell element is then encoded to produce a digital gray-scale output signal.

Abstract: The present invention is a method for automating the design of pattern matching templates used to implement a print quality enhancement filter. More particularly, the method is directed to the use of a representative set of page description language decomposed training documents, and statistical data derived therefrom, in an automated process which generates templates for resolution enhancement and/or conversion of bitmap images.

Abstract: The present invention is a method and apparatus for improving the appearance of printed documents, and more specifically, to the use of a template matching process to enhance the fast-scan resolution of digital images while maintaining raster resolution for printing. The present invention uses multiple-bit per pixel, statistically generated templates, implemented using look-up tables, to improve document appearance by converting from a single-bit per pixel to N-bits per pixel, while preserving raster resolution of the printed output. The resulting N-bit per pixel image signals may be utilized to control a scanning beam where the beam varies in intensity and duration according to the pulses used to control it.

Abstract: A reprographic system having one or more peripheral devices or subsystems whose function is integrated therewith, including a communications link between the reprographic system and peripheral devices. Furthermore, the reprographic system would have the capability to determine the configuration of electromechanical components contained within the peripheral devices, as well as, the status or control states of the components.

Abstract: A method and apparatus for converting the resolution of an input image to a higher resolution that is a noninteger multiple of the input resolution. The method and apparatus employ either an interlocked or noninterlocked clustering arrangement of output pixels in order to assign to each output pixel a reference value determined from the signal levels of the input image. In addition, the method and apparatus include a template-based enhancement filter to further refine modify or alter the assigned signal level prior to its output as a higher resolution image.

Abstract: A method for determining the relative equivalency or match between two or more character strings represented in an array of image data, including the steps of determining page orientation, isolating character strings from adjacent character strings, and establishing a set of boundaries or reference lines about the character strings. Subsequently, the boundaries are used to represent the character string images as word shape contours or signals which are generated from the imaginal data within the boundaries. The word shape contours are then compared using one of the described comparison methods to determine the relative equivalency or similarity of the contours.

Abstract: The present invention is a method and apparatus for tuning the appearance and controlling dot growth of bitmap images rendered on a printing system. The invention operates to recognize those pixels with a bitmap image that are appropriate for alteration and, in response to downloadable output values, adjusts the identified pixels so as to ensure a desired output.

Abstract: The present invention is a method and apparatus for mapping digital image data using paired erosion-based filters. One filter of the pair creates a superset of the output image data and the other a subset of the output image data, and combinatorial logic is then applied to the superset and subset data to obtain the mapped image data. In one embodiment a plurality of erosion-based filters are used where one filter of the pair is extensive and the other filter is antiextensive, each pair generating a sample phase of a high resolution output image.

Abstract: The present invention is a method and apparatus for tuning the appearance of bitmap images rendered on a printing system.

Abstract: The present invention is a method and apparatus for detecting the presence of image regions requiring compact dot growth control and controlling the dot growth of such regions when rendered on a printing system. The invention operates to recognize those pixels within a bitmap image that are appropriate for alteration, using a template-based approach, and then alters the exposure pulse of identified pixels during imaging so as to assure a more stable output by a xerographic development system.

Abstract: Patterns of intelligence detected in a digital image representation are correlated with pattern classes according to a predetermined set of rules for improved pattern identification. Identified patterns are subsequently mapped to classes for continued use of classification.

Abstract: The present invention is a multiple spot laser assembly, comprising a plurality of laser diodes, and a plurality of mounts, which include a support surface, upon which the laser diode are permanently affixed. The mounts, including the base plate and/or heat sink, further include a mating feature along an edge thereof for aligning a first mount with an adjacent mount, the two mounts abutting along at least one common edge. The mating features assure the accurate alignment of the laser diodes on the adjacent mounts when the mounts are assembled into a multispot laser light source.

Abstract: The present invention is a method and apparatus for consistently rotating high addressability bitmap images to be rendered on a printing system. The invention first encodes the high addressability image to produce a regular bitmap array and then rotates the regular array. Next the invention applies a compact dot growth operation to assure that the exposure pulses for any gray pixels are consistently positioned, thereby assuring consistent output-independent of the rotation direction.

Abstract: A contacting electrostatic voltmeter suitable for sampling positive or negative potentials on an electrostatically charged surface. The electrostatic voltmeter includes a selectively controllable actuation mechanism that enables the use of a contacting electrostatic voltmeter to sample the surface of an electrostatically charged member, moving relative thereto, within a predetermined space. The invention finds particular use in a printing system, where it enables charge monitoring during printing yet avoids disturbance to charged latent image areas on the imaging member.

Abstract: A digital color printing system having an input device such as a joystick is disclosed that provides real-time print quality control during a print run. The joystick is located near an output tray to enable an operator to perceive adjustments to print quality in real-time. The joystick modifies nominal electrostatic control points stored in non-volatile memory (NVM) of the printing system. Long term process controls are unchanged by joystick input, while short-term xerographic process controls are overridden by joystick commands. In one embodiment, joystick controls are used to adjust electrostatic controls which include adjusting developer bias and transfer current. In another embodiment, joystick controls also adjust, image processing parameters such as TRC curves. The new image processing parameters require that a contone image originally processed must be reprocessed to form a new raster image.

Abstract: A method for forming a plurality of halftone density patterns in an image processing system. Each density pattern is formed using a halftone cell that is incrementally grown according to a pixel growth pattern that is defined by the position of each threshold value in the halftone cell. The plurality of halftone density patterns are formed in accordance with at least two tests, one for an upper gray density boundary U(d) and one for a lower gray density boundary L(d). The two gray density boundary tests enables different density patterns having the same number of pixels but different densities to be formed by altering the growth pattern of the halftone cell. The two boundaries U(d) and L(d) define a valid range for each gray density threshold in a halftone cell. The defined range insures that pixels are added or removed along the pixel growth pattern of the halftone cell, thereby altering the perceived density of halftone density patterns having an equal number of pixels.

Abstract: A method and apparatus is disclosed for mapping original colors of image elements forming a color image to colors that appear solid when reproduced on a color printer. The original color and the solid color of each image element may be defined by a subtractive mixture of cyan, magenta and yellow colorants. The method first determines whether the original color of each image element is a light color surrounded by a dark background color, or a dark color surrounded by a light background color. Subsequently, the cyan and magenta colorants of each original color determined to be a light color surrounded by a dark background color are minimized; and one of the cyan or magenta colorants for each color determined to be dark and surrounded by a light background color is maximized. Consequently, image elements having colors defined by the mapping appear solid when reproduced by the color printer.

Abstract: Input device signals R.sub.s, G.sub.s, B.sub.s generated by an image input terminal are converted to colorimetric values R.sub.c, G.sub.c, B.sub.c. The colorimetric values processed by an image processing unit to generate address entries to a lookup table which stores a set of transform coefficients with which the R.sub.c, G.sub.c, B.sub.c values may be processed to convert them to C.sub.x, M.sub.x, Y.sub.x, K.sub.x colorant signals or any multi-dimensional output color space, which include but are not limited to CMYK or spectral data. Values which are not directly mapped from the table are determined using tetrahedral interpolation over a hexagonal lattice. The hexagonal lattice is formed by offsetting by a half unit every other row of one of its dimensions relative to another dimension. The offset provides closer packing of sample points that define more regular tetrahedrons to reduce relative interpolation errors.

Abstract: The present invention is a an apparatus for enhancing the output along edges of charged area developed regions in a tri-level imaging system employing a pulse width and position modulated signal ROS for exposure. The invention enables the identification and selective alteration of video data used to drive the ROS so as to extend the developed regions by a selected amount and eliminate digitization artifacts present in the image to be printed. The extension of the charged area developed regions is accomplished by reducing or trimming the width of the exposure pulses in adjacent areas to enable development within a portion of those regions.