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IMAGE ENHANCEMENT BY MULTIPLE, ANGLED SEQUENTIAL EXPOSURES

IP.com Disclosure Number: IPCOM000024605D
Original Publication Date: 1981-Apr-30
Included in the Prior Art Database: 2004-Apr-02
Document File: 2 page(s) / 47K

Publishing Venue

Xerox Disclosure Journal

Abstract

In order to extend the brightness range of a high contrast process such as xerography, it is known to use halftone imaging techniques in which a continuous tone original is imaged twice, first to the original directly, then through a halftone line screen. Such techniques are known as sequential (SQ) halftoning exposures. It is also known that this method is limited in its effort since both high and low densities of the original cannot be reproduced with good fidelity.

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Proposed Classification
U.S. c1. 355/35c Int. C1. G03b 27/72

In order to extend the brightness range of a high contrast process such as xerography, it is known to use halftone imaging techniques in which a continuous tone original is imaged twice, first to the original directly, then through a halftone line screen. Such techniques are known as sequential (SQ) halftoning exposures. It is also known that this method is limited in its effort since both high and low densities of the original cannot be reproduced with good fidelity.

This limitation may be overcome by a method described wherein multiple, angled halftoning exposures are used. Each such exposure is a portion of the total halftoning exposure time, and each is made with the line screen pattern oriented at a different angle. The screen angle positions are chosen such that the amplitude of the resulting moire pattern is minimized.

IMAGE ENHANCEMENT BY MULTIPLE, ANGLED SEQUENTIAL EXPOSURES Kenneth C. Johnson

Volume 6 Number 2 March/April 1981 83

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XEROX 84 DISCLOSURE JOURNAL

Volume 6 Number 2 March/April 1981

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