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AssigneeXerox Corporation
InventorZhigang Fan
Estimating the term…
An image processing system converts screen structured halftone images to continuous tone images. Value data is sequentially generated for successive pixels of a halftone image. An averaging filter is provided for sequentially filtering each pixel in the halftone image in the horizontal image direction in accordance with a first predetermined filter to generate an intermediately filtered image. A pattern matching filter then sequentially filters each pixel in the intermediately filtered image in the vertical direction to generate a hybrid filtered image. The hybrid filter arrangement is then iteratively operated for three additional sets of orthogonal directions, i.e. the vertical and horizontal directions, a first diagonal direction and a second diagonal direction, and the second and first diagonal directions. The best hybrid image is generated as an output continuous tone image for storage and/or processing to a halftone copy or print.
An image processing system for converting screen structed halftone images to continuous tone images, said system comprising:
An image processing system for converting screen structured halftone images to continuous tone images, said system comprising:
Dependencies are inferred from the claim text.
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Picture signal circuits: descreening, i.e. converting a halftone signal into a corresponding continuous-tone signal; Rescreening, i.e. combined…
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Term ended 31 Dec 2011 (estimated)
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Reference is made to the following concurrently filed patent applications that are assigned to the present assignee and are hereby incorporated by reference: None.
The present invention relates to image processing systems and methods having a capability for processing halftone images to retrieve continuous tone images and more particularly to systems and methods for converting screen-structured scanned or orthographic halftone images to continuous tone images.
Continuous tone images are converted to halftone or binary images to enable the production of printed copies. In binary form, the image has pixels which are either black or white and which are printed by applying ink or not applying ink.
The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one embodiment of the invention and together with the description provide an explanation of the objects, advantages and principles of the invention. In the drawings:
FIG. 1 shows a reprographic system in which the present invention is applied;
FIGS. 2 and 3B, 3B show a flow chart representing a programmed procedure for converting a halftone image to a continuous tone image with the use of hybrid filtering in accordance with the present invention;
An image processing system 10 shown in FIG. 1 includes a conventional printer 12 that is operated in accordance with the invention by printer controls 14 under the control of a system computer 16. Input halftone images are obtained from a scanner 18 or from a first memory 20. Another memory 22 is used to store converted images for output.
In accordance with the invention, input black and white screen-structured images are first converted or "unscreened" to continuous tone images, and thereafter reconverted to halftone images for print processing. If desired, unprocessed halftone images can be stored in another memory (not shown) for subsequent conversion and processing in accordance with the present invention.
The scanned or stored input images are dithered images with a screen structure.