Browse Prior Art Database

OPTICAL HALFTONING OF SCANNED IMAGES

IP.com Disclosure Number: IPCOM000025193D
Original Publication Date: 1983-Dec-31
Included in the Prior Art Database: 2004-Apr-04
Document File: 2 page(s) / 89K

Publishing Venue

Xerox Disclosure Journal

Abstract

Scanned input images may be optically halftoned prior to photodetection and the required modulation achieved by one of the following techniques: by control of the power source for an illuminator; by control of the light between the illumination source and an associated sensor; or by the addition of a secondary light source into the photodetector.

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(EROX DISCLOSURE JOURNAL

OPTICAL HALFTONING OF SCANNED IMAGES U.S. C1. 430/54 Louis D. Mailloux

Proposed Classification

Int. C1. G03g 13/00

Scanned input images may be optically halftoned prior to photodetection and the required modulation achieved by one of the following techniques: by control of the power source for an illuminator; by control of the light between the illumination source and an associated sensor; or by the addition of a secondary light source into the photodetector.

All of the techniques previously applicable to copier screening are analogously applicable to halftoning of scanned images such as, for example, multiplicative, additive projected, etc. If the scanning system is a polygon deflected laser beam, an acoustic modular could be used to periodically vary its intensity as a function of the horizontal and vertical position on the document. If the scanning system is a photodiode or charge coupled diode array, a beam splitter could add a second screened light image to the document images.

As shown in the accompanying figure, a halftoning system comprises a scanning system having a television camera 12 and an illumination source which may be, for example, a slide projector 14 containing a halftone screen 16. The projector 14 places a halftoned input image on surface 15 and the camera 12 scans the input image and converts the input image to video signals for transmittal to either a video tape recorder 18 or television (CRT) display 20. The display 20 may be placed on a color copier for the production of hard colored copies. The video tape recorder, of course,...