Xerox Corporation

Tse-Kee Chan

Fritz F Ebner

David Birnbaum

Michael Kerrigan Hawes

Stephen F Linder

Reiner Eschbach

Shen-Ge Wang

Scott A Bennett

Bradley W Smith

Marty S Maltz

A method and programmable gray scale halftoner with object oriented resolution capability apparatus are provided for selecting a resolution and gray level range to deliver halftone value data to an associated laser output device. The apparatus includes an input buffer adapted to receive a first group of n pixel data values, each having a resolution object tag associated therewith. A mapping circuit maps the first group of pixel data values to a first one of a plurality of resolution object tags. A first configurable gray scale halftone generator is adapted to generate n halftone values in a range of from 0-8 Bit Gray level modes, each of the n halftone values being associated with a single pixel data value among the first group of pixel data values. Second and third configurable gray scale halftone generators are each respectively adapted to generate n/2 and a single halftone value in a range of from 0-8 Bit Gray level modes. The single halftone value is an average pixel data value among the first group of pixel data values and the n/2 halftone values are multiple average values. A select circuit selects one of the halftone values from the set of gray scale halftone generators based on the first one of the plurality of resolution settings. An output signal line delivers the selected halftone value for use by an associated laser output device.

Programmable gray scale halftoner with object oriented resolution capability

Palletized image enhancement systems and methods enhance palletized images by &sgr;-filtering the palletized image. Palletized images, such as GIF images, are analyzed to obtain a number of &sgr; filter parameters based on the global image features of the palletized image. Local portions of the image data are analyzed to determine which of the &sgr; filter parameters should be used for each particular portion. The &sgr; filter parameters are determined based on histograms of the color palette of the palletized image data. As a result, a good balance between color re-creation and image sharpness in the enhanced palletized image is obtained.

Systems and methods for adaptively filtering palettized images

Image values are adjusted based on image object or component type and in a perceptually linear manner based on user set control values. Image values are also scaled based on dynamic ranges of an input and output device, such as a monitor and a printer. A lookup table is generated for converting image values from an adjustment color space to a printer color space by measuring a test print, inverting the measured data to an adjustment color space and generating a final lookup table based on the adjustment color space data and the inversion color space data. Image values are adjusted in a perceptually linear manner by converting the image values to a perceptually uniform color space and adjusting the values in the adjustment color space before converting the values to a printer device space.

Method and apparatus for object-oriented adjustment of color attributes in a perceptually uniform manner

A method and apparatus of rendering object oriented image data into a frame buffer of an imaging device using a set of rendering state information is provided. Object oriented image data is read into the imaging device together with an imaging operator associated with the object oriented image data. The object type of the imaging operator is determined. Based on the object type of the imaging operator, a set of rendering state information is selected from a plurality of sets of rendering state information stored beforehand in the imaging device. Using the rendering state information, the imaging device renders the object oriented image data into a frame buffer of the imaging device for ready display. Each different object type encountered by the imaging device, a renderstate pointer is loaded with index information so that an appropriate one of the plurality of sets of rendering state information can be quickly and easily accessed for integration into the current graphic state information set for rendering differing object types on the fly.

Method and apparatus for rendering object oriented image data using multiple rendering states selected based on imaging operator type

A system for trapping of a dark image object on a lighter colored background is disclosed. In a system using a page description language including overprint operators, black image areas (such as text, lines, graphic objects and the like) can be set to overprint colored background areas in a manner that eliminates rendered image defects including page-colored 'halo' effect that can occur when the cutout background area underlying the black object is misregistered with the black object that was intended to cover the cutout area. In other systems, the present invention may be employed as a disabling of the undercolor removal system of a colored area that would otherwise be present under the black object. Systems using black plus at least one other toners or ink color (such as cyan, magenta and/or yellow or many other colors) can usefully employ the system of the present invention. The trapping system of the present invention may also be employed on an object-oriented basis, such that different image object types are trapped according to the system of the present invention and at least one other trapping system.

Digital image trapping system

A hybrid system for digitally screening black and white and/or color images using a number of imaging techniques is disclosed. Cyan, yellow, magenta and black color separation may be processed according to the same or different methods according to gray levels or other factors, in order to optimize output print quality. A hybrid ordered matrix dot rendering system may be employed in part as an optimized screen technique in a variety of circumstances

Hybrid imaging system

A method of constructing a screen for halftoning a digitized image is described, in which a composite screen is established. A composite LUT having m times n rank ordered threshold elements is constructed for use in halftoning digitized images. A variety of optimization techniques can be employed to improve the visual appeal of the images rendered using the composite LUT for rendering a variety of image types in single or multicolored imaging applications.

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Penfield, NY, United States of America

Tse-Kee Chan