Facsimile and static presentation processing – Facsimile – Specific signal processing circuitry
Patent
1990-05-08
1992-11-24
Coles, Sr., Edward L.
Facsimile and static presentation processing
Facsimile
Specific signal processing circuitry
358457, 358460, 358465, H04N 140
Patent
active
051668092
ABSTRACT:
Disclosed are apparatus and methods for producing halftone screens (color separations) from continuous tone intensity signals that are supplied by an optical scanner (12) and are stored in memory (18-2, 18-3, 18-4 and 18-5) such that the memory addresses correspond to the Cartesian coordinates of the picture elements produced by the optical scanner. A digital signal processor (10) processes the stored continuous tone intensity values on a row-by-row basis with the memory elements in each row being sequentially accessed column-by-column. The memory addresses of the accessed continuous tone intensity signals are processed using an incremental addressing method that transforms the memory address into dither element column and row indices of a dither matrix (FIG. 4) that is used to produce the halftone dots of each halftone screen. The screen angle and the screen ruling of the halftone screens are selectively controlled and established by the incremental addressing method in view of the dither matrix and digital data output device being employed by the system. This allows the system operator to produce sets of halftone screens (e.g., the yellow, cyan and magenta color separations used in conventional four-color halftone printing) in which each each color separation exhibits the conventional screen angle and the screen ruling is established at a value that is appropriate for the color printing process to be employed. 1
REFERENCES:
patent: 3911480 (1975-10-01), Brucker
patent: 4547814 (1985-10-01), Hirosawa
patent: 4805033 (1989-02-01), Nishikawa
patent: 4924301 (1990-05-01), Surbrook
Coles Sr. Edward L.
Grant II Jerome
SeeColor Corporation
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